共查询到20条相似文献,搜索用时 0 毫秒
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A new experiment has been constructed to study the sustainment of a field-reversed configuration (FRC) with a rotating magnetic field (RMF). FRCs were formed with cold, unmagnetized ions and thus without a kinetic ion component that was believed to provide stability to internal tilt modes. No destructive instabilities were observed for the RMF FRC. Only peripheral radial penetration of the RMF was observed. The radially inward flow arising from axial screening currents at the FRC edge reduced convective and conductive losses to the measurement limit of the diagnostics. 相似文献
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M. M. Rezinkina 《Technical Physics》2009,54(8):1092-1101
A method for numerical calculation of the magnetic field and magnetic moment of 3D ferromagnetic objects is described using
the method of finite volume and absorbing boundary conditions. The magnetic moments and magnetic field of some ferromagnetic
systems imitating various objects are calculated. It is shown that the configuration of ferromagnetic structures consisting
of various combinations of rods determines their magnetic moments. 相似文献
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Dubrouil A Mairesse Y Fabre B Descamps D Petit S Mével E Constant E 《Optics letters》2011,36(13):2486-2488
We demonstrate controlled high-order harmonic generation in gas using high-energy femtosecond pulses (50 fs-50 mJ on target) by performing spatial shaping of the terrawatt fundamental laser beam. We have developed a two optical paths mirror that can withstand high power and shape the pump beam into a quasi-flat-top profile (super Gaussian) near focus. We observe clear signatures of the spatial shaping on the harmonic beam in terms of profile, divergence, level of signal, and spectrum. The harmonic generation in neon with a quasi-flat-top beam results in a broadband extreme UV beam with extremely low divergence (~340 μrad). 相似文献
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Following the techniques used by Letelier and Stachel some new physically relevant stationary solutions of string cosmology
with magnetic field are presented. In these solutions, the flow vector of matter has non-zero rotation and the cosmological
constant is taken to be non-zero. Previously known solutions are derived as particular cases from our class of solutions.
Some string models with vanishing cosmological constant are also discussed. 相似文献
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A. D. Abramov 《Russian Physics Journal》1971,14(1):25-28
The eddy-current loss is calculated for nonferromagnetic disks in a rotating magnetic field. The power loss is found as a function of the magnetic field intensity, the field rotation velocity, and the disk dimensions. The eddy-current loss was measured experimentally in rotating fields in copper, aluminum, and zinc disks; a good agreement was found with the calculated values.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 38–42, January, 1971. 相似文献
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The stability of a uniformly rotating cylindrical plasma configuration in dynamical equilibrium is discussed. Assuming an axial current and sheet currents for the plasma, we have obtained a dispersion relation for non-axisymmetric perturbations. The dispersion relation comes out to be a complex and implicit function of the frequency of perturbations. Here we have discussed the dispersion equation for the modem=1, with the help of numerical computations. It has been shown that rotation has a stabilizing influence, whereas the axial current destabilizes the cylinder. 相似文献
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N. S. Erokhin M. I. Kopp F. Kh. Khakimov Sh. Shokirov 《Radiophysics and Quantum Electronics》1989,32(4):305-309
Tadzhik State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 32, No. 4, pp. 405–410, April, 1989. 相似文献
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Heat generation by viscous dissipation in a dilute suspension of single-domain ferromagnetic particles in a rotating magnetic
field is analyzed by assuming that the suspended particles have a high magnetic rigidity. The problem is solved by using a
kinetic approach based on a rotational diffusion equation. Behavior of specific loss power (SLP) as a function of field strength
H and frequency ω is examined at constant temperature. SLP increases as either of these parameters squared when the other is
constant, eventually approaching a saturation value. The function SLP(H, ω) can be used to determine optimal and admissible ranges of magnetically induced heating. 相似文献
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Bang-Jun Che Guo-Hui Yang Fan-Yi Meng Kuang Zhang Jia-Hui Fu Qun Wu Li Sun 《Applied Physics A: Materials Science & Processing》2014,116(4):1579-1586
In this paper, omnidirectional wireless power transfer (OWPT) via magnetic resonant coupling is proposed based on rotating magnetic field. In contrast to conventional WPT, the proposed wireless power transmitter consists of two orthogonal loops with 90° feeding phase difference. Both theoretical analyses and numerical simulations show that such transmitter generates rotating magnetic field and can provide wireless power to multiple receivers moving around it. In addition, a cylindrical metamaterial slab with negative permeability is used to improve the efficiency of the OWPT system, for the unique property of enhancing evanescent wave of metamaterials. It is shown that the efficiency of the OWPT can be improved to more than five times of that of the original one by the metamaterial slab. 相似文献
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The trajectories of ions confined in a field-reversed configuration (FRC) equilibrium magnetic geometry and heated with a small-amplitude, odd-parity rotating magnetic field (RMF) have been studied with a Hamiltonian computer code. When the RMF frequency is in the ion-cyclotron range, explosive heating occurs. Higher-energy ions are found to have betatron-type orbits, preferentially localized near the FRC's midplane. These results are relevant to a compact magnetic-fusion-reactor design. 相似文献
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《Physics letters. A》1988,127(5):263-266
A new axial gas discharge stabilization technique is described. Thermal instabilities and discharge constrictions are suppressed through the use of a transverse rotating magnetic field. The enhanced plasma stability observed is a result of a transverse Lorentz force that deflects the plasma column off-axis. As the magnetic field rotates, the plasma sweeps across the tube cross-section at the angular velocity of the impressed field. A 25% increase in power loading has been achieved using the stabilization technique. 相似文献
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A. Cēbers 《Journal of magnetism and magnetic materials》2011,323(3-4):279-282
Swimming trajectory of a magnetotactic bacterium in a rotating magnetic field is a circle. Random reversals of the direction of the bacterium motion induces a random walk of the curvature center of the trajectory. In assumption of the distribution of the switching events according to the Poisson process the diffusion coefficient is calculated in dependence on the frequency of the rotating field and the characteristic time between the switching events. It is confirmed by the numerical simulation of the random walk of the bacterium in the rotating magnetic field. 相似文献
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Brugnera L Frank F Hoffmann DJ Torres R Siegel T Underwood JG Springate E Froud C Turcu EI Tisch JW Marangos JP 《Optics letters》2010,35(23):3994-3996
We demonstrate enhancement by 1 order of magnitude of the high-order harmonics generated in argon by combining a fundamental field at 1300 nm (10(14) W cm(-2)) and its orthogonally polarized second harmonic at 650 nm (2 × 10(13) W cm(-2)) and by controlling the relative phase between them. This extends earlier work by ensuring that the main effect is the combined field steering the electron trajectory with negligible contribution from multiphoton effects compared to the previous schemes with 800/400 nm fields. We access a broad energy range of harmonics (from 20 eV to 80 eV) at a low laser intensity (far below the ionization saturation limit) and observe deep modulation of the harmonic yield with a period of π in the relative phase. Strong field theoretical analysis reveals that this is principally due to the steering of the recolliding electron wave packet by the two-color field. Our modeling also shows that the atto chirp can be controlled, leading to production of shorter pulses. 相似文献