Small-Scale Analysis of Hydrodynamical Helicity Suppression in the Mean-Field Dynamo-Model

Journal of Experimental and Theoretical Physics - We compare the classical mean-field dynamo model proposed by Steenbeck, Krause, and Rädler to describe the generation of large-scale magnetic...     

Determining the statistical weight of multicluster wave functions for light nuclei in a parametrized phase analysis

The experimental angular distributions of light alpha-cluster nuclei are described. Based on fitting, we find that the experimental angular distribution splits into two diffraction modes: the first has a short oscillation period on the nucleus as a whole, and the second has long oscillation periods on the alpha-cluster substructures. Fitting also reveals that the cross sections rising above the Rutherford level for light nuclei is explained by the additivity (modulation) of the alpha-particle mode of elastic scattering (the scattering of alpha particles on alpha-particle clusters).     

Global unsolvability of a nonlinear conductor model in the quasistationary approximation

We study initial-boundary value problems for a model differential equation in a bounded region with a quadratic nonlinearity of a special type typical for the theory of conductors. Using the test function method, we show that such a nonlinearity can lead to global unsolvability with respect to time, which from the physical standpoint means an electrical breakdown of the conductor in a finite time. For the simplest test functions, we obtain sufficient conditions for the unsolvability of the model problems and estimates of the blowup rate and time. With concrete examples, we demonstrate the possibility of using the method for one-, two- and three-dimensional problems with classical and nonclassical boundary conditions. We separately consider the Neumann and Navier problems in bounded R ^N regions (N ≥ 2).     

Estimating the limits of the Fresnel diffraction range for de broglie waves corresponding to particles with Z = 1–2 incident on various nuclei

The aim of this work is to determine the regions where Fresnel diffraction can be observed on different nuclear targets at different energies of the incident particles. The boundaries of the corresponding regions are determined, allowing us to estimate the range of the nuclear targets and the energies of the incident particles upon whose interaction we observe the diffraction effect.     

Acoustic scattering by turbulent fluctuations of pressure and entropy

Detailed analysis is presented of the well-known Tatarskii’s formula, which describes sound wave scattering in a turbulent atmosphere. The adiabaticity of the acoustic fluctuations and incompressibility of the turbulent fluctuations are assumed only. This yields to additional 1 terms in the classical formula (probably, small in the inertial range of turbulence). We show the change of Obukhov’s formula, which describes the connection between turbulent fluctuations of pressure and velocities in a compressible atmosphere, and also demonstrate the effect of the independence of fluctuations of the potential and thermodynamic temperatures. By analogy with the formula for small-scale isotropic temperature fluctuations, which was also obtained by Obukhov, we derive a formula for the fluctuations of entropy and potential density as function of entropy, which describes spatial distribution of the probability density of identical “fluid particles” in the turbulent media.     

Investigation of the Directional Velocities of Ions in a Vacuum Arc Discharge by Emission Methods

This paper is devoted to an investigation of the directional velocities of the ions generated in cathode spots of vacuum arc discharges. By using emission methods of studying the processes in a vacuum arc discharge, which involve the determination of the parameters and characteristics of the discharge plasma by analyzing the ion current extracted from the plasma and the ion charge states, the velocities of ions have been determined for the majority of cathode materials available in the periodic table. Is has been shown that at a low pressure of the residual gas in the discharge gap the directional velocities of the ions do not depend on the ion charge state. Comparison of the data obtained with calculated values allows the conclusion that the acceleration of ions in a vacuum arc occurs by the magnetohydrodynamic mechanism.     

Measurements of neutron fluxes with energies from thermal to several MeV in near-Earth space: SINP results

Neutron measurement results obtained at SINP MSU since 1970 are presented. These measurements were made using techniques based on neutron moderation and subsequent detection in a Li6I(Eu) crystal or a He3 coronal counter. The measurements were mainly carried out in orbits with inclination of 52 degrees and altitudes of 200-450 km. The spatial and angular distributions of the measured neutron fluxes were studied. The albedo neutron flux was estimated according to the count rate difference for opposite detector orientations towards Earth and away from it. This flux is comparable to the local neutron flux outside the Brazil anomaly region, where local neutrons dominate. Neutron fluxes, generated by solar protons, were detected during a solar flare on June 6, 1991 for the first time. Their spectrum was estimated as a power law with alpha>2.     

Sea-level muon spectrum in the energy range 1–10 TeV from the data of underground experiments

Within an adjoint approach, the properties of the muon component in various types of rock and in water are calculated with allowance for fluctuations of energy losses in all muon-interaction processes. The behavior of the muon spectrum at sea level is established on the basis of a comparison of the muonabsorption curves obtained in this way and experimental data from underground facilities. It is shown that the deficit of the calculated muon flux obtained with the aid of data from direct measurements of the spectra of primary nuclei and Reggeon models of nuclear interactions is not less than 50% in the energy range 1–10 TeV.