Optical investigations of multicomponent plasma of capillary discharge. Supersonic outflow regime

Аннотация

We present the results of spectroscopic investigations of the plasma of an impulse discharge in a capillary with an ablation wall made of carbon-containing polymer, within the discharge pulse parameters providing the supersonic flow regime of a plasma jet. Based on a 2D-matrix high resolution spectra containing H_α, Cu I, Cu II, C I, C II, and CN and the Swan molecular bands, we obtain spatiotemporal distributions of the electron number density and the plasma temperature in the capillary and the supersonic plasma jet. We reveal the peculiarities of the spatial distribution of the electron number density and of the spectral component intensity within both above stated zones, conditioned, in particular, by achievement, in the hot central zone, of an electron temperature above the “normal” temperature, as well as by essential nonisobaricity of the initial section of the plasma jet. The emission properties of the high-temperature jet core–the intensities and the profiles of the H_α and H_β Balmer lines, relative intensities of the C II and O II ion lines–registered with high temporal (10 μs) and spatial (20–30 μm) resolution make it possible to discover the main regularities in the spatiotemporal distributions of pressure, temperature, and ionization degree in the capillary and in the supersonic heterogeneous jet of the erosion discharge. Due to the presence in the flow of the molecular components displaying their emission properties at the jet periphery, we manage to obtain information on the plasma parameters within the zone of formation of the “intercepting” shocks in the supersonic jet.