Experimental investigation of transient pressure waves produced in dielectric liquids

The experimental results reported in this paper mainly concern the two first transient pressure waves emitted after a fast (similar to ns) and localized (similar to mu m) injection of electrical energy W-i in insulating liquids. The influence of various parameters (hydrostatic pressure P-infinity, injected energy W-i, etc.) on the relative amplitude of these two transient pressure waves are presented and discussed. The analysis shows clearly a difference of behavior, in particular their dependence as a function of hydrostatic pressure, between these two waves. Basically, the physical processes leading to their emission are quite different. The first pressure transient is a consequence of the plasma relaxation, whereas the second one is due to the bubble collapse. According to these results, the chronology of the events is more improved, as well as the theoretical analysis. (C) 2000 Acoustical Society of America. [S0001-4966(99)01512-X].