2022, Sergeeva, D. Y., Garaev, D. I., Tishchenko, A. A., Сергеева, Дарья Юрьевна, Гараев, Дамир Ильдарович, Тищенко, Алексей Александрович

2024, Garaev, D. I., Sergeeva, D. Y., Tishchenko, A. A., Гараев, Дамир Ильдарович, Сергеева, Дарья Юрьевна, Тищенко, Алексей Александрович

2019, Tishchenko, A. A., Sergeeva, D. Y., Тищенко, Алексей Александрович, Сергеева, Дарья Юрьевна

© 2019, Pleiades Publishing, Inc.It has been shown that polarization radiation of charged particle beams generally includes an incoherent form factor caused by a finite transverse size of a beam. Consequently, a widespread opinion that the form factor characterizes only coherent radiation of charge particle bunches is generally invalid. The reason for the existence of incoherent form factor is the interaction of charged particles with the target edge in the direction perpendicular to their trajectory. The incoherent form factor exists for diffraction radiation, Smith-Purcell radiation, and other types of polarization radiation in the case of transversely limited targets: transition radiation, parametric X-ray radiation, and Cherenkov radiation. It has been shown that the difference of the incoherent form factor from unity increases with a decrease in the ratio of the impact parameter to the transverse size of the bunch. Furthermore, it has been shown that the transverse part of the coherent form factor differs from unity to the same extent as the incoherent form factor.

2020, Tishchenko, A. A., Sergeeva, D. Yu., Garaev, D. I., Тищенко, Алексей Александрович, Сергеева, Дарья Юрьевна, Гараев, Дамир Ильдарович

© Санкт-Петербургский государственный университет, 2020In this paper we investigate analytically polarization radiation excited due to interaction of an electron with a cluster of coupled subwavelength particles. The results are valid both for nonrelativistic and for relativistic charged particles. The expression for the Fourier image of radiation field has been obtained, which allows direct calculating spectral and angular density of the radiated energy. In general case, to find the radiation field with taking into account the interaction between particles, it is necessary to solve a system of N! self-consistent tensor equations, where N is the number of particles in the cluster. We suggest the algorithm for reducing the system of N! equations to N equations. The reduction in the number of equations is achieved through the calculation of the fields at the each point in which the dipole moment is, rather than through calculation of the fields from the every source. This facilitates considerably the finding solutions in problems of radiation for the clusters of particles.

2020, Sergeeva, D. Y., Tishchenko, A. A., Сергеева, Дарья Юрьевна, Тищенко, Алексей Александрович

© 2020, Pleiades Publishing, Ltd.Abstract: The study considers diffraction radiation, which is excited when an electron moves near a cluster of two interacting subwavelength particles. The interaction is manifested in the fact that the radiation field from each particle is determined not only by the external field of the electron, but also by the field of the neighboring particle. Based on the obtained expressions for the radiation field, the function of cluster polarizability is determined. It characterizes the cluster response to the field of the electron as a whole. It is interesting that the obtained response function of the cluster to an external field, even in the framework of linear theory, generally depends on the external field itself.

2015, Tishchenko, A. A., Sergeeva, D. Yu., Strikhanov, M. N., Стриханов, Михаил Николаевич, Тищенко, Алексей Александрович, Сергеева, Дарья Юрьевна

Transition radiation (TR) and Diffraction radiation (DR) can be interpreted as a result of action of a charged particle upon a target. These types of radiation have similar nature and arise due to the dynamic polarization of the target material by the Coulomb field of the charged particles. TR is generated when the beam crosses the media surface; DR is generated when the beam moves above the inhomogeneous medium, e.g. above the side of a slab.

2019, Tishchenko, A. A., Sergeeva, D. Y., Тищенко, Алексей Александрович, Сергеева, Дарья Юрьевна

In this work we construct the first-principles theory for the near-field resonances arising in the system of two different coupled nanoparticles excited by the external field. The obtained expressions are valid for an arbitrary external field; the detailed analysis is performed for the case of a fast electron passing by. The energy of electron is arbitrary, so the results are valid both for relativistic and nonrelativistic electrons. We have obtained rigorous analytical solution for the radiation field and for distribution of radiation over angles and frequencies. The effect of interaction between the single particles manifests itself very distinctly in conditions of resonance, resulting in a spectral shift of the radiation maximum, significant increase of its altitude, and, interestingly, in clear oscillations in radiation intensity not only when the particles are very close to each other, but even when the distance between the particles exceeds considerably their sizes. It attests to the strong influence of interaction on the radiation processes in a system of coupling particles.

2023, Garaev, D. I., Sergeeva, D. Y., Tishchenko, A. A., Гараев, Дамир Ильдарович, Сергеева, Дарья Юрьевна, Тищенко, Алексей Александрович

2019, Savchenko, A. A., Sergeeva, D. Yu., Tishchenko, A. A., Strikhanov, M. N., Савченко, Александр Алексеевич, Сергеева, Дарья Юрьевна, Тищенко, Алексей Александрович, Стриханов, Михаил Николаевич

In this work, we construct for the first time the theory of small-angle transition radiation from multilayered structures. The theoretically obtained spectral and angular distributions of radiated photons are compared with those predicted by GEANT4, a very popular package used today for numerical simulation of different physical processes. We demonstrate that, while spectral distributions ideally coincide, the angular ones differ. We argue that transition radiation from the multilayered structure must contain sharp spikes having the interference nature and caused by the effect of merging two maximum frequencies in dispersive media, and thus GEANT4 needs improving in this respect. The transition radiation theory developed here for the small-angle case can play a vital part for the possible future Small Angle Spectrometer at the LHC, other experiments of this kind, and detectors for hadrons of the tera-electron-volt energy range.

2023, Tishchenko, A. A., Sergeeva, D. Yu., Garaev, D. I., Гараев, Дамир Ильдарович, Сергеева, Дарья Юрьевна, Тищенко, Алексей Александрович

Terahertz radiation sources based on the radiation of electrons in external fi elds attracts the attention of researches due to the huge energy stored in relativistic electron beams. Even a little part of this energy, being radiated, makes it possible to produce powerful radiation in various parts of spectrum, including terahertz one, which is exploited in gyrotrons, magnetrons, orotrons etc. Besides its customary applications in powerful radiation sources and in non-destructive diagnostics of relativistic electron beams, the last decade SPR is intensively investigated for more exotic structures, like plasmonic crystals [1-3], graphene nanoscale gratings [4, 5], metasurfaces [6, 7]. These novel structures are widely investigated today due to their tunability, opportunity to tailor the properties of the surfaces, which results in developing novel modulators [8] and fi lters [9] — the key elements in applications of modern optics.