C波段光阴极电子枪驱动激光整形研究

姜世民; 陆志军; 刘星光; 李晓

doi:10.11884/HPLPB202436.240162

C波段光阴极电子枪驱动激光整形研究

doi: 10.11884/HPLPB202436.240162

姜世民^{1, 2,},
陆志军^{1, 2},
刘星光^{1, 2},
李晓^{1, 2}

1.
中国科学院高能物理研究所，北京 100049
2.
散裂中子源科学中心，广东东莞 523803

基金项目: 中国科学院高能物理研究所谢家麟基金项目(E4546JU2)

详细信息

作者简介:
姜世民，jiangsm@ihep.ac.cn

中图分类号: O463⁺.1；O434
计量
- 文章访问数: 26
- HTML全文浏览量: 21
- PDF下载量: 2
- 被引次数: 0
出版历程
- 收稿日期: 2024-05-14
- 修回日期: 2024-09-09
- 录用日期: 2024-09-09
- 网络出版日期: 2024-09-19

Study of drive laser shaping system for C-band photocathode RF gun

Jiang Shimin^{1, 2
,},
Lu Zhijun^{1, 2},
Liu Xingguang^{1, 2},
Li Xiao^{1, 2}

1.
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
2.
Spallation Neutron Source Science Center, Dongguan 523803, China

摘要

摘要: 在光阴极电子枪系统当中，驱动激光的时空整形是实现束流低发射度的关键之一。基于南方光源预研项目C波段光阴极电子枪测试平台，介绍了驱动激光系统的布局与测试相关内容。测试平台于国内首次采用初始RMS脉冲长度为160 fs的266 nm激光作为驱动激光，利用双折射晶体的脉冲时间延迟完成对激光脉冲纵向时间整形，并配备多个孔径的可调光阑实现对束流的横向尺寸的调节。经过整形，激光平台可以提供纵向RMS长度为160 fs、420 fs的高斯脉冲激光与半高全宽为5 ps的平顶分布脉冲激光，根据激光测试结果，简要分析了不同脉冲分布对于束流发射度演化以及脉冲分布的影响，不仅为后续光阴极电子枪束流调试提供了指导，并对初始脉冲分布对空间电荷力的影响实现更加深入的研究提供了支持。
- 光阴极电子枪 /
- C波段 /
- 激光整形 /
- 双折射晶体 /
- 发射度
Abstract: In photocathode electron gun system, the space-time shaping of the laser is one of the important parts to achieve low emittance of the beam. Based on the C-band photocathode electron gun test platform of the Southern Advanced Photon Source pre-research project, the layout and testing of the drive laser system are introduced in this paper. A 266 nm laser with an initial RMS pulse length of 160 fs is first used as the driving laser in the test platform in China. The longitudinal time of the laser pulse is shaped by the pulse time delay of the birefringent crystal, and the transverse beam is realized by an adjustable diaphragm with multiple apertures. After shaping, the laser platform can provide a Gaussian pulse with a longitudinal RMS length of 160 fs and 420 fs, and a flat-top distributed pulse laser with FWHM of 5 ps. According to the laser test results, the influence of different pulse distributions on beam emittance evolution and pulse distribution is briefly analyzed in this paper. It provides not only a guidance for the photocathode electron gun commissioning, but also support for further research on the effect of initial pulse distribution on space charge force.
- photocathode RF gun /
- C-band /
- laser shaping /
- birefringent crystal /
- emittance

HTML全文

图 1 驱动激光系统布局图

Figure 1. Layout of the drive laser system

下载: 全尺寸图片幻灯片

图 2 激光脉冲纵向分布整形

Figure 2. Longitudinal distribution shaping of the laser pulse

下载: 全尺寸图片幻灯片

图 3 电子枪平台的概念布局图

Figure 3. Layout of photocathode electron gun test platform

下载: 全尺寸图片幻灯片

图 4 电荷量为10 pC时，三种纵向束流分布下的束流发射度演化以及在1.1 m处y-z平面上的束流分布

Figure 4. Evolution of beam emittance and the beam distribution in the y-z plane at 1.1 m in three longitudinal beam distributions for 10 pC bunch charge

下载: 全尺寸图片幻灯片

图 5 电荷量为100 pC时，三种纵向束流分布下的束流发射度演化以及在1.1 m处y-z平面上的束流分布

Figure 5. Evolution of beam emittance and the beam distribution in the y-z plane at 1.1 m in three longitudinal beam distributions for 100 pC bunch charge

下载: 全尺寸图片幻灯片

表 1 激光系统参数要求

Table 1. Parameters required for drive laser system

wavelength/nm	pulse energy in cathode/µJ	RMS radius/mm	FWHM/ps	longitudinal distribution
266	≥150	≤0.15	≤5	flat-top

下载: 导出CSV

表 2 激光器参数

Table 2. Parameters of drive laser

element	wavelength/nm	pulse RMS width/fs	repetition rate/Hz	pulse energy/mJ
oscillator	800	100	79.33×10⁶	15×10⁻⁶
amplifier	800	−	1～100	13
third harmonic generator	266	160	1～100	2

下载: 导出CSV

表 3 α-BBO晶体的参数

Table 3. Parameters of α-BBO

No.	wavelength/nm	L/mm	time delay/ps
1	266	0.71	0.6
2	266	1.42	1.2
3	266	2.84	2.4

下载: 导出CSV

参考文献(18)

[1]	Rao T S, Dowell D H. An engineering guide to photoinjectors(2013)[M/OL]. Available at:. https://arxiv.org/abs/1403.7539.
[2]	Li Cheng, Wang Wenxing, Zhang Haoran, et al. Few-femtosecond MeV electron bunches for ultrafast electron diffraction[J]. Physical Review Applied, 2022, 17: 064012. doi: 10.1103/PhysRevApplied.17.064012
[3]	Ackermann W, Asova G, Ayvazyan V, et al. Operation of a free-electron laser from the extreme ultraviolet to the water window[J]. Nature Photonics, 2007, 1(6): 336-342. doi: 10.1038/nphoton.2007.76
[4]	Schaap B H, De Vos T D C, Smorenburg P W, et al. Photon yield of superradiant inverse Compton scattering from microbunched electrons[J]. New Journal of Physics, 2022, 24: 033040. doi: 10.1088/1367-2630/ac59eb
[5]	Zheng Lianmin, Du Yingchao, Zhang Zhe, et al. Development of S-band photocathode RF guns at Tsinghua University[J]. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2016, 834: 98-107.
[6]	Xu Hanxun, Shi Jiaru, Du Yingchao, et al. Development of an L-band photocathode RF gun at Tsinghua University[J]. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2021, 985: 164675. doi: 10.1016/j.nima.2020.164675
[7]	Fang Wencheng, Gu Qiang, Sheng Xing, et al. Design, fabrication and first beam tests of the C-band RF acceleration unit at SINAP[J]. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2016, 823: 91-97.
[8]	Limborg-Deprey C, Adolphsen C, McCormick D, et al. Performance of a first generation X-band photoelectron RF gun[J]. Physical Review Accelerators and Beams, 2016, 19: 053401. doi: 10.1103/PhysRevAccelBeams.19.053401
[9]	Bettoni S, Divall M C, Ganter R, et al. Impact of laser stacking and photocathode materials on microbunching stability in photoinjectors[J]. Physical Review Accelerators and Beams, 2020, 23: 024401. doi: 10.1103/PhysRevAccelBeams.23.024401
[10]	Limborg-Deprey C, Bolton P R. Optimum electron distributions for space charge dominated beams in photoinjectors[J]. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2006, 557(1): 106-116.
[11]	Zhou Feng, Brachmann A, Emma P, et al. Impact of the spatial laser distribution on photocathode gun operation[J]. Physical Review Accelerators and Beams, 2012, 15: 090701. doi: 10.1103/PhysRevSTAB.15.090701
[12]	李成, 汪文星, 李伟伟, 等. 光阴极微波电子枪驱动激光整形与传输系统[J]. 强激光与粒子束, 2021, 33:094002 doi: 10.11884/HPLPB202133.210091 Li Cheng, Wang Wenxing, Li Weiwei, et al. Drive laser shaping and transport system for photocathode RF gun[J]. High Power Laser and Particle Beams, 2021, 33: 094002 doi: 10.11884/HPLPB202133.210091
[13]	Rublack T, Khojoyan M, Krasilnikov M, et al. Development of a quasi 3-D ellipsoidal photo cathode laser system for PITZ[C]//Proceedings of the 5th International Particle Accelerator Conference (IPAC 2014). 2014: 3.
[14]	Mironov S Y, Potemkin A K, Gacheva E I, et al. Shaping of cylindrical and 3D ellipsoidal beams for electron photoinjector laser drivers[J]. Applied Optics, 2016, 55(7): 1630-1635. doi: 10.1364/AO.55.001630
[15]	Musumeci P, Moody J T, England R J, et al. Experimental generation and characterization of uniformly filled ellipsoidal electron-beam distributions[J]. Physical Review Letters, 2008, 100: 244801. doi: 10.1103/PhysRevLett.100.244801
[16]	Liu Xingguang. A C-band test platform for the development of RF photo cathode and high gradient accelerating structures[C]//Proceedings of the 14th International Particle Accelerator Conference. 2023: 1995-1998.
[17]	Liu X G, Jiao Y, Li B B, et al. Preliminary design of the full energy Linac injector for the southern advanced photon source[C]//Proceedings of the 12th International Particle Accelerator Conference. 2021.
[18]	Floettmann K. ASTRA: a space charge tracking algorithm version 3.2[M]. Hamburg: DESY, 2017.