Underwater wire electrical explosions and the ensuing shockwaves are useful for studying matter in extreme conditions. Using an array of wires, interactions between the shockwaves can result in the formation of dense, high velocity water jets, able to apply pressure and potentially penetrate various target media. To demonstrate the scope of applications this technique could be used, Maler et al. have performed the first detailed study of the water jets formed in these underwater wire array explosions.

To measure the jet velocities of the various setups, the group backlit the water tank and took successive shadow images of the jets. By varying the composition and size of the wires in the array, their geometry, the water level above array and through the use of shock reflectors, the velocity of the water jets was increased – whilst collimators placed above the array enabled the jets formation to be studied and further optimized.

The researchers found one of the most notable impacts was that of the wire composition, particularly when the wires were made with aluminum instead of copper, they underwent combustion, which further increased the jet velocity. In one case, the resulting jet was strong enough to shatter a 4mm thick stainless-steel reflector.

“These are the results we want to see – stuff breaking because we inserted too much energy into a region,” said author Daniel Maler.

Though they don’t fully understand the mechanism of jet production yet, Maler and his collaborators said the applications are vast. In future experiments, they are looking to try out other scenarios and configurations, such as using heavy water and letting two jets collide, which may allow for low-energy measurements of deuterium-deuterium cross-sections.

Source: “Generation of supersonic jets from underwater electrical explosions of wire arrays,” by Daniel Maler, Sergey Efimov, Alexander Rososhek, Simon N. Bland, and Yakov E. Krasik, Physics of Plasmas (2021). The article can be accessed at https://doi.org/10.1063/5.0050430.