Numerical simulation of capillary plasma flow generated by high-current pulsed power

Pulsed plasma discharge in the interior region of electrothermal-chemical gun is numerically investigated with the one-dimensional time-dependent mathematical modeling that includes the Joule heating of plasma column and the mass ablation of bore wall. Sonic boundary condition is utilized because flow is expected to be choked at the bore exit. In the evaluation of thermodynamic and transport properties, plasma state is assumed to be in local thermal equilibrium due to high pressure and is found to be weakly nonideal. The computational results show that capillary plasma flow at the bore exit is partially ionized high temperature and high pressure discharge. Many predicted data including arc resistance, energy deposition, and bore wall mass ablation are favorably compared with the measurements on total 8 shots of gun firings with different levels of energy deposition ranging from 5.3 to 47 kJ. Temporal evolution of pressure shows transient effect in the calculations but the effect is minimal compared to the significant transient effect in the pressure measurements. However, maximum pressure is in good agreement with measured data.