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arXiv 2307.04769astro-ph.SRphysics.plasm-ph
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太阳耀斑中的波激发与高能电子散射

Wave generation and energetic electron scattering in solar flares

Hanqing Ma, James F. Drake, Marc Swisdak

AI总结:

本文通过二维粒子模拟研究太阳耀斑中电子热流被自生斜向电磁波散射的机制,发现漂移速度与电子Alfvén速度之比是控制散射率的关键参数,并推导出相应标度律。

摘要:

我们进行了二维粒子模拟(particle-in-cell simulations),以研究电子热流被自生斜向电磁波散射的过程。热流被建模为双kappa分布,具有T_parallel > T_perp的温度各向异性,并通过在边界处持续注入来维持。这种各向异性分布激发了斜向哨声波和丝状类Weibel不稳定性。系统达到稳态后获取的电子速度分布表明,这些不稳定性抑制了热流,并驱动总体分布趋于各向同性。速度空间中的电子轨迹显示出沿波参考系中恒定能量表面的类圆形扩散。控制散射率的关键参数是热流的平均速度,即漂移速度vd,与电子Alfvén速度vAe的比值,漂移速度越高,产生的涨落越强,热流的降低也越显著。将携带热流的电子密度降低50%并不会显著影响散射率。从模拟中推导出了电子散射率随vd/vAe变化的标度律。本文讨论了这些结果对理解太阳耀斑能量释放期间高能电子输运的意义。

英文摘要:

We conduct two-dimensional particle-in-cell simulations to investigate the scattering of electron heat flux by self-generated oblique electromagnetic waves. The heat flux is modeled as a bi-kappa distribution with a T_parallel > T_perp temperature anisotropy maintained by continuous injection at the boundaries. The anisotropic distribution excites oblique whistler waves and filamentary-like Weibel instabilities. Electron velocity distributions taken after the system has reached a steady state show that these in stabilities inhibit the heat flux and drive the total distributions towards isotropy. Electron trajectories in velocity space show a circular-like diffusion along constant energy surfaces in the wave frame. The key parameter controlling the scattering rate is the average speed, or drift speed vd, of the heat flux compared with the electron Alfven speed vAe, with higher drift speeds producing stronger fluctua tions and a more significant reduction of the heat flux. Reducing the density of the electrons carrying the heat flux by 50% does not significantly affect the scattering rate. A scaling law for the electron scattering rate versus vd/vAe is deduced from the simulations. The implications of these results for understanding energetic electron transport during solar flare energy release are discussed.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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