The study presents a physico-mathematical model that describes the dynamics of the impulse plasma generated in a coaxial accelerator under the impulse plasma deposition process conditions. According to the model, the plasma spreads out in the form of a dynamically moving electric current sheet that is accelerated by the Lorentz force. During the process the shape of this current-carrying interface undergoes deformation as a result of the working gas flow upon its surface. The deformation degree depends on the parameters of the plasma generation process. The model assumes that the plasma is monofluidic and that the shape of the current sheet is two-dimensional, although infinitely thin. The proposed model, which is still being modified, does not yet take into account the effect of plasma being enriched with the products of electrode erosion. Even at this stage, however, the results obtained from the computer simulation using this model are in semi-quantitative agreement with experimental results.