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

Abstract

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.

Estimation of the maximum electric field strength in the cathode sheath of a Grimm-type glow discharge by end-on view optical emission spectroscopy in neon and argon

“…21,22 Further investigations were extended to the inuence of the Stark effect on the non-hydrogen lines starting with helium, [23][24][25][26] towards heavier elements like neon and argon. [27][28][29][30][31] In a most recent development, [32][33][34] the inuence of the CS electric eld on the complex shapes of Ne II lines is reported as a tool for electric eld mapping.…”

“…To this end, we assumed a simple linear regression electric field distribution model F ( d ) = F max (1 − d / d c )described in standard textbooks, taking into account that typically around 90% of the applied discharge voltage gets consumed in the CS to produce the electric field. Following several reported experimental results, 18–21,23,24,32 which show that the F ( d ) exhibits a plateau at the maximum value F max , stretching from the cathode surface to the distance of about 20% of the total CS length d c , we hereby additionally assumed, for the purpose of simplicity, that the F = F max remains constant within the first 20% of the CS (see Fig. 1).…”