Defect-oriented carbon stripper foil development

Carbon foils produced by electron beam evaporation of approximately 5 μg/cm2 thickness are regularly in use as stripper foils in the 15UD Pelletron Accelerator at Nuclear Science Centre. This report examines the role of defects produced by the ion beams in influencing usable life of these carbon foils. The life of the foils has been estimated by measuring the transmitted ion current at the high-energy end of the 15UD Pelletron. The lifetime of carbon stripper foils entirely depend on the defects produced by the ions. A relation between the onset of the degradation of current transmission and the accumulated defects has been established. An improved type of carbon stripper foils might be obtained by the introduction of thin C60 layers.