Alfven行波涌浪携带的场向电场──极光粒子加速机制

ALFVéN TRAVELLING SURGE WITH PARALLEL ELECTRIC FIELD──AURORAL PARTICLE ACCELERATION MECHANISM

提出一个剪切Ａｌｆｖｅｎ波加速极光粒子的新模式。频率远小于离子回旋频率的Ａｌｆｖｅｎ波由磁层向电离层传播会演化成孤波，当场向电流超过离子声不稳定性的临界电流时，激发离子声不稳定性，波与粒子的相互作用产生反常阻尼使Ａｌｆｖｅｎ波演化成行波涌浪。它携带一个方向向上的平行电场，加速极光电子形成分立极光。对等离子体密度、电场及其对应的电势进行了数值计算，结果发现满足磁层加速区条件形成Ａｌｆｖｎ行波涌浪，提供足够强的加速粒子的电场。

A new model for auroral particle acceleration produced by shear Alfven waves is put forward.The Alfven wave with frequence much lower than ion cyclotron frequence propagating from the magnetosphere to the ionosphere will evolve into a solitary wave.When field aligned current exceeds the critical limit of the ion acoustic instability,the anomalous resistance coming from the interaction between waves and particles makes the Alfven solitary wave a traveling surge.With a parallel upward electric field,it accelerates the auroral electrons and forms the discrete aurora.The numerical results of the plasma density,electric field and the corresponding potential show that the Alfven traveling surge can offer enough electric field for auroral paricles acceleration when the condition of the magnetosphere is met.