Measurement of cavitation in a downstream conduit of the liquid lithium target for international fusion materials irradiation facility

Kondo, Hiroo; Kanemura, Takuji; Furukawa, Tomohiro  ; Hirakawa, Yasushi ; Wakai, Eiichi  

A liquid-Li free-surface stream is to serve as a beam target (Li target) for the IFMIF. As a major activity for the Li target in the IFMIF/EVEDA, the EVEDA Li test loop (ELTL) was constructed. This study focuses on cavitation-like acoustic noise in a conduit downstream of the Li target. This noise was detected by using acoustic-emission sensors. The intensity of the noise was examined versus cavitation number of the Li target. In addition, a time-frequency analysis for the acoustic signal was performed to characterize the noise. The results are as follows: (1) the intensity of the noise was increased as decreasing the cavitation number; (2) the noise was at first intermittent in a larger cavitation number, subsequently the noise became continuous as decreasing the cavitation number; (3) the noise consisted of a number of a high frequency acoustic emission which occurred in a short duration. For these results, we conclude that cavitation occurred in the downstream conduit.