等离子体湍动对准垂直激波中粒子加速的影响

本文利用试验粒子方法研究了在考虑等离子体湍动的情况下带电粒子在准垂直激波中的加速, 在计算中, 我们采用组合模型来拟合等离子体湍动. 计算结果表明, 在存在等离子体湍动的情况下, 粒子可横越背景磁场运动, 从而被激波反射的上游粒子在到达下游后可被等离子体湍动散射回到上游, 并再次被激波反射并加速, 这样的过程可重复很多次, 因而粒子可被加速到很高的能量. 我们还研究了激波角, 粒子的初始能量和等离子体湍动的强度, 以及相干长度和两种湍动组分强度比与加速粒子的能谱之间的关系.

Particle acceleration at shock waves with composite turbulence

With test particle simulations, considering plasma turbulence and fitting the plasma turbulence with composite turbulence model, we investigate the particle acceleration at perpendicular shocks. The simulation results show that, under consideration of plasma turbulence, particles can traverse the background magnetic field. Therefore, the particles reflected by shock waves may be scattered back to upstream for several or many times, so they become energetic particles easily. Meanwhile the correlations between energy spectra of particles and θ_Bn, the strength of plasma turbulence, coherence length, initial energy particle and the ratio of the strength of 1D to 2D turbulence are studied.