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  • 1.
    André, Mats
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Li, Wenya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Toledo-Redondo, S.
    European Space Agcy ESAC, Madrid, Spain..
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Norgren, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Burch, J.
    Southwest Res Inst, San Antonio, TX USA..
    Lindqvist, P. -A
    KTH, Stockholm, Sweden.
    Marklund, G.
    KTH, Stockholm, Sweden..
    Ergun, R.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Torbert, R.
    Southwest Res Inst, San Antonio, TX USA.;Univ New Hampshire, Durham, NH 03824 USA..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Giles, B.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Moore, T. E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Chandler, M. O.
    NASA, Marshall Space Flight Ctr, Huntsville, AL USA..
    Pollock, C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Young, D. T.
    Southwest Res Inst, San Antonio, TX USA..
    Avanov, L. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Lavraud, B.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France..
    Saito, Y.
    Inst Space & Astronaut Sci, JAXA, Chofu, Tokyo, Japan..
    Magnetic reconnection and modification of the Hall physics due to cold ions at the magnetopause2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 13, p. 6705-6712Article in journal (Refereed)
    Abstract [en]

    Observations by the four Magnetospheric Multiscale spacecraft are used to investigate the Hall physics of a magnetopause magnetic reconnection separatrix layer. Inside this layer of currents and strong normal electric fields, cold (eV) ions of ionospheric origin can remain frozen-in together with the electrons. The cold ions reduce the Hall current. Using a generalized Ohm's law, the electric field is balanced by the sum of the terms corresponding to the Hall current, the vxB drifting cold ions, and the divergence of the electron pressure tensor. A mixture of hot and cold ions is common at the subsolar magnetopause. A mixture of length scales caused by a mixture of ion temperatures has significant effects on the Hall physics of magnetic reconnection.

  • 2.
    André, Mats
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Odelstad, Elias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Eriksson, Anders I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Karlsson, T.
    KTH Royal Inst Technol, Sch Elect Engn, Dept Space & Plasma Phys, Stockholm, Sweden.
    Wieser, G. Stenberg
    Swedish Inst Space Phys, Kiruna, Sweden.
    Vigren, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Norgren, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Johansson, Fredrik L.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Henri, P.
    Lab Phys & Chim Environm & Espace, Orleans, France.
    Rubin, M.
    Univ Bern, Phys Inst, Bern, Switzerland.
    Richter, I.
    TU Braunschweig, Inst Geophys & Extraterr Phys, Braunschweig, Germany.
    Lower hybrid waves at comet 67P/Churyumov-Gerasimenko2017In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 469, p. S29-S38Article in journal (Refereed)
    Abstract [en]

    We investigate the generation of waves in the lower hybrid frequency range by density gradients in the near plasma environment of comet 67P/Churyumov-Gerasimenko. When the plasma is dominated by water ions from the comet, a situation with magnetized electrons and unmagnetized ions is favourable for the generation of lower hybrid waves. These waves can transfer energy between ions and electrons and reshape the plasma environment of the comet. We consider cometocentric distances out to a few hundred km. We find that when the electron motion is not significantly interrupted by collisions with neutrals, large average gradients within tens of km of the comet, as well as often observed local large density gradients at larger distances, are often likely to be favourable for the generation of lower hybrid waves. Overall, we find that waves in the lower hybrid frequency range are likely to be common in the near plasma environment.

  • 3.
    Breuillard, H.
    et al.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Le Contel, O.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Chust, T.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Berthomier, M.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Retino, A.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Turner, D. L.
    Aerosp Corp, Space Sci Dept, El Segundo, CA 90245 USA..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Baumjohann, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Cozzani, G.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Catapano, F.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Alexandrova, A.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Mirioni, L.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Argall, M. R.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Fischer, D.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Wilder, F. D.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Varsani, A.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Lindqvist, P. -A
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Marklund, G.
    Royal Inst Technol, Stockholm, Sweden..
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Goodrich, K. A.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Ahmadi, N.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Torbert, R. B.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Needell, G.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Chutter, M.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Rau, D.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Dors, I.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Strangeway, R. J.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Bromund, K. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Wei, H.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Anderson, B. J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Le, G.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Moore, T. E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Avanov, L. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Saito, Y.
    Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan..
    Lavraud, B.
    Univ Paul Sabatier, CNRS UMR5277, Inst Rech Astrophys & Planetol, Toulouse, France..
    Fuselier, S. A.
    Southwest Res Inst, San Antonio, TX USA..
    Mauk, B. H.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Cohen, I. J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Fennell, J. F.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    The Properties of Lion Roars and Electron Dynamics in Mirror Mode Waves Observed by the Magnetospheric MultiScale Mission2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 1, p. 93-103Article in journal (Refereed)
    Abstract [en]

    Mirror mode waves are ubiquitous in the Earth's magnetosheath, in particular behind the quasi‐perpendicular shock. Embedded in these nonlinear structures, intense lion roars are often observed. Lion roars are characterized by whistler wave packets at a frequency ∼100 Hz, which are thought to be generated in the magnetic field minima. In this study, we make use of the high time resolution instruments on board the Magnetospheric MultiScale mission to investigate these waves and the associated electron dynamics in the quasi‐perpendicular magnetosheath on 22 January 2016. We show that despite a core electron parallel anisotropy, lion roars can be generated locally in the range 0.05–0.2fce by the perpendicular anisotropy of electrons in a particular energy range. We also show that intense lion roars can be observed up to higher frequencies due to the sharp nonlinear peaks of the signal, which appear as sharp spikes in the dynamic spectra. As a result, a high sampling rate is needed to estimate correctly their amplitude, and the latter might have been underestimated in previous studies using lower time resolution instruments. We also present for the first‐time 3‐D high time resolution electron velocity distribution functions in mirror modes. We demonstrate that the dynamics of electrons trapped in the mirror mode structures are consistent with the Kivelson and Southwood (1996) model. However, these electrons can also interact with the embedded lion roars: first signatures of electron quasi‐linear pitch angle diffusion and possible signatures of nonlinear interaction with high‐amplitude wave packets are presented. These processes can lead to electron untrapping from mirror modes.

  • 4.
    Breuillard, H.
    et al.
    CNRS, LPP, UMR, Paris, France..
    Le Contel, O.
    CNRS, LPP, UMR, Paris, France..
    Retino, A.
    CNRS, LPP, UMR, Paris, France..
    Chasapis, A.
    Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA..
    Chust, T.
    CNRS, LPP, UMR, Paris, France..
    Mirioni, L.
    CNRS, LPP, UMR, Paris, France..
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wilder, F. D.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Cohen, I.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lindqvist, P. -A
    Royal Inst Technol, Alfven Lab, Stockholm, Sweden.
    Marklund, G. T.
    Royal Inst Technol, Alfven Lab, Stockholm, Sweden..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Torbert, R. B.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Ergun, R. E.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Goodrich, K. A.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Macri, J.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Needell, J.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Chutter, M.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Rau, D.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Dors, I.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst IWF, Graz, Austria..
    Strangeway, R. J.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Bromund, K. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst IWF, Graz, Austria..
    Fischer, D.
    Austrian Acad Sci, Space Res Inst IWF, Graz, Austria..
    Leinweber, H. K.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Anderson, B. J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Le, G.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Slavin, J. A.
    Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI 48109 USA..
    Kepko, E. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Baumjohann, W.
    Austrian Acad Sci, Space Res Inst IWF, Graz, Austria..
    Mauk, B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fuselier, S. A.
    Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX USA..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst IWF, Graz, Austria..
    Multispacecraft analysis of dipolarization fronts and associated whistler wave emissions using MMS data2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 14, p. 7279-7286Article in journal (Refereed)
    Abstract [en]

    Dipolarization fronts (DFs), embedded in bursty bulk flows, play a crucial role in Earth's plasma sheet dynamics because the energy input from the solar wind is partly dissipated in their vicinity. This dissipation is in the form of strong low-frequency waves that can heat and accelerate energetic electrons up to the high-latitude plasma sheet. However, the dynamics of DF propagation and associated low-frequency waves in the magnetotail are still under debate due to instrumental limitations and spacecraft separation distances. In May 2015 the Magnetospheric Multiscale (MMS) mission was in a string-of-pearls configuration with an average intersatellite distance of 160km, which allows us to study in detail the microphysics of DFs. Thus, in this letter we employ MMS data to investigate the properties of dipolarization fronts propagating earthward and associated whistler mode wave emissions. We show that the spatial dynamics of DFs are below the ion gyroradius scale in this region (approximate to 500km), which can modify the dynamics of ions in the vicinity of the DF (e.g., making their motion nonadiabatic). We also show that whistler wave dynamics have a temporal scale of the order of the ion gyroperiod (a few seconds), indicating that the perpendicular temperature anisotropy can vary on such time scales.

  • 5.
    Breuillard, H.
    et al.
    Univ Paris Sud, Sorbonne Univ, Ecole Polytech, Lab Phys Plasmas,UMR7648,CNRS, Paris, France.
    Matteini, L.
    UPMC Univ Paris 06, Univ Paris Diderot, PSL Res Univ, LESIA Observ Paris,CNRS, Meudon, France.
    Argall, M. R.
    Univ New Hampshire, Durham, NH 03824 USA.
    Sahraoui, F.
    Univ Paris Sud, Sorbonne Univ, Ecole Polytech, Lab Phys Plasmas,UMR7648,CNRS, Paris, France.
    Andriopoulou, M.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.
    Le Contel, O.
    Univ Paris Sud, Sorbonne Univ, Ecole Polytech, Lab Phys Plasmas,UMR7648,CNRS, Paris, France.
    Retino, A.
    Univ Paris Sud, Sorbonne Univ, Ecole Polytech, Lab Phys Plasmas,UMR7648,CNRS, Paris, France.
    Mirioni, L.
    Univ Paris Sud, Sorbonne Univ, Ecole Polytech, Lab Phys Plasmas,UMR7648,CNRS, Paris, France.
    Huang, S. Y.
    Wuhan Univ, Sch Elect & Informat, Beijing, Peoples R China.
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Wilder, F. D.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Goodrich, K. A.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Ahmadi, N.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Yordanova, Emiliya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Turner, D. L.
    Aerosp Corp, Space Sci Dept, El Segundo, CA 90245 USA.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lindqvist, P. -A
    Chasapis, A.
    Univ Delaware, Newark, DE USA.
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA.
    Torbert, R. B.
    Univ New Hampshire, Durham, NH 03824 USA.
    Russell, C. T.
    Univ Calif Los Angeles, Los Angeles, CA USA.
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.
    Strangeway, R. J.
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.
    Moore, T. E.
    Giles, B. L.
    Paterson, W. R.
    Pollock, C. J.
    Lavraud, B.
    Univ Paul Sabatier, CNRS UMR5277, IRAP, Toulouse, France.
    Fuselier, S. A.
    Southwest Res Inst, San Antonio, TX USA.
    Cohen, I. J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA.
    New Insights into the Nature of Turbulence in the Earth's Magnetosheath Using Magnetospheric MultiScale Mission Data2018In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 859, no 2, article id 127Article in journal (Refereed)
    Abstract [en]

    The Earth's magnetosheath, which is characterized by highly turbulent fluctuations, is usually divided into two regions of different properties as a function of the angle between the interplanetary magnetic field and the shock normal. In this study, we make use of high-time resolution instruments on board the Magnetospheric MultiScale spacecraft to determine and compare the properties of subsolar magnetosheath turbulence in both regions, i. e., downstream of the quasi-parallel and quasi-perpendicular bow shocks. In particular, we take advantage of the unprecedented temporal resolution of the Fast Plasma Investigation instrument to show the density fluctuations down to sub-ion scales for the first time. We show that the nature of turbulence is highly compressible down to electron scales, particularly in the quasi-parallel magnetosheath. In this region, the magnetic turbulence also shows an inertial (Kolmogorov-like) range, indicating that the fluctuations are not formed locally, in contrast with the quasi-perpendicular magnetosheath. We also show that the electromagnetic turbulence is dominated by electric fluctuations at sub-ion scales (f > 1Hz) and that magnetic and electric spectra steepen at the largest-electron scale. The latter indicates a change in the nature of turbulence at electron scales. Finally, we show that the electric fluctuations around the electron gyrofrequency are mostly parallel in the quasi-perpendicular magnetosheath, where intense whistlers are observed. This result suggests that energy dissipation, plasma heating, and acceleration might be driven by intense electrostatic parallel structures/waves, which can be linked to whistler waves.

  • 6.
    Burch, J. L.
    et al.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Dokgo, K.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Hwang, K. J.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Torbert, R. B.
    Southwest Res Inst, San Antonio, TX 78238 USA;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Webster, J. M.
    Rice Univ, Dept Phys & Astron, Houston, TX USA.
    Ergun, R. E.
    Univ Colorado, LASP, Boulder, CO 80309 USA.
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Allen, R. C.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA.
    Chen, L-J
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Wang, S.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA.
    Genestreti, K. J.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.
    Russell, C. T.
    Univ Calif Los Angeles, Earth & Planetary Sci, Los Angeles, CA USA.
    Strangeway, R. J.
    Univ Calif Los Angeles, Earth & Planetary Sci, Los Angeles, CA USA.
    Le Contel, O.
    Univ Paris Sud, Observ Paris, Sorbonne Univ, Lab Phys Plasmas,CNRS,Ecole Polytech, Paris, France.
    High-Frequency Wave Generation in Magnetotail Reconnection: Linear Dispersion Analysis2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 8, p. 4089-4097Article in journal (Refereed)
    Abstract [en]

    Plasma and wave measurements from the NASA Magnetospheric Multiscale mission are presented for magnetotail reconnection events on 3 July and 11 July 2017. Linear dispersion analyses were performed using distribution functions comprising up to six drifting bi-Maxwellian distributions. In both events electron crescent-shaped distributions are shown to be responsible for upper hybrid waves near the X-line. In an adjacent location within the 3 July event a monodirectional field-aligned electron beam drove parallel-propagating beam-mode waves. In the 11 July event an electron distribution consisting of a drifting core and two crescents was shown to generate upper-hybrid and beam-mode waves at three different frequencies, explaining the observed broadband waves. Multiple harmonics of the upper hybrid waves were observed but cannot be explained by the linear dispersion analysis since they result from nonlinear beam interactions. Plain Language Summary Magnetic reconnection is a process that occurs throughout the universe in ionized gases (plasmas) containing embedded magnetic fields. This process converts magnetic energy to electron and ion energy, causing phenomena such as solar flares and auroras. The NASA Magnetospheric Multiscale mission has shown that in magnetic reconnection regions there are intense electric field oscillations or waves and that electrons form crescent and beam-like populations propagating both along and perpendicular to the magnetic field. This study shows that the observed electron populations are responsible for high-frequency waves including their propagation directions and frequency ranges.

  • 7.
    Burch, J. L.
    et al.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Ergun, R. E.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Cassak, P. A.
    Univ Virginia, Dept Phys & Astron, Morgantown, WV USA..
    Webster, J. M.
    Rice Univ, Dept Phys & Astron, Houston, TX USA..
    Torbert, R. B.
    Southwest Res Inst, San Antonio, USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Rager, A. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA..
    Hwang, K. -J
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Phan, T. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Genestreti, K. J.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Allen, R. C.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Chen, L. -J
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA.
    Wang, S.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Gershman, D.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Le Contel, O.
    Univ Paris Sud, Observ Paris, Lab Phys Plasmas, CNRS,Ecole Polytech,UPMC Univ Paris 06, Paris, France..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Planetary Sci, Los Angeles, CA USA..
    Strangeway, R. J.
    Univ Calif Los Angeles, Dept Earth & Planetary Sci, Los Angeles, CA USA..
    Wilder, F. D.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Hesse, M.
    Univ Bergen, Dept Phys & Technol, Bergen, Norway..
    Drake, J. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Swisdak, M.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Price, L. M.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Shay, M. A.
    Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA..
    Lindqvist, P. -A
    Royal Inst Technol, Dept Space & Plasma Phys, Stockholm, Sweden.
    Pollock, C. J.
    Denali Sci, Healy, AK USA..
    Denton, R. E.
    Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA..
    Newman, D. L.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Localized Oscillatory Energy Conversion in Magnetopause Reconnection2018In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 3, p. 1237-1245Article in journal (Refereed)
    Abstract [en]

    Data from the NASA Magnetospheric Multiscale mission are used to investigate asymmetric magnetic reconnection at the dayside boundary between the Earth's magnetosphere and the solar wind. High-resolution measurements of plasmas and fields are used to identify highly localized (similar to 15 electron Debye lengths) standing wave structures with large electric field amplitudes (up to 100 mV/m). These wave structures are associated with spatially oscillatory energy conversion, which appears as alternatingly positive and negative values of J . E. For small guide magnetic fields the wave structures occur in the electron stagnation region at the magnetosphere edge of the electron diffusion region. For larger guide fields the structures also occur near the reconnection X-line. This difference is explained in terms of channels for the out-of-plane current (agyrotropic electrons at the stagnation point and guide field-aligned electrons at the X-line).

  • 8.
    Burch, J. L.
    et al.
    Southwest Res Inst, San Antonio, TX, USA.
    Webster, J. M.
    Rice Univ, Dept Phys & Astron, Houston, TX USA.
    Genestreti, K. J.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.
    Torbert, R. B.
    Southwest Res Inst, San Antonio, TX, USA; Univ New Hampshire, Dept Phys, Durham, NH, USA.
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Fuselier, S. A.
    Southwest Res Inst, San Antonio, TX, USA.
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Rager, A. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA; Catholic Univ Amer, Dept Phys, Washington DC, USA..
    Phan, T. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA, USA.
    Allen, R. C.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA.
    Chen, L. -J
    Univ Maryland, Dept Astron, College Pk, MD, USA.
    Wang, S.
    Univ Maryland, Dept Astron, College Pk, MD, USA.
    Le Contel, O.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, CNRS, Ecole Polytech,Observ Paris, Paris, France.
    Russell, C. T.
    Univ Calif Los Angeles, Earth & Planetary Sci, Los Angeles, CA, USA.
    Strangeway, R. J.
    Univ Calif Los Angeles, Earth & Planetary Sci, Los Angeles, CA, USA.
    Ergun, R. E.
    Univ Colorado, LASP, Boulder, CO, USA.
    Jaynes, A. N.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA, USA.
    Lindqvist, P. -A
    Royal Inst Technol, Stockholm, Sweden.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wilder, F. D.
    Univ Colorado, LASP, Boulder, CO, USA.
    Hwang, K. -J
    Southwest Res Inst, San Antonio, TX, USA.
    Goldstein, J.
    Southwest Res Inst, San Antonio, TX, USA.
    Wave Phenomena and Beam-Plasma Interactions at the Magnetopause Reconnection Region2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 2, p. 1118-1133Article in journal (Refereed)
    Abstract [en]

    This paper reports on Magnetospheric Multiscale observations of whistler mode chorus and higher-frequency electrostatic waves near and within a reconnection diffusion region on 23 November 2016. The diffusion region is bounded by crescent-shaped electron distributions and associated dissipation just upstream of the X-line and by magnetic field-aligned currents and electric fields leading to dissipation near the electron stagnation point. Measurements were made southward of the X-line as determined by southward directed ion and electron jets. We show that electrostatic wave generation is due to magnetosheath electron beams formed by the electron jets as they interact with a cold background plasma and more energetic population of magnetospheric electrons. On the magnetosphere side of the X-line the electron beams are accompanied by a strong perpendicular electron temperature anisotropy, which is shown to be the source of an observed rising-tone whistler mode chorus event. We show that the apex of the chorus event and the onset of electrostatic waves coincide with the opening of magnetic field lines at the electron stagnation point.

  • 9.
    Cao, D.
    et al.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Fu, H. S.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Cao, J. B.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Wang, T. Y.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Chen, Z. Z.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Peng, F. Z.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Huang, S. Y.
    Wuhan Univ, Sch Elect & Informat, Wuhan, Peoples R China.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Russell, C. T.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA.
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Lindqvist, P. -A
    Torbert, R. B.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.
    Ergun, R. E.
    Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA.
    Le Contel, O.
    UPMC, Ecole Polytech, CNRS, Lab Phys Plasmas, Palaiseau, France.
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA.
    MMS observations of whistler waves in electron diffusion region2017In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 44, no 9, p. 3954-3962Article in journal (Refereed)
    Abstract [en]

    Whistler waves that can produce anomalous resistivity by affecting electrons' motion have been suggested as one of the mechanisms responsible for magnetic reconnection in the electron diffusion region (EDR). Such type of waves, however, has rarely been observed inside the EDR so far. In this study, we report such an observation by Magnetospheric Multiscale (MMS) mission. We find large-amplitude whistler waves propagating away from the X line with a very small wave-normal angle. These waves are probably generated by the perpendicular temperature anisotropy of the -300eV electrons inside the EDR, according to our analysis of dispersion relation and cyclotron resonance condition; they significantly affect the electron-scale dynamics of magnetic reconnection and thus support previous simulations.

  • 10.
    Dokgo, Kyunghwan
    et al.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Hwang, Kyoung-Joo
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Burch, James L.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Choi, Eunjin
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Yoon, Peter H.
    Univ Maryland, Inst Phys Sci & Technol, College Pk, MD 20742 USA;Kyung Hee Univ, Sch Space Res, Yongin, South Korea;Korea Astron & Space Sci Inst, Daejeon, South Korea.
    Sibeck, David G.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Swedish Inst Space Phys, Uppsala, Sweden.
    High-Frequency Wave Generation in Magnetotail Reconnection: Nonlinear Harmonics of Upper Hybrid Waves2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 14, p. 7873-7882Article in journal (Refereed)
    Abstract [en]

    MMS3 spacecraft passed the vicinity of the electron diffusion region of magnetotail reconnection on 3 July 2017, observing discrepancies between perpendicular electron bulk velocities and (E) over right arrow x (B) over right arrow drift, and agyrotropic electron crescent distributions. Analyzing linear wave dispersions, Burch et al. (2019, https://doi.org/10.1029/2019GL082471) showed the electron crescent generates high-frequency waves. We investigate harmonics of upper-hybrid (UH) waves using both observation and particle-in-cell (PIC) simulation, and the generation of electromagnetic radiation from PIC simulation. Harmonics of UH are linearly polarized and propagate along the perpendicular direction to the ambient magnetic field. Compared with two-dimensional PIC simulation and nonlinear kinetic theory, we show that the nonlinear beam-plasma interaction between the agyrotropic electrons and the core electrons generates harmonics of UH. Moreover, PIC simulation shows that agyrotropic electron beam can lead to electromagnetic (EM) radiation at the plasma frequency and harmonics.

  • 11.
    Ergun, R. E.
    et al.
    Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA.;Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80309 USA..
    Chen, L. -J
    Wilder, F. D.
    Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80309 USA..
    Ahmadi, N.
    Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80309 USA..
    Eriksson, S.
    Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80309 USA..
    Usanova, M. E.
    Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80309 USA..
    Goodrich, K. A.
    Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA.;Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80309 USA..
    Holmes, J. C.
    Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA.;Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80309 USA..
    Sturner, A. P.
    Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA.;Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80309 USA..
    Malaspina, D. M.
    Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80309 USA..
    Newman, D. L.
    Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80309 USA.;Univ Colorado, Dept Phys, Boulder, CO 80309 USA..
    Torbert, R. B.
    Univ New Hampshire, Durham, NH 03824 USA.;Southwest Res Inst, San Antonio, TX USA..
    Argall, M. R.
    Univ New Hampshire, Durham, NH 03824 USA..
    Lindqvist, P. -A
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Webster, J. M.
    Southwest Res Inst, San Antonio, TX USA..
    Drake, J. F.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Price, L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Cassak, P. A.
    West Virginia Univ, Morgantown, WV USA..
    Swisdak, M.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Shay, M. A.
    Univ Delaware, Newark, DE USA..
    Graham, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Strangeway, R. J.
    Univ Calif Los Angeles, Los Angeles, CA USA..
    Russell, C. T.
    Univ Calif Los Angeles, Los Angeles, CA USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Gershman, D.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, IREAP, College Pk, MD 20742 USA..
    Avanov, L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Hesse, M.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Lavraud, B.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;Ctr Natl Rech Sci, Toulouse, France..
    Le Contel, O.
    Lab Phys Plasmas, Palaiseau, France..
    Retino, A.
    Lab Phys Plasmas, Palaiseau, France..
    Phan, T. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Goldman, M. V.
    Univ Colorado, Dept Phys, Boulder, CO 80309 USA..
    Stawarz, J. E.
    Imperial Coll London, Blackett Lab, London, England..
    Schwartz, S. J.
    Imperial Coll London, Blackett Lab, London, England..
    Eastwood, J. P.
    Imperial Coll London, Blackett Lab, London, England..
    Hwang, K. -J
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Wang, S.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, IREAP, College Pk, MD 20742 USA..
    Drift waves, intense parallel electric fields, and turbulence associated with asymmetric magnetic reconnection at the magnetopause2017In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 44, no 7, p. 2978-2986Article in journal (Refereed)
    Abstract [en]

    Observations of magnetic reconnection at Earth's magnetopause often display asymmetric structures that are accompanied by strong magnetic field (B) fluctuations and large-amplitude parallel electric fields (E-||). The B turbulence is most intense at frequencies above the ion cyclotron frequency and below the lower hybrid frequency. The B fluctuations are consistent with a thin, oscillating current sheet that is corrugated along the electron flow direction (along the X line), which is a type of electromagnetic drift wave. Near the X line, electron flow is primarily due to a Hall electric field, which diverts ion flow in asymmetric reconnection and accompanies the instability. Importantly, the drift waves appear to drive strong parallel currents which, in turn, generate large-amplitude (similar to 100mV/m) E-|| in the form of nonlinear waves and structures. These observations suggest that turbulence may be common in asymmetric reconnection, penetrate into the electron diffusion region, and possibly influence the magnetic reconnection process.

  • 12.
    Eriksson, Elin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Alm, Love
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Electron acceleration in a magnetotail reconnection outflow region using Magnetospheric MultiScale dataManuscript (preprint) (Other academic)
  • 13.
    Eriksson, Elin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Divin, Andrey
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Physics Department, St. Petersburg State University, St. Petersburg, Russia.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Yordanova, Emiliya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Electron Energization at a Reconnecting Magnetosheath Current Sheet2018In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 16Article in journal (Refereed)
    Abstract [en]

    We present observations of electron energization within a sub-ion-scale magnetosheath current sheet (CS). A number of signatures indicate ongoing reconnection, including the thickness of the CS (∼0.7 ion inertial length), nonzero normal magnetic field, Hall magnetic fields with electrons carrying the Hall currents, and electron heating. We observe localized electron acceleration and heating parallel to the magnetic field at the edges of the CS. Electrostatic waves observed in these regions have low phase velocity and small wave potentials and thus cannot provide the observed acceleration and heating. Instead, we find that the electrons are accelerated by a parallel potential within the separatrix regions. Similar acceleration has been reported based on magnetopause and magnetotail observations.Thus, despite the different plasma conditions in magnetosheath, magnetopause, and magnetotail,the acceleration mechanism and corresponding heating of electrons is similar.

  • 14.
    Eriksson, Elin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel. B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Yordanova, Emiliya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Hietala, H.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA USA..
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Avanov, L. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Lavraud, B.
    CNRS, IRAP, Toulouse, France..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Saito, Y.
    JAXA, Chofu, Tokyo, Japan..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Russell, C.
    Torbert, R.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA..
    Ergun, R.
    Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA..
    Lindqvist, P-A
    Burch, J.
    Southwest Res Inst, San Antonio, TX USA..
    Strong current sheet at a magnetosheath jet: Kinetic structure and electron acceleration2016In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 121, no 10, p. 9608-9618Article in journal (Refereed)
    Abstract [en]

    Localized kinetic-scale regions of strong current are believed to play an important role in plasma thermalization and particle acceleration in turbulent plasmas. We present a detailed study of a strong localized current, 4900 nA m(-2), located at a fast plasma jet observed in the magnetosheath downstream of a quasi-parallel shock. The thickness of the current region is similar to 3 ion inertial lengths and forms at a boundary separating magnetosheath-like and solar wind-like plasmas. On ion scales the current region has the shape of a sheet with a significant average normal magnetic field component but shows strong variations on smaller scales. The dynamic pressure within the magnetosheath jet is over 3 times the solar wind dynamic pressure. We suggest that the current sheet is forming due to high velocity shears associated with the jet. Inside the current sheet we observe local electron acceleration, producing electron beams, along the magnetic field. However, there is no clear sign of ongoing reconnection. At higher energies, above the beam energy, we observe a loss cone consistent with part of the hot magnetosheath-like electrons escaping into the colder solar wind-like plasma. This suggests that the acceleration process within the current sheet is similar to the one that occurs at shocks, where electron beams and loss cones are also observed. Therefore, electron beams observed in the magnetosheath do not have to originate from the bow shock but can also be generated locally inside the magnetosheath.

  • 15.
    Fuselier, S. A.
    et al.
    Southwest Res Inst, San Antonio, TX 78238 USA;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX 78249 USA.
    Trattner, K. J.
    Univ Colorado, Atmospher & Space Phys Lab, Campus Box 392, Boulder, CO 80309 USA.
    Petrinec, S. M.
    Lockheed Martin Adv Technol Ctr, Palo Alto, CA USA.
    Denton, M. H.
    New Mexico Consortium, Los Alamos, NM USA.
    Toledo-Redondo, S.
    Univ Toulouse, Inst Rech Astrophys & Planetol, CNRS, UPS,CNES, Toulouse, France.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Aunai, N.
    Lab Phys Plasmas, Paris, France.
    Chappell, C. R.
    Vanderbilt Univ, Dept Phys & Astron, Nashville, TN 37235 USA.
    Glocer, A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Haaland, S. E.
    Max Planck Inst Solar Syst Res, Gottingen, Germany;Univ Bergen, Birkeland Ctr Space Sci, Bergen, Norway.
    Hesse, M.
    Univ Bergen, Birkeland Ctr Space Sci, Bergen, Norway.
    Kistler, L. M.
    Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA.
    Lavraud, B.
    Univ Toulouse, Inst Rech Astrophys & Planetol, CNRS, UPS,CNES, Toulouse, France.
    Li, W.
    Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China.
    Moore, T. E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Alm, Love
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Tenfjord, P.
    Univ Bergen, Birkeland Ctr Space Sci, Bergen, Norway.
    Dargent, J.
    Univ Pisa, Phys Dept E Fermi, Pisa, Italy.
    Vines, S. K.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA.
    Nykyri, K.
    Embry Riddle Aeronaut Univ, Ctr Space & Atmospher Res, Daytona Beach, FL USA.
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Strangeway, R. J.
    Univ Calif Los Angeles, Earth & Space Sci, Los Angeles, CA USA.
    Mass Loading the Earth's Dayside Magnetopause Boundary Layer and Its Effect on Magnetic Reconnection2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 12, p. 6204-6213Article in journal (Refereed)
    Abstract [en]

    When the interplanetary magnetic field is northward for a period of time, O+ from the high-latitude ionosphere escapes along reconnected magnetic field lines into the dayside magnetopause boundary layer. Dual-lobe reconnection closes these field lines, which traps O+ and mass loads the boundary layer. This O+ is an additional source of magnetospheric plasma that interacts with magnetosheath plasma through magnetic reconnection. This mass loading and interaction is illustrated through analysis of a magnetopause crossing by the Magnetospheric Multiscale spacecraft. While in the O+-rich boundary layer, the interplanetary magnetic field turns southward. As the Magnetospheric Multiscale spacecraft cross the high-shear magnetopause, reconnection signatures are observed. While the reconnection rate is likely reduced by the mass loading, reconnection is not suppressed at the magnetopause. The high-latitude dayside ionosphere is therefore a source of magnetospheric ions that contributes often to transient reduction in the reconnection rate at the dayside magnetopause.

  • 16.
    Fuselier, S. A.
    et al.
    Southwest Res Inst, San Antonio, TX 78238 USA.;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX 78249 USA..
    Vines, S. K.
    Southwest Res Inst, San Antonio, TX 78238 USA.;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX 78249 USA.;Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Petrinec, S. M.
    Lockheed Martin Adv Technol Ctr, Palo Alto, CA USA..
    Trattner, K. J.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Cassak, P. A.
    West Virginia Univ, Dept Phys & Astron, Morgantown, WV 26506 USA..
    Chen, L. -J
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Eriksson, S.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Giles, B. L.
    Goddard Space Flight Ctr, Greenbelt, MD USA..
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lavraud, B.
    Univ Toulouse, Inst Rech Astrophys & Plantol, Toulouse, France.;CNRS, Toulouse, France..
    Lewis, W. S.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Mukherjee, J.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Norgren, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Phan, T. -D
    Russell, C. T.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Strangeway, R. J.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Torbert, R. B.
    Southwest Res Inst, San Antonio, TX 78238 USA.;Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA..
    Webster, J. M.
    Rice Univ, Phys & Astron, Houston, TX USA..
    Large-scale characteristics of reconnection diffusion regions and associated magnetopause crossings observed by MMS2017In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 122, no 5, p. 5466-5486Article in journal (Refereed)
    Abstract [en]

    The Magnetospheric Multiscale (MMS) mission was designed to make observations in the very small electron diffusion region (EDR), where magnetic reconnection takes place. From a data set of over 4500 magnetopause crossings obtained in the first phase of the mission, MMS had encounters near or within 12 EDRs. These 12 events and associated magnetopause crossings are considered as a group to determine if they span the widest possible range of external and internal conditions (i.e., in the solar wind and magnetosphere). In addition, observations from MMS are used to determine if there are multiple X-lines present and also to provide information on X-line location relative to the spacecraft. These 12 events represent nearly the widest possible range of conditions at the dayside magnetopause. They occur over a wide range of local times and magnetic shear angles between the magnetosheath and magnetospheric magnetic fields. Most show evidence for multiple reconnection sites.

  • 17.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Cairns, Iver H.
    Constraints on the Formation and Structure of Langmuir Eigenmodes in the Solar Wind2013In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 111, no 12, p. 121101-Article in journal (Refereed)
    Abstract [en]

    Localized Langmuir waves are commonly observed in space plasmas and are a potential source of radio waves. Using electric field data from STEREO, it is shown that these localized Langmuir waves are eigenmodes of density wells estimated independently. An analytic model is developed for the eigenmode frequencies. The inferred depths and widths of the density wells typically only allow the zeroth-order Langmuir eigenmode to form, explaining the preponderance of single-peaked waveforms. More complicated waveforms are shown to be consistent with single eigenmode solutions of more complicated density profiles. The inferred depth of the density well increases with Langmuir wave intensity, consistent with the ponderomotive force but not wave packet collapse.

  • 18.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Cairns, Iver H.
    Dynamical evidence for nonlinear Langmuir wave processes in type III solar radio bursts2014In: J GEOPHYS RES-SPACE, ISSN 2169-9380, Vol. 119, no 4, p. 2430-2457Article in journal (Refereed)
    Abstract [en]

    The nonlinear processes and evolution of Langmuir waves in the source regions of type III solar radio bursts are explored in detail. Langmuir waves recorded by the Time Domain Sampler of the STEREO/WAVES instrument can be roughly classified into six groups based on the waveform, power spectra, and field strength perpendicular to the local magnetic field. It is argued that these groups correspond to either different stages of the evolution of Langmuir waves generated by electron beams or differ due to the direction of the magnetic field relative to the solar wind velocity. Approximately half of the observed Langmuir waves have strong perpendicular fields, meaning that understanding how these fields are produced is crucial for understanding type III sources. Most events recorded are either localized waveforms consistent with Langmuir eigenmodes or have two or more spectral peaks consistent with electrostatic (ES) decay of Langmuir/z mode waves. The remaining events appear to correspond to either earlier or later stages of Langmuir wave evolution or are decay events for which the Doppler shift is insufficient to distinguish the beam-driven and product Langmuir waves. This is supported by the fact that most events exceed the threshold for ES decay even though their spectra show no evidence for decay and some of the events are observed when the solar wind flow is approximately perpendicular to the magnetic field, minimizing Doppler shifting. Low-frequency fields produced by intense Langmuir waves are quantitatively consistent with density perturbations produced by the ponderomotive force, ion-acoustic waves produced by ES decay, or sheath rectification. Above the observed nonlinear threshold, quantitative analysis suggests that the observed low-frequency signals are consistent with perturbations produced by ponderomotive effects and ion-acoustic waves produced by ES decay, but effects of sheath rectification may also contribute.

  • 19.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Cairns, Iver H.
    Electrostatic decay of Langmuir/z-mode waves in type III solar radio bursts2013In: Journal of Geophysical Research-Space Physics, ISSN 2169-9380, Vol. 118, no 7, p. 3968-3984Article in journal (Refereed)
    Abstract [en]

    About 40% of the waveforms observed by STEREO during type III solar radio bursts exhibits Langmuir beating and have split spectral peaks, suggestive of decay into product Langmuir and ion-acoustic waves. For lower electron beam speeds v(b)/c less than or similar to 0.1, the spectra of Langmuir events with split spectral peaks are shown to be consistent with electrostatic (ES) decay into Langmuir-like waves with frequencies above the electron plasma frequency. For faster beam speeds vb/c0.1, the spectra are consistent with one or more successive generations of ES decay and an end state of low wave number Langmuir/z-mode waves with strong electric fields perpendicular to the magnetic field. For many of the split spectral-peak events, an intense low-frequency response occurs that is consistent with ion-acoustic waves produced by ES decay, providing further evidence that these events are ES decay. An observed event is shown to be consistent with three successive backscatter decays, but such events are very rare in type III bursts. About 90% of the split spectral-peak events occur when T-i/T-e less than or similar to 0.6. Similarly, over 80% of the split peak events have energy densities above the theoretical nonlinear threshold for ES decay (for reasonable Langmuir damping rates less than or similar to 10(p)(-3)). All events have beam speeds and energy densities below the maxima appropriate for ES decay of beam-driven Langmuir waves.

  • 20.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Cairns, Iver H.
    The Langmuir waves associated with the 1 December 2013 type II burst2015In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 120, no 6, p. 4126-4141Article in journal (Refereed)
    Abstract [en]

    The Langmuir waves associated with an interplanetary type II source region are presented. The type II burst was first observed on 29 November 2013 by STEREO A and B, with the shock crossing STEREO A on 1 December 2013. In the foreshock region upstream of the shock, 11 Langmuir-like waveforms were recorded by STEREO A's Time Domain Sampler on three orthogonal antennas. The observed Langmuir wave electric fields are of large amplitude and aligned with the background magnetic field. Some of the waveforms show evidence of electrostatic decay, and several are consistent with Langmuir eigenmodes of density wells. Harmonic electric fields are observed simultaneously with the Langmuir waveforms and are consistent with fields produced by nonlinear currents. The beam speeds v(b) exciting the Langmuir waves are estimated from the waveform data, yielding speeds v(b) approximate to(0.01-0.04)c. These are consistent with previous observations. The beam speeds are slower than those associated with type III solar radio bursts, consistent with the Langmuir wave electric fields being field aligned. The evidence found for electrostatic decay and against strong perpendicular fields, and so low-wave number Langmuir/z-mode waves, suggests that the dominant emission mechanisms for this type II foreshock involve electrostatic decay and nonlinear wave processes, rather than linear-mode conversion. Harmonic radio emission via antenna mechanisms involving Langmuir waves remains possible.

  • 21.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Cairns, Iver H.
    Malaspina, D. M.
    Harmonic waves and sheath rectification in type III solar radio bursts2014In: J GEOPHYS RES-SPACE, ISSN 2169-9380, Vol. 119, no 2, p. 723-741Article in journal (Refereed)
    Abstract [en]

    In type III solar radio bursts and planetary foreshocks, Langmuir waves are produced by electron beams and converted partially to radio waves by linear and nonlinear processes. Lower amplitude second harmonic electric fields are observed simultaneously during the most intense Langmuir wave events in type III source regions. The electric fields at the harmonic frequencies can arise from various mechanisms, such as radio wave emission by either coalescence or antenna mechanisms, nonlinear currents, harmonics of Langmuir waves, electron trapping in Langmuir wave potentials, and Langmuir wave rectification at the sheath surrounding the spacecraft, or they can result from instrumental harmonics. In this paper the relative powers and electric field vectors of Langmuir waves and the harmonic fields are compared for multiple events. The structure of the harmonic field is shown to be determined by the Langmuir waveform, but the harmonic field direction is typically closely aligned with the solar wind flow. The magnitude, structure, and orientation of the harmonic fields is used to determine which processes are responsible. It is shown that the dominant process generating the observed harmonic fields is Langmuir wave rectification at the sheath surrounding the spacecraft. Key Points <list list-type="bulleted"> <list-item id="jgra50855-li-0001">Intense Langmuir waves and harmonic fields are observed simultaneously <list-item id="jgra50855-li-0002">Harmonic fields are primarily produced by sheath rectification <list-item id="jgra50855-li-0003">Some evidence for nonlinear currents is found

  • 22.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Cairns, Iver H.
    Robinson, P. A.
    Langmuir "snakes" and electrostatic decay in the solar wind2013In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 40, no 10, p. 1934-1939Article in journal (Refereed)
    Abstract [en]

    When Langmuir waves are driven by an electron beam to large amplitudes, they can undergo electrostatic (ES) decay to smaller wave numbers via a series of backscatters. Truncated ES decay, where the number of backscatters is reduced due to damping, is modeled here using the three-dimensional ES Zakharov equations. Langmuir beats develop in snake-like structures parallel to the electron beam direction and are most evident when decay is truncated to a single backscatter. From these results, an analytic form is derived and shown to be consistent with some of the waveforms and spectra observed by STEREO in the source regions of type III solar radio bursts. The agreement between the model and observations provides strong evidence for ES decay and Langmuir snakes parallel to the electron beam and so the ambient magnetic field.

  • 23.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Swedish Inst Space Phys, Uppsala, Sweden..
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Norgren, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lindqvist, P. -A
    Marklund, G. T.
    KTH Royal Inst Technol, Sch Elect Engn, Space & Plasma Phys, Stockholm, Sweden..
    Ergun, R. E.
    Univ Colorado, Atmospher & Space Phys Lab, Campus Box 392, Boulder, CO 80309 USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Avanov, L. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Lavraud, B.
    Univ Toulouse UPS, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, Toulouse, France..
    Saito, Y.
    JAXA, Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria..
    Russell, C. T.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria.;Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Strangeway, R. J.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria.;Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Torbert, R. B.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA..
    Burch, J. L.
    SW Res Inst, San Antonio, TX USA..
    Electron currents and heating in the ion diffusion region of asymmetric reconnection2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 10, p. 4691-4700Article in journal (Refereed)
    Abstract [en]

    In this letter the structure of the ion diffusion region of magnetic reconnection at Earth's magnetopause is investigated using the Magnetospheric Multiscale (MMS) spacecraft. The ion diffusion region is characterized by a strong DC electric field, approximately equal to the Hall electric field, intense currents, and electron heating parallel to the background magnetic field. Current structures well below ion spatial scales are resolved, and the electron motion associated with lower hybrid drift waves is shown to contribute significantly to the total current density. The electron heating is shown to be consistent with large-scale parallel electric fields trapping and accelerating electrons, rather than wave-particle interactions. These results show that sub-ion scale processes occur in the ion diffusion region and are important for understanding electron heating and acceleration.

  • 24.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Norgren, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Toledo-Redondo, S.
    European Space Agcy ESAC, Madrid, Spain..
    Lindqvist, P. -A
    Marklund, G. T.
    KTH Royal Inst Technol, Sch Elect Engn, Space & Plasma Phys, Stockholm, Sweden..
    Ergun, R. E.
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, Dept Astron, College Pk, MD USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Avanov, L. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, Dept Astron, College Pk, MD USA..
    Lavraud, B.
    Univ Toulouse UPS, Inst Rech Astrophys & Plantol, Toulouse, France.;Ctr Natl Rech Sci, Toulouse, France..
    Saito, Y.
    JAXA, Inst Space & Aeronaut Sci, Sagamihara, Kanagawa, Japan..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA USA..
    Strangeway, R. J.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA USA..
    Torbert, R. B.
    Univ New Hampshire, Ctr Space Sci, Durham, NH USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Lower hybrid waves in the ion diffusion and magnetospheric inflow regions2017In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 122, no 1, p. 517-533Article in journal (Refereed)
    Abstract [en]

    The role and properties of lower hybrid waves in the ion diffusion region and magnetospheric inflow region of asymmetric reconnection are investigated using the Magnetospheric Multiscale (MMS) mission. Two distinct groups of lower hybrid waves are observed in the ion diffusion region and magnetospheric inflow region, which have distinct properties and propagate in opposite directions along the magnetopause. One group develops near the ion edge in the magnetospheric inflow, where magnetosheath ions enter the magnetosphere through the finite gyroradius effect and are driven by the ion-ion cross-field instability due to the interaction between the magnetosheath ions and cold magnetospheric ions. This leads to heating of the cold magnetospheric ions. The second group develops at the sharpest density gradient, where the Hall electric field is observed and is driven by the lower hybrid drift instability. These drift waves produce cross-field particle diffusion, enabling magnetosheath electrons to enter the magnetospheric inflow region thereby broadening the density gradient in the ion diffusion region.

  • 25.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Andre, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Electrostatic solitary waves and electrostatic waves at the magnetopause2016In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 121, no 4, p. 3069-3092Article in journal (Refereed)
    Abstract [en]

    Electrostatic solitary waves (ESWs) are characterized by localized bipolar electric fields parallel to the magnetic field and are frequently observed in space plasmas. In this paper a study of ESWs and field-aligned electrostatic waves, which do not exhibit localized bipolar fields, near the magnetopause is presented using the Cluster spacecraft. The speeds, length scales, field strengths, and potentials are calculated and compared with the local plasma conditions. A large range of speeds is observed, suggesting different generation mechanisms. In contrast, a smaller range of length scales normalized to the Debye length lambda(D) is found. For ESWs the average length between the positive and negative peak fields is 9 lambda(D), comparable to the average half wavelength of electrostatic waves. Statistically, the lengths and speeds of ESWs and electrostatic waves are shown to be similar. The length scales and potentials of the ESWs are consistent with predictions for stable electron holes. The maximum ESW potentials are shown to be constrained by the length scale and the magnetic field strength at the magnetopause and in the magnetosheath. The observed waves are consistent with those generated by the warm bistreaming instability, beam-plasma instability, and electron-ion instabilities, which account for the observed speeds and length scales. The large range of wave speeds suggests that the waves can couple different electron populations and electrons with ions, heating the plasma and contributing to anomalous resistivity.

  • 26.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Electrostatic solitary waves with distinct speeds associated with asymmetric reconnection2015In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, no 2, p. 215-224Article in journal (Refereed)
    Abstract [en]

    Electrostatic solitary waves (ESWs) are observed at the magnetopause with distinct time scales. These ESWs are associated with asymmetric reconnection of the cold dense magnetosheath plasma with the hot tenuous magnetospheric plasma. The distinct time scales are shown to be due to ESWs moving at distinct speeds and having distinct length scales. The length scales are of order 5-50 Debye lengths, and the speeds range from approximate to 50 km s(-1) to approximate to 1000 km s(-1). The ESWs are observed near the reconnection separatrices. The observation of ESWs with distinct speeds suggests that multiple instabilities are occurring. The implications for reconnection at the magnetopause are discussed.

  • 27.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fazakerley, A. N.
    Electron Dynamics in the Diffusion Region of an Asymmetric Magnetic Reconnection2014In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 112, no 21, p. 215004-Article in journal (Refereed)
    Abstract [en]

    During a magnetopause crossing near the subsolar point Cluster observes the ion diffusion region of antiparallel magnetic reconnection. The reconnecting plasmas are asymmetric, differing in magnetic field strength, density, and temperature. Spatial changes in the electron distributions in the diffusion region are resolved and investigated in detail. Heating of magnetosheath electrons parallel to the magnetic field is observed. This heating is shown to be consistent with trapping of magnetosheath electrons by parallel electric fields.

  • 28.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Norgren, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Webster, J. M.
    Rice Univ, Dept Phys & Astron, Houston, TX 77005 USA.
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Lindqvist, P. -A
    Space and Plasma Physics, School of Electrical Engineering, KTH Royal Institute of Technology, Stockholm SE-11428, Sweden.
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80303 USA.
    Torbert, R. B.
    Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA.
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Gershman, D. J.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA;NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, A-8042 Graz, Austria.
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA.
    Instability of Agyrotropic Electron Beams near the Electron Diffusion Region2017In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 119, no 2, article id 025101Article in journal (Refereed)
    Abstract [en]

    During a magnetopause crossing the Magnetospheric Multiscale spacecraft encountered an electron diffusion region (EDR) of asymmetric reconnection. The EDR is characterized by agyrotropic beam and crescent electron distributions perpendicular to the magnetic field. Intense upper-hybrid (UH) waves are found at the boundary between the EDR and magnetosheath inflow region. The UH waves are generated by the agyrotropic electron beams. The UH waves are sufficiently large to contribute to electron diffusion and scattering, and are a potential source of radio emission near the EDR. These results provide observational evidence of wave-particle interactions at an EDR, and suggest that waves play an important role in determining the electron dynamics.

  • 29.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Malaspina, D. M.
    Cairns, Iver H.
    Applying bicoherence analysis to spacecraft observations of Langmuir waves2014In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 41, no 5, p. 1367-1374Article in journal (Refereed)
    Abstract [en]

    In type II and type III solar radio bursts and planetary foreshocks, the processes which convert Langmuir waves (LWs) to transverse waves are not well understood. One of the proposed mechanisms for generating transverse waves involves electrostatic (ES) decay followed by coalescence of two LWs. One of the tests used to identify this process is bicoherence analysis. Bicoherence has been applied to spacecraft observations of LWs to yield results consistent with ES decay and coalescence. However, recent work has shown that the harmonic fields produced by LWs are more consistent with sheath rectification and nonlinear currents. It is shown here that sheath rectification and nonlinear currents yield bicoherences similar to those expected for ES decay and coalescence, explaining the bicoherences associated with spacecraft observations of LWs. These results show that bicoherence alone cannot be used to identify ES decay and coalescence and emphasize the importance of sheath rectification. Key Points <list list-type="bulleted"> <list-item id="grl51444-li-0001">Sheath rectification and nonlinear currents produce phase-coherent fields <list-item id="grl51444-li-0002">Bicoherences are consistent with nonlinear currents and sheath rectification <list-item id="grl51444-li-0003">Bicoherence cannot identify electrostatic decay and coalescence

  • 30.
    Graham, Daniel. B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri. V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Swedish Inst Space Phys, Uppsala, Sweden..
    Andre, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Whistler emission in the separatrix regions of asymmetric magnetic reconnection2016In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 121, no 3, p. 1934-1954Article in journal (Refereed)
    Abstract [en]

    At Earth's dayside magnetopause asymmetric magnetic reconnection occurs between the cold dense magnetosheath plasma and the hot tenuous magnetospheric plasma, which differs significantly from symmetric reconnection. During magnetic reconnection the separatrix regions are potentially unstable to a variety of instabilities. In this paper observations of the separatrix regions of asymmetric reconnection are reported as Cluster crossed the magnetopause near the subsolar point. The small relative motion between the spacecraft and plasma allows spatial changes of electron distributions within the separatrix regions to be resolved over multiple spacecraft spins. The electron distributions are shown to be unstable to the electromagnetic whistler mode and the electrostatic beam mode. Large-amplitude whistler waves are observed in the magnetospheric and magnetosheath separatrix regions, and outflow region. In the magnetospheric separatrix regions the observed whistler waves propagate toward the X line, which are shown to be driven by the loss in magnetospheric electrons propagating away from the X line and are enhanced by the presence of magnetosheath electrons. The beam mode waves are predicted to be produced by beams of magnetosheath electrons propagating away from the X line and potentially account for some of the electrostatic fluctuations observed in the magnetospheric separatrix regions.

  • 31.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Le Contel, O.
    Univ Paris Sud, UPMC Univ Paris 06, Observ Paris, LPP,UMR7648,CNRS,Ecole Polytech, Paris, France.
    Malaspina, D. M.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Lindqvist, P. -A
    Wilder, F. D.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA;Univ Maryland, Dept Astron, College Pk, MD 20742 USA.
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA.
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA.
    Torbert, R. B.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.
    Large-Amplitude High-Frequency Waves at Earth's Magnetopause2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 4, p. 2630-2657Article in journal (Refereed)
    Abstract [en]

    Large-amplitude waves near the electron plasma frequency are found by the Magnetospheric Multiscale (MMS) mission near Earth's magnetopause. The waves are identified as Langmuir and upper hybrid (UH) waves, with wave vectors either close to parallel or close to perpendicular to the background magnetic field. The waves are found all along the magnetopause equatorial plane, including both flanks and close to the subsolar point. The waves reach very large amplitudes, up to 1Vm(-1), and are thus among the most intense electric fields observed at Earth's magnetopause. In the magnetosphere and on the magnetospheric side of the magnetopause the waves are predominantly UH waves although Langmuir waves are also found. When the plasma is very weakly magnetized only Langmuir waves are likely to be found. Both Langmuir and UH waves are shown to have electromagnetic components, which are consistent with predictions from kinetic wave theory. These results show that the magnetopause and magnetosphere are often unstable to intense wave activity near the electron plasma frequency. These waves provide a possible source of radio emission at the magnetopause.

  • 32.
    Graham, Daniel B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Eriksson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Malaspina, D. M.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Lindqvist, P-A
    KTH Royal Inst Technol, Sch Elect Engn, Space & Plasma Phys, Stockholm, Sweden.
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA;Univ Maryland, Dept Astron, College Pk, MD 20742 USA.
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.
    Enhanced Escape of Spacecraft Photoelectrons Caused by Langmuir and Upper Hybrid Waves2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 9, p. 7534-7553Article in journal (Refereed)
    Abstract [en]

    The spacecraft potential is often used to infer rapid changes in the thermal plasma density. The variations in spacecraft potential associated with large-amplitude Langmuir and upper hybrid waves are investigated with the Magnetospheric Multiscale (MMS) mission. When large-amplitude Langmuir and upper hybrid waves are observed, the spacecraft potential increases. The changes in spacecraft potential are shown to be due to enhanced photoelectron escape from the spacecraft when the wave electric fields reach large amplitude. The fluctuations in spacecraft potential follow the envelope function of the Langmuir and upper hybrid waves. Comparison with the high-resolution electron moments shows that the changes in spacecraft potential associated with the waves are not due to density perturbations. Indeed, using the spacecraft potential as a density probe leads to unphysically large density fluctuations. In addition, the changes in spacecraft potential are shown to increase as density decreases: larger spacecraft potential changes are observed in the magnetosphere, than in the magnetosheath and solar wind. These results show that external electric fields can lead to unphysical results when the spacecraft potential is used as a density probe. The results suggest that fluctuations in the spacecraft potential alone cannot be used to determine whether nonlinear processes associated with Langmuir and upper hybrid waves, such as the ponderomotive force and three-wave decay, are occurring.

  • 33.
    Huang, S. Y.
    et al.
    Wuhan Univ, Sch Elect Informat, Wuhan, Peoples R China.;UPMC, Lab Phys Plasmas, CNRS, Ecole Polytech, Palaiseau, France..
    Fu, H. S.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China..
    Yuan, Z. G.
    Wuhan Univ, Sch Elect Informat, Wuhan, Peoples R China..
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Retino, A.
    UPMC, Lab Phys Plasmas, CNRS, Ecole Polytech, Palaiseau, France..
    Zhou, M.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang, Peoples R China..
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fujimoto, K.
    Natl Astron Observ Japan, Div Theoret Astron, Mitaka, Tokyo, Japan..
    Sahraoui, F.
    UPMC, Lab Phys Plasmas, CNRS, Ecole Polytech, Palaiseau, France..
    Deng, X. H.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang, Peoples R China..
    Ni, B.
    Wuhan Univ, Sch Elect Informat, Wuhan, Peoples R China..
    Pang, Y.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang, Peoples R China..
    Fu, S.
    Wuhan Univ, Sch Elect Informat, Wuhan, Peoples R China..
    Wang, D. D.
    Wuhan Univ, Sch Elect Informat, Wuhan, Peoples R China..
    Zhou, X.
    Liaoning Univ, Sch Phys, Shenyang, Peoples R China..
    Two types of whistler waves in the hall reconnection region2016In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 121, no 7, p. 6639-6646Article in journal (Refereed)
    Abstract [en]

    Whistler waves are believed to play an important role during magnetic reconnection. Here we report the near-simultaneous occurrence of two types of the whistler-mode waves in the magnetotail Hall reconnection region. The first type is observed in the magnetic pileup region of downstream and propagates away to downstream along the field lines and is possibly generated by the electron temperature anisotropy at the magnetic equator. The second type, propagating toward the X line, is found around the separatrix region and probably is generated by the electron beam-driven whistler instability or erenkov emission from electron phase-space holes. These observations of two different types of whistler waves are consistent with recent kinetic simulations and suggest that the observed whistler waves are a consequence of magnetic reconnection.

  • 34.
    Huang, S. Y.
    et al.
    Wuhan Univ, Sch Elect Informat, Wuhan, Hubei, Peoples R China.
    Yuan, Z. G.
    Wuhan Univ, Sch Elect Informat, Wuhan, Hubei, Peoples R China.
    Fu, H. S.
    Beihang Univ, Sch Astronaut, Space Sci Inst, Beijing, Peoples R China.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Sahraoui, F.
    UPMC, EcolePolytech, CNRS, Lab Phys Plasmas, Palaiseau, France.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Retino, A.
    UPMC, EcolePolytech, CNRS, Lab Phys Plasmas, Palaiseau, France.
    Zhou, M.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang, Jiangxi, Peoples R China.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fujimoto, K.
    Natl Astron Observ Japan, Div Theoret Astron, Mitaka, Tokyo, Japan.
    Deng, X. H.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang, Jiangxi, Peoples R China.
    Ni, B. B.
    Wuhan Univ, Sch Elect Informat, Wuhan, Hubei, Peoples R China.
    Pang, Y.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang, Jiangxi, Peoples R China.
    Fu, S.
    Wuhan Univ, Sch Elect Informat, Wuhan, Hubei, Peoples R China.
    Wang, D. D.
    Wuhan Univ, Sch Elect Informat, Wuhan, Hubei, Peoples R China.
    Observations of Whistler Waves in the Magnetic Reconnection Diffusion Region2018In: 2ND URSI ATLANTIC RADIO SCIENCE MEETING (AT-RASC), IEEE , 2018Conference paper (Refereed)
    Abstract [en]

    Whistler waves are believed to play an important role during magnetic reconnection. In this paper, we report the simultaneous occurrence of two types of the whistler waves in the magnetotail reconnection diffusion region. The first type is observed in the pileup region of downstream and propagates away along the field lines to downstream, and is possibly generated by the electron temperature anisotropy at the magnetic equator. The second type is found around the separatrix region and propagates towards the X-line, and is possibly aenerated by the electron beam-driven whistler instability or Cerenkov emission from electron phase-space holes. Our observations of two different types of whistler waves are well consistent with recent kinetic simulations, and suggest that the observed whistler waves are the consequences of magnetic reconnection.Moreover, we statistically investigate the whistler waves in the magnetotail reconnection region, and construct the global distribution and occurrence rate of the whistler waves based on the two-dimensional reconnection model. It is found that the occurrence rate of the whistler waves is large in the separatrix region (113,1B0j>0.4) and pileup region ([B,./Bol<0.2, 161>45'), but very small in the X-line region. The statistical results are well consistent with the case study.

  • 35.
    Kacem, I.
    et al.
    Univ Toulouse, CNES, UPS, Inst Rech Astrophys & Planetol,CNRS, Toulouse, France.
    Jacquey, C.
    Univ Toulouse, CNES, UPS, Inst Rech Astrophys & Planetol,CNRS, Toulouse, France.
    Genot, V.
    Univ Toulouse, CNES, UPS, Inst Rech Astrophys & Planetol,CNRS, Toulouse, France.
    Lavraud, B.
    Univ Toulouse, CNES, UPS, Inst Rech Astrophys & Planetol,CNRS, Toulouse, France.
    Vernisse, Y.
    Univ Toulouse, CNES, UPS, Inst Rech Astrophys & Planetol,CNRS, Toulouse, France.
    Marchaudon, A.
    Univ Toulouse, CNES, UPS, Inst Rech Astrophys & Planetol,CNRS, Toulouse, France.
    Le Contel, O.
    Lab Phys Plasmas, Palaiseau, France.
    Breuillard, H.
    Lab Phys Plasmas, Palaiseau, France.
    Phan, T. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA.
    Hasegawa, H.
    JAXA, Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan.
    Oka, M.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA.
    Trattner, K. J.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Farrugia, C. J.
    Univ New Hampshire, Phys Dept, Durham, NH 03824 USA;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA.
    Paulson, K.
    Univ New Hampshire, Phys Dept, Durham, NH 03824 USA;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA.
    Eastwood, J. P.
    Imperial Coll London, Dept Phys, Blackett Lab, London, England.
    Fuselier, S. A.
    Southwest Res Inst, San Antonio, TX USA;Univ Texas San Antonio, Dept Phys, San Antonio, TX USA.
    Turner, D.
    Aerosp Corp, Space Sci Dept, El Segundo, CA 90245 USA.
    Eriksson, S.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Wilder, F.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Russell, C. T.
    Univ Calif Los Angeles, Inst Geophys Earth Planetary & Space Sci, Los Angeles, CA USA.
    Oieroset, M.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA.
    Burch, J.
    Southwest Res Inst, San Antonio, TX USA.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Sauvaud, J-A
    Avanov, L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Chandler, M.
    NASA, Marshall Space Flight Ctr, Huntsville, AL USA.
    Coffey, V.
    NASA, Marshall Space Flight Ctr, Huntsville, AL USA.
    Dorelli, J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Moore, T. E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Saito, Y.
    JAXA, Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan.
    Chen, L-J
    Penou, E.
    Univ Toulouse, CNES, UPS, Inst Rech Astrophys & Planetol,CNRS, Toulouse, France.
    Magnetic Reconnection at a Thin Current Sheet Separating Two Interlaced Flux Tubes at the Earth's Magnetopause2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 3, p. 1779-1793Article in journal (Refereed)
    Abstract [en]

    The occurrence of spatially and temporally variable reconnection at the Earth's magnetopause leads to the complex interaction of magnetic fields from the magnetosphere and magnetosheath. Flux transfer events (FTEs) constitute one such type of interaction. Their main characteristics are (1) an enhanced core magnetic field magnitude and (2) a bipolar magnetic field signature in the component normal to the magnetopause, reminiscent of a large-scale helicoidal flux tube magnetic configuration. However, other geometrical configurations which do not fit this classical picture have also been observed. Using high-resolution measurements from the Magnetospheric Multiscale mission, we investigate an event in the vicinity of the Earth's magnetopause on 7 November 2015. Despite signatures that, at first glance, appear consistent with a classic FTE, based on detailed geometrical and dynamical analyses as well as on topological signatures revealed by suprathermal electron properties, we demonstrate that this event is not consistent with a single, homogenous helicoidal structure. Our analysis rather suggests that it consists of the interaction of two separate sets of magnetic field lines with different connectivities. This complex three-dimensional interaction constructively conspires to produce signatures partially consistent with that of an FTE. We also show that, at the interface between the two sets of field lines, where the observed magnetic pileup occurs, a thin and strong current sheet forms with a large ion jet, which may be consistent with magnetic flux dissipation through magnetic reconnection in the interaction region.

  • 36.
    Khotyaintsev, Yuri V.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, D. B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Norgren, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Eriksson, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Li, Wenya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Johlander, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Andre, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Pritchett, P. L.
    Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA USA..
    Retino, A.
    CNRS, LPP, Palaiseau, France..
    Phan, T. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Goodrich, K.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Lindqvist, P. -A
    Marklund, G. T.
    KTH Royal Inst Technol, Stockholm, Sweden..
    Le Contel, O.
    CNRS, LPP, Palaiseau, France..
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Strangeway, R. J.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Vaith, H.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA..
    Argall, M. R.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA..
    Kletzing, C. A.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Torbert, R. B.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Avanov, L. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Lavraud, B.
    CNRS, IRAP, Toulouse, France..
    Saito, Y.
    JAXA, Chofu, Tokyo, Japan..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Turner, D. L.
    Aerosp Corp, Dept Space Sci, El Segundo, CA 90245 USA..
    Blake, J. D.
    Aerosp Corp, Dept Space Sci, El Segundo, CA 90245 USA..
    Fennell, J. F.
    Aerosp Corp, Dept Space Sci, El Segundo, CA 90245 USA..
    Jaynes, A.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Mauk, B. H.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Electron jet of asymmetric reconnection2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 11, p. 5571-5580Article in journal (Refereed)
    Abstract [en]

    We present Magnetospheric Multiscale observations of an electron-scale current sheet and electron outflow jet for asymmetric reconnection with guide field at the subsolar magnetopause. The electron jet observed within the reconnection region has an electron Mach number of 0.35 and is associated with electron agyrotropy. The jet is unstable to an electrostatic instability which generates intense waves with E-vertical bar amplitudes reaching up to 300mVm(-1) and potentials up to 20% of the electron thermal energy. We see evidence of interaction between the waves and the electron beam, leading to quick thermalization of the beam and stabilization of the instability. The wave phase speed is comparable to the ion thermal speed, suggesting that the instability is of Buneman type, and therefore introduces electron-ion drag and leads to braking of the electron flow. Our observations demonstrate that electrostatic turbulence plays an important role in the electron-scale physics of asymmetric reconnection.

  • 37.
    Khotyaintsev, Yuri V.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Norgren, Cecilia
    Univ Bergen, Dept Phys & Technol, Bergen, Norway.
    Vaivads, Andris
    KTH Royal Inst Technol, Dept Space & Plasma Phys, Stockholm, Sweden.
    Collisionless Magnetic Reconnection and Waves: Progress Review2019In: FRONTIERS IN ASTRONOMY AND SPACE SCIENCES, ISSN 2296-987X, Vol. 6, article id 70Article, review/survey (Refereed)
    Abstract [en]

    Magnetic reconnection is a fundamental process whereby microscopic plasma processes cause macroscopic changes in magnetic field topology, leading to explosive energy release. Waves and turbulence generated during the reconnection process can produce particle diffusion and anomalous resistivity, as well as heat the plasma and accelerate plasma particles, all of which can impact the reconnection process. We review progress on waves related to reconnection achieved using high resolution multi-point in situ observations over the last decade, since early Cluster and THEMIS observations and ending with recent Magnetospheric Multiscale results. In particular, we focus on the waves most frequently observed in relation to reconnection, ranging from low-frequency kinetic Alfven waves (KAW), to intermediate frequency lower hybrid and whistler-mode waves, electrostatic broadband and solitary waves, as well as the high-frequency upper hybrid, Langmuir, and electron Bernstein waves. Significant progress has been made in understanding localization of the different wave modes in the context of the reconnection picture, better quantification of generation mechanisms and wave-particle interactions, including anomalous resistivity. Examples include: temperature anisotropy driven whistlers in the flux pileup region, anomalous effects due to lower-hybrid waves, upper hybrid wave generation within the electron diffusion region, wave-particle interaction of electrostatic solitary waves. While being clearly identified in observations, some of the wave processes remain challenging for reconnection simulations (electron Bernstein, upper hybrid, Langmuir, whistler), as the instabilities (streaming, loss-cone, shell) which drive these waves require high resolution of distribution functions in phase space, and realistic ratio of Debye to electron inertia scales. We discuss how reconnection configuration, i.e., symmetric vs. asymmetric, guide-field vs. antiparallel, affect wave occurrence, generation, effect on particles, and feedback on the overall reconnection process. Finally, we outline some of the major open questions, such as generation of electromagnetic radiation by reconnection sites and role of waves in triggering/onset of reconnection.

  • 38.
    Lavraud, B.
    et al.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France..
    Zhang, Y. C.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France.;CAS, NSSC, State Key Lab Space Weather, Beijing, Peoples R China..
    Vernisse, Y.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Dorelli, J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Cassak, P. A.
    W Virginia Univ, Dept Phys & Astron, Morgantown, WV 26506 USA..
    Dargent, J.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France.;Plasma Phys Lab, Palaiseau, France..
    Pollock, C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Giles, B.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Aunai, N.
    Plasma Phys Lab, Palaiseau, France..
    Argall, M.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Avanov, L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Barrie, A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Millenium Engn & Integrat Co, Arlington, VA USA..
    Burch, J.
    SW Res Inst, San Antonio, TX USA..
    Chandler, M.
    NASA, Marshall Space Flight Ctr, Huntsville, AL USA..
    Chen, L. -J
    Clark, G.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Cohen, I.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Coffey, V.
    NASA, Marshall Space Flight Ctr, Huntsville, AL USA..
    Eastwood, J. P.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London, England..
    Egedal, J.
    Univ Wisconsin, Dept Phys, 1150 Univ Ave, Madison, WI 53706 USA..
    Eriksson, S.
    Univ Colorado, Atmospher & Space Phys Lab, Campus Box 392, Boulder, CO 80309 USA..
    Ergun, R.
    Univ Colorado, Atmospher & Space Phys Lab, Campus Box 392, Boulder, CO 80309 USA..
    Farrugia, C. J.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Fuselier, S. A.
    SW Res Inst, San Antonio, TX USA..
    Genot, V.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France..
    Graham, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Grigorenko, E.
    Russian Acad Sci, Space Res Inst, Moscow, Russia..
    Hasegawa, H.
    JAXA, Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan..
    Jacquey, C.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France..
    Kacem, I.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France..
    Khotyaintsev, Yuri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    MacDonald, E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria..
    Marchaudon, A.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France..
    Mauk, B.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Moore, T. E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Mukai, T.
    JAXA, Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria..
    Paterson, W.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Penou, E.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France..
    Phan, T. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Rager, A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA..
    Retino, A.
    Plasma Phys Lab, Palaiseau, France..
    Rong, Z. J.
    CAS, IGG, Key Lab Earth & Planetary Phys, Beijing, Peoples R China..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Saito, Y.
    JAXA, Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan..
    Sauvaud, J. -A
    Schwartz, S. J.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London, England.;Univ Colorado, Atmospher & Space Phys Lab, Campus Box 392, Boulder, CO 80309 USA..
    Shen, C.
    Harbin Inst Technol, Shenzhen, Peoples R China..
    Smith, S.
    Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA..
    Strangeway, R.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Toledo-Redondo, S.
    ESAC ESA, Villafranca Del Castillo, Spain..
    Torbert, R.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Turner, D. L.
    Aerosp Corp, El Segundo, CA 90245 USA..
    Wang, S.
    Millenium Engn & Integrat Co, Arlington, VA USA..
    Yokota, S.
    JAXA, Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan..
    Currents and associated electron scattering and bouncing near the diffusion region at Earth's magnetopause2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 7, p. 3042-3050Article in journal (Refereed)
    Abstract [en]

    Based on high-resolution measurements from NASA's Magnetospheric Multiscale mission, we present the dynamics of electrons associated with current systems observed near the diffusion region of magnetic reconnection at Earth's magnetopause. Using pitch angle distributions (PAD) and magnetic curvature analysis, we demonstrate the occurrence of electron scattering in the curved magnetic field of the diffusion region down to energies of 20 eV. We show that scattering occurs closer to the current sheet as the electron energy decreases. The scattering of inflowing electrons, associated with field-aligned electrostatic potentials and Hall currents, produces a new population of scattered electrons with broader PAD which bounce back and forth in the exhaust. Except at the center of the diffusion region the two populations are collocated and appear to behave adiabatically: the inflowing electron PAD focuses inward (toward lower magnetic field), while the bouncing population PAD gradually peaks at 90 degrees away from the center (where it mirrors owing to higher magnetic field and probable field-aligned potentials).

  • 39.
    Le Contel, O.
    et al.
    Univ Paris Sud, Univ Paris 06, UPMC, Lab Phys Plasmas,UMR7648,CNRS,Ecole Polytech, Paris, France..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Breuillard, H.
    Univ Paris Sud, Univ Paris 06, UPMC, Lab Phys Plasmas,UMR7648,CNRS,Ecole Polytech, Paris, France..
    Argall, M. R.
    Univ New Hampshire, Phys Dept, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fischer, D.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Retino, A.
    Univ Paris Sud, Univ Paris 06, UPMC, Lab Phys Plasmas,UMR7648,CNRS,Ecole Polytech, Paris, France..
    Berthomier, M.
    Univ Paris Sud, Univ Paris 06, UPMC, Lab Phys Plasmas,UMR7648,CNRS,Ecole Polytech, Paris, France..
    Pottelette, R.
    Univ Paris Sud, Univ Paris 06, UPMC, Lab Phys Plasmas,UMR7648,CNRS,Ecole Polytech, Paris, France..
    Mirioni, L.
    Univ Paris Sud, Univ Paris 06, UPMC, Lab Phys Plasmas,UMR7648,CNRS,Ecole Polytech, Paris, France..
    Chust, T.
    Univ Paris Sud, Univ Paris 06, UPMC, Lab Phys Plasmas,UMR7648,CNRS,Ecole Polytech, Paris, France..
    Wilder, F. D.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Varsani, A.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Lindqvist, P. -A
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Norgren, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Goodrich, K. A.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Torbert, R. B.
    Univ New Hampshire, Phys Dept, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Needell, J.
    Univ New Hampshire, Phys Dept, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Chutter, M.
    Univ New Hampshire, Phys Dept, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Rau, D.
    Univ New Hampshire, Phys Dept, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Dors, I.
    Univ New Hampshire, Phys Dept, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Strangeway, R. J.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Bromund, K. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Wei, H. Y.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Anderson, B. J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Le, G.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Moore, T. E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Avanov, L. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Saito, Y.
    Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan..
    Lavraud, B.
    Univ Paul Sabatier, CNRS UMR5277, Inst Rech Astrophys & Planetol, Toulouse, France..
    Fuselier, S. A.
    Southwest Res Inst, San Antonio, TX USA..
    Mauk, B. H.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Cohen, I. J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Turner, D. L.
    Aerosp Corp, Space Sci Dept, El Segundo, CA 90245 USA..
    Fennell, J. F.
    Aerosp Corp, Space Sci Dept, El Segundo, CA 90245 USA..
    Leonard, T.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Jaynes, A. N.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Lower Hybrid Drift Waves and Electromagnetic Electron Space-Phase Holes Associated With Dipolarization Fronts and Field-Aligned Currents Observed by the Magnetospheric Multiscale Mission During a Substorm2017In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 122, no 12, p. 12236-12257Article in journal (Refereed)
    Abstract [en]

    We analyze two ion scale dipolarization fronts associated with field-aligned currents detected by the Magnetospheric Multiscale mission during a large substorm on 10 August 2016. The first event corresponds to a fast dawnward flow with an antiparallel current and could be generated by the wake of a previous fast earthward flow. It is associated with intense lower hybrid drift waves detected at the front and propagating dawnward with a perpendicular phase speed close to the electric drift and the ion thermal velocity. The second event corresponds to a flow reversal: from southwward/dawnward to northward/duskward associated with a parallel current consistent with a brief expansion of the plasma sheet before the front crossing and with a smaller lower hybrid drift wave activity. Electromagnetic electron phase-space holes are detected near these low-frequency drift waves during both events. The drift waves could accelerate electrons parallel to the magnetic field and produce the parallel electron drift needed to generate the electron holes. Yet we cannot rule out the possibility that the drift waves are produced by the antiparallel current associated with the fast flows, leaving the source for the electron holes unexplained.

  • 40.
    Le Contel, O.
    et al.
    Univ Paris 11, UPMC, CNRS UMR7648, LPP,Observ Paris,Ecole Polytech, Palaiseau, France..
    Retino, A.
    Univ Paris 11, UPMC, CNRS UMR7648, LPP,Observ Paris,Ecole Polytech, Palaiseau, France..
    Breuillard, H.
    Univ Paris 11, UPMC, CNRS UMR7648, LPP,Observ Paris,Ecole Polytech, Palaiseau, France..
    Mirioni, L.
    Univ Paris 11, UPMC, CNRS UMR7648, LPP,Observ Paris,Ecole Polytech, Palaiseau, France..
    Robert, P.
    Univ Paris 11, UPMC, CNRS UMR7648, LPP,Observ Paris,Ecole Polytech, Palaiseau, France..
    Chasapis, A.
    Univ Paris 11, UPMC, CNRS UMR7648, LPP,Observ Paris,Ecole Polytech, Palaiseau, France..
    Lavraud, B.
    Univ Toulouse 3, CNRS UMR5277, IRAP, Toulouse, France..
    Chust, T.
    Univ Paris 11, UPMC, CNRS UMR7648, LPP,Observ Paris,Ecole Polytech, Palaiseau, France..
    Rezeau, L.
    Univ Paris 11, UPMC, CNRS UMR7648, LPP,Observ Paris,Ecole Polytech, Palaiseau, France..
    Wilder, F. D.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Argall, M. R.
    Univ New Hampshire, Durham, NH 03824 USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Lindqvist, P. -A
    Royal Inst Technol, Stockholm, Sweden.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Marklund, G.
    Royal Inst Technol, Stockholm, Sweden..
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Goodrich, K. A.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Torbert, R. B.
    Univ New Hampshire, Durham, NH 03824 USA..
    Needell, J.
    Univ New Hampshire, Durham, NH 03824 USA..
    Chutter, M.
    Univ New Hampshire, Durham, NH 03824 USA..
    Rau, D.
    Univ New Hampshire, Durham, NH 03824 USA..
    Dors, I.
    Univ New Hampshire, Durham, NH 03824 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Los Angeles, CA USA..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Strangeway, R. J.
    Univ Calif Los Angeles, Los Angeles, CA USA..
    Bromund, K. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Leinweber, H. K.
    Univ Calif Los Angeles, Los Angeles, CA USA..
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Fischer, D.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Anderson, B. J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Le, G.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Moore, T. E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Avanov, L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Saito, Y.
    Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan..
    Whistler mode waves and Hall fields detected by MMS during a dayside magnetopause crossing2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 12, p. 5943-5952Article in journal (Refereed)
    Abstract [en]

    We present Magnetospheric Multiscale (MMS) mission measurements during a full magnetopause crossing associated with an enhanced southward ion flow. A quasi-steady magnetospheric whistler mode wave emission propagating toward the reconnection region with quasi-parallel and oblique wave angles is detected just before the opening of the magnetic field lines and the detection of escaping energetic electrons. Its source is likely the perpendicular temperature anisotropy of magnetospheric energetic electrons. In this region, perpendicular and parallel currents as well as the Hall electric field are calculated and found to be consistent with the decoupling of ions from the magnetic field and the crossing of a magnetospheric separatrix region. On the magnetosheath side, Hall electric fields are found smaller as the density is larger but still consistent with the decoupling of ions. Intense quasi-parallel whistler wave emissions are detected propagating both toward and away from the reconnection region in association with a perpendicular anisotropy of the high-energy part of the magnetosheath electron population and a strong perpendicular current, which suggests that in addition to the electron diffusion region, magnetosheath separatrices could be a source region for whistler waves.

  • 41.
    Li, Wenya
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Andre, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Toledo-Redondo, S.
    European Space Agcy, Sci Directorate, ESAC, Madrid, Spain..
    Norgren, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Henri, P.
    CNRS, LPC2E, Orleans, France..
    Wang, C.
    Natl Space Sci Ctr, Beijing, Peoples R China..
    Tang, B. B.
    Natl Space Sci Ctr, Beijing, Peoples R China..
    Lavraud, B.
    Univ Toulouse UPS, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France..
    Vernisse, Y.
    Univ Toulouse UPS, Inst Rech Astrophys & Planetol, Toulouse, France..
    Turner, D. L.
    Aerosp Corp, Dept Space Sci, El Segundo, CA 90245 USA..
    Burch, J.
    Southwest Res Inst, San Antonio, TX USA..
    Torbert, R.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Blake, J. B.
    Aerosp Corp, Dept Space Sci, El Segundo, CA 90245 USA..
    Mauk, B.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Giles, B.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pollock, C.
    Denali Sci, Healy, AL USA..
    Fennell, J.
    Aerosp Corp, Dept Space Sci, El Segundo, CA 90245 USA..
    Jaynes, A.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Avanov, L. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Saito, Y.
    Japan Aerosp Explorat Agcy, Tokyo, Japan..
    Strangeway, R. J.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Kinetic evidence of magnetic reconnection due to Kelvin-Helmholtz waves2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 11, p. 5635-5643Article in journal (Refereed)
    Abstract [en]

    The Kelvin-Helmholtz (KH) instability at the Earth's magnetopause is predominantly excited during northward interplanetary magnetic field (IMF). Magnetic reconnection due to KH waves has been suggested as one of the mechanisms to transfer solar wind plasma into the magnetosphere. We investigate KH waves observed at the magnetopause by the Magnetospheric Multiscale (MMS) mission; in particular, we study the trailing edges of KH waves with Alfvenic ion jets. We observe gradual mixing of magnetospheric and magnetosheath ions at the boundary layer. The magnetospheric electrons with energy up to 80keV are observed on the magnetosheath side of the jets, which indicates that they escape into the magnetosheath through reconnected magnetic field lines. At the same time, the low-energy (below 100eV) magnetosheath electrons enter the magnetosphere and are heated in the field-aligned direction at the high-density edge of the jets. Our observations provide unambiguous kinetic evidence for ongoing reconnection due to KH waves.

  • 42.
    Li, Wenya Y.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fuselier, S. A.
    Southwest Res Inst, San Antonio, TX USA..
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Toledo-Redondo, S.
    European Space Agcy, ESAC, Sci Directorate, Madrid, Spain..
    Lavraud, B.
    Univ Toulouse UPA, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France..
    Turner, D. L.
    Aerosp Corp, Space Sci Dept, El Segundo, CA 90245 USA..
    Norgren, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Tang, B. B.
    Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China..
    Wang, C.
    Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China..
    Lindqvist, P. -A
    Young, D. T.
    Southwest Res Inst, San Antonio, TX USA..
    Chandler, M.
    NASA, Marshall Space Flight Ctr, Huntsville, AL USA..
    Giles, B.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pollock, C.
    Denali Sci, Healy, AK USA..
    Ergun, R.
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Earth Planetary & Space Sci, Los Angeles, CA 90095 USA..
    Torbert, R.
    Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Moore, T.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Burch, J.
    Southwest Res Inst, San Antonio, TX USA..
    Cold Ionospheric Ions in the Magnetic Reconnection Outflow Region2017In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 122, no 10, p. 10194-10202Article in journal (Refereed)
    Abstract [en]

    Magnetosheath plasma usually determines properties of asymmetric magnetic reconnection at the subsolar region of Earth's magnetopause. However, cold plasma that originated from the ionosphere can also reach the magnetopause and modify the kinetic physics of asymmetric reconnection. We present a magnetopause crossing with high-density (10-60 cm(-3)) cold ions and ongoing reconnection from the observation of the Magnetospheric Multiscale (MMS) spacecraft. The magnetopause crossing is estimated to be 300 ion inertial lengths south of the X line. Two distinct ion populations are observed on the magnetosheath edge of the ion jet. One population with high parallel velocities (200-300 km/s) is identified to be cold ion beams, and the other population is the magnetosheath ions. In the deHoffman-Teller frame, the field-aligned magnetosheath ions are Alfvenic and move toward the jet region, while the field-aligned cold ion beams move toward the magnetosheath boundary layer, with much lower speeds. These cold ion beams are suggested to be from the cold ions entering the jet close to the X line. This is the first observation of the cold ionospheric ions in the reconnection outflow region, including the reconnection jet and the magnetosheath boundary layer.

  • 43. Malaspina, David M.
    et al.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Ergun, Robert E.
    Cairns, Iver H.
    Langmuir wave harmonics due to driven nonlinear currents2013In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 118, no 11, p. 6880-6888Article in journal (Refereed)
    Abstract [en]

    The conversion of Langmuir waves into electromagnetic radiation near the local plasma frequency (f(pe)) and twice the local plasma frequency (2f(pe)) occurs in diverse heliospheric environments including along the path of type III radio bursts, at interplanetary shocks, and in planetary foreshocks. This radiation has the potential to act as a probe of remote plasma conditions, provided that the conversion mechanism is well understood. One candidate conversion mechanism is the antenna radiation of localized Langmuir waves. Antenna radiation near 2f(pe) requires the presence of nonlinear currents at 2f(pe). In this work, properties of these currents are predicted from theory and compared with observations of Langmuir wave electric fields made using the WAVES instrument on the STEREO spacecraft. It is found that the observed frequency structure, polarization, and wave number ratio are consistent with nonlinear current predictions, once electric fields near 2f(pe)consistent with sheath effects are taken into account.

  • 44.
    Norgren, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel. B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri. V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Slow electron holes in multicomponent plasmas2015In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, no 18, p. 7264-7272Article in journal (Refereed)
    Abstract [en]

    Electrostatic solitary waves (ESWs), often interpreted as electron phase space holes, are commonly observed in plasmas and are manifestations of strongly nonlinear processes. Often slow ESWs are observed, suggesting generation by the Buneman instability. The instability criteria, however, are generally not satisfied. We show how slow electron holes can be generated by a modified Buneman instability in a plasma that includes a slow electron beam on top of a warm thermal electron background. This lowers the required current for marginal instability and allows for generation of slow electron holes for a wide range of beam parameters that covers expected plasma distributions in space, for example, in magnetic reconnection regions. At higher beam speeds, the electron-electron beam instability becomes dominant instead, producing faster electron holes. The range of phase speeds for this model is consistent with a statistical set of observations at the magnetopause made by Cluster.

  • 45.
    Norgren, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Chen, L. -J
    Lindqvist, P. -A
    Marklund, G. T.
    KTH Royal Inst Technol, Sch Elect Engn, Space & Plasma Phys, Stockholm, Sweden..
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Strangeway, R. J.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA USA..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA USA..
    Torbert, R. B.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Avanov, L. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Lavraud, B.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France..
    Saito, Y.
    Inst Space & Astronaut Sci, JAXA, Sagamihara, Kanagawa, Japan..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Finite gyroradius effects in the electron outflow of asymmetric magnetic reconnection2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 13, p. 6724-6733Article in journal (Refereed)
    Abstract [en]

    We present observations of asymmetric magnetic reconnection showing evidence of electron demagnetization in the electron outflow. The observations were made at the magnetopause by the four Magnetospheric Multiscale (MMS) spacecraft, separated by approximate to 15km. The reconnecting current sheet has negligible guide field, and all four spacecraft likely pass close to the electron diffusion region just south of the X line. In the electron outflow near the X line, all four spacecraft observe highly structured electron distributions in a region comparable to a few electron gyroradii. The distributions consist of a core with T-vertical bar>T and a nongyrotropic crescent perpendicular to the magnetic field. The crescents are associated with finite gyroradius effects of partly demagnetized electrons. These observations clearly demonstrate the manifestation of finite gyroradius effects in an electron-scale reconnection current sheet.

  • 46.
    Norgren, Cecilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Univ Bergen, Birkeland Ctr Space Sci, Dept Phys & Technol, Bergen, Norway.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Swedish Inst Space Phys, Uppsala, Sweden.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Hesse, M.
    Univ Bergen, Birkeland Ctr Space Sci, Dept Phys & Technol, Bergen, Norway.
    Eriksson, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Lindqvist, P-A
    KTH Royal Inst Technol, Sch Elect Engn, Space & Plasma Phys, Stockholm, Sweden.
    Lavraud, B.
    Univ Toulouse, Inst Rech Astrophys & Planetol, CNES, UPS,CNRS, Toulouse, France.
    Burch, J.
    Southwest Res Inst, San Antonio, TX USA.
    Fuselier, S.
    Southwest Res Inst, San Antonio, TX USA;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX USA.
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.
    Gershman, D. J.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA;NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA.
    Electron Reconnection in the Magnetopause Current Layer2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 11, p. 9222-9238Article in journal (Refereed)
    Abstract [en]

    The electron dynamics within thin current sheets plays a key role both for the process of magnetic reconnection and other energy transfer mechanisms but, from an observational point of view, is not well understood. In this paper we report observations of a reconnecting current sheet with intermediate guide field B-G = 0.5B(in), where B-in is the magnetic field amplitude in the inflow regions. The current sheet width is comparable to electron spatial scales. It shows a bifurcated structure and is embedded within the magnetopause current layer with thickness of several ion scales. The electron scale current sheet has strong out-of-plane and in-plane currents, Hall electric and magnetic fields, a finite magnetic field component normal to the current sheet, and nongyrotropic electron distributions formed due to finite gyroradius effects at the boundary of the current sheet. Comparison between test particle simulations and electron data shows that electrons approaching from the edge of the largest magnetic curvature are scattered to perpendicular pitch angles in the center of the current sheet while electrons entering from the opposite side remain close to field aligned. The comparison also shows that an observed depletion in phase space at antiparallel pitch angles can be explained if an out-of-plane electric field, which due to the guide field is close to antiparallel to the magnetic field, is present in the center of the current sheet. This electric field would be consistent with the reconnection electric field, and we therefore interpret the depletion of electron phase space density as a manifestation of ongoing reconnection.

  • 47.
    Pan, Dong-Xiao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Peking Univ, Sch Earth & Space Sci, Beijing, Peoples R Chinä.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Zhou, Xu-Zhi
    Peking Univ, Sch Earth & Space Sci, Beijing, Peoples R China.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lindqvist, Per-Arne
    KTH Royal Inst Technol, Sch Elect Engn, Space & Plasma Phys, Stockholm, Sweden.
    Ergun, Robert E.
    Univ Colorado, Atmospher & Space Phys Lab, Campus Box 392, Boulder, CO 80309 USA.
    Le Contel, Olivier
    Univ Paris Sud, Sorbonne Univ, Lab Phys Plasmas, CNRS,Ecole Polytech,Obs Paris, Paris, France.
    Russell, Christopher T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA.
    Torbert, Roy B.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.
    Giles, Barbara
    NASA Goddard Space Flight Ctr, Greenbelt, MD USA.
    Burch, James L.
    Southwest Res Inst, San Antonio, TX USA.
    Rippled Electron-Scale Structure of a Dipolarization Front2018In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 22, p. 12116-12124Article in journal (Refereed)
    Abstract [en]

    We use the Magnetospheric Multiscale mission to investigate electron-scale structures at a dipolarization front. The four spacecraft are separated by electron scales and observe large differences in plasma and field parameters within the dipolarization front, indicating strong deviation from typically assumed plane or slightly curved front surface. We attribute this to ripples generated by the lower hybrid drift instability (LHDI) with wave number of k(rho e)similar or equal to 0.4 and maximum wave potential of similar to 1 kV similar to k(B)T(e). Power law-like spectra of E-perpendicular to with slope of -3 indicates the turbulent cascade of LHDI. LHDI is observed together with bursty high-frequency parallel electric fields, suggesting coupling of LHDI to higher-frequency electrostatic waves. Plain Language Summary Dipolarization fronts (DFs) are narrow boundaries with sharp enhancement of magnetic field, located at the leading part of fast plasma jets observed in Earth's magnetotail. DFs are typically assumed to be smooth boundaries at scales comparable to the ion gyroradius and below. In this study, we use the four Magnetospheric Multiscale spacecraft separated by several electron gyroradii to investigate fine structure of a DF. Surprisingly, we observe significant differences in the fields and plasma measurements between the spacecraft despite their small separation. We attribute these signatures to electron-scale disturbances propagating along the DF surface, and thus the DF surface is not smooth as expected but rather rippled. The ripples develop as a result of a plasma instability driven by the strong inhomogeneities present at the DF. The fact that the ripples have such small scales means that they can effectively interact with plasma electrons.

  • 48.
    Peng, F. Z.
    et al.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China..
    Fu, H. S.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China..
    Cao, J. B.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China..
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Chen, Z. Z.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China..
    Cao, D.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China..
    Xu, Y.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China..
    Huang, S. Y.
    Wuhan Univ, Sch Elect & Informat, Wuhan, Peoples R China..
    Wang, T. Y.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China..
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Russell, C. T.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Giles, B.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Lindqvist, P. -A
    Torbert, R. B.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.;Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA..
    Ergun, R. E.
    Univ Colorado Boulder, Dept Astrophys & Planetary Sci, Boulder, CO USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Quadrupolar pattern of the asymmetric guide-field reconnection2017In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 122, no 6, p. 6349-6356Article in journal (Refereed)
    Abstract [en]

    With high-resolution data of the recently launched Magnetospheric Multiscale mission, we report a magnetic reconnection event at the dayside magnetopause. This reconnection event, having a density asymmetry N-high/N-low approximate to 2 on the two sides of the reconnecting current sheet and a guide field B-g approximate to 0.4B(0) in the out-of-plane direction, exhibit all the two-fluid features: Alfvenic plasma jets in the outflow region, bipolar Hall electric fields toward the current sheet center, quadrupolar Hall magnetic fields in the out-of-plane direction, and the corresponding Hall currents. Obviously, the density asymmetry N-high/N-low approximate to 2 and the guide field B-g approximate to 0.4B(0) are not sufficient to dismiss the quadrupolar pattern of Hall reconnection. This is different from previous simulations, where the bipolar pattern of Hall reconnection was suggested.

  • 49.
    Steinvall, Konrad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    KTH Royal Inst Technol, Sch Elect Engn & Comp Sci, Div Space & Plasma Phys, S-11428 Stockholm, Sweden.
    Le Contel, Olivier
    Univ Paris Sud, Sorbonne Univ, Observ Paris, Ecole Polytech,Lab Phys Plasmas,CNRS, F-75252 Paris 05, France.
    Russell, Christopher T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA.
    Observations of Electromagnetic Electron Holes and Evidence of Cherenkov Whistler Emission2019In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 123, no 25, article id 255101Article in journal (Refereed)
    Abstract [en]

    We report observations of electromagnetic electron holes (EHs). We use multispacecraft analysis to quantify the magnetic field contributions of three mechanisms: the Lorentz transform, electron drift within the EH, and Cherenkov emission of whistler waves. The first two mechanisms account for the observed magnetic fields for slower EHs, while for EHs with speeds approaching half the electron Alfven speed, whistler waves excited via the Cherenkov mechanism dominate the perpendicular magnetic field. The excited whistler waves are kinetically damped and typically confined within the EHs.

  • 50.
    Steinvall, Konrad
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lindqvist, P. -A
    KTH Royal Inst Technol, Dept Space & Plasma Phys, Stockholm, Sweden.
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA.
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA.
    Multispacecraft Analysis of Electron Holes2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 1, p. 55-63Article in journal (Refereed)
    Abstract [en]

    Electron holes (EHs) are nonlinear electrostatic structures in plasmas. Most previous in situ studies of EHs have been limited to single‐ and two‐spacecraft methods. We present statistics of EHs observed by Magnetospheric Multiscale on the magnetospheric side of the magnetopause during October 2016 when the spacecraft separation was around 6 km. Each EH is observed by all four spacecraft, allowing EH properties to be determined with unprecedented accuracy. We find that the parallel length scale, l, scales with the Debye length. The EHs can be separated into three groups of speed and potential based on their coupling to ions. We present a method for calculating the perpendicular length scale, l. The method can be applied to a small subset of the observed EHs for which we find shapes ranging from almost spherical to more oblate. For the remaining EHs we use statistical arguments to find l/l≈5, implying dominance of oblate EHs.

    Plain Language Summary: Electron holes are positively charged structures moving along the magnetic field and are frequently observed in space plasmas in relation to strong currents and electron beams. Electron holes interact with the plasma, leading to electron heating and scattering. In order to understand the effect of these electron holes, we need to accurately determine their properties, such as velocity, length scale, and potential. Most earlier studies have relied on single‐ or two‐spacecraft methods to analyze electron holes. In this study we use the four satellites of the Magnetospheric Multiscale mission to analyze 236 electron holes with unprecedented accuracy. We find that the holes can be divided into three distinct groups with different properties. Additionally, we calculate the width of individual electron holes, finding that they are typically much wider than long, resembling

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