Electron Cyclotron Resonance-Preionization in the WT-1 Tokamak

Injecting a high power microwave into the WT-1 toroidal device, production mechanism of toroidal plasma at the electron cyclotron resonance (ECR) is studied experimentally. Such ECR-plasma is used as microwave preionization of tokamak discharge. It is shown that ECR-preionization is useful for the reduction of loop voltage in the early stage, and the suppression of production of runaway electrons and hard X-ray in the quasi-steady stage.