—The effect of charge-carrier drift on the plasmon excitation modes (plasmons) in a Dirac electron liquid in graphene with a displaced Fermi level is considered. The dispersion relations for plasmons ...are obtained using the electromagnetic approach and hydrodynamic description of the electron liquid. Damped and amplified plasmon eigenmodes are studied numerically depending on the relationship of the magnitudes and directions of the direct electrical current and the plasmon phase velocity.
The possibility of determining the difference in gravitational potentials and orthometric heights in the Earth’s field based on measurements of the phase difference of laser radiation in an optical ...fiber is proposed and investigated in this study. Such a phase difference is attributed to the effect of the gravitational delay of light waves. A block diagram of a measuring complex designed to measure the phase difference of light waves caused by this effect is proposed. The measurements use two coherent light waves from a single laser, each propagating along a separate fiber-optic communication line. The composition of each fiber-optic communication line includes the same coils of a long optical fiber, spaced apart in height. The analysis of the factors influencing the phase relations of waves propagating along two communication lines of the measuring complex is performed. The phase effects of the delay, caused by the influence of the true gravitational field of the Earth, and the influence of the fields of inertial forces and gyroscopic effects due to the Earth’s rotation are determined. Methods for suppressing interfering effects are proposed. The achievable errors in measuring the differences in gravitational potentials and corresponding orthometric heights are estimated. With a fiber length in coils of 100 km and a height difference of 100 m, the errors are 0.2 m
2
/s
2
and 2 cm, respectively. The measuring complex under study is called a laser gravipotentiometer. It is an optical analog of the well-known radio-frequency quantum-level unit, but it does not require ultrastable frequency and time standards. The research results of the proposed measuring complex are relevant for the development and improvement of measuring instruments for the parameters of the Earth’s gravitational field and a means of the high-precision synchronization of time scales of remote standards.
The spectrum of amplification of terahertz radiation in a structured active graphene bilayer consisting of two identical periodic graphene microribbon arrays separated by a thin dielectric barrier ...layer is theoretically investigated. The system supports optical and acoustic plasmon modes. The resonant frequencies of the optical and acoustic modes change oppositely with the dielectric-layer thickness, which allows plasmon-mode anticrossing. It is shown that the investigated graphene structure is characterized by a strong plasmon response and giant terahertz-radiation amplification at plasma resonance frequencies in the vicinity of the anticrossing between the optical and acoustic plasmon modes at room temperature.
Abstract
While designing phase-correlation direction finders, as antenna components, the non-directional ones are usually applied. Mounting the non-directional antenna components provides certain new ...options but makes the bearing computation procedure more problematic. In the present paper, the feasibility of using the directional antenna components is discussed and confirmed in terms of its positive influence on the stability of the bearing results in the case when the deviations of the implementations of the actual diagrams of the antenna components from their reference model occur.
Abstract
Weak plasmon modes in periodic structures with a two-dimensional electron gas without an inversion center are studied theoretically. The asymmetry of the electric field and Fourier harmonics ...of weak plasmon modes can lead to the excitation of a travelling plasmon by an electromagnetic wave normally incident on the structure and to the appearance of nonlinear effects leading to the rectification of the incident radiation. The low radiation damping of weak plasmon modes can be used to increase the efficiency of terahertz plasmon amplifiers.
The absorption/amplification spectrum of terahertz radiation in inhomogeneous graphene (
n–i–p–i
structure) with a periodic dual metal grating is theoretically investigated. It is shown that the ...amplification of terahertz radiation sharply increases at the plasmon-resonance frequency, when losses due to electron scattering and emission are balanced by the plasmon gain (related to the stimulated radiative interband recombination of electron–hole pairs in the inverted region of graphene).
The dependence of the plasmon terahertz resonant frequency in the generation mode on the quasi-Fermi energy in the active (ungated) region of graphene with an inverse charge carrier population and on ...the Fermi energy in the gated
p
- and
n
-type regions in a periodic
p
–
i
–
n
structure based on graphene with injection pumping is theoretically investigated. It is shown that electrically frequency-tunable nanoscale plasmon graphene amplifiers and generators operating in a broad terahertz frequency range at room temperature can be designed.
In situ formation of 2-methylimidazole as a result of 2,4,6-trimethyl-1,3,5-hexahydrotriazine trihydrate and glyoxal interaction in an aqueous solution is studied for the first time using NMR ...spectroscopy. In addition to the reactants and products, the reaction mixture is shown to contain stable intermediate products of the trimer decomposition as well as glycolic acid.
—
A kicker magnet has been developed for the NICA accelerator complex at the JINR (Dubna) for ejecting ions into the beamline that connects the Booster and Nuclotron synchrotrons. An asymmetric ...design of the magnet without a ferromagnetic core is used to obtain the required magnetic field of 0.17–0.18 T in the region of the extracted beam. A power-supply system is proposed for the kicker magnet; it is based on two generators with different polarities, which are connected from opposite ends. This kicker magnet has made it possible to successfully extract He and Fe ions from the NICA Booster in accordance with the specified parameters.
A man-induced seismic activation occurring near the Bachat open-cast coal mine in Kuzbass is studied. The Bachat earthquake of June 18, 2013 (
M
L
= 6.1) is the world’s largest man-made earthquake ...related to the extraction of solid minerals. It created a powerful aftershock process. More than 3000 earthquakes have been recorded. It was found that the seismic process in the area of the mine as of 2020 is continuous and non-stationary: there are periods of background seismicity with relatively small and infrequent events, and periods of activations with earthquakes that are felt throughout the entire Kemerovo region (
M
L
≥ 4), and an increased (by 2‒3 times) frequency of small events. The duration of seismic activations is 1‒3 months. Focal mechanisms of 76 events were determined for the mine area. The fact of mismatch between the model of the stress state of the Bachatsky open-cast coal mine area as recovered from the mechanisms of aftershocks and the mechanism of the main shock of the Bachat earthquake is found.
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