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

Summary form only given. Stable operation at a saturated gain of 25 dB over a 20% instantaneous bandwidth has been observed with a two-stage K/sub a/-band gyro-TWT amplifier at the Naval Research Laboratory. This experiment demonstrated its viability as a source of broadband high-power millimeter waves. However, it has been observed experimentally that sharp gain reductions occur at certain frequencies. To explain this observation, an analytical theory has been developed which describes the effect of electron beam quality on the device´s instantaneous bandwidth. In the theory, the impact of the beam velocity spread is distilled into a simple expression.