Initial operation of the Wendelstein 7AS advanced stellarator

Abstract

The first plasma experiments on the W7AS advanced stellarator were conducted in October 1988, after magnetic surface mapping. The characteristics of the device are described. During the first phase of operation, 70 GHz ECF was used to generate and heat a 'currentless' plasma which was maintained in quasi-steady state for typically 0.5 s. Effects of the magnetic configuration on the confinement and measures to deal with the observed plasma current (bootstrap current and ECF-driven current) were investigated. Preliminary results of transport analysis are presented and compared with predictions of transport models.