The current density and the specific energy input in fast electrical explosion

The electrical explosion of wires is considered as a method for studying the behavior of materials under the conditions of fast heating. A fast electrical explosion occurs subject to the conditions that the heating time is shorter than the time required for capillary and magnetohydrodynamic instabilities to develop and that this time is longer than the time required for the current to expand throughout the wire cross section. Corresponding similarity criteria have been derived for each of the processes disturbing the uniform heating of a wire. The conditions for fast electrical explosion have been experimentally realized. The current density was varied from 10/sup 7/-10/sup 9/ A/cm/sup 2/ resulting in heating rates between 10/sup 10/ and 10/sup 13/ J/(g.s). Exploded wires of copper, nickel, tungsten, and molybdenum were investigated. These experiments have shown that the energy density introduced into the wire material depends on the heating rate (i.e., the current density). Fourfold overheating of the materials in the condensed state has been attained. It has been found that the specific current action also increases with increasing current density but to a lesser degree than the energy input.