Experimental study of H atom recombination on different surfaces in relation to H negative ion production

Abstract : Volume production of H negative ions is mostly attributed to the dissociative attachment of electrons to ro-vibrationally excited molecules. Apart from the main formation path for enriching the plasma with these molecules (i.e. radiative decay of singlet states excited by collisions with energetic electrons, EV excitation), an additional formation process refers to recombination of hydrogen atoms on the surface of materials which face the plasma. In this work, the importance of the later process is evaluated by considering various materials. Pyrex, Stainless Steel, Highly Oriented Pyrolytic Graphite (HOPG), and Yttrium, are sequentially tested in the ECR-driven H negative ion source ROSAE III. This source is specially designed to promote as much as possible surface recombination only on the surface of the specimen under test. Optical emission spectroscopy does prove a high degree of dissociation in this source. Furthermore, electron and negative ion densities are measured by means of electrostatic probe and laser photodetachment, respectively. The effectiveness of the above materials for the production of ro-vibrational states is thus evaluated indirectly, i.e. by comparing the values of the produced negative ion densities, assuming H production through DA mainly. The results suggest that, under the present conditions, the formation of ro-vibrational states is apparently dominated by process other than surface recombination.
Type de document :
Article dans une revue
AIP Conference Proceedings, American Institute of Physics, 2017, 1869, pp.020011. 〈10.1063/1.4995717〉
Liste complète des métadonnées

https://hal-insu.archives-ouvertes.fr/insu-01616032
Contributeur : Catherine Cardon <>
Soumis le : vendredi 13 octobre 2017 - 08:34:40
Dernière modification le : samedi 2 juin 2018 - 11:16:01

Identifiants

Citation

S. Aleiferis, J. Bentounes, Stéphane Béchu, P. Svarnas, Alexandre Bés, et al.. Experimental study of H atom recombination on different surfaces in relation to H negative ion production. AIP Conference Proceedings, American Institute of Physics, 2017, 1869, pp.020011. 〈10.1063/1.4995717〉. 〈insu-01616032〉

Partager

Métriques

Consultations de la notice

242