Role of ion acoustic instability in magnetic reconnection

We report on a first-principles numerical study of magnetic reconnection in plasmas with different initial ion-to-electron temperature ratios. In cases where this ratio is significantly below unity, we observe intense wave activity in the diffusion region, driven by the ion-acoustic instability. Our analysis shows that the dominant macroscopic effect of this instability is to drive substantial ion heating. In contrast to earlier studies reporting significant anomalous resistivity, we find that anomalous contributions due to the ion-acoustic instability are minimal. These results shed light on the dynamical impact of this instability on reconnection processes, offering new insights into the fundamental physics governing collisionless reconnection.

本研究针对具有不同初始离子-电子温度比的等离子体（plasma）中的磁重联（magnetic reconnection）开展第一性原理数值研究。当该温度比显著低于1时，我们在由离子声不稳定性（ion-acoustic instability）驱动的扩散区（diffusion region）内观测到强烈的波活动。我们的分析表明，该不稳定性的主导宏观效应为引发显著的离子加热。与此前报道存在显著反常电阻率（anomalous resistivity）的研究不同，我们发现离子声不稳定性带来的反常贡献极为微弱。上述结果阐明了该不稳定性对磁重联过程的动力学影响，为揭示支配无碰撞磁重联（collisionless reconnection）的基础物理机制提供了全新视角。