Plasma Science and Fusion Center, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 USA.
Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637, USA.
Nat Commun. 2016 Oct 7;7:13081. doi: 10.1038/ncomms13081.
The remarkable discovery by the Chandra X-ray observatory that the Crab nebula's jet periodically changes direction provides a challenge to our understanding of astrophysical jet dynamics. It has been suggested that this phenomenon may be the consequence of magnetic fields and magnetohydrodynamic instabilities, but experimental demonstration in a controlled laboratory environment has remained elusive. Here we report experiments that use high-power lasers to create a plasma jet that can be directly compared with the Crab jet through well-defined physical scaling laws. The jet generates its own embedded toroidal magnetic fields; as it moves, plasma instabilities result in multiple deflections of the propagation direction, mimicking the kink behaviour of the Crab jet. The experiment is modelled with three-dimensional numerical simulations that show exactly how the instability develops and results in changes of direction of the jet.
钱德拉 X 射线观测站的一项重大发现表明，蟹状星云的喷流会周期性地改变方向，这给我们对天体物理喷流动力学的理解带来了挑战。有人认为，这种现象可能是磁场和磁流体动力学不稳定性的结果，但在受控的实验室环境中进行实验验证一直难以实现。在这里，我们报告了使用高功率激光产生等离子体喷流的实验，这些喷流可以通过明确定义的物理比例定律与蟹状星云喷流直接进行比较。喷流产生其自身嵌入的环形磁场；当它移动时，等离子体不稳定性会导致传播方向的多次偏折，模拟出蟹状星云喷流的扭结行为。该实验通过三维数值模拟进行建模，这些模拟准确地展示了不稳定性是如何发展并导致喷流方向发生变化的。
