Formation of beryllium-hydrogen ions in chemical sputtering from 20 to 420eV

0538080 - ÚFCH JH 2021 RIV NL eng J - Journal Article
Ballauf, L. - Hechenberger, F. - Stadlmayr, R. - Dittmar, T. - Daxner, M. - Zoettl, S. - Aumayr, F. - Herman, Zdeněk - Scheier, P.
Formation of beryllium-hydrogen ions in chemical sputtering from 20 to 420eV.
Nuclear Materials and Energy. Roč. 22, JAN 2020 (2020), č. článku 100722. E-ISSN 2352-1791
EU Projects: European Commission(XE) 633053 - EUROfusion
Institutional support: RVO:61388955
Keywords : surface-induced dissociation * room-temperature * heated surfaces * collisions * efficiency * tungsten * n-2(+) * ar+ * Low energy sputtering
OECD category: Physical chemistry
Impact factor: 2.320, year: 2020
Method of publishing: Open access

The formation of BeD+ in collisions of deuterium molecular ions with a beryllium surface at hyperthermal energies is investigated, using a purpose-built tandem mass spectrometer setup, ´´SurfTOF´´. In the manifold of products, hydrogen-containing molecules are of special interest in fusion devices. Our experiments show, that they can be formed in nearly all conditions comparable to plasma and wall temperature, with two mechanisms involved: First, BeD(+)is formed directly in a reaction of the D-2(+) projectiles with the Be surface, which is the main aspect of this work. There was no evidence found, that this particular mechanism relies on D implanted in the bulk Be. BeD2+ was not detected. The second reaction pathway produces BeH+. It is efficiently formed when H2O molecules are adsorbed on the surface, much less abundant for hydrocarbon adsorbates. The yield of Be+, BeH+ and BeD+ products, is measured as a function of several parameters: Scanning the impact energy from 20 to 426 eV reveals that the molecular BeD+ is preferably produced at low energies. At 20 eV, its abundance is three times higher than that of pure Be+. When the surface temperature is raised from 298 to 673 K, sputtering yields increase two orders of magnitude for both, Be+ and BeD+.
Permanent Link: http://hdl.handle.net/11104/0315899