Nanosecond time scale, high power electrical wire explosion in water

TLDR

The study presents experimental and magnetohydrodynamic simulation results of nanosecond‑scale underwater electrical explosions of Al, Cu, and W wires. A 100 kA water‑forming line generator was used, with discharge channel evolution and surface temperature measured by streak shadow imaging and a fast photodiode, and material conductivity calculated to match simulation and experiment. The experiments achieved a maximum current rise rate of 500 A/ns and Joule heating power of 6 GW, depositing up to 60× the atomization enthalpy—three times higher than vacuum explosions—while 1D MHD simulations matched discharge parameters and revealed that material conductivity varies strongly with energy deposition rate.

Abstract

Experimental and magnetohydrodynamic simulation results of nanosecond time scale underwater electrical explosions of Al, Cu, and W wires are presented. A water forming line generator with current amplitude up to 100kA was used. The maximum current rise rate and maximum Joule heating power achieved during wire explosions were dI∕dt⩽500A∕ns and 6GW, respectively. Extremely high energy deposition of up to 60 times the atomization enthalpy was registered compared to the best reported result of 20 times the atomization enthalpy for energy deposition with a vacuum wire explosion. Discharge channel evolution and surface temperature were analyzed by streak shadow imaging and by a fast photodiode with a set of interference filters, respectively. A 1D magnetohydrodynamic simulation demonstrated good agreement with experimental parameters such as discharge channel current, voltage, radius, and temperature. Material conductivity was calculated to produce the best correlation between the simulated and experimentally obtained voltage. It is shown that material conductivity may significantly vary as a function of energy deposition rate.