A procedure for rapid evaluation of carbon stripper foils

Abstract

Lifetime measurements on carbon foils can become prohibitively time consuming and expensive with conventional particle accelerator beams. Therefore, a method has been developed which utilizes a beam of low energy (20 keV) nitrogen ions which allows tests to be conducted on relatively inexpensive equipment at very high damage rates. The beam is obtained from a General Ionex Model 1080 Sputterbell. Beam currents of the order of 1 μA cm −2 lead to failure of glow-discharge type foils on a time scale of, typically, 5–10 min. Lifetime ratios for glow-discharge versus evaporated foils obtained with this technique are in good agreement with those obtained with higher energy beams. Relative lifetimes for high energy and low energy bombardments are also found to be in good agreement with those predicted by damage energy calculations. The technique is currently being applied to the testing of glow discharge foils made with different feed gases and discharge conditions.