Study of Ar I and Ne I Spectral Lines Shapes in the Cathode Sheath Region of Abnormal Glow Discharge

Abstract

One of the distinguished features of the cathode sheath (CS) region of abnormal glow discharges (GD) is the distribution of electric field strength F, which is of crucial importance for charged particles acceleration, their trajectories, kinetic energies and collisions with other particles and cathode sputtering. All these processes are relevant for the operation of GD, as well as for numerous applications in the field of spectroscopic analysis, plasma etching, thin film deposition and depth profiling of cathode material. Thus, the importance of nonperturbing technique for F distribution measurement in a tiny CS region was recognized long time ago. Within this work, a simple technique, based on the standard optical emission spectroscopy (OES) and standard laboratory equipment, has been used for F mapping in the CS region of abnormal GDs of Grimm type in argon and neon. This is in essence the well known Lo Surdo technique used for studies of Stark effect, but employed with a modern CCD detector [1-3]. The profiles of two neutral argon lines (Ar I 518.775 nm and 522.127 nm) and several neutral neon lines were observed in the CS region sideon to the discharge axis. It was found that some of the studied lines manifest the Stark splitting, and that all lines exhibit Stark shifts, whose measured values are subsequently used for estimating the distributions of the electric field strength in the cathode sheath region of the studied glow discharges.