Fmj. Mccluskey et A. Denat, THE BEHAVIOR OF SMALL BUBBLES GENERATED BY ELECTRICAL-CURRENT IMPULSES OVER A WIDE-RANGE OF APPLIED PRESSURES, Journal of applied physics, 80(4), 1996, pp. 2049-2059
Very small bubbles are generated in chemically different insulating li
quids in a repeatable and controlled way. A constant de voltage is app
lied between a sharp point and a plane electrode. Above a threshold vo
ltage, the current is ''impulsional.'' The origin of each impulse is a
n electron avalanche while the consequence is the formation of a small
bubble at the point electrode. The relationship between the injected
electrical energy and the maximum bubble size is examined. Depending o
n the liquid used, and therefore the level of energy injected, differe
nt behaviors were observed. In particular, results for very low energy
injections were explained by mechanical rather than thermal processes
. The nonequilibrium plasma formed following an electron avalanche, br
ings about the emission of a pressure transient, behind which there is
an ''afterflow'' of matter. The liquid travelling outwards from this
point source causes the liquid to break down mechanically, thus formin
g an almost empty cavity, which disappears on collapse. In the case of
high energy injection, energy is lost to local heating of the liquid.
(C) 1996 American Institute of Physics.