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摘要: 为满足合肥先进光源对高品质注入束流的要求，合肥先进光源预研项目研制了一套光阴极微波电子枪系统作为注入器电子源。为降低空间电荷效应引起的束流发射度增长，对驱动激光整形及传输系统进行了理论和实验研究。通过双折射晶体的脉冲时间整形以及采用光阑高斯截断的空间整形，得到了近似均匀分布的激光脉冲。像传递激光传输光路，实现了光阴极表面激光位置的高稳定性。实验结果显示，光阴极表面的激光位置抖动小于4 µm，激光性能满足实验要求。Abstract: To meet the requirements of Hefei Advanced Light Facility (HALF) for high quality injection beam, a photocathode RF gun is developed as the electron source of the injector in the R&D project. To obtaining an electron beam with high qualities, it is necessary to carry out experimental research on drive laser shaping and transport system. For suppressing the beam emittance growth caused by space charge force, the temporal pulse shape is modified by using birefringent crystals, while an aperture is used for spatial pulse shaping. An optical image transport system is designed to achieve high stability of the laser beam position on the photocathode. Detailed design of the optical system is presented in this paper. The experimental result shows that a quasi uniform distribution in the three-dimensional space of laser pulse is obtained, and the laser beam position jitter on the photocathode is less than 4 µm. The performance of the laser pulse meets the experiment requirements.
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Key words:
- photocathode RF gun /
- laser shaping /
- birefringent crystals /
- transport system /
- emittance
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Figure 5. Measured transverse distributions (upper) and horizontal cuts (lower) of laser pulse at different positions around the nominal imaging plane. From left to right, the distances to the nominal imaging plane are −5 cm, 0 cm and 5 cm.
Table 1. Laser parameters
element wavelength/nm pulse width/fs repetition rate/Hz pulse energy/nJ oscillator 800 42 79.33×106 9 amplifier 800 103 1−100 13×106 third harmonic generator 266.7 1.5×103 1−100 2×106 
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[1] Akre R, Dowell D, Emma P, et al. Commissioning the linac coherent light source injector[J]. Physical Review Special Topics-Accelerators and Beams, 2008, 11: 030703. doi: 10.1103/PhysRevSTAB.11.030703 [2] Zhu Pengfei, Zhu Y, Hidaka Y, et al. Femtosecond time-resolved MeV electron diffraction[J]. New Journal of Physics, 2015, 17: 063004. doi: 10.1088/1367-2630/17/6/063004 [3] Xiang D, Fu F, Zhang J, et al. Accelerator-based single-shot ultrafast transmission electron microscope with picosecond temporal resolution and nanometer spatial resolution[J]. Nuclear Instruments and Methods in Physics Research Section A:Accelerators, Spectrometers, Detectors and Associated Equipment, 2014, 759: 74-82. [4] Yang Jinfeng, Kondoh T, Kozawa T, et al. Pulse radiolysis based on a femtosecond electron beam and a femtosecond laser light with double-pulse injection technique[J]. Radiation Physics and Chemistry, 2006, 75(9): 1034-1040. doi: 10.1016/j.radphyschem.2005.09.016 [5] Chen Han, Yan Lixin, Tian Qili, et al. Commissioning the photoinjector of a gamma-ray light source[J]. Physical Review Accelerators and Beams, 2019, 22: 053403. doi: 10.1103/PhysRevAccelBeams.22.053403 [6] Kim K J. RF and space-charge effects in laser-driven RF electron guns[J]. Nuclear Instruments and Methods in Physics Research Section A:Accelerators, Spectrometers, Detectors and Associated Equipment, 1989, 275(2): 201-218. doi: 10.1016/0168-9002(89)90688-8 [7] Serafini L, Rosenzweig J B. Envelope analysis of intense relativistic quasilaminar beams in rf photoinjectors: mA theory of emittance compensation[J]. Physical Review E, 1997, 55(6): 7565-7590. doi: 10.1103/PhysRevE.55.7565 [8] Schwarz J, Rambo P K, Smith I C, et al. Simple temporal pulse shaping using two Pockels cells[J]. Optical Engineering, 2005, 44: 094203. doi: 10.1117/1.2052709 [9] Sharma A K, Patidar R K, Raghuramaiah M, et al. Simple electro-optic technique to generate temporally flat-top laser pulses[J]. Optics Communications, 2011, 284(19): 4596-4600. doi: 10.1016/j.optcom.2011.05.061 [10] Skeldon M D. Optical pulse-shaping system based on an electro-optic modulator driven by an aperture-coupled-stripline electrical-waveform generator[J]. Journal of the Optical Society of America B, 2002, 19(10): 2423-2426. doi: 10.1364/JOSAB.19.002423 [11] Field J J, Durfee III C G, Squier J A, et al. Quartic-phase-limited grism-based ultrashort pulse shaper[J]. Optics Letters, 2007, 32(21): 3101-3103. doi: 10.1364/OL.32.003101 [12] Weiner A M. Femtosecond pulse shaping using spatial light modulators[J]. Review of Scientific Instruments, 2000, 71(5): 1929-1960. doi: 10.1063/1.1150614 [13] Weiner A M. Ultrafast optical pulse shaping: a tutorial review[J]. Optics Communications, 2011, 284(15): 3669-3692. doi: 10.1016/j.optcom.2011.03.084 [14] Loos H, Dowell D, Gilevich S, et al. Temporal E-beam shaping in an S-band accelerator[C]//Proceedings of the 2005 Particle Accelerator Conference. 2005: 642-644. [15] Vicario C, Ghigo A, Cialdi S, et al. Laser temporal pulse shaping experiment for SPARC photoinjector[R]. CARE-Conf-04-030-PHIN, 2004. [16] Park Y, Asghari M H, Ahn T J, et al. Transform-limited picosecond pulse shaping based on temporal coherence synthesization[J]. Optics Express, 2007, 15(15): 9584-9599. doi: 10.1364/OE.15.009584 [17] Wang X T, Feng L, Lan T, et al. Drive laser temporal shaping techniques for Shanghai soft X-ray free electron laser[C]//39th International Free Electron Laser Conference. 2019: 466-468. [18] Sharma A K, Tsang T, Rao T. Theoretical and experimental study of passive spatiotemporal shaping of picosecond laser pulses[J]. Physical Review Special Topics-Accelerators and Beams, 2009, 12: 033501. doi: 10.1103/PhysRevSTAB.12.033501 [19] Wang Dong, Yan Lixin, Huang Wenhui. UV Pulse shaping with α-BBO crystals for the photocathode RF gun[C]//Proceedings of the 7th International Particle Accelerator Conference. 2016: 4079-4081. [20] Laskin A, Laskin V. Imaging techniques with refractive beam shaping optics[C]//Proceedings of SPIE 8490, Laser Beam Shaping XIII. 2012: 84900J. [21] Laskin A, Laskin V. Beam shaping in high-power laser systems with using refractive beam shapers[C]//Proceedings of SPIE 8433, Laser Sources and Applications. 2012: 84330N. [22] Halavanau A, Ha G, Qiang G, et al. Microlens array laser transverse shaping technique for photoemission electron source[DB/OL]. arXiv preprint arXiv: 1609.01661, 2016. [23] Jin Yuhua, Hassan A, Jiang Yijian. Freeform microlens array homogenizer for excimer laser beam shaping[J]. Optics Express, 2016, 24(22): 24846-24858. doi: 10.1364/OE.24.024846 [24] Tomizawa H, Dewa H, Taniuchi T, et al. Adaptive 3-D UV-laser pulse shaping system to minimize emittance for photocathode RF gun and new laser incidence system[C]//Proceedings of FEL. 2007: 298-305. [25] Gross M, Qian H J, Boonpornprasert P, et al. Emittance reduction of RF photoinjector generated electron beams by transverse laser beam shaping[J]. Journal of Physics:Conference Series, 2019, 1350: 012046. doi: 10.1088/1742-6596/1350/1/012046 [26] Zhou Feng, Brachmann A, Emma P, et al. Impact of the spatial laser distribution on photocathode gun operation[J]. Physical Review Special Topics-Accelerators and Beams, 2012, 15: 090701. doi: 10.1103/PhysRevSTAB.15.090701 -
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