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  • 1.
    Cecconello, Marco
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sperduti, Andrea
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Study of the effect of sawteeth on fast ions and neutron emission in MAST using a neutron camera2018In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 60, no 5, article id 055008Article in journal (Refereed)
    Abstract [en]

    The effect of the sawtooth instability on the confinement of fast ions on MAST, and the impact it has on the neutron emission, has been studied in detail using the TRANSP/NUBEAM codes coupled to a full orbit following code. The sawtooth models in TRANSP/NUBEAM indicate that, on MAST, passing and trapped fast ions are redistributed in approximately equal number and on a level that is consistent with the observations. It has not been possible to discriminate between the different sawtooth models since their predictions are all compatible with the neutron camera observations. Full orbit calculations of the fast ion motion have been used to estimate the characteristic time scales and energy thresholds that according to theoretical predictions govern the fast ions redistribution: no energy threshold for the redistribution for either passing and trapped fast ions was found. The characteristic times have, however, frequencies that are comparable with the frequencies of a m = 1, n = 1 perturbation and its harmonics with toroidal mode numbers n = 2, ..., 4, suggesting that on spherical tokamaks, in addition to the classical sawtooth-induced transport mechanisms of fast ions by attachment to the evolving perturbation and the associated E x B drift, a resonance mechanism between the m = 1 perturbation and the fast ions orbits might be at play.

  • 2.
    Cecconello, Marco
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. EURATOM VR Assoc, Uppsala, Sweden.
    Sperduti, Andrea
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. EURATOM VR Assoc, Uppsala, Sweden.
    Fitzgerald, I.
    Culham Sci Ctr, EURATOM CCFE Fus Assoc, Abingdon, Oxon, England.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. EURATOM VR Assoc, Uppsala, Sweden.
    Holm, Stefan Jarl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. EURATOM VR Assoc, Uppsala, Sweden.
    Weiszflog, Matthias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics. EURATOM VR Assoc, Uppsala, Sweden.
    The neutron camera upgrade for MAST Upgrade2018In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 89, no 10, article id 10I110Article in journal (Refereed)
    Abstract [en]

    The Neutron Camera Upgrade (NCU) is a neutron flux monitor consisting of six lines of sight (LoSs) under installation on Mega Ampere Spherical Tokamak (MAST) Upgrade. The NCU is expected to contribute to the study of the confinement of fast ions and on the efficiency of non-inductive current drive in the presence of on-axis and off-axis neutral beam injection by measuring the neutron emissivity profile along the equatorial plane. This paper discusses the NCU main design criteria, the engineering and interfacing issues, and the solutions adopted. In addition, the results from the characterization and performance studies of the neutron detectors using standard gamma-rays sources and a Cf-252 source are discussed. The proposed design has a time resolution of 1 ms with a statistical uncertainty of less than 10% for all MAST Upgrade scenarios with a spatial resolution of 10 cm: higher spatial resolution is possible by moving the LoSs in-between plasma discharges. The energy resolution of the neutron detector is better than 10% for a light output of 0.8 MeVee, and the measured pulse shape discrimination is satisfactory.

  • 3.
    Harrison, J. R.
    et al.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Akers, R. J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Allan, S. Y.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Allcock, J. S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Durham, Ctr Adv Instrumentat, South Rd, Durham DH1 3LE, England.
    Allen, J. O.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Appel, L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Barnes, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Plasma Sci & Fus Ctr, 167 Albany St, Cambridge, MA 02139 USA.
    Ben Ayedl, N.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Boeglin, W.
    Florida Int Univ, Dept Phys, 11200 SW, Miami, FL 33199 USA.
    Bowman, C.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Bradley, J.
    Univ Liverpool, Dept Elect Engn & Elect, Brownlow Hill, Liverpool L69 3GJ, Merseyside, England.
    Browning, P.
    Univ Manchester, Sch Phys & Astron, Oxford Rd, Manchester M13 9PL, Lancs, England.
    Bryant, P.
    Univ Liverpool, Dept Elect Engn & Elect, Brownlow Hill, Liverpool L69 3GJ, Merseyside, England.
    Carr, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Challis, C. D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Chapman, S.
    Univ Warwick, Ctr Fus Space & Astrophys, Dept Phys, Coventry CV4 7AL, W Midlands, England.
    Chapman, I. T.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Colyer, G. J.
    Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Univ Exeter, Engn Math & Phys Sci, Exeter EX4 4QF, Devon, England.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conway, N. J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Cox, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Cunningham, G.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Dendy, R. O.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Warwick, Ctr Fus Space & Astrophys, Dept Phys, Coventry CV4 7AL, W Midlands, England.
    Dorland, W.
    Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Univ Maryland, Dept Phys, College Pk, MD 20742 USA.
    Dudson, B. D.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Easy, L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Elmore, S. D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Farley, T.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Liverpool, Dept Elect Engn & Elect, Brownlow Hill, Liverpool L69 3GJ, Merseyside, England.
    Feng, X.
    Univ Durham, Ctr Adv Instrumentat, South Rd, Durham DH1 3LE, England.
    Field, A. R.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Fil, A.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Fishpool, G. M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Fitzgerald, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Flesch, K.
    Univ Wisconsin, Madison, WI USA.
    Fox, M. F. J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Univ Oxford Merton Coll, Oxford OX1 4JD, England.
    Frerichs, H.
    Univ Wisconsin, Madison, WI USA.
    Gadgil, S.
    Univ Warwick, Ctr Fus Space & Astrophys, Dept Phys, Coventry CV4 7AL, W Midlands, England.
    Gahle, D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Strathclyde, Dept Phys SUPA, Glasgow G4 ONG, Lanark, Scotland.
    Garzotti, L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Ghim, Y-C
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Korea Adv Inst Sci & Technol, Dept Nucl & Quantum Engn, Daejeon 34141, South Korea.
    Gibson, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Durham, Ctr Adv Instrumentat, South Rd, Durham DH1 3LE, England.
    Gibson, K. J.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Hall, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Ham, C.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Heiberg, N.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Henderson, S. S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Highcock, E.
    Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden.
    Hnat, B.
    Univ Warwick, Ctr Fus Space & Astrophys, Dept Phys, Coventry CV4 7AL, W Midlands, England.
    Howard, J.
    Australian Natl Univ, Plasma Res Lab, Canberra, ACT 0200, Australia.
    Huang, J.
    Chinese Acad Sci, Inst Plasma Phys, PO 1126, Hefei 230031, Anhui, Peoples R China.
    Irvine, S. W. A.
    Univ Warwick, Ctr Fus Space & Astrophys, Dept Phys, Coventry CV4 7AL, W Midlands, England.
    Jacobsen, A. S.
    Max Planck Inst Plasma Phys, Garching, Germany.
    Jones, O.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Durham, Ctr Adv Instrumentat, South Rd, Durham DH1 3LE, England.
    Katramados, I
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Keeling, D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Kirk, A.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Klimek, Iwona
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Kogan, L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Leland, J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Liverpool, Dept Elect Engn & Elect, Brownlow Hill, Liverpool L69 3GJ, Merseyside, England.
    Lipschultz, B.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Lloyd, B.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Lovell, J.
    Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA.
    Madsen, B.
    Tech Univ Denmark, Dept Phys, Lyngby, Denmark.
    Marshall, O.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Martin, R.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    McArdle, G.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    McClements, K.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    McMillan, B.
    Univ Warwick, Ctr Fus Space & Astrophys, Dept Phys, Coventry CV4 7AL, W Midlands, England.
    Meakins, A.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Meyer, H. F.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Militello, F.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Milnes, J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Mordijck, S.
    Coll William & Mary, Dept Comp Sci, Williamsburg, VA 23185 USA.
    Morris, A. W.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Moulton, D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Muir, D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Mukhi, K.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Manchester, Sch Phys & Astron, Oxford Rd, Manchester M13 9PL, Lancs, England.
    Murphy-Sugrue, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Liverpool, Dept Elect Engn & Elect, Brownlow Hill, Liverpool L69 3GJ, Merseyside, England.
    Myatra, O.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Naylor, G.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Naylor, P.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Newton, S. L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    O'Gorman, T.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Omotani, J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    O'Mullane, M. G.
    Univ Strathclyde, Dept Phys SUPA, Glasgow G4 ONG, Lanark, Scotland.
    Orchard, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Pamela, S. J. P.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Pangione, L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Parra, F.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England.
    Perez, R. , V
    Piron, L.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Price, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Reinke, M. L.
    Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA.
    Riva, F.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Roach, C. M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Robb, D.
    Univ Glasgow, Dept Phys & Astron, Glasgow G12 8QQ, Lanark, Scotland.
    Ryan, D.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Saarelma, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Salewski, M.
    Tech Univ Denmark, Dept Phys, Lyngby, Denmark.
    Scannell, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Schekochihin, A. A.
    Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;Univ Oxford Merton Coll, Oxford OX1 4JD, England.
    Schmitz, O.
    Univ Wisconsin, Madison, WI USA.
    Sharapov, S.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Sharples, R.
    Univ Durham, Ctr Adv Instrumentat, South Rd, Durham DH1 3LE, England.
    Silburn, S. A.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Smith, S. F.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Sperduti, Andrea
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Stephen, R.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Thomas-Davies, N. T.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Thornton, A. J.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Turnyanskiy, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Valovic, M.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Van Wyk, F.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3PU, England;STFC Daresbury Lab, Daresbury WA4 4AD, Cheshire, England.
    Vann, R. G. L.
    Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Walkden, N. R.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England.
    Waters, I
    Univ Wisconsin, Madison, WI USA.
    Wilson, H. R.
    CCFE, Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England;Univ York, York Plasma Inst, Dept Phys, York YO10 5DD, N Yorkshire, England.
    Overview of new MAST physics in anticipation of first results from MAST Upgrade2019In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 11, article id 112011Article in journal (Refereed)
    Abstract [en]

    The mega amp spherical tokamak (MAST) was a low aspect ratio device (R/a = 0.85/0.65 similar to 1.3) with similar poloidal cross-section to other medium-size tokamaks. The physics programme concentrates on addressing key physics issues for the operation of ITER, design of DEMO and future spherical tokamaks by utilising high resolution diagnostic measurements closely coupled with theory and modelling to significantly advance our understanding. An empirical scaling of the energy confinement time that favours higher power, lower collisionality devices is consistent with gyrokinetic modelling of electron scale turbulence. Measurements of ion scale turbulence with beam emission spectroscopy and gyrokinetic modelling in up-down symmetric plasmas find that the symmetry of the turbulence is broken by flow shear. Near the non-linear stability threshold, flow shear tilts the density fluctuation correlation function and skews the fluctuation amplitude distribution. Results from fast particle physics studies include the observation that sawteeth are found to redistribute passing and trapped fast particles injected from neutral beam injectors in equal measure, suggesting that resonances between the m = 1 perturbation and the fast ion orbits may be playing a dominant role in the fast ion transport. Measured D-D fusion products from a neutron camera and a charged fusion product detector are 40% lower than predictions from TRANSP/NUBEAM, highlighting possible deficiencies in the guiding centre approximation. Modelling of fast ion losses in the presence of resonant magnetic perturbations (RMPs) can reproduce trends observed in experiments when the plasma response and charge-exchange losses are accounted for. Measurements with a neutral particle analyser during merging-compression start-up indicate the acceleration of ions and electrons. Transport at the plasma edge has been improved through reciprocating probe measurements that have characterised a geodesic acoustic mode at the edge of an ohmic L-mode plasma and particle-in-cell modelling has improved the interpretation of plasma potential estimates from ball-pen probes. The application of RMPs leads to a reduction in particle confinement in L-mode and H-mode and an increase in the core ionization source. The ejection of secondary filaments following type-I ELMs correlates with interactions with surfaces near the X-point. Simulations of the interaction between pairs of filaments in the scrape-off layer suggest this results in modest changes to their velocity, and in most cases can be treated as moving independently. A stochastic model of scrape-off layer profile formation based on the superposition of non-interacting filaments is in good agreement with measured time-average profiles. Transport in the divertor has been improved through fast camera imaging, indicating the presence of a quiescent region devoid of filament near the X-point, extending from the separatrix to psi(n) similar to 1.02. Simulations of turbulent transport in the divertor show that the angle between the divertor leg on the curvature vector strongly influences transport into the private flux region via the interchange mechanism. Coherence imaging measurements show counter-streaming flows of impurities due to gas puffing increasing the pressure on field lines where the gas is ionised. MAST Upgrade is based on the original MAST device, with substantially improved capabilities to operate with a Super-X divertor to test extended divertor leg concepts. SOLPS-ITER modelling predicts the detachment threshold will be reduced by more than a factor of 2, in terms of upstream density, in the Super-X compared with a conventional configuration and that the radiation front movement is passively stabilised before it reaches the X-point. 1D fluid modelling reveals the key role of momentum and power loss mechanisms in governing detachment onset and evolution. Analytic modelling indicates that long legs placed at large major radius, or equivalently low B at the target compared with the X-point arc more amenable to external control. With MAST Upgrade experiments expected in 2019, a thorough characterisation of the sources of the intrinsic error field has been carried out and a mitigation strategy developed.

  • 4. Labit, B.
    et al.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Sperduti, Andrea
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Zuin, M.
    Dependence on plasma shape and plasma fueling for small edge-localized mode regimes in TCV and ASDEX Upgrade2019In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 8, article id 086020Article in journal (Refereed)
    Abstract [en]

    Within the EUROfusion MST1 work package, a series of experiments has been conducted on AUG and TCV devices to disentangle the role of plasma fueling and plasma shape for the onset of small ELM regimes. On both devices, small ELM regimes with high confinement are achieved if and only if two conditions are fulfilled at the same time. Firstly, the plasma density at the separatrix must be large enough (n(e,sep)/n(G) similar to 0.3), leading to a pressure profile flattening at the separatrix, which stabilizes type-I ELMs. Secondly, the magnetic configuration has to be close to a double null (DN), leading to a reduction of the magnetic shear in the extreme vicinity of the separatrix. As a consequence, its stabilizing effect on ballooning modes is weakened.

  • 5.
    Sperduti, Andrea
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Angelone, M.
    ENEA, Dept Fus & Technol Nucl Safety & Secur, Via E Fermi 45, I-00044 Frascati, Italy..
    Bedogni, R.
    Ist Nazl Fis Nucl, Frascati Natl Labs, Via E Fermi 44, I-00044 Frascati, Italy..
    Claps, G.
    ENEA, Dept Fus & Technol Nucl Safety & Secur, Via E Fermi 45, I-00044 Frascati, Italy..
    Diociaiuti, E.
    Ist Nazl Fis Nucl, Frascati Natl Labs, Via E Fermi 44, I-00044 Frascati, Italy..
    Domingo, C.
    Univ Autonoma Barcelona, Phys Dept, Pl Civ S-N, E-08193 Barcelona, Spain..
    Donghia, R.
    Ist Nazl Fis Nucl, Frascati Natl Labs, Via E Fermi 44, I-00044 Frascati, Italy..
    Giovannella, S.
    Ist Nazl Fis Nucl, Frascati Natl Labs, Via E Fermi 44, I-00044 Frascati, Italy..
    Gomez-Ros, J. M.
    CIEMAT, Av Complutense 40, E-28040 Madrid, Spain..
    Irazola-Rosales, L.
    Univ Seville, Dept Fisiol Med & Biofis, Calle Dr Fedriani 3, E-41009 Seville, Spain..
    Loreti, S.
    ENEA, Dept Fus & Technol Nucl Safety & Secur, Via E Fermi 45, I-00044 Frascati, Italy..
    Monti, V.
    Ist Nazl Fis Nucl, Sez Torino, Via Pietro Giuria 1, I-10125 Turin, Italy..
    Miscetti, S.
    Ist Nazl Fis Nucl, Frascati Natl Labs, Via E Fermi 44, I-00044 Frascati, Italy..
    Murtas, F.
    Ist Nazl Fis Nucl, Frascati Natl Labs, Via E Fermi 44, I-00044 Frascati, Italy..
    Pagano, G.
    ENEA, Dept Fus & Technol Nucl Safety & Secur, Via E Fermi 45, I-00044 Frascati, Italy..
    Pillon, M.
    ENEA, Dept Fus & Technol Nucl Safety & Secur, Via E Fermi 45, I-00044 Frascati, Italy..
    Pilotti, R.
    ENEA, Dept Fus & Technol Nucl Safety & Secur, Via E Fermi 45, I-00044 Frascati, Italy..
    Pola, A.
    Politecn Milan, Energy Dept, Via La Masa 34, I-20156 Milan, Italy..
    Romero-Exposito, M.
    Univ Autonoma Barcelona, Phys Dept, Pl Civ S-N, E-08193 Barcelona, Spain..
    Sanchez-Doblado, F.
    CIEMAT, Av Complutense 40, E-28040 Madrid, Spain..
    Sans-Planell, O.
    Univ Rovira & Virgili, Carrer Escorxador S-N, Tarragona 43003, Spain..
    Scherillo, A.
    ISIS Facil, Sci & Technol Facil Council, Didcot 0Q11, Oxon, England..
    Soldani, E.
    Ist Nazl Fis Nucl, Frascati Natl Labs, Via E Fermi 44, I-00044 Frascati, Italy..
    Treccani, M.
    Univ Autonoma Barcelona, Phys Dept, Pl Civ S-N, E-08193 Barcelona, Spain..
    Pietropaolo, A.
    Ist Nazl Fis Nucl, Frascati Natl Labs, Via E Fermi 44, I-00044 Frascati, Italy..
    Results of the first user program on the HOmogeneous Thermal NEutron Source HOTNES (ENEA/INFN)2017In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 12, article id P12029Article in journal (Refereed)
    Abstract [en]

    The HOmogeneous Thermal NEutron Source (HOTNES) is a new type of thermal neutron irradiation assembly developed by the ENEA-INFN collaboration. The facility is fully characterized in terms of neutron field and dosimetric quantities, by either computational and experimental methods. This paper reports the results of the first "HOTNES users program", carried out in 2016, and covering a variety of thermal neutron active detectors such as scintillators, solid-state, single crystal diamond and gaseous detectors.

  • 6.
    Sperduti, Andrea
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    On the limits of the Influence Method in the determination of the intrinsic efficiency of liquid scintillators2019In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 14, article id P06004Article in journal (Refereed)
    Abstract [en]

    The limitations of the Influence Method for the determination of the intrinsic efficiency of a EJ-301 liquid scintillator to gamma-rays and neutrons in the MeV range is presented. Discrepancies between the intrinsic efficiencies, measured according to the Influence Method, and their accepted values are reported and investigated using MCNP6. It was found that this discrepancy is caused by multiple scattering of both gamma-rays and neutrons in the detector, effects which are not properly accounted for in the Influence Method. Correction factors have been calculated in MCNP6 for different detector geometries and different gamma-ray and neutron energies. A simple correction factor is derived, which can be used to calculate the correct intrinsic efficiency for similar detectors using the Influence Method without having to recur to Monte Carlo simulation.

  • 7.
    Sperduti, Andrea
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Cecconello, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Conroy, Sean
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Jacobsen, A. S.
    Culham Sci Ctr, Culham Ctr Fus Energy, Abingdon OX14 3DB, Oxon, England.
    Velocity-space sensitivity of the neutron camera on MAST2019In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 14, article id C09005Article in journal (Refereed)
    Abstract [en]

    The Neutron Camera installed at the Mega Ampere Spherical Tokamak (MAST) provided fundamental information regarding the neutron emission and the behavior of fast ions. The signal measured by the Neutron Camera depended on its observation direction relative to the plasma region. Furthermore, only a certain part of the energy-pitch region contributed to the measured signal. This region is determined by the fast ion Weight Functions. In this paper, the Weight Functions of the Neutron Camera are calculated using DRESS. The results show that the instrument is most sensitive to neutrons created in fusion reactions involving a thermal ion and an ion in the beam energy region. Synthetic spectra are also calculated and, after folding with the detector's response function, compared with experimental pulse height spectra for three selected plasma discharges. Also, Weight Functions for the Neutron Camera Upgrade on MAST-U are calculated and discussed. The results can be applied for future fast ion studies at MAST-U, combining Neutron Camera Upgrade data with those of other fast ion diagnostics, such as Fast Ion Deuterium Alpha and the Neutral Particle Analyzer diagnostics.

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