Study on electron beam dynamics in a merger section of energy recovery linac light sources

能量回收直线是未来x射线和伽玛射线光源中很有前途的候选光源。由于电子束参数限制了ERL光源的性能，因此高亮度电子束的产生是实现未来ERL光源的关键问题之一。研究了ERL合并中的电子束动力学。合并是将注入和再循环两束合并到同一轨道上的组件。在合并过程中，由于横向空间电荷力、纵向空间电荷力和相干同步辐射的作用，发射度会增加。我们开发了一种设计ERL合并以最小化发射度增长的策略方法，其中发射度增长通过将空间电荷诱导色散与电子加速器包络相匹配来补偿。还开发了粒子跟踪的模拟代码，用于计算ERL合并中的发射度增长。我们已经将我们的发射度补偿技术应用到紧凑型ERL和伽玛射线源的设计中。紧凑型EEL是未来x射线光源的测试设备。基于我们设计的ERL喷射器的典型性能如下：在平均电流100mA （77pC, 1.3GHz）时，标准化误差为0.3 mm-mrad，在10 mA （7.7pC, L3GHz）时，标准化误差为0.1 mm-mrad。

Energy-recovery linac is a promising candidate fir future X-ray and gamma-ray light sources. Since performance of the ERL light source is restricted by electron beam parameters, generation of high-brightness electron beam is one of the critical issues to realize future ERL light sources. We studied on electron beam dynamics in a merger of ERL. The merger is a component to merger two beams, injection and recirculation, into the same trajectory. In the merger, emittance growth may occur due to transverse space charge force, longitudinal space charge force, and coherent synchrotron radiation. We have developed a strategic method to design an ERL merger to minimize the emittance growth, in which emittance growth is compensated by matching space-charge-induced dispersion to betatron envelope. A simulation code for particle tracking has also been developed for calculation of emittance growth in an ERL merger. We have applied our emittance compensation technique to design of the Compact ERL and gamma-ray sources. The Compact EEL is a test facility for future X-ray light sources. Typical performance of ERL injectors based on our design is as follows: normalized eminence 0.3 mm-mrad for average current 100mA (77pC, 1.3GHz), 0.1 mm-mrad for 10 mA (7.7pC, L3GHz).