低杂波波谱的下移和可近性条件

本文利用改进磁面位移计算的射线轨迹Ｃｏｄｅ，研究在射线轨迹的第圈ｎ的下移以及下移量与各等离子体参量的关系。我们发现等离子体密度越高，波的频度越低，ｎ的下移量越大。计算表明：在射线的第一圈ｎ下移量的最大值大致与ｎ＾－ｅ／「ｆ＾１．５ｑ（ｒｃ）」成正比、也与电流、密度的分布和ｎ的初值等有关。

DOWNSHIFT OF LOWER HYBRID WAVE SPECTRUM AND ACCESSIBILITY

With a ray tracing code for improving the magnetic flux surface shift calculation. the relation between plasma parameters and the downshift of n in the first circle of trajectories is studied. The computations show that the higher the plasma density and the lower the driving frequency, the larger the downshift of n will be. The maximum of n downshift is proportional to and it is related to the profiles of plasma density and current, and the initial n. When the plasma density exceeds a critical value, the lower n waves with large amount of LHW power become inaccessible because of the downshift of n. This may be the reason why a density limit appears in the LHCD experiments.