Multiphysics study on the higher harmonic RF cavity for the Iranian Light Source Facility’s storage ring

Higher harmonic cavities are widely used in low-emittance and high-current synchrotron storage rings to increase the stored beam's lifetime and eliminate the coupled bunch instabilities. These parameters have an essential effect on the quality of synchrotron radiation and the machine's stability. Higher harmonic cavities of the Iranian light source facility are passive, capacitive-loaded structures designed to operate at 300 MHz. These cavities can operate in the beam current range of 50-400 mA. This article comprehensively discusses analytical calculations and simulations of beam dynamics, electromagnetic, thermomechanical, and vacuum aspects of the Iranian Light Source Facility's higher harmonic cavities. The engineering drawings are finalized after many technical discussions according to the presented results, and the fabrication process of the higher harmonic cavity has been started accordingly. The low-power RF measurement results of the first developed prototype are reported in the final section.