Experimental study of an injection locked gyro-BWO

Summary form only given. High power handling capability and broad-band frequency tunability of the gyrotron backward wave oscillator (gyro-BWO) have been demonstrated in a number of experiments. In Kou et al.´s work (1993), the injection locking technique was employed to achieve phase control and spectral purity. Here, we present further studies of a Ka-band injection-locked gyro-BWO, operating in the TE/sub 11/ mode at the fundamental cyclotron frequency. The interaction length is 3 cm. The beam voltage and current are, respectively, 100 kV and 4 A with an estimated velocity ratio of 1. Contrary to our expectation, it is found that the output power increases with the locking power. This effect becomes more apparent as the free running frequency approaches the cutoff frequency (33.1 GHz).