Design of 325 MHz Single and Triple Spoke Resonators at FNAL

The proposed 8-GeV driver at FNAL is based on approximately 400 independently phased superconducting resonators. In this paper the design of 325 MHz spoke resonators, two single spoke resonators (beta = 0.21 and beta = 0.4) and a triple spoke resonator (beta = 0.62), for the high intensity neutrino source (HINS) front end is presented. We describe the optimization of the spoke resonator geometry, the goal being to minimize the E PEAK /E ACC and B PEAK /E ACC ratios. We report on the coupled ANSYS-MWS analysis on the resonator mechanical properties and power coupler RF design. The current status of mechanical design and slow tuning mechanism are also presented.