作为BEPCII预注入器的光阴极注入器

 为了提高并且采用双束加速技术以进一步提高BEPCII正电子从直线加速器注入到储存环的速率，BEPCII(Beijing Electron Positron Collider Upgrade Project) 正在建造带有两个次谐波聚束腔的新预注入器。提出了使用光阴极注入器作为BEPCII预注入器的新方案，其性能优于次谐波聚束系统：发射度和能散至多为次谐波聚束系统的1/4，100%的传输效率，没有卫星束团的干扰，等。此外，还分别对光阴极注入器在高电荷量和低电荷量两种情况下的束流动力学进行了模拟计算和优化研究，并将其性能与正在建造的次谐波聚束系统和旧聚束系统的性能进行了比较和讨论。由此光阴极注入器产生的电子束还可以在将来用作激光-等离子体或激光-非传导性加速结构的尾场加速研究。

Photoinjector as pre-injector for BEPCII

In order to use the two-bunch acceleration technology to further double the positron injection rate from BEPCII (Beijing Electron Positron Collider Upgrade Project) linae to the storage ring, a pre-injector with two SHBs (Sub-harmonic Buncher) is being constructed to replace the old BEPCII bunching system. In this paper, we propose a new scheme to use a photoinjector as the pre-injector, the performance of which is comparable with or better than the sub-harmonic bunching system: at most 25% emittance and energy spread, 100% transport efficiency, absence of satellite bunch, etc. Beam dynamics of the photoinjector based pre-injec-tor in both low charge and high charge cases are studied and compared with both the pre-injector with SHBs and the old BEPCII pre-injector. The high charge beam produced by the new photoinjector can be used as drive beam for laser-plasma and for laser-dielectric wakefield acceleration studies in the future.