Effects of beam velocity spread on two-stage tapered gyro-TWT amplifier

Electron beam velocity spread influences the instantaneous bandwidth of a two-stage tapered gyrotron travelling wave tube amplifier. During the velocity spreads, the electron phase-mixing induces frequency-dependent sharp gain dip in the amplifier. The changes in the magnetic field profile, circuit length, velocity spread, and the beam axial velocity cause shifting or lowering of the gain dips. An analytical expression reveals the correlation between these parameters and bandwidth.