Modification of the divertor to a W-shaped pumped divertor and installation of pumping has enabled demonstration of the `puff and pump' effect in injected neon, albeit the pumping speed was modest (approximately 14 m3/s). It was demonstrated in ELMy H-mode plasmas with PNB≤25 MW that neon seeding and pumping was useful to control the radiation profiles 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 D2 puff, effectively improved the pumping efficiency of neon.
Itami, K., Hosogane, N., Konoshima, S., Sakurai, S., Asakura, N., Higashijima, S., … Shimada, M. (1999). Radiative plasma by impurity seeding in W-shaped pumped divertor experiment of JT-60U. Journal of Nuclear Materials, 266, 1097–1102. https://doi.org/10.1016/S0022-3115(98)00855-1