RF Superconducting Materials Research at SLAC

A materials research program is described. The program objectives are to evaluate materials and develop processing and fabrication techniques which it will be economically feasible to use in the construction of a high-gradient (10 MeV/ft) two-mile linear accelerator. RF properties are evaluated by cavity Q measurements at selected frequencies in the range 3 to 11 GHz. Techniques for reducing field emission are being sought. At present, this phenomenon is being studied by making dc measurements at room temperature. RF superconducting properties are known to be very sensitive functions of material purity and crystal structure. For this reason, various methods of deposition, surface purification and heat treatment are being tried. Most work is being done with lead and niobium, but technetium plating is being actively investigated.