A low-frequency crossed-field amplifier for experimental investigations of electron-radio frequency wave interactions

Browning, Jim; Chan, Chung; Ye, J.Z.; Ruden, T.E.

doi:10.1109/27.90324

Cited by 27 publications

(21 citation statements)

References 14 publications

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“…Keeping the injected current small the gain in that case is very low, the output rf power is close to the input, and the space charge effects negligible, yet full bunching and spoke formation are observed in situ due to the large interaction length of that device. Given the unimportance of space charge effects, and the negligible change in V 1 over the applied voltage range, i.e., V 1 ӍV 1 ͑inp͒ regardless of V o , the observed gain was symmetric 12,13 relative to either Ϫ o or V o ϪV BH , in agreement with the previous discussion and a detailed theoretical interpretation. 18…”

Section: ͑39͒supporting

confidence: 88%

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Destabilization of diocotron modes inside structured anode cavities

Riyopoulos

1999

Physics of Plasmas

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Previous stability analysis of low space charge ωe2/Ω2≪1, E×B drifting flows inside smooth anode cavities has shown that they are practically stable against slow wave ω/ck≪1 diocotron instabilities when the flow touches the cathode (cathode layer). It is shown here that the presence of periodically structured anode destabilizes cathode layer modes when their phase velocity matches that of an empty cavity eigenmode, as structured cavities support slow waves in vacuum. An analytic dispersion relation that self-consistently includes the structured anode effects is obtained in the guiding center approximation. The growth rate, related to the onset of magnetron oscillations, scales as γ/ω∼ωD/ω≃1/kd; it is independent of, and remains finite as, ωe2/Ω2→0. The most unstable frequency corresponds to a resonant layer below the flow surface (slightly below the Buneman–Hartree frequency) and the growth rate is found symmetric relative to the detuning from resonance.

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Section: ͑39͒supporting

confidence: 88%

“…The same symmetry in the growth rate vs detuning characterizes the low space charge operation of the related crossed-field amplifiers. 12,13 It is also shown that a negative density slope is required for instability, contradicting an opposite stability condition 4,5 applying to diocotron modes.…”

Section: Introductionmentioning

confidence: 94%

Destabilization of diocotron modes inside structured anode cavities

Riyopoulos

1999

Physics of Plasmas

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“…The original circuit was 40 cm long and 25 cm and had a 1 cm pitch. With a retardation of R=33, the device was relatively short (6 slow wave wavelengths) and had relatively low gain (7 dB) [10], [11].…”

Section: Introductionmentioning

confidence: 99%

“…Four different main cathode types were tested in this work: 1) injected beam, 2) static distributed beam, 3) modulated distributed beam, and 4) modulated injected beam. The injected beam configuration was simulated [9] and validated against the experimental NU data in [10], [11]. The static distributed beam configurations were also studied in that work.…”

Section: Introductionmentioning

confidence: 99%

Simulation of a Time-Varying Distributed Cathode in a Linear Format Crossed-Field Amplifier

Pearlman

Browning

2019

IEEE Trans. Plasma Sci.

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The effects of a temporally modulated, distributed cathode in a linear format crossed-field amplifier (CFA) are simulated in VSim and analyzed. A linear format, 150 MHz, low power (100 W), moderate gain (7 dB), meander line CFA is used as the basis for the simulation model. This paper describes simulations with different time-varying distributed cathodes in which electron injection is modulated at the RF frequency both in and out of phase with the RF input. At low RF input power the modulated electron injection dominates the operation. Injecting in phase with the RF input shows gain increases from 23 dB at 150 mA to 32 dB at 1 A for low cathode modulation power (<0.1 W). The CFA efficiency increased from 2-4% to 20-24% using the electron modulation. The simulation shows distinct cylindrically shaped electron bunches as opposed to spokes because of the synchronous injection. These results suggest that for high power magnetrons electron modulation could improve gain. Index Terms-Crossed-field amplifier (CFA), distributed beam, microwave vacuum electron devices II. SIMULATION MODEL The CFA simulated here is based on a design from Northeastern University [10], [11]. A more detailed description of the original device is given in the original work and in our previous paper [9], but a short summary is given here. The device is a linear format, injected beam, 150 MHz

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“…Examples of these are Magnetrons [1][2][3][4][11][12][13] and Crossed-Field amplifiers (CFAs) [1][2][3][4][13][14][15][16][17][18][19]. Fast-wave devices use the cyclotron frequency for operation; a gyrotron [1][2][3][4]20] is one example of many gyro devices.…”

Section: 13mentioning

confidence: 99%

Simulation of a Crossed-Field Amplifier Using a Modulated Distributed Cathode

Pearlman¹

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I would like to thank the Boise State University department of Electrical and Computer Engineering for financial support of this research. I thank the U.S. Air Force Office of Scientific Research for their financial support under Grant FA9550-12-C-0066. I also express my gratitude to TechX Corporation for their support of our work with Vsim and in particular David Smithe for his help. And, of course, I am immensely grateful to the review committee, Wan Kuang, Kris Campbell, Jim Browning, and Yue Ying Lau for their time and effort in validating this dissertation. I also want to thank Janos Cserna for helping develop much of the experiment, specifically the X-Y stage used to measure the dispersion. I also wish to thank Kyle Straub and Tyler Rowe for their part in developing the experimental setup, and for their collaboration.

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A low-frequency crossed-field amplifier for experimental investigations of electron-radio frequency wave interactions

Cited by 27 publications

References 14 publications

Destabilization of diocotron modes inside structured anode cavities

Destabilization of diocotron modes inside structured anode cavities

Simulation of a Time-Varying Distributed Cathode in a Linear Format Crossed-Field Amplifier

Simulation of a Crossed-Field Amplifier Using a Modulated Distributed Cathode

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