共查询到20条相似文献,搜索用时 984 毫秒
1.
This paper attempts to introduce an effective mechanism of plasma heating of an overdense plasma layer. This mechanism is directly related to the phenomena of anomalous transparency of an overdense plasma layer. High temperature is achieved due to the resonant excitation of the coupled surface waves on both sides of the plasma layer. The dissipative energy of the collisional effects appears as an effective heating source in this mechanism. The solutions of the heat equation under the resonant situations are obtained in the steady and unsteady states conditions. The main factors, affecting the considered plasma heating mechanism, are also discussed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
2.
In the present Letter the transparency of a two-moving-magnetized-plasma-layer structure irradiated by an electromagnetic wave is investigated theoretically and its resonant conditions are determined. Here, the direction of the external magnetic field is normal to the plasma surface and two layers move with different velocities parallel to the interface. The effects of the external magnetic field, speed of plasma layers and the magnitude of the wave number component on transparency are simulated. These investigations for S-polarized and P-polarized electromagnetic waves have been done separately. 相似文献
3.
Yu. A. Kravtsov J. Chrzanowski 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,63(1):129-133
Polarization of electromagnetic waves in magnetized plasma is studied in conditions, when
Cotton-Mouton effect is weak enough as compared with Faraday one. Evolution of
polarization state is described by new mathematical approach, namely, by angular variables
technique (AVT) which describes evolution of the angular parameters of polarization
ellipse in magnetized plasma. The method of consequent approximations is applied, which
uses the ratio (Ω
⊥/Ω
3) of
Cotton-Mouton and Faraday terms, as a small parameter of a problem and allows obtaining
simple analytical expressions for azimuthal and ellipticity angles in frame of the first
and second approximations. The phenomenon of ellipticity modulation and suppression by
Faraday rotation is revealed, which consists in ellipticity decreasing for stronger
Faraday rotation, what makes polarization closer to linear one. Numerical illustration of
the phenomenon are presented. It is shown that account of the second-order terms of the
method of consequent approximation provides an accuracy better than 1% even in conditions,
when small parameter
Ω
⊥/Ω
3
achieves the value 1/4. 相似文献
4.
V.I. Belotelov L.L. Doskolovich V.A. Kotov E.A. Bezus D.A. Bykov A.K. Zvezdin 《Optics Communications》2007,278(1):104-109
A significant enhancement of the magnetooptical Faraday effect in the bilayer heterostructure of a thin metallic layer pierced by an array of parallel subwavelength slits and a uniform dielectric layer magnetized perpendicular to its plane, is reported. Calculations, based on the rigorous coupled-wave analysis of Maxwell’s equations, demonstrate that in such structures the Faraday effect spectrum has several resonance peaks in the near-infrared range, some of them coinciding with transmittance peaks, providing simultaneous large Faraday rotation enhanced by an order and high transmittance of about 35%. It is shown that the excitation of the quasi-guided TM- and TE-modes in the dielectric layer mostly governs the enhancement of the Faraday rotation. 相似文献
5.
6.
This paper suggests a new mechanism for the nonlinear transparency of a dense magnetized plasma slab. It is shown that a significant part of the radiation can penetrate the slab due to parametric excitation of surface waves. 相似文献
7.
Tang D.L. Sun A.P. Qiu X.M. Chu P.K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2003,31(3):405-410
The absorption, reflection, and transmission of electromagnetic waves by a nonuniform plasma slab immersed in an ambient uniform magnetic field of various strengths are studied in this paper. The effects of the plasma parameters and magnetic field strength on the absorbed, reflected, and transmitted power are discussed. The magnetized nonuniform plasma slab is modeled by a series of magnetized uniform plasma subslabs. The calculation results show that the effects of the magnetic field strength and density gradient on the absorbed power, as well as the frequency band of resonant absorption, are significant. A complete analysis utilizing the scattering matrix method is also used to compare the above calculation results which neglect multiple reflections between subslab interfaces. Broadband absorption of electromagnetic waves can be achieved by changing the magnetic field strength and plasma density. More than 90% of the electromagnetic wave power can be absorbed in a magnetized nonuniform plasma slab with width of 12 cm and the absorption bandwidth can range from 1 to 20 GHz with different plasma parameters and external magnetic field strengths. 相似文献
8.
9.
The theoretical properties of a composite chiral-plasma medium are developed. By using the reaction theorem for a magnetized
chiroplasma, we obtain the proof of nonreciprocity based upon the constitutive relationships between electromagnetic vectorsE, B, H, D. Using the Maxwell’s equations and the proposed constitutive relations for a chiral-plasma medium, we derive the vectorsE andH and from these equations, dispersion relations andE-field polarizations are based. The obtained results for waves propagating parallel to the external magnetic field in a cold
magnetized chiro-plasma are compared with typical results obtained for a cold plasma. For circulary polarized waves, a new
mode conversion is founded with the chiral effect. The chiral rotation is obtained and compared with the Faraday rotation.
For waves propagating across the magnetic field, we found a shift of the cut-offs of ordinary and extraordinary waves. On
the lower branch of the extraordinary wave mode there is no bands of forbidden frequencies and the reflection point vanishes
when the chiral parameter increases. 相似文献
10.
The dispersion of electromagnetic waves in waveguides partially filled with semiconductor plasma is investigated for unmagnetized and for strongly magnetized plasma. The effects which may be useful for the plasma electronics are found: In such waveguides there exist a large number of slow waves with typical frequencies ω ≈ ωP/√?L. The filling at which the different modes at fixed phase velocity are maximum separated in wavelength is found. The thickness of the semiconductor layer at which this effect arises is about hundred micrometers and depends on the crystals' type. In addition to this, in strongly magnetized semiconductor plasma the maximum frequency separation of the typical plasma waves is found at fixed filling. Is it shown that in such systems there exist many surface waves which are of the slow wave type. In the case of strongly magnetized plasma coupling between nonsymmetrical EH- and HE- modes is shown to exist. 相似文献
11.
The linear and non‐linear dynamics of ion acoustic waves are investigated in three‐component magnetized plasma consisting of cold inertial ions and non‐thermal electrons and positrons. The non‐thermal components are modelled by the hybrid distribution, representing the combination of two (kappa and Cairn's) non‐thermal distributions. The relevant processes, including the slow rotation of plasma along the magnetic field axis and collision between ions and neutrals, are taken into consideration. It is shown that the non‐linear dynamics of the considered system are governed by the Zakharov–Kuznetsov equation in modified form. In the general dissipation regime, the effects of the two non‐thermal distributions on the solitary waves are compared. The effects of other plasma parameters, such as collisional and rotational frequency, are also discussed in detail. 相似文献
12.
Extraordinary Electromagnetic Waves in Weakly Relativistic Degenerate Spin-1/2 Magnetized Quantum Plasmas
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By using the relativistic quantum magnetohydrodynamic model, the extraordinary electromagnetic waves in magnetized quantum plasmas are investigated with the effects of particle dispersion associated with the quantum Bohm potential effects, the electron spin-1/2 effects, and the relativistic degenerate pressure effects. The electrons are treated as a quantum and magnetized species, while the ions are classical ones. The new general dispersion relations are derived and analyzed in some interesting special cases. Quantum effects are shown to affect the dispersion relations of the extraordinary electromagnetic waves. It is also shown that the relativistic degenerate pressure effects significantly modify the dispersive properties of the extraordinary electromagnetic waves. The present investigation should be useful for understanding the collective interactions in dense astrophysical bodies,such as the atmosphere of neutron stars and the interior of massive white dwarfs. 相似文献
13.
A multiple scales technique is employed to solve the fluid-Maxwell equations describing a weakly nonlinear circularly polarized electromagnetic pulse in magnetized plasma. A nonlinear Schrödinger-type (NLS) equation is shown to govern the amplitude of the vector potential. The conditions for modulational instability and for the existence of various types of localized envelope modes are investigated in terms of relevant parameters. Right-hand circularly polarized (RCP) waves are shown to be modulationally unstable regardless of the value of the ambient magnetic field and propagate as bright-type solitons. The same is true for left-hand circularly polarized (LCP) waves in a weakly to moderately magnetized plasma. In other parameter regions, LCP waves are stable in strongly magnetized plasmas and may propagate as dark-type solitons (electric field holes). The evolution of envelope solitons is analyzed numerically, and it is shown that solitons propagate in magnetized plasma without any essential change in amplitude and shape. 相似文献
14.
L. Celona S. Gammino F. Maimone D. Mascali N. Gambino R. Miracoli G. Ciavola 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(1):107-115
Ion sources have a significant number of applications in accelerator facilities and in industrial applications. In particular,
the electron cyclotron resonance ion sources (ECRIS) are nowadays the most effective devices that can feed particle accelerators
in a continuous and reliable way, providing high current beams of low and medium charge state ions and lower, but still remarkable,
beam current for highly charged ions. In recent years several experiments have shown that the current, the charge states and
even the beam shape change by slightly varying the microwave frequency (the so-called frequency tuning effect – FTE). The
theoretical explanation of these results is based on the difference in the electromagnetic field pattern over the resonance
surface, i.e. that region where the electrons resonantly interact with the incoming wave. In order to be consistent with the
experiments, this model requires that standing waves are formed also in presence of a dense plasma. The proof was sought by
means of a series of measurements performed with a network analyzer and with a plasma reactor operating at 2.45 GHz, according
to the principles of the microwave discharge ion sources (MDIS). The measurements have been carried out with the aim to achieve
the electromagnetic characterization of the plasma chamber in terms of possible excited resonant modes with and without plasma,
and they reported that resonant modes are excited inside the cavity even in presence of a dense plasma. It was observed that
the plasma dynamics strongly depends on the structure of the standing waves that are generated. The measurement of the eigen-frequencies'
shifts were carried out for several values of pressure and RF power, thus linking the shift with the plasma density measured
by a Langmuir probe. The changes in plasma shape, density and electron temperature have been also monitored for different
operating conditions. A strong variation of plasma properties has been observed as a consequence of the introduction of the
Langmuir probe inside the resonant cavity, thus demonstrating that the standing wave can be strongly perturbed even by means
of relatively small metallic electrodes. The measurements reported hereinafter are relevant also for ECRIS, because they confirm
the validity of the theoretical model that describes the frequency tuning. 相似文献
15.
V. A. Kosobukin 《Physics of the Solid State》2006,48(11):2209-2215
A theory of electromagnetic wave propagation in structures formed by alternating magnetic and dielectric layers is proposed. Models of macroscopically thick and atomically thin layers magnetized perpendicular to their plane are considered. Transfer matrices of circularly polarized waves and characteristics of light propagation in periodic magnetic structures under normal incidence are obtained by the self-consistent electrodynamic Green’s function method in analytic form. The results obtained are employed to analyze linear-in-magnetization magneto-optical effects in the transmittance and reflectance spectra of one-dimensional magnetic Bragg structures called magnetophotonic crystals. For structures of finite thickness, Faraday rotation and other observable magneto-optical quantities are shown to vary appreciably in the spectral region of the stop bands of a magnetophotonic crystal. This is paralleled by a substantial enhancement of the magnetic-fieldinduced modulation of the reflectance of light polarized in the analyzer plane. 相似文献
16.
The stability of high‐frequency potential surface waves at a dense magnetized plasma – metal interface with respect to a low‐frequency plasma density modulation is studied in the point of view of the surface waves control. The discussion is addressed to the situation, when an external steady magnetic field is directed perpendicularly to the interface. The nonlinear interaction process of the high‐frequency surface wave, its satellites and the low‐frequency plasma density perturbation is investigated. It is shown that the low‐frequency plasma density perturbation can be represented as a superposition of forced waves of surface and volume types and can lead to an additional attenuation of the surface waves. This attenuation arises when the surface wave amplitude exceeds the threshold value. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
17.
18.
The influence of a magnetic defect on the field distribution and magneto-optical properties of a one-dimensional photonic crystal has been investigated. It has been shown that the maximum localization of the wave field in the defect layer is achieved in an asymmetric photonic crystal structure. A greater Faraday rotation, which significantly exceeds the angle of rotation of the polarization plane in an isolated magnetized layer, and a higher degree of localization of the wave field can be achieved when the magnetic layer is surrounded by layers of photonic crystal mirrors with a lower refractive index. An increase in the Faraday rotation angle is determined not only by an increase in the thickness of the magnetic defect but also by a symmetric increase in the number of periods in the photonic crystal mirrors. 相似文献
19.
Nadja Vogel 《Applied Surface Science》2006,252(13):4850-4856
We present results where highly supersonic plasma jets and accelerated plasma fragments are generated by interaction of an intense picosecond laser pulse with a metallic target (Al, Cu, W, and Ta) in gas atmosphere. The formation of jets and well-localized massive plasma fragments occurs when a strong forward shock from a main laser pulse and a reverse shock from a pre-pulse meet to. Interferometric and shadow graphic measurements with high temporal (100 ps) and spatial (1 μm) resolution yield information about the formation and evolution of plasma jets and plasma fragments. The excitation of the electric and self-generated magnetic field by ponderomotive force during propagation of the laser pulse in a gas atmosphere was investigated as well. It had been shown previously that under certain conditions a hollow current channel can be generated in laser-produced plasma. The azimuthal magnetic field in such a micro-channel was determined by Faraday rotation of a probing laser beam to be 7.6 MGauss (MG). Ion acceleration in a pinched annular current channel up to 8 MeV analogous to micro-“plasma focus” conditions, may be realized at lengths of 100 μm. Self-generated magnetic fields of 4-7 MG have also been measured in thin skin layers in front of shock waves, where well-collimated plasma blocks were separated and accelerated away from the plasma body. The velocity of dense plasma blocks reaches values of order of 3 × 108 cm/s and they are stable during acceleration and propagation in gas. 相似文献
20.
V. G. Gavrilenko A. A. Semerikov G. V. Jandieri 《Waves in Random and Complex Media》1999,9(3):427-440
Multiple scattering of electromagnetic waves by a plane layer of a turbulent magnetized collision plasma is considered. The influence of the distance between both the emitter and the receiver and the layer boundaries is analysed. It is found that the width of the angular spectrum of the received radiation for sufficiently strong absorption in the plasma is greater than in the collisionless plasma; the spectral maximum is substantially displaced with respect to the direction of the source. It is shown that these effects are weakened when the emitter approaches the layer. The relationship between the spectral width and also the displacement of its maximum and the distance from the receiver to the layer boundary may be substantially non-monotonic. 相似文献