Interaction of space-charge waves in an electron beam with electromagnetic waves in a longitudinal magnetic field

The effect of space charge on the interaction between an electron beam and an electromagnetic wave in a longitudinal magnetic field has been considered. The equations describing the interaction processes have been formulated within the two-dimensional linear theory and solved using the dispersion-equation approach and the successive approximation method.     

Generation and amplification of electromagnetic waves by an annular electron beam in a radial electric field in free space

Mechanisms for the generation and amplification of electromagnetic waves by a thin-walled annular beam of electrons rotating in a radial electric field in free space are studied theoretically. It is shown that electromagnetic waves can be generated and amplified under the Cherenkov resonance conditions. The frequencies and growth rates of the generated waves are determined, and the propagation characteristics and amplification coefficients of the amplified waves are found.     

Possibility of the charge density modulation of an electron bunch in the electromagnetic wave field

We consider the problem of modulation of the electron density in a linear bunch after its interaction with a linearly polarized, monochromatic electromagnetic wave, as well as an opportunity to observe this effect. It is shown that one can achieve significant values of the modulation depth at high intensities of the electromagnetic wave.     

External electric field induced modulation instability of an electromagnetic beam in two-photon photorefractive materials

The modulation instability of a broad electromagnetic beam in a biased two-photon photovoltaic photorefractive material, due to two-photon-photorefractive effect has been investigated. The one-dimensional modulation instability growth rate has been estimated under the linear stability framework. The behavior of the gain spectrum is different in low and high power regions. It has been predicted that, with the application of external electric field, it is possible to initiate and control growth of the instability in those media, where modulation instability was hitherto prohibited. The influence of different system parameters on the instability growth rate has been examined.     

Interaction of surface electromagnetic waves with an electron beam moving along the interface between metamaterials

Excitation of surface polaritons by an infinitely narrow electron beam propagating in the vacuum gap between a metal-like medium and an artificial dielectric with a negative permeability is studied theoretically. A dispersion relation is derived for the waves excited by the beam for an arbitrary thickness of the gap. The possibility of the emergence of absolute instability is demonstrated for an infinitely narrow vacuum gap, and the corresponding increments are calculated with allowance for small dissipative losses.     

Instability of plasma waves in an electromagnetic field

Summary In the presence of a weak laser field the plasma scattering by electrons is discussed.

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Riassunto In presenza di un campo laser debole, si discute la diffusione del plasma mediante elettroni.

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Резюме В присутствии слабого лазерного поля обсуждается рассеяние плазмы на электронах.

     

Parametric excitation of electromagnetic and surface plasma waves of a ribbon electron beam in a periodic magnetic field

Rostov State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 33, No. 4, pp. 488–496, April, 1990.     

Effective mass of an electron in an electromagnetic field

The effective-mass formalism is shown capable to describe the fully relativistic motion of an electron in a strong, locally plane, electromagnetic wave, determining the drift caused by the wave inhomogeneity and by additional weaker fields. The limits of this approach are discussed, in connection with the occurrence of resonances.     

Green's function of an electron in an external electromagnetic field

New field-theoretical representations are obtained for Green's function of an electron in an external electromagnetic field, making it possible to simplify its calculation substantially.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 33–37, February, 1982.     

Quantum processes in an intense electromagnetic field. II

An approach is suggested to the treatment of processes in an external electromagnetic field that generates real pairs. The interaction with the field is allowed for exactly by means of the solutions of the Dirac equation. Processes of arbitrary order in the electron-photon interaction are considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 86–92, October, 1976.In conclusion the author wishes to thank V. G. Bagrov and Sh. M. Shvartsman for useful discussions and critical comments.     

Quantum processes in an intense electromagnetic field. I

The Furry approach for arbitrary external electromagnetic fields that do not generate real pairs is considered. Problems of the existence of a stable vacuum in the field are discussed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 81–86, October, 1976.The author is grateful to F. A. Berezin for refinement of the theorems used in this work and to A. A. Grib, S. G. Mamaev, and V. M. Mostepanenko for valuable critical comments.     

Nonlinear theory of scattering of linearly polarized electromagnetic waves by unmagnetized electron beam

The nonlinear dynamics of scattering of linearly polarized electromagnetic waves by an unmagnetized beam of nonrelativistic electrons is studied. General nonlinear equations are derived and linear scattering regimes are analyzed. For the case of high-density beams, the general nonlinear equations are reduced to a system containing only cubic nonlinearities. Analytic expressions are provided for the amplitudes of interacting waves and for typical process-development times.     

Electron in the field of two plane electromagnetic waves and an inhomogeneous electric field

This work examines the motion of an electron in an electromagnetic field consisting of the field of two plane electromagnetic waves of different frequencies ₁, ₂ and an electric fieldE'=(E₀ + E₃cos₃)e₃. The method of separation of variables is used to construct the solution of the Hamilton-Jacobi equation. The motion of the electron in the external electromagnetic field is described by those solutions of the Dirac equation coinciding with the eigenfunctions of the commutating operators.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 89–94, February, 1982.