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

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% H2. The species described in the model are: electrons; Ar+ ions and fast Ar atoms; ArH+, H+, H2+ and H3+ ions; H atoms; and H2 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 1011 cm−3. Furthermore, the ArH+ and H3+ ions have a relatively high density (in the order of a few 1010 cm−3), whereas the H+ and H2+ densities are negligible (order of 106–107 cm−3). The dissociation degree of the H2 molecules was calculated to be very low (approx. 0.02%), yielding H2 and H densities in the order of 1014 and 1011 cm−3, respectively. The relative contribution of different production and loss processes of the electrons, different ions, H atoms, H2 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% H2.