Temperature optimization for superconducting cavities

Since our previous analysis of optimized operating temperature of superconducting cavities in an accelerator a decade ago, significant additional information has been discovered about SRF cavities. The most significant is the Q/sub 0/ (quality factor) shift across the Lambda line at higher gradients as a result of a slope in Q/sub 0/ vs. E/sub acc/ above Lambda. This is a result of the changing heat conduction conditions. We discuss temperature optimizations as a function of gradient and frequency. The refrigeration hardware impacts and changes in cycle efficiency are presented.