微波零相位法测量超导加速器ps级电子束纵向长度
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摘要
本文基于微波零相位法,将中国工程物理研究院太赫兹自由电子激光(CTFEL)2×4-cell超导加速器的下游腔作为零相位腔,测量了上游腔增能后的电子束纵向长度,并通过束流动力学模拟证明,当两个超导腔正常工作时,上游腔出口处的电子束纵向长度与下游腔出口处的接近。实验结果表明,CTFEL 2×4-cell超导加速器能实现半高宽小于6.8 ps的电子束,满足装置出光要求。
In this paper, the electron beam length of China Academy of Engineering Physics THz Free Electron Laser(CTFEL) was measured by the means of the RF zero-phasing method. The downstream cavity of the 2×4-cell superconducting accelerator was used as the zero-phasing cavity. Then the electron beam length accelerated by the first superconducting cavity was measured, which was proved to be almost the same as the one at downstream cavity when the two cavities were both working, by the means of dynamics simulation. The measurement results show that the FWHM of electron beam is less than 6.8 ps after the acceleration of the 2×4-cell superconducting accelerator, which meets the requirement of the facility.
In this paper, the electron beam length of China Academy of Engineering Physics THz Free Electron Laser(CTFEL) was measured by the means of the RF zero-phasing method. The downstream cavity of the 2×4-cell superconducting accelerator was used as the zero-phasing cavity. Then the electron beam length accelerated by the first superconducting cavity was measured, which was proved to be almost the same as the one at downstream cavity when the two cavities were both working, by the means of dynamics simulation. The measurement results show that the FWHM of electron beam is less than 6.8 ps after the acceleration of the 2×4-cell superconducting accelerator, which meets the requirement of the facility.
引文
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[2] 黎明,杨兴繁,许州,等.CAEP太赫兹自由电子激光首次饱和出光[J].强激光与粒子束,2017,29(10):29100101.LI Ming,YANG Xingfan,XU Zhou,et al.First lasing of CAEP THZ free electron laser[J].High Power Laser and Particle Beams,2017,29(10):29100101(in Chinese).
[3] 黎明,杨兴繁,许州,等.太赫兹自由电子激光的受激饱和实验[J].物理学报,2018,67(8):084102.LI Ming,YANG Xingfan,XU Zhou,et al.Experimental study on the stimulated saturation of terahertz free electron laser[J].Acta Physica Sinica,2018,67(8):084102(in Chinese).
[4] FENG Chao,DENG Haixiao.Review of fully coherent free-electron lasers[J].Nuclear Science and Techniques,2018,29:160.
[5] 谢家麟,庄杰佳,钟世材,等.北京自由电子激光装置的设计研究[J].强激光与粒子束,1989,1(4):289-305.XIE Jialing,ZHUANG Jiejia,ZHONG Shicai,et al.Design study of Beijing free electron laser facility[J].High Power Laser and Particle Beams,1989,1(4):289-305(in Chinese).
[6] 惠中锡,杨震华.自由电子激光[M].北京:国防工业出版社,1995.
[7] DATTOLI G,LETARDI T,RENIERI A,et al.Lawson-Penner limit and single passage free electron lasers performances[J].IEEE Journal of Quantum Electronics,2003,20(6):637-646.
[8] DOU Yuhuan,SHU Xiaojian,YANG Xinfan,et al.Optical resonator optimization of CAEP THz-FEL[C]∥40th International Conference of IRMMW-THz.Hong Kong:IEEE,2015.
[9] KREJCIK P.Short bunch beam diagnostics[C]//AIP Conference Proceedings.Italy:[s.n.],2004.
[10] WANG D X,KRAFFT G A,SINCLAIR C K.Measurement of femtosecond electron bunches using a RF zero-phasing method[J].Physical Review E,2008,57(2):2 283-2 286.
[11] GRAVES W,CARR G,MAURO D L,et al.Ultrashort electron bunch length measurements at DUVFEL[C]∥Proceedings of PAC01.USA:IEEE,2001.
[12] HUANG Z,SHAFTAN T.Impact of beam energy modulation on RF zero-phasing microbunch measurements[J].Nuclear Instruments and Methods in Physics Research A,2004,528(1):345-349.
[13] FL?TTMANN K.Astra:A space charge tracking algorithm[R/OL].[2017-03-01].http://www.desy.de/～mpyflo/Astra_manual/Astra-Manual_V3.2.pdf.
[14] LIU Wenxin,WU Dai,WANG Yingxin,et al.Terahertz frequency measurement of far infrared laser with an improvement of martin-puplett interferometer[J].Nuclear Instruments and Methods in Physics Research A,2010,614(2):313-318.
[15] 吴岱,刘文鑫,唐传祥,等.用于频域方法测量超短电子束纵向分布的Kramers-Kr?nig变换研究[J].物理学报,2011,60(8):082901.WU Dai,LIU Wenxin,TANG Chuanxiang,et al.Research of Kramers-Kr?nig relationship for reconstruction of ultrashort electron longitudinal bunch profile by means of frequency domain measurements[J].Acta Physica Sinica,2011,60(8):082901(in Chinese).
[16] 向导.高亮度电子束发射度、束长和束斑的先进测量方法研究[D].北京:清华大学,2008.