Semi-analytical modelling and simulation of the evolution and flow of Ohmically-heated non-ideal plasmas in electrothermal guns

In this paper, the Ohmic power input to the discharge capillary is recovered and used to analyse the basic processes involved in electrothermal (ET) plasma devices operated in an ablation-controlled-arc regime. Such an interplay between theory and experiment is necessary to reduce the number of reasons which might be responsible for the reported discrepancies between theory and experiment, as well as to illuminate the subject of ablation controlled arcs. A consistent methodology for determining detailed composition and thermodynamic functions of the non-ideal plasma generated in such devices is presented and used in the present computations. Different non-ideality effects, due to Debye-Hückel corrections in the Gibbs free energy, which have been ignored in prior publications, have been taken into account. A semi-analytical model for an ET plasma source with non-ideal effects is described and incorporated into a comprehensive computer code to simulate plasma evolution and flow in the discharge capillary. The model is one-dimensional, time dependent and uses the recovered Ohmic power input in the source term of the energy equation. The developed code has been used to investigate the ablation process and has shown the inappropriateness of a widely used ablation model. Code predictions for different plasma parameters are presented, discussed, and compared to available experimental data.