Barrier Discharge in Helium at Medium Pressures. Afterglow Spectroscopy

Abstract

The decaying plasma that is produced by the dielectric barrier discharge (DBD) in helium across a cylindrical tube at a pressure of helium 1–40 Тorr has been spectroscopically investigated. The radical difference between the nature of the barrier discharge afterglow and longitudinal pulse discharge afterglow at the same plasma electron density has been demonstrated. It has been shown that this effect is due to the abnormally low density of metastable He(2¹S₀, ³S₁) atoms in the plasma that is produced by DBD. In such an experiment, it is possible to observe a purely recombination afterglow that is free of processes involving metastable atoms, which is fundamentally important for solving the problem of helium afterglow.