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Tajima, Satoshi; ; Mizuhashi, Kiyoshi; Saito, Yuichi; Uno, Sadanori; ; Ishii, Yasuyuki; Sasuga, Tsuneo; Tanaka, Shunichi
Dai-6-Kai Tandemu Kasokuki Oyobi Sono Shuhen Gijutsu No Kenkyukai Hokokushu, p.14 - 17, 1993/00
no abstracts in English
Hirano, Koichiro; Fukuda, Makoto*; Ezato, Koichiro*; Tokunaga, Kazutoshi*
no journal, ,
The beam targets of the J-PARC linac are multiply irradiated by hydrogen negative ion beams with beam energy of 3 MeV. The purpose of this study is to clarify the pulsed heat load conditions that can withstand multiple irradiations when beam targets made of tungsten materials are used. Using an off-line beam test-stand with a 3 MeV hydrogen negative ion beam, multiple irradiation tests were conducted on tungsten materials for ITER, in which temperature changes of heating (3200 degree) and cooling (160 degree) were repeatedly given at a period of 5 Hz. This paper reports on the surface observation of the tungsten materials and the partial pressure measurements by a quadrupole mass spectrometer.
Fukuda, Makoto*; Tokunaga, Kazutoshi*; Ezato, Koichiro*; Hirano, Koichiro
no journal, ,
Tungsten which is used as a plasma-facing material of the ITER divertor, is expected to receive various type of heat load during ITER operation. Therefore, it is necessary to understand the surface damage of tungsten under various heat load conditions. In this study, as part of the investigation of the effects of short-pulse repetitive heat loads on tungsten, the effects of multiple irradiations of the negative hydrogen ion beam (3 MeV, 5 Hz) on the surface of tungsten were investigated. As a result of the investigation, it was clarified that microcracks were formed on the surface of tungsten exposed to multiple irradiations, and that the microstructure was also changed.
Tokunaga, Kazutoshi*; Nomiyama, Yukino*; Fukuda, Makoto*; Ezato, Koichiro*; Hirano, Koichiro
no journal, ,
It is known that the surface temperature of tungsten (W) divertor during the slow transient at steady state plasma operation in ITER will be higher than that of the recrystallization temperature. Therefore, thermal behavior of recrystallized W(RC-W) exposed the expecting heat loadings during ITER plasma operation is necessary to be investigated. In the present work, RC-W has been exposed to multiple irradiation of negative hydrogen ion beam (3 MeV, 5 Hz) and the effect of repeated short pulse heat loading on surface modification has been investigated. The results have also compared with that of stress-relieved W (SR-W). The area of surface modification of RC-W is larger than that of SR-W in the case of a peak temperature of 1650 degree. The circular cracks along grain boundaries are formed and complex surface modification including line like uneven surface are seen. These modifications of RC-W are different from that of SR-W.