0.85 THz 折叠波导行波管的高频特性与结构参数优化分析

由于折叠波导具有准二维结构、功率容量大、易集成等特点，非常适合在THz 频段推广应用，文中对0.85 THz 折叠波导行波管(FW-TWT)的色散和耦合阻抗特性进行了模拟计算与优化，利用等效电路理论、简化理论与CST 仿真计算的方法。根据折叠波导直波导高度需大于注通道的特点，电子注的直流加速电压必须小于某一值；根据MEMS 加工工艺的允许误差范围，对折叠波导结构各部分的参数进行优化，使该结构的色散较平坦与耦合阻抗较大。计算结果表明:电子注的直流加速电压不超过26 kV；注通道填充比为0.1 时，带宽约400 GHz、相速变化率小于1%时带宽约275 GHz(825~1 100 GHz)。该套方法对THz 折叠波导行波管的设计具有重要意义。

Analysis of high frequency characteristics and structure parameteric optimization for 0.85 THz folded waveguide traveling-wave tube

The folded waveguide structure which has enormous advantages can been applied into THz TWT. In the article, a simple theory and equivalent circuit theory were used to analyze high frequency performance of 0.85 THz FW -TWT, and the CST MWS and HFSS codes validate these equivalent theories. The results of simulation and theoretical calculation were coincident. Because FW is a special slow-wave structure, the highest DC voltage was got. In deviation of fabrication dimensions, optimization structure parameters which make 0.85 THz FW-TWT to have wide band and high impedance were got. The results show the limited DC voltage is 26 kV and r0/a(r0represents beam hole radius and a is the width of FW) is about 0.1. The largest cold band width is about 400 GHz and the band width in flat dispersion region is about 275 GHz (825-1 100 GHz) and the change between the lowest and the highest phase velocity is below 1%. The design approach can been used to guide the design of slow-wave structure of THz FW-TWT.