Preparation of ultra-thin DLC target for laser ion acceleration

Self-supporting diamond-like-carbon (DLC) films have been manufactured successfully using the filtered cathodic vacuum arc system, which are ideal targets for laser phase-stable acceleration regime. The film is deposited at room temperature with a -32 V substrate bias voltage. The deposition rate is about 0.002 nm per pulse. Practically, the NaCl is deposited first as a sacrificial layer before carbon deposition. A holder with round holes is used to support the DLC film after the NaCl layer is dissolved in the water. Films with thickness 5-50 nm can mount over the apertures with a diameter up to 1 mm and the success rate is about 70%. The structure and roughness of the film have been measured by the Raman spectrum and atomic force microscope.