Parameters for lower hybrid current drive in tokamaks

Parameters for lower hybrid current driven tokamaks are investigated using fundamental criteria of mode conversion, accessibility and parametric instability. The density limit obtained experimentally is analysed by applying the criteria ω0/ωLH > x0 and ωpe/ωce < y0, where ω0 is the frequency of the injected power, ωLH is the lower hybrid frequency, ωpe is the electron plasma frequency, ωce is the electron cyclotron frequency and x0, y0 are the given numerical factors. It is demonstrated that the parameter space for lower hybrid current drive in tokamaks is divided into two regions, dominated by the parametric instability and by accessibility.

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