A two-dimensional spatial resolution was used to analyze the time dependence of the spectral emission of an atmospheric pressure glow (APG) discharge in helium with impurities. By Penning ionization through metastable helium atoms, the N 2 + line at 391.4 nm was excited. A set of measurements taken during uniform APG operation were discussed. A radial spreading of the discharge during the current pulse and the formation of a ringlike, radially propagating cathode layer late in the current pulse were shown by the results.
Bibliographical noteFunding Information:
The authors are grateful to Professor J. Heberlein for valuable discussions. This work was supported by the Department of Energy under Grant No. DE-FG02-00ER54583 and by the University of Minnesota Supercomputing Institute.