Effects of carbonization on the confinement properties of the DIII-D H-mode.

摘要

Understanding and increasing the energy confinement time ((tau)(sub E) (triple bond) W(sub T)/P(sub T)) remains a primary goal a fusion research. A primary technique utilized to increase (tau)(sub E) within a given machine is to operate at a higher plasma current. Although Z(sub eef) in DIII-D is generally (le)2, high radiated power (P(sub rad)/P(sub T) (ge) 0.6) and metal accumulation have been observed during high current (I(sub p) (ge) 2 MA) beam heated D(sup 0) (yields) D(sup +) H-mode discharges. Reduction of metallic impurity influx has been obtained on numerous tokamaks with the introduction of a thin carbon film. This paper reports the successful carbonization of the DIII-D vacuum vessel which allowed for routine high current operation, and it examines the confinement properties of carbonized discharges.