Mechanical properties of 3+1/2 cavity of PKU photo-injector

The mechanical properties of the main part of PKU photo-injector (3+1/2 cavity) are introduced. By optimizing the number and position of the stiff rings of the cavity with ANSYS and SUPERFISH code, the Lorentz force detuning problem when the cavity worked at pulsed mode and the “flat” field profile problem when the cavity was tuned at low temperature were solved. Besides, a tuner with a room temperature motor and a gear box for the cavity to work at the right frequency under 2 K circumstance was designed.