Pulse test of a W-band Second Harmonic Gyrotron Based on a 1.8 T Continuous Operation Solenoid

The pulse test results of W-band second harmonic gyrotrons based on a 1.8 T continuous operation solenoid are presented. When the solenoid is driven by a DC current of 500 A, magnetic field of 1.8 $T$ in the gyrotron cavity region is generated. The power consumption of the solenoid is 21.5 kW. Two TE 02 W-band second harmonic gyrotron were built based on this solenoid. In the pulse test, both harmonic gyrotron operated at the frequency of 94.2 GHz. One of the gyrotrons had a 24 mm cavity, the output power is 11.4 kW when driven by an electron beam of 44 kV, 1.6 A, corresponding to an efficiency of 16.2%. And for the other gyrotron with a 24 mm cavity, the output power is 22.5 kW driven by a 44.6 kV, 3.2 A electron beam, corresponding to an efficiency of 15.8%. These results indicated that a medium power W-band, CW gyrotron without superconducting magnet could be realized.