Kα波段介质加载回旋行波管小信号分析与设计

Small-signal theoretical analysis and design of Kα band dielectric loaded gyro-TWT

应用分析回旋行波管绝对不稳定性的Briggs-Bers相碰判据与小信号色散方程,并结合介质加载波导的冷场分析,通过数值计算比较了不同介质加载条件下回旋行波管工作模式的起振电流与寄生模式的起振长度,通过改变加载介质的特性参数从而增加行波损耗可以显著提高工作模式起振电流,并抑制掉寄生模式的返波振荡.结合介质加载波导冷场分析与回旋行波管小信号色散方程,分析了介质加载条件下回旋行波管小信号增益,给出了不同介质加载条件下的回旋行波管的小信号增益带宽曲线.在对介质回旋行波管自激振荡与小信号增益的综合分析基础上,对Kα波段的介质加载回旋行波管进行了具体的优化设计,给出了其工作参数的选取的依据与范围,为非线形分析提供了理论支撑与初始参数.

Using the small-signal theory of the gyro-TWT, a pinch-point analysis based on the theory of Briggs and Bers in combination with the cold field analysis of the dielectric-loaded waveguide is employed to analysis the threshold current of the operation modes and critical oscillation lengths of the spurious mode under different load condition. The analysis concludes that the improvement in the dielectric loss, through altering the load condition can enhance the threshold current and critical oscillation length. The cold field analysis of the dielectric-loaded waveguide and a smooth waveguide dispersion relation is used to analyse the small signal gain of the dielectric-loaded gyro-TWT. The analysis gives the gain-frequency response of a dielectric-loaded gyro-TWT with the normalized background magnetic flux density Bo/Bg, the thickness of the dielectric and beam current as parameters. Through the analysis of the self-oscillation and the small signal gain, the optimum operating parameters of a Ka-band dielectric- loaded gyro-TWT can be got to support the nonlinear analysis.