Analytic Study of Density Limit Mechanism for Tokamak Lower Hybrid Current Drive Experiments

• 来源期刊: 中国物理快报（英文版）
• 学科: 物理学
• 年，卷（期）: 2001,（2）
• 页码范围: 251-253
• 页数: 3页
• 分类号: O4
• 语种: 英文

摘要

The dispersion relation of the lower hybrid wave in the tokamak current drive regime (ω ＞ 2ωLH, where ωLH is the lower hybrid frequency) is analysed. Toroidicity effects can shift the parallel refractive index upward or downward. The downward shift will lead to a mode conversion from the slow wave to the fast wave. It is indicated that this is the main mechanism limiting the effectiveness of tokamak lower hybrid current drive. Accordingly, a sufficient condition is obtained for the wave penetration, corresponding to a critical density, which is proportional to f4/3B2/3(A)4/3, with f being the wave frequency, B the magnetic field strength and A the aspect ratio. Quantitative agreement with experiments is found.X