ENHANCED THERMAL DISSIPATION AND THE RAYLEIGH-TAYLOR INSTABILITY IN EMULSION-LIKE MEDIA

Rayleigh-Taylor instability in a finely structured emulsion-like mediu m consisting of the two components of different compressibility is con sidered. Although the term ''emulsion'' is used to describe the struct ure of the medium, under typical conditions of pulsed fusion devices t he medium is actually a plasma. The two components are chosen in such a way that their densities in the unperturbed state are approximately equal. Specific emphasis has been made on the analysis of perturbation s with the scale <(lambda)over bar> considerably exceeding the size of the grains alpha. Average equations describing such perturbations are derived. The difference in compressibility of the two components lead s to the formation of temperature variations at the scale alpha, and i ncreases the rate of the thermal dissipation by a factor (<(lambda)ove r bar>/alpha)(2). The strongest stabilizing effect of the thermal diss ipation takes place when the heat conduction time is comparable with t he instability growth rate. (C) 1998 American Institute of Physics.