First Results of the SRF Wafer Test Cavity for the Characterization of Superconductors

The wafer test cavity was designed as a short sample test system that could create a reproducible environment for the testing of superconducting materials above the Bardeen-Cooper- Schrieffer limit of niobium. The results of the sapphire test cavity showed that the dielectric was too lossy, and thus, the original design had to be altered to make operation feasible with current hardware and achieve ~200 mT. The new design was fabricated at Thomas Jefferson National Accelerator Facility and was cryogenically tested. After four tests, the cavity was able to produce a 6.6-mT field with a Q of 3.96 * 10⁸. Although lower than anticipated, in comparison to other TE01 cavities, this result is quite encouraging. Multipacting and coupling were limitations, but current work is pursuing the elimination of these complications. This document will expound upon the new design, mathematical simulations, testing of the cavity, complications, results, and future work.