Design and testing of the bunch-by-bunch beam transverse feedback electronics for SSRF

Abstract

Shanghai Synchrotron Radiation Facility (SSRF), is one of the third-generation high-beam current (3.5GeV) synchrotron light sources. In the storage ring of SSRF, multi-bunch instabilities would increase beam emittance and energy spread, which degrade beam quality and even cause beam loss. To address the above issues, a Transverse Feedback System is indispensable for SSRF, in which the key component is the bunch-by-bunch transverse feedback electronics. The whole feedback system consists of five main parts: BPM, RF front-end, signal processor, RF amplifier, and vertical/horizontal transverse kickers. The dissertation focuses on the signal processor we design, which is the main part of the feedback electronics. We conducted initial testing on the signal processor to evaluate its performance and function. The typical frequency spectrums analysis (with input frequency of around 100 MHz) of the ADC output signals indicates that the SINAD (Signal-to-Noise and Distortion Ratio) is 63.69 dB and the ENOB (Effective Number of Bit) is 10.3 bit. The test results of ENOB with different input frequency indicate that it is better than 9.5 bit in the input frequency range up to 300 MHz, which is good enough for the application. Besides, the test results of the hardware and the results of the MATLAB model concord well with each other, which means that we have achieved the functionality as expected.