2019 Volume 4 Pages 33-37
A liquid mercury target for the pulsed spallation neutron source has been in operation in the Japan Proton Accelerator Research Complex (J-PARC). Liquid mercury enclosure vessel made of stainless steel is damaged by the cavitation erosion induced by pressure waves that are generated by proton beam injection. A double-walled structure with a narrow channel in front of the mercury target vessel was adopted to the vessel for expecting to mitigate cavitation damage. In this study, we at first made clear of the mechanism of cavitation damage mitigation in narrow channel through visualizing the growing and collapsing behaviors of the spark-induced cavitation bubbles under flow field using a high-speed video camera. Furthermore, we measured the wall vibration due to the cavitation bubble collapse with parametrically changing flow velocity. While the microjet without flow collides perpendicularly with the wall, the microjet with flow collides with an inclined angle from the perpendicular. As the results, the collision pressure was found to be mitigated by flowing effect.
