Abstract
The gyrotron backward traveling wave amplifier (gyro-BTWA) is introduced and characterized by a linear theory in this study. The gain mechanism, instead of a convective instability, is due to the interference among three backward waves. As a result, a high gain, tunable amplifier can be realized with a short interaction length for lower beam voltage and current. The theoretical results show that a gain of 25 dB at 39.47 GHz can be achieved with an interaction length of 4 cm for a 10-kV, 0.554-A electron beam. These features could make this device as a promising coherent radiation source in the microwave and millimeter wave regimes. © 1997 American Institute of Physics.