内导体半径对同轴相对论返波振荡器工作频率的影响

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

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。

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.To sum up,the experimental results are in good agreement with the results of the theoretical analysis.