OBSERVATIONS OF A CAVITATION BUBBLE INTERACTING WITH A SOLID BOUNDARYAS SEEN FROM BELOW

We present a schlieren photographic sequence of a laser generated cavi ty in water interacting with a solid boundary as seen from the boundar y's perspective looking through the bubble. Previous studies have phot ographed the collapsing bubble from the side and it is unclear from th ese photographs once a bubble becomes toroidal how the central hole de velops. Our schlieren sequence displays the jet first penetrating the lower bubble surface and then follows the evolution of the central cha nnel as the bubble contracts and reexpands. It is felt that the bubble shapes recorded add further knowledge to the possible damage mechanis ms of cavitation. (C) 1996 American Institute of Physics.