带有准平行磁场的电子-离子等离子体的温和相对论碰撞的粒子模拟：超新星冲击时的电子加速和磁场放大
Particle-in-cell simulation of a mildly relativistic collision of an electron-ion plasma carrying a quasi-parallel magnetic field: Electron acceleration and magnetic field amplification at supernova shocks
摘要：
接近SNR冲击的等离子体过程导致磁场的放大和电子的加速，将它们注入扩散加速机制。本文研究了由电子和离子组成的两个等离子体云以0.5c的速度碰撞时电子的加速和B场的放大。一个准平行的引导磁场，云密度比为10和等离子体温度为25 keV被认为是。在稠密等离子体云的前部形成准平面激波。它是由具有沿引导磁场的电场分量的圆左旋偏振电磁波介导的。它的传播方向接近于引导场的传播方向，并与碰撞边界正交。它具有低频率和等于离子惯性长度的几倍的波长，这将指示接近左手模式（离子哨声）的离子回旋共振频率的色散阿尔芬波，只要频率是适当的。然而，它以超阿尔芬等离子体碰撞速度移动，这表明它是阿尔芬先驱或非线性MHD波，如短大振幅磁结构（SLAMS）。这种波的磁振幅的增长值远远超过准平行引导场和平行模式的结果在准垂直冲击。我们提出的证据，这种模式的不稳定性的四波相互作用。在稠密云上游发展的波引起碰撞边界前的电子加速。离子和电子之间的能量均分建立在冲击和电子被加速到相对论速度。
英文摘要：
Plasma processes close to SNR shocks result in the amplification of magnetic fields and in the acceleration of electrons, injecting them into the diffusive acceleration mechanism. The acceleration of electrons and the B field amplification by the collision of two plasma clouds, each consisting of electrons and ions, at a speed of 0.5c is investigated. A quasi-parallel guiding magnetic field, a cloud density ratio of 10 and a plasma temperature of 25 keV are considered. A quasi-planar shock forms at the front of the dense plasma cloud. It is mediated by a circularly left-hand polarized electromagnetic wave with an electric field component along the guiding magnetic field. Its propagation direction is close to that of the guiding field and orthogonal to the collision boundary. It has a low frequency and a wavelength that equals several times the ion inertial length, which would be indicative of a dispersive Alfven wave close to the ion cyclotron resonance frequency of the left-handed mode (ion whistler), provided that the frequency is appropriate. However, it moves with the super-alfvenic plasma collision speed, suggesting that it is an Alfven precursor or a nonlinear MHD wave such as a Short Large-Amplitude Magnetic Structure (SLAMS). The growth of the magnetic amplitude of this wave to values well in excess of those of the quasi-parallel guiding field and of the filamentation modes results in a quasi-perpendicular shock. We present evidence for the instability of this mode to a four wave interaction. The waves developing upstream of the dense cloud give rise to electron acceleration ahead of the collision boundary. Energy equipartition between the ions and the electrons is established at the shock and the electrons are accelerated to relativistic speeds.
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