Characterizing velocity–space signatures of electron energization in large-guide-field collisionless magnetic reconnection
Characterizing velocity–space signatures of electron energization in large-guide-field collisionless magnetic reconnection
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DOI：
10.1063/5.0082213
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发表时间：
2021-12
影响因子：
2.2
通讯作者：
A. McCubbin;G. Howes;J. TenBarge
中科院分区：
文献类型：
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作者：
A. McCubbin;G. Howes;J. TenBarge
磁重联在无碰撞等离子体中磁能的释放和粒子的碰撞中起着重要的作用。无碰撞磁场重联中的能量转移本质上是一个两步过程：电场对粒子的可逆、无碰撞，然后是该能量的碰撞热化，导致不可逆的等离子体加热。回旋动力学数值模拟被用来探索电子回旋的第一步，我们产生的场粒子相关签名的电子回旋在2D强引导场无碰撞磁场重联的第一个例子。我们确定这些速度空间签名在x点和排气中，重联几何的区域中，电子的碰撞主要发生。这些速度空间签名的建模表明，在强引导场的限制下，电子的重连通过平行电场驱动重连的面外电子流的体加速发生，这是重连的非共振机制。我们探索这些速度空间签名的变化在等离子体β范围[公式：见正文]。我们的分析超越了等离子体动力学的流体图像，并利用排气区电子束的动力学特征，提出了一个单点诊断，它可以潜在地识别使用航天器观测的重连排气区。
Magnetic reconnection plays an important role in the release of magnetic energy and consequent energization of particles in collisionless plasmas. Energy transfer in collisionless magnetic reconnection is inherently a two-step process: reversible, collisionless energization of particles by the electric field, followed by collisional thermalization of that energy, leading to irreversible plasma heating. Gyrokinetic numerical simulations are used to explore the first step of electron energization, and we generate the first examples of field–particle correlation signatures of electron energization in 2D strong-guide-field collisionless magnetic reconnection. We determine these velocity space signatures at the x-point and in the exhaust, the regions of the reconnection geometry in which the electron energization primarily occurs. Modeling of these velocity–space signatures shows that, in the strong-guide-field limit, the energization of electrons occurs through bulk acceleration of the out-of-plane electron flow by the parallel electric field that drives the reconnection, a non-resonant mechanism of energization. We explore the variation of these velocity–space signatures over the plasma beta range [Formula: see text]. Our analysis goes beyond the fluid picture of the plasma dynamics and exploits the kinetic features of electron energization in the exhaust region to propose a single-point diagnostic, which can potentially identify a reconnection exhaust region using spacecraft observations.