Converging shock wave focusing and interaction with a target

Abstract

Converging shock waves in liquids can be used efficiently in the research of the extreme state of matter and in various applications. In this paper, the recent results related to the interaction of a shock wave with plasma preliminarily formed in the vicinity of the shock wave convergence are presented. The shock wave is produced by the underwater electrical explosion of a spherical wire array. The plasma is generated prior to the shock wave's arrival by a low-pressure gas discharge inside a quartz capillary placed at the equatorial plane of the array. Analysis of the Stark broadening of Hα and Hβ spectral lines and line-to-continuum ratio, combined with the ratio of the relative intensities of carbon C III/C II and silicon Si III/Si II lines, were used to determine the plasma density and temperature evolution. It was found that during the first ∼200 ns with respect to the beginning of the plasma compression by the shock wave and when the spectral lines are resolved, the plasma density increases from 2 × 1017 cm−3 to 5 × 1017 cm−3, while the temperature remains at the same value of 3–4 eV. Further, following the model of an adiabatically imploding capillary, the plasma density increases >1019 cm−3, leading to the continuum spectra obtained experimentally, and the plasma temperature >30 eV at radii of compression of ≤20 μm. The data obtained indicate that the shock wave generated by the underwater electrical explosion of a spherical wire array retains its uniformity during the main part of its convergence.

Experimental Study of Energy Design Optimization for Underwater Electrical Shockwave for Fracturing Applications

“…Wire explosion underwater results in non-ideal plasma, optical emissions, heat, and strong shockwaves (SWs) in terms of the GPa level [4][5][6][7][8]. This method has several advantages over plasma blasting and other used techniques due to multiple reasons, including the generation of extremely high pressure, in addition to the uniform column of plasma provided by the water bath that enables the direct measurement of the non-ideal plasma conductivity [9][10][11][12][13][14].…”

Uniformity of cylindrical imploding underwater shockwaves at very small radii

“…11,12 Different methods (damage of different targets, spectroscopy of the obtained water plasma created by the convergence of the SSW) were applied to determine the water parameters in the vicinity of implosion. [13][14][15] Also, the SSW's time-of-flight to the axis (cylindrical wire array) or origin (spherical wire array) of implosion leading to intense light emission from compressed and heated water at those locations was used for comparison with the results of one dimensional (1D) and two dimensional (2D) Hydrodynamic (HD) simulations, coupled with the EOS of water and copper. 16 In these simulations, which considered symmetrical SSW convergence, only the energy deposition rate into the wires, calculated using the experimentally obtained resistive voltage and discharge current waveforms, was an input parameter.…”