Abstract (Invited)

Dynamics of Collapsing Bubbles: Sonoluminescence and Bubble Fusion

R.Nigmatulin, I.S.Akhatov, A.S.Topolnikov, R.K.Bolotnova (Institute of Mechanics, Ufa Branch of the Russian Academy of Sciences, Ufa, Russia); R.T.Lahey, Jr. (Rensselaer Polytechnic Institute, Troy, NY, USA); R.P.Taleyarkhan (Oak Ridge National Laboratory, Oak Ridge, TN, USA.)

e-mail: iskander@anrb.ru

When ultrasonically forced oscillating cavitation bubbles implode they can strongly compress the entrapped vapor/gas such that the temperature may become so large that plasma is formed and a visible light pulse is emitted. Recent experiments have allowed detailed studies of the dynamics of acoustically levitated sonoluminescent bubbles [Gaitan et al., 1992]. In particular, there have been important findings concerning the stability of bubble size, shape and position, the effect of liquid temperature, noble gas doping etc. [Barber et al., 1997]. All these effects can be understood in the framework of a theoretical model of bubble dynamics which accounts for liquid and gas compressibility, surface tension, gas diffusion, and kinetics of evaporation/condensation process [Nigmatulin et al., 1996; 2000]. This model has been developed and tested to calculate the dynamics of laser-induced cavitation bubbles [Akhatov et al., 2001]. These calculations show good agreement with experimental data. If bubble collapse is rapid enough shock waves are formed and the heating can be quite strong, resulting in very high temperatures near the center of the bubble. Indeed, it is reasonably easy to achieve gas/plasma temperatures comparable to those on the surface of the sun. However, it is possible to achieve much higher temperatures that thermonuclear fusion may occur. Recently a major breakthrough was made in which cavitation bubbles were forced to compress so strongly that thermonuclear fusion occurred [Taleyarkhan et al., 2002]. Such a bubble fusion is predicted by advanced mathematical model and code that include the Mie-Gruniesen equation of state, the dissociation and ionization processes and nuclear fusion kinetics.

Section : 4