Faculty of Physics
M.V.Lomonosov Moscow State University

## Radiation of a charge in the field of an amplitude-modulated plane wave

### D.L. Chetverikov and G.A. Chizhov

Moscow University Physics Bulletin 1978. 33. N 2. P. 1

Using the methods of classical theory, we examine the motion and radiation of a charge in the field of a circularly polarized amplitude-modulated plane wave. The angular distribution of intensity for radiation by particles is studied both for the case of a harmonically modulated incident wave, and for arbitrary amplitude modulation with polarization effects taken into account. We obtain the total intensity of radiation for the scattering of an amplitude-modulated wave by a charge.

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## Reflection spectra of solid solutions of Pb{0,8}Sn{0,2}Te in the far infrared

### A.G. Belov and E.P. Rashevskaya

Moscow University Physics Bulletin 1978. 33. N 2. P. 7

The reflection spectra of single crystals of Pb{0,8}Sn{0,2}Te and epitaxial films of Pb{0,8}Sn{0,2}Te on a substrate of PbTe were investigated in the wavelength range 20-200 μm at temperatures of 300 and 115°K. The statistics of the free carriers for the Kein zones, the Hall constant, and the plasma frequency are calculated as a function of the position of the Fermi level.

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## Investigation of the fields in an open waveguide with barrel-shaped mirrors

### Yu.A. Pirogov and N.F. Ryapolov

Moscow University Physics Bulletin 1978. 33. N 2. P. 13

The electrodynamics of an open axisymmetrical transmission line consisting of barrel-shaped mirrors is investigated. It is shown that the field distributions and the relations connecting them with the system parameters can be obtained from the scalar wave equation. Single-mode operation is obtained experimentally for different values of the diffraction parameter. The mechanism by which the fundamental mode is established in the line is considered. Good agreement between the experimental and theoretical curves is obtained.

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## Spectral analysis of polyharmonic regime of self-oscillators

### V.V. Karpov

Moscow University Physics Bulletin 1978. 33. N 2. P. 18

A special method is discussed for the analysis of polyharmonic regimes of selfoscillators. An example is presented of the application of this method to an oscillator with a soft limit cycle with a biharmonic force acting on the fundamental mode.

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## Occurrence of maxima of the combination type in mossbauer diffraction

### A.V. Kolpakov, E.N. Ovchinnikova, and R.N. Kuz'min

Moscow University Physics Bulletin 1978. 33. N 2. P. 21

In this paper we discuss the occurrence of maxima of the combination type in the case that the scattering system is located in the fields of interactions with different symmetry. We examine the combination maxima which occur in the diffraction of Mossbauer radiation in the structure RFe_2.

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## Dislocation structure of КСL crystals deformed by ultrasound

### N.A. Tyapunina, E.V. Shtrom, and G.M. Zinenkova

Moscow University Physics Bulletin 1978. 33. N 2. P. 25

The dislocation structure which occurs when ultrasound acts in crystals of KCl was investigated by the composite piezoelectric oscillator method at frequencies of 40-200 kHz with a relative deformation amplitude of ~$10^{-4}$. A difference was found in the development of the plastic deformation process over the frequency range investigated. An increase in the dynamic yield point was observed as the frequency was increased.

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## Polarization and energy flow of transverse waves propagating along the acoustic axes of crystals when external static fields are present

### L.F. Baryshnikova and V.E. Lyamov

Moscow University Physics Bulletin 1978. 33. N 2. P. 31

Using an expansion of the thermodynamic potential and the quasi-static approximation conditions, a system of equations is obtained determining the velocity of elastic waves in piezoelectric crystals acted upon by static fields. For certain classes of crystals, a nonlinear parameter is calculated which represents the elliptic polarization of the transverse waves propagating along the acoustic axes when a constant mechanical stress or an electric field acts on the crystal. An expression is obtained for the energy flow of acoustic waves in crystals in external fields.

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## Exchange matrix element in the theory of atomic collisions

### G.Ya. Korenman and S.I. Rogovaya

Moscow University Physics Bulletin 1978. 33. N 2. P. 38

We develop a method of evaluating Born matrix elements of the exchange type from the Coulomb interaction operator with hydrogenous wave functions.

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## Features of internal modulation of the C0_2-laser

### M.I. Zusman, V.N. Parygin, and A.G. Kukushkin

Moscow University Physics Bulletin 1978. 33. N 2. P. 41

We conduct theoretical and experimental research on the internal modulation of the CO_2 laser. The frequency dependence of the amplitude of the varying component of the radiation intensity is shown to have a resonant character. The resonance frequency, the amplitude of the varying component of the intensity, and the width of the resonance curve are determined. Use of the resonant dependence permits attaining a gain in the amplitude of the modulating voltage 60-70 times greater than for external modulation.

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## Three-frequency parametric system as a twopole with negative parameters

### V.N. Damgov and M.D. Karasev

Moscow University Physics Bulletin 1978. 33. N 2. P. 48

A three-frequency reactive-active parametric modulator is considered, both theoretically and experimentally, which enables one to obtain a wide-band negative conductance and capacitance, inserted into the input circuit.

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## Self-focussing of beams of elliptic cross section

### K.D. Egorov and V.P. Kandidov

Moscow University Physics Bulletin 1978. 33. N 2. P. 56

The stationary self-focussing of beams of elliptic cross section in modes which are close to critical is investigated numerically. The propagation process has an oscillating form. In supercritical modes the beam breaks up into filaments. A computational algorithm is described and its accuracy is investigated.

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## The use of the method of impedance characteristics to analyze the propagation of waves in multilayer structures with absorption

### A.V. Kozar, V.S. Kolesnikov, and Yu.A. Pirogov

Moscow University Physics Bulletin 1978. 33. N 2. P. 61

A multilayer interference absorber (a system which completely absorbs incident energy in a thin layer of weakly absorbing material—the working layer) is analyzed using the method of impedance characteristics. The condition for resonance(practically complete) absorption is obtained as a function of the parameter of the working layer and the parameters of the multilayer structure for different modifications of the absorber, and the width of the absorption band is determined. The effect of small losses in the layers on the fundamental characteristics of the absorber is considered.

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## Effect of a thermal lens in a crystal of yttrium aluminum garnet on the stability of the emission of a continuous laser

### Yu.D. Golyaev, A.V. Grushetskii, K.N. Evtyukhov, and L.N. Kaptsov

Moscow University Physics Bulletin 1978. 33. N 2. P. 68

It is shown that the relative fluctuations in the focal length of the thermal lens induced in the YAG:$Nd^{3+}$ crystal of a continuous laser with a common cooling flow of the pumping lamp and the crystal, have a value of the order of 20%. A theoretical calculation, confirmed by experimental measurements, shows that these fluctuations are due to relative variations in the emission power of not less than 10%, and also have a considerable effect on the spectral composition of the emission.

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## The effect of the destabilizing factors on the frequency and line width of a three-circuit oscillator

### I.I. Minakova, V.I. Panov, and S.Yu. Pashin

Moscow University Physics Bulletin 1978. N 2.

In this paper'is considered the effect of fluctuations and of destabilizing factors on the long term frequency stability and on the oscillator line width of three-cavity microwave oscillators with a stabilizing superconducting resonator. For a real oscillator with a tunnel diode the conditions are analyzed for the achievement of relative frequency fluctuations $≤10^{-15}$

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## Periodic motions of an axisymmetric satellite relative to the center of mass in an evolutionary circular orbit (II)

### Yu.V. Barkin

Moscow University Physics Bulletin 1978. 33. N 2. P. 78

The existence of periodic solutions in the problem of the motion of an axisymmetrical satellite relative to the center of mass in an evolutionary circular orbit is investigated. The motion of the satellite is described by canonical osculating Andoyer elements, referred to the mobile plane of the orbit. The analytical conditions for the existence of Poincare periodic solutions are obtained, the generating solutions of which are interpreted as generalized Cassini laws for bodies possessing an axis of dynamic symmetry. A qualitative and numerical investigation of the generating solutions is presented.

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## The effect of viscosity on the resonance properties of expansion chambers

### A.V. Egor'ichev, P.N. Kravchun, and К.V. Chernyshev

Moscow University Physics Bulletin 1978. 33. N 2. P. 86

The effect of the viscosity of the medium on the resonant properties of an expansion chamber is considered using the model of a linear viscous liquid. It is shown that when the existence of viscous waves in the medium is neglected, the acoustic field in the chamber is completely determined by the velocity scalar potential. The results of a computer calculation of the damping level of a chamber with a viscous medium are presented for two different chamber sizes and three values of the effective kinematic viscosity.

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## Theory of the temperature superlattice in semiconductors with hot electrons

### V.L. Bonch-Bruevich

Moscow University Physics Bulletin 1978. 33. N 2. P. 89

We study the conditions for the occurrence of a temperature superlattice (the "Benar problem") in superconductors with bipolar conductivity. It is assumed that the charge carriers are created mainly by the (rather intense) heating light itself.

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## Amplification properties of a synchronized self-oscillator

### V.V. Karpov and M.E. Kvasov

Moscow University Physics Bulletin 1978. 33. N 2. P. 95

## Conversion of a radio signal in a paramagnetic circuit with pulsed pumping

### V.P. Komolov and V.A. Roznyatovskii

Moscow University Physics Bulletin 1978. 33. N 2. P. 98

## Investigation of the decomposition of a supersaturated solid solution of Ti-Nb-Al alloy

### M.I. Zakharova, N.A. Khatanova, and N.A. Kozlovskaya

Moscow University Physics Bulletin 1978. 33. N 2. P. 101

## Asymptotically free models and the $G_2$-group

### Yu.N. Kolmakov, N.F. Nelipa, and M. Chaichian

Moscow University Physics Bulletin 1978. 33. N 2. P. 105

## Analysis of the variation of the parameters of superconducting resonators in a magnetic field

### P.I. Zubietov

Moscow University Physics Bulletin 1978. 33. N 2. P. 107