Research on compact FEL as a broad-band millimeter wave-microwave oscillator

研究了一种用于科研一般实验室的宽带微波紧凑型FEL振荡器（供电3phi 220V/3线）。所得结果如下：(1)电磁感应结构螺旋摆动器的研制。结果表明，平面结构和螺旋结构的摆动场Bw在减小摆动周期方面具有比较价值，并利用弱引导场Bo所需的小于1 MeV的低能电子束获得了一种有用的螺旋摆动场。(2)电子束系统设计。在考虑了热阴极在真空室的供电情况后，我们最终采用了1。利用CO_2激光对aB6阴极加热，是利用本实验室一台70w CO_2激光设备实现的。电子枪采用E-gun代码设计，在加速电压10-100kV、电流Io=10mA的条件下，能将聚焦电子束传输到漂移管中。(3) FEL运行分析。当lambdaw= 6mm, Bw=250G, Bo=3kG时，电子束能量Eo=111-200keV的变化频率为15.4-37.2GHz（波长19.5-8.1mm）。在Eo=l20keV, Io=5OmA（波束功率6kW），振荡周期数为30时，饱和输出为50W，小信号增益为0.4%。根据上述结果，建立了宽带微波紧凑型FEL振荡器所需的基础数据和技术。接下来，我们将构建自由电子激光器，并获得自由电子激光器工作中的实验数据。

A broad band microwave compact FEL oscillator was studied for the purpose of operating in general laboratory for scientific research(electric supply 3phi 220V/3 lines). The results obtained are as follows.(1)Development of a helical wiggler in solenoid induced structure. It becomes clear that the wiggler fields Bw with planar and helical stmcture have comparative values as decreasing the wiggler periods lambdaw, and we obtained an useful helical wiggler for FEL experiment using low energy electron beam less than I MeV needed for strong guiding field Bo.(2)Design of electron beam system. After considering the power supply of thermal cathode set out or in the vacuum chamber, finally, we adopted a 1.aB6 cathode heating by CO_2 laser, It was realized owing to taking a 70 W CO_2 laser equipment in our laboratory. The electron gun is designed by E-gun code, and it can be propagated an focusing electron beam to a drift tube through the accelerating voltage 10-100kV and current of Io=10mA.(3) Analysis of FEL operation. In case of lambdaw=I6mm, Bw=250G, Bo=3kG, the variety of electron beam energy Eo=111-200keV gives variety of oscillation frequency 15.4-37.2GHz(wavelength 19.5-8.1mm). Further, in case of Eo=l20keV and Io=5OmA(beam power 6kW) and wiggler period number is 30, the saturation output is 50W, and small signal gain is 0.4%.From the results mentioned above, the fundamental data and technology needed for our purpose of the broad band microwave compact FEL oscillator was established. Hereafter, we want to construct the FEL oscillator and to obtain the experimental data in FEL operation.