| Original Articles |
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Analytic Study of Density Limit Mechanism for Tokamak Lower
Hybrid Current Drive Experiments |
| SHI Bing-Ren |
| Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041 |
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| Cite this article: |
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SHI Bing-Ren 2001 Chin. Phys. Lett. 18 251-253 |
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Abstract 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.
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| Keywords:
52.35.Hr
52.40.Db
52.55.Fa
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Published: 01 February 2001
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| PACS: |
52.35.Hr
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(Electromagnetic waves (e.g., electron-cyclotron, Whistler, Bernstein, upper hybrid, lower hybrid))
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52.40.Db
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(Electromagnetic (nonlaser) radiation interactions with plasma)
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52.55.Fa
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(Tokamaks, spherical tokamaks)
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