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Haga, Katsuhiro; Kogawa, Hiroyuki; Wakui, Takashi; Naoe, Takashi; Futakawa, Masatoshi
Proceedings of 20th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-20) (USB Flash Drive), 6 Pages, 2012/03
Cavitation damage caused by the pressure wave in mercury is the crucial issue for the high power mercury target. Microbubble injection into mercury is the technology to mitigate the pressure wave, and the techniques to generate microbubbles in mercury flow, and to achieve the proper distribution of microbubbles have been investigated. We developed the swirl type bubbler which can generate the microbubbles efficiently. We performed mercury flow experiments using the target mockup model. We found that the proper size of microbubbles were distributed in the target, but the void fraction was less than 10
at the bottom area, which was lower than an expected value. In order to increase the void fraction, we changed the design of the mercury flow channel, moving the bubbler position forward near the beam window. With the help of the swirl flow, the homogeneity of microbubbles distribution at the beam window will be improved and the void fraction at the bottom area will be increased.
Sakai, Kenji; Futakawa, Masatoshi; Takada, Hiroshi; Sakamoto, Shinichi; Maekawa, Fujio; Kinoshita, Hidetaka; Seki, Masakazu; Haga, Katsuhiro; Kogawa, Hiroyuki; Wakui, Takashi; et al.
Proceedings of 20th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-20) (USB Flash Drive), 6 Pages, 2012/03
This report investigates behaviors and damages of each component in a neutron target station of the MLF at the J-PARC at the time of the Great East Japan Earthquake (GEJE). At the date of the GEJE, in the MLF, strong quakes were detected at several instruments, an external power supply were lost, all of the circulation systems were shut down automatically, and a hydrogen gas was released as planned. Leakage of activation liquids and gases did not occur. While, the quakes made gaps between shield blocks and ruptured external pipe lines for air and water by subsidence. But significant damages on the components of the target station were not found though a loss of compressed air supply affected lock systems with air cylinders and pneumatic operation values. These results substantiated a validity of safety design on the target station for emergency accidents.
Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya; Nakamura, Mitsutaka; Kajimoto, Ryoichi*; Inamura, Yasuhiro; Takahashi, Nobuaki; Aizawa, Kazuya; Suzuya, Kentaro; Shibata, Kaoru*; et al.
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AMATERAS is a disk-chopper-type spectrometer installed at beam-line No. 14 at Materials and Life Science Experimental Facility (MLF) of J-PARC. AMATERAS is equipped with an extra chopper for pulse shaping at the upstream position, in addition to a monochromating chopper. Owing to the use of these choppers and the high peak intensity from a coupled moderator source at MLF, AMATERAS is designed to realize high-intensity and fine and flexible energy resolution measurements in quasielastic and inelastic neutron scattering experiments in cold and sub-thermal neutron energy region. The spectrometer had the first neutron beam in May 2009 and user program started from December, 2009. During the course of commissioning and users' experiments, the performance of the spectrometer was confirmed by conducting test experiments. In this presentation, we will show the current status of AMATEAS including the results of performance tests and some of examples of scientific outputs.