The theory of the acceleration of auroral particles is reviewed, focusing on developments in the last 15 years. We discuss elementary plasma physics processes leading to acceleration of electrons to energies compatible with emission observed for quiet, discrete auroral arcs, defined as arcs that have time scales of minutes or more and spatial scales ranging from less than 1 km to tens of kilometers. For context, earlier observations are first described briefly. The theoretical fundamentals of auroral particle acceleration are based on the kinetic theory of plasmas, in particular the development of parallel electric fields. These parallel electric fields can either be distributed along the magnetic field lines, often associated with the mirror geometry of the geomagnetic field, or concentrated into narrow regions of charge separation known as double layers. Observations have indicated that the acceleration process depends on whether the field-aligned currents are directed away from the Earth, toward the Earth, or in mixed regions of currents often associated with the propagation of Alfvén waves. Recent observations from the NASA Fast Auroral SnapshoT (FAST) satellite, the ESA satellite constellation Cluster, and the Japanese Reimei satellite have provided new insights into the auroral acceleration process and have led to further refinements to the theory of auroral particle acceleration.

中文翻译：

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安静、离散的极光弧：加速机制

回顾了极光粒子加速的理论，重点是过去 15 年的发展。我们讨论了基本等离子体物理过程，导致电子加速到与观察到的安静、离散的极光弧的发射相容的能量，极光弧定义为时间尺度为几分钟或更多，空间尺度范围从小于 1 公里到几十公里的弧。对于上下文，首先简要描述早期的观察结果。极光粒子加速的理论基础是基于等离子体的动力学理论，特别是平行电场的发展。这些平行电场可以沿着磁场线分布​​，通常与地磁场的镜面几何形状有关，或集中在狭窄的电荷分离区域，称为双层。观测表明，加速过程取决于磁场对齐的电流是远离地球、朝向地球，还是在通常与阿尔文波传播相关的电流混合区域。NASA 快速极光快照 (FAST) 卫星、ESA 卫星星座集群和日本 Reimei 卫星的最新观测结果为极光加速过程提供了新的见解，并进一步完善了极光粒子加速理论。或在通常与阿尔文波传播相关的电流混合区域。NASA 快速极光快照 (FAST) 卫星、ESA 卫星星座集群和日本 Reimei 卫星的最新观测结果为极光加速过程提供了新的见解，并进一步完善了极光粒子加速理论。或在通常与阿尔文波传播相关的电流混合区域。NASA 快速极光快照 (FAST) 卫星、ESA 卫星星座集群和日本 Reimei 卫星的最新观测结果为极光加速过程提供了新的见解，并进一步完善了极光粒子加速理论。