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

Abstract

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