Stark effect of Ar I lines for electric field strength diagnostics in the cathode sheath of glow discharge

Faculty of Physics, University of Belgrade - Studentski trg 12-16, 11000 Belgrade, Serbia

^(a) nikolas@ff.bg.ac.rs

Received: 1 September 2017
Accepted: 11 October 2017

Abstract

We present a study of argon glow discharge which shows that measured wavenumber DC Stark shifts of two neutral argon lines, Ar I 518.75 nm and Ar I 522.127 nm, can be used for reliable determination of the electric field strength F distribution in the cathode sheath region of the discharge. In order to experimentally determine the coefficient c in quadratic correlation , manifested in a low field range (up to 15 kV/cm), the discharge is seeded with a small admixture of hydrogen, and the values of F are measured via Stark polarization spectroscopy of the hydrogen Balmer beta line. Once known, this can be used for the determination of F by a simple and inexpensive spectroscopic Stark shift measurement in discharges with other argon admixtures or pure argon. Reported shift results are in good agreement with data extrapolated from measurements performed at high electric fields (over 100 kV/cm) by Windholz (Phys. Scr., 21 (1980) 67).