Cathode effects on a relativistic magnetron driven by a microsecond e-beam accelerator

Lopez, Mike R.; Gilgenbach, R. M.; Jordan, David W.; Anderson, Scott; Johnston, Mark D.; Keyser, M.W.; Miyake, Hiroto; Peters, C. W.; Jones, M. C.; Neculaes, V.B.; Lau, Y. Y.; Spencer, Thomas A.; Luginsland, J.W.; Haworth, M.D.; Lemke, R.W.; Price, David L.

doi:10.1109/tps.2002.801543

Cited by 44 publications

(14 citation statements)

References 15 publications

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“…This technique of electron prebunching [11] could also be extremely useful in eliminating mode competition and improving the startup in high-power relativistic magnetrons [15]. Imposing an azimuthally varying axial magnetic field would be much simpler and cheaper to implement than microwave priming for high-power magnetrons [16].…”

Section: Discussionmentioning

confidence: 99%

Low-Noise Microwave Oven Magnetrons With Fast Start-Oscillation by Azimuthally Varying Axial Magnetic Fields

Neculaes

Gilgenbach

Lau

et al. 2004

IEEE Trans. Plasma Sci.

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A technique has been proven to significantly reduce the noise and to hasten the startup in microwave signals from dc operating oven magnetrons. The technique is based on imposition of an azimuthally varying axial magnetic field in magnetrons. For an -cavity magnetron operating in pi-mode, the optimal number of periods of azimuthal variations in the axial magnetic field is 2. This technique demonstrates the fastest startup and lowest start-oscillation current by prebunching the electrons. Measurements show dramatic reduction in noise of 600-800 W oven magnetrons operating dc near 2.45 GHz. The sidebands are eliminated ( 30 dB) and the noise within 50 MHz from the carrier is reduced by 30 dB. Noise reduction is observed at low (up to 60 mA), medium (60-200 mA) and high currents (200-300 mA), for both aged and fresh oven magnetrons. The reduction in power and in electronic efficiency is of order of 10%, in this low-noise, fast startup operation.Index Terms-High power microwaves, magnetron, microwave noise.

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Section: Discussionmentioning

confidence: 99%

Low-Noise Microwave Oven Magnetrons With Fast Start-Oscillation by Azimuthally Varying Axial Magnetic Fields

Neculaes

Gilgenbach

Lau

et al. 2004

IEEE Trans. Plasma Sci.

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“…[8,9] These cathodes can be considered as a passive cathodes because the source of electrons is explosive emission plasma which is generated during the application of the accelerating pulse [10,11,12]. The parameters of this explosive plasma (time delay in the plasma generation, plasma density and temperature, plasma uniformity and expansion velocity) depend on the parameters of the accelerating pulse, namely, on its amplitude and rise time.…”

Section: Introductionmentioning

confidence: 99%

Relativistic magnetron operation with explosive emission and ferroelectric plasma source cathodes

Hadas

Sayapin

Kweller

et al. 2009

2009 IEEE International Conference on Plasma Science - Abstracts

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In this report we present results of comparison of experimental research of the relativistic magnetron operation with commonly used explosive emission plasma cathode and novel ferroelectric plasma source (FPS) cathode. The experiments were carried with relativistic Sband magnetron powered by Linear Induction Accelerator (LIA) (~350kV, 4kA, 200ns). Using time-and spaceresolved electrical, optical and spectroscopic diagnostics plasma parameters (density, temperature and expansion velocity) were studied during the accelerating pulse. In the case of explosive emission plasma it was found that the plasma is not uniform and consists of separate plasma spots whose number increases during the accelerating pulse. It was shown that the microwave generation is accompanied by a significant increase in plasma density and ion temperature, up to ∼5·10 16 cm -3 and ∼8 eV, respectively. The plasma electron temperature was found to be ∼8 eV. It was shown that the plasma expansion velocity in the axial direction reaches ∼10 7 cm/s and ≤2·10 5 cm/s in the radial direction. Investigation of the plasma parameters during the magnetron operation with FPS cathode showed also increase of the plasma density up to ∼7·10 14 cm -3 electron and ion temperature up to ∼7 eV and ∼4 eV respectively. It was shown that the application of the ferroelectric plasma cathode allows one to avoid a time delay in the appearance of the electron emission, to achieve better matching between the magnetron and LIA impedances, and to increase significantly (~30%) the duration of the microwave pulse with a ~10% increase in the microwave power. The latter results in generation of microwave radiation to be 30% more efficient than with the use of explosive emission cathode where the efficiency ≤20 %.

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“…Recent advances in high power microwave source technology include relativistic devices such as the relativistic Klystron oscillator [6] and the relativistic magnetron [7]. Either relativistic initial velocity or high acceleration field (many high power microwave devices operate at a relativistic potential greater than 0.5 MeV) require a corresponding relativistic time-centering algorithm.…”

Section: Introductionmentioning

confidence: 99%

Algorithms for accurate relativistic particle injection

Feng

Kim

Verboncoeur

2008

Journal of Computational Physics

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Cathode effects on a relativistic magnetron driven by a microsecond e-beam accelerator

Cited by 44 publications

References 15 publications

Low-Noise Microwave Oven Magnetrons With Fast Start-Oscillation by Azimuthally Varying Axial Magnetic Fields

Low-Noise Microwave Oven Magnetrons With Fast Start-Oscillation by Azimuthally Varying Axial Magnetic Fields

Relativistic magnetron operation with explosive emission and ferroelectric plasma source cathodes

Algorithms for accurate relativistic particle injection

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