北京大学DC-SC光阴极注入器的升级设计

Updated design of the DC-SC photo-injector at Peking University

基于直流电子枪-超导加速腔(DC-SC)光阴极注入器样机的初步实验结果,北京大学提出了新的注入器的改进设计。新注入器核心结构包括皮尔斯枪和3+1/2超导腔。文章给出了它们的详细结构参数,然后采用程序,对注入器的束流动力学进行了模拟。结果发现:新注入器可以提供具有高束流品质、高平均流强的电子束,束团的电荷量100 pC,横向发射度低于2 mm.mrad,脉宽5 ps,rms束斑可达0.5 mm,重复频率81.25 MHz;也可以提供电荷量为300 pC低重复频率的高峰值流强的电子束,其横向发射度小于3 mm.mrad,脉宽约为9 ps,以满足北京大学自由电子激光(PKU-FEL)实验平台的要求。

Based on the results of the DC-SC photocathode injector experiments at Peking University, an improved design of the injector is proposed. The new injector ean provide both high average power electron beams with bunch charge of 100 pC, repetition rate of 81.25 MHz, transversal emittance lower than 2 mm· mrad, bunch length of 4 ps, and high peak current electron beams with buneh eharge of 300 pC, transversal emittance lower than 3 mm · mrad and bunch length of about 9 ps. The detailed design of the injeetor, influence of bunch shape to the beam emittance and analysis of solenoid eompensation teehnology are presented in this paper.