Low Temperature MgB2 Deposition for SRF

Most radio-frequency (RF) particle accelerators worldwide rely on normal conducting RF cavities to accelerate the particle beam. A few large research accelerators such as the Continuous Electron Beam Accelerator Facility (CEBAF) at Thomas Jefferson National Laboratory (JLAB) use superconducting radio frequency (SRF) accelerating cavities. SRF cavities consume less power than normal cavities to produce a given accelerating gradient, leading to smaller accelerators or faster particles. Currently, niobium is the only superconductor the SRF community accepts. Other higher temperature superconductors like magnesium diboride may replace niobium, but the only clear way to take advantage of magnesium diboride in SRF cavities is to coat a structural material with a thin film. Normally, magnesium diboride is deposited at high temperature to produce high quality films; however, the processing temperature is well above the thermal limits for copper, which is the preferred SRF cavity material for future accelerators due to its cost, thermal conductivity, and electrical conductivity. This project will explore a low temperature method to deposit magnesium diboride. Once magnesium diboride films are grown and characterized on coupons, SRF testing in a TE013-like cavity will determine whether the magnesium diboride can replace niobium in future SRF particle accelerators. Commercial Applications and other Benefits as described by the awardee: If magnesium diboride were qualified as a replacement superconductor for niobium, a 10× reduction in SRF material costs and a 2× reduction in refrigeration cost could be realized. Then, the magnesium diboride SRF technology could be transitioned to the 17,000 commercial particle accelerators worldwide.