2022, Grigorovich, D. A., Uryupin, S. A., Ovchinnikov, K. N., Урюпин, Сергей Александрович

2022, Vagin, K. Y., Mamontova, T. V., Uryupin, S. A., Мамонтова, Татьяна Вячеславовна, Урюпин, Сергей Александрович

2019, Vagin, K. Y., Mamontova, T. V., Uryupin, S. A., Мамонтова, Татьяна Вячеславовна, Урюпин, Сергей Александрович

© 2019In the regime of above-threshold ionization of gas atom in the field of laser radiation, plasma with photoelectron distribution consisting of peaks at discrete energy values is formed. It is shown that the number of longitudinal waves in such plasma coincides with the number of peaks in the distribution function. When peaks practically don't overlap, the dispersion law of each wave in the region of short waves is determined by electrons from the corresponding peak. In this case the phase and group velocities of the waves are close to the electron velocity, which corresponds to the peak maximum. It is possible to talk about such waves as an electronic sound, since the perturbations of the electron density mainly arise due to pressure perturbations. When the peaks are narrow, but having a finite width, the Cherenkov damping of waves is exponentially small. Numerical calculations the dispersion laws for of the two and four waves in photoionized xenon plasma, in which the electron distribution function consists of two or four narrow peaks are given.

2019, Danilov, P. A., Rudenko, A. A., Ionin, A. A., Umanskaya, S. F., Kudryashov, S. I., Bezhanov, S. G., Uryupin, S. A., Бежанов, Станислав Георгиевич, Урюпин, Сергей Александрович

© 2019, Pleiades Publishing, Inc.The transmission of femtosecond laser pulses of the near-infrared range (wavelength of 1030 nm) through nanocrystalline gold films with a variable thickness (15–90 nm) has been experimentally studied for various intensities of laser radiation in the range of 1–10 TW/cm2. A dip in the transmission coefficient at the wave-length of pump pulses at moderate radiation intensities is due to two-photon transitions from d bands with a high density of states to s and p bands with a low density of states and their saturation at higher intensities. The cross section is estimated for two-photon absorption in gold films enhanced by plasmon resonance of gold nanocrystallites at the wavelength of the second harmonic of exciting radiation, which is compared to values for gold films and various plasmon nanostructures known for other spectral ranges.

2025, ШЕЛКОВОЙ, А. А., УРЮПИН, С. А., Урюпин, Сергей Александрович

Описано торможение разреженного пучка ионов в плазме с ионно-звуковой турбулентностью, возникающей в сильном электрическом поле. При торможении вдоль или поперёк оси симметрии распределения ионно-звуковых волн по волновым числам получены зависимости компонент скорости ионов пучка от времени или координаты для различной напряженности электрического поля. Найдены времена и длины торможения пучка вдоль и поперек электрического поля. Торможение прекращается, когда скорость ионов пучка близка к скорости ионного звука.

2020, Malishevskii, A. S., Uryupin, S. A., Урюпин, Сергей Александрович

© 2020 Elsevier B.V.Josephson sandwich is considered, along which the radiating chain of vortices travels. Uniform movement of the chain is supported by bias current. The current-voltage characteristic connecting this current with the voltage at the Josephson junction is found. It is shown that when the current increases, generation of electromagnetic waves with frequency weakly dependent on the current is possible.

2019, Danilov, E. A., Uryupin, S. A., Урюпин, Сергей Александрович

The action of an s-polarised femtosecond laser pulse is found to result in nonlinear currents in a metal film, which arise due to the nonuniform heating of the conduction electrons and under the influence of the drag force. The Fourier transforms of a low-frequency magnetic field generated by nonlinear currents are calculated. It is shown that when the film thickness is less than the scale of the low-frequency field nonuniformity, the amplitude of the tera-hertz signal increases in inverse proportion to the film thickness. If the thickness of the film is less than the depth of the skin layer at the laser frequency, the low-frequency signal is amplified inversely proportional to the square of the film thickness.

2021, Grishkov, V. E., Ovchinnikov, K. N., Uryupin, S. A., Урюпин, Сергей Александрович

© 2021, Springer Science+Business Media, LLC, part of Springer Nature.We establish the conditions under which collisions of electrons with ions affect the generation of terahertz radiation at normal incidence of a laser pulse on a dense plasma in a constant magnetic field. If during the time of exposure to the laser pulse, the number of collisions of electrons occurred is not small, then the amplitude of generated magnetic field decreases, the shape of the generated pulse changes, and the total energy of terahertz radiation decreases. The influence of collisions on the generation of terahertz radiation manifests itself in a relatively weak magnetic field, when the electron cyclotron frequency is lower than the plasma frequency.

2019, Smirnov, N. A., Gakovic, B., Milovanovic, D., Ionin, A. A., Kudryashov, S. I., Bezhanov, S. G., Uryupin, S. A., Бежанов, Станислав Георгиевич, Урюпин, Сергей Александрович

© 2019, Pleiades Publishing, Inc.The dependences of the depth of single-pulse ablation of the steel surface on the energy density of ultrashort laser pulses (0.3–12 ps) with a wavelength of 515 nm have the form different from the usual logarithmic one for linear absorption of radiation. Since the density of states of free conduction electrons in the s band is low, and the d band of strongly bound electrons with a high density of states is located around the Fermi level, these dependences have been approximated within the two-photon absorption model. The two-photon absorption coefficient increases almost linearly with the duration of laser pulses, which indicates the saturation of absorption and allows estimating the corresponding parameters of the electronic subsystem.

2021, Vagin, K. Y., Mamontova, T. V., Uryupin, S. A., Мамонтова, Татьяна Вячеславовна, Урюпин, Сергей Александрович

©2021 American Physical SocietyThe interaction of electromagnetic radiation with inhomogeneous plasma formed by multiphoton ionization of inert gas atoms has been studied. In high-frequency and normal skin effects modes the field structure in plasma is described and reflection and absorption coefficients are found. It is shown that as the thickness of the plasma region, in which the photoelectron density grows linearly, increases, both the depth of field penetration and the absorption coefficient increase, too. It is found that, due to the Ramzauer-Townsend effect, there is a relative increase in the effective frequency of photoelectron collisions with atoms, which is accompanied by a significant increase in the absorption coefficient.