Abstract
A linear theory using Laplace transforms is presented which is applicable to both gyrotron traveling wave amplifiers (gyro-TWT’s) and gyrotron backward wave oscillators (gyro-BWO’s). The validity of the linear theory is verified by comparing it with an existing nonlinear self-consistent theory based on a different approach. In copjunction with a time-dependent multimode particle simulation code, the linear theory is applied to study the stability of harmonic gyro-TWT’s. It is shown that a harmonic gyro-TWT can be made stable to all forms of spontaneous oscillations by employing a multistage interaction structure and that it can generate power levels far in excess of those possible for a fundamental gyro-TWT. The linear bandwidth of a second-harmonic gyro-TWT amplifier is also calculated. © 1992 IEEE