JT-60UにおけるW型ダイバータタイル中の軽水素および重水素蓄積挙動と損耗・再堆積分布

概要

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Distributions and retentions of hydrogen and deuterium retained in graphite tiles placed in the W-type divertor of JT-60U were studied by secondary ion mass spectroscopy and thermal desorption spectroscopy, respectively. Poloidal profiles of hydrogen and deuterium retention were compared to those of the erosion/deposition thicknesses observed by a scanning electron microscope and/or micro meter. It was found that the large amount of hydrogen isotopes was retained in the redeposited layers appeared at the inner divertor and the outer wing area. Most of hydrogen isotopes were retained uniformly in the re-deposition layers with the hydrogen isotope concentration of 0.02-0.03 in (H+D)/C atomic ratio, which is much lower than that with saturation concentration of 0.4-1 in other tokamaks operated below 500 K. Because the operation temperature of JT-60U was kept to be above 573 K and the surface temperature of the divertor tiles were likely heated up above 800 K during a discharge. Only small amount of hydrogen was retained in the eroded area appeared at the outer divertor and the inner wing area. In all cases, the top most surface layers were dominated by hydrogen indicating easy replacement of deuterium and saturation of hydrogen isotope concentration during the discharge.
社団法人プラズマ・核融合学会の論文
2006-04-25