Gas–plasma and superlattice free-electron lasers exploiting a medium with periodically modulated refractive index

Аполлонов, В. В.; Artemyev, A.I.; Федоров, М. В.; McIver, John K.; Shapiro, E. A.

doi:10.1017/s0263034600011599

Cited by 5 publications

(4 citation statements)

References 11 publications

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“…Thus we see that the presence of a dispersive medium inside of the undulator offers additional possibilities for generation of hard twisted photons with desired properties. We did not study in this paper the effect of a periodic modulation of the dielectric medium on the properties of radiation of twisted photons [22,58,65,71,77]. This will be the subject of our future research.…”

Section: Discussionmentioning

confidence: 94%

“…where M p is the proton mass in grams and n m is the particle number of the medium in 1 cm 3 . To run such an undulator in the FEL regime, more stringent conditions on the parameters of the particle beam and the dielectric medium must be imposed [13][14][15][16][17][18][19][20]22]. ⊥ /q ≈ 7.3 and K 2 /(qγ 2 ) ≈ 1.2 that means that the multiple scattering can be neglected.…”

Section: Undulatormentioning

confidence: 99%

“…Usually the chamber where the charged particles move in the undulator or the whole undulator are mounted in an ultra high vacuum. Nevertheless, there are theoretical and experimental works where the undulators and FELs filled with a dielectric medium are studied [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. The presence of a medium in the undulator degrades the properties of the electron beam evolving in it but, on the other hand, one may adjust the parameters of the beam and the medium in such a way that the undulator will produce the photons with larger energies and narrower spectral bands than the vacuum undulator for a given energy of electrons.…”

Section: Introductionmentioning

confidence: 99%

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Generation of twisted photons by undulators filled with dispersive medium

Bogdanov,

Kazinski,

Lazarenko

2020

Preprint

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The radiation of twisted photons by undulators filled with a homogeneous dielectric dispersive medium is considered. The general formulas for the average number of radiated twisted photons are obtained. The radiation of undulators in the dipole regime and the radiation of the helical and planar wigglers are studied in detail. It is shown that the selection rules for radiation of twisted photons established for undulators in a vacuum also holds for undulators filled with a dielectric medium. In the case of a medium with plasma permittivity the lower undulator harmonics do not form. This fact can be used for generation of twisted photons with nonzero orbital angular momentum on the lowest admissible harmonic. The use of the effect of inverse radiation polarization for generation of twisted photons with larger orbital angular momentum is described. The influence of the anomalous Doppler effect on the projection of the total angular momentum of radiated twisted photons is investigated. The parameters of the undulator and the charged particles are found such that the produced radiation, in particular, the Vavilov-Cherenkov radiation, is a pure source of twisted photons with definite nonzero orbital angular momentum. The developed theory is used to describe the radiation of twisted photons by beams of electrons and protons in the undulators filled with helium. We also consider the radiation of X-ray twisted photons by electrons in the undulator filled with xenon. The parameters are chosen so as to be achievable at the present experimental facilities.

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Section: Discussionmentioning

confidence: 94%

Section: Undulatormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Generation of twisted photons by undulators filled with dispersive medium

Bogdanov,

Kazinski,

Lazarenko

2020

Preprint

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“…Second, the electron bunching process can be enhanced by tuning the wave frequency close to the plasma frequency [7]. Third, a density depleted plasma channel provides strong radiation guiding [8,9]. Besides, the presence of plasma opens up the possibility of employing the plasma eigenmodes as a wiggler for the excitation of short wavelengths.…”

Section: Introductionmentioning

confidence: 99%

Electron trajectories and growth rates of the plasma wave pumped free-electron laser

Jafari

Jafarinia

Nilkar

et al. 2014

Plasma Phys. Control. Fusion

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A theory for a plasma wave wiggler has been described which employs the plasma whistler wave for producing laser radiation in a free-electron laser (FEL). While electromagnetically pumped FELs have been proven to be an effective means generating short wavelengths, practical difficulties occur in the design of these wigglers. For this reason, it is found that a plasma wave wiggler can be employed in concept with an electromagnetic wave wiggler due to both higher tunability and holding the focus of pump wave and e-beam over a significant distance to achieve a suitable amplification. Plasma in the presence of static magnetic field supports a plasma whistler wave. The plasma wiggler period can be tuned by varying the plasma density and/or ambient magnetic field. Electron trajectories have been analyzed using single particle dynamics and regimes of orbital stability have been demonstrated. A polynomial dispersion relation for electromagnetic and space-charge waves has then been derived, analytically. Numerical studies of the dispersion relation reveal that the growth rates are sensitive functions of the cyclotron frequency. It has been shown that by increasing the axial magnetic field strength (or cyclotron frequency), the growth rate for groups I and III orbits increases, while a growth decrement has been obtained for groups II and IV orbits.

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