Mechanisms of amplification of short electromagnetic pulses in gyroresonance traveling-wave tubes

Abstract

Traditional gyroresonance traveling-wave tubes (gyro-TWTs) with a smooth waveguide serving as the operating space and gyro-TWTs based on a waveguide with multiturn helical corrugation are considered. A nonstationary nonlinear theory providing for the description of amplification of short pulses in various circuits of such TWTs is proposed. The specific features of amplification of short pulses in helical gyro-TWTs are investigated for the regimes in which the dispersion curves of a normal wave and of an electron flow contact and intersect. In the first case, it is demonstrated that pulses having a spectrum width on the order of the amplification bandwidth can be amplified without distortion of their shapes. In the second case, it is shown that the slip of an extremely short input pulse relative to the electron beam ensures the infeed of one of the fronts of an electromagnetic pulse with an initially unmodulated electron flow. As a result, the pulse amplitude at the output of the interaction space can exceed the saturation amplitude in the regime of stationary amplification of monochromatic radiation.