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Description
An accelerator system employing RF cavities requires the use of a stable RF source, and some require multiple frequencies, either for acceleration or for bunching. These frequencies must be synchronized in phase in order to work properly. These are usually derived from a single low phase noise master reference frequency source. A fixed frequency oscillator or a variable frequency oscillator such as a frequency synthesizer are commonly used as the master frequency oscillator. Other frequencies are generated using this master source either through frequency multipliers or phase-locked loops. Phase noise is a crucial performance index of these sources, because once generated, phase noise will be persistant and cannot be corrected. Other active devices such as RF amplifiers, frequency up/down converters will contribute to the additive phase noise. The various aspects including merits and limitations of a master source, frequency multipliers and PLLs, together with the effect on beam quality on different types of resonant cavities, are investigated.
