提出一种新的紧凑型强流电子枪结构。紧凑型自聚束微波电子枪是一个多驻波腔结构,最大特点是腔与腔之间相互没有耦合,每腔可分别独立馈入功率和调节相位。通过选择合适的馈入功率和高频相位搭配,能够得到较优的束流品质。在此基础上采用外注入电子束的结构,能进一步增大流强和降低能散度,同时消除电子反轰对阴极工作的不利影响。利用Superfish和Parmela程序对腔体结构和束流动力学反复进行计算,确定了一组结构和工作参数。模拟结果表明出束微脉冲峰值流强可以到18 A,能散度小于2‰,横向发射度小于6 π mm·mrad。最后给出腔体冷侧结果,与模拟计算结果吻合得较好。

Recently,great attention has been paid to short electron pulses because of the requirement for free electron laser(FEL) projects.To generate a 0.2 nC,5 ps,2 MeV electron bunch with a normalized emittance better than 50 mm·mrad without compensation coil,a self-bunching RF gun with independently tunable cells (ITC) is employed,which consists of two independent cavities to compress short pulses.The first cell compresses the beam from a high-voltage DC gun and the second is an acceleration cell.The two cells can be power fed independently,and beams with excellent characteristics can be obtained by choosing appropriate feeding power and phase for the two cells.This paper describes the design of an external injecting ITC RF gun (DC-ITC-RF gun) and presents simulation results of beam parameters as well as RF measurement.Experimental results show that the designed two-cell structure achieves the target parameter values.