Electrical explosion in confined space: From warm dense matter to fragmentation

The physical image of the confined electrical explosion in the source region is depicted. Metallic plasma/vapor dynamics and its fragmentation effect (on a confining structure) under μs-timescale are diagnosed via high-speed photography, electrophysical, and spectral measurements. When adding a 1-mm-thick Teflon tube outside the exploding wire, the growth of spatial heterogeneity via electro-thermal instability is largely compressed, and the deposited energy almost doubled from about 85 to 150 J. During the short period after breakdown, considerable energy depositing into the confined space, e.g., 100 J for 0.1 cm3, drives the fast inflation and burst of the 0.5 g confining tube to ∼500 m/s (kinetic energy of ∼62.5 J). Intense plasma jet eruption with a supersonic speed >1.5 km/s and induced shock waves of 2-3 km/s are observed from cracks of the inflated tube. In addition, the erupted plasma jets gradually evolve Rayleigh-Taylor instability and finally cause turbulent mixing with the ambient medium. This mechanism is very likely to explain the plasma cavity evolution in underwater explosion. Interestingly, although the confining effect of water is stronger than a Teflon tube, the latter has a better response to the high-rate impulse loading and absorbs more deposited energy by deformation, phase transition, and acceleration.