论文标题
具有剪切流的磁化等离子体的精确杂交运动平衡
Exact hybrid-kinetic equilibria for magnetized plasmas with shearing flows
论文作者
论文摘要
语境。以剪切流为特征的磁化等离子体在许多自然环境中都存在,例如地球的磁性和太阳风。涉及等离子体的无碰撞性质需要动力学描述。当剪切层的宽度是离子尺度的顺序时,可以采用混合Vlasov-Maxwell方法。目标。本文的目的是在混合Vlasov-Maxwell描述中为带有平面剪切流的磁化等离子体的固定配置提供明确的形式。考虑了两种配置:第一个具有均匀磁场的稳定性磁场相对于散装速度;第二个具有均匀磁性可变方向磁场的磁场。方法。固定离子分布函数是通过将动作的单粒子常数组合而成的,该运动是衍生研究粒子动力学的。考虑到背景电磁场的局部近似值,分析得出了有关分布函数形式的初步信息。然后,设置了数值方法以获得通用概况的解决方案。结果。发现的显式分布函数允许获得密度,散装速度,温度和热通量的曲线。还评估了分布函数中各向异性和天性的。在数值模拟期间的溶液的平稳性在均匀的斜磁场情况下检查。结论。在开尔文 - 霍尔莫茨不稳定性的模拟中,所考虑的配置可以用作地球磁磁的模型。
Context. Magnetized plasmas characterized by shearing flows are present in many natural contexts, such as the Earth's magnetopause and the solar wind. The collisionless nature of involved plasmas requires a kinetic description. When the width of the shear layer is of the order of ion scales, the Hybrid Vlasov-Maxwell approach can be adopted. Aims. The aim of the paper is to derive explicit forms for stationary configurations of magnetized plasmas with planar shearing flows,within the Hybrid Vlasov-Maxwell description. Two configurations are considered: the first with a uniform magnetic field obliquely directed with respect to the bulk velocity; and the second with a uniform-magnitude variable-direction magnetic field. Methods. Stationary ion distribution functions are obtained by combining single-particle constant of motions, which are derived studying particle dynamics. Preliminary information about the form of the distribution functions are analytically derived considering a local approximation for the background electromagnetic field. Then, a numerical method is set up to obtain a solution for general profiles. Results. The explicit distribution functions that are found allow to obtain profiles of density, bulk velocity, temperature and heat flux. Anisotropy and agyrotropy in the distribution function are also evaluated. Stationarity of the solution during numerical simulations is checked in the uniform oblique magnetic field case. Conclusions. The considered configurations can be used as models for the Earth's magnetopause in simulations of the Kelvin-Helmholtz instability.