Saturation mechanism in a two-stream free-electron laser

Mahdizadeh, N.

doi:10.1017/s0022377815001427

Cited by 9 publications

(12 citation statements)

References 17 publications

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“…Then they form joint twovelocity helical electron beam 5. Electromagnetic signal 11 ,k  (in the form of an amplified electromagnetic wave) is directed in the same input of the first pumping system 4. Two-velocity electron beam 5 is weakdensity-modulated as a result of the nonlinear parametric interaction of the electromagnetic wave The two-stream instability develops in electron beam 5 within transit section 6.…”

Section: Model Basic Equationsmentioning

confidence: 99%

“…Two-velocity electron beam 5 is weakdensity-modulated as a result of the nonlinear parametric interaction of the electromagnetic wave The two-stream instability develops in electron beam 5 within transit section 6. Amplification maximum of the longitudinal electron waves in this case attains for the waves with some optimal frequency opt  (9) [1,8,[11][12][13]. The key point of the discussed design is that the modulation frequency 3  is much smaller than the optimal frequency opt  , at which SCW has maximal growth increment due to the two-stream instability.…”

Section: Model Basic Equationsmentioning

confidence: 99%

“…plural parametric resonant interactions take place. Such plural interactions are accounted in the system (11), (13). Thus, due to the linear dispersion relation plural parametric resonant interactions between SCW harmonics are realized in the system on the condition  <  cr .…”

Section: -5mentioning

confidence: 99%

“…Owing to the two-stream instability, the two-stream superheterodyne free-electron lasers (TSFELs) are characterized by exclusively high amplification properties in millimeter-infrared wavelength band [1][2][3][4][5][6][7][8][9][10][11]. However, single-section TSFEL amplifiers have a pronounced tendency to self-excitation due to extremely high amplification level.…”

Section: Introductionmentioning

confidence: 99%

“…In the majority of works devoted to TSFEL klystrons and TSFEL in general, only monochromatic operation modes are investigated. In such modes the space charge wave (SCW) is excited on the frequency having maximal amplification due to the two-stream instability [1][2][3][4][5][6][7][8][9][10][11]. Lately, there are also works investigating multiharmonic operation modes of TSFELs [1,12,13].…”

Section: Introductionmentioning

confidence: 99%

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Space Charge Wave with Broad Frequency Spectrum Formation in Transit Section of Klystron-type Two-stream FEL with Helical Electron Beam

Lysenko¹,

Volk²,

Oleksiienko³

et al. 2019

J. Nano- Electron. Phys.

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In the cubic non-linear approximation framework, the analysis of space charge wave formation with a wide frequency spectrum in helical two-velocity electron beams was performed. It was shown that the formation of a space charge wave with wide frequency spectrum in this kind of beams occurs on condition that the wave first harmonic frequency is much less than the two-stream instability critical frequency. We demonstrated that due to the linearity of the growing space charge wave dispersion characteristic, the condition of the three-wave parametric resonant interactions in helical two-stream relativistic electron beam fulfills for a significant number of such wave's harmonics which frequencies are less than the critical frequency. Due to these resonances, the excitation of multiharmonic space charge wave occurs. This wave is amplified due to both the three-wave parametric resonances and the two-stream instability mechanism. As a result, the multiharmonic space charge wave forms, and its spectrum width is defined by the 1 st harmonic frequency and the two-stream instability critical frequency. It is demonstrated that the frequency spectrum width of the multiharmonic space charge wave increases with the increase of the electrons input angle with respect to the longitudinal focusing magnetic field and it exceeds the frequency spectrum width of such waves in straight electron beams. It is also found out that the space charge wave saturation length in a helical electron beam is two and more times less than in straight electron beams. Therefore, the devices using two-stream helical relativistic electron beams would have less longitudinal dimensions. We proposed to use helical two-stream relativistic electron beams in multiharmonic two-stream superheterodyne freeelectron lasers in order to increase the frequency spectrum width and to decrease the device's longitudinal dimensions compared with devices using straight electron beams.

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Section: Model Basic Equationsmentioning

confidence: 99%

Section: Model Basic Equationsmentioning

confidence: 99%

Section: -5mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Space Charge Wave with Broad Frequency Spectrum Formation in Transit Section of Klystron-type Two-stream FEL with Helical Electron Beam

Lysenko¹,

Volk²,

Oleksiienko³

et al. 2019

J. Nano- Electron. Phys.

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Forming of Space Charge Wave with Broad Frequency Spectrum in Helical Relativistic Two-Stream Electron Beams

Lysenko

Volk

Serozhko

et al. 2017

Chinese Phys. Lett.

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We elaborate a quadratic nonlinear theory of plural interactions of growing space charge wave (SCW) harmonics during the development of the two-stream instability in helical relativistic electron beams. It is found that in helical two-stream electron beams the growth rate of the two-stream instability increases with the beam entrance angle. An SCW with the broad frequency spectrum, in which higher harmonics have higher amplitudes, forms when the frequency of the first SCW harmonic is much less than the critical frequency of the two-stream instability. For helical electron beams the spectrum expands with the increase of the beam entrance angle. Moreover, we obtain that utilizing helical electron beams in multiharmonic two-stream superheterodyne free-electron lasers leads to the improvement of their amplification characteristics, the frequency spectrum broadening in multiharmonic signal generation mode, and the reduction of the overall system dimensions.

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The Saturation Mechanism in a two-stream free-electron laser based upon a rectangular hybrid wiggler

2023

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Presented in this paper is a one-dimensional nonlinear simulation of a square hybrid two-stream free electron laser (TSFEL) consisting of an axial magnetic field guide. It is supposed that the two cold relativistic electron beams differ in energy, while the electron beam's self-fields, and radiation wave slippage relative to electron beams are neglected. A set of differential equations of the first order of coupled nonlinearity, obtained from the combination of Maxwell's equations and Lorentz's equations, can be numerically solved using a Rang-Kutta algorithm of fourth order based on slowly varying amplitudes and wavenumbers approximation. According to the results of the calculations, the increase in the axial magnetic field will result in the efficiency in group I orbits increasing while the saturation length decreases. The results for group II orbits are different from those of group I, such that the efficiency decreases with the increasing axial magnetic field. There is, however, an increase in saturation length. Furthermore, it is found that prebunching significantly reduces the length of saturation. A comparison of radiation saturation in an FEL and a TSFEL indicates that a TSFEL has a higher efficiency than an FEL. In contrast, the TSFEL has shorter saturation lengths.

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Saturation mechanism in a two-stream free-electron laser

Cited by 9 publications

References 17 publications

Space Charge Wave with Broad Frequency Spectrum Formation in Transit Section of Klystron-type Two-stream FEL with Helical Electron Beam

Space Charge Wave with Broad Frequency Spectrum Formation in Transit Section of Klystron-type Two-stream FEL with Helical Electron Beam

Forming of Space Charge Wave with Broad Frequency Spectrum in Helical Relativistic Two-Stream Electron Beams

The Saturation Mechanism in a two-stream free-electron laser based upon a rectangular hybrid wiggler

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