Sub-picosecond electron bunch length measurement using coherent transition radiation at SXFEL

  • Yu Bian
  • Wen-Yan Zhang
  • Bo Liu
  • Dong Wang


Longitudinal electron bunch length plays a significant role in single-pass free-electron lasers (FEL), as the high-gain FEL process depends strongly on the high peak current of electron bunches. Longitudinal electron bunch length was measured by detecting the interferogram of coherent transition radiation generated by electron bunches using a THz interferometer and a Golay cell (spectral range 0.02–20 THz) at Shanghai X-ray free-electron laser. The detailed process of measurement and data analysis are discussed herein. Furthermore, the electron bunch length was estimated based on the dispersive strength \( R_{56} \) of the bunch compressor and the energy spread \( \delta \) of electron bunches, which were obtained via experiments. The comparison showed that the measured bunch length was consistent with the estimated bunch length.


Electron bunch length THz interferometer Coherent transition radiation Beam diagnostics 



We thank Dr. Jin-Feng Yang and Dao Xiang for their useful discussions and encouragement.


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Copyright information

© Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Chinese Nuclear Society, Science Press China and Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  1. 1.Shanghai Institute of Applied PhysicsChinese Academy of SciencesShanghaiChina
  2. 2.University of Chinese Academy of SciencesBeijingChina

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