Superelastic collisions of electrons with the c 3Πu metastable state in hydrogen dc positive column Original Research Article

We investigated the effect of superelastic electronic collisions of electrons, with the c 3Πu state of the H2 molecule, on the electron energy distribution function (eedf) of a dc positive column. We use a recently calculated set of electronic superelastic collision cross-sections [C.S. Sartori, F.J. da Paixão, M.A.P. Lima, Phys. Rev. A 55 (1997) 3243] to study the effect of these collisions on the eedf, the transport parameters, ionization and dissociation rates. We include two possible pathways, c 3Πu → b 3Σ+u and c 3Πu → X 1Σ+g, for superelastic collisions of electrons with molecules in the metastable state. Cross-sections of the order of 10−14 cm2 at low energy enhance the eedf tail by superelastic electronic collisions, in particular for low reduced electric field E/N. This result changes considerably the dissociation and ionization rates by six orders of magnitude in the region from 10 to 50 Td.