| AVS 59th Annual International Symposium and Exhibition | |
| Vacuum Technology | Wednesday Sessions |
| Session VT+AS+SS-WeM |
| Session: | Surface Analysis and Vacuum Manufacturing for Accelerators |
| Presenter: | Z. Li, College of William and Mary |
| Authors: | Z. Li, College of William and Mary W.M. Roach, College of William and Mary D.B. Beringer, College of William and Mary C. Clavero, College of William and Mary R.A. Lukaszew, College of William and Mary |
| Correspondent: | Click to Email |
Linear accelerators that are used in high-energy or nuclear physics experiments use superconducting radio frequency (SRF) cavities made with bulk Nb. However, as technology is improved for bulk Nb cavities, the accelerating gradient for these cavities is reaching the fundamental limit of 50 MV/m. Since the critical surface of Nb in SRF cavities is less than one micron, it is possible to use thin films and multilayers to overcome the accelerating gradient limit. It has been proposed to apply a superconductor-insulator-superconductor (SIS) multi-layer structure onto Nb based cavities in order to provide an improved lower critical field (Hc1) that will shield the Nb and therefore allow for an increase in the accelerating gradient [1]. NbN is one of the superconductors that may be implemented in this SIS structure. However, the choice of insulator is crucial in determining the performance of NbN thin films. Here, we present our study of epitaxial thin films prepared on both MgO and AlN templates. The effect of substrate choice on microstructure and superconducting properties is explored in order to determine which insulator provides optimal performance of NbN thin films for SRF applications.
[1] A. Gurevich, Appl. Phys. Lett. 88, 012511 (2006).