外注入式独立调谐微波电子枪的概念设计

为得到微脉冲束团长度在百fs量级且高重复频率，设计了一种紧凑型的强流电子枪结构独立调谐微波热发射电子枪。该电子腔具有双驻波加速腔，两个驻波加速腔之间相互没有耦合，可以分别独立地馈入功率、调节相位。通过优化功率与相位，可以得到较优的束流品质，同时避免了磁铁和激光系统的使用，使得结构更加紧凑。并采用外注入式结构增大流强、降低能散度，同时消除电子反轰对阴极的负面影响。对不同结构参数的腔体进行1维和3维束流动力学计算，可以得到较为理想的腔体参数。通过调节预注入器的馈入功率和粒子入射相位，可以进一步的压缩束团长度。

Conceptual design of independently tunable cells RF gun with external injecting structure

To obtain the micro-pulse bunch with the order of hundred femtoseconds length and high repetition rate, the paper proposes the independently tunable cells (ITC) RF gun, which has a double-cell structure with the cells being power fed independently. By choosing appropriate feeding power and phase of the two cells, this ITC-RF gun can achieve bunches of excellent characteristics. Additionally, the application of α-magnet and laser system can be avoided, which leads to more compact layout. An external injecting ITC-RF gun (DC-ITC-RF gun) structure is designed accordingly. The external injecting structure can increase beam current, decrease energy spread, and cancel the back-bombardment effect almost completely. By means of 1-D and 3-D beam dynamics calculation with different structure parameters, a group of RF parameters are obtained for better beam characteristics. Then the paper designs a pre-injector so that particles can be accelerated to 10 MeV. By choosing appropriate feeding power and incident particle phase for the pre-injector, the bunch length can be further compressed.