Optimum ion implantation and annealing conditions for stimulating secondary negative ion emission

The type, energy, ion dose, and heating temperature required to ensure a stable minimum work function of a surface in one experimental cycle (at least 2–3 min) are determined. Secondary ion mass spectrograms are recorded using Cs$^+$, Ba$^+$, and Ar$^+$ ions. Cu, Al, and Mo samples are studied. The optimum ion implantation conditions and the activation temperature that provide a stable minimum work function of the sample surfaces are found. The samples implanted by Ba$^+$ ions withstand higher temperature and current loads than the samples implanted by Cs$^+$ ions. However, the work function in the case of Cs$^+$ ions decreases stronger (to 1.9 eV). It is shown that neutral sputtered particles do not leave the surface at $e\varphi\le$ 1.85–1.90 eV.