Time-dependent one-dimensional modeling of pulsed plasma discharge in a capillary plasma device

Abstract

The capillary plasma device is a relatively new technology for producing plasma vapor after ablating the capillary bore wall using high-magnitude pulsed electric power. Time-dependent behavior of the plasma flow in the capillary plasma device is investigated numerically by solving the radially averaged one-dimensional inviscid conservative equations of gas dynamics using LCPFCT gas dynamics code, which utilizes flux corrected transport (FCT) in solving generalized continuity equations. Joule heating and the mass ablation from the bore wall are incorporated in the numerical modeling. The thermodynamic and transport properties of the plasma are evaluated based on the assumption of local thermodynamic equilibrium and weakly nonideal plasma. At the bore exit, the sonic boundary condition is applied due to the thermally choked flow. The computational results yield the details of the plasma discharge behavior in the capillary bore including high-pressure and high-temperature plasma conditions at the bore exit. The plasma composition at the bore exit shows the significant ionization of the polycarbonate atomic species to the first ionization level, but the second ionization is found to be negligible. Computed mass ablation from the bore wall agrees well with the experimentally determined mass loss, but the assumption of blackbody radiation from the bulk plasma yields the overprediction in mass ablation.