First experiments with Cs doped Mo as surface converter for negative hydrogen ion sources

L. Schiesko (1) , Gilles Cartry (2) , C. Hopf (1) , T. Höschen (1) , G. Meisl (1) , O. Encke (1) , B. Heinemann (1) , K. Achkasov (2) , P. Amsalem (2) , U. Fantz (1)

1 IPP - Max-Planck-Institut für Plasmaphysik [Garching]
2 PIIM - Physique des interactions ioniques et moléculaires

A study was conducted on the properties of molybdenum implanted with caesium as an approach to reduce the Cs consumption of negative hydrogen ion sources based on evaporated Cs. The depth profiles of the implanted Cs were simulated by SDTrimSP and compared to XPS depth profiling and forward modelling. Good agreement between the measured depth profiles and modelling was found. In particular, one year after implantation, the depth profiles showed no signs of Cs diffusion into the molybdenum, suggesting long term stability of the implanted Cs atoms. The H − surface generation mechanisms on the implanted samples in hydrogen plasma and the stability of the H − yield during low power hydrogen plasma discharges as long as four hours were investigated. Moreover, an estimation of the work function reduction by the Cs implantation and a comparison of the relative negative ion yields between the implanted samples and highly oriented pyrolitic graphite (HOPG) were performed, leading to the conclusion that the development of Cs doped Mo compounds as surface converter materials should be continued.

Domains: Physics [physics]; Physics [physics]; Plasma Physics [physics.plasm-ph]

L. Schiesko, Gilles Cartry, C. Hopf, T. Höschen, G. Meisl, et al.. First experiments with Cs doped Mo as surface converter for negative hydrogen ion sources. Journal of Applied Physics, 2015, 118 (7), pp.073303. ⟨10.1063/1.4928861⟩. ⟨hal-03617714⟩