A high Tc superconducting resonator for a compact hydrogen maser

The authors describe the development, testing, and evaluation of a superconducting compact hydrogen maser resonator made from electrophoretic Y₁Ba₂Cu₃O_7-δ This compact loop-gap resonator, based on a previously suggested maser resonator (H.E. Peters, 1978), is made superconducting using an electrophoretic process developed for the deposition of thick-film polycrystalline high-T_c superconductors on large nonplanar metallic substrates. At 77 K, cavity quality factors were obtained comparable to those of standard size, room-temperature TE₀₁₁ maser resonators. The fields of the resonators were studied using numerical techniques to determine the dependence of the filling factor and the cavity quality factor on the geometric parameters. This information is used to optimize the cavity design with respect to the effects of thermal radiation on the maser performance at 77 K