Final Technical Report

Abstract

The objective of this project is to develop a MgB 2 superconducting RF (SRF) cavity technology. Compared to the currently-used SRF material niobium, MgB 2 has a much higher T c of 40 K, a lower residual resistivity (< 0.1 µΩcm), and a higher thermodynamic critical field Hc. SRF cavities with MgB2 coatings have the potentials for higher Q, higher gradient, and higher operation temperatures. A MgB 2 SRF technology can significantly reduce the operating costs of particle accelerators when these potentials are realized. In this project, we have made significant progresses in the deposition of large-area (2” diameter) MgB 2 films for RF characterizations, deposition of MgB 2 films on metal substrates including Nb, Mo, Ta, and stainless steel, enhancement of Hc1 with decreasing MgB 2 film thickness, fabrication and characterization of MgB 2 /MgO multilayers, and deposition of MgB2 films of excellent superconducting properties on the wall of a 6-GHz RF cavity. These results have laid foundation for a MgB 2 superconducting SRF cavity technology.