Absorption spectroscopy on an expanding argon arc plasma

Absorption spectroscopy was used to det. the population densities of the resonant and metastable 4s levels in an expanding cascaded arc Ar plasma. An exptl. method using optical multichannel anal. is presented. Measurements were done on the Ar lines between 790 and 860 nm. The use of these strong lines necessitates a correction procedure for the nonlinear relation between the measured absorption values and population densities. To this end, in the present method an exact line shape anal. is not necessary. Ar 4s densities were detd. in the order of 1017/m3 at a background pressure of 40 Pa. [on SciFinder (R)