标题： 快速磁声波在磁重联区域附近的反射 显示英文标题

标题： Reflection of fast magnetosonic waves near magnetic reconnection region

摘要： 太阳日冕中的磁重联被认为容易形成多个相互作用的等离子体团，以前的研究表明，等离子体团动力学可以触发不同模式的磁流体波，从重联区域向外传播。 然而，在日冕重联区域附近的等离子体参数和磁场强度的变化可能导致波的反射和模式转换。 在本文中，我们研究了重联区域附近快速磁声波的反射和折射。 在合理假设了解析指定的阿尔芬速度剖面的情况下，我们推导并解析求解了非均匀背景等离子体中快速模波传播的完整波动方程，而无需使用小波长近似。 我们表明，由于阿尔芬速度梯度，波在重联电流片附近发生反射，并且反射效率取决于等离子体-$\beta$参数以及波的频率。 特别是，我们发现，在低-$\beta$等离子体中，重联区域附近的波反射更有效，这在太阳日冕条件下是典型的。 此外，低频波的反射更大，而高频波几乎不经过反射就从重联区域向外传播。 我们讨论了在强磁场日冕等离子体中，磁重联区域附近高效波反射对粒子加速的影响，以及这些波的动量力在色球层中对第一电离势（FIP）分馏可能产生的影响。 显示英文摘要

摘要： Magnetic reconnection in the solar corona is thought to be unstable to the formation of multiple interacting plasmoids, and previous studies have shown that plasmoid dynamics can trigger MHD waves of different modes propagating outward from the reconnection site. However, variations in plasma parameters and magnetic field strength in the vicinity of a coronal reconnection site may lead to wave reflection and mode conversion. In this paper we investigate the reflection and refraction of fast magnetoacoustic waves near a reconnection site. Under a justified assumption of an analytically specified Alfv\'{e}n speed profile, we derive and solve analytically the full wave equation governing propagation of fast mode waves in a non-uniform background plasma without recourse to the small-wavelength approximation. We show that the waves undergo reflection near the reconnection current sheet due to the Alfv\'en speed gradient and that the reflection efficiently depends on the plasma-$\beta$ parameter as well as on the wave frequency. In particular, we find that waves are reflected more efficiently near reconnection sites in a low-$\beta$ plasma which is typical for the solar coronal conditions. Also, the reflection is larger for lower frequency waves while high frequency waves propagate outward from the reconnection region almost without the reflection. We discuss the implications of efficient wave reflection near magnetic reconnection sites in strongly magnetized coronal plasma for particle acceleration, and also the effect this might have on First Ionization Potential (FIP) fractionation by the ponderomotive force of these waves in the chromosphere.