Observations of Phase Locking in a Single-Cavity Gyrotron Oscillator

Read, Michael; Seeley, R.; Manheimer, W. M.

doi:10.1109/tps.1985.4316452

Cited by 22 publications

(5 citation statements)

References 9 publications

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“…We will instead compare our result of phase locking for the gyro-BWO with those for the gyromonotrons reported by two groups at NRL [16,17]. In one method [16,17], a circulator was used to isolate P m and P out . A fractional locking bandwidth of --0.03% was achieved with -20 dB injected power.…”

Section: P-/ / /^/ //////// /Yw / / / /Z?mentioning

confidence: 95%

Experimental study of an injection-locked gyrotron backward-wave oscillator

et al. 1993

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A Ka-band gyrotron backward-wave oscillator (gyro-BWO) experiment has been performed to investigate the phase control, fast tunability, and power capability. Efficient injection locking was accomplished by novel circuit arrangements. Maximum power of 113 kW at -19% efficiency was achieved, showing favorable scaling to still higher powers. Stable voltage tuning bandwidth of 5% at 67 kW peak power was also observed. The measured performance has demonstrated a strong potential of the gyro-BWO for new applications requiring high-power tunable millimeter-wave sources.PACS numbers: 42.52,+x, 85.10.JzResearch on tunable high-power coherent radiation sources in the millimeter through submillimeter spectral range has been a subject of growing interest. Potential applications of such sources include electron cyclotron heating of fusion plasmas, deep space communications, high resolution radars, spectroscopic studies, and drivers of ultra-high-power free-electron-laser amplifiers. A promising candidate, the gyrotron backward-wave oscillator (gyro-BWO), has been theoretically analyzed [1][2][3][4][5][6][7][8] and experimentally demonstrated [9][10][11]. The gyro-BWO is based on the electron cyclotron maser instability on a backward waveguide mode resonantly driven by a forward propagating electron beam (Fig. 1). Counter streaming between the beam and the wave establishes an internal feedback loop, thus allowing the oscillation to take place in a nonresonant structure and its frequency tunable through either the magnetic field or the beam voltage. Also, the cyclotron frequency shift makes resonant interaction possible in a fast-wave circuit which gives the gyro-BWO much greater power handling capability than the conventional BWO.An experimental study of a Ka-band TEfo mode gyro-BWO at the Naval Research Laboratory (NRL) [9,11] achieved a maximum power of 7 kW at nearly 20% efficiency. The 3 dB voltage and magnetic tuning ranges were, respectively, 3% and 13% (with the beam parameters optimized during the tuning). A 140 GHz TE°2FIG. 1. co-k 2 diagram showing the operating conditions of the gyro-BWO. fl e is the rest mass cyclotron frequency of the electron. v z is the average axial velocity. mode gyro-BWO experiment is being conducted at MIT [10] and a 55 GHz TE°i mode gyro-BWO experiment is planned by the UCLA group [7]. All these experiments employ a reflection-type output circuit, that is, the oscillation power is extracted at the collector end after being reflected from the beam entrance end.The NRL experiment [11] has demonstrated broadband magnetic tunability and unexpectedly high efficiency at a relatively low beam voltage (33 kV). These encouraging properties have generated a great deal of current interest in gyro-BWO research. On the other hand, there are issues of physical interest as well as practical importance which remain to be addressed, such as the spectral purity, the phase and frequency controllability, and the stability of fast voltage tuning. In addition, the peaking of output power (at a few kW) at a relat...

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Section: P-/ / /^/ //////// /Yw / / / /Z?mentioning

confidence: 95%

Experimental study of an injection-locked gyrotron backward-wave oscillator

et al. 1993

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“…4). Such a scheme permits to lock the frequency of megawatt power gyrotron unlike to the schemes used in previous experiments for low-power gyrotron with direct input of an external signal [3,4]. Dependence of the locking bandwidth on the power of the magnetron signal was determined (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Locking of gyrotron oscillation frequency by an external monochromatic wave seems to be a promising way for obtaining such source. Although in the recent decades influence of the external monochromatic signal on the gyrotron operation was studied in a number of publications [1][2][3][4][5][6], specific designs of megawatt power level gyrotrons have not been discussed. Study of frequency stabilization by a wave coming into the cavity from the external tract became of particular interest since the development of the quasi-optical converter which allows to transform a large part of wave coming from the output section into the gyrotron operating mode at the Institute of Applied Physics RAS (IAP RAS) [7].…”

Section: Introductionmentioning

confidence: 99%

Influence of mode competition and external wave frequency modulation on gyrotron frequency locking

Novozhilova¹,

Bakunin²,

Chirkov³

et al. 2017

EPJ Web Conf.

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“…15 The reinjected signal and original oscillation tend to form another steady-state phase relation, in which the phase difference between these two signals is constant with time. [16][17][18] The phase relation favors certain frequencies of oscillation, thus resulting in stepwise tuning curves. Such a frequency pulling effect is critical to parameter-sensitive oscillation, such as gyro-BWO.…”

Section: Introductionmentioning

confidence: 99%

Stepwise frequency tuning of a gyrotron backward-wave oscillator

Chang

Chen

2004

Physics of Plasmas

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The gyrotron backward-wave oscillator (gyro-BWO) features broadband tunability, but ragged tuning curves are frequently observed experimentally. Accordingly, a Ka-band gyro-BWO experiment with external circuit mismatch was conducted to examine its tuning properties at two reflected strengths: one is slightly mismatched (15 dB reflection) and the other can be categorized as matched (30 dB reflection). Stepwise frequency tunings by varying the magnetic field, the beam voltage, and the beam current were observed under mismatched conditions. A self-locking model was introduced using the concept of injection-locking, where the output and reinjected signals tend to form a stable phase relation, favoring certain discrete oscillation frequencies. The observed frequencies agree closely with the calculated frequencies. Smooth tuning curves were also obtained, revealing a remedy for the stepwise tuning of a gyro-BWO.

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Observations of Phase Locking in a Single-Cavity Gyrotron Oscillator

Cited by 22 publications

References 9 publications

Experimental study of an injection-locked gyrotron backward-wave oscillator

Experimental study of an injection-locked gyrotron backward-wave oscillator

Influence of mode competition and external wave frequency modulation on gyrotron frequency locking

Stepwise frequency tuning of a gyrotron backward-wave oscillator

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