Abstract :
The average power capability of beam type microwave amplifiers is limited by the intercepted beam power density in the interaction region. In order to increase the area of the slow-wave structure adjacent to the beam a novel circuit consisting of an inner and outer coaxial structure suitable for interaction with a hollow beam has been developed. The combination of this circuit and a hollow-beam gun of the magnetron injection type has resulted in a traveling-wave amplifier with very unusual characteristics. The Hughes Microwave Tube Division has developed a hollow-beam traveling-wave amplifier using these principles, which provides 100 kw ot peak power, with 10 db gain, over a 10% bandwidth at X-band and possesses a 25 kw average power capability. Moreover, the use of a high perveance hollow beam has resulted in a low voltage design with high C operation. The characteristics of this amplifier are similar to solid-beam amplifiers utilizing coupled-cavity type slow-wave circuits, with the important difference of providing a tremendous increase in the average power capability.
