Volume recombination and detachment in JET divertor plasmas

摘要

The spatial distribution of recombination has been studied in the detaching phases of L and H-mode discharges. Recombination is detected by the sudden increase in intensity of the high quantum number states of the Balmer series of hydrogen. In L-mode, detachment occurs completely and the radiation moves to a region near the X-point. In H-mode, detachment only occurs between ELMs. There is a marked decrease in the pedestal T_e inside the separatrix and loss of confinement before detachment takes place.