ABSTRACT

In this article, the complete design and beam-wave interaction studies of W-band gyro-TWT amplifier have been presented. The gyro-TWT has been designed to operate at second harmonic TE₀₂ mode to reduce the magnetic field requirement. A triode-type magnetron injection gun has been designed and optimized for low-velocity spread using E-GUN. A novel, mode selective input coupler with a gradually tapered slotted waveguide has been used to feed the desired TE₀₂ mode and suppress the reflection and spurious oscillations at the input end (upstream). To abridge the absolute instability of the operating mode and backward wave oscillations caused by spurious modes, a periodic lossy dielectric-loaded RF structure has been adopted. The particle-in-cell simulation of the amplifier predicted a peak RF output power of ∼500 kW with ∼3.6 GHz bandwidth, ∼20% efficiency, and ∼32.2 dB saturated gain for the DC input of 100 kV, ∼25 A with 4% axial velocity spread and velocity ratio of 1.22. Further, to extract the output power with minimum reflection, a double-disc window has been studied. An undepressed curved collector is also designed using E-GUN and its simulation predicted a maximum heat wall loading of ∼0.39 kW /cm².

摘要

在本文中，介绍了 W 波段陀螺仪-TWT 放大器的完整设计和波束相互作用研究。陀螺仪-TWT 设计为在二次谐波TE ₀₂模式下运行以降低磁场要求。三极管型磁控管注入枪已针对使用 E-GUN 的低速传播进行了设计和优化。一种新颖的模式选择输入耦合器，带有逐渐变细的开槽波导，已用于馈送所需的TE ₀₂模式并抑制输入端（上游）的反射和寄生振荡。为了消除工作模式的绝对不稳定性和杂散模式引起的后向波振荡，采用了周期性有损介质加载射频结构。放大器的粒子单元模拟预测峰值 RF 输出功率为 ~500 kW，带宽为 ~3.6 GHz，效率为 ~20%，对于 100 kV、~25 A 和 4 的直流输入，饱和增益为~32.2 dB ％轴向速度分布和速度比为 1.22。此外，为了提取具有最小反射的输出功率，已经研究了双盘窗口。还使用 E-GUN 设计了一个未压缩的弯曲收集器，其模拟预测的最大热壁负荷为 ∼0.39 kW /cm ²。