Selective Laser Spectroscopy of Neutral Near-Wall Layers

This paper deals with the diagnosis of neutral near-wall boundary layers in high-temperature plants. This is relevant for low-pressure fusion plants, involving the stability analysis of the first reactor wall to heat fluxes from inhomogeneous plasma in the vacuum chamber. These problems are relevant in the development of electrode plasma devices and in modern devices with high-temperature flows of neutral gases in boundary layers. The peculiarity of inhomogeneous boundary layers is the presence of discrete wave spectra, which can be used to determine the parameters of the medium. Within the framework of this work, a connection between the standing wave spectrum at selective laser reflection and the spatial distribution of atom concentration in the boundary layer was established. It is shown that high values of the specular reflection coefficient allow its effective use for diagnostics of neutral near-wall boundary layers. Plasma diagnostics in low-pressure fusion plants is related to the determination of the stability of the first wall of a fusion reactor to thermal flows of inhomogeneous plasma near the vacuum chamber wall. The same questions arise at creation of electrode plasma devices and in modern devices with high-temperature flows of neutral gases in boundary layers. A characteristic feature of inhomogeneous boundary layers is the presence of discrete spectra of different wave modes excited in them, which can be effectively used to determine the distributions of the parameters of the boundary layer medium. In the present work, a connection between the spectrum of standing waves of selective laser reflection and the spatial distribution of atomic concentration in the boundary layer has been established.