Strongly coupled copper plasma generated by underwater electrical wire explosion

Abstract

A number of theoretical approaches to the analysis of the parameters of a discharge channel consisting of strongly coupled plasma generated in the process of underwater electrical wire explosion are presented. The analysis is based on experimental results obtained from discharges employing Cu wire. The obtained experimental data included electrical measurements and optical observations from which information about the dynamics of the water flow was extrapolated. Numerical calculation based on a 1D magnetohydrodynamic model was used to simulate the process of underwater wire explosion. A wide range conductivity model was applied in this calculation and good agreement with a set of experimental data was obtained. A method of determining the average temperature of the discharge channel based on this model and experimental results is proposed, and the limits of this method's applicability are discussed.

Spectroscopy of a plasma formed in the vicinity of implosion of the shock wave generated by underwater electrical explosion of spherical wire array

“…The main advantages of this approach are related to the large electric filed breakdown value (>300 kV/cm) of water and its low compressibility (adiabatic index c ¼ 7.15), which allows an extremely high energy density deposition into the exploding wire to be achieved. Indeed, recent experimental, analytical and numerical studies [11][12][13][14][15] of underwater electrical wire explosion showed that, using pulsed power generators with a stored energy of only a few kJ, an extreme state of matter, i.e., up to 500 eV/atom and pressure of 5 Â 10 9 Pa can be obtained.…”

Addressing water vaporization in the vicinity of an exploding wire

“…The minimum wire heating rate considered in calculations was similar to that obtained in the electrical wire explosion experiments in Refs. [12][13][14] .…”

“…8 In the case of underwater electrical wire explosion in the microsecond and nanosecond time scales, it was shown that high pressures generated in the surrounding water during the discharge might suppress the generation of the plasma shell. [12][13][14] In these papers, pressure generated by the expanding material of the exploded wire was reported. The estimated velocity of the wire expansion was ϳ10 4 cm/ s and the pressure generated by such a piston was of the order of a few 10 9 Pa. Obviously, at these pressures the problem of water vaporization is automatically abolished since the critical pressure of water is ϳ2.5 ϫ 10 7 Pa.…”

“…However, the rapid expansion of the wire and, respectively, the generation of high pressure waves begin after the wire material reaches the critical point of the liquid-vapor curve. 12 For Cu, the critical temperature is ϳ1 eV, thus the explosion and generation of high pressure in surrounding water start only after the wire material has been heated to this high temperature. The natural question arising in this connection lies in the possible vaporization of the water layer adjacent to the heated wire prior to the onset of the explosion and the subsequent wire expansion.…”

Magnetically launched flyer plate technique for probing electrical conductivity of compressed copper

“…More advanced methods, for example, the Ziman model 29,30 in conjunction with average atom models like Inferno 31 is more accurate than the semi-empirical models, but are subject to large variations in their answers based on which potentials and assumptions are chosen. At high temperatures, these codes are often quite adequate (Grinenko et al 32 ), but in the compressed solid at modest temperature (several thousand Kelvin) they are less reliable. In all cases, experimental validation of results is still required.…”