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A. Qayyum, W. Schustereder, C. Mair, P. Scheier, T. Märk, S. Cernusca, Hp. Winter, F. Aumayr:
"Electron emission and molecuar fragmentation during hydrogen and deuterium ion impact on carbon surfaces";
Journal of Nuclear Materials, 313-316 (2003), 670 - 674.

Molecular fragmentation and electron emission during hydrogen ion impact on graphite surfaces has been investigated
in the eV to keV impact energy region typical for fusion edge plasma conditions. As a target surface graphite
tiles for the Tokamak experiment Tore Supra in CEA-Cadarache/France and highly oriented pyrolytic graphite
(HOPG) have been used. For both surfaces studied, the experimentally observed threshold for electron emission is at
about 50 eV/amu impact energy. Electron emission from the high conductivity side of the carbon tile is 15-20% less as
compared to its low conductivity side, whereas results for HOPG are generally between these two cases. Deuterium and
hydrogen ions are almost equally e.ective in liberating electrons from graphite when comparing results for the same
impact velocity. Surface-induced dissociation of deuterium ions D.3
upon impact on Tore Supra graphite tiles, in the
collision energy range of 20-100 eV, produced only atomic fragment ions D.. The other possible fragment ion D.2
could
not be observed.
2003 Elsevier Science B.V. All rights reserved.
PACS: 34.50.Dy; 79.20.Rf
Keywords: Ion-surface collisions; Electron emission; Surface induced dissociation; Molecular ions; Carbon surfaces; Hydrogen

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