Superconducting radio frequency (SRF) cavities underpin many modern particle accelerators, enabling highly efficient acceleration with high duty cycle or continuous wave operation. However, this technology relies almost exclusively on bulk niobium cavities operating at around 2 K, bringing significant capital and operational costs while performance increasingly approaches theoretical limits. Thin film SRF technology offers an alternative route to more sustainable accelerators by decoupling RF performance from the bulk, enabling the use of cheaper substrates (such as copper) and alternative superconducting materials (e.g. Nb3Sn) with the potential for higher temperature operation.
This talk introduces the importance of thin film SRF and outlines the ongoing research programme at Daresbury Laboratory. During material development, tests must first be carried out on small samples, where substrate preparation and deposition parameters can be optimised before committing to full cavity tests. A key metric is the RF surface resistance, which must be measured under cryogenic conditions (3.8 – 20 K). While a small number of dedicated RF test facilities exist worldwide, many are limited by a slow sample turnover. To address this, a core element of the programme has been the development of a dedicated RF characterisation facility, designed primarily to deliver quick sample measurements. Its successful operation shows that high throughput RF characterisation is critical for accelerating thin film SRF development and guiding future cavity fabrication.
