The Efficacy of Hydrodynamic Compression Using a Conical Cavity

A technique for controlled hydrodynamic compression of gases using a conical cavity driven by liquid metal was proposed by Lei (2016) as a convenient, low-cost, repetitive instrument to achieve a very high compression ratio of up to 109\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$10^9$$\end{document}. If the compression is fully adiabatic, such compression will raise the gas temperature by a factor of 106\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$10^6$$\end{document} for monoatomic gases. In this paper, we develop a 0-D semi-analytic model to examine in detail the adiabatic assumption, taking into account in particular the physical processes of dissociation, ionization, radiation, and energy exchange between the compressed gas and the wall, and provide an assessment of the temperature of the gas or plasma that may be attainable using the technique. The numerical results show that these physical processes drastically lower the temperature attainable. Nevertheless, the results still indicate that final gas temperature of more than 10 eV, and volume-compression-ratio more than 106\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$10^6$$\end{document}, are still attainable that might enable a number of interesting applications. The modeling results also revealing some interesting effects of partially ionized gases under high ratio of compression.