共查询到20条相似文献,搜索用时 15 毫秒
1.
Cha-Yeol Lee Ryoichi Yamashita Masaru Masuzaki 《International Journal of Infrared and Millimeter Waves》1997,18(2):519-535
We present, based on the cold fluid theory, linear analysis of the Cherenkov and cyclotron-Cherenkov instabilities which are
driven when a linear electron beam is injected into a dielectric-loaded waveguide immersed in an axial magnetic field. In
the analysis we consider azimuthally symmetric TM0n modes. We derive dispersion relations for three types of waveguide, and compare computationally obtained linear growth rates
of both instabilities. For the type A, which consists of a metallic cylinder with dielectric liner on its inner surface, the
growth rate of the Cherenkov instability is larger than that of the cyclotron-Cherenkov instability. For the type B, which
consists of a dielectric core and an outer metallic cylinder, both growth rates are comparable. And for the type C, which
consists of a metallic core with dielectric liner on its surface and an outer metallic cylinder, the growth rate of the latter
instability is higher than that of the former instability. Finally, for the type C, obtained are dependences of the oscillation
frequency and the growth rates of both instabilities on the following parameters: the beam energy, the beam current, the axial
magnetic field, the dielectric constant, and the thickness of the dielectric. 相似文献
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We study electromagnetic waves localized near the surface of a semi-infinite dielectric medium covered by a graphene layer in the presence of a strong external magnetic field. We demonstrate that a novel type of hybrid TE-TM polarized surface plasmons can propagate along the graphene layer. We analyze the effect of the Hall conductivity on the polarization properties of these hybrid surface waves and suggest a possibility to tune the graphene plasmons by the external magnetic field. 相似文献
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A new type of a linear relation between the components of the magnetic field vector and those of the elastic strain tensor (a dynamic piezomagnetic interaction) is proposed. This relation is irrespective of the crystal symmetry and of the presence of a magnetic structure in the dielectric medium. This leads to anomalies in the reflection of a beam of shear bulk waves incident from the depth of the nonmagnetic dielectric medium on either its mechanically free surface or its slip boundary with a semibounded magnetic medium. 相似文献
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The paper demonstrates existence of electromagnetic surface waves at the boundary separating a magnetized semiconductor plasma and a dielectric or metal. The external magnetic field is along the interface. As has been shown, slow surface waves of the helicon or Alfven type can exist only with their propagation vector directed obliquely with respect to the magnetic field. The ω-k relations have been found and ranges of existence established both in the frequency domain and that of angles between the propagation vector and the magnetic field. 相似文献
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D. V. Kulagin A. S. Savchenko S. V. Tarasenko 《Journal of Experimental and Theoretical Physics》2008,106(5):918-935
By an example of a semibounded one-dimensional magnetic photonic crystal (MPC) of easy-axis antiferromagnet-nonmagnetic dielectric type placed in mutually orthogonal dc magnetic and electric fields, conditions are found under which the quadratic magneto-optic interaction leads to a number of anomalies in the reflection and propagation conditions for TM or TE waves incident from outside on the surface of the superlattice. It is assumed that the easy magnetic axis is collinear to the electric field. 相似文献
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The possibility of the existence of a special class of surface electromagnetic waves with amplitude decreasing nonexponentially as they pass into an anisotropic metal–dielectric structure that borders the isotropic dielectric has been shown. The dispersion equation describing the propagation of such special surface waves has been obtained, and their attenuation coefficients and formula for electric and magnetic fields in contacting media have also been found. The expressions for the longitudinal and transverse components of the Poynting vector and volume density of electric and magnetic energy of special surface waves have been obtained. Numerical calculations for the layered metal–dielectric nanostructure that is described by a uniaxial tensor of effective dielectric permeability have been carried out Decaying. 相似文献
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It is shown that both TE and TM waves incident on the surface of a semi-infinite one-dimensional thin-layer gyrotropic magnetic
photonic crystal of the magnetic-nonmagnetic dielectric type can experience a number of refraction anomalies in an external
electric field due to the effect of hybridization of evanescent waves in magnetic and nonmagnetic layers. These anomalies
are absent under the same conditions in spatially homogeneous media consisting of the same materials as the photonic crystal. 相似文献
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Korzekwa R. Lehr F.M. Krompholz H.G. Kristiansen M. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1989,17(4):612-615
The influence of DC and pulsed magnetic fields on dielectric surface breakdown using pulsed test voltages is investigated for space conditions. Prediction from the saturated surface avalanche breakdown model and the experimental results show magnetic insulation effects i.e. an increase of the flashover voltage at magnetic-field amplitudes as low as 0.1 T. The insulation effects depend on the dielectric material, ambient pressure, surface roughness and presence of background plasma. In order to achieve magnetic insulation without a background plasma, it is sufficient to apply the magnetic field to the cathode region only 相似文献
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利用自编1D3V PIC程序,数值研究了不同外加磁场方式对次级电子倍增抑制的物理过程,给出了次级电子数目、平均能量、密度、运动轨迹、渡越时间、介质表面静电场及沉积功率等物理量时空分布关系。模拟结果表明:不同方向外加磁场抑制次级电子倍增的机理有所不同。轴向外加磁场利用电子回旋运动干扰微波电场对电子加速过程,使其碰壁能量降低以达到抑制二次电子倍增的效果;横向外加磁场利用电子回旋漂移过程中,电子半个周期被推离介质表面(不发生次级电子倍增),半个周期被推回介质表面(降低电子碰撞能量)的作用机理,达到抑制二次电子倍增的效果。讨论了横向磁场在回旋共振下,电子回旋同步加速导致回旋半径增大,电子能量持续增加的特殊过程。两种外加磁场方式都可以通过增加磁场达到进一步抑制次级电子倍增的目的。轴向外加磁场加载容易,但对磁场要求较高;横向外加磁场需要磁场较低,但加载较为困难。 相似文献
12.
Photodetachment microscopy of H~- in the magnetic field near different dielectric surfaces
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《中国物理 B》2015,(6)
We study the photo-detachment interference patterns of a hydrogen negative ion in the magnetic field near different dielectric surfaces with a semi-classical open orbit theory.We give a clear physical picture describing the photo-detachment of H-in this case.The electron flux distributions are calculated at various dielectric surfaces with unchanged magnetic field strength.It is found that the electron flux distributions of H-are very different in a magnetic field near different dielectric surfaces,namely the dielectric surface has a great influence on the photo-detachment interference pattern of the negative ion.Therefore,the interference pattern in the detached-electron flux distribution can be controlled by changing the dielectric constant.We hope that our studies may guide the future experimental research in photo-detachment microscopy. 相似文献
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使用时域有限差分法,研究了各向异性特异材料(AMM)作为包层的AMM/介质/AMM波导中表面等离子体的共振性质.色散关系表明,当特异材料为负磁导率的always-cutoff型时,AMM/介质/AMM波导支持TE极化的表面等离子体,表面等离子体的波长随着中间介质层的厚度和特异材料磁等离子体频率的减小而变短.在有限长度AMM/介质/AMM波导中,由于两端界面的反射,表面等离子体模在波导中形成Fabry-Perot共振,而实现亚波长的表面等离子体微腔.在共振频率,电场强度在微腔的中部达到最大值,而磁场分别在两端界面处达到最大,电磁能强局域在中间介质层中,这一性质将在可调的具有强局域特性的亚波长微腔及腔量子电动力学中具有潜在的应用. 相似文献
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A. I. Laptukhov 《Russian Physics Journal》1995,38(1):15-19
Explicit expressions have been found for the electric current density created in a solid dielectric due to inertial, di = mpole, and quadrupole polarizations of the molecules and atoms in the presence of an external magnetic field and a mechanical disturbance of the medium. We show the importance of considering these polarizations in explaining the electromagnetic radiation from microcracks in dielectric and the formation of surface electric charges in them whose values are the greater the lower the characteristic linear dimension of the microcracks.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 20–25, January, 1995. 相似文献
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利用闭合轨道理论, 研究了变化的磁场和不同电介质表面对氢负离子光剥离截面的影响, 并推导出了该体系下的光剥离截面公式. 结果发现, 氢负离子的光剥离截面不仅与磁场的强度有关, 而且还与电介质常数有关. 当氢负离子到电介质表面的距离和电介质常数一定时, 体系的光剥离截面中的振荡随磁场的变化而明显变化. 随着磁场强度的 增大, 体系的闭合轨道数目增多, 光剥离截面的振荡越来越复杂. 当氢负离子到电介质表面的距离和磁场强度一定时, 电介质常数的变化对光剥离截面的影响也很重要, 随着电介质常数的增大, 体系的闭合轨道数目增多, 光剥离截面的振荡也变得越来越复杂. 因此, 可以通过改变磁场强度和电解质常数来调整负离子的光剥离截面. 此结果 对于研究负离子体系在表面附近和外场中的光剥离问题具有一定的参考价值. 相似文献
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利用半经典开轨道理论,研究了GaAs电介质表面对氢负离子在磁场中的光剥离干涉图样的作用,推导并计算了本体系下的光剥离电子流通量,主要研究GaAs电介质表面到离子的距离不同对电子通量的影响。结果表明,电介质表面到离子的距离可以改变电子通量分布中的振荡结构,影响探测平面上形成的干涉图样的分布。因此,可以通过改变电介质表面到离子的距离来调控剥离电子的通量和干涉图样分布。 相似文献
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P.P. Hankare R.P. Patil U.B. Sankpal R. Sasikala I.S. Mulla 《Journal of magnetism and magnetic materials》2010,322(18):2629-9662
Nanocrystalline Li0.5Fe2.5−xCrxO4 (2.5≤x≥0) ferrites were prepared by a sol-gel autocombustion route. X-ray diffraction was employed to confirm the cubic spinel phase formation of the ferrites. The lattice parameter decreases with increase in Cr content. The saturation magnetization, coercivity and remanance were studied as a function of Cr content. The dielectric constant and dielectric loss were measured as a function of frequency in the frequency range 20 Hz-1 MHz. Frequency dependence of dielectric constant shows dielectric dispersion due to the Maxwell-Wagner type of interfacial polarization. In order to understand the conduction mechanism, complex impedance measurements were carried out. The substitution of chromium plays an important role in changing the dielectric and magnetic properties of lithium ferrites. 相似文献