Dynamics of heterogeneous liners with prolonged plasma creation

Prolonged plasma creation in heterogeneous liners, in which the liner subst ance is separated into two phase states (a hot plasma and a cold skeleton), is investigated both experimentally and theoretically. This situation is t ypical of multiwire, foam, and even gas liners in high-current high-voltage facilities. The main mechanisms governing the rate at which the plasma is created are investigated, and the simplest estimates of the creation rate a rt: presented. It is found that, during prolonged plasma creation, the elec tric current flows through the entire cross section of the produced plasma shell, whose thickness is comparable with the liner radius; in other words, a current skin layer does not form. During compression, such a shell is fa irly stable because of its relatively high resilience. It is shown that, un der certain conditions, even a thick plasma shell can be highly compressed toward the discharge axis. A simplified numerical simulation of the compres sion of a plasma shell in a liner with prolonged plasma creation is employe d in order to determine the conditions for achieving regimes of fairly comp act and relatively stable radial compression of the shell. (C) 2001 MAIK "N auka/Interperiodica".