共查询到20条相似文献,搜索用时 62 毫秒
1.
K. Dyabilin R. Klíma I. Ďuran J. Horáček M. Hron P. Pavlo J. Stöckel F. Žáček 《Czechoslovak Journal of Physics》2001,51(10):1107-1117
Electrostatic drift turbulence of the edge plasma in the CASTOR tokamak is studied numerically by using the Hasegawa-Wakatani equations. The fluctuations of plasma density and potential as well as the corresponding fluctuation-induced particle flux are calculated for regimes with various plasma poloidal flows. Results of numerical simulations are in a reasonable agreement with experimental results. 相似文献
2.
Sergiy Kotrechko Oleksandr Ovsjannikov Tatjana Mazilova Igor Mikhailovskij Evgenij Sadanov 《哲学杂志》2013,93(12):930-943
AbstractExperimental value of strength of nano-sized crystal under uniform triaxial (hydrostatic) tension was obtained for the first time. Strength was measured by in situ high-field mechanical testing of tungsten defect-free nano-sized specimen carried out inside a field-ion microscope. At temperature 77 K, this strength is 28 ± 3 GPa. Based on the MD simulation findings, it is ascertained that under these conditions the instability of an entire nano-sized specimen (global instability) is initiated by the Bain transition within a local region of the specimen. The model of ‘fluctuation-induced Bain transition’ is offered. Within the framework of the model proposed, it is exhibited that possibility of realisation of such local Bain transition under global hydrostatic tension is due to the fluctuation of local tensile stresses. In general, it is shown that fluctuation-induced Bain transition governs the level of the strength of nano-sized bcc crystals under hydrostatic tension. 相似文献
3.
The fluctuation-induced dynamo has been investigated by direct measurement of v and b in the edge of a reversed-field pinch and is found to be significant in balancing Ohm's law. The velocity fluctuations producing the dynamo emf have poloidal mode number m = 0, consistent with MHD calculations and in contrast with the core m = 1 dynamo. The velocity fluctuations exhibit the parity relative to their resonant surface predicted by linear MHD theory. 相似文献
4.
The time-of-flight characteristics of a spherical-mirror electrostatic energy analyzer of charged particle fluxes are investigated
under conditions of ideal solid-angle focusing for a point source located on the symmetry axis of the spectrometer. It is
shown that the time it takes a particle to move from the source to the ideal focus, also located on the symmetry axis, is,
to first order, independent of particle direction for directions near the normal to the axis. This time-of-flight focusing
realized in this way enables efficient use of the spherical-mirror analyzer in electron spectroscopy methods in which each
emission event is registered separately.
Zh. Tekh. Fiz. 69, 109–113 (January 1999) 相似文献
5.
G. M. Batanov L. V. Kolik A. E. Petrov K. A. Sarksyan N. N. Skvortsova O. I. Fedyanin N. K. Kharchev Yu. V. Khol’nov S. V. Shchepetov C. Hidalgo B. van Milligen 《JETP Letters》1998,68(7):585-591
The results of an experiment show that in the edge plasma of a L-2M stellarator the radial electric field is one of the determining
factors influencing the formation of spatial structures and fluctuational particle fluxes. A point where the poloidal velocity
of the fluctuations reverses is observed in an experiment with a high neutral-gas flux from the chamber walls.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 7, 560–565 (10 October 1998) 相似文献
6.
Noise-induced escape from the basin of attraction of a strange attractor (SA) in a periodically excited nonlinear oscillator
is investigated. It is shown by numerical simulation methods that escape occurs in two steps: transfer of the system from
the SA to a close-lying saddle cycle along several optimal trajectories, and a subsequent fluctuation-induced transfer from
the basin of attraction of the SA along a single optimal trajectory. The possibility of using the results of this work to
solve problems of the optimal control of switchings from an attractor and for constructing theoretical estimates of the escape
probability is discussed.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 11, 782–787 (10 June 1999) 相似文献
7.
The formation of gas channels in rotating liquids is investigated and the application of such channels as capillaries for
high-power discharges in x-ray lasers, for transporting particle and radiation fluxes, and lowering breakdown thresholds (including
with the use of metal fillings), for structural systems for microwave generation and particle acceleration, and for photochemical
and shock action on a liquid, and so on, is discussed. It is noted that tubular active elements and samples can be fabricated
by solidification and crystallization during rotation.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 3, 291–294 (10 February 1997) 相似文献
8.
The quantum phase transition in clean itinerant ferromagnets is analyzed. It is shown that soft particle-hole modes invalidate Hertz's mean-field theory for d< or =3. A renormalized mean-field theory predicts a fluctuation-induced first order transition for 1相似文献
9.
Shaing KC 《Physical review letters》2001,86(4):640-643
It is demonstrated that besides the well-known toroidal momentum diffusion flux there is a pinchlike flux in the fluctuation-induced toroidal stress. A toroidal flow profile is determined up to a constant, e.g., the value of the flow at the magnetic axis, by balancing these two fluxes. The remaining residual toroidal stress determines the value of the flow at the axis. It is illustrated that the direction of the flow at the axis can change after plasma confinement is improved. The theory is applied to explain the toroidal flow reversal in tokamak experiments. 相似文献
10.
On December 3, 1996, in the time interval with low geomagnetic activity, the Interball-1 satellite crossed the neutral sheet of geomagnetic tail from north to south at the radial distance 25R
E. Characteristics of proton and electron fluxes 20 keV measured by DOK2 spectrometer are presented. High anisotropy of proton fluxes was observed. Fluxes of protons and their anisotropy are modulated by magnetic field. In a region where the total magnetic field is low and proton fluxes are high the anisotropy is lower and energy spectra of protons are harder than in another region. In the latter one (after 20:17 UT) when the total magnetic field is higher mainly due to an increase of |B
x
| (B
x
<0), DOK2 observes the increase of proton flux anisotropy. These fluxes have character of spikes. The detailed proton energy spectra shows that the spikes with duration of few seconds are characterised by very quick change of spectral slope. Proton spikes are accompanied by the increases of electron fluxes in the earthward direction. When B
x
>0, the proton fluxes in earthward direction predominate. In the time with B
x
<0 we observe the proton fluxes in the tail direction. This is in a good agreement with the measurements of bipolar fluxes on Geotail reported by Petrukovich et al. [J. Geophys. Res. 26 (1999) 2909]. We suppose that the cause of these bipolar proton fluxes is the reconnection of geomagnetic field lines during the growth phase of geomagnetic substorm. 相似文献
11.
A. I. Volokitin 《JETP Letters》2018,108(2):147-154
It has been shown that the rotation of a spherical nanoparticle with the radius R near the surface of a semi-infinite homogeneous medium can result in singular resonance in fluctuation-induced electromagnetic phenomena (Casimir force, Casimir friction, and radiative heat generation). Fluctuation electromagnetic effects increase strongly near this resonance even in the presence of dissipation in the system. The resonance occurs at distances of the particle from the surface d < d0R(3/4ε″1(ω1)ε″2 (ω2))1/3 (where ε″i(ωi) is the imaginary part of the dielectric function of the particle or the medium at the frequency of a surface phonon or plasmon polariton ωi), when the rotation frequency coincides with poles in the photon generation rate at Ω ≈ ω1 + ω2. These poles are due to the multiple scattering of electromagnetic waves between the particle and surface under conditions of the anomalous Doppler effect. These poles exist even in the presence of dissipation. At d < d0, depending on the particle rotation frequency, the Casimir force can change sign; i.e., the attraction of the particle to the surface changes to repulsion. The results can be important for the development of experimental methods for the detection of quantum friction. 相似文献
12.
Non-equilibrium molecular dynamics (NEMD) simulations are used to study the generation of heat fluxes in systems with spatially varying shear rates. We show that the kinetic temperature, when used in Fourier's law of heat conduction, does not correctly account for the heat flux, and that the normal temperature as described by Rugh (1997, Phys. Rev. Lett., 78, 772), should be used. Only in the absence of normal temperature gradients can heat fluxes due to strain rate coupling be correctly calculated. 相似文献
13.
The most general relativistic formulas for the tangential force of the fluctuation-electromagnetic interaction and the rate of thermal heating of a spherical neutral particle moving in vacuum near the surface of a condensed medium are obtained for the first time in dipole approximation. It is shown that the existence of a fluctuation-induced magnetic moment for a conducting particle is responsible for a considerable increase in the vacuum heat-exchange rate as compared to contact and radiative heat transfer (in accordance with the Stefan law). It is noted that the coincidence of the absorption peaks for the particle and the surface in the microwave range can explain the damping forces observed for nanoprobes in the dynamic mode of the atomic force microscope. 相似文献
14.
V. A. Schweigert V. M. Bedanov I. V. Schweigert A. Melzer A. Homann A. Piel 《Journal of Experimental and Theoretical Physics》1999,88(3):482-491
By employing the particle-in-cell method we study the distributions of the electric field strength and of the electron and
ion concentrations in the microparticle crystal in the electrode sheath in a radio-frequency discharge in helium. The coordinates
and charges of the microparticles are found from the balance condition for the forces acting on the particles and the balance
of electron and ion fluxes to the particles. With periodic boundary conditions introduced, we investigate the three-dimensional
problem for the unit cell of the microparticle crystal. We examine the dependence on gas pressure and discharge voltage of
the main crystal parameters: the critical particle separation (at which a phase transition from a monolayer crystal to a double-layer
crystal occurs), the particle potentials, and the distances between the layers in the double-layer crystal. We obtain the
critical values of the friction coefficient for the particles in the gas, i.e., values below which the crystal becomes unstable
against the development of particle oscillations in the transverse direction, and compare the experimental data on crystal
structure and stability with the theoretical results. Finally, we set up an approximate model that makes it possible to calculate
the main parameters of the microparticle crystal.
Zh. éksp. Teor. Fiz. 115, 877–893 (March 1999) 相似文献
15.
S. I. Lashkul A. B. Altukhov A. D. Gurchenko E. Z. Gusakov V. V. Dyachenko L. A. Esipov M. Yu. Kantor D. V. Kouprienko A. Yu. Stepanov A. P. Sharpjonok S. V. Shatalin E. O. Vekshina 《Czechoslovak Journal of Physics》2005,55(3):341-348
This paper deals with the new spectral and microturbulence experimental data and their analysis, which show that the radial electric field E
r generated at the lower hybrid heating (LHH) in the FT-2 is high enough to form the transport barriers. The ETB is formed when LHH is switched off. The radial fluctuation-induced E × B drift flux densities near LCFS in SOL are measured at two different poloidal angles. For this purpose two Langmuir probes located at low and high field sides of the torus are used. Registration of the poloidal and radial components of the electric field and density fluctuations at the same time during one discharge permits to measure the poloidal asymmetry of the transport reduction mechanism of the radial and poloidal particle fluxes in the SOL. The absolute
fluctuation levels show dependence on the sign of E
r shear. The modification of the microscale turbulence by the poloidal E
r × B rotation shear
E × B
at the L-H transition near LCFS is also studied by X-mode fluctuation reflectometry. The new data were obtained by spatial spectroscopic technique.Presented at the Workshop Electric Fields Structures and Relaxation in Edge Plasmas, Nice, France, October 26–27, 2004. 相似文献
16.
《Waves in Random and Complex Media》2013,23(4):269-286
Abstract In this paper we first derive the equations governing the energy fluxes propagating in each of the modes of a duct. In each mode there is a forward and backward component and the equations are intended to treat ducts in which backscattering plays a major role. The modal fluxes are coupled since there is transfer of energy between the modes that occurs as a result of random time and space sound-speed fluctuations in the medium in the duct. Since the fluctuations are both space and time dependent the governing equations are radiation transport equations. This is not the case if the fluctuations depend only on space. The basic method is to develop a coupled set of equations for the energy spectra in the modes and then to integrate over the frequency to obtain the fluxes. In the second section of this paper the modal flux equations are solved. A numerical result is presented to show how energy is transferred between modes. It is also shown how the reflected energy varies as a function of duct length. 相似文献
17.
Y. Izumida K. Okuda 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,77(4):499-504
We study a Brownian Carnot cycle introduced by Schmiedl
and Seifert [Europhys. Lett. 81, 20003 (2008)]
from a viewpoint of the linear irreversible thermodynamics.
By considering the entropy production rate of this cycle,
we can determine thermodynamic forces and fluxes of the cycle and calculate
the Onsager coefficients
for general protocols, that is, arbitrary schedules
to change the potential confining the Brownian particle.
We show that these Onsager coefficients contain the information of the
protocol shape and they satisfy the tight-coupling
condition irrespective of whatever protocol shape
we choose. These properties may give an explanation why the
Curzon-Ahlborn efficiency often appears in the finite-time heat engines. 相似文献
18.
Podestà M Fasoli A Labit B Furno I Ricci P Poli FM Diallo A Müller SH Theiler C 《Physical review letters》2008,101(4):045001
The mechanisms for anomalous transport across the magnetic field are investigated in a toroidal magnetized plasma. The role of plasma instabilities and macroscopic density structures (blobs) is discussed. Examples from a scenario with open magnetic field lines are shown. A transition from a main plasma region into a loss region is reproduced. In the main plasma, which includes particle and heat source locations, the transport is dominated by the fluctuation-induced particle and heat flux associated with a plasma instability. On the low-field side, the cross-field transport is ascribed to the intermittent ejection of macroscopic blobs propagating toward the outer wall. It is shown that instabilities and blobs represent fundamentally different mechanisms for cross-field transport. 相似文献
19.
E. I. Daibog K. Kecskemety Yu. I. Logachev 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(6):764-766
Exponential decay phases of electron and proton fluxes in solar energetic particle (SEP) events are investigated for the period
from 1974 to 2010 on the basis of IMP-8 and SOHO spacecraft data. The exponential decay of particle fluxes is possible under
the invariable integral properties of the surrounding space, which is homogeneous and quasi-stationary in a certain near-solar
sector. Consecutive events (sequences of events) with similar exponential decays allow these sectors of space homogeneity
to be expanded up to 90°, and sometimes up to 180° and more. 相似文献
20.
M. A. Zeldovich V. N. Ishkov Yu. I. Logachev K. Kesckemety 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(6):776-778
The ion abundances of charged particle fluxes with energies of 0.032–1.28 MeV/nucleon during the quiet period of solar activity
are investigated using spacecraft data. The values of Fe/O ratios obtained in 35 such periods in the 23rd solar cycle are
compared with the mean ion abundances in the solar corona, in the gradual and impulsive solar energetic particle events, and
in the solar wind. It is believed that coronal holes near the equator could be one of possible source of background low energy
particle fluxes. 相似文献