|Ph.D Thesis||Department of Physics|
|Supervisors:||Prof. Krasik Yakov|
|Prof. Emeritus Felsteiner Joshua|
|Full Thesis text|
The purpose of the research was the investigation of underwater electrical wire explosion (UEWE). The research was carried out using two high-current, high-power generators producing wire explosions in micro- and nanosecond timescale. The microsecond timescale experiments were carried out using a generator with stored energy of up to 2.4 kJ and maximum short circuit current of 100 kA. Maximal current densities j obtained during UEWE were of the order of 108 A/cm2 and maximal dI/dt ~ 50 A/ns.
The nanosecond timescale experiments were carried out using a generator with stored energy of up to 0.7 kJ and maximum short circuit current of 70 kA. Maximal current densities j obtained during UEWE were of the order of 109 A/cm2 and maximal dI/dt ~ 500 A/ns.
Shock wave pressure measurements were carried out using optical fast streak or frame photography of shock wave propagation, laser based methods, various probes based on the piezoelectric effect and other methods. The temperature of the discharge channel was estimated using the spectrum of the radiation emitted from the discharge in the visible and UV light range.
Hydrodynamic and magnetohydrodynamic simulations were extensively used to supplement the experimental data. Using the MHD simulations with the experimental results, equation of state models were checked and modernized in some cases.
Experiments in nanosecond timescale UEWE have shown that a deposition of 200 eV/atom by direct Joule heating into the wire materials becomes possible due to the combination of the advantages of using the water medium and the increase of the input power growth rate.
Experiments with exploding cylindrical wire arrays have shown that an amplification of the pressure of the shock waves generated in a single wire explosion can be amplified by a factor of > 20 by using the cumulative effect in the converging SWs. Simulations have shown that the interaction of a spherical converging SW in the water medium with a DT gas mixture target can result in the ignition of a thermonuclear reaction. The energy deposition into the water flow required for obtaining a 1014 reaction yield of the target material is only 10 kJ.