GENERATION MECHANISM OF INTERMODULATION PRODUCTS IN A TRAVELING-WAVE TUBE

To study methods for improvement of the intermodulation product of a traveling-wave tube which amplifies multiple frequencies, the general mechanism was investigated by a large signal analysis. The origin of the intermodulation product is in the nonlinearity of the traveling-wave tube. Previously, the phase nonlinearity has been considered important from the discussion of polynomial expansion of the amplitude and phase transfer functions. In this paper, the relationship between the intermodulation product and the phase nonlinearity is reevaluated theoretically and experimentally for various conditions. At the same time, the modulation components of the electron beam charge density are studied as a factor related directly to the generation of the intermodulation product. As a result, it was found that the fundamental component of the charge modulation components which is in phase with the circuit wave voltage best represents the tendency of the third-order intermodulation product.