(Ed) K.N. Wilson, T. Yamashina
Proceedings of Japan-U.S. Workshop P-196 on High Heat Flux Components and Plasma Surface Interactions for Next Devices
Date of publication:
proceedings, Japan-US, workshop, plasma surface interactions
The Japan-US Workshop P-196 was successfully carried out in Kyushu University. Chikushi Campus, from November 17 to 19, by the excellent organization due to Prof.Satoshi Itoh, Prof.N.Yoshida and Prof.T.Muroga. The agenda for very many presentations within 3 days period, was well organized by Prof.T.Hino. The last workshop held at Sandia National Laboratories in November of 1991 organized by Dr.W.Gauster, became a largest scale in the series of this workshop. The scale of the present workshop, again, became a largest one, e.g. 48 presentations and 66 participants. Of the 66 participants, 11 were from US, 1 from Canada, 6 from EC and 48 from Japan. The major concern was on the research and development required both for International Thermonuclear Experimental Reactor(lTER) and Large Helical Device(LHD). Most of the discussion items was similar to that of the last workshop, e.g. PFC and PSI in Large Device, High Heat Flux Component, Laboratory Studies and Neutron Damage. The presentation number concerning High Heat Flux Component was largest. In the session of PFC and PSI in Large Devices, the result of gas target divertor in DIIID, the prediction of tritium inventory in TFTR, JET divertor program, the status of LHD and the damage of B_4C coated tiles in JT-60U were presented. In addition, the impurity emission in TRIAM-1M was presented. The emphases were the reduction of heat flux, optimization of low Z materials such as boron and beryllium, tritium inventory/retention and control of recycling. In the field of HHF Component, introduced were the rapid progresses of brazing components in SNL, JAERI and NIFS. Now, the reliable HHF Component, which does not show significant damage after 1000 heat cycles with heat flux up to 20 MW/m^2, is available. The numerous developments for the HHF Component in the Japanese Industries were also introduced. In the Laboratory Studies, the major concerns were the recycling, the erosion both of low Z and high Z materials and the performance of boronization or boron doped material. It was indicated that emission of hydrogen atom from graphite becomes dominant when the temperature exceeds about 1000K. The relation of the hydrogen solubility with the degree of graphitization, which is useful for the evaluation of retention, was presented. It was also pointed out that the boron evaporation becomes serious when the temperature is over 1000 degree C. In the Tritium session, the retention properties of Be were newly introduced based upon numerous data and the experience in JET DT discharge. The attentions in use of tritium and the ion driven permeation in Mo were also discussed. For the graphites and the boron mixed graphites, the deteriorations of thermal conductivity due to neutron damage was also reviewed. The workshop of this series will be continued and be held in the next year, e.g. December 14-17, 1993, in UCLA. Finally we acknowlege the supports for the present workshop by the following Japanese industries; Hitachi, Hitachi Chemicals, JEOL, Kawasaki Heavy Industries, Marubun, Mitsubishi Atomic Power Industries, Mitsubishi Chemicals, Mitsubishi Heavy Industries, Toshiba Corp., Toyo Tanso.