Measurement of the DC Stark shift for visible Nel lines and electric field distribution in the cathode sheath of an abnormal glow discharge

We present the results of an experimental study of the DC Stark shift for seven visible NeI lines in the plane cathode sheath region of an abnormal glow discharge operated in neon with a small admixture of hydrogen. The electric field (up to 13.4 kV cm(-1)) in the cathode sheath region is measured from the p-polarized profile of the H alpha line of hydrogen using the Stark polarization spectroscopy technique. Within the realized range of the electric field, the NeI lines exhibit a quadratic Stark effect. The values of coefficients, correlating Stark shift and electric field strength, were determined, enabling their future use for unknown electric field strength measurements. Among the studied lines, so far only the Stark effect analysis of the NeI 511.367 nm line has been reported, in which case our results are in good agreement with the best fit formula proposed by Jager and Windholz (1984 Phys. Scr. 29 344) for one out of three Stark components detected under our experimental conditions

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

Ar I and Ne I spectral line shapes for an abnormal glow discharge diagnostics

We report the results of an Ar I and Ne I line shape study in an abnormal glow discharge operating in argon and 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 show spectral line shifting and sometimes simultaneous shifting and splitting in the cathode fall region of the glow discharge. The results of the measured line shift with available data for the dc Stark effect are used for measurement of electric field strength in the cathode fall region of the glow discharge. Electron temperatures of 2860 K and 4770 K in the negative glow region of argon and neon discharges, respectively, were determined from the relative intensities of Ar I or Ne I lines using the Boltzmann plot technique. An electron number density of approximate to 10(20) m(-3) (+/- 25%) in the negative glow region of the argon discharge was determined from the widths of two plasma-broadened Ar I lines using theoretical Stark broadening data. The end-on recorded line profiles show 10-40% 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

Complex UV Ne II line shapes in the cathode sheath of an abnormal glow discharge

We report results of an experimental and theoretical study of complex UV line shapes of Ne II 369.421 nm, Ne II 371.308 nm and Ne II 372.711 nm lines in the cathode sheath (CS) region of an abnormal glow discharge in pure neon. The experimental profiles were studied by means of the optical emission spectroscopy (OES) in conjunction with an iterative CS kinetic model. It is shown that our theoretical model describes the experimental line shapes and that, with the aid of the measured Stark shifts of atomic neon lines, it can be used for the determination of the most important CS parameters (e.g. the thickness of the CS region, distribution of electric field, and the gas temperature). We draw attention to the possibility of determining the electric field strength in CS from the width of the pedestal of the complex line profiles