Radiative plasma by impurity seeding in W-shaped pumped divertor experiment of JT-60U

Modification of the divertor to a W-shaped pumped divertor and installation of pumping has enabled demonstration of the 'puff and pump' effect in inje cted neon, albeit the pumping speed was modest (similar to 14 m(3)/s). It w as demonstrated in ELMy H-mode plasmas with P-NB less than or equal to 25 M W that neon seeding and pumping was useful to control the radiation profile s in the main and divertor plasmas, while the large radiation loss from the divertor MARFE was sustained. It was suggested that the neon enrichment in the divertor plasma, which was enhanced by the main D-2 puff, effectively improved the pumping efficiency of neon. (C) 1999 Elsevier Science B.V. All rights reserved.