新型金属丝靶电子源实验研究

电子束在基础科学研究、工农业生产和医疗领域发挥了重要作用。提出了一种新型的电子源技术方案:高功率激光脉冲轰击金属丝靶，可以产生大量能量在百keV量级的热电子，一部分热电子在丝靶表面自生电磁场的作用下沿着丝靶运动，丝靶后方可以获得指向性良好的电子束。实验上成功在金、钨和铜丝靶后方获得了电子束团，测量了束团束斑、电荷量和能谱。铜丝靶单发实验收集到的电子束团总电荷量可达3 nC，能量分布在0～240 keV区间内，能谱在100 keV附近呈现峰值。提出了微波压缩方案，设计了2腔微波聚束腔，利用ASTRA对微波腔压缩过程进行了模拟计算。结果显示，可以将电荷量1 nC、长度55 ps的束团压缩至27 ps，满足后续微波加速器对电子源的要求。

Novel electron source based on interaction between high power laser and metal wire

Electron source generates electron bunch and dominates the electron beam quality for an accelerator. We put forward a novel mechanism of electron source in this paper. A great amount of hot electrons with several hundred keV can be generated during the interaction process between high power laser and metal wire, and some of them fly forward along the wire, guided by EM field. We generate electron beam and measure beam parameters downstream the Au wire, W wire and Cu wire experimentally. 3 nC electrons can be collected by a Faraday-cup for a single shot. Electron energy spectrum is between 0?240 keV continually, and there is a density peak at 100 keV. RF buncher cavity can be used to compress the bunch length short enough for further RF acceleration in main accelerator. Start-to-end simulation has been done with ASTRA code. Electron beam with 55 ps length and 1 nC charge is injected into a 2-cell RF buncher cavity, it can be compressed into 27 ps long, which satisfies the general requirement of the main accelerator on the electron source.