8 September 1995 Phase locking of a second harmonic gyrotron using a quasi-optical circulator
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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.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Daniel J. Hoppe, Daniel J. Hoppe, Raul M. Perez, Raul M. Perez, Alaudin M. Bhanji, Alaudin M. Bhanji, Hezhong Z. Guo, Hezhong Z. Guo, John Rogers, John Rogers, Jeffrey P. Tate, 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); doi: 10.1117/12.218574; https://doi.org/10.1117/12.218574


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