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Spatiotemporal analysis of the runaway distribution function from synchrotron images in an ASDEX Upgrade disruption

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    0543173 - ÚFP 2022 RIV US eng J - Journal Article
    Hoppe, M. - Hesslow, L. - Embreus, O. - Unnerfelt, L. - Papp, G. - Pusztai, I. - Fülöp, T. - Lexell, O. - Lunt, T. - Macúšová, Eva - McCarthy, P.J. - Pautasso, G. - Pokol, G.I. - Por, G. - Svensson, P.
    Spatiotemporal analysis of the runaway distribution function from synchrotron images in an ASDEX Upgrade disruption.
    Journal of Plasma Physics. Roč. 87, č. 1 (2020), č. článku 855870102. ISSN 0022-3778. E-ISSN 1469-7807
    EU Projects: European Commission(XE) 633053 - EUROfusion
    Institutional support: RVO:61389021
    Keywords : fusion plasma * runaway electrons
    OECD category: Fluids and plasma physics (including surface physics)
    Impact factor: 2.014, year: 2020
    Method of publishing: Open access
    https://www.cambridge.org/core/services/aop-cambridge-core/content/view/D6EB3D8C8555EE96017FAA5A10705254/S002237782000152Xa.pdf

    Synchrotron radiation images from runaway electrons (REs) in an ASDEX Upgrade discharge disrupted by argon injection are analysed using the synchrotron diagnostic tool Soft and coupled fluid-kinetic simulations. We show that the evolution of the runaway distribution is well described by an initial hot-tail seed population, which is accelerated to energies between 25-50 MeV during the current quench, together with an avalanche runaway tail which has an exponentially decreasing energy spectrum. We find that, although the avalanche component carries the vast majority of the current, it is the high-energy seed remnant that dominates synchrotron emission. With insights from the fluid-kinetic simulations, an analytic model for the evolution of the runaway seed component is developed and used to reconstruct the radial density profile of the RE beam. The analysis shows that the observed change of the synchrotron pattern from circular to crescent shape is caused by a rapid redistribution of the radial profile of the runaway density.
    Permanent Link: http://hdl.handle.net/11104/0320446

     
     
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