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

研制了一种用于科研综合实验室(电源为3phi 220V/3线)的宽带微波紧凑型自由电子激光振荡器。研究结果如下：(1)螺线管感应结构螺旋摇摆器的研制。结果表明，平面结构和螺旋结构的摆动器场BW在缩短摆动周期方面具有比较的价值，我们得到了一种适用于自由电子激光实验的螺旋摆动器场，它使用的低能电子束小于强导向场BO所需的I MeV。(2)电子束系统的设计。在考虑了热阴极的供电方式后，最终采用了1.aB6的CO_2激光加热阴极，这是通过我们实验室的一台70W的CO_2激光器来实现的。电子枪采用E-GRON程序设计，通过10-100KV的加速电压和Io=10 mA的电流，将聚焦电子束传输到漂移管上。(3)自由电子激光工作分析。在波长为16 mm，BW=250g，Bo=3 kg的情况下，电子束能量EO=111-200keV的变化给出了振荡频率15.4-37.2 GHz(波长19.5-8.1 mm)的变化。在EO=120keV，Io=5omA(束流功率6kW)，摆动周期数为30的情况下，饱和输出为50W，小信号增益为0.4%。根据上述结果，建立了我们所需要的宽带微波紧凑型自由电子激光振荡器的基础数据和技术。此后，我们想要构建自由电子激光振荡器，并获得自由电子激光运转的实验数据。

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.