Improving the stability of pulse superconducting radio frequency cavities by the construction of an Al-Nb double layer structure

Superconducting Radio Frequency technologies are widely employed in particle accelerators to explore the frontiers of science. Pure niobium cavity with 2.8-4mm thickness is the traditional technology of a compromise between the thermal conduction and mechanic stability. To meet the requirements of the higher stability of accelerators such as ADS linac, high intensity pulse linac, a solution for enhancing the stability of superconducting cavities by the Al-Nb double layer structure is proposed while maintaining enough heat transfer capacity. In this work, a 3.9GHz single cell Al-Nb elliptical cavity was fabricated to validate this proposal. During the vertical testing, the cavity shows a significant enhancement in the mechanical stability with LFD coefficient reduction by 88% compared to the pure Nb cavity and Q0 value is kept at the same level. Additionally, the basic parameters of Al-Nb composite material were tested and reported as well.