Design Guidelines of a Double-Gap Microwave Rebuncher Cavity for a 400 MHz, 2.5 MeV Energy Light Ion Accelerator with Lower Gap Voltage and Field

A detailed electromagnetic model of a double-gap microwave rebuncher cavity proposed for 400-MHz, 2.5 MeV energy of the front end section in 1 GeV energy H- ion linear accelerator, is presented and validated by extensive simulations. This design is intended to decrease both the utilized gap voltage and peak electric field of the rebunching cavity, henceforth may decrease X-ray radiation. A low cost 1/2 scaled aluminum cavity double gap model was built and tested for model validation. Mode frequencies and quality factors of the model were measured and compared to simulation. Additionally, bead perturbation method was used to measure the para-axial electric field. Simulation of the single and double gap cavities were compared to measurements and were in very good agreement. Subsequently, design guidelines have been developed to design the double gap rebuncher, optimize its gap size for lower electric fields and reduced X-ray radiation.