Superconducting Radiofrequency Acceleration

Development of SCRF cavity production yield for two threshold fields. The gradient of 35 MV/m has been specified for the ILC.

Superconducting radiofrequency cavities operating at 1.3 GHz have seen a tremendous development in performance since the launch of an intense R&D effort in the early 1990s. At DESY the TESLA collaboration has advanced the accelerating field to values of roughly 25 MV/m and more, well exceeding the gradient to be used for the European XFEL.

The International Linear Collider (ILC) has specified a gradient of 35 MV/m as an acceptance test in the vertical cryostat. Such fields and higher have been shown to be attainable in individual samples. Over the past few years the Global Design Effort for the ILC has dramatically improved the yield - as shown above. The production specification for the 800 cavities of the European XFEL is deemed to yield cavities of the desired maximum field and a quality of 2x1010. They will this form the largest sample for systematic performance characterization.

The research programme launched in the framework of the AvH professorship addresses this topic: achievement of the highest gradient and the highest Q0 under established and reproducible production conditions. The research will profit from the performance statistics provides by the cavities of the European XFEL and will be supplemented by 24 cavities that will be manufactured specifically for post-processing to understand and remedy performance limitations.