Localized-impact damage caused by proton bombarding in mercury target

Futakawa, Masatoshi  ; Kogawa, Hiroyuki  ; Ishikura, Shuichi*; Kudo, Hisaaki*; Soyama, Hitoshi*

A liquid-mercury target system for the MW-scale target is being developed in the world. The moment the proton beams bombard the target, pressure waves will be generated in the mercury by the thermally shocked heat deposition. Provided that the negative pressure generates through its propagation in the mercury target and causes cavitation in the mercury, there is the possibility for the cavitation bubbles collapse to form pits on the interface between the mercury and the target vessel wall. In order to estimate the cavitation erosion damage, Split Hopkinson Pressure Bar (SHPB) tests impact tests were performed to impose the impact pressure to the interface between mercury and solid metals. In particular, the surface hardening treated samples: Kolsterising, some coatings are investigated. As results, it is confirmed that the pitting damage is suppressed by surface hardening treatments and relative hardness appeared to be a good correlating parameter on impact erosion resistance.