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arXiv · 2210.04113

Multi-species Ion Acceleration in 3D Magnetic Reconnection with Hybrid-kinetic Simulations

Qile Zhang·Fan Guo·William Daughton·Hui Li·Ari Le·Tai Phan·Mihir Desai
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Abstract

Magnetic reconnection drives multi-species particle acceleration broadly in space and astrophysics. We perform the first 3D hybrid simulations (fluid electrons, kinetic ions) that contain sufficient scale separation to produce nonthermal heavy-ion acceleration, with fragmented flux ropes critical for accelerating all species. We demonstrate the acceleration of all ion species (up to Fe) into power-law spectra with similar indices, by a common Fermi acceleration mechanism. The upstream ion velocities influence the first Fermi reflection for injection. The subsequent onsets of Fermi acceleration are delayed for ions with lower charge-mass ratios (Q/M), until growing flux ropes magnetize them. This leads to a species-dependent maximum energy/nucleon $\propto(Q/M)^\alpha$. These findings are consistent with in-situ observations in reconnection regions, suggesting Fermi acceleration as the dominant multi-species ion acceleration mechanism.

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Qile Zhang, Fan Guo, William Daughton, Hui Li, Ari Le, Tai Phan, Mihir Desai. 2022-10-08. Multi-species Ion Acceleration in 3D Magnetic Reconnection with Hybrid-kinetic Simulations. https://arxiv.org/abs/2210.04113

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