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Shu, Wataru; Kawakubo, Yukio*; Luo, G.; Nishi, Masataka
Journal of Nuclear Science and Technology, 40(12), p.1019 - 1026, 2003/12
Times Cited Count：4 Percentile：31.64(Nuclear Science & Technology)Recovery of tritium from co-deposited layers is a crucial issue for fusion machines that use carbon as plasma facing materials. In this study, the removal rate of the JT-60 and TFTR co-deposited layers by KrF laser was measured for varying laser energy density. The removal rate of 5.0 
m/pulse was achieved for the JT-60 co-deposited layers at the energy density of 11 J/cm
for KrF excimer laser. Hydrogen (tritium) was released in the form of hydrogen molecules and readily recovered. The formation of cones due to local surface melting was observed at the KrF laser energy density of 0.8 J/cm, whereas strong melting was determined to be the mechanism of the ablative removal of the JT-60 co-deposited layers at the energy density greater than the ablation threshold.
Shu, Wataru; Kawakubo, Yukio*; Nishi, Masataka
Applied Physics A, 76(3), p.421 - 425, 2003/03
Times Cited Count：16 Percentile：53.97(Materials Science, Multidisciplinary)Recovery of tritium from co-deposited layers formed in TFTR deuterium-tritium plasma operations was investigated by the use of an ArF excimer laser operating at the wavelength of 193 nm. At the laser energy density of 0.1 J/cm, a transient spike of tritium release rate was observed at initial irradiation. Hydrogen isotopes were released in the forms of hydrogen isotope molecules during the laser irradiation in vacuum, suggesting tritium can be recovered readily from the released gases. In a second experiment, hydrogen (tritium) recovery from the co-deposited layers on JT-60 tiles was investigated by laser ablation with focused beam of the excimer laser. The removal rate of the co-deposited layers was low when the laser energy density was smaller than the ablation threshold (1.0 J/cm), but reached to 1.1 m/pulse at the laser energy density of 7.6 J/cm. The temperature on the surface during the irradiation was measured on the basis of Planck's law of radiation, and the maximum temperature at the laser energy density of 0.5 J/cm decreased from 3570 K at the initial irradiation to 2550 K at 1000th pulse of the irradiation.
Shu, Wataru; Kawakubo, Yukio*; Masaki, Kei; Nishi, Masataka
Journal of Nuclear Materials, 313-316(1-3), p.584 - 587, 2003/03
Times Cited Count：22 Percentile：79.74(Materials Science, Multidisciplinary)no abstracts in English
Shu, Wataru; Gentile, C. A.*; Skinner, C. H.*; Langish, S.*; Nishi, Masataka
Fusion Engineering and Design, 61-62, p.599 - 604, 2002/11
Times Cited Count：13 Percentile：63.36(Nuclear Science & Technology)no abstracts in English
Oya, Yasuhisa; Tadokoro, Takahiro*; Shu, Wataru; Hayashi, Takumi; Ohira, Shigeru; Nishi, Masataka
Journal of Nuclear Science and Technology, 38(11), p.967 - 970, 2001/11
Times Cited Count：6 Percentile：44.09(Nuclear Science & Technology)no abstracts in English
Oya, Yasuhisa; Shu, Wataru; Ohira, Shigeru; Hayashi, Takumi; Nakamura, Hirofumi; Sakai, T.*; Tadokoro, Takahiro*; Kobayashi, Kazuhiro; Suzuki, Takumi; Nishi, Masataka
Journal of Nuclear Materials, 290-293, p.469 - 472, 2001/03
Times Cited Count：6 Percentile：44.09(Materials Science, Multidisciplinary)no abstracts in English
