Experimental Study of Edge Plasma Structure in Various Discharges on Compact Helical System

摘要

Precise measurements of edge density profiles in various discharges have been performed successfully in the compact helical system (CHS) with a thermal neutral lithium beam probe. During high beta discharges, an outward shift of the plasma edge boundary was observed with an increase in the beta value, which was found to agree qualitatively with theoretical calculations. Experiments with different magnetic field configurations, i.e., with limiter, divertor and with an m/n=1/1 island, were also performed. Clear difference in the edge density profiles= among the configurations and a large change of plasma parameters in the configuration with the m/n= l/1 island were observed.