大功率双频段毫米波螺旋线行波管抑制返波振荡的研究

Suppression of Backward-Wave Oscillation in High-Power Dual-Band Millimeter Wave Helix-Traveling Wave Tube

基于高效率双频段毫米波螺旋线慢波结构的设计,探讨了影响返波振荡起振长度的因素。在相速度跳变/渐变结构的输入段引入了相速渐变段,增大了返波振荡的起振电流,设计出了一种新型可抑制返波振荡的螺距分布结构。采用此结构,优化之后使得双频段Ka（33-36 GHz）波段和Q（43.5-46.5GHz）波段的返波增益在返波方向均小于15 d B,从而抑制了返波振荡。

Here,we addressed the suppression of backward-wave oscillation（ BWO） in the high-power dual-band millimeter wave helix-traveling wave tube（ TWT）,based on the design of high-efficiency dual-band millimeter wave helix slow wave structure（ SWS）. The backward wave gain and normalized oscillation start-up length at the input of conventional negative-positive phase velocity tapering SWS were simulated with software MTSS. The impact of the 1st attenuator length,e-beam current and filling factor,on the normalized oscillation start-up length was investigated. The simulated results show that the normalized oscillation start-up length decreased with the increases of e-beam current and filling factor,but increased with an increase of the 1stattenuator length. A novel pitch taper,designed with the optimized pitch-distribution and inserted at the input,significantly suppressed the backward-wave oscillation,because the backward wave gains in Ka（ 33 - 36 GHz） and Q（ 43. 5 - 46. 5 GHz） bands were less than 15 d B.