Hybrid Monte Carlo—fluid modeling network for an argon/hydrogen direct current glow discharge

Abstract

A hybrid modeling network, consisting of several Monte Carlo and fluid models, is developed for a dc glow discharge typically used for mass spectrometry, in a mixture of Ar with 1% H 2. The species described in the model are: electrons; Ar + ions and fast Ar atoms; ArH +, H +, H 2 + and H 3 + ions; H atoms; and H 2 molecules; as well as Ar metastable atoms. Sixty-three reactions are taken into account in the model. The calculated densities of the various plasma species are presented. The electrons and Ar + ions are the dominant charged species in the plasma, with densities in the order of 10 11 cm −3. Furthermore, the ArH + and H 3 + ions have a relatively high density (in the order of a few 10 10 cm −3), whereas the H + and H 2 + densities are negligible (order of 10 6–10 7 cm −3). The dissociation degree of the H 2 molecules was calculated to be very low (approx. 0.02%), yielding H 2 and H densities in the order of 10 14 and 10 11 cm −3, respectively. The relative contribution of different production and loss processes of the electrons, different ions, H atoms, H 2 molecules and Ar metastable atoms are also calculated. Finally, a comparison is made between a pure Ar discharge and a glow discharge in a mixture of Ar+1% H 2.