Sensitivity study of 650 MHz five cell SRF cavity under Lorentz force

Mechanical design and analysis of a 65a MHz (β = 0.61), 5 cell superconducting radio frequency cavity is in progress at VECC under the Indian Institutions- Fermilab collaboration (IIFC). The Lorentz force generated on the cavity walls owing to the combined effect of electric and magnetic field, results in structural deformation of the cavity. Consequently, accelerating mode frequency of the cavity gets shifted. In this paper, a study has been performed to estimate the change in frequency of an un-stiffened cavity due to Lorentz force. Coupled sequential structural and high frequency electromagnetic analysis have been carried out for different structural boundary conditions of the cavity to obtain the static Lorentz force detuning coefficient. Study of finite element mesh sensitivity on the simulation results has also been presented. (author)