M. Nishikawa

Y. Hirooka

Y. Ohgaki

Y. Ohtsuka

National Institute for Fusion Science (NIFS-Repository)

§ 19. A New Facility for Proof-of-PrincipleExperiments on Innovative PFC Conceptsand the First Experiments on Liquid Gaand LiHirooka, Y. (NIFS)Ohgaki, Y., Ohtsuka, Y., Nishikawa, M. (Osaka Univ.)Over the past several years, much has beendiscussed about the need for the development ofinnovative plasma-facing component (PFC)concepts for steady state fusion power reactors tocome after ITER. These innovative concepts areintended to resolve technical issues, including (1)materials erosion lifetime; (2) tritium build-upalong with codeposition of eroded materials; (3)high heat flux removal; and (4) fuel and impurityparticles control.Among these PFC concepts, the mostpromising is the Moving-Surface Plasma FacingComponent (MS-PFC) concept: the plasma-facingsurface, either made of solid or liquid, will becirculated. In this concept, one expects thaterosion will no longer limit the lifetime of PFCs.Also, tritium recovery can be done ex-situ. Heatremoval can also be done without complex heatsink structures. Finally, this concept willregenerate the surface particle trappingcapabilities automatically. In theory, theMS-PFC can resolve all the existing PFC issues.Out of these outstanding issues we have firstchosen to demonstrate the particle controlcapability of the MS-PFC concept. In most ofthe existing confinement experiments, particlecontrol has been done, using wall conditioningtechniques, e.g., boronization. However, it is wellknown that these techniques are not quite suitablefor steady state reactors because the wall surfacewill be saturated. with trapped particles, whichthen require re-conditioning.In our recent experiments, it has beensuccessfully demonstrated that reduced (5-10%)hydrogen recycling can be maintained even atsteady state, using a laboratory scale experimentalsetup that employs a rotating drum bombardedwith steady state plasmas in the NAGDIS-Ifacility at Nagoya Univ. [1,2].As the next step, innovated PFC conceptsusing liquid metals and molten salts should beevaluated. However, it is of tremendousdifficulty to build a liquid metal circulating systemin a small laboratory scale. Also, thetemperature control, i.e. vapor pressure control, isthe key to these experiments. Therefore, wehave chosen to construct a new facility to enableto expose standing liquid metals in a crucible tovertically incoming plasmas as the first-phaseexperiment. However, in the second phase, oneneeds to simulate a "liquid waterfall" bombardedwith horizontally incoming plasmas.In order to conduct these two phases ofexperiments in one single test stand. A newfacility, shown in Fig. 1, has been constructed as ajoint project by NIFS and Osaka Univ. The firstliquid Ga and Li experiments have been conductedand the results have been presented at the recentUS-Japan workshop held in Seattle for the periodof Jul. 28-30th, 2003.Vertical configuration- .....---¥IasmasourceHorizontal configurationFig.l A schematic diagram of the innovative PFCconcept test facility [2].References[1] Y Hirooka et al., Fusion Eng. & Des.65(2003)413-421.[2] Y. Hirooka, et al., presented at ANS-TOFE,Washington DC, 2002.387

A New Facility for Proof-of-Principle Experiments on Innovative PFC Concepts and the First Experiments on Liquid Ga and Li

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