Rf Current Drive in a Tokamak Plasma by the Lower Hybrid Wave in Jipp T-2

摘要

A current driven by injecting the lower hybrid wave was observed in a Tokamak of low density. It is confirmed that RF-driven current is generated by momentum transfer of the lower hybrid wave propagating with small parallel refractive index to runaway electrons beyond the critical velocity. The efficiency of the current generation is 1 kA/kW with an RF power of 40 kW. When cyclotron emission due to RF-driven runaway electrons increases suddenly, spikes and bursts in loop voltage and X-rays appear coincidentally. In long rf pulse, these rapid changes progress to relaxation oscillations. It is concluded that the pulsating changes originate in the instantaneous scattering of runaway electrons by the unstable waves excited at the anomalous Doppler resonance.