Tuning methods for the 805 MHz side-coupled cavities in the Fermilab linac upgrade

The fabrication and tuning of Side-Coupled Accelerator Structures (SCS) are strongly interrelated. Consideration of mechanical tolerances and fabrication sequences can reduce tuning steps that require repeated machining. With available CNC machines and numerical calculation programs, it is possible to machine cavities to a calculated shape. Accelerating cells are tuned by control of the depth of coupling slots rather than trimming the nose of accelerating cells. Predicting the correct frequency off-sets to use at each manufacturing stage produces a brazed structure of proper couplig with a minimum amount of tuning. 2 refs., 1 fig.