行星际结构与准平行无碰撞激波的相互作用

INTERACTION BETWEEN INTERPLANETARY STRUCTURE AND QUASI-PARALLEL COLLISIONLESS SHOCK

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。

Using an onerdimension hybrid code, we numerically studied the interachorbetween tWo kinds of interplanetary structures (the plasmoid with high density andinterpanetary shock) and the quasi-parallel collisionless shock. The results show thatdue to the scarering of large-amplitude ultralow-frequency upstream waves, theplasmoid with high density begins to diffuse in the upstream, and it diffusesconhnuously in the downstream besides a little compression when it passes through theshock ramp. When the interpanetary shock close to the quasiparallel collisionlessshock,large-amplitude ultralow-frequency waves are formed in the upstream of theinterplanetary shock, and the sbength of the interplanetary shock are enhanced. Finallythe two shocks merge as a new shock which excites large-amplitude ultralow-frequencywaves in the upstream.