The generalized accessibility and spectral gap of lower hybrid waves in tokamaks
The generalized accessibility and spectral gap of lower hybrid waves in tokamaks
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DOI：
10.1063/1.870624
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发表时间：
1994-03
影响因子：
2.2
通讯作者：
H. Takahashi
中科院分区：
文献类型：
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作者：
H. Takahashi
利用冷等离子体色散关系和各种几何约束（GC）关系，研究了低混杂波的广义可达性，其中包括平行折射率（n）的向上或向下移动.结果表明，n的upshifting是有界的，可以是不足以桥接一个大的频谱间隙，造成波阻尼，如果GC关系不允许发生斜共振。传统的基于磁力线俯仰角的n阶升档机制与实验观测结果相矛盾。提出了一种由沿沿着场线的密度梯度引起的上移机制，这与实验观察并不矛盾，并对低杂波理论中一些尚未解决的问题，包括“种子电子”的产生，提供了合理的解释。
The generalized accessibility of lower hybrid waves, which may include shifting of the parallel refractive index (n∥), either upward or downward, is investigated, using the cold plasma dispersion relation and various geometrical constraint (GC) relations imposed on the behavior of n∥. It is shown that n∥ upshifting is bounded and can be insufficient to bridge a large spectral gap to cause wave damping, if the GC relation does not allow the oblique resonance to occur. The traditional n∥ upshift mechanism based upon the pitch angle of magnetic field lines is shown to lead to contradictions with experimental observations. An upshift mechanism brought about by the density gradient along field lines is proposed, which is not inconsistent with experimental observations, and provides plausible explanations to some unresolved issues of lower hybrid wave theory, including generation of ‘seed electrons.’