Fast Automatic Phase and Amplitude Control of High-Power RF Systems

Recent progress in the design and testing of the fast feedback rf control system being developed for the Los Alamos Meson Physics Facility (LAMPF) proton linac is reviewed. Closed-loop rf phase control with correction bandwidths greater than 200 kHz is demonstrated using a coaxitron power amplifier driving a full-scale accelerator structure. Proposed experimental studies to determine control characteristics, synthesize closedloop amplitude control systems, and study phase-amplitude interactions in 1.25-MW, 6% s duty factor klystron, triode, and crossed-field amplifier systems are outlined. Ectremely phase-stable frequency sources have been developed to supply reference signals at 201.25 MHz and 805 MHz. The design and testing techniques used to verify phase stability and mutual coherence of the harmonically related outputs are sumnarized.