以场方程和电子运动方程为基础 ,分析了行波管放大器中辐射场演化过程中出现极限环振荡和混沌态的电流阈值 .结果表明 :在某些参数范围内 ,辐射场会出现这些非线性不稳定态 .相互作用区域越长 ,失谐量对阈值的影响越明显 .当器件工作在非线性区域时 ,输出功率与电流、失谐量和相互作用区长度三个参数的关系变得紊乱无序 ,控制这三个参数在输出功率曲线的峰值点上 ,可在非线性区域获得较高的输出功率 . Based on the field equations and the electronic equations of motion, the current thresholds of the limit cycle oscillation and the chaos state in the traveling wave tube amplifier are analyzed. The results show that these nonlinearities will appear in the radiation field in some parameters Unstable state.The longer the interaction area, the more obvious the influence of the detuning on the threshold is.When the device works in the non-linear region, the relationship between the output power and the current, the detuning and the length of the interaction zone become disordered Out-of-order, control these three parameters in the output power curve peak point, in non-linear region to obtain higher output power.