arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1203.4497astro-ph.SRphysics.plasm-ph
收藏

耀斑中高能电子输运的双层抑制

Suppression of energetic electron transport in flares by double layers

T. C. Li, J. F. Drake, M. Swisdak

摘要:

在耀斑和日冕物质抛射期间,来自日冕源的高能电子与穿过系统的渡越时间相比通常具有非常长的寿命,这表明在源区域中的限制。利用粒子模拟方法研究了高能电子输运从日冕到色球层的传输机制和可能的禁闭机制。我们建立了一个初始系统的预加速热电子与周围的冷电子接触沿本地磁场,并让它随着时间的推移而演变。通过非线性的,高度局部化的静电电场(在一个双层的形式)的传输抑制后,观察到一个短的阶段的自由流动的热电子。双电层(DL)出现在两个电子布居的接触处。它是由离子-电子流不稳定性驱动的,这是由于回流返回电流电子与离子相互作用的漂移造成的。DL随着时间的推移而增长,并支持温度的显着下降,因此减少了在模拟期间持续的两个区域之间的热通量。这项研究表明,当高能电子开始从日冕加速点传播出去时,传输抑制就开始了。这也意味着对于DL寿命,具有小于DL的静电能的动能的高能电子的约束,DL寿命比通过源极区的电子渡越时间长得多。

英文摘要:

During flares and coronal mass ejections, energetic electrons from coronal sources typically have very long lifetimes compared to the transit times across the systems, suggesting confinement in the source region. Particle-in-cell simulations are carried out to explore the mechanisms of energetic electron transport from the corona to the chromosphere and possible confinement. We set up an initial system of pre-accelerated hot electrons in contact with ambient cold electrons along the local magnetic field, and let it evolve over time. Suppression of transport by a nonlinear, highly localized electrostatic electric field (in the form of a double layer) is observed after a short phase of free-streaming by hot electrons. The double layer (DL) emerges at the contact of the two electron populations. It is driven by an ion-electron streaming instability due to the drift of the back-streaming return current electrons interacting with the ions. The DL grows over time and supports a significant drop in temperature and hence reduces heat flux between the two regions that is sustained for the duration of the simulation. This study shows transport suppression begins when the energetic electrons start to propagate away from a coronal acceleration site. It also implies confinement of energetic electrons with kinetic energies less than the electrostatic energy of the DL for the DL lifetime, which is much longer than the electron transit time through the source region.

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。

↑