Underwater electrical wire explosion

Abstract

Summary form only given. We report on experimental and computer modeling research of underwater electrical wire explosions (UEWE) which present a promising method tor generation of strong shock waves (SSW) and non-ideal plasma. Micro-and nano-second time scale generators for UEWE of Al, Cu and W wires were employed. A mus (6 kJ stored energy, current of 80 kA, rise time of 2.5 mus) and ns (400J stored energy, current of 100 kA, rise time of 50 ns) generators were used in mus and ns time scale experiments, respectively. Different time-and space-resolved electrical, optical and spectroscopic diagnostics were used to study parameters of expanding discharge channel and generated SSW. Obtained scaling laws for explosion parameters suggest that the increase in the discharge power rate leads to an increase in the generated pressure amplitudes. Furthermore, increasing the power rate allows for an extremely high energy deposition, namely up to 200 eV/atom was registered in ns Cu UEWE. The high value of the energy deposition is due to the absence of shunting plasma shell which presents in vacuum electrical wire explosions. It was shown that up to 15% of the stored energy is converted top the energy of the SSW. In order to amplify the pressures generated by the exploding wires, accumulation effect in imploding cylindrical wire arrays was implied. High pressures of converging SSW up to 0.2 Mbar were registered near the array axis. Results of a simplified model indicate that, using a spherical geometry setup with 7.5 mm external radius of the water layer and ~35 kJ total deposited energy, 1.5-1014 neutron yield during ~1.5 ns time can be achieved. These re suits suggest that ignition of DT target by implosion in water medium can be considered as a promising method for inertial confinement fusion.