Rapid Current Ramp-Up by Cyclotron-Driving Electrons beyond Runaway Velocity

Abstract

The toroidal current has been rapidly ramped-up after the formation of an initial closed flux surface in an electron cyclotron heated discharge in the low aspect ratio torus experiment device. A current carrying fast electron tail is developed well beyond the runaway velocity against the reverse voltage from self-induction, suggesting a forward driving force on the tail by the cyclotron absorption of high N(parallel) electron Bernstein waves.