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Vibrational Kinetics, electron dynamics and elementary processes in H2 and D2 Plasmas for Negative Ion Production: Modelling Aspects
M.Capitelli1,2, R.Celiberto1,4, O.De Pascale2, P.Diomede1, F.Esposito2, A.Gicquel3, C.Gorse1, K.Hassouni3, A.Laricchiuta2, S.Longo1, D.Pagano1, M.Rutigliano2, M.Cacciatore1,2
1Department of Chemistry, University of Bari, Bari, Italy
2CSCP-IMIP(CNR), Sezione Territoriale di Bari, Bari, Italy
3LIMHP-CNRS, Université Paris Nord, Villetaneuse, France
4Politecnico di Bari, Bari, Italy
Abstract: Old and new problems in the physics of multicusp magnetic sources for the production of negative H-/D- ions are presented and discussed. We emphasize particularly, in this kind of plasmas, both the vibrational and electron non equilibrium energy distributions, the role of Rydberg states in enhancing the negative ion production, the production of vibrationally excited states by the Eley-Rideal mechanism, and the enhancement of negative ion concentrations in pulsed discharges.
In appendix I recent cross sections calculations for elementary processes and the theoretical determination of hydrogen recombination probability on graphite surface are illustrated.
In appendix II two types of sources are modeled: the first one is a classical negative ion source in which the plasma is generated by thermoemitted electrons; in the second one, electrons already present in the mixture are accelerated by an RF field to sufficiently high energy to ionize the gas molecules.
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