Ion Beam Instabilities during Solar Flare Energy Release

Fuente: arXiv
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Auteurs principaux: Fitzmaurice, A., Drake, J. F., Swisdak, M.
Format: Preprint
Publié: 2025
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author Fitzmaurice, A.
Drake, J. F.
Swisdak, M.
author_facet Fitzmaurice, A.
Drake, J. F.
Swisdak, M.
contents The linear stability of waves driven by ion beams produced during solar flare energy release are explored to assess their role in driving abundance enhancements in minority species such as $^3$He and in controlling, through pitch-angle scattering, proton/alpha confinement during energy release. The Arbitrary Linear Plasma Solver (ALPS) is used to solve the linear dispersion relation for a population of energetic, reconnection-accelerated protons streaming into a cold background plasma. We assume equal densities of the two populations, using an anisotropic ($T_\parallel/T_\perp = 10$), one-sided kappa distribution for the energetic streaming population and a cold Maxwellian for the background. We find two unstable modes with parallel propagation: a right-handed wave with a frequency of the order of the proton cyclotron frequency ($Ω_{cp}$) and a left-handed, lower frequency mode. We also find highly oblique modes with frequencies below $Ω_{cp}$ that are unstable for higher beam energies. Through resonant interactions, all three modes will contribute to the scattering of the high-energy protons, thereby limiting their transport out of the flare-acceleration region. The higher-frequency oblique mode, which can be characterized as a kinetic Alfvén wave, will preferentially heat $^3$He, making it a good candidate for the driver of the abundance enhancements commonly observed for this species in impulsive events.
format Preprint
id arxiv_https___arxiv_org_abs_2501_14898
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Ion Beam Instabilities during Solar Flare Energy Release
Fitzmaurice, A.
Drake, J. F.
Swisdak, M.
Solar and Stellar Astrophysics
Plasma Physics
Space Physics
The linear stability of waves driven by ion beams produced during solar flare energy release are explored to assess their role in driving abundance enhancements in minority species such as $^3$He and in controlling, through pitch-angle scattering, proton/alpha confinement during energy release. The Arbitrary Linear Plasma Solver (ALPS) is used to solve the linear dispersion relation for a population of energetic, reconnection-accelerated protons streaming into a cold background plasma. We assume equal densities of the two populations, using an anisotropic ($T_\parallel/T_\perp = 10$), one-sided kappa distribution for the energetic streaming population and a cold Maxwellian for the background. We find two unstable modes with parallel propagation: a right-handed wave with a frequency of the order of the proton cyclotron frequency ($Ω_{cp}$) and a left-handed, lower frequency mode. We also find highly oblique modes with frequencies below $Ω_{cp}$ that are unstable for higher beam energies. Through resonant interactions, all three modes will contribute to the scattering of the high-energy protons, thereby limiting their transport out of the flare-acceleration region. The higher-frequency oblique mode, which can be characterized as a kinetic Alfvén wave, will preferentially heat $^3$He, making it a good candidate for the driver of the abundance enhancements commonly observed for this species in impulsive events.
title Ion Beam Instabilities during Solar Flare Energy Release
topic Solar and Stellar Astrophysics
Plasma Physics
Space Physics
url https://arxiv.org/abs/2501.14898