An automatic frequency control system based on MicroTCA

Abstract Background: High quality electronic beam is the key to produce high quality synchrotron radiation or free-electron laser (FEL). Microwave electronic LINAC plays the role of injector, whose performance influences the quality of electronic beam deeply. Purpose: In order to minimize the noise interference (temperature, microphonics, etc), we develop a universal, robust, efficient and extendible Low Level Radio Frequency (LLRF) control system, in which automatic frequency control (AFC) function is already implanted and more functions will be embedded in the future. Methods: This system, based on MicroTCA, adopts Experimental Physics and Industrial Control System (EPICS) structures, and develops in C/C++. The core algorithms are Proportion-Integral-Differential (PID) and Least-Squares method. Results: Two different ways of AFC were realized and the system was tested on Sirius-LINAC test facility. Conclusion: The result shows that the cavity is well tuned when the AFC system is on, and obvious differences are found. This system will be optimized and enlarged in the future. (authors)