慢波结构加工精度对太赫兹表面波振荡器的性能影响

Effect of Fabrication Precision of Slow Wave Structure on Performance of Terahertz Surface Wave Oscillator

随着频率的升高,慢波真空电子器件中慢波结构的尺寸迅速缩小。为给太赫兹波段器件的设计和加工提供指导,研究了慢波结构加工精度对0.34 THz过模表面波振荡器的性能影响。采用小信号理论和自行研制的全电磁粒子模拟软件UNIPIC,模拟分析了矩形波纹慢波结构的周期、深度和宽度等参数在设计值附近变化时,热腔色散曲线和输出脉冲的频率、功率、起振时间及脉宽等关键参数的变化。结果表明:器件工作点对慢波结构的尺寸精度比较敏感,使得输出太赫兹脉冲的特征产生较大波动;10%的深度和周期公差将导致器件没有输出,宽度则容许近20%的加工公差。最后采用微细电火花工艺给出了不锈钢慢波结构的加工实例,并讨论了提高慢波结构加工精度的方法。

The influence of the fabrication precision of the rectangularly corrugated, overmoded slow-wave-structure （SWS） ,such as the period, depth and width of the corrugated structure, on the characteristics of the terahertz suri^tce wave oscillator （SWO）, including but not limited to the dispersion, the frequency, power, width and start-up time of the pulsed radiation, was empirically approximated, mathematically modeled, theoretically analyzed in small-signal theory of SWO, and numerically simulated with full electromagnetic particle-in-cell （PIC） code UNIPIC. The simulated results show that the dimension precision of SWS significantly affects the working point of SWO and accouts for the fairly large fluctua- tion of the terahertz pulsed output. To be specific, 10% tolerances of the dpeth and period completely eliminate the out- put;whereas 20% tolerance of the width little affects the output. A prototyped stainless-steel SWS was sucessfully fabri- cated by mireo-electrical discharge machining （miero-EDM）.