DETERMINATION OF AXIAL THERMAL PLASMA TEMPERATURES WITHOUT ABEL INVERSION

This paper presents an approximate formula for the determination of local axis temperatures of an inhomogeneous, axisymmetric, optically thin, local thermodynamic equilibrium plasma column without using the Abel inversion technique. The proposed method is straightforward and is based on recording the spatially integrated radiances of spectral lines. The formula is useful for high gradients thermal plasma columns of the type found in DC electric arcs or plasma jets of gaussian shaped temperature profile. The formulation permits a simple experimental arrangement for rapid monitoring or controlling parameters in industrial plasma devices or for the determination of emissivities and line transition probabilities. We also show that the method can be applied to spatially unstable arc discharges, where traditional techniques are difficult and cumbersome to apply.