A 60 GHz gyrotron development program
Abstract
The original objective of this program was to develop a microwave amplifier or oscillator capable of producing 200 kW CW power output at 110 GHz. The use of cyclotron resonance interaction was pursued, and the design phases of this effort are discussed. Later, however, the program's objective was changed to develop a family of oscillators capable of producing 200 kW of peak output power at 60 GHz. Gyrotron behavior studies were performed at 28 GHz to obtain generic design information as quickly as possible. The first experimental device at 60 GHz produced over 200 kW of peak power at a pulse duration of 20 microsec. Heating problems and mode interference were encountered. The second experimental tube incorporated an optimized gun location but also suffered from mode interference. The third experimental tube included modifications that reduced mode interference. It demonstrated 200 kW of peak output at 100 ms pulse duration. The fourth experimental tube, which used an older RF circuit design but in a CW configuration, produced 71.5 kW CW. The fifth experimental tube incorporated a thinner double-disc output window which improved window bandwidth and reduced window loss. This tube also incorporated modifications to the drift tunnel and cavity coupling, which had proven successful in the third experimental pulse tube tests. It produced 123 kW of CW output power at 60 GHz RF load coolant boiling and tube window failure terminated the tests. A new waterload was designed and constructed, and alternative window designs were explored. A secondary task of developing a 56 GHz CW tube produced in excess of 100 kW CW at this alternate frequency. Testing of the sixth experimental tube resulted in operation at CW output power in the range of 200 to 206 kW for an hour. The seventh tube was operated for about forty-five minutes with CW power output over 200 kW.
- Publication:
-
NASA STI/Recon Technical Report N
- Pub Date:
- 1986
- Bibcode:
- 1986STIN...8712791S
- Keywords:
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- Cyclotron Resonance Devices;
- Microwave Amplifiers;
- Oscillators;
- Waveguides;
- Carrier Waves;
- Electromagnetic Interference;
- Experiment Design;
- Extremum Values;
- Modal Response;
- Pulse Duration;
- Electronics and Electrical Engineering