中文摘要：

采用过模结构,克服常规返波管（BWO）中截止径的限制,提高器件内径,有效地降低同等功率条件下器件内表面的强场,使其低于器件内表面的强场击穿阈值,可以克服器件内表面的强场击穿问题。根据BWO的振荡机理,引入过模反射腔,并使其同相应的慢波结构匹配,克服了过模结构中的模式竞争问题,提高了电子束同慢波结构互作用效率。从理论和模拟两个方面研究了过模返波管中的模式控制,设计了一个X波段输出功率接近10 GW、效率约50%的过模返波管器件。

英文摘要：

Internal field emission breakdown in the electro-dynamic structures of high-power microwave devices can seriously limit the devices＇ output power and pulse duration.Increasing the diameter of the electro-dynamic structure beyond the cut-off radius can reduce these internal fields to below critical breakdown levels,but may introduce mode competition as unwanted side effects.An over-sized backward wave oscillator with rectangular profile corrugations is designed to produce TM01 high power microwave radiation without mode-competition.The slow wave structure and the reflector are matched to achieve mode selection and enhance interaction efficiency.The physical mechanism for mode selection is explored both in theoretical investigation and particle in cell simulation.