Development of long-life carbon stripper foils for uranium ion beams

Carbon foils (C-foils) are extensively used as charge strippers for heavy-ion beams at the RIKEN RI beam factory. Multi-layer polymer coated C-foils (PCC-foils) of 300 μg/cm2 carbon thickness were irradiated by a 11 MeV/nucleon 238U35+ beam and their lifetimes were measured. Using an atomic force microscope (AFM) and an electron probe microanalyzer (EPMA), it was observed that the surface property and cross-sectional image of the PCC-foils had changed after the irradiation. A rotating-cylinder stripper device, which was developed to further increase the lifetime of C-foils, was also tested.