THEORY OF GYRO-BACKWARD WAVE OSCILLATORS WITH TAPERED MAGNETIC-FIELD AND WAVE-GUIDE CROSS-SECTION

A theory is developed which describes gyro-backward wave oscillators ( gyro-BWO's) with arbitrarily relativistic electron beams and tapered e xternal magnetic field and waveguide wall radius. For the case of line ar tapering the optimal parameters are found that correspond to highly efficient operation, The frequency tunability as the function of magn etic field and voltage deviations has been analyzed. It is shown how t o use the results given in terms of normalized parameters for designin g concrete gyro-BWO's. For one concrete design the effect of electron velocity spread on the efficiency has been studied.