Nuclear Science and Techniques ›› 2019, Vol. 42 ›› Issue (1): 10101-010101.doi: 10.11889/j.0253-3219.2019.hjs.42.010101

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Front-end frequency conversion module design for harmonic RF system in SSRF

Pengpeng GONG1,2,3,Yubin ZHAO1,3,Hongtao HOU1,3,Zhigang ZHANG1,3,Xiang ZHENG1,3,Kai XU1,3,Qiang CHANG1,3,Yangyang XIA1,2,3,Jianfei LIU1,3()   

  1. 1. Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
    2. University of Chinese Academy of Sciences, Beijing 100049, China
    3. Shanghai Key Laboratory of Cryogenics & Superconducting RF Technology, Shanghai 201800, China
  • Received:2018-08-24 Revised:2018-09-18 Online:2019-01-10 Published:2019-01-25
  • Contact: Jianfei LIU
  • Supported by:
    Supported by National Natural Science Foundation of China (No.11335014)

Abstract: Background

Shanghai synchrotron radiation facility (SSRF) is the third generation synchrotron radiation source. In the phase II project, the third harmonic superconducting cavity will be used to improve Touschek lifetime by lengthening the bunch.


This study aims to achieve the tuning control of the harmonic radio frequency (RF) system by frequency reduction of the 1.5 GHz signal from harmonic cavity for signal sampling in the control system.


First of all, three kinds of frequency conversion schemes were introduced. Then outcomes of reducing 1.5 GHz RF signal to 31.25 MHz intermediate frequency (IF) signal by using these three schemes were performed. Finally the characteristics of each scheme and the factors affecting the results of down conversion are analyzed.


The test results shown that three down conversion schemes has good linearity in different dynamic range and met control system specifications. The optimal scheme based on frequency multiplier achieved best performance of linear dynamic range greater than 70 dB and lowest phase noise of IF signal.


A down conversion scheme with frequency multiplier will be applied in the harmonic RF control system.

Key words: Third harmonic cavity, Down conversion, Low level radio frequency (LLRF), Touschek lifetime

CLC Number: 

  • TL503.2