Impurity reduction during 'puff and pump' experiments on DIII-D

Results are presented from an experiment in which a large amount of deuterium gas was continuously puffed at the scrape-off layer and exhausted from the DIII-D pump divertor ('puff and pump' technique). The experiments were conducted with a single null divertor configuration during edge localized mode (ELM)ing H mode. Steady state density conditions were attained during the strong deuterium puff. The deuterium puff reduced the central plasma density of argon, puffed continuously as a trace impurity, by as much as a factor of 20, and the central argon radiated power density by as much as a factor of 10.