Design of a 324 MHz Double-Spoke Cavity at CSNS

The design study of a 324 MHz double-spoke cavity is presented in this article. The geometric parameters are optimized to get reasonable RF properties (e.g., low <italic>E</italic><sub>p</sub>/<italic>E</italic><sub>acc</sub>, low <italic>B</italic><sub>p</sub>/<italic>E</italic><sub>acc</sub>, and high <italic>R</italic>/<italic>Q</italic>). Then, the end cap and the spoke base of the cavity are deliberately optimized to minimize multipacting for the design gradient. Furthermore, the mechanical design is optimized to reduce the Lorentz coefficient and the frequency sensitivity of helium pressure fluctuation. In view of the pulsed operation characteristics of the cavity, the RF pulse spectrum and the corresponding amplitude of each spectrum are evaluated. Finally, the modal analysis is performed by the ANSYS software, and the first six modes are classified.