MEASUREMENT OF DENSITY DISTRIBUTION OF METASTABLE HE ATOM IN A PLANE-PARALLEL HOLLOW-CATHODE HE PLASMA

The density distribution of the singlet metastable He atom in a plane- parallel hollow cathode plasma was measured by the laser-induced fluor escence (LIF) method along with the absorption method, where the align ment of the atom excited by the linearly polarized laser light, the se lf-absorption of the fluorescence light by the 2(1)S atom in the plasm a and the effect of the atomic collisions as well as the electronic on es were considered. The alignment is demonstrated to play important ro les in the determination of distribution of the metastable He atom den sity in a glow plasma with the electron density of (2.0+/-0.5) x 10(11 ) cm(-3), temperature of 1.3 eV and gas pressure of 0.7 Torr. Applicab ility of a simplified model used for the analysis of the present exper iment was also discussed.