Determination of the number densities of argon metastables in argon-hydrogen plasma by absorption and self-absorption methods

The number densities of Ar 3s(2)3p(5)4s levels have been measured by means of two methods: a self-absorption method with a mirror behind the discharge vessel and an absorption method with a high-frequency electrodeless discharge lamp. Concentrations ranging from 6 x 10(7) - 4 x 10(9) cm(-3) were obtained for the Ar 3s(2)3p(5)4s levels, depending on the argon content ( 10 - 100% Ar) in Ar/ H-2 microwave plasma. The populations of various sublevels of measured resonant and metastable states coincide within the experimental errors. It was observed that values from measurements of both methods are in good agreement.