Abstract:
Numerical solutions of the hydrodynamic equations of motion for a collapsing bubble have shown that shock waves can be generated during the collapse. It has been shown that these shock waves can supply and remove energy from the center of the bubble rapidly enough to account for the picosecond duration flashes that are observed experimentally. However, these solutions have not included energy loss mechanisms, so the calculated temperatures are excessively high. More accurate numerical simulations are discussed that (i) model the shocked gas as a plasma with distinct ion, electron, and radiation temperatures, and (ii) include energy losses by ion conduction, electron conduction, and radiant energy transport. As an example, a sonoluminescing bubble of deuterium is considered, whose sinusoidal driving amplitude is enhanced by a small pressure spike. Although the calculated radiation and electron temperatures are only tens of eV, the calculated peak ion temperatures are a couple hundred eV ((approximately equal to)2 000 000 K), which may be sufficient to initiate a very small number of thermonuclear reactions at the center of the bubble. [Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.]