Generation of Electron Suprathermal Tails in the Upper Solar Atmosphere: Implications for Coronal Heating
Generation of Electron Suprathermal Tails in the Upper Solar Atmosphere: Implications for Coronal Heating
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太阳高层大气中电子超热尾的产生：对日冕加热的影响
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
A. Klimas
中科院分区：
文献类型：
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作者：
A. Viñas;H. Wong;A. Klimas
我们提出了一种在存在碰撞阻尼的情况下在太阳大气上部区域产生非麦克斯韦电子分布函数的机制。结果表明，有限幅度、低频、斜向传播的电磁波可以携带一个与平均磁场平行的电场分量，该分量可以明显大于德雷切尔电场。这种长波长电涨落能够产生高频电子等离子体振荡和低频离子声波。分析是用1-1/2D Vlasov和PIC数值模拟进行的，其中电子和离子都是自洽的动力学处理。模拟结果表明，产生了高频电子等离子体振荡和低频类离子声波。高频电子等离子体振荡驱动电子等离子体湍流，随后被背景电子所抑制。湍流衰减导致电子加速和非麦克斯韦超热尾巴的产生，与碰撞衰减相比，时间尺度较短。如果波动的平行电场足够强，也会发生整体加热。这项研究表明，有限幅度、低频、斜传播的电磁波可以在日冕电子的加速和加热以及中小尺度现象的耦合中发挥重要作用。
We present a mechanism for the generation of non-Maxwellian electron distribution function in the upper regions of the solar atmosphere in the presence of collisional damping. It is suggested that finite-amplitude, low-frequency, obliquely propagating electromagnetic waves can carry a substantial electric field component parallel to the mean magnetic field that can be significantly larger than the Dreicer electric field. This long-wavelength electric fluctuation is capable of generating high-frequency electron plasma oscillations and low-frequency ion acoustic-like waves. The analysis has been performed using 1-1/2D Vlasov and PIC numerical simulations in which both electrons and ions are treated kinetically and self consistently. The simulation results indicate that high-frequency electron plasma oscillations and low-frequency ion acoustic-like waves are generated. The high-frequency electron plasma oscillation drives electron plasma turbulence, which subsequently is damped out by the background electrons. The turbulence damping results in electron acceleration and the generation of non-Maxwellian suprathermal tails on timescales short compared to collisional damping. Bulk heating also occurs if the fluctuating parallel electric field is strong enough. This study suggests that finite-amplitude, low-frequency, obliquely propagating electromagnetic waves can play a significant role in the acceleration and heating of the solar corona electrons and in the coupling of medium and small-scale phenomena.