V.А. Eremenko1, N.I. Manaenkova2

1,2 Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation (Moscow, Russia)

1 eremenko@izmiran.ru, 2 nat_man@mail.ru

The article presents the results of studies of the interaction of concentrated wave fields in nonlinear media. The problem of nonlinear interaction of wave fields arises in many physical systems, including the propagation of powerful radio emission in the ionospheric plasma. Nonlinear effects can demonstrate themselves as self-action of the wave and as interaction of concentrated waves with each other. The most frequently used model of nonlinearity is the so-called Kerr nonlinearity, where the nonlinear perturbation of the dielectric permittivity is proportional to the square of the modulus of the wave amplitude. This assumption allows us to describe the main effects arising from the nonlinear interaction of radiation with the propagation environment. However, this approach has certain limitations. It is obvious that nonlinear effects do not occur while the wave field power is insufficient. However, as soon as the wave amplitude value overcomes a certain threshold value, a «breakdown» of the medium occurs and a nonlinear dependence of the dielectric permittivity on the wave field amplitude appears. In addition, in many media, with a significant increase in the power of electromagnetic radiation, the effect of saturation of the electron density disturbance occurs, which leads to a noticeable weakening of the nonlinear effect of the wave field on the propagation environment. In this paper, we consider the problem of nonlinear interaction of wave fields under conditions of saturable and threshold nonlinearity. The possibility of the existence of concentrated wave fields under these conditions is shown. A significant difference between the interaction of such fields and the interaction of classical solitons is revealed. In the case of saturable nonlinearity, the interaction of beams is closer to the interaction of standard solitons, although the interaction region increases noticeably with an increase in the saturation parameter. Under conditions of threshold nonlinearity, beams can merge into a single conglomerate with an increased amplitude. With repeated interaction, the amplitude will continue to increase, but not to infinity, because with increasing amplitude, the beams stop sticking together. It is obviously, that with a significant excess of the nonlinearity threshold, the threshold solitons almost restore their structure after interaction– the amplitude of each beam approaches the original one.

Eremenko V.А., Manaenkova N.I. Features of the interaction of solitons under different types of nonlinearity. Achievements of modern radioelectronics. 2024. V. 78. № 11. P. 28–33. DOI: https://doi.org/10.18127/j20700784-202411-03 [in Russian]

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