Abstract
A linear theory and a self-consistent theory are used to study the launching loss and the Weibel instability of the gyrotron traveling wave tube (gyro-TWT). Numerical results and a simplified analytical model both show that the launching loss is inversely proportional to the growth rate of the wave, and proportional to the difference between the propagation constant of the forward constant amplitude wave and that of the forward growing wave. In addition, the prediction of the Weibel instability in a fast wave interaction structure by the dispersion relation is verified to be valid even though the assumption of close resonance condition of the linear theory breaks down in this region. Nevertheless, this instability is overwhelmed by the launching loss. © 1995 American Institute of Physics.