Speaker
Hiroo Kondo
(Japan Atomic Energy Agency)
Description
A liquid-Li free-surface stream flowing at 15 m/s under a high vacuum of 1E−3 Pa is to serve as a beam target (Li target) for the planned International Fusion Materials Irradiation Facility (IFMIF). The Engineering Validation and Engineering Design Activities (EVEDA) for the IFMIF are implemented under the Broader Approach. As a major activity of the Li target facility, the EVEDA Li test loop (ELTL) was constructed by the Japan Atomic Energy Agency. In a validation experiment using the ELTL, the stable Li target under IFMIF conditions (Li temperature: 250 deg.-C, velocity: 15 m/s, vacuum pressure: 1E−3 Pa) has been demonstrated so far.
This study focuses on cavitation-like acoustic noise which was detected in a conduit upstream of the Li target. This noise was detected by using acoustic-emission sensors (AE-900S-WB, NF Corp.) that were installed at several locations upstream and downstream of the target assembly via acoustic wave guides (stainless steel rods). The intensity of the acoustic noise was measured versus flow rate of the Li target in several gaseous pressure cases. A time-frequency analysis by Continuous Wavelet Transform (CWT) for the acoustic signal was performed to characterize the acoustic noise, which determined the cause of the acoustic signal was cavitation. In addition, the occurrence of cavitation at the highest point of the pipe upstream of the target assembly was theoretically discussed by using Bernoulli’s equation and compared with the experimental observations. As a result, we revealed a proper start-up pressure of the Li target to avoid cavitation upstream of the target assembly, which will be a design basis for the future IFMIF.
Co-authors
Eiichi Wakai
(Japan Atomic Energy Agency, Ibaraki, Japan)
Hiroo Kondo
(Japan Atomic Energy Agency, Ibaraki, Japan)
Takuji Kanemura
(Japan Atomic Energy Agency, Ibaraki, Japan)
Tomohiro Furukawa
(Japan Atomic Energy Agency, Ibaraki, Japan)
Yasushi Hirakawa
(Japan Atomic Energy Agency, Ibaraki, Japan)
