Effects of boundary conditions and flow on the kink instability in a cylindrical plasma column
Effects of boundary conditions and flow on the kink instability in a cylindrical plasma column
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边界条件和流动对圆柱形等离子体柱扭结不稳定性的影响
DOI：
10.1063/1.2435306
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发表时间：
2007
影响因子：
2.2
通讯作者：
D. Ryutov
中科院分区：
文献类型：
--
作者：
I. Furno;T. Intrator;G. Lapenta;L. Dorf;S. Abbate;D. Ryutov
扭结不稳定性的实验研究是在一个线性等离子体柱，其中一端是线绑到等离子体源，和另一端是没有线绑，因此可以自由地在端板的表面上滑动。后一种边界条件是等离子体鞘层电阻的结果，该等离子体鞘层电阻至少部分地使等离子体与端板绝缘。螺旋m = 1扭结模式被观察到增长时，等离子体电流超过阈值，接近临界状态，其特征在于在自由轴向边界处具有最大位移的轴向模式结构。观察到的模式的方位角旋转，使螺旋扭结列总是拧到自由轴向边界。最近的扭结理论精确地再现了扭结模结构、旋转频率和不稳定性阈值[D。D. Ryutov等人，Phys.Plasmas 13，032105（2006）]，其包括轴向等离子体流和等离子体柱的一端，所述等离子体柱的一端由于实验验证的完美的非线绑定边界条件而自由移动。本文简要回顾了扭结理论及其对目前实验中有关边界条件的预测。
An experimental investigation of the kink instability is presented in a linear plasma column where one end is line-tied to the plasma source, and the other end is not line-tied and therefore free to slide over the surface of the end-plate. This latter boundary condition is a result of plasma sheath resistance that insulates, at least partially, the plasma from the end-plate. The helical m = 1 kink mode is observed to grow when the plasma current exceeds a threshold and, close to the criticality, is characterized by an axial mode structure with maximum displacement at the free axial boundary. Azimuthal rotation of the mode is observed such that the helically kinked column always screws into the free axial boundary. The kink mode structure, rotation frequency and instability threshold are accurately reproduced by a recent kink theory [D. D. Ryutov, et al., Phys. Plasmas 13, 032105 (2006)], which includes axial plasma flow and one end of the plasma column that is free to move due to a perfect non-line-tying boundary condition which is experimentally verified. A brief review of the kink theory and its predictions for the boundary conditions relevant in the present experiments are presented.