Electron cyclotron wave heating studies on the CT-6B tokamak

An electron cyclotron wave heating experiment at marked downshift of the resonance frequency has been performed on a small device, the CT-6B tokamak. The authors found that there are obvious heating effects within a very wide range of the central toroidal field values, even up to ωce/ω approx. = 2. It is suggested that anomalous absorption of microwave power due to non-linear wave conversion is a possible heating mechanism. Resonance absorption at the downshifted frequency due to a Doppler shift may play a certain role. The experimental results indicate that it is possible to heat existing large tokamaks which have a higher toroidal field of several teslas with a currently available gyrotron. In numerical computation, the authors use ray tracing to study the energy deposition of waves in the CT-6B tokamak plasma. (author). 4 refs, 2 figs