STUDY OF ELECTROMAGNETIC RADIATION FROM ELECTROSTATIC' SOLITARY WAVES IN SPACE PLASMAS

我们发展了一种新的方法，以实现一个有效的吸收边界的电磁粒子模拟与最小尺寸的阻尼区。我们还提出了一种新的计算电流密度的电荷守恒法，大大减少了计算量。我们已经证明了存在的高次谐波朗缪尔波增强的电子束由一个新开发的Vlasov代码。在一个开放的系统中的吸收边界，我们跟踪了长时间和长距离的电子束不稳定性的演变，显示静电孤立波的形成和它们的耦合与斜哨声波和较低的，混合波，这是本地化的区域靠近电子束生成区域。在二维系统中，我们发现静电孤立波伴随着电磁分量，由于局部电流驱动的ExB漂移与二维静电势的垂直电场。我们发现了一个电子束的形成，通过布尼曼不稳定性驱动的感应电场的磁层边界层。从理论上分析了静电波的结构和特性，并将其推广到三维模型。得到了孤立三维势存在的必要条件。

We have developed a new method to realize an efficient absorbing boundary for ele'ctro hagnetic particle simulations with a minimal size of the damping region. We have also developed a new algorithm of the charge conservation method for current density calculation, which substantially reduced the computation. We have demonstrated existence of higher harmonics of Langmuir waves enhanced by an electron beam by a newly developed Vlasov code. In an open system with the absorbing boundaries, we traced a long time and long distance evolution of the electron beam instability, showing formation of electrostatic solitary waves and their coupling with oblique whistler waves and lower, hybrid waves, which are localized in the region close to the electron beam generation region. In the two dimensional system, we find the electrostatic solitary waves are accompanied by electromagnetic components due to the localized current driven by the ExB drift associated with the perpendicular electric field of two-dimensional electrostatic potentials. We found an electron beam formation through Buneman instability driven by an induced electric field in the boundary layers of the magnetosphere. The structure and characteristics of electrostatic waves were analyzed theoretically, and the analysis was also extended to a three dimensional model. We obtained the necessary conditions for existence of isolated three-dimensional potentials.