Temperature Determination in an Inductively Coupled rf Plasma

Abstract
Simultaneous relative radiances of the Hβ, Hγ, and Hδ spectral lines of hydrogen were measured sequentially at various lateral positions in an inductively coupled rf argon-hydrogen plasma operated at atmospheric pressure (12 kW, 9 MHz). Measurements to take self-absorption into account were also performed. By applying an Abel integral inversion, a radial radiance profile for each line was obtained. With the two-line temperature method, simultaneous temperature profiles were obtained from each of the three line-pairs. The difference between these three sets of values and the negative values obtained for the Hγ, Hδ pair indicates that thermal equilibrium does not exist in this plasma.