Phase scan signature matching for linac tuning

A conceptually simple method for tuning linac tanks has been tested on the Alvarez linac at Fermilab. Phases of beam-induced signals in stripline detectors are measured as tank phase is scanned over approximately 360 degrees. The stripline detectors are located downstream of the tank being tuned. The phase-scan curves have unique signatures that depend upon input beta and electric field. By matching theoretical curves of beam phase versus tank phase to measured curves, the important tuning parameters are determined. The tank parameters which are varied during curve matching include field amplitude, input beta, and relative tank-phase offset of the phase-scan curves. The actual phase of the tank fields relative to the design phase is found by noting the position of the actual tank phase along the phase-scan curve, once a curve match is obtained