A 57GHz overmoded coaxial relativistic backward wave oscillator with high conversion efficiency and pure TM01 mode output

Chen, Siyao; Zhang, Jun; Bai, Zhen

doi:10.1063/1.5003341

Cited by 9 publications

(2 citation statements)

References 15 publications

(12 reference statements)

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“…Cherenkov oscillators [1][2][3][4][5] driven by relativistic electron beam are widely recognized as one of most promising high power microwave (HPM) sources for the high efficiency and high output power. Especially for the large overmoded coaxial devices [6][7][8][9][10][11], due to the high power handling capacity (PHC) and wide electron beam channel, they are widely used in the high frequency and high power fields. However, there inevitably exist multi-modes in the output microwave, which may have an impact on microwave radiation.…”

Section: Introductionmentioning

confidence: 99%

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An improved corrugated waveguide mode purifier for TEM output in a V-band overmoded coaxial millimeter-wave oscillator

Chen

Zhang

2020

Phys. Scr.

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In the overmoded microwave sources, there inevitably exist multi-modes in the output microwave, so it needs to be purified to obtain the single mode output. However, due to the large longitudinal size, the traditional concave-type purifier is not suitable for coaxial devices with large overmoded ratio. The present paper proposes an improved convex-type purifier based on the coupled wave equations. With this purifier, 99.98% TEM mode can be gained effectively under the conditions of diode voltage 355 kV and beam current 3.0 kA. Compared with the traditional concave-type converter, the improved purifier has the higher coupling coefficient and its longitudinal size can be reduced by 40%.

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Section: Introductionmentioning

confidence: 99%

“…Mode purification can be realized by a variety of structures, such as resonant cavity converter [8], tapered converter [12], nested coaxial converter [13] and corrugated converter [14,15]. The resonant cavity converters always bring forth power reflection that may influence beam-wave interaction.…”

Section: Introductionmentioning

confidence: 99%

An improved corrugated waveguide mode purifier for TEM output in a V-band overmoded coaxial millimeter-wave oscillator

Chen

Zhang

2020

Phys. Scr.

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Excitation and suppression of asymmetrical modes in high frequency coaxial slow wave structures

Chen

Zhang

2019

Journal of Applied Physics

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The interaction characteristics of quasi-TEM mode and EHv1 mode with an electron beam in coaxial slow wave structures (SWSs) are analyzed and compared in this paper. Through theoretical analysis and simulation verification, we find that the asymmetric EHv1 quasi-π mode has high external Q-factor, low starting current, and high temporal growth. It is almost impossible to suppress the EHv1 mode when using single section SWSs. In order to solve this problem, a feasible method is proposed in this paper to suppress the EHv1 mode effectively, under the premise that all modes cannot be exited in single section SWSs, introducing the feedback to ensure that the quasi-TEM mode operates effectively.

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Oversized coaxial relativistic extended interaction oscillator with gigawatt-level output at Ka-band

Duan

Huang

et al. 2019

Physics of Plasmas

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In this paper, an oversized coaxial relativistic extended interaction oscillator (OCREIO) with gigawatt-level output at the Ka-band is proposed. We adopt a four-gap buncher cavity and a three-gap output cavity to increase the power capability and improve the electronic efficiency of the OCREIO. The beam-loading conductance for each mode existing in the buncher cavity is derived based on a small-signal theory. The beam-wave interaction and power capability for the 2π/3 and π modes exciting in the buncher cavity are analyzed. The operation mode 2π/3 is chosen by considering the beam-loading conductance and power capability. In addition, an improved method is proposed to mitigate the electric field intensity of the buncher cavity so as to moderate velocity modulation. The weak velocity modulation offers enough distance to make density modulation, thereby obtaining a relatively high fundamental harmonic current amplitude. Our study on the device performance of the proposed OCREIO, using the particle-in-cell simulation code CHIPIC, predicts an output power of 922.7 MW and a high electronic efficiency of 32.9% at 30.5 GHz, as well as the relatively less time of frequency-lock of self-oscillation <20 ns. The simulated results of the proposed OCREIO motivate us to practically develop the device in the near future.

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A 57GHz overmoded coaxial relativistic backward wave oscillator with high conversion efficiency and pure TM01 mode output

Cited by 9 publications

References 15 publications

An improved corrugated waveguide mode purifier for TEM output in a V-band overmoded coaxial millimeter-wave oscillator

An improved corrugated waveguide mode purifier for TEM output in a V-band overmoded coaxial millimeter-wave oscillator

Excitation and suppression of asymmetrical modes in high frequency coaxial slow wave structures

Oversized coaxial relativistic extended interaction oscillator with gigawatt-level output at Ka-band

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