|Ph.D Student||Antonov Oleg|
|Subject||Underwater Electrical Wire Array Explosion and Shock|
Wave Generation in Water
|Department||Department of Physics||Supervisor||Professor Yakov Krasik|
|Full Thesis text|
The subject of single wire electrical explosion in different background media has already been studied in many laboratories around the world for more than 50 years. In our Plasma laboratory electrical wire explosion is studied in water. The latter allows one to keep high energy density deposition into the wire during the explosion due to the small compressibility of water and the high value of electric breakdown field preventing the formation of a plasma channel in the water, typical for wire explosion in gas or vacuum. Large energy density deposition into the wire leads to the formation of warm dense matter and finally, non-ideal plasma with a coupling coefficient significantly larger than 1. This state of matter is under continuous intense research due to the interesting phenomena involved and its importance for astrophysics, studies of transport coefficients of a material at extreme conditions accompanied by phase transitions solid-liquid-vapor-plasma, Equation of State and due to such important application as inertial confinement fusion.
The electrical explosion of a wire in water is accompanied by ~105 cm/s radial expansion of the wire resulting in the generation of a strong shock wave in water. In the case of a cylindrical wire array, due to overlapping of the shock wave generated by each wire, one obtains the generation of a single cylindrical symmetrical shock wave which converges to formation of extremely high pressure (up to 1011 Pa), density (up to 3 g/cm3) and temperature (up to 2 eV) of water in the vicinity of the implosion axis.
The subject of the presented thesis is an experimental and numerical research of underwater electrical explosion of a spherical wire array and converging strong shock waves which generation is accompanied by this explosion. The application of spherical wire array underwater electrical explosion allows one to obtain much larger values of pressure, density and temperature of water in the vicinity of the origin of the converging shock wave’s implosion than in the case of a cylindrical shock wave implosion. In this research, two pulsed power highcurrent generators with different rates of energy density deposition were used. Parameters of water in the vicinity of the convergence origin were studied by the time-of-flight of the shock wave which was compared with the results of numerical hydrodynamic simulations, using visible spectroscopy of the plasma formed in the origin’s vicinity and by the deformation of the target placed in the equatorial plane of the spherical wire array. The obtained experimental data and the results of numerical simulations showed that indeed, one can expect to obtain an extreme state of water in the vicinity of implosion characterized by pressure of up to 1012 Pa, water density and temperature up to 10 g/cm3 and 10 eV, respectively.