Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China.
Sci Rep. 2018 Jan 11;8(1):463. doi: 10.1038/s41598-017-18712-0.
When comets interacting with solar wind, straight and narrow plasma tails will be often formed. The most remarkable phenomenon of the plasma tails is the disconnection event, in which a plasma tail is uprooted from the comet's head and moves away from the comet. In this paper, the interaction process between a comet and solar wind is simulated by using a laser-driven plasma cloud to hit a cylinder obstacle. A disconnected plasma tail is observed behind the obstacle by optical shadowgraphy and interferometry. Our particle-in-cell simulations show that the difference in thermal velocity between ions and electrons induces an electrostatic field behind the obstacle. This field can lead to the convergence of ions to the central region, resulting in a disconnected plasma tail. This electrostatic-field-induced model may be a possible explanation for the disconnection events of cometary tails.
当彗星与太阳风相互作用时，通常会形成笔直而狭窄的等离子体尾流。等离子体尾流最显著的现象是断开事件，在此过程中，等离子体尾流会从彗星头部拔出并远离彗星。在本文中，我们使用激光驱动的等离子体云撞击圆柱障碍物来模拟彗星与太阳风的相互作用过程。通过光学阴影和干涉测量法在障碍物后面观察到断开的等离子体尾流。我们的粒子模拟结果表明，离子和电子之间的热速度差异会在障碍物后面产生一个静电场。该电场可以导致离子向中心区域汇聚，从而产生断开的等离子体尾流。这种静电场诱导的模型可能是彗星尾部断开事件的一种可能解释。
