The influence of large-scale turbulence on the structure of the density current boundary layer
The influence of large-scale turbulence on the structure of the density current boundary layer
В.I. Samolubov, A.Yu. Pyrkin
The results of complex natural measurements in the upper contact zone of near-floor density flow are used to analyze the repeating cyclic transformations of the structure of the boundary layer of the flow which were observed by registrations lasting several hours. We establish the interdependence of the appearance of fine structure elements of the mixed layer in the stratified flow, such as the lens of translucent liquid, temperature inversions, minima in the velocity profiles, and of the root-mean-square values of its fluctuations. An analysis of the results of discrete and continuous measurements of the profiles of velocity, concentration of suspension and temperature, and aslo the use of spectral analysis, make it possible to interpret the observed phenomena as the effects of generation and dissipation of outer-scale turbulent formations on the vertical structure of the boundary layer. This interpretation is confirmed by quantitative estimates, and agrees well with the main stages of the real process.
Show AbstractCalculation of the frequency spectrum of the electron beam in klystron with premodulation
Calculation of the frequency spectrum of the electron beam in klystron with premodulation
Yu.K. Alexeev, A.I. Kostienko
The example of transit clystron is used to consider a combined perturbation of a one-dimensional electron beam. At the beginning, the current density is amplitude modulated (static control) and, subsequently, the electron velocities are modulated (dynamic control). For large ratios of the control frequencies, a computer was used to calculate the spectral characteristics of the convection current at the entrance to the power takeoff device. The calculations show that it is possible to use a low-frequency amplitude premodulation to increase the electron efficiency of clystron-type pulsed devices which operate in the amplification or frequency multiplication regimes.
Show AbstractThe anomalous passage of X-and gamma-rays beams by the three waves difraction
The anomalous passage of X-and gamma-rays beams by the three waves difraction
A.V. Andreev, V.E. Gorshkov, Yu.A. Ilyinskii
We consider a three-wave dynamical problem of the diffraction of x- and gamma rays in the case of non-coplanar diffraction, when the two reflected waves do not interact directly with each other. We obtain approximate equations which describe the propagation of confined beams during three-wave diffraction in perfect crystals. We estimate the conditions of applicability of plane-wave approximation, and present numerical estimates.
Show AbstractSurface light wave diffraction in planar waveguide on a surface acoustic wave
Surface light wave diffraction in planar waveguide on a surface acoustic wave
V.N. Parygin, N.S. Tankovski
We formulate a general equation for the interaction of light in the planar surface-acoustic-wave lightguide and obtain a solution of this equation which determines the intensity of light in all possible modes and diffraction orders. We show an analogy between the diffraction of light in a multi-mode lightguide and in an anisotropic medium.
Show AbstractPolarization effects in the bremsstrahlung production of massive measons in magnetic field
Polarization effects in the bremsstrahlung production of massive measons in magnetic field
I.M. Ternov, V.N. Rodionov, V.G. Zhulego, A.I. Studenikin
We obtain the probabilities of bremsstrahlung creation of the massive vector Weinberg-Salam meson in a magnetic field. We study the dependence of the total probability on the axial component of the transition current, and on the spin orientation of.the initial electron. It is shown that the sign of the spin correction can change with the relative magnitude of the axial component of the current.
Show AbstractMechanisms of magnetic losses in fine-grain Ni—Zn ferrites
Mechanisms of magnetic losses in fine-grain Ni—Zn ferrites
V.G. Efremov, E.V. Lebedeva, M.A. Kharinskaya
Polycrystalline samples of nickel-zinc ferrites were used to study the dependence of the excitation threshold of spin waves on the grain size. The measurements were carried out on two series of samples. In the first, the zinc concentration was varied to change the anisotropy field, and in the second, the level of internal losses was varied by the introduction of small addition of cobalt ions. It is shown that, as the anisotropy field decreases (the coupling between grains increases) the increase of the threshold field with decreasing grain size becomes weaker. When cobalt ions are introduced, the dependence of the threshold field on the grain size disappears in the region of large grains, and the larger the cobalt-ion concentration the smaller is the grain size starting from which the threshold field ceases to depend on the grain size.
Show AbstractRadiation damping of waves in cold magnetized plasma
Radiation damping of waves in cold magnetized plasma
L.S. Kuz'menkov, P.B. Podosenov, P.A. Polyakov
We study the dispersion and radiation damping of waves in a cold magnetized plasma. We give the appropriate analytical formulae for various frequency cases. It is shown that in a strong magnetic field, the decrement of radiation damping of electromagnetic waves with the righthand circular polarization and the decrement of oscillations near the cyclotron and hybrid frequencies, are proportional to the square of the cyclotron frequency. In a weak magnetic field, the radiation damping decrements of all modes are proportional to the square of the plasma frequency.
Show AbstractOn the theory of spatial resolution enhancement in the SEM functioning in the beta-conductive mode
On the theory of spatial resolution enhancement in the SEM functioning in the beta-conductive mode
G.V. Saparin, V.V. Filimоnоv, A.V. Сhivilev
We consider a problem aimed at increasing the resolution of the scanning electron microscope in the beta-conductivity regime. It is shown that the full analysis of the problem requires investigation of the following aspects of the signal formation in the scanning electron microscope operating in the beta-conductivity regime. Firstly, one needs to calculate the region of scattering of the probe electrons in the volume of the semiconductor in the presence of tangential electric fields. Secondly, one has to study the dynamics of the volume of minority carriers generated by the electron probe as a result of diffusion under the action of electric fields in the object, in the presence of surface recombination. By using a number of assumptions, we analyse the equations for the diffusion of carriers, calculate the concentration for various values of the E field'and surface recombination rate during the pulse of electron current. It is shown that the volume taken up by the electron-hole pairs (the signal volume) depends strongly on the values of the E field and the surface recombination rate. We note that, by using the stroboscopic regime in the scanning electron microscope, one can increase the resolution in the case of beta-conductivity by a factor of 2 - 3.
Show AbstractQuasi-classical spin theory
Quasi-classical spin theory
I.M. Ternov, V.A. Bordovitsyn
The proper-time Dirac equation (τ-equation) is used to develop a quasiclassical theory of spin of the Dirac particles.
Show AbstractBeam solitons in slowing down systems
Beam solitons in slowing down systems
V.K. Grishin, E.N. Shaposhnikova
We consider the possibility of propagation of short beams of charged particles (beam solitons) in a retarding system. By using a selfconsistent analysis of the nonlinear kinetic equation and the Maxwell equations, we obtain the conditions under which the particles which propagate in a dielectric waveguide are confined by the proper longitudinal field. We discuss the possibility of compression of the beam to durations shorter than one nanosecond by using a transformation of the beam parameters.
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