A bunch-by-bunch polarization switching scheme for high-repetition-rate hard X-ray FELs
A bunch-by-bunch polarization switching scheme for high-repetition-rate hard X-ray FELs
Gao, Dr. Zhangfeng LIU, Dr. Yongfang 1WANG, Mrs. Ruiping Wen, Miss YongMei Tang, Dr. Qisheng Liu, Dr. Tao Gu, Dr. Duan Deng, Dr. Haixiao 邓海啸2
作者信息
- 1. Shanghai Advanced Research Institute Chinese Academy of Sciences
- 2. Shanghai Advanced Research Institute
- 折叠
摘要
Over the past two decades, rapid advancement of free electron laser (FEL) technology has effectively addressed extensive research requirements. Currently, nearly all FEL facilities generate high-quality radiation with controllable polarization via devices like APPLE-type undulators or DELTA undulators. However, elliptically polarized undulators alone cannot achieve hertz-level or above polarization switching, which complicates experiments such as time-resolved circular dichroism spectroscopy. To solve this, based on the FEL-II beamline of the Shanghai High Repetition Rate X-ray FEL and Extreme Light Facility, this study proposes integrating a custom-designed bunch-by-bunch phase shifter into APPLE-type undulator arrays (following crossed-planar undulator design logic). We analyzed factors influencing post-superposition radiation polarization under ideal Gaussian mode propagation, determined optimal parameters for both fast polarization switching performance and fixed-polarization radiation quality, conducted validation via start-to-end simulations, and presented the phase shifter’s detailed design. Results show high-frequency undulator-section polarization switching is achievable with only slight polarization purity trade-off, and the scheme is universally applicable to FEL facilities with high-energy electron beam.
Abstract
Over the past two decades, rapid advancement of free electron laser (FEL) technology has effectively addressed extensive research requirements. Currently, nearly all FEL facilities generate high-quality radiation with controllable polarization via devices like APPLE-type undulators or DELTA undulators. However, elliptically polarized undulators alone cannot achieve hertz-level or above polarization switching, which complicates experiments such as time-resolved circular dichroism spectroscopy. To solve this, based on the FEL-II beamline of the Shanghai High Repetition Rate X-ray FEL and Extreme Light Facility, this study proposes integrating a custom-designed bunch-by-bunch phase shifter into APPLE-type undulator arrays (following crossed-planar undulator design logic). We analyzed factors influencing post-superposition radiation polarization under ideal Gaussian mode propagation, determined optimal parameters for both fast polarization switching performance and fixed-polarization radiation quality, conducted validation via start-to-end simulations, and presented the phase shifters detailed design. Results show high-frequency undulator-section polarization switching is achievable with only slight polarization purity trade-off, and the scheme is universally applicable to FEL facilities with high-energy electron beam.关键词
Free electron laser/Fast polarization switch/Bunch-by-bunch phase shifter/Crossed-planar undulators引用本文复制引用
Gao, Dr. Zhangfeng,LIU, Dr. Yongfang,WANG, Mrs. Ruiping,Wen, Miss YongMei,Tang, Dr. Qisheng,Liu, Dr. Tao,Gu, Dr. Duan,Deng, Dr. Haixiao 邓海啸.A bunch-by-bunch polarization switching scheme for high-repetition-rate hard X-ray FELs[EB/OL].(2026-09-21)[2026-09-26].https://chinaxiv.org/abs/202609.00295.学科分类
光电子技术
