SURFACE AND DISCRETE ALFVEN WAVES IN A CURRENT CARRYING PLASMA
SURFACE AND DISCRETE ALFVEN WAVES IN A CURRENT CARRYING PLASMA
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载流等离子体中的表面波和离散阿尔文波
DOI：
10.1088/0741-3335/26/11/002
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发表时间：
1984
影响因子：
2.2
通讯作者：
I. Donnelly
中科院分区：
文献类型：
--
作者：
N. Cramer;I. Donnelly
最近研究表明，在等密度无电流等离子体和真空界面上传播的磁流体表面波受到有限频率效应的强烈影响，即欧姆定律中包含霍尔项。存在两种不同的模式，这取决于m的符号，即圆柱几何形状中的方位角模式数。作者将轴向等离子体电流的影响，并调查所产生的模式的色散关系的等离子体圆柱的均匀密度与可变的真空宽度。对于波频率ω <<ω i（离子回旋频率），电流在色散关系中引入相对于轴向波数k的符号的不对称性。一个不稳定的分支也出现了，与外部扭结模式。他们还发现了离散阿尔芬波（Alfven wave）的本征模，包括稳定的和不稳定的。然而，这些模式的存在强烈地依赖于磁场的剪切。在频率ω近似= ω i时，表面波不受电流的影响;然而，由于电流的影响，在极限频率以下消除了双模式或离子回旋波。
MHD surface waves propagating on the interface between a constant density current-free plasma and a vacuum have recently been shown to be strongly affected by finite frequency effects, i.e. the inclusion of the Hall term in the Ohm's Law. Two distinct modes exist, depending on the sign of m, the azimuthal mode number in cylindrical geometry. The authors incorporate the effects of an axial plasma current and investigate the dispersion relation of the resulting modes of a plasma cylinder of uniform density with variable vacuum width. For wave frequency omega << Omega i (the ion-cyclotron frequency) the current introduces an asymmetry in the dispersion relation with respect to the sign of k, the axial wavenumber. An unstable branch also appears, related to the external kink mode. They also find eigenmodes of the discrete Alfven wave (DAW), both stable and unstable. However, the existence of these modes depends strongly on the shear of the magnetic field. At frequency omega approximately= Omega i, the surface wave is not much affected by the current; however, the DAW modes, or ion-cyclotron waves, are eliminated below a limiting frequency due to the effects of the current.