Preparation and Lifetime Research of Diamond-like Carbon Stripper Foil

The diamond-like carbon(DLC) stripper foils with ~5 μg/cm² in thickness were produced by using the composite technology of the filtered cathodic vacuum arc(FCVA)- alternating current carbon arc(ACCA)-relaxation technique. The uniformity of the DLC foils were measured by the XP2U balance. The results show that the maximum inhomongeneity of DLC foils in the range of Φ100 mm is 8.82%. The microstructure of the DLC foils were measured by the scanning electron microscopy(SEM), Raman spectroscopy and X-ray photoelectron spectroscopy(XPS). The SEM images show that the DLC foils are smooth, and contain hardly droplets through the double 90° filters. The Raman spectrum indicates that the DLC foils are amorphous carbon films. The X-ray photoelectron spectrum indicates the sp³ bonds of the DLC foils exceed 70%. The irradiation lifetimes of the DLC stripper foils were tested with the heavy ion beams at the Beijing HI-13 Tandem Accelerator. The results indicate that the lifetime of the DLC stripper foils after relaxation is ~3 times of the DLC stripper foils before relaxation. The lifetime of DLC stripper foil is respectively 4 and 13 times of the carbon stripper foil for the ¹⁹⁷Au⁻ and ⁶³Cu⁻ ion beams(~9 MV, ~1 μA). The lifetime of DLC stripper foil is 2.6~10.0 times of the carbon stripper foil for the ¹⁰⁷Ag⁻、⁷⁰Ge⁻、⁴⁸Ti⁻、²⁸Si⁻ and ¹²⁷I⁻ ion beams. The heavier ions and the stronger beam current, the longer lifetime of DLC stripper foil compared with that of carbon stripper foil. The lifetime of the DLC stripper foils is related to the substrate bias voltage, and increases at first and then decreases with the increasing of the substrate bias voltage. The lifetime reaches the peak value when the substrate bias voltage is −400 V.