Multiply charged ion-induced secondary electron emission from metals relevant for laser ion source beam diagnostics

The number of secondary electrons, γ, emitted when multiply charged ions impact on metallic probe surface was measured to make the quantitative ion diagnostics based on this process more precise. The electron yield γ(q,Ei) was measured for Taq+ and Xeq+ ions (q=6–41) in the region of ion kinetic energy per atomic mass up to Ei/A∼34 keV/amu. For highly charged Xeq+ ions (q>16), a minimum of the electron yield, γMIN, was observed in its dependence on Ei. With increasing q, the γMIN shifts to higher energies. The comparison of available data for Nq+, Neq+, Arq+, Xeq+, and Auq+ ions shows that one can create a similarity law describing the dependence of γMIN for those elements in the Ei/A representation. The value of γ/q evaluated from compiled data ranges from ≈0.3 to ≈3.5 in dependence on q and Ei.