摘要:
论文对0.34 THz大功率过模表面波振荡器进行了模拟设计和初步实验研究.针对高过模比(D/λ≈6.8)慢波结构,根据小信号理论选择了合适的慢波结构尺寸和电子束距壁距离,实现了器件在表面波TM01模的π点附近谐振.根据PIC模拟结果,表面波振荡器可以实现频率和功率分别为0.34 THz和22.8 MW的太赫兹波输出.采用微细电火花加工技术完成了不锈钢慢波结构的一体化精细加工,并基于小型化脉冲功率驱动源搭建了实验装置.初步的实验结果表明,在电子束电压和电流分别约为420 kV和3.1 kA时,0.34 THz大功率过模表面波振荡器输出脉冲的频率范围为0.319—0.349 THz,辐射功率不小于250 kW,脉宽约为2 ns.最后分析讨论了实验输出功率与模拟结果相差较大的原因,为表面波振荡器的性能改善奠定了基础.
Abstract:
The simulation design and preliminary experiment on a 0.34 THz large-power overmoded surface wave oscillator are presented in this paper. For the slow wave structure (SWS) with large overmoded ratio (D/λ≈6.8), a small signal theory is derived for appropriate dimensions of SWS and gap between electron beam and SWS, and makes the device oscillate near the π point of surface wave at TM01 mode. PIC (particle in cell) simulation results show that this SWO (small wave oscillation) can genetate the terahertz wave with frequency and output power of 0.34 THz and 22.8 MW, respectively. SWS with stainless steel is integrally and precisely fabricated by employing mirco-EDM technology, and the experimental setup is built based on a miniaturized pulse power driving source. Results of preliminary experiment and diagnostics show that a terahertz pulse is radiated at a frequency range of 0.319—0.349 THz, a power of no less than 250 kW, and a pulse duration of about 2 ns at beam voltage of about 420 kV and beam current of about 3.1 kA. Finally, the reason for discrepancy between the measured power and the simulation result is analyzed and discussed, laying the foundation for the performance improvement of terahertz surface wave oscillator.
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