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Woodruff S Hill DN Stallard BW Bulmer R Cohen B Holcomb CT Hooper EB McLean HS Moller J Wood RD 《Physical review letters》2003,90(9):095001
By operating a magnetized coaxial plasma gun continuously with just sufficient current to enable plasma ejection, large gun-voltage spikes (approximately 1 kV) are produced, giving the highest sustained voltage approximately 500 V and highest sustained helicity injection rate observed in the Sustained Spheromak Physics Experiment. The spheromak magnetic field increases monotonically with time, exhibiting the lowest fluctuation levels observed during formation of any spheromak (B/B>/=2%). The results suggest an important mechanism for field generation by helicity injection, namely, the merging of helicity-carrying filaments. 相似文献
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The magnetized-plasma contribution to the neutrino anomalous magnetic moment is calculated. It is shown that, in a magnetized
plasma, only part of the neutrino additional energy associated with the neutrino spin and with the magnetic-field strength
contributes to the neutrino magnetic moment. It is found that, in contrast to results presented previously in the literature,
the presence of a magnetized plasma does not lead to a substantial enhancement of the neutrino magnetic moment. 相似文献
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A. V. Kudrin L. E. Kurina E. Yu. Petrov 《Journal of Experimental and Theoretical Physics》2001,92(6):969-978
An investigations is made of the steady-state structure of a plasma inhomogeneity arising as a result of high-frequency heating and additional ionization of a background magnetized plasma by the near-zone field of a magnetic-type source (ring electric current). It is assumed that the source axis is parallel to an external magnetic field; the source frequency belongs in the low hybrid band. The main attention is focused on the particular case (important for possible applications) when the characteristic longitudinal and transverse scales of density distribution considerably exceed the corresponding scales of distribution of the electron temperature and of the source field. Simplified equations for the near-zone field of the source, the electron temperature, and the plasma density are written for this particular case. Based on the numerical solution of these equations, steady-state distributions of plasma parameters in the formed plasma inhomogeneity are found. It is demonstrated that a plasma inhomogeneity proves to be markedly extended along the external magnetic field. It is found that, for the values of the source current that are attainable under the conditions of active ionospheric and model laboratory experiments, the maximum plasma density in a nonuniform plasma may appreciably exceed the background value. 相似文献
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V. G. Gavrilenko G. V. Jandieri N. G. Pirtzkhalaishvili A. A. Semerikov 《Radiophysics and Quantum Electronics》1999,42(4):302-314
We consider multiple scattering of electromagnetic waves by a layer of turbulent magnetized collisional plasma. The influence
of the distances from the layer's boundaries to the emitter and receiver is analyzed. We find out that, provided absorption
in the plasma is strong enough, the width of the angular spectrum of the received radiation can be larger than in the collisionless
plasma, and the maximum of the spectrum is substantially shifted with respect to the direction to the source. It is shown
that these effects weaken as the emitter approaches the layer. The dependence of the width of the spectrum and the shift of
its maximum on distance from the receiver to the layer's boundary can be substantially nonmonotonic.
Lobachevsky State University, Nizhny Novgorod, Russia; Georgian Technical University, Tbilisi, Georgia. Translated from Izvestiya
Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol.42, No. 4, pp. 340–354, April 1999. 相似文献
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We investigate the effects of an external magnetic helicity production on the evolution of the cosmic axion field. It is shown that a helicity larger than (few x 10(-15) G)2 Mpc, if produced at temperatures above a few GeV, is in contradiction with the existence of the axion, since it would produce too much of an axion relic abundance. 相似文献
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N. A. Silant’ev 《Journal of Experimental and Theoretical Physics》1999,89(1):45-55
In this paper the procedure of large-scale averaging of the magnetic-field diffusion equation with the α-term curlα(r,t)B(r,t) is used to show that a nonuniform distribution of the turbulent helicity fluctuations (more precisely, the fluctuations
of the coefficient α) with a zero average value gives rise to large-scale amplification of the initial magnetic field. A detailed study is carried
out of the dependence of the resulting large-scale α effect on the characteristics of the correlator 〈〈α(r, t)α(r″,t″)〉〉 in a rotating medium with a nonuniform distribution of the angular velocity ω=ω(ρ,z) (ρ is the distance for the rotation axis z). The effect of helicity fluctuations and the diffusion coefficient on the turbulent diffusion process is also investigated.
Zh. éksp. Teor. Fiz. 116, 85–104 (July 1999) 相似文献
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The dependence of the shape of an ultrasonic pulse transmitted through a magnetized magnetic colloid on the angle between the wave vector and the magnetic induction vector is investigated. 相似文献
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The particle confinement in a magnetized plasma torus with superimposed vertical magnetic field is modeled and measured experimentally. The formation of an equilibrium characterized by a parallel plasma current canceling out the grad B and curvature drifts is described using a two-fluid model. Characteristic response frequencies and relaxation rates are calculated. The predictions for the particle confinement time as a function of the vertical magnetic field are verified in a systematic experimental study on the TORPEX device, including the existence of an optimal vertical field and the anticorrelation between confinement time and density. 相似文献
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Raman R Jarboe TR Nelson BA Izzo VA O'Neill RG Redd AJ Smith RJ 《Physical review letters》2003,90(7):075005
The first successful results on the transfer of a coaxial helicity injection (CHI) produced discharge to inductive operation are reported. CHI-assisted plasma startup is more robust than inductive only operation. After hand off for inductive operation, the initial 90 kA of CHI-produced current drops to 40 kA, then ramps up to 170 kA, using only 30 mV s, more than 30% higher than that produced by induction alone. These significant performance enhancing results were obtained on the HIT-II spherical torus experiment (major/minor radius of 0.3/0.2 m). 相似文献
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We argue that the magnetic helicity conservation is violated at the lepton stage in the evolution of early Universe owing
to the parity violation in the Standard Model of electroweak interactions. As a result, a cosmological magnetic field which
can be a seed for the galactic dynamo obtains from the beginning a substantial magnetic helicity which has to be taken into
account in the magnetic helicity balance at the later stage of galactic dynamo. The particle physics mechanism suggested in
our works depends neither on helicity of matter turbulence with plasma vortices resulting in the standard α effect in dynamo theory nor on general rotation. The mechanism can result in a self-exitation of an (almost) uniform cosmological
magnetic field.
The text was submitted by the authors in English. 相似文献
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Taylor JB 《Physical review letters》1989,63(13):1384-1385
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We present a theory of emission of electromagnetic waves, in the ordinary and extraordinary modes, in the presence of Langmuir turbulence in a magnetized plasma due to a high frequency nonlinear force. The mechanism of emission considered is the plasma-maser interaction which is essentially an energy up-conversion process. The growth rates of the ordinary and extra-ordinary mode emissions are calculated and the results are compared with those obtained from the direct formulation. The scope of application of the results to radio spectra from solar flares is then stressed.M.C. College, India. College of General Education, Kyushu University, Ropponmatsu, Japan. Gauhati University, India. Published in Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 5, pp. 548–562, May, 1994. 相似文献