Covariant formulation of the dynamic theory of mossbauer diffraction
Covariant formulation of the dynamic theory of mossbauer diffraction
M.A. Andreeva, S.F. Borisova
Methods of direct tensor computation are introduced for the solution of the system of vector equations of the dynamic theory of diffraction for the first time. A covariant representation of the dynamic coefficients is given for the dynamic coefficients for various multipolar Mossbauer transitions in the presence of hyperfine splitting. In the two-wave case, a general solution is given for the scalar interaction and also for an individual Zeeman component of the Mossbauer spectrum. It is shown that, in the latter case, a suppression effect is possible for radiation of any multipolarity. The need to take account of refraction effects is noted in calculating the dynamic coefficients in the limiting asymmetric case of diffraction in the presence of an interaction of tensor type.
Show AbstractTheory of parametric receiving antenna
Theory of parametric receiving antenna
E.A. Devyaterikova, L.K. Zarembo
A theory of а рarametric receiving antenna is presented first for a quasiplane axisymmetric beam of the reference wave in a medium with losses and then with diffraction of this beam taken into account. The directional chacteristics are obtained, and an analysis of the axial distribution of the parametric signal is performed. Losses lead to "smoothing" of the load structure. Taking account of the characteristic isotropic background noise, the optimal size for the base of the receiving antenna is found; it is larger than the distance at which the amplitude of the parametric signal is a maximum.
Show AbstractElectron diffraction at thin plates of ε- martensite
Electron diffraction at thin plates of ε- martensite
H.A. Matutes (Cuba), N.A. Khatanova
By the methoi of electron microscopy and electron diffraction, the structure of the alloy Fe - 20 at. % Ru after quenching from 900°C is determined. It is shown that the alloy consists of alternating thin layers of the matrix and e martensite. Such a morphology of a twophase alloy leads to the expansion of points of the inverse lattice and, consequently, to the appearance of extra reflexes and also reflexes from double diffraction, resembling diffraction from a modulated structure, on the electron-microscope traces.
Show AbstractSteady calculation in a shallow sea
Steady calculation in a shallow sea
N.K. Shelkovnikov, S.M. Novochinskii, I.S. Rakitina
Results are given of an experimental investigation of the structure of the flow arising with wind impulsion in a homogeneous liquid above a slope, in conditions modeling the coastal shelf of a sea.
Show AbstractIr induced three-photon light scattering in rubidium vapor
Ir induced three-photon light scattering in rubidium vapor
N.V. Znamentskii, V.I. Odintsov
In conditions of frequency tuning of the exciting radiation, the energy threshold, and spectral characteristics of the infrared induced three-photon scattering (IR ITPS) of light in rubidium vapor are investigated. It is established that induced cascade transition arising as a result of multiphoton ionization of the atoms has a significant influence on the occurrence of this process. The features of IR ITPS excitation are investigated for the case where the conditions of both two-photonn (5${^2}$S$_{1/2}$—5$^{2}$D$_{5/2}$) and single-photon(5${^2}$S$_{1/2}$ — 5$^{2}$ P$_{3/2}$)resonance are simultaneously satisfied. It is observed that, on approaching the single-photon resonance,the reduction in excitation threshold and icrease in energy of the scattered radiation that is expected from theory is not observed, but instead the completely opposite picture; the excitation threshold rises and the energy decreases.This contradiction between theory and experiment is explained.
Show AbstractComponents of the heat flux from the sea into the atmosphere
Components of the heat flux from the sea into the atmosphere
E.G. Andreev, A.Yu. Pyrkin
Results are presented of natural investigations of the total heat flux and effective long-range radiation of the surface of the sea during expeditions in 1977-1979 to the open sea. Prom the data of recordings made over many days and synchronously, curves of the daily trend of the heat-flux components from the sea into the atmosphere are plotted.
Show AbstractFourth moments of fluctuations in some nonlinear distributed radiophysical systems
Fourth moments of fluctuations in some nonlinear distributed radiophysical systems
A.V. Tolstopyatenko
For a two-conductor line, the four-point correlator of the potential and current is calculated. Two cases are considered: nonlinear conduction of the directing conductors; and a "linear" line loaded by a nonlinear resistance. The correlator is calculated using cubic relations of nonlinear fluctuational-dissipative thermodynamics. The indeterminacy remaining after the phenomenological equations are specified reduces to the presence of a single numerical parameter that is dissipationallу undetermined.
Show AbstractRepresenting the lofgitudinal dielectric permittivity of relativistiс plasma by a convenience series in the long-wave region
Representing the lofgitudinal dielectric permittivity of relativistiс plasma by a convenience series in the long-wave region
L.S. Kuz'menkov, P.A. Polyakov, M.I. Sitnov, О.O. Trubachev
For the longitudinal dielectric permittivity of relativistic plasma in the long-wave region, a representation in the form of a uniformly converging series is obtained; this representation is valid over a broad range of temperatures and wave vectors. If the temperature is not too small in the long-wave region, this series converges rapidly, ensuring high accuracy of the representation when only the first few terms of the series are used.
Show AbstractOptimal linear electrooptical effect in crystals of мм 2 and мм 4 classes
Optimal linear electrooptical effect in crystals of мм 2 and мм 4 classes
V.A. Dianova, E.R. Mustel
The optimal directions of linear longitudinal and transverse electrooptical effects are determined for crystals of classes mm2 and 4mm. The minimal halfwave potentials are given for NaBa$_2$ Nb$_5$O$_15$ and Ba$_0,25$ Sr$_0,75$ NB$_2$ O$_6$.
Show AbstractDynamic characteristics of adaptive mirror
Dynamic characteristics of adaptive mirror
D.V. Pruidze, Yu.S. Rendel
Adaptive optical systems are used to ensure maximum angular resolution of telescopes in observing remote objects through a turbulent atmosphere, and also for focusing radiation onto remote objects in a nonlinear and turbulent medium. The potential of additive systems is largely determined by the type of corrector used and its parameters: the band of working frequencies and the sensitivity. The parameters of correcting mirrors are expediently measured by interferometric methods.
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