Relaxation of a relativistic electron beam in plasma in the trapping regime

A model for collective relaxation of high-power relativistic electron beams in plasmas is proposed, which describes beam-plasma interaction in the regime when amplitudes of unstable waves are large enough to trap beam electrons. The model predicts profiles of energy release along the plasma column in a good quantitative agreement with experimental measurements.Запропоновано модель колективної релаксації потужного релятивістського електронного пучка, яка описує взаємодію пучка з плазмою в режимі, при якому енергія нестійких коливань виявляється достатньої для захоплення електронів пучка. Модель передбачає профілі енерговиділення пучка в плазмі по довжині установки, які знаходяться в гарній кількісній згоді з експериментальними даними.Предложена модель коллективной релаксации мощного релятивистского электронного пучка, описывающая взаимодействие пучка с плазмой в режиме, при котором энергия неустойчивых колебаний оказывается достаточной для захвата электронов пучка. Модель предсказывает профили энерговыделения пучка в плазме по длине установки, которые находятся в хорошем количественном согласии с экспериментальными данными

Hybrid Tamm-cavity modes in photonic crystal with resonant nanocomposite defect layer

Hybrid optical modes in a one-dimensional photonic crystal with a resonant nanocomposite defect bounded by a metallic layer are studied. The nanocomposite consists of spherical metallic constituents, that are distributed in a dielectric matrix. Transmittance, reflectance, and absorbance spectra of this structure, which is shined by light with normal incidence, are calculated. The possibility of control of the hybrid modes spectral characteristics by changing the thickness of the layer adjacent to the metal, the number of layers, and the nanocomposite filling factor is shown.This research was funded by the Russian Foundation for Basic Research, Government of Krasnoyarsk Territory, Krasnoyarsk Region Science and Technology Support Fund to the research Project No 18-42-243025

Long-lived magnetoexcitons in 2D-fermion system

The paper addresses the experimental technique that, when applied to a 2D-electron system in the integer quantum Hall regime with filling factor ν = 2 (the Hall insulating state), allows resonant excitation of magnetoexcitons, their detection, control of an ensemble of long-lived triplet excitons and investigation of their radiationless decay related to exciton spin relaxation into the ground state. The technique proposed enables independent control of photoexcited electrons and Fermi-holes using photoinduced resonance reflection spectra as well as estimate with a reasonable degree of accuracy the resulting density of photoinduced electron-hole pairs bound into magnetoexcitons. The mere existence of triplet excitons was directly established by inelastic light scattering spectra which were analyzed to determine the value of singlet-triplet exciton splitting. It was found that the lifetimes of triplet excitons conditioned by electron spin relaxation in highly perfect GaAs/AlGaAs heterostructures with highly mobile 2D electrons are extremely long exceeding 100  μs at T < 1 K. The paper presents a qualitative explanation of the long-spin relaxation lifetimes which are unprecedented for translation-invariant 2D systems. This enabled us to create sufficiently high concentrations of triplet magnetoexcitons, electrically neutral excitations following Bose–Einstein statistics, in a Fermi electron system and investigate their collective properties. At sufficiently high densities of triplet magnetoexcitons and low temperatures, T < 1 K, the degenerate magnetofermionic system exhibits condensation of the triplet magnetoexcitons into a qualitatively new collective state with unusual properties which occurs in the space of generalized moments (magnetic translation vectors). The occurrence of a condensed phase is accompanied with a significant decrease in the viscosity of the photoexcited system, which is responsible for electron spin transport at macroscopic distances, as well as with the effects of threshold enhancement of the system response to the external action of the electromagnetic field and emergence of a new intensive radiative recombination channel

Research of the thermal desorption processes in oxide mixtures at laser effect

To investigate the physical-chemical processes occurring during the heating stage of spent nuclear fuel magneto plasma reprocessing a study of thermal desorption of oxides and oxide mixtures as SNF simulators under the influence of stationary laser radiation are being studied. Preliminary experiments were carried out. X-ray diffraction and energy dispersive X-ray microanalysis of the film deposited on the substrate after laser influence on a mixture of B₂O₃/ZrO₂ oxides have been performed.Для вивчення фізико-хімічних процесів, що відбуваються на стадії нагріву магнітоплазмової переробки відпрацьованого ядерного палива (ВЯП), проводиться дослідження процесів термодесорбції оксидів і оксидних сумішей - імітаторів ВЯП при впливі стаціонарного лазерного випромінювання. Проведено попередні експерименти, виконані рентгенодифракційний і енергодисперсійний рентгенівський мікроаналізи плівки, осадженої на підкладку після лазерного впливу на суміш оксидів B₂O₃/ZrO₂.Для изучения физико-химических процессов, происходящих на стадии нагрева магнитоплазменной переработки отработавшего ядерного топлива (ОЯТ), проводится исследование термодесорбции оксидов и оксидных смесей – имитаторов ОЯТ при воздействии стационарного лазерного излучения. Проведены предварительные эксперименты, выполнены рентгенодифракционный и энергодисперсионный рентгеновский микроанализы пленки, осажденной на подложку при лазерном воздействии на смесь оксидов B₂O₃/ZrO₂