导引磁场控制相对论速调管放大器电子束收集的方法

RKA electron beam collection controlled by guiding magnetic field

通过改变磁场位形,利用粒子模拟方法,研究了相对论速调管放大器(RKA)中电子束收集位置对器件效率和工作稳定性的影响。合适的电子束收集位置对增加输出腔区束波作用强度、减小输出腔区强流电子束的空间电荷势能以及减少RKA中反射电子数量非常有利。对一个工作频率2.85GHz的RKA的电子束收集方式进行了改进,在电子束参数为510keV和8.1kA,注入微波功率500kW和导引磁场1.5T时,模拟得到了1.4GW的微波输出,效率33.7%,增益33.8dB,改进电子束收集方式之前的模拟结果为输出功率1.1GW,效率为26.3%。利用Surperfish设计了改进收集方式后所需的磁场位形,并导入粒子模拟程序进行了模拟,实现了对电子束收集位置的有效控制,输出效率为32%。

An electron beam collection method in relativistic klystron amplifier（RKA） controlled by magnetic field is proposed.The influence of collection position on beam-wave conversion efficiency and stability of RKA is also analyzed.When the electron beam is collected at a proper position,the interaction between beam and microwave can be enhanced,and the space charge potential of electron beam and the number of reflected electrons can be reduced.An RKA has been improved with electron beam collection at the frequency of 2.85 GHz.When the electron beam voltage and current are 510 keV,8.1 kA,the input power is 500 kW,and the guiding magnetic field is 1.5 T,an output power of 1.4 GW is obtained,and the corresponding efficiency and gain are 33.7% and 33.8 dB,respectively.When the beam collection is not improved,the output power is 1.1 GW,and the efficiency and gain are 26.3% and 33.4 dB,respectively.The magnetic field pattern needed for the improved collection in the RKA is designed by Superfish,and the field data are imported into the PIC code.The related simulation results show that the electron beam collection position is controlled effectively by the magnetic field,and the beam-wave conversion efficiency is 32%.