Generation of terahertz (THz) radiation from an interaction between sheet electron beam with the electromagnetic wave in a smooth transition ridge-loaded folded waveguide (RFWG) structure is proposed in this article. It was found that in the structure the electric field density can be increased so that the average interaction impedance of the proposed circuit is higher than that of conventional sheet beam (SB) folded waveguide (FWG) circuit. According to the beam–wave simulation results, at a designed voltage of 13.1 kV and an electron beam current of 100 mA, a maximum output power of 91.13 W can be achieved, which corresponds to a power gain of 32.88 dB and an efficiency factor of 6.96%. Therefore, the smooth transition RFWG traveling wave tube (TWT) should be considered as a promising THz radiation source. Moreover, based on a recently published 3-D nonlinear theory for a SB FWG-TWT, a version of the 3-D large-signal frequency-domain nonlinear theory model representation for the proposed smooth-transition SB RFWG-TWT was developed. The code is orders of magnitude faster than, and nearly as accurate as, full 3-D particle-in cell (PIC) simulations.

中文翻译：

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基于脊形折叠波导SWS的太赫兹薄板TWT的数值模拟和理论分析

本文提出了由薄电子束与电磁波在平滑过渡脊形加载折叠波导（RFWG）结构中的相互作用产生太赫兹（THz）辐射的方法。已经发现，在该结构中，可以增加电场密度，从而使得所提出的电路的平均相互作用阻抗高于传统的片状梁（SB）折叠波导（FWG）电路的平均相互作用阻抗。根据束波仿真结果，在13.1 kV的设计电压和100 mA的电子束电流下，可以实现91.13 W的最大输出功率，这相当于32.88 dB的功率增益和效率系数。 6.96％。因此，应将平滑过渡RFWG行波管（TWT）视为有前途的THz辐射源。而且，基于最近发布的SB FWG-TWT的3-D非线性理论，开发了用于所建议的平滑过渡SB RFWG-TWT的3-D大信号频域非线性理论模型表示的版本。该代码比完整的3D粒子内单元（PIC）仿真要快几个数量级，并且几乎与之一样准确。