二维静电孤立波的粒子模拟研究

利用二维粒子模拟程序研究了双流不稳定性激发静电波并演化为静电孤立波的物理过程.计算结果表明,在线性增长阶段,主要激发的是沿磁场传播的静电波;在非线性演化阶段,相邻的静电波会互相合并,直至形成静电孤立波,并可激发静电哨声波.还研究了磁场强度和离子温度对此过程的影响.当磁场强度比较小时,无法形成静电孤立波,只有磁场强度达到一定程度后静电孤立波才能形成;同时,离子温度会影响静电孤立波的稳定性,当离子温度比较小时,静电孤立波的稳定性减弱,在演化一段时间后会逐渐瓦解. 

2D Particle-in-Cell Simulations on Electrostatic Solitary Waves

With two-dimensional (2D) particle-in-cell simulations, the excitation of electrostatic waves by two-beam instability, and their nonlinear evolution into the electrostatic solitary waves are investigated. The simulation results indicate that the electrostatic waves excited in linear growth stage propagate mainly along the magnetic field. These waves coalesce with each other and form electrostatic solitary waves, and at the same time they can generate electrostatic whistlers. Moreover, we have also surveyed the influence of the strength of the magnetic field and the ion temperature on this process. Electrostatic solitary waves cannot form when the strength of the magnetic field is weak. Only if the strength of the magnetic field is sufficiently strong can the electrostatic waves form. Meanwhile, the ion temperature can affect the stability of electrostatic solitary waves. When the ion temperature is low, the stability of electrostatic solitary waves decrease and they will break up gradually.