Ne I spectral line shapes in Grimm-type glow discharge

We report the results of five Ne I line shapes study in an abnormal Grimm-type glow discharge operating in neon. The spectral lines were observed along the axis of a cylindrical glow discharge parallel (side-on) and perpendicular (end-on) to the cathode surface. The side-on spectra showed a spectral line shift and sometimes a simultaneous shift and split in the cathode fall region of the glow discharge. The results of the measured line shift with the available data for the dc Stark effect were used to estimate the electric field strength in the cathode fall region of the glow discharge. The end-on recorded line profiles showed up to 30% larger half-widths than the side-on recorded line profiles from the negative glow. This effect is a result of the superposition of line emission in the cathode fall region under the influence of the dc Stark effect on the line profile from the negative glow. In addition, wavy features at the far wing in the direction of dc Stark shift were detected. All observed phenomena related to end-on line shapes in Grimm discharge were related quantitatively to the dc Stark effect in the cathode fall region and plasma line broadening in the negative glow region.