Phase locking of a second harmonic gyrotron using a quasi-optical circulator

Daniel J. Hoppe; Raul M. Perez; Alaudin M. Bhanji; Hezhong Z. Guo; John Rogers; Jeffrey P. Tate

doi:10.1117/12.218574

8 September 1995 Phase locking of a second harmonic gyrotron using a quasi-optical circulator

Daniel J. Hoppe, Raul M. Perez, Alaudin M. Bhanji, Hezhong Z. Guo, John Rogers, Jeffrey P. Tate

Proceedings Volume 2557, Intense Microwave Pulses III; (1995) https://doi.org/10.1117/12.218574
Event: SPIE's 1995 International Symposium on Optical Science, Engineering, and Instrumentation, 1995, San Diego, CA, United States

Abstract

Phase locking of a high power pulsed gyrotron oscillator through the use of a quasi-optical circulator was investigated. A second harmonic gyrotron which features a novel complex cavity, operating at 34.5 GHz, was used in the experiment. The quasi-optical circulator consisted of a 5.75 inch diameter ferrite disk biased with a one kilogauss permanent magnet. A polarizing grid was used to separate the input and output signals in the circulator. In order to couple the gyrotron oscillator output efficiently to the quasi-optical system, a number of mode converters, TE₀₃-TE₀₂, TE₀₂-TE₀₁, TE₀₁-TM₁₁, and TM₁₁-HE₁₁, were required. The insertion loss of the circulator and mode converter chain was approximately 1 dB, and an isolation exceeding 25 dB was achieved. In addition, a low power WR28 waveguide isolator was inserted in the injection signal path, providing an additional 35 dB of isolation, for a total isolation of 60 dB. The injection signal was provided by a synthesized signal generator and a 100 Watt traveling wave tube amplifier. A sample of the gyrotron output signal was obtained through an additional horn and mixed with a sample of the injection signal, producing a difference signal. The injection signal was swept slowly through a known frequency range while the difference signal was recorded. The recorded signals were analyzed off-line, and the locking bandwidth was determined. Experiments were performed for injection powers from 0-60 Watts, and a gyrotron output power of approximately 80-100 kW. Phase locking was observed for all non-zero injection powers.

Citation Download Citation

Daniel J. Hoppe, Raul M. Perez, Alaudin M. Bhanji, Hezhong Z. Guo, John Rogers, and Jeffrey P. Tate "Phase locking of a second harmonic gyrotron using a quasi-optical circulator", Proc. SPIE 2557, Intense Microwave Pulses III, (8 September 1995); https://doi.org/10.1117/12.218574

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