TOROIDAL PLASMA CURRENT SUSTAINMENT BY LOWER HYBRID WAVES IN THE WT-2 TOKAMAK

Abstract

By injecting rf power P/sub rf/ near the lower hybrid frequency into an Ohmically heated plasma near the end of tokamak discharge in the WT-2, an rf-driven current-sustained plasma is produced and continues to exist during the rf injection period, the toroidal current (I/sub p/approx.10 kA) being generated by the lower hybrid wave only without the Ohmic power. The efficiency of rf-driven current generation is high and attains I/sub p//P/sub rf/roughly-equal0.9 kA/kW at the plasma density n/sub e/approx. =1.4 x 10/sup 12/ cm/sup -3/, with somewhat lower efficiency at higher density.