Different Mechanisms of Shock Wave Generation and Breakdown Upon Electrical Explosion of Thin Wires in Open Air

Summary form only given. Experimental data on the electrical explosion of micron-scale diameter wires with a 10 kA current pulse having a rise rate of up to 50 A/ns are presented. Numerous experiments have made it possible to systemize data on the explosion of copper and tungsten wires in open air. A series of optical images of discharge channels enabled us to form a picture of the motion of explosion-generated shock wave (SW) fronts and the boundaries of dense vapor from the electrical explosion of the wires (EEW). This served as the base for constructing a simple model of processes accompanying the generation of a shock wave from the EEW in air. It can also be stated that when wires are electrically exploded in air, a breakdown of the inter-electrode gap is possible in two scenarios, depending to a large extent on the thermophysical properties of the exploding wires. In the first case, the breakdown occurs in the air at the boundary of dense explosion products, e.g., tungsten vapor. The shunting of current hinders further heating of the wire material, and the pressure increase behind the SW front hinders further rapid expansion of wire explosion products. In the second scenario, development of breakdown occurs in the wire material vapor rather than in the surrounding medium. An example of the development of such a process can be observed when low-melting-point copper wire is exploded. The energy continues to be deposited in the wire explosion products, which supports their further explosive expansion. This can explain the noticeable difference in optical shadowgraphs of the discharge channel structure between electrically exploding copper and tungsten wires in air.