MgB$_{2}$ Coating by HPCVD for 1.3-GHz Superconducting RF Cavities

While MgB ₂ possesses promising material parameters for SRF cavities with higher Q, higher gradient, and higher operation temperatures than Nb cavities, such cavity properties have not been demonstrated using MgB $_{2}$ . As part of a continuing effort to fabricate MgB $_{2}$ -coated SRF cavities by hybrid physical-chemical vapor deposition (HPCVD), we present here an HPCVD system design for coating the inside wall of 1.3-GHz copper cavities with MgB $_{2}$ . The cavity is heated using a pair of clamshell resistive heaters that directly contact the cavity body. The new heater design is more compact and requires less power to reach the deposition temperature ( $\sim 500\,^\circ$ C for MgB $_{2}$ deposition on copper.) Preliminary test of MgB $_{2}$ films grown on small copper substrates, mounted at different locations on the cavity, shows $T_{c}$ of 28.4 $\sim$ 34.3 K, measured by AC susceptibility.