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arXiv 2301.00872physics.plasm-phastro-ph.HE
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电子前震II的预加速:斜哨声波

Pre-acceleration in the Electron Foreshock II: Oblique Whistler Waves

Paul J. Morris, Artem Bohdan, Martin S. Weidl, Michelle Tsirou, Karol Fulat, Martin Pohl

摘要:

热电子的回旋半径比冲击波的有限宽度小很多个数量级,因此在它们能够穿过冲击波之前需要被预加速,并通过扩散冲击波加速来加速。可能发生预加速的一个区域是内部前震,上游电子必须在任何潜在的下游交叉之前通过。在本文中,我们进行了一个大规模的粒子模拟,产生一个单一的冲击与参数的动机从超新星遗迹。在前震内,反射的电子激发斜哨声不稳定性,并产生电磁哨声波,它与上游流共同移动,并作为非线性结构,最终达到半径高达5离子回旋半径。我们发现,内部的电磁配置的哨声演变成复杂的非线性结构的强磁场的上游值的4倍左右的约束。虽然这些非线性结构一般不与同空间的上游电子相互作用,但它们与在冲击中反射的电子共振。我们表明,它们可以散射,甚至陷阱,反射电子,限制周围的总上游电子人口的$0.8\%$的区域接近冲击,在那里他们可以进行大量的预加速。这种加速过程类似于随机冲击漂移加速,但效率大约是随机冲击漂移加速的3倍。

英文摘要:

Thermal electrons have gyroradii many orders of magnitude smaller than the finite width of a shock, thus need to be pre-accelerated before they can cross it and be accelerated by diffusive shock acceleration. One region where pre-acceleration may occur is the inner foreshock, which upstream electrons must pass through before any potential downstream crossing. In this paper, we perform a large scale particle-in-cell simulation that generates a single shock with parameters motivated from supernova remnants. Within the foreshock, reflected electrons excite the oblique whistler instability and produce electromagnetic whistler waves, which co-move with the upstream flow and as non-linear structures eventually reach radii of up to 5 ion-gyroradii. We show that the inner electromagnetic configuration of the whistlers evolves into complex non-linear structures bound by a strong magnetic field around 4 times the upstream value. Although these non-linear structures do not in general interact with co-spatial upstream electrons, they resonate with electrons that have been reflected at the shock. We show that they can scatter, or even trap, reflected electrons, confining around $0.8\%$ of the total upstream electron population to the region close to the shock where they can undergo substantial pre-acceleration. This acceleration process is similar to, yet approximately 3 times more efficient than, stochastic shock drift acceleration.

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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