基于动态相速渐变（DVT）技术的多注太赫兹折叠槽波导行波管研究

本项目提出一种基于动态相速渐变（DVT）技术的多注太赫兹折叠槽波导行波管，解决太赫兹折叠波导行波管互作用效率低，频带宽度小等问题。首先利用折叠槽波导中欧姆损耗低于传统折叠波导的优点提高互作用效率。其次利用DVT技术通过逐渐改变行波管后端慢波结构尺寸，调整工作频段内高频段的太赫兹波相速度，使其与互作用电子保持再同步状态，将更多能量转换为太赫兹波，从而扩展带宽及增加频带宽度。同时采用带状多电子注技术（相同总电流强度下电子注拥有小电流密度）可以降低所需的磁场，降低行波管制造难度及成本。而且折叠槽波导行波管与传统折叠波导行波管类似可以在低相速，即低电压下工作。本项目将对这种新型器件进行理论分析、数值模拟和实验研究。解决的关键技术及研究成果为发展大功率、宽频带、高效率、低电压太赫兹放大器奠定基础。本项目的目标是设计一个在220-240GHz输出功率大于等于100W的太赫兹放大器。

A multi-beam folded groove waveguide (FGW) terahertz traveling wave tube (TWT) based on dynamic velocity taper (DVT) technology is proposed in this project to solve the problems such as low interaction efficiency and small frequency bandwidth experienced by the folded waveguide traveling wave tube (FW-TWT). Firstly, it takes the advantage of the characteristic electric field existed in the FGW, which exhibits lower Ohmic losses than the conventional FW-TWT, to increase the interaction efficiency. Secondly, by exploiting the DVT technology, namely adjusting the phase velocity of the terahertz wave in the upper end of the operating frequency band through a gradual change of the dimensions in the later part of the slow wave structure, to maintain the synchronous condition between the wave and the electron beam, and to transfer more electron energy to the wave, hence improving the frequency bandwidth. Furthermore，the use of multi sheet shaped beam (hence lowering the beam current density while maintaining a total beam current unchanged) allows the TWT to operate with a smaller magnetic field which could reduce the manufacturing difficulties and the cost of the magnet. In addition, similar to the FW-TWT, the FGW-TWT could also operate at a low beam voltage, i.e. in the low phase velocity region. The project will study the novel device through theoretical analysis, numerical simulations and experimental measurements. The study will lay a foundation for the development of high power, broad bandwidth, high efficiency terahertz amplifiers which could operate with a low voltage. The aim of the project is to design a terahertz amplifier with an output power of over 100 W in the frequency bandwidth of 220-240 GHz.