Cherenkov superradiance with a peak power higher than electron flow power

Elchaninov, A. A.; Korovin, S. D.; Rostov, V. V.; Pegel, I. V.; Mesyats, G.; Yalandin, M. I.; Ginzburg, N. S.

doi:10.1134/1.1577754

Cited by 48 publications

(28 citation statements)

References 6 publications

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“…Moreover, the instantaneous efficiency of the generation of such rf pulse (the ratio of the rf pulse peak power to the power of the electron beam, which is also called "conversion factor") may exceed 100%. This fact has been observed in experiments [6,8], and it does not contradict the energy conservation law. Actually, the process of the emission of the SR rf pulse has a principally nonstationary character, namely, a relatively short backward (counter-propagated) rf pulse is formed in the process of its motion via a significantly longer electronbeam pulse.…”

Section: Introductionsupporting

confidence: 72%

“…An effective method for generation of powerful pulses of coherent microwave electromagnetic radiation is the use of the so-called super-radiance (SR) regime of operation of a Cherenkov backward-wave oscillator (BWO) [1][2][3][4][5][6][7][8][9]. It is well-known that if the length of the electron-wave interaction region of a BWO significantly exceeds the starting threshold, then the transient process of excitation of the oscillator includes excitation of a short powerful rf pulse [1].…”

Section: Introductionmentioning

confidence: 99%

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Generation of Super-Radiance rf Pulses in a Sectioned Backward-Wave Oscillator

Savilov¹

2009

TOPPJ

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Section: Introductionsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Generation of Super-Radiance rf Pulses in a Sectioned Backward-Wave Oscillator

Savilov¹

2009

TOPPJ

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“…The pulse-beam interaction time can be much longer than the pulse duration. This makes it possible to obtain an output microwave power that is several times higher than the electron beam power [2,3].…”

mentioning

confidence: 99%

“…Recently such pulsed generation regimes have actively been studied both theoretically and experimentally [1][2][3][4].…”

mentioning

confidence: 99%

Generation of high-power nanosecond pulses in a relativistic backward-wave oscillator in the regime of spatial accumulation of energy

Afanasyev

Bykov

Gubanov

et al. 2006

Radiophys Quantum Electron

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We study the generation of electromagnetic pulses with a carrier frequency of 3.7 GHz in a relativistic backward-wave oscillator with a long slow-wave system in the superradiance regime of super-radiation for a magnetic induction of 0.2 T (below the cyclotron resonance). To decrease transverse velocities of the electrons, we use decompression of a hollow electron beam. Decompression in combination with a sharp leading edge of the high-voltage pulse (460 kV) applied to the explosive-emission cathode are used for increasing the cathode lifetime and improving the azimuthal uniformity of the beam. As a result, the achieved peak power of the microwave radiation amounts to 800 MW for a pulse duration of 2.5 ns and a repetition rate of 100 Hz. The uninterrupted operation in such a regime determined by the lifetime of the explosive-emission cathode is increased up to 10 5 -10 6 pulses. The efficiency of conversion of the electron-beam power into the electromagnetic-wave power is increased up to 50%, The possibility of locking the electromagnetic oscillations phase by a sharp edge of the high-voltage pulse at the cathode was observed for the first time in such a relativistic generator.As is known, a short microwave pulse with a duration of several microwave periods and power significantly exceeding the radiation power in the stationary regime can be formed in a relativistic backwardwave oscillator. Recently such pulsed generation regimes have actively been studied both theoretically and experimentally [1][2][3][4].The duration of a microwave pulse is inversely proportional to the growth rate of the absolute instability in the beam-backward wave system [1] and can be about 10 periods of the microwave field for typical parameters of high-current beams:where C is the generalized amplification parameter (Pierce parameter), Z is the coupling impedance, ω is the angular frequency of the wave, e and m are the electron charge and mass, respectively, c is the velocity of light, V 0 is the velocity of electrons at the input of the slow-wave system, γ 0 is the relativistic Lorentz factor for the electrons, V gr is the group velocity of the wave, k = 2π/λ is the wave number, λ is the wavelength in free space, I b is the beam current, N s is the wave norm, and E z,−1 is the longitudinal component of the filed of the (−1)st spatial harmonic of the backward wave in a periodic corrugated waveguide. * anton@lfe.hcei.tsc.ru † Deceased.Institute of High-Current Electronics of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia.

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“…The studies of the superradiance effects of short electron bunches [1][2][3] has recently generated interest in analysis of the nonstationary processes in the electron-beam -backward-wave system for large reduced lengths of the interaction space. It was noted in the numerical simulation that the field distribution at the initial linear stage of interaction has a characteristic maximum near the collector end of the system.…”

mentioning

confidence: 99%

Absolute-instability growth rates and eigenmode structures in the electron-beam—backward-wave system with large excesses over the generation threshold

Zotova

Sergeev

2007

Radiophys Quantum Electron

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538.566We study the eigenmode structures with large excesses over the generation threshold in the electron-beam -backward-wave system in terms of the linear theory. It is shown that with increase in the length of the interaction space, the field maximum of both the fundamental and the higher-order modes shifts toward the collector end of the system. Asymptotic expressions for the growth rates, frequencies and spatial structures of the eigenmodes are obtained in the specified limiting case. When a superradiance pulse is generated in the system, a spatial field structure coinciding with the structure of the fundamental modes with a characteristic maximum near the collector end of the system is formed at the initial stage of interaction.1. The studies of the superradiance effects of short electron bunches [1-3] has recently generated interest in analysis of the nonstationary processes in the electron-beam -backward-wave system for large reduced lengths of the interaction space. It was noted in the numerical simulation that the field distribution at the initial linear stage of interaction has a characteristic maximum near the collector end of the system. As the wave propagates further upstream of the electron beam, the mentioned field distribution gives rise to a superradiance pulse at the cathode end of the system. In this relation, it is interesting to study the linear eigenmodes of this system with large excesses over the generation threshold. It should be mentioned that in most papers devoted to the theory of backward-wave oscillators (BWOs), the eigenmodes are considered in terms of stationary nonlinear theory [4][5][6]. For such modes, the field maximum is near the cathode end of the system for any length of the interaction space. It will be shown in the present paper that for the modes calculated within the framework of nonstationary linear theory, a structure with the maximum near the cathode end takes place only with small excesses over the generation threshold. As the length of the interaction space increases, the field maximum of both the fundamental and the higher-order modes shifts toward the collector end of the system. We succeed in analytically calculating the growth rates and eigenfrequencies of the modes, which determine the initial field distribution, in the specified limit.2. Consider interaction between an electron beam and an electromagnetic wave, whose group velocity is opposite to the electron direction, within the framework of the simplest one-dimensional nonstationary model [7]. In the laboratory reference frame, the linear stage of interaction in such a system can be described on the basis of the following system of equations:where z is the dimensionless (normalized to the Pierce parameter) longitudinal coordinate, t is the dimensionless time, and a and J are slowly varied amplitudes of the electromagnetic wave and the high-frequency

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Cherenkov superradiance with a peak power higher than electron flow power

Cited by 48 publications

References 6 publications

Generation of Super-Radiance rf Pulses in a Sectioned Backward-Wave Oscillator

Generation of Super-Radiance rf Pulses in a Sectioned Backward-Wave Oscillator

Generation of high-power nanosecond pulses in a relativistic backward-wave oscillator in the regime of spatial accumulation of energy

Absolute-instability growth rates and eigenmode structures in the electron-beam—backward-wave system with large excesses over the generation threshold

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