Hybrid Cavities for Axion Detectors

Abstract

Hybrid cavities, cavities with a layer of superconductor applied on top of the OFHC copper, are studied. The quality factor of a single thin layer and of a multilayer superconductor/insulator stack are estimated. The results for these thin-film coatings are not good. However, if the superconductor (either multilayer or single layer) were separated from the copper by a thick dielectric spacer, one that is a fraction of the wavelength at the cavity resonant frequency, extremely high quality factors could be obtained.