共查询到20条相似文献,搜索用时 31 毫秒
1.
S. V. Latyshev 《Technical Physics》1997,42(7):828-831
The potential possibilities of a plasma heated by laser radiation as a negative-ion source are analyzed theoretically. It
is shown that the efficiency of negative-ion formation in a laser plasma in the heating phase reaches 1015−1016 ions/J when the parameters of the laser radiation are optimally adjusted.
Zh. Tekh. Fiz. 67, 117–120 (July 1997) 相似文献
2.
A passive tracer on the surface of an incompressible liquid behaves like a tracer in two-dimensional compressible flows, whose
characteristic feature is the formation of cluster structures, i.e., compact regions of increased density surrounded by vast
low-density regions. The cluster formation dynamics are studied, and statistical spatiotemporal characteristics of the density
fields, which faithfully reflect the properties of the cluster structures, are calculated.
Zh. éksp. Teor. Fiz. 111, 1297–1313 (April 1997) 相似文献
3.
V. V. Vecheslavov 《JETP Letters》1996,63(12):1047-1053
A new effect [V. V. Vecheslavov, Zh. éksp. Teor. Fiz. 109, 2208 (1996) (JETP 82, 1190 (1996)]—the appearance of low-frequency secondary harmonics in the separatrix mapping of a system—is discussed in detail
for the example of a pendulum with a two-frequency perturbation. It is shown that there exist regions of values of the perturbation
parameters where these harmonics make the main contribution to the formation of the chaotic layer of the fundamental resonance.
The results of analytical and numerical determinations of the amplitudes of the secondary harmonics are compared.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 12, 989–994 (25 June 1996) 相似文献
4.
A. A. Skovoroda 《Journal of Experimental and Theoretical Physics》1997,85(3):474-483
Experiments and a theoretical model consistent with them are presented which show that a stationary microwave discharge in
a gas at atmospheric pressure under the action of free convection due to the action of the buoyant force on the heated air
can be spatially localized, taking a spheroidal shape. Vortex motion inside the spheroid gives this localized plasma formation
some of the properties of a material body which are manifested in a distinct material isolation from the surrounding space,
in the formation of a narrow thermal boundary layer and flow separation, and in the formation of secondary vortices in the
wake region. The characteristic radius of the stationary localized plasma is governed mainly by the wavelength of the microwave
radiation a∼0.137λ. Energy balance is established to a significant degree by convective cooling of the microwave-heated structure.
Zh. éksp. Teor. Fiz. 112, 877–893 (September 1997) 相似文献
5.
V. E. Fortov A. P. Nefedov V. M. Torchinskii V. I. Molotkov A. G. Khrapak O. F. Petrov K. F. Volykhin 《JETP Letters》1996,64(2):92-98
The formation of macroscopic ordered structures in the standing striations of a stationary glow discharge in Ne is observed.
A Coulomb quasicrystal is formed by spherical glass particles with diameters of 50–63 μm and charge Z
p~7·105
e. The interparticle distance is approximately 300 μm. This corresponds to a nonideality parameter Γ~5·104, which leads to crystallization in the Yukawa model. The factors leading to the formation of a quasicrystal in the striations
are discussed.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 2, 86–91 (25 July 1996) 相似文献
6.
A. P. Nefedov O. F. Petrov Ya. K. Khodataev S. A. Khrapak 《Journal of Experimental and Theoretical Physics》1999,88(3):460-464
The molecular dynamics method is used to model the formation of ordered structures of charged macroparticles in a thermal
plasma at atmospheric pressure. The results of the numerical calculations are compared with the experimental data. It is shown
that the ordered structure of macroparticles detected experimentally is far from steady state, since the existence time of
the plasma in the experiment is less than the characteristic time of formation of the structure.
Zh. éksp. Teor. Fiz. 115, 837–845 (March 1999) 相似文献
7.
L. L. Savchenko S. A. Nikitov A. F. Popov M. V. Chetkin 《Journal of Experimental and Theoretical Physics》1998,87(2):342-348
A theoretical analysis is made of the formation and evolution of modulational instability of a traveling magnetostatic spin
wave in a ferromagnetic film. Results of earlier experiments are analyzed and it is demonstrated that the experimental results
can be explained using a model describing the evolution of the signal wave and initial noise allowing for their nonlinear
interaction. The instability process is simulated numerically and the results are compared with calculations using a deterministic
model. Mechanisms are discussed for the loss of spectral symmetry in the formation of modulation frequency satellites.
Zh. éksp. Teor. Fiz. 114, 628–639 (August 1998) 相似文献
8.
Experimental data on the electrical and optical properties of a thin layer of a magnetodielectric colloid obtained by Kozhevnikov
et al. (Tech. Phys. 51 (7), 946 (2006)), are analyzed. Using a three-layer hierarchical model, the possible structure and properties of near-electrode
layers are determined, the formation mechanisms of dynamic structures are described, and the variation of the electrical properties
of the magnetodielectric colloid layer with time and constant electric field strength are discussed. 相似文献
9.
An analysis is made of the transformation of a plane monochromatic electromagnetic wave in response to a temporal change in
the permittivity and conductivity of a semibounded medium. The change in the parameters of the medium takes the form of a
rectangular pulse of arbitrary duration and amplitude. The detailed structure of the electric field and its evolutional redistribution
are determined. The asymptotic formation of a backward wave is demonstrated, whose amplitude may exceed that of the primary
wave for parameters typical of a semiconductor.
Zh. Tekh. Fiz. 69, 84–92 (August 1999) 相似文献
10.
In this paper the aggregates of the chiral organolithium N-Boc-2-lithiopiperidine [Boc=CO2C(CH3)3], which play an important role in the formation of chiral 2-substituted piperidines found in many alkaloid structures and medicinal compounds, have been investigated within the framework of Density Functional Theory (DFT) calculations. In the complex structures, the lithium atoms are tetra-coordinated, the diaminoalkoxide ligand is tridentate to one lithium atom and forms a chelate with the substrate which is stabilized by the solvent diethyl ether. The same type of bonding was observed for all the different ligand-bound structures; for ligands 6 and 7, which have bulky substituents, selectivity was in agreement with experiment. The results shed light on the microscopic structures of these species and suggest a potential ligand, 11, to yield high enantioselectivity. 相似文献
11.
I.A. Nyrkova A.N. Semenov A. Aggeli N. Boden 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(3):481-497
The problem of fibril (fibre) formation in chiral systems is explored theoretically being supported by experiments on synthetic
de novo 11-mer peptide forming self-assembled -sheet tapes. Experimental data unambiguously indicate that the tapes form fibrils of nearly monodisperse thickness ca
. 8-10 nm. Fibril formation and stabilisation are attributed to inter-tape face-to-face attraction and their intrinsic twist,
correspondingly. The proposed theory is capable of predicting the fibril aggregation number and its equilibrium twist in terms
of molecular parameters of the primary tapes. The suggested novel mechanism of twist stabilisation of finite aggregates (fibrils)
is different to the well-known stabilisation of micelles in amphiphilic systems, and it is likely to explain the formation
and stability of fibrils in a wide variety of systems including proteinaceous amyloid fibres, sickle-cell hemoglobin fibres
responsible for HbS anemia, corkscrew threads found in chromonics in the presence of chiral additives and native cellulose
microfibrillar crystallites. The theory also makes it possible to extract the basic molecular parameters of primary tapes
(inter-tape attraction energy, helical twist step, elastic moduli) from the experimental data.
Received 7 May 1999 and Received in final form 15 February 2000 相似文献
12.
Abstract When high-energy electrons penetrate crystalline matter, the successive processes of photon emission and pair production form an electromagnetic shower. If the incident electrons are directed along the crystal axis, the cross section for photon emission is drastically enhanced because electrons in ‘channeling’ states feel a strong electric field continuously. Experiments designed to detect this effect were performed at CERN. The results showed an anomalous peak in the energy loss spectrum of the emerging electrons. In this paper, we report results of a Monte-Carlo simulation of shower formation in a Germanium crystal. Our results agree with the experimental data more quantitatively than previous simulations. We simulated a shower formation by incident photons as well. 相似文献
13.
The current-voltage characteristics (IVCs) of Cu−K0.3MoO3 point contacts are investigated. The character of the nonlinearity and the observed asymmetric features of the IVCs indicate
that a substantial shift of the chemical potential occurs near the boundary with the normal metal. Deformation of the charge
density wave by an applied electric field leads to strong bending of the energy bands and to the formation of a potential
well, whereupon the Fermi level falls within the region of allowed single-electron states.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 2, 146–151 (25 January 1998) 相似文献
14.
A model of a ferromagnet with nonuniform dissipation is introduced for the Landau-Lifshitz equations. It is shown that in
this model a ferromagnet can be regarded as an oscillating active medium where the formation of autowave structures — spin
autowaves, pacemakers, and spiral waves — is possible. Their wave characteristics, expressed in terms of the parameters of
the medium, are found for a special case.
Fiz. Tverd. Tela (St. Petersburg) 39, 513–515 (March 1997) 相似文献
15.
New differential equations describing the dynamics of the formation of temperature and moisture fields in capillary-porous
media are derived on the basis of a complete analysis of the physical processes occurring in a capillary-porous body. The
derivation of the equations is based on the well-known diffusion laws and functional relations between the temperature, moisture
content, and vapor content, which are physical characteristics of the body. The equations obtained contain experimentally
measurable physical quantities and dependences which characterize a specific capillary-porous body.
Zh. Tekh. Fiz. 68, 140–142 (February 1998) 相似文献
16.
A. L. Semenov 《Physics of the Solid State》1997,39(5):826-829
A two-parameter, Peierls-type model of the metal-semiconductor phase transition is proposed. The order parameters, which represent
the normalized amplitudes of static strain modes of the crystal, are coupled through the anharmonicity of interatomic interaction.
The model is used as the basis of a theory accounting for the structural changes and formation of the band gap in the electron
spectrum during phase transition in vanadium dioxide.
Fiz. Tverd. Tela (St. Petersburg) 39, 925–928 (May 1997) 相似文献
17.
V. P. Starodub 《Technical Physics》1998,43(6):735-736
The mechanisms for formation of population inversions in plasma jets of lithium, sodium, cadmium, and strontium vapor are
studied. The primary contribution to forming a population inversion over the transitions of the alkali atoms is found to be
three-body electron-ion recombination, and for transitions between the ion levels of strontium and cadmium, inelastic collisions
with the buffer gas play an important role. Using helium instead of argon as a buffer leads to a substantial increase in the
magnitude of the inversion.
Zh. Tekh. Fiz. 68, 134–135 (June 1998) 相似文献
18.
A. L. Semenov 《Journal of Experimental and Theoretical Physics》1999,88(4):716-725
This paper is a theoretical study of the properties of the low-temperature phase of a Peierls system when nonequilibrium electron-hole
pairs are excited in the phase. A microscopic theory is developed to show that at low temperatures a spatially nonuniform
periodic structure with a modulated band gap forms in the thermodynamically nonequilibrium system considered. The critical
temperature of formation of such a superstructure, the critical electron-hole pair concentration, the spatial period, and
the percentage modulation are calculated.
Zh. éksp. Teor. Fiz. 115, 1297–1314 (April 1999) 相似文献
19.
M. I. Barnik A. S. Zolot’ko V. F. Kitaeva 《Journal of Experimental and Theoretical Physics》1997,84(6):1122-1130
The interaction of linearly and circularly polarized beams with a nematic liquid crystal doped with light-absorbing dyes has
been studied by light-diffraction and microprojection methods. It has been found that there is a threshold for the emergence
of light-induced anisotropic structures, which, depending on the type of dye, can be axisymmetric or extended in a direction
determined by the light field. Possible mechanisms leading to the formation of the anisotropic structures are discussed.
Zh. éksp. Teor. Fiz. 111, 2059–2073 (June 1997) 相似文献
20.
Experimental data are used as a basis for discussion of the principal methods of cluster formation in the laser ablation of
targets: condensation during expansion of the cloud of evaporated material, clustering at the surface accompanying redeposition
of material back on the target, and emission of entire nanoblocks from the target. Methods of distinguishing between these
processes are discussed.
Zh. Tekh. Fiz. 69, 81–84 (September 1999) 相似文献