Particle dynamics in a non-flaring solar active region model
Autor: | Threlfall, J., Bourdin, Ph. -A., Neukirch, T., Parnell, C. E. |
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Rok vydání: | 2015 |
Předmět: | |
Zdroj: | A&A 587, A4 (2016) |
Druh dokumentu: | Working Paper |
DOI: | 10.1051/0004-6361/201526657 |
Popis: | The aim of this work is to investigate and characterise particle behaviour in an (observationally-driven) 3D MHD model of the solar atmosphere above a slowly evolving, non-flaring active region. We use a relativistic guiding-centre particle code to investigate the behaviour of selected particle orbits, distributed throughout a single snapshot of the 3D MHD simulation. Two distinct particle acceleration behaviours are recovered, which affect both electrons and protons: (i) direct acceleration along field lines and (ii) tangential drifting of guiding centres with respect to local magnetic field. However, up to 40\% of all particles actually experience a form of (high energy) particle trap, because of changes in the direction of the electric field and unrelated to the strength of the magnetic field; such particles are included in the first category. Additionally, category (i) electron and proton orbits undergo surprisingly strong acceleration to non-thermal energies ($\lesssim42$MeV), because of the strength and extent of super-Dreicer electric fields created by the MHD simulation. Reducing the electric field strength of the MHD model does not significantly affect the efficiency of the (electric field-based) trapping mechanism, but does reduce the peak energies gained by orbits. We discuss the implications for future experiments, which aim to simulate non-flaring active region heating and reconnection. Comment: submitted to A&A. 14 pages, 8 figures |
Databáze: | arXiv |
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