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(EX/S1-1) Fast Dynamics of Type I ELM and Transport of ELM Pulse in JT-60U

N. Oyama1), Y. Miura1), A.V. Chankin1), N. Asakura1), K. Itami1), T. Oikawa1), H. Takenaga1), M. Sugihara1), Y. Kamada1), K. Shinohara1), JT-60 Team1)
1) Japan Atomic Energy Research Institute, Naka-machi, Japan

Abstract.  The mitigation of the large ELM heat load on the divertor target is one of the most important issues to be overcome on ITER. Since the ELM heat load strikes the divertor target not as a time-averaged load but as an instantaneous heat pulse, the evaluation of both ELM energy, and the time scale of the collapse and transport is very important. In JT-60U, the detailed dynamic behaviors of the collapse were measured using O-mode reflectometer. The duration of the collapse was within 0.35 ms and the lost pedestal density was recovered quickly within 0.5 ms. The collapse reached 10 cm inside the separatrix, which corresponds to twice the pedestal width of 5 cm. Dedicated edge density measurements on high- and low-field side revealed the poloidal asymmetry of the collapse of density pedestal for the first time. The measurement of SOL flow and heat load to the divertor target by using SOL Mach probe and IRTV showed that convective transport of the SOL plasma gave large contribution to the ELM heat deposition process.

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IAEA 2003