渐变螺距螺旋线慢波系统高频特性的仿真分析

 为实现渐变螺距螺旋线慢波结构高频参数的高精度估计，基于MAFIA仿真平台，研究了螺距变化对超宽带螺旋线慢波系统(4~18 GHz)的色散、互作用阻抗与衰减常数的影响，获得了各高频参数随螺距变化的规律。研究表明：相速几乎随螺距增大而线性变大，互作用阻抗与螺距是非线性的关系，衰减常数随螺距增大而非线性地减小；由于在维持电子注与电磁波速度同步的限制下，螺距变化的幅度不可能很大，因此可近似按线性关系来处理互作用阻抗及衰减常数与螺距之间的关系。由此提出了一种可精确计算渐变螺距螺旋线慢波结构高频参数的方法－线性插值法

Simulation analysis of cold-test characteristics of pitch-tapered helical slow-wave structures

Based on the MAFIA simulation platform,the effects of helix pitch on dispersion,interaction impedance and attenuation characteristics are analyzed for an ultra-wide band(4~18 GHz) helical slow-wave structure.The rules of the cold-test characteristics changing with helix pitch are also studied and it turns out that,with increasing helix pitch,the phase velocity increases linearly,the interaction impedance changes nonlinearly and the attenuation constant decreases nonlinearly.At the same time,with the limitation of the synchronism between the electron beam and the electromagnetic wave,the change of pitch is small and therefore an approximate linear relation can be introduced.Based on these effects and rules,the linear interposition method is suggested to get the cold-test characteristics for structures with linearly-tapered pitch.