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Abstract: Erosion/deposition distribution and hydrogen isotope behavior in the JT-60U plasma-facing wall were investigated. Distribution of the tritium, which was produced by D–D nuclear reaction, was not correlated with erosion/deposition distribution. The tritium distribution can be explained by the distribution of high-energy tritium ion-implantation due to ripple loss. Deuterium distribution in the divertor region was different from the tritium distribution and not well correlated with the deposition. The highest D/C was ∼0.05 at the bottom of the outer dome wing, which is much less than that observed in other tokamaks. For the deuterium retention, at least two retention processes (ion-implantation and co-deposition) were found on the dome region. The systematic dust collection gave the small amount of dust (∼7g: 0.2mg/s production) in the whole vessel of JT-60U. Deposition was observed at the remote area of the outer divertor region. [Copyright &y& Elsevier]

Abstract: We have investigated hydrogen isotopes retention in graphite tiles used as outboard first wall armors of JT-60U by means of SEM, TDS and SIMS. The SEM examination confirmed that these tiles are mostly eroded. Different from graphite divertor tiles, in which H retention was dominant owing to isotopic replacement during HH discharges preformed after DD discharges to remove tritium, deuterium is dominated in hydrogen isotopes retention of the outboard first wall tiles showing deeper penetration. This is attributed to the injection of high energy D and less isotopic replacement due to the lower temperature of the outboard first wall tiles. This type of hydrogen retention could not be avoided for the metallic wall. Although the amount of hydrogen isotopes retained per unit area in the outboard first wall tiles was much less than that for the divertor tiles, the integrated retention over the whole first wall surface could be very large. [Copyright &y& Elsevier]

Abstract: Retention and depth profile of all hydrogen isotopes (hydrogen, deuterium and tritium) in the carbon tiles of outer divertor, outboard baffle plate and outboard first wall in JT-60U, which were mostly eroded, were measured by TDS, SIMS and TIPT, and discussed from view points of tile temperature, incident energy and flux of impinging H, D and T. The distribution of T in the analyzed tiles was compared with the impinging flux of tritium produced by DD reactions, which was calculated by the OFMC code. In this paper, H, D and T retention mechanisms and isotopic replacement effects are summarized. [Copyright &y& Elsevier]