MgB2-Coated RF Cavities for Free Electron Laser

Free electron lasers (FEL) made from Nb cavities offer high performance, but they are complex, bulky, and expensive. For Navy FEL applications, where footprint, power consumption, and cost are severely constrained and reliability is of great importance there is a critical need for an alternative to Nb. MgB2 is a recently discovered superconductor with a high critical temperature and critical field. These and other favorable materials properties suggest that MgB2-coated RF cavities have the potential to outperform Nb-based cavities in terms of operating temperature, size, cost, and complexity. This program’s objective is to produce a conceptual design for an MgB2 thin film vacuum deposition chamber to enable fabrication of a proof-of-principle, MgB2-coated, pillbox-shaped cavity. In phase II of this program we will implement the design, and a suitable deposition chamber will be constructed. MgB2-coated pillbox cavities fabricated in this system will be tested at temperatures from 4.2 K to Tc and at high power. In this manner the feasibility of depositing non-flat high-quality MgB2 thin films on the inside of curved surfaces will be demonstrated, which is a crucial step in the implementation of the MgB2-RF-cavities concept for FEL applications.