Molecular-beam sampling of a hollow-cathode discharge in argon as a plasma diagnostic and a source for fast neutrals

Abstract
Velocity analysis of the molecular beam is done with a time‐of‐flight method. The measured velocity distribution of the fast neutral atoms is described by the sum of two Maxwell‐Boltzmann distributions with temperatures on the order of 0.25 and 1 eV, respectively. This bimodal distribution is attributed to an overpopulation of the high‐energy tail of the ion velocity distribution. The measured intensities of the fast neutrals vary between 5×1014 and 7×1015 (molecules s−1 sr−1).