Underwater electrical wire explosion

Abstract

A brief review of the results obtained in recent research of underwater electrical wire explosions using microsecond and nanosecond generators is presented. It was shown that the increase in the rate of energy input into the exploding wire allows one to increase the wire temperature and amplitude of shock waves (SWs). Estimated energy deposition into Cu and Al wire material of up to 200 eV/atom was achieved. In microsecond time scale wire explosion, a good agreement was attained between the wire resistance calculated using the equation of state (EOS) and that obtained experimentally. Conversely, in nanosecond time scale wire explosion, the wire resistance of EOS was modified in order to fit experimental data. Analysis of the emitted radiation showed that black body approximation cannot be used to characterize exploding wire radiation. It was found that 24% of the deposited energy is transferred into the water flow's mechanical energy. Also, it was shown that converging SWs formed by the explosion of cylindrical wire arrays can be used to achieve a pressure up to 250 kbar at the axis of implosion. Hydrodynamic simulations showed that with the use of relatively moderate pulsed power generators with stored energy of several hundred kilojoules, a pressure of several megabar can be achieved at the axis of implosion.

Diagnostics of a converging strong shock wave generated by underwater explosion of spherical wire array

“…2. One can see that the discharge is aperiodic, which is typical for underwater electrical explosion of wires 18,19 characterized by fast phase transitions of exploding wires: solid state-liquid-vapor-plasma. The main energy deposition to the exploding wires occurs during the formation of plasma that is rather low-temperature (several eV) and low-ionized, i.e., the resistance of each exploded wire increases up to 8 X.…”

“…First, when the fiber was placed in the original wire array having a diameter of 30 mm, we obtained [see waveform (a) in Fig. 3] a drastic decrease in the laser intensity starting at time delay s d $ 0.45 ls with respect to the beginning of the wires' explosion (i.e., with respect to the beginning of the explosion accompanied by the generation of SSWs and at the time when a fast decrease in the discharge current is obtained 18,19 ), followed by a rather sharp and short ($100 ns time duration) recovery of the light intensity (first peak). The decrease in the light intensity can be explained by the fiber's decreased transparency (change of density and, respectively, refraction index) because of its interaction with SWs generated by the explosion of adjacent wires.…”

Experimental evaluation of near wellbore stimulation – using electrical explosion shockwave on tight sand reservoir

“…This strips the blockage attached to the surface of the seepage channel, reduces capillary force and surface tension, improves percolation ability and promotes gas desorption. Repeated action induces fatigue fracture, decreases various mechanical properties and expands the effective area of various functions [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31].…”

“…It would be very difficult to exceed the aforementioned efficiency in the case of electrical discharge in water. Nevertheless, Krasik with coworkers [7] conducted a research of underwater electrical wire explosions using microsecond and nanosecond generators. It was observed that the increase in the rate of energy input into the exploding wire allows one to increase the wire temperature and amplitude of shock waves.…”

Experiments on plasma dynamics of electrical wire explosion in air

“…The highenergy density plasmas in Z-pinches could be applied for intense x-ray sources [7], astrophysics research [8], inertial confinement fusion [9], etc. While a major driving force of researching electrical explosions was to ascertain the early stage of Z-pinches, the abundant physical and chemical processes during the explosion also draw scholars' attention to studying the subjects of shock waves [10,11], nanomaterial preparations [12], plasma ignition [13], etc. For the above industrial applications, the pulsed power generator is usually compact and convenient for scholars to pursue fundamental research in their laboratories, and the electrical current density (energy deposition rate) could be relatively small (slow explosion, <10 8 A/ cm 2 ).…”