行星际结构与准平行无碰撞激波的相互作用

应用一维混合模拟方法数值研究了高密度等离子体团和行星际激波与准平行无碰撞激波的相互作用．结果表明，由于推平行无碰撞激波上游的大振幅低频波动的散射，除了在通过激波过渡区时稍有压缩外，等离子体团从激波的上游开始就一直是不断弥散的．行星际激波在向准平行无碰撞激波靠近的过程中，会在其上游产生大振幅的低频波动，同时行星际激波的强度不断增加，最后和准平行无碰撞激波会并成一个新的激波，在新激波前继续有大振幅的低频波动产生     

行星际结构与垂直无碰撞激波的相互作用

应用一维混合模拟方法数值研究了两种行星际结构──反向磁场和高密度等离子团与垂直无碰撞激波的相互作用．结果表明，随着激波上游区磁场的反向，下游区磁场将逐渐改变符号，且等离子体密度和速度分别呈现较强的湍动．激波上游和下游的物理量依然满足Rankine-Hugonoit关系．当高密度的等离子体团通过垂直无碰撞激波时，部分质子被激波反射，部分质子被加速并进入下游区域．由于质子速度分布为非Maxwell分布，在激波下游也激发出较强的湍动．     

Cluster observations of earthward propagating plasmoid and flux ropes in the near-tail during the course of a substorm event

We analyze the magnetic structures in the near-tail at Xgsm = −17.5 Re on September 19, 2003 by Cluster. During the course of a substorm event, the earthward propagating plasmoid and flux ropes in the near-tail are observed. The earthward propagating plasmoid is associated with the bipolar Bz and By signatures. The two flux ropes are embedded within the earthward plasma flows, which might be referred to the population as ‘‘BBF-type’’ flux ropes. The first flux rope diameter is about 0.7 Re and duration based upon the Bz signature is ∼20 s, while the second one diameter is about 1.4 Re and duration is ∼30 s. The earthward propagating plasmoid and flux ropes could have influence upon the dipolarization and injection in inner magnetosphere. The Cluster observations of earthward propagating plasmoid and flux ropes can be interpreted as strong evidence for multiple X-lines. Our observations are consistent with that multiple plasmoids or flux ropes are formed repeatedly and ejected tailward in the course of geomagnetically active time.