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Nakano, Tomohide; Asakura, Nobuyuki; Shimizu, Katsuhiro; Konoshima, Shigeru; Fujimoto, Kayoko; Kawashima, Hisato; Higashijima, Satoru
no journal, ,
WeThe intensity ratios of 9 C IV lines from the C IV emission peak were analyzed with a collisional-radiative model. From the analysis, it was found that the lowly-excited levels (
) were predominantly populated by the excitation from the ground state of 
by an electron impact with an electron temperature of 10 eV and an electron density of 
, while the highly-excited levels (
) by the volume recombination of 
and an electron with an electron temperature of 3 eV. With these parameters and the absolute intensity of C IV (
) and C IV (
) lines, the radiation power due to the excitation and the recombination process were determined to be, respectively, 40% and 0.5% of the total radiation power measured by a bolometer. Further, it was found that the recombination flux was comparable to the 
ionization flux.
Asakura, Nobuyuki; Nakano, Tomohide; Kawashima, Hisato; Masaki, Kei; Fujimoto, Kayoko; Ono, Noriyasu*; Tanabe, Tetsuo*
no journal, ,
ELMy H-mode plasmas have been recently operated during long duration under the wall saturated condition in JT-60U. Investigation of the heat and particle handling and PSI studies such as erosion and deposition of carbon have been progressed. Deuterium gas balance has been studied in short term, and it was found that globally saturated condition of PFCs is caused mostly by an increase in wall temperature near the divertor. Increase in the divertor pumping was investigated to demonstrate particle control under the globally saturated condition. Erosion and deposition of the carbon target has been analyzed at the divertor tiles after the experiment campaigns. Deposition pattern and its rate on the tile surface were similar to those at other tokamaks such as JET. On the other hand, deposition depth of the tile edge was relatively smaller, which suggests difference of tile arrangement. Deuterium co-deposition was found to be smaller. Influence of operation temperature is discussed.
Oya, Kaoru*; Tanabe, Tetsuo*; Takenaga, Hidenobu; Inai, Kensuke*
no journal, ,
Dynamic simulation results of erosion and redeposition on plasma facing materials were reported. In JT-60U W-shaped divertor, erosion was dominant on the outer divertor plate, whereas deposition was dominant on the inner plate. The erosion and redeposition patterns on the plates were calculated using the EDDY code, which treats transport of impurities released from the plates in the plasma and dynamic material mixing processes. Forthermore, energy-dependent reflection and dissociation of hydrocarbons on the surface was employed in addition to a constant sticking coefficient on the plate. Hydrocarbons released from the outer divertor plate were immediately ionized when entering the plasma and were redeposited near the release position. But they were subjected to re-erosion, resulting in small effective sticking. On the whole, most area of the outer divetor plate was eroded. In contrast, the inner divertor plate was dominated by deposition due to lower plasma temperature. These results agreed with the experimental observations. Simulations for the twin test limiter experiments in TEXTOR, hydrocarbon redeposition in castellated surfaces and molecular dynamics of ion-solid interactions were also reported.