Lifetime improvement of nitrided carbon stripper foils by ion-beam sputtering with a binary gas mixture

The lifetimes of our carbon stripper foils (10–25 μg/cm2) prepared by reactive nitrogen ion-beam sputtering were distributed in a wide range. Expressed in units of integrated beam current received, lifetimes of 750±400 mC/cm2 were usual for a 3.2 MeV Ne+ beam. This wide distribution of lifetimes have been improved by applying a binary gas mixture (N2+Ne) for sputtering of carbon. With high reproducibility, lifetimes of 475±80 mC/cm2, approximately 15 times those of the best standard commercially available foils, have been achieved. We have also investigated the influence light-element admixtures had on the lifetimes of carbon stripper foils.