内导体半径对同轴相对论返波振荡器工作频率的影响

利用电磁软件Superfish求解了同轴慢波结构中准TEM模对应的π模的电场矢量分布，分析了内导体半径对谐振频率的影响。采用Karat 2.5维全电磁粒子模拟程序设计了一个L波段相对论返波振荡器，研究了内导体半径参数改变对器件工作频率的影响。通过使用半径为0.50，0.75，1.00 cm的内导体，实验测得微波中心频率分别为1.64，1.63，1.61 GHz，变化趋势与理论分析结果一致。实验测得频率比粒子模拟结果仅高0.01 GHz，两者吻合较好。

Influence of inner-conductor radius on operation frequency of coaxial relativistic backward wave oscillator

The dispersion curves of the coaxial slow-wave structure (SWS) with the trapezoidal corrugation are obtained by numerical calculation. The electric field vector of π mode of the quasi-TEM mode and the influence of the inner-conductor radius on resonance frequency are calculated using the electromagnetic software Superfish. In addition, a compact L-band relativistic backward wave oscillator (RBWO) is investigated and optimized in detail with particle-in-cell (PIC) methods (Karat code) to explain effects of the inner-conductor radius. In experiment, the operation frequencies are 1.64 GHz, 1.63 GHz and 1.61 GHz when the inner-conductor radii are 0.50 cm, 0.75 cm and 1.00 cm respectiuely, which shows that the operation frequency decreases with the enlargement of the inner-conductor radius. T