OVERVIEW OF H-MODE STUDIES IN DIII-D

A major portion of the DIII-D program includes studies of the L-H tran sition, of the VH-mode, of particle transport and control and of the p ower-handling capability of a divertor. Significant progress has been made in all of these areas and the purpose of this paper is to summari ze the major results obtained during the last two years. An increased understanding of the origin of improved confinement in H-mode and in V H-mode discharges has been obtained, good impurity control has been ac hieved in several operating scenarios, studies of helium transport pro vide encouraging results from the point of view of reactor design, an actively pumped divertor chamber has controlled the density in H-mode discharges and a radiative divertor is a promising technique for contr olling the heat flux from the main plasma.