An investigation of X-band gyrotwystron amplifiers

Experimental and theoretical studies of the cyclotron maser instability in the gyrotwystron configuration have been made. Several configurations of a three-stage TE0.1 mode X-band gyrotwystron with variable buncher cavity lengths, drift lengths, and output sections, have been tested. An efficiency in excess of 27.5% and a full-width half-maximum (FWHM) bandwidth of 1.6% have been demonstrated for a 16-kV, 1-A electron beam. This bandwidth represents a substantial improvement of over the 1% bandwidth measured for a three-cavity gyroklystron cavity employing the same input and buncher cavities, Experimental results from three gyrotwystron configurations have been compared with predictions of theory and good agreement was obtained. The effect of velocity spread on efficiency and bandwidth was also studied, The favorable comparison of experimental and theoretical data indicates that the model is a useful tool in the design and analysis of gyrotwystron amplifiers.