Actinometric method for measuring hydrogen-atom density in a glow discharge plasma

The actinometric method is proposed for measuring the hydrogen-atom density in a plasma of self-sustained glow discharge in hydrogen and its mixtures with the use of Kr atoms as an actinometer of H atoms. The use of krypton f or this purpose is advantageous over the commonly used argon actinometry. F irst, the excitation energies of the H(n = 3) and H(n = 4) levels almost co incide with the excitation energies of the Kr(5p') and Kr(6p) levels, respe ctively. Second, the wavelengths of the emission from the H(n = 4) and Kr(6 p) levels lie in the range 420.0-490.0 nm, convenient for spectral analysis ; moreover, these wavelengths are fairly close to each other, which makes t he calibration of the optical system unnecessary when these levels are used for the actinometry. The electron excitation rate coefficients are calcula ted for the H, Kr, and Ar levels of interest, including the dissociative ex citation of hydrogen atoms and stepwise excitation of krypton atoms. The ap plicability conditions of the actinometric technique are determined. it is shown that the ratios between the excitation rate coefficients of hydrogen and argon atoms depend on the reduced electric held, which complicates the measurements of the hydrogen-atom density when argon atoms are used as acti nometer particles. The proposed technique is used to measure the hydrogen-a tom density in a self-sustained glow discharge in an experiment on depositi ng diamond films with the use of CO + Kr + H-2 mixtures.