Sheath wave propagation in a magnetoplasma
Sheath wave propagation in a magnetoplasma
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磁等离子体中的鞘波传播
DOI：
10.1029/rs024i003p00289
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
K. Balmain
中科院分区：
文献类型：
--
作者：
J. Laurin;G. Morin;K. Balmain
提出了一种关于集中在将平面导体与冷磁等离子体分隔开的真空隙鞘层区域内的电磁波传播的理论。所施加的静磁场平行于导体且与波传播方向相同。该理论预测在零到上混合频率除以√2之间的所有频率下都能传播。报道了一些实验结果，其中利用与磁场对齐的细圆柱天线端部的波反射所引起的共振来确定鞘层波的色散关系。通过实验研究了天线偏压、等离子体密度和天线直径对色散关系的影响，并将结果与平面理论进行了比较。尽管理论和实验的几何形状存在差异，但在磁场、等离子体密度、鞘层厚度和天线半径的变化方面注意到了定性的一致性。理论预测施加磁场会提高鞘层波的截止频率，这一点已通过实验得到证实，同时鞘层的存在允许在回旋频率之上传播这一预测也得到了证实。特别是，理论和实验都表明在回旋频率附近存在一个特殊频率，在该频率下鞘层波波数与等离子体密度无关。
A theory is presented for propagation of electromagnetic waves concentrated in the vacuum-gap sheath region separating a plane conductor from a cold magnetoplasma. The applied static magnetic field is parallel to the conductor and in the direction of wave propagation. The theory predicts propagation at all frequencies between zero and the upper-hybrid frequency divided by √2. Experimental results are reported in which resonances caused by the wave reflection at the end of a thin cylindrical antenna aligned with the magnetic field are used to determine the sheath-wave dispersion relation. The effect of the antenna bias, plasma density and antenna diameter on the dispersion relation are studied experimentally and the results are compared with the plane-surface theory. In spite of the difference between the theoretical and experimental geometries, qualitative agreement is noted with respect to variations in magnetic field, plasma density, sheath thickness and antenna radius. The prediction that the presence of an applied magnetic field raises the upper sheath wave cutoff frequency has been confirmed experimentally, as well as the prediction that the presence of the sheath allows propagation above the cyclotron frequency. In particular, both theory and experiment show the existence near the cyclotron frequency of a special frequency at which the sheath-wave wave number is independent of the plasma density.