Mass Spectrometry of the Negative Glow of a Cylindrical Hollow Cathode Discharge

摘要

Positive ions were extracted from the negative glow (NG) of a cylindrical hollow cathode discharge through a plane sampling probe and analyzed. The discharge was operated in pure Argon with about 0.1% of H2O. Principal ions were Ar+, Ar++, Ar2+, ArH+, H2O+, and H3O+. Individual ion currents were measured as functions of the probe potential U (sub b), at different discharge currents (2 to 7 mA) and gas pressures (0.05 to 0.5 torr). At probe potentials above +15 V no ions from the NG reached the probe, but electrons were accelerated so that ionization of the neutral gas could arise in and behind the orifice. The Ar++ current as a function of U (sub b) together with other results suggested the presence of very fast electrons.