The effects of low RF modulation frequencies on the longitudinal beam motion at the Pohang light source

Abstract

RF noises in the storage-ring RF system may affect electron bunches directly. They adversely affect various beam properties, such as the bunch shape, the bunch length, the centroid motion, the oscillation amplitude, etc. An external function generator was used to modulate the RF phase in order to simulate the high peak RF noises; then, the bunch oscillation, the bunch length, the radiation fluctuation from the streak camera image, and the RF spectrum were measured. From the measurement results, the bunch lengthening coefficient and the oscillation amplitude coefficient were determined.