uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Statistics and accuracy of magnetic null identification in multispacecraft data
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.
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, Swedish Institute of Space Physics, Uppsala Division.
Taras Shevchenko Natl Univ Kyiv, Dept Theoret Phys, Kiev, Ukraine..
Show others and affiliations
2015 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, 6883-6889 p.Article in journal (Refereed) Published
Abstract [en]

Complex magnetic topologies are ubiquitous in astrophysical plasmas. Analyzing magnetic nulls, regions of vanishing magnetic field, is one way to characterize 3-D magnetic topologies. Magnetic nulls are believed to be important in 3-D reconnection and turbulence. In the vicinity of a null, plasma particles become unmagnetized and can be accelerated to high energies by electric fields. We present the first statistical study of the occurrence of magnetic nulls and their types in the Earth's nightside magnetosphere. We are able to identify the nulls both in the tail and in the magnetopause current sheets. On average, we find one null for every few current sheet crossings. We show that the type identification of magnetic nulls may be sensitive to local fluctuations in the magnetic field. We develop and demonstrate a method to estimate the reliability of the magnetic null type identification.

Place, publisher, year, edition, pages
2015. Vol. 42, 6883-6889 p.
National Category
Geophysics Fusion, Plasma and Space Physics
Identifiers
URN: urn:nbn:se:uu:diva-267334DOI: 10.1002/2015GL064959ISI: 000363411200002OAI: oai:DiVA.org:uu-267334DiVA: diva2:873635
Funder
Swedish Research Council, 2013-4309
Available from: 2015-11-24 Created: 2015-11-20 Last updated: 2017-12-01Bibliographically approved
In thesis
1. 3D Magnetic Nulls and Regions of Strong Current in the Earth's Magnetosphere
Open this publication in new window or tab >>3D Magnetic Nulls and Regions of Strong Current in the Earth's Magnetosphere
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Plasma, a gas of charged particles exhibiting collective behaviour, can be found everywhere in our vast Universe. The characteristics of plasma in very distant parts of the Universe can be similar to characteristics in our solar system and near-Earth space. We can therefore gain an understanding of what happens in astrophysical plasmas by studying processes occurring in near Earth space, an environment much easier to reach.

Large volumes in space are filled with plasma and when different plasmas interact distinct boundaries are often created. Many important physical processes, for example particle acceleration, occur at these boundaries. Thus, it is very important to study and understand such boundaries. In Paper I we study magnetic nulls, regions of vanishing magnetic fields, that form inside boundaries separating plasmas with different magnetic field orientations. For the first time, a statistical study of magnetic nulls in the Earth’s nightside magnetosphere has been done by using simultaneous measurements from all four Cluster spacecraft. We find that magnetic nulls occur both in the magnetopause and the magnetotail. In addition, we introduce a method to determine the reliability of the type identification of the observed nulls. In the manuscript of Paper II we study a different boundary, the shocked solar wind plasma in the magnetosheath, using the new Magnetospheric Multiscale mission. We show that a region of strong current in the form of a current sheet is forming inside the turbulent magnetosheath behind a quasi-parallel shock. The strong current sheet can be related to the jets with extreme dynamic pressure, several times that of the undisturbed solar wind dynamic pressure. The current sheet is also associated with electron acceleration parallel to the background magnetic field. In addition, the current sheet satisfies the Walén relation suggesting that plasmas on both sides of the current region are magnetically connected. We speculate on the formation mechanisms of the current sheet and the physical processes inside and around the current sheet.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. 32 p.
Keyword
Magnetic Nulls, Particle Acceleration, Current sheets, Magnetic reconnection, Magnetosphere
National Category
Fusion, Plasma and Space Physics
Research subject
Physics with specialization in Space and Plasma Physics
Identifiers
urn:nbn:se:uu:diva-292742 (URN)
Presentation
2016-05-27, Polhelmsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council, 2013-4309
Available from: 2016-05-16 Created: 2016-05-09 Last updated: 2016-05-16Bibliographically approved

Open Access in DiVA

fulltext(1585 kB)59 downloads
File information
File name FULLTEXT01.pdfFile size 1585 kBChecksum SHA-512
31970f175f4239b075466658ca201b71154715a00536fa2b0c66256ae69ab2afa06b63e507e5689a067d03bda163151ab6c6075c6e513a782db987a4c8bd7a1e
Type fulltextMimetype application/pdf

Other links

Publisher's full text

Authority records BETA

Eriksson, ElinVaivads, AndrisKhotyaintsev, Yuri. V.Andre, Mats

Search in DiVA

By author/editor
Eriksson, ElinVaivads, AndrisKhotyaintsev, Yuri. V.Andre, Mats
By organisation
Department of Physics and AstronomySwedish Institute of Space Physics, Uppsala Division
In the same journal
Geophysical Research Letters
GeophysicsFusion, Plasma and Space Physics

Search outside of DiVA

GoogleGoogle Scholar
Total: 59 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 354 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf