行波管放大器中辐射场的极限环振荡和混沌

以行波管放大器中辐射场的非线性不稳定阈值分析为基础，对辐射场从频率分叉到混沌的演化过程和不同区域这些非线性不稳定态的时间特性和频率特性进行了研究.在“软”非线性区域，辐射场表现为极限环振荡和频率分岔，频谱是离散的且相对于载波频率是不对称的.这种不稳定是阵发性的，适当的调节控制参量，可使器件工作在所需的定态或极限环振荡态上；在“硬”非线性区域，辐射场表现为非周期的随机振荡和频率混沌，频谱连续且频带很宽，场幅值较大的成分集中在接近于零频的低频范围里.这种不稳定是连续性的，不能通过调节参量来消除. 关键词： 行波管 辐射场 分岔 极限环 混沌

Limit cycle oscillating and chaos of the radiation field in a traveling wave tube amplifier

In this paper the evolution of the radiation field from frequency bifurcation to chaos and the temporal and frequency characteristics of the nonlinear unsteady states are investigated, based on the threshold analysis of nonlinear instability for the radiation field in a traveling wave tube amplifier. In the soft nonlinear regime,the nonlinear radiation field is characterized by limit cycle oscillations with frequency bifurcated, and the output power spectrum is discrete and asymmetric around the carrier frequency. This instability is intermittent so that the device can operate in expected steady states or limit cycle oscillation states by slightly adjusting the parameter. In the hard nonlinear regime in which the radiation field is characterized by randomly non-periodic oscillations with frequency chaos, the output power spectrum is continuous and wide, the components with a larger amplitude are restricted in the low-frequency range near zero. This instability is continuous so that it cannot be avoided by slightly adjusting the parameter.