Theoretical Analysis of the Resonance Cone in an Inhomogeneous Magnetoplasma Column

The three-dimensional behavior of the high-frequency resonance cone is investigated using an inhomogeneous slab magnetoplasma model under the quasi-static approximation and neglecting ion motion. The effects of finite ky and electron thermal motion are considered numerically, revealing that the cone angle is shifted to a slightly smaller angle and the reflection point is also shifted toward the high density region compared with results under the cold plasma approximation.     

Radiated Electromagnetic Waves in an Inhomogeneous Magnetoplasma near the Upper Hybrid Frequency

Properties of several plasma waves in a wavenumber space are investigated in a hot magnetized plasma. The properties are applied to investigate ray trajectories of radiated electromagnetic waves to an inhomogeneous plasma and mode conversion of the extraordinary mode into electrostatic cyclotron harmonic waves at the upper hybrid frequency layer. The wave fronts of the mode-converted cyclotron harmonie wave from the extraordinary wave are made clear. Furthermore, ray trajectories of radiated cyclotron harmonic waves and the mode-converted extraordinary mode are obtained.     

Penetration of Localized Radio Frequency Fields through an Inhomogeneous Magnetoplasma

Penetration and bending of localized RF fields, namely, the high-frequency resonance cone, through an inhomogeneous magnetoplasma are confirmed experimentally and are explained from a cold plasma theory.     

Coherent and Incoherent Contributions to the Damping of Cyclotron Magnetoplasma Resonance for Two-Dimensional Electrons

The spectrum of resonant microwave absorption for a two-dimensional electron disk is studied by the optical detection technique. The dependence of the width of cyclotron magnetoplasma resonance on the electron density and on the size of the two-dimensional electron system is analyzed. The contributions of the coherent radiative and incoherent collision mechanisms to the relaxation of magnetoplasma excitations are measured. It is demonstrated that the ratio of the length of the electromagnetic wave and the lateral size of the twodimensional electron system is an important parameter determining the width of the resonance.     

Kelvin Helmholtz Instability in a Magnetoplasma

Two dimensional transverse Kelvin-Helmholtz (K-H) instability has been studied at the interface between the two fluids (plasma medium) of finite thickness in relative motion to each other. The perturbations on the interface are assumed to be electromagnetic and a dispersion relation is obtained. The interface (boundary) has been found to be unstable for a wide range of perturbation wavelengths (wave numbers kx, ky). It is shown that the modification introduced by electromagnetic (quasi-electrostatic) perturbations in comparison to electrostatic one is to reduce the growth rate of perturbations. The growth rate maximizes when kx = ky. The applications of this study have been discussed to explain some of the observed ionospheric (auroral arc formation) and magnetospheric (unstable magnetopause boundary, hydromagnetic pulsations) phenomena.     

The Millimeter Band Oscillator in the Large-Orbital Resonance Mode

The millimeter band oscillator operating in the specific large-orbital resonance mode is considered. A theoretical analysis of energy oscillator characteristics is made. According to the early estimates, this system is free from some shortcomings typical for a gyro-devices when an operating wavelength becomes shortened to a millimeter and submillimeter band.     

Cross Spectral Measurements in a Quiescent Magnetoplasma

The low frequency cross spectrum of electron density fluctuations in a weakly ionized magnetoplasma is measured with two Langmuir probes aligned transverse to the static magnetic field. The shapes of the observed cross spectra are exponentionally damped cosines as predicted by theory. However, the frequency of the first zero crossing of the cross spectra is strongly dependent on probe bias.     

Antenna Performance of a Directly Dug Corrugated Feedhorn for the 150-GHz Band

We have developed a 150 GHz band corrugated feed horn. These corrugated feed horns have been established by a new machining method, which involves digging corrugations through a metal material. We were able to realize E plane and H plane symmetry, low side lobe level, and low cross-polarization level. Measured co-polarization beam patterns above − 35 dB were consistent with the simulated patterns within a designed frequency range. The peak levels of cross-polarization beam patterns were less than − 30 dB. And, the performances were uniform in several horns. In the present paper, we describe the corrugated horn produced by this methods.     

Investigation of Plasma Parameters in a Magnetoplasma Compressor

The article presents the results of experimental investigations that were carried out at the Center for Science and Technology Development in Belgrade (Yugoslavia) and pertained to the plasma streams generated by a gasdischarge magnetoplasma compressor (MPC). The integral characteristics of the discharge, the dynamic parameters of a compression flux, and the concentration of the plasma electrons in the magnetoplasma compressor have been determined. The distinguishing features of the discharge afterglow from the volume of a vacuum chamber for a long time after the termination of the discharge current have been investigated.     

Frequency （Stochastic） Resonance and Stochastic Resonance for a Superconducting Junctions＇ Device

In this paper, we investigate a Josephson-junction device with dichotomous resistance or a special SQUID （superconducting quantum interference device）. It is shown that frequency （stochastic） resonance and stochastic reso- nance can appear for some suitably selected parameters＇ values of the device respectively. Our results can provide some insights for the investigation of the SQUID response to the signal （including the input alternating current, the added al- ternating voltage, the vertically added alternating magnetic field, and the detected （electric-magnetic） temporal-periodic signal）.     

Frequency in Middle of Magnon Band Gap in a Layered Ferromagnetic Superlattice

The frequency in middle of magnon energy band in a five-layer ferromagnetic superlattice is studied by using the linear spin-wave approach and Green＇s function technique. It is found that four energy gaps and corresponding four frequencie in middle of energy gaps exist in the magnon band along Kx direction perpendicular to the superlattice plane. The spin quantum numbers and the interlayer exchange couplings all affect the four frequencies in middle of the energy gaps. When all interlayer exchange couplings are same, the effect of spin quantum numbers on the frequency wg1 in middle of the energy gap Δw12 is complicated, and the frequency wg1 depends on the match of spin quantum numbers in each layer. Meanwhile, the frequencies wg2, wg3, and wg4 in middle of other energy gaps increase monotonously with increasing spin quantum numbers. When the spin quantum numbers in each layer are same, the frequencies wg1, wg2, wg3, and wg4 all increase monotonously with increasing interlayer exchange couplings.     

Frequency in Middle of Magnon Band Gap in a Layered Ferromagnetic Superlattice

The frequency in middle of magnon energy band in a five-layer ferromagnetic superlattice is studied by using the linear spin-wave approach and Green's function technique. It is found that four energy gaps and corresponding four frequencie in middle of energy gaps exist in the magnon band along K_x direction perpendicular to the superlattice plane. The spin quantum numbersand the interlayer exchange couplings all affect the four frequencies in middle of the energy gaps. When all interlayer exchange couplings are same, the effect of spin quantum numbers on the frequency ω_g1 in middle of the energy gap Δω₁₂ is complicated, and the frequency ω_g1 depends on the match of spin quantum numbers in each layer. Meanwhile, the frequencies ω_g2, ω_g3, and ω_g4 in middle of other energy gaps increase monotonously with increasing spin quantum numbers. When the spin quantum numbersin each layer are same, the frequencies ω_g1, ω_g2, ω_g3, and ω_g4 all increasemonotonously with increasing interlayer exchange couplings.     

Acousto-optic Modulators with a Broadened Frequency Band for Fiber-Optic Lines

Technical Physics - The modulator/frequency shifter with single-mode fiber-optic waveguides for a radiation wavelength of 1064 nm has been designed and fabricated. A light beam was focused in the...     

Magnetoplasma oscillations of a two-dimensional electron layer in a bounded system

The spectrum of magnetoplasma oscillations of a two-dimensional electron layer in a transversal magnetic field is studied under the condition that the electron system is unbounded along the layer plane and screened in the perpendicular direction. It is shown that under certain conditions oscillation frequencies much lower than the electron cyclotron frequency exist. Also the electromagnetic wave-guided oscillations in the system are described. It is shown that a strong magnetic field causes a frequency shift and splitting, depending inversely on the external magnetic field and the transversal specific dimension.     

Temperature Effects on the Beat Heating of a Collisional Magnetoplasma

The beat heating of a magneto-plasma by two antiparallel electromagnetic waves at different temperatures is examined. The effects of plasma temperature, plasma electron collisions, plasma ion collisions and magnitude and direction of the magnetic field on the excitation of plasma electron waves and plasma ion waves are studied. A formula for the power absorption density of the plasma by using Maxwell's equations in conjuction with continuity and momentum equation. including collisions and pressure tensor terms, is derived. The contribution of the plasma temperature to the power absorption density, both at low and high beat frequencies, of the collisional and the non-collisional magnetised plasmas is found very significant and is illustrated numerically. The inclusion of pressure tensor term in the momentum equation is also found to cause characteristic changes in the power absorption density of the plasma with the orientation of magnetic field.     

FDTD Simulation for the Focusing Property of Extended Hemispherical Lens as Receiving Antenna

The focusing property of extended hemispherical lens, on which a linearly polarized plane wave is incident normally, is simulated by FDTD method. The focusing process is presented pictorially at different moment. Focal length is obtained and compared with that computed by other method. Good agreement has been found. The coupling between the focused incident wave and a waveguide in the focal plane of the lens is also simulated. The lens is used as antenna at millimeter wavelengths.