Improved modelling of electrothermal plasma source with radiation transport

An improved one-dimensional, time-dependent model with radiation transport is developed and used to simulate the evolution and flow of Ohmically heated nonideal plasma in the capillary of an electrothermal (ET) plasma source operated in the ablation stabilized arc regime. The model uses the Ohmic input power, recovered from the experimentally measured impedance, as the sole driving force of the computations to circumvent depending on arguable theoretical models of the resistivity of nonideal plasma. A consistent model of the equation of state and thermodynamic functions of weakly nonideal multi-component plasma mixtures is implemented and used to calculate the thermodynamic properties of the ET plasma generated from the ablation of the capillary wall. The flow velocity at the bore exit is not allowed to exceed the local sound speed and no prior assumptions of choked-flow are made at the bore exit. The frequency-dependent and frequency-averaged opacities of the plasma have been calculated considering the basic atomic processes of photoionization, inverse bremsstrahlung, resonant photoabsorption as well as electron scattering. Radiation transport has been implemented by modelling the plasma column as a grey gas the emissivity of which is calculated using an effective beam length L_eb. The radiative heat flux escaping the surface of the grey plasma column is used to calculate the rate of the ablated mass improving the temporal behaviour of the calculated plasma parameters. Particular attention is devoted to investigating the ablation process and the evaluation of the so-called heat of ablation. Computational results are presented and discussed.