Abstract

Recently, we reported on the properties of atomic hydrogen lines as produced in an electric hollow cathode discharge.¹ The principal finding there was the manifestation of highly articulated threefold line shapes with an extraordinary wing development not observed in the positive column of the same discharge. In the far wings of H_α, for example, the observed Doppler shifts indicated translational energies well in excess of 100 eV. Also noted for lines of the Balmer series was a difference in line shape for the case of observations made parallel to the cathode surface as opposed to those made perpendicular to that surface. In particular, while the parallel observations gave symmetric, unshifted lines, the perpendicular observations gave asymmetric blue-shifted lines. At present, we are examining the detailed structure of the blue-shifted lines as well as changes which are produced in the lines by alterations of cathode surface conditions. A comparison of results will be made with some very recent work of Cappelli et al.² who have noted Doppler-broadened line shapes of atomic hydrogen in a parallel-plate radio-frequency discharge by means of a hole drilled in one of the discharge electrodes.

© 1985 Optical Society of America