Characteristics of Exploding-Wire Plasmas

The phenomenon of exploding wire has been investigated in the energy range E < Ee to E > a few Ee, where Ee is the energy density required for complete evaporation of the wire. For E < Ee, macroscopic fragmentation (size ~ tens of micrometers) of wire takes place. As E is increased above Ee, the fragment size tends to atomic dimensions, and for E >> Ee explosive vaporization occurs resulting in high-temperature plasma. The study indicates that during the explosion, plasma is in a nonequilibrium state with temperatures as high as 10 eV or more. This plasma attains equilibrium in tens of nanoseconds. The free-expansion velocity of this plasma is of the order 105-106 cm/s and increases with increasing E. Consequently, the plasma density decreases for E >> Ee. After about 100 ns, the resulting plasma densities are in the region of 1018-1020 cm-3. Such plasmas have significant interest in the development of particle beams, laser, and fast switching systems.