Coaxial Energetic Ion Depostition of Superconducting Coatings on Copper RF Cavities for Particle Accelerators

75521-Radio frequency (rf) cavities are a key component in particle accelerators for fundamental high-energy physics research and medical applications. To enhance their capabilities, niobium coated, superconducting copper cavities have shown promise for supporting higher electric field gradients, compared to non-superconducting designs. However, a satisfactory coating method has not been developed that can deposit high-quality superconducting films to the insides of these cavities. To date, the maximum field gradient that can be supported in niobium coated copper cavities is about 15 MV/m, which is not satisfactory for future accelerator designs. This project will develop a deposition process for coating the inside of copper rf accelerator cavities with high-quality, superconducting films that will allow particle accelerators to achieve field gradients greater than 15 MV/m. In Phase I: (1) copper test samples and several sapphire witness plates will be coated with niobium films using a coaxial energetic deposition process; (2) the superconducting transition temperature, Tc, and Residual Resistivity Ratio (RRR) for the films will be measured to determine the superconducting properties; (3) scanning electron microscope and x-ray diffraction analysis will be performed to assess the general film properties; and (4) actual rf accelerator cavities will be coated with niobium. Commercial Applications and Other Benefits as described by the awardee: The superconducting thin film coatings for accelerator cavities should reduce the development and operating costs of particle accelerators, and allow them to achieve higher particle energies. Other applications include enhanced protective coatings for coal gasification, olefin manufacturing, and gun barrels for the military.