Numerical validation of a self absorption model for optically thick plasmas

Numerical validation of a self absorption model for high-pressure plasma-based light sources was discussed. It was assumed that the plasma is cylindrically symmetric. The side-on intensity emitted at wavelength ¿ along a plasma diameter perpendicular to the axis was considered. This intensity was given by the one-dimensional solution to the radiation transfer equation. The results are independent of the existence of local thermodynamic equilibrium (LTE) and are valid for the resonance lines too

Numerical validation of a self-absorption model for plasma radiation

This paper investigates the reliability of deducing the emissivity at the peaks of a self-reversed emission line from a simple empirical one-parameter approximation for the source function. The theory of spectral line shape formation owing to self-absorption in inhomogeneous axially symmetric plasma layers was reformulated and readily calculable expressions were obtained. In the case of self-reversed lines, the emissivity at the line maximum was calculated using different relative distributions for the densities of the absorbing and independently emitting atoms. The results were compared with those calculated using a source function described by a simple exponential law, the exponent of which is known as the inhomogeneity parameter. The obtained difference in the emissivity is less than 3%, which implies a difference in the (density-ratio) temperature between the line-levels better than 0.5%. Therefore, if the inhomogeneity parameter is known, the line emissivity can be deduced from the one-parameter approximation for the source function with reasonable accuracy. The effect of the structure of the plasma layer on the emissivity as well as the lateral dependence of the inhomogeneity parameter was also studied through numerical simulatio

Numerical validation of a self absorption model for optically thick plasmas

Numerical validation of a self absorption model for high-pressure plasma-based light sources was discussed. It was assumed that the plasma is cylindrically symmetric. The side-on intensity emitted at wavelength ¿ along a plasma diameter perpendicular to the axis was considered. This intensity was given by the one-dimensional solution to the radiation transfer equation. The results are independent of the existence of local thermodynamic equilibrium (LTE) and are valid for the resonance lines too

Numerical validation of a self absorption model for optically thick plasmas

Numerical validation of a self absorption model for high-pressure plasma-based light sources was discussed. It was assumed that the plasma is cylindrically symmetric. The side-on intensity emitted at wavelength ¿ along a plasma diameter perpendicular to the axis was considered. This intensity was given by the one-dimensional solution to the radiation transfer equation. The results are independent of the existence of local thermodynamic equilibrium (LTE) and are valid for the resonance lines too

Source function approximations and their impact on the shape of self-reversed atomic lines

The shape of optically thick atomic lines emitted from inhomogeneous plasmas is calculated using both a heuristic one-parameter approximation (OPA) for the source function and the Bartels approximation. The results are compared with those obtained from solving the radiation transfer equation using selected trial source functions. The accuracy of the OPA is proved to be higher than that of the Bartels, particularly within the central line region, and independent of the equilibrium conditions in the plasma. The results open up the possibility of a realistic analysis of self-reversed lines and their application to plasma diagnostics