同轴波导虚阴极振荡器二极管参数优化的研究

采用粒子模拟研究了同轴波导虚阴极振荡器二极管参数对微波效率和频率的影响,得到了由二极管参数改变引起的二极管阻抗变化及其对微波效率的影响规律. 借鉴具有慢波结构的高功率微波器件中微波模式特性阻抗的计算方法,给出同轴波导虚阴极振荡器中微波主模式特性阻抗的理论计算公式. 将理论计算结果与由粒子模拟对器件进行优化后得到的二极管阻抗进行比较,发现当反映电子束特性的二极管阻抗与微波主模式特性阻抗匹配时,虚阴极振荡器具有较高的束波功率转换效率. 进一步用特性阻抗对其他几种典型结构的虚阴极振荡器进行分析,验证了该方法的合理性,为设计高效率虚阴极振荡器提供了理论指导. 关键词： 虚阴极振荡器 同轴波导 二极管参数 特性阻抗

Theoretical and numerical study on optimization of diode parameters in virtual cathode oscillator

The dependences of microwave efficiency and frequency on the parameters of diode in virtual cathode oscillator (VCO) are studied with particle-in-cell simulations, which further gives the effects of diode impedance on microwave efficiency and frequency. The characteristic impedance of microwave mode in virtual cathode oscillator is derived as in other high power microwave generators with slow-wave configurations and is used to analyze the optimization of diode parameters. It is shown that the optimal values of diode parameters are obtained when the diode impedance matches with the characteristic impedance of microwave mode in VCO with coaxial wave guide as well as in VCOs with other configurations. This is a good theoretical explanation for the optimization of diode in VCO and can be used to guide the design of devices.