Role of Suprathermal Runaway Electrons Returning to the Acceleration Region in Solar Flares
Role of Suprathermal Runaway Electrons Returning to the Acceleration Region in Solar Flares
复制标题
超热失控电子返回加速区在太阳耀斑中的作用
DOI：
10.3847/1538-4357/ac0820
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
R. Eufrasio
中科院分区：
文献类型：
--
作者：
M. Alaoui;G. Holman;J. Allred;R. Eufrasio
在太阳耀斑期间，大量高能电子从重新连接的磁通量管的顶部向低层大气传播。在电子传输过程中，会产生同空间逆流返回电流，从而平衡电流密度。为了响应返回电流电场，周围电子的一部分将被加速进入失控状态。然而，描述加速电子束/回流系统的模型之前并未自洽地考虑这些超热失控电子。我们开发了一个模型，其中加速电子束驱动稳态、亚德莱瑟共空间返回电流电场，该电场局部平衡直接束电流并自由加速一小部分背景（返回电流）电子。该模型是自洽的，即考虑了直射束和失控电流共同演化引起的电场。我们发现（1）返回电流电场可以将大量超热电子返回到加速区域，在那里它们可以进一步加速到更高的能量，失控电子可以是返回非热束加速区域的返回电流通量的百分之几十，（2）超热电子的能量增益可以高达10-35 keV，（3）对于介质来说，日冕中的加热速率可以降低3倍与忽略失控分量的模型相比，范围注入通量。结果取决于注入的束流密度、温度和背景等离子体的密度。
During solar flares, a large flux of energetic electrons propagate from the tops of reconnecting magnetic flux tubes toward the lower atmosphere. Over the course of the electrons’ transport, a co-spatial counterstreaming return current is induced, thereby balancing the current density. In response to the return-current electric field, a fraction of the ambient electrons will be accelerated into the runaway regime. However, models describing the accelerated electron beam/return-current system have not previously taken these suprathermal runaway electrons into account self-consistently. We develop a model in which an accelerated electron beam drives a steady-state, sub-Dreicer co-spatial return-current electric field, which locally balances the direct beam current and freely accelerates a fraction of background (return-current) electrons. The model is self-consistent, i.e., the electric field induced by the coevolution of the direct beam and the runaway current is considered. We find that (1) the return-current electric field can return a significant number of suprathermal electrons to the acceleration region, where they can be further accelerated to higher energies, runaway electrons can be a few tens of percent of the return-current flux returning to the nonthermal beam’s acceleration region, (2) the energy gain of the suprathermal electrons can be up to 10–35 keV, (3) the heating rate in the corona can be reduced by a factor of 3 for medium range injected fluxes in comparison to models which neglect the runaway component. The results depend on the injected beam flux density, the temperature, and density of the background plasma.
影响因子：
2.5
作者：
T. Siversky;V. Zharkova
通讯作者：
T. Siversky;V. Zharkova
影响因子：
4.9
作者：
Gary, Dale E.;Chen, Bin;Yu, Sijie
通讯作者：
Yu, Sijie