惯性区低-β等离子体中的动力学Alfvén孤波

运用双流体MHD方程描述电子和离子的行为, 采用非扰动理论, 把孤子看作经典粒子, 通过推导的赝势(也称Sagdeev势)方程, 结合数值计算来研究惯性区低-β等离子体中动力学Alfvén孤波的特性. 结果表明离子热效应对Alfvén孤波特性的影响不可忽略, 且在惯性区稀疏型孤波和压缩型孤波均存在. 此结论与Freja卫星在极区上空所观测结果吻合很好. Alfvén孤波携带有平行电场, 它对带电粒子的加速有重要作用, 这给极光粒子加速提供了一种可能的物理机制.

SOLITARY KINETIC ALFVEN WAVES IN INERTIAL LIMIT REGION WITH LOW-β PLASMA

The characteristics of solitary kinetic Alfvén waves (SKAWs) in the low β　plasma of the inertial limit region (ILR) are studied. This study is based on the undisturbed theory. Two fluid magnetohydrodynamic（MHD）model is applied to describe ions and electrons motion, and the solitons are considered as the classical particles. The Sagdeev potential function is deduced in the light of the foundational equations and combining the numerical calculation. We find that the influence of hot ions on the properties of kinetic Alfvén waves cannot be neglected. We also find that both dip solitons and hump solitons exist in ILR. These results are in good agreement with the data observed by Freja satellite over the auroral region. The Alfvén solitary waves, accompanied by the parallel electric field, take an important part to accelerate the charge particles. This provides a possible physical mechanism for the acceleration of polar aurora in the auroral region.