Mockup test of the J-PARC mercury target for microbubble injection, 2; Mockup test apparatus and pressure drop characteristics

Kinoshita, Hidetaka; Kogawa, Hiroyuki; Haga, Katsuhiro; Naoe, Takashi  ; Ida, Masato; Futakawa, Masatoshi

Mercury is used for the spallation neutron source target of the J-PARC Materials and Life Science Experimental Facility (MLF). Pressure is generated by pulsed proton beam because of high heat generation within very short time. Cavitation erosion is occurred at target vessel inner surface by pressure wave. This phenomenon will be shortening the life time of the target vessel. Pressure wave mitigation by microbubble injection will be effective to solve this issue. The bubble size and void fraction are confirmed by numerical analysis for pressure wave mitigation. But the information of effective microbubble injection system and microbubble motion in flowing fluid is not sufficient. Then R&D of microbubble injection system and bubble observation were conducted experimentally. In this report, introduction of the mockup test apparatus simulated actual target and test results of pressure drop at microbubble injection system are presented.