Results related to the generation of an extreme state of water with pressure up to (4.3 ± 0.2)·1011 Pa, density up to 4.2 ± 0.1 g/cm3, and temperature up to 2.2 ± 0.1 eV in the vicinity of the implosion axis of a converging strong shock wave are reported. The shock wave was produced by the underwater electrical explosion of a cylindrical Cu wire array. A ∼8 kJ pulse generator with a current amplitude ≤550 kA and rise time of 350 ns was used to explode arrays having varying lengths, radii, and number of wires. Hydrodynamic numerical simulations coupled to the experimental data of the shock wave propagation in water, rate of energy deposition into the array, and light emission from the compressed water in the vicinity of the implosion axis were used to determine the pressure, density, and temperature profiles during the implosion. Results of a comparison between these parameters obtained with the SESAME and quantum molecular dynamics data bases of equation of state for water are reported as well. Also, the dependences of the maximal pressure in the vicinity of the implosion axes on the array radius and the deposited energy density per unit length are reported.
The results of experiments on the ignition of aluminum micro-particles' combustion by underwater electrical wire explosion (UEWE) are reported. A compact sub-microsecond timescale duration high-current (240 kA) pulsed power generator was used to explode copper and aluminum wires electrically in different aluminum powder suspensions. The combustion of the aluminum micro-particles was characterized by a target time-of-flight method and optical measurements of the exploding wire and aluminum suspension light emission. It was shown that, by using a proper solution and type of aluminum powder, this method allows aluminum micro-particle combustion in the estimated range of 32-79 % efficiency.
The generation of an extreme water state ͑130 GPa, 5000 K, and 3.4 g / cm 3 ͒ which is characterized as dense plasma at the axis of a converging shock wave is reported. A 4 kJ pulse generator was used to explode a 40 Cu-wire array, generating a cylindrical shock wave. The measured shock wave trajectory and energy deposited into the water flow were used in hydrodynamic simulations coupled with the equation of state to determine the water parameters. The temperature estimated using the emission data of water in the vicinity of the implosion axis agrees with the simulation results, indicating shock wave symmetry in such extreme conditions.
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