Particle Control and Plasma Performance in the Lithium Tokamak Experiment (LTX)

Abstract

Abstract. The Lithium Tokamak eXperiment (LTX) is a small, low aspect ratio tokamak, 1 which is fitted with a stainless steel-clad copper liner, conformal to the last closed flux surface. The liner can be heated to 350 °C. Several gas fueling systems, including supersonic gas injection, and molecular cluster injection have been studied, and produce fueling efficiencies up to 35%.Discharges are strongly affected by wall conditioning. Discharges without lithium wall coatings are limited to plasma currents of order 10 kA, and discharge durations of order 5 msec. With solid lithium coatings discharge currents exceed 70 kA, and discharge durations exceed 30 msec.Heating the lithium wall coating, however, results in a prompt degradation of the discharge, at the melting point of lithium. These results suggest that the simplest approach to implementing liquid lithium walls in a tokamak -thin, evaporated, liquefied coatings of lithium -does not produce an adequately clean surface.2