Second Harmonic Cavity Design for Project-X Main Injector

In order to accelerate the proposed beam intensity for Project X at FNAL, the current Main Injector (MI) RF system will be required upgrading the 53 MHz first harmonic RF system and adding 106 MHz second harmonic cavities to meet the MI requirements for Project X. The new first harmonic RF cavity design is a single gap quarter wave coaxial resonator with a perpendicular biased ferrite tuner. The second harmonic RF cavity baseline design is similar to the fundamental one and scaled down from it. The RF simulations and shape optimizations on the first and second harmonic cavities are carried out to obtain the optimal performance which meets Project X requirements. The results are discussed and presented in this paper.