论文标题
高马赫数的动力学准垂直冲击：MMS观察
The Dynamics of a High Mach Number Quasi-Perpendicular Shock: MMS Observations
论文作者
论文摘要
在极少数情况下，地球弓冲击的冲击参数可以接近超新星残留物预测的马赫数。我们介绍了使用磁层多尺度（MMS）航天器的多点测量值的高藻类马赫数（$ m_a = 27 $）的分析。我们发现，冲击动力学主要是由反射离子，它们产生的扰动以及扰动的非线性扩增驱动的。我们的分析表明，反射离子会在冲击的上游产生适度的磁增强，从而在横穿冲击脚时以非线性方式进化。它们可以转变为原始震动，这些原始震动以与磁场的小角度传播并朝弓冲击传播。非平稳弓冲击显示了改革和表面波纹的签名。我们的观察结果表明，尽管发生了冲击改革，但主冲击层永远不会消失。这些观察结果处于高血浆$β$，这是一种参数状态，数值模型尚未很好地探索。
Shock parameters at Earth's bow shock in rare instances can approach the Mach numbers predicted at supernova remnants. We present our analysis of a high Alfvén Mach number ($M_A= 27$) shock utilizing multipoint measurements from the Magnetospheric Multiscale (MMS) spacecraft during a crossing of Earth's quasi-perpendicular bow shock. We find that the shock dynamics are mostly driven by reflected ions, perturbations that they generate, and nonlinear amplification of the perturbations. Our analyses show that reflected ions create modest magnetic enhancements upstream of the shock which evolve in a nonlinear manner as they traverse the shock foot. They can transform into proto-shocks that propagate at small angles to the magnetic field and towards the bow shock. The nonstationary bow shock shows signatures of both reformation and surface ripples. Our observations indicate that although shock reformation occurs, the main shock layer never disappears. These observations are at high plasma $β$, a parameter regime which has not been well explored by numerical models.
