Relativistic backward wave oscillator using a selective mode converter

Abubakirov, É. B.; Денисенко, А. Н.; Kovalev, N. F.; Kopelovich, E. A.; Savel'ev, A. V.; Soluyanov, E.I.; Fuks, Mikhail; Yastrebov, V. V.

doi:10.1134/1.1259523

Cited by 17 publications

(11 citation statements)

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“…For the realization of traveling wave tube (TWT) amplifiers [6,7], one can use either the interaction with the 1st (s = 1, point D1) or with the fundamental (s = 0, point A) [3,16,17] decelerated harmonic of the wave co-moving (hν || > 0) with the beam. Among the oscillator schemes, first of all, the backward wave oscillator (BWOs) [1,2,[4][5][6][7][8][9][10][11][12][13][14][15] should be fundamental ( s = 0, point A) [3,16,17] decelerated harmonic of the wave co-moving ( || 0 hν > ) with the beam. Among the oscillator schemes, first of all, the backward wave oscillator (BWOs) [1,2,[4][5][6][7][8][9][10][11][12][13][14][15] should be identified, where the electrons interact with the spatial harmonic of the wave propagating in a backward ( || 0 hν < , points C) direction.…”

Section: Introductionmentioning

confidence: 99%

Quasi-Optical Theory of Relativistic Cherenkov Oscillators and Amplifiers with Oversized Electrodynamic Structures

et al. 2022

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Using the quasi-optical approach, we investigate wave propagation along the periodically corrugated surfaces and their interaction with rectilinear relativistic electron beams (REBs). At the periodical structure, the field can be expanded into a series of spatial harmonics, which, in the case of shallow corrugations, represent paraxial wavebeams with mutual coupling described within the method of effective surface magnetic currents. We present the dispersion equation for the normal waves. Two limit cases can be recognized: in the first one, the frequency is far from the Bragg resonance and the wave propagation can be described within the impedance approximation with the field presented as a sum of the fundamental slow wave and its spatial harmonics. In the interaction with a rectilinear REB, this corresponds to the convective instability of particles’ synchronism with the fundamental (0th) or higher spatial harmonics (TWT regime), or the absolute instability in the case of synchronism with the −1st harmonic of the backward wave (BWO regime). In the latter case, at the frequencies close to the Bragg resonance, the field is presented as two antiparallel quasi-optical wavebeams, leading to the absolute instability used in the surface-wave oscillators operating in the π-mode regime. Based on the developed theory, we determine the main characteristics of relativistic Cherenkov amplifiers and oscillators with oversized electrodynamical systems. We demonstrate the prospects for the practical implementation of relativistic surface-wave devices in submillimeter wavebands.

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Section: Introductionmentioning

confidence: 99%

Quasi-Optical Theory of Relativistic Cherenkov Oscillators and Amplifiers with Oversized Electrodynamic Structures

et al. 2022

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“…Another variation is a resonance stub [23], which is also used as an electron prebuncher. Yet another is a Bragg reflector providing the desired radiation pattern of a BWO or selective feedback in a multimode interaction space of TWT [18]- [20], [24].…”

Section: Suppressing Feedback In a Twtmentioning

confidence: 99%

Controlled Amplification in a TWT Using the Guide Magnetic Field

Fuks

Goykhman²,

Kovalev³

et al. 2008

IEEE Trans. Plasma Sci.

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The interaction of the fast cyclotron wave of a linear electron beam guided by a magnetic field with a counterpropagating electromagnetic wave leads to the appearance of a stop-band over a wide range of the magnetic field near its resonance. Suppression of generation in backward wave oscillators and the resonant-cyclotron method of mode selection are based on this effect, termed "cyclotron absorption." In this paper, we analyze the possibility of controlling regenerative amplification in such oscillators as a traveling wave tube (TWT) by suppressing parasitic feedback using the guide magnetic field in the region of cyclotron absorption (RCA). Approaching the magnetic field to values that border this region, which contain thresholds of self-excitation, leads to a decrease in suppression of the reflected wave that is responsible for the positive feedback; in other words, this leads to an increase in gain. We illustrate amplification in the RCA using two approaches: the theory of stationary operation of a TWT accounting for the cyclotron resonance of electrons with a reflected wave, and particle-in-cell computer simulations.Index Terms-Cherenkov and cyclotron interactions, cyclotron absorption, cyclotron waves, positive feedback, regenerative amplification, traveling wave tube.

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“…A small number of centers results in the rise of the initial transverse velocities of the electrons in the beam, and deterioration of its uniformity and energy homogeneity. Enlargement of the e-beam cross section should facilitate the conditions for the long-pulse generation [6], when the growth of a transverse dimension of the beam becomes essential due to the cathode plasma expansion (the expansion velocity across the magnetic field lines is ∼10 6 cm/s) [5] as well. In Cherenkov microwave oscillators, where a thin tubular beam is used, a transverse expansion of the cathode plasma results in the deterioration of the terms of current transport through a slow-wave structure (SWS) and does not contribute to the conservation of the optimum conditions of the energy exchange throughout the duration of the current pulse [7].…”

Section: Introductionmentioning

confidence: 99%

<inline-formula> <tex-math notation="TeX">\(X\) </tex-math></inline-formula>-Band Relativistic Cherenkov Microwave Oscillator With Increased Cross-Sectional Electron Beam

Totmeninov

2014

IEEE Trans. Plasma Sci.

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Based on numerical simulation, a scheme of the X-band relativistic Cherenkov microwave oscillator with a hollow cylindrical increased cross-sectional electron beam transported by the external magnetic field is considered. For the electron energy of ∼0.5 MeV and electron beamwidth of ∼5 mm, an effective 100-ns-long pulse mode in a reduced magnetic field of 0.75 T has been calculated. Within the stationary stage of oscillation, the maximum simulated microwave power for the operating TM 01 mode was 630 MW that corresponded to the oscillator efficiency of 34% at the oscillation frequency of 10 GHz.

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Relativistic backward wave oscillator using a selective mode converter

Cited by 17 publications

References 0 publications

Quasi-Optical Theory of Relativistic Cherenkov Oscillators and Amplifiers with Oversized Electrodynamic Structures

Quasi-Optical Theory of Relativistic Cherenkov Oscillators and Amplifiers with Oversized Electrodynamic Structures

Controlled Amplification in a TWT Using the Guide Magnetic Field

<inline-formula> <tex-math notation="TeX">\(X\) </tex-math></inline-formula>-Band Relativistic Cherenkov Microwave Oscillator With Increased Cross-Sectional Electron Beam

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