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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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