Lengthy Testing of a $\textit{K}$ -Band Multifrequency Gyro-TWT With Double-Disk External Reflector

We present the results of experimental investigations of multifrequency oscillations in a K-band gyrotron traveling-wave tube (gyro-TWT) with double-disk external reflector. The system operation in multifrequency regime was tested for a prolonged period of time with temperature monitoring by an infrared camera. Based on the measurement results, the possibility of stable generation for a period of several tens of minutes at the output power level of more than 2 kW is demonstrated.