Lyutikov, M, Sironi, L, Komissarov, SS et al. (1 more author) (2017) Particle acceleration in relativistic magnetic flux-merging events. Journal of Plasma Physics, 83 (6). 635830602. ISSN 0022-3778
Abstract
Using analytical and numerical methods (fluid and particle-in-cell simulations) we study a number of model problems involving merger of magnetic flux tubes in relativistic magnetically dominated plasma. Mergers of current-carrying flux tubes (exemplified by the two-dimensional ‘ABC’ structures) and zero-total-current magnetic flux tubes are considered. In all cases regimes of spontaneous and driven evolution are investigated. We identify two stages of particle acceleration during flux mergers: (i) fast explosive prompt X-point collapse and (ii) ensuing island merger. The fastest acceleration occurs during the initial catastrophic X-point collapse, with the reconnection electric field of the order of the magnetic field. During the X-point collapse, particles are accelerated by charge-starved electric fields, which can reach (and even exceed) values of the local magnetic field. The explosive stage of reconnection produces non-thermal power-law tails with slopes that depend on the average magnetization σ. For plasma magnetization σ⩽10² the spectrum power-law index is Ρ>2; in this case the maximal energy depends linearly on the size of the reconnecting islands. For higher magnetization, σ⩾10², the spectra are hard, Ρ<2, yet the maximal energy Υmax can still exceed the average magnetic energy per particle, ~σ, by orders of magnitude (if Ρ is not too close to unity). The X-point collapse stage is followed by magnetic island merger that dissipates a large fraction of the initial magnetic energy in a regime of forced magnetic reconnection, further accelerating the particles, but proceeds at a slower reconnection rate.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | (c) Cambridge University Press 2017. This article has been published in a revised form in Journal of Plasma Physics https://doi.org/10.1017/S002237781700071X. This version is free to view and download for private research and study only. Not for re-distribution, re-sale or use in derivative works. |
Keywords: | magnetized plasmas; plasma nonlinear phenomena; space plasma physics |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mathematics (Leeds) > Applied Mathematics (Leeds) |
Funding Information: | Funder Grant number Science & Technology Facilities Council (STFC) ST/K000853/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 30 May 2018 13:42 |
Last Modified: | 12 Feb 2019 13:57 |
Status: | Published |
Publisher: | Cambridge University Press |
Identification Number: | 10.1017/S002237781700071X |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:131335 |