This paper gives an overview of finding the discharge parameters equations and their effects on the design criteria of ETA as well as the realized design solutions. The aim of this study is to obtain information about the discharge parameters in an electrothermal gun by extending the previous models of different researches and analyze their equations. Different physical processes in confined high-pressure discharge analyzed. For a given discharge, ablation rate and plasma pressure,the tube length is limited. An analytical model is developed for confined high-pressure discharges operating in a quasi-steady state, in which the resulting plasma jet characteristics are steady at hydrodynamic timescales. This model allows the calculation of all the discharge parameters, such as ablation rate; plasma temperature; plasma sound velocity; density; current density and pressure, as a function of the "slowly varying" current and the tube dimensions. Good agreement for the results obtained between the theoreticalmodel, which is built, and the experimental results for global research.