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The augmentation of a ballistic process, based on the well known solid propellant burning by an electrothermal (ET) energy source, is the subject of an experimental and theoretical investigation to obtain improved launching techniques. The plasma jet formation method, the internal ballistics modeling approach and the experimental test bed are described. Experimental results are disclosed showing the enhanced burning rate of a solid propellant ignited and augmented by the injection of plasma jets. We also present preliminary experimental evidence of improved performance of the new proposed method over that of conventional ballistics using solid propellant alone.

A time-dependent quasi-one-dimensional model is developed for studying high- pressure discharges in ablative capillaries used, for example, as plasma sources in electrothermal launchers. The main features of the model are (i) consideration of ablation effects in each of the continuity, momentum and energy equations; (ii) use of a non-ideal equation of state; and (iii) consideration of space- and time-dependent ionization.

The non-ideal continuity, momentum and energy equations describing plasma characteristics in confined high-pressure discharges in cylindrical ablative capillaries were solved numerically. The model equations used included (a) viscous and radiative and thermal conduction effects, (b) space dependent ionization and correction to Spitzer's electrical conductivity, and (c) non-ideal equation of state, as provided by SESAME library. For illustration, the case of polyethylene capillaries and discharge parameters appropriate for electrothermal launchers were considered. Analysis of the results indicated the consideration of the non-ideal equation of state to have significant consequences on the plasma characteristics. The sensitivity of these effects to variations in the discharge parameters was then studied and the results are also presented here. In the last part of the work the authors present the results of the implementation of a method aimed to determine self-consistent boundary conditions at the ends of the capillary as well as of the investigation of their effect on the solutions obtained.

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