Nanosecond time scale, high power electrical wire explosion in water

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.

Temporal shock wave analysis produced by copper exploding wires in air at atmospheric pressure

“…Different plasma characteristics are visible on the features of the recorded light including the shock wave and the plasma channel. 16,17 We present here the measures of the exterior front radii as a function of time that include the expansion plasma and the shock wave stages. One of the most visible features is the reduction of the light absorption region at the beginning of the plasma expansion when the initial charging voltage increases its magnitude; 6 also, an increase in the rate of the radii of the shock wave is visible.…”

“…Because the shock wave generated has rich information about the shock wave generator system, different wire materials, dimensions, and surrounding media were studied in the past. [14][15][16][17][18] Here, we focus the study on a copper exploding wire at atmospheric pressure. The diameter of wire and charged voltage of the electrical system are used simultaneously as parameters in these experiments.…”

Generation of highly symmetric, cylindrically convergent shockwaves in water

“…2D r-θ Lagrangian hydrodynamics simulations were compared with the trajectory of the shockwave to estimate the parameters including the pressure, density, temperature and energy density in the water behind the shock 22,23 . The simulations were based on the finite volume method and included conservation of mass, momentum and energy coupled with high pressure equations of state for copper and water.…”

Electrical Exploding Nickel and Tungsten Wires in Air and Water

“…The plasma shell forces the current away from the wire core and reduces joule energy deposition. On the other hand, Grinenko et al (4) reported that the plasma shell was significantly reduced for wires exploded in water, resulting in significant energy deposition. Clearly, to improve energy deposition, it is necessary to minimize current diversion from the wire core to the plasma shell during wire explosion.…”

“…In a number of papers, attempts were made to study the influence of a surrounding medium on the energy deposited during electrical wire explosions (1)(2)(3)(4). A recent report by Sarkisov et al (3) on the electrical explosion of titanium wires showed that the energy deposited into the wire doubled for explosions in air when compared to that deposited for explosions in vacuum.…”