Electrodynamic Acceleration of a Dielectric Body by Arc Plasma in a System of Railgun Configuration

Electrodynamic acceleration of the arc plasma was studied in a system of railgun to high-speed acceleration of dielectric bodies. The efficiency of acceleration of a body, placed between parallel rails of a magnetoplasma accelerator, depends on the arc plasma properties. A physical model was developed for a high-current discharge migrating between the rails considering the coupling the processes between in the electrodes and in the plasma, as well as phenomena in the layers near the electrodes. In contrast to the previously published studies, the model take in account the mutual phenomena of mass and heat transfer near the walls and formation of the arc plasma using kinetic approach of copper electrode ablation. A self-consistent mathematical approach was developed to determine the parameters of the moving plasma and of the working surfaces. The calculations showed that the plasma and attached body velocity increases linearly with arc current I up to certain value I. Then the rate of plasma velocity rise decreased. At current about 10⁶A, the plasma velocity tends to saturation with current at velocity range of (7-9)$\times$10⁵cm/s depending on rail length (1-3m), which is in accordance with the experimentally observed limiting of the velocity for larger arc currents.