Details

Autor(en) / Beteiligte

• Baldwin, M.J.
• Lynch, T.C.
• Doerner, R.P.
• Yu, J.H.

Titel

Nanostructure formation on tungsten exposed to low-pressure rf helium plasmas: A study of ion energy threshold and early stage growth

Ist Teil von

• Journal of nuclear materials, 2011-08, Vol.415 (1), p.S104-S107

Ort / Verlag

Amsterdam: Elsevier B.V

Erscheinungsjahr

2011

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Nanostructure formation on W targets is explored as a function of He+ impact energy, εi, in the range 20⩽εi⩽57eV. Six targets are exposed at 1120K for 6h to pure He plasmas, generated by a low-pressure rf Helicon source. One target is additionally exposed to Ar plasma pre-treatment. It is found that He ions of impact energy 32–37eV are necessary for nanostructure formation to be observed in this type of plasma, as determined by SEM. At 57eV a nanostructured surface forms readily (similar to that observed by Baldwin and Doerner, Nuclear Fusion 48 (2008) 035001 in the PISCES–B device), but growth is retarded in the Ar pre-treatment case. Thermal desorption shows that nanostructuring is accompanied by increased trapping of He in degenerate vacancies and clusters, but is reduced by a factor of 8 as a result of Ar pre-treatment.