Magnetic reconnection in quasi-parallel shocks, relevant to the Earth's bow shock, is studied by means of two-dimensional full particle-in-cell simulations. As the Alfvenic Mach number increases, the propagation direction of the waves excited in the transition region changes, and the shock becomes more turbulent with more reconnection sites. In the higher Mach number shock, abundant electron-only reconnection sites are generated with scales on the order of the ion skin depth or less. Non-reconnecting current sheets can also generate electron jets and energy dissipation can occur there as well. However, non-reconnecting current sheets with the magnetic field reversal typically show a smaller energy dissipation rate than reconnecting current sheets. In the shock transition region, two types of waves are responsible for driving reconnection: one has a wavelength around three ion skin depths (di), and the other has a wavelength less than 1 di. Electron and ion distribution functions show that in regions where the former type of waves is excited, there are two ion beams and a single-peaked electron distribution. In contrast, in regions where the latter type of waves is excited, there are multiple electron and ion beams. The waves propagating obliquely to the magnetic field bend the magnetic field lines, and magnetic reconnection occurs where oppositely directed field lines come into contact.

中文翻译：

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地球准平行弓形激波产生的磁重联和动波

与地球弓形激波相关的准平行激波中的磁重联通过二维全粒子胞内模拟进行研究。随着阿尔芬马赫数的增加，在过渡区激发的波的传播方向发生变化，激波变得更加湍流，重联点更多。在更高的马赫数激波中，会产生大量的纯电子重联位点，其尺度与离子趋肤深度或更小。非重新连接的电流片也可以产生电子射流，并且在那里也会发生能量耗散。然而，具有反向磁场的非重新连接电流片通常比重新连接电流片显示出更小的能量耗散率。在激波过渡区，有两种类型的波负责驱动重新连接：一个具有大约三个离子趋肤深度 (di) 的波长，另一个的波长小于 1 di。电子和离子分布函数表明，在前一种波被激发的区域，有两个离子束和一个单峰电子分布。相比之下，在激发后一种波的区域，有多个电子束和离子束。与磁场倾斜传播的波使磁场线弯曲，并且在相反方向的磁场线接触的地方发生磁重联。在后一种波被激发的区域，有多个电子和离子束。与磁场倾斜传播的波使磁场线弯曲，并且在相反方向的磁场线接触的地方发生磁重联。在后一种波被激发的区域，有多个电子和离子束。与磁场倾斜传播的波使磁场线弯曲，并且在相反方向的磁场线接触的地方发生磁重联。