Parallel and drift plasma flows in SOL, and influence on impurity transport in JT-60U Tokamak

Asakura, Nobuyuki; Shimizu, Katsuhiro; Nakano, Tomohide; Higashijima, Satoru; Kubo, Hirotaka; Takenaga, Hidenobu

The measurements of the parallel SOL flow (Mach number, M) and electric field (Er) both at the high-field-side (HFS) and low-field-side (LFS) have been accomplished using Mach probes in JT-60U. Particle fluxes towards the HFS and LFS divertors produced by the parallel SOL flow (niMCs) and ErxB drift flow (niEr/B) were evaluated. For the case of intense gas puffing from the plasma top (puff and pump), Zeff was reduced largely to 1.3, comparing to 1.42 for the divertor gas puff. It was found that both M and ni in niMCs were enhanced, in particular, at HFS. On the other hand, niEr/B for the two cases were comparable since ni increased and Er decreased for the puff and pump. Friction force and thermal force on impurity ions were estimated from the measured M, ne, Te and Ti, and ratios of Ffric/Fi-therm at HFS increased to 3-4 compared to 1.5-1.8 for the divertor gas puff. This result was consistent with a conventional model of reduction in Zeff. Two-dimensional transport of the carbon impurity at the HFS and LFS divertors was discussed using IMPMC (Impurity Monte-Carlo) code.