与Richtmyer-Meshkov不稳定性相关的磁场放大
Magnetic Field Amplification Associated with the Richtmyer-Meshkov Instability
摘要：
用二维MHD模拟方法研究了Richtmyer-Meshkov不稳定性（RMI）对磁场的放大作用。单模分析揭示了RMI的非线性演化与场增强之间的关系。研究发现，周围的磁场被与RMI相关的流体运动拉伸，其强度被显著放大两个数量级以上。磁场的饱和程度取决于激波通过后放大的磁压和热压之间的平衡。这种有效的放大作用可以在一个很宽的RMI条件范围内实现，例如入射激波的马赫数和接触间断处的密度比。结果表明，RMI可能是一个强大的星际磁场的放大机制，并导致在超新星遗迹的冲击观测到的局部强场的起源。
英文摘要：
The amplification of a magnetic field due to the Richtmyer-Meshkov instability (RMI) is investigated by two-dimensional MHD simulations. Single-mode analysis is adopted to reveal definite relation between the nonlinear evolution of RMI and the field enhancement. It is found that an ambient magnetic field is stretched by fluid motions associated with the RMI, and the strength is amplified significantly by more than two orders of magnitude. The saturation level of the field is determined by a balance between the amplified magnetic pressure and the thermal pressure after shock passage. This effective amplification can be achieved in a wide range of the conditions for the RMI such as the Mach number of an incident shock and the density ratio at a contact discontinuity. The results suggest that the RMI could be a robust mechanism of the amplification of interstellar magnetic fields and cause the origin of localized strong fields observed at the shock of supernova remnants.
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