Spatial and temporal distributions in exploding-wire plasmas

The effect of small energy pulses (τ∼0.1–10 ns) in exploding-wire plasmas has been analytically investigated in this study. It is shown that the deposited energy distribution is an increasing function of the radial distance in wire. The energy distribution is more pronounced with smaller τ and becomes uniform for τ>10 ns for given wire radius ∼12.5 μm. The resulting fragments exhibit a distribution in sizes and are smaller towards the wire surface due to a higher energy density (E) than around the axis. For E∼Ee (the energy density needed for total evaporation), the fragment sizes range from μm to nm from axis towards surface, respectively. Subsequent to explosion, for E≥Ee, there are distributions in plasma temperature (Tp) and plasma density (Np) as well. Typically for E∼10 kJ/g in copper, Tp is more than a few percent higher at the leading end than in the trailing end. As compared to this, E≫Ee gives a uniform plasma with uniform Tp irrespective of τ. Consequently, uniform plasma can be obtained either with very large E, or in case of small E with large τ.