共查询到20条相似文献,搜索用时 31 毫秒
1.
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
2.
Large amplitude electromagnetic solitons in intense laser plasma interaction 总被引:1,自引:0,他引:1 下载免费PDF全文
This paper shows that the standing, backward- and forward-accelerated large
amplitude relativistic electromagnetic solitons induced by intense laser pulse in
long underdense collisionless homogeneous plasmas can be observed by particle
simulations. In addition to the inhomogeneity of the plasma density, the
acceleration of the solitons also depends upon not only the laser amplitude but also
the plasma length. The electromagnetic frequency of the solitons is between about
half and one of the unperturbed electron plasma frequency. The electrostatic field
inside the soliton has a one-cycle structure in space, while the transverse electric
and magnetic fields have half-cycle and one-cycle structure respectively. Analytical
estimates for the existence of the solitons and their electromagnetic frequencies
qualitatively coincide with our simulation results. 相似文献
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The dispersion properties of potential surface waves (SW), propagating at a warm nonisothermal plasma-metal boundary across the external magnetic field are studied in this paper. The existence of potential SW is shown to be possible in frequency ranges, where electromagnetic SW do not exist. The influence of transverse plasma density inhomogeneity on dispersion properties of the SW considered is studied as well. 相似文献
5.
Q. Bai C. Liu J. Chen Y. X. Fan H. T. Wang 《Applied physics. B, Lasers and optics》2010,98(4):681-684
We present a scheme for achieving actively-controlled polarization independent extraordinary electromagnetic transmission
in one-dimensional subwavelength metal gratings. The key of this realization is to introduce high refractive index and magnetic
activity into the metal grating, in which the transverse electric polarized radiation can also be transmitted and the transmission
peaks can be actively tuned by applied magnetic field. The single mode theory and full wave electromagnetic simulation are
used to confirm our idea. 相似文献
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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.
We report the first demonstration of magnetically induced transmission in an opaque magnetized plasma. Magnetically induced transmission in a plasma is a classical analog to the electromagnetically induced transparency in atomic systems. The transmission of radiation through an axially magnetized plasma is obtained by applying an additional one dimensional transverse spatial periodic magnetic field. The transverse-periodic magnetic field uncouples the right-hand electromagnetic wave from interacting with plasma electrons, rendering the plasma band-stop transparent. This provides means to control the extent of absorption of electromagnetic radiation in magnetized plasma. 相似文献
9.
We propose a new scheme for realizing left-handed electromagnetic properties in a coherently driven four-level system. At the presence of spontaneously generated coherence and the local field effect, both dielectric permittivity and magnetic permeability may have negative real parts of the same order in a small frequency band. Thus, one can achieve the negative refractive index and then manipulate it by modulating the coherent field or changing the atomic density. With incoherent pumping applied to have more remarkable spontaneously generated coherence, one can further obtain a wider frequency band of negative refraction and simultaneously reduce the accompanied absorption. 相似文献
10.
用数值方法研究磁化非均匀等离子体(磁场与密度梯度垂直)中模转换机制对p极化电磁波的吸收效应,重点考虑磁场对吸收率的影响,结果表明:与非磁化等离子体相比,磁场的加入使得吸收率曲线相对入射角的分布发生小的偏移,吸收率为零的位置不是发生在零度入射(即垂直入射)时.而是在一个负的入射角位置,垂直入射时有不为零的吸收率,且正角度范围与负角度范围的峰值吸收率不相等,磁场提高了正入射角范围内的峰值吸收率而降低了负角度范围内的峰值吸收率(或反过来,这取决于磁场方向). 相似文献
11.
《Waves in Random and Complex Media》2013,23(3):383-397
In this paper the reflection index of an unsteady magnetized plasma slab irradiated by an electromagnetic wave is investigated. The direction of the external magnetic field is normal to the plasma surface. Here, it is assumed that the electromagnetic wave is normally incident on the gas slab. On the other hand, this gas slab is being ionized by another strong microwave field and the density of the unsteady plasma increases with time. The effects of the density growth rate, the thickness of the plasma slab and the external magnetic field on the reflection index are simulated. 相似文献
12.
《Waves in Random and Complex Media》2013,23(4):571-588
The reflection index of an unsteady moving magnetized plasma slab irradiated by an electromagnetic wave is investigated. The direction of the external magnetic field is parallel to the plasma surface and the electromagnetic wave is normally incident on a gas slab and produces the plasma. This gas slab is being ionized by another source and the density of the mentioned unsteady plasma increases with time. The effects of the density growth rate, velocity, thickness of the plasma slab, and the external magnetic field on the reflection index are simulated. 相似文献
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利用自行研制的2-1/2维全电磁柱坐标粒子模拟程序对等离子体融断开关磁场渗透机制进行了模拟研究。模拟结果表明在磁场Hall渗透机制特征长度远远小于等离子体离子的无碰撞趋肤深度的条件下,等离子体内部磁场渗透过程主要由电子流体运动的Hall项来控制。对于等离子体空间分布存在较大的密度梯度的物理问题,必须考虑二维空间特性对磁场渗透速度的影响。在磁场已渗透经过的等离子体区域中,等离子体呈现非电中性,离子受静电场的作用会加速运动到达阴极,最终形成真空鞘层。 相似文献
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分析了电磁波以任意角度入射到有限磁场中的激光等离子体通道天线(LPCA)时的电磁散射特性。根据LPCA的工作原理建立了其电磁分析模型,推导出广义柱坐标系下各向异性磁化等离子体中纵向分量所满足的波动方程和纵向场与横向场的关系,得到LPCA和周围媒质中的电磁场,利用边界切向电磁场连续,得出了散射系数方程。通过计算实例,将结果与文献结果比较,吻合较好。该研究结果预期可应用于高功率微波武器系统的研究。 相似文献
17.
J.?Kova?i? T.?Gyergyek M.??er?ek 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):383-389
We present some results of a one-dimensional fluid model with a floating electrode immersed in plasma with magnetic field
applied at an oblique angle. The model equations are integrated numerically in order to find the space profiles of the ion
velocities and electrostatic potential for various strenghts and angles of the magnetic field. We assume a collisionless magnetized
pre-sheath with isothermal ions. The results are then compared with the spatial profiles obtained by a computer simulation.
We use a BIT1 particle-in-cell code. The simulations input parameters are chosen in the way, that they resemble the fluid
model as much as possible. Because the results of the simulation are given in the absolute SI units, they have to be normalized
correctly. We evaluate the model results and compare them with the computer simulation results. Special attention is brought
on formation of the pre-sheath with magnetic field applied at intermediate angles. The results of the simulation are in good
qualitative agreement with the model. 相似文献
18.
Reza Fallah Reza Khooniki Seyed Mohammad Khorashadizadeh Ali Reza Niknam 《等离子体物理论文集》2021,61(2):e202000086
The influence of relativistic-ponderomotive nonlinearities and the plasma inhomogeneity on the nonlinear interaction between a high-power laser beam and a warm underdense plasma are studied. It is clear that the relativistic ponderomotive force and the electron temperature modify the electron density distribution and consequently change the dielectric permittivity of the plasma. Therefore, by presenting the modified electron density and the nonlinear dielectric permittivity of the warm plasma, the electromagnetic wave equation for the propagation of intense laser beam through the plasma is derived. This nonlinear equation is numerically solved and the distributions of electromagnetic fields in the plasma, the variations of electron density, and plasma refractive index are investigated for two different background electron density profiles. The results show that the amplitude of the electric field and electron density oscillations gradually increase and decrease, during propagation in the inhomogeneous warm plasma with linear and exponential density profiles, respectively, and the distribution of electron density becomes extremely sharp in the presence of intense laser beam. It is also indicated that the electron temperature and initial electron density have an impact on the propagation of the laser beam in the plasma and change the plasma refractive index and the oscillations' amplitude and frequency. The obtained results indicate the importance of a proper choice of laser and plasma parameters on the electromagnetic field distributions, density steepening, and plasma refractive index variations in the interaction of an intense laser beam with an inhomogeneous warm plasma. 相似文献
19.
An externally applied longitudinal magnetic field was found to enhance the particle trapping in the laser wakefield acceleration. When a static magnetic field of a few tens of tesla is applied in parallel with the propagation direction of a driving laser pulse, it is shown from two-dimensional particle-in-cell simulations that total charge of the trapped beam and its maximum energy increase. The analysis of electron trajectories strongly suggests that the enhanced trapping originates from the suppression of the transverse motion by the magnetic field. The enhanced trapping by the magnetic field was observed consistently for various values of the plasma density, the amplitude of the laser pulse and pulse spot size. 相似文献