Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
Nat Commun. 2015 Feb 4;6:6190. doi: 10.1038/ncomms7190.
Magnetic reconnection, the annihilation and rearrangement of magnetic fields in a plasma, is a universal phenomenon that frequently occurs when plasmas carrying oppositely directed field lines collide. In most natural circumstances, the collision is asymmetric (the two plasmas having different properties), but laboratory research to date has been limited to symmetric configurations. In addition, the regime of strongly driven magnetic reconnection, where the ram pressure of the plasma dominates the magnetic pressure, as in several astrophysical environments, has also received little experimental attention. Thus, we have designed the experiments to probe reconnection in asymmetric, strongly driven, laser-generated plasmas. Here we show that, in this strongly driven system, the rate of magnetic flux annihilation is dictated by the relative flow velocities of the opposing plasmas and is insensitive to initial asymmetries. In addition, out-of-plane magnetic fields that arise from asymmetries in the three-dimensional plasma geometry have minimal impact on the reconnection rate, due to the strong flows.
磁重联是等离子体中磁场的湮灭和重新排列，是一种普遍现象，当携带相反方向磁场线的等离子体碰撞时经常发生。在大多数自然情况下，碰撞是不对称的（两个等离子体具有不同的性质），但迄今为止的实验室研究仅限于对称配置。此外，在某些天体物理环境中，磁场压力被等离子体的冲击压力所主导的强烈驱动磁重联区域也很少受到实验关注。因此，我们设计了实验来探测不对称、强烈驱动、激光产生的等离子体中的磁重联。在这里，我们表明，在这个强烈驱动的系统中，磁场通量的湮灭速率取决于相反等离子体的相对流动速度，并且对初始不对称性不敏感。此外，由于强流的存在，来自三维等离子体几何形状不对称的面外磁场对重联速率的影响最小。
