Retrapping of current in a vacuum transmission line upon reflection of a magnetic self-insulation wave from a load

The equations derived in the framework of the Brillouin model of an electron layer in a “hot” vacuum transmission line form the basis for analysis of reflection of an electromagnetic wave from a load, leading to a redistribution of currents in the magnetically insulated transmission line (MITL). It is shown theoretically for the first time that conversion (retrapping) of a considerable fraction of the current in the electron layer to the cathode current upon the reflection of the wave from the load upon an insignificant change in the current and voltage in the line is possible even under the conditions close to the self-consistent regime. This effect can be explained by the change in the state of the electron layer under the action of the reflected wave, which is associated with a transition of the system from the right branch of the magnetic self-insulation curve to the left branch.     

Calculation of the properties of a self magnetic insulation wave in a vacuum transmission line on the basis of conservation laws

On the basis of the conservation laws for the energy and the z component of the momentum in a self magnetic insulation wave propagating in a vacuum transmission line, the relativistic factor γ_m corresponding to the voltage at the outer boundary of the electron sheath is found under the assumption that all electrons incident to the anode have identical energies and identical angles of incidence. The effect of energy losses in the precursor wave on basic properties of the self magnetic insulation wave is investigated.     

Influence of bias magnetic field on the vacuum arc in double‐break vacuum circuit breakers

When double‐break vacuum circuit breakers (VCBs) interrupt the fault current, the series arc will generate their individual magnetic fields in different breaks. The magnetic field in one break will influence the arc in another break if the magnetic field is strong enough or the two breaks are very close. In this case, an interactive magnetic field effect happens. This field is also called the bias magnetic field (BMF). BMF can cause anode erosion and affect the performance at current zero. The distribution of BMF and the optimal configuration of the double‐break VCBs were obtained by the electromagnetic field simulation using the Ansoft Maxwell software. Based on the simulated magnetic field data, in the experiments, the interaction between the series vacuum arcs in double‐break VCBs was equivalent to the interaction between a single vacuum arc and the magnetic field generated by a Helmholtz coil. A high‐speed CMOS camera was used to record the trajectory of the vacuum arc plasma under different BMFs with different types of contacts. The results show the BMF can increase the arc voltage, and the arc becomes unstable. When the BMF becomes stronger, the arc voltage increases, and the arc becomes more unstable. In addition, for different types of contacts, the development process of the arc and the influence level are different under the same BMF. For a Wan‐type transverse magnetic field (TMF) contact or strong BMF, metal sputtering is evident and anode erosion becomes serious. For a cup‐type axial magnetic field (AMF) contact, the influence of BMF on the series arc plasma in double‐break VCBs is less than that of the Wan‐type TMF contact. The results of this work may be helpful for the design of compact double‐break VCBs.     

Spin wave mode excited by spin-polarized current in a magnetic nanocontact is a standing self-localized wave bullet

We demonstrate that the lowest threshold of spin-wave excitation in an in-plane magnetized magnetic nanocontact driven by spin-polarized current is achieved for a nonlinear self-localized spin-wave mode-standing spin-wave bullet--stabilized by current-induced nonlinear dissipation. This nonlinear mode has a nonpropagating evanescent character, is localized in the region comparable with the contact radius, and has a frequency that is lower than the frequency of the linear ferromagnetic resonance. The threshold current and generated frequency at the threshold theoretically calculated for this mode are in quantitative agreement with experiment.     

Characteristics of electron beams formed in a diode with magnetic insulation

The problems of the formation of relativistic electron beams in a cylindrical diode with an annular cathode are discussed in the approximation of an infinitely strong guiding magnetic field. The beams are treated as infinitely thin. The following cases are investigated: 1) The formation of an electron beam moving off the cathode with an initial velocity. The case in which the field on the cathode is not equal to zero is investigated. It is shown that the potential of the electron beam can be determined in a nonunique fashion in the drift region. 2) The formation of a two-velocity electron beam. The possibility of controlling the flow of kinetic energy of the beam by varying the fraction of fast electrons in it is shown. 3) The formation of an electron beam in a diode with the help of two opposed cathodes at different potentials. A strong dependence of the current in the diode on the potential difference between the cathodes is obtained.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 36–39, December, 1981.     

Propagation of whistlers in a plasma with a magnetic field duct

The propagation of whistlers in a homogeneous magnetized plasma in the presence of a magnetic field duct has been experimentally investigated. The possibility of efficiently trapping whistlers in a narrow (wavelength-scale) cylindrical duct with the increased field has been demonstrated. It has been shown that a comparatively slight perturbation of the external magnetic field (δB/B₀ ～ 0.1) can significantly change the spatial structure and increase the amplitude of whistlers near the duct axis.     

Propagation of a solitary fission wave

Reaction-diffusion phenomena are encountered in an astonishing array of natural systems. Under the right conditions, self stabilizing reaction waves can arise that will propagate at constant velocity. Numerical studies have shown that fission waves of this type are also possible and that they exhibit soliton like properties. Here, we derive the conditions required for a solitary fission wave to propagate at constant velocity. The results place strict conditions on the shapes of the flux, diffusive, and reactive profiles that would be required for such a phenomenon to persist, and this condition would apply to other reaction diffusion phenomena as well. Numerical simulations are used to confirm the results and show that solitary fission waves fall into a bistable class of reaction diffusion phenomena.     

Propagation of light in a structure with a regular magnetic inhomogeneity

The reflection and transmission of a light wave normally incident on a layer with a regular magnetic inhomogeneity described by a harmonic function are investigated. Solutions to the Maxwell equations for such a medium and the Jones matrices determining the magneto-optical characteristics of the structure under consideration (the coefficients of transmission and reflection and the degrees of polarization of transmitted and reflected waves) are obtained.     

Influence of the vacuum magnetic moment on the induced radiation of an electron in a plane wave

Expressions are obtained for the probability and intensity of induced radiation from an electron with a vacuum magnetic moment moving in a plane electromagnetic wave of small amplitude. The wave is supposed to be monochromatic and to have random polarization. The results of previous publications on this subject [4–6] are included here as special cases.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 51–54, August, 1972.     

磁芯对螺旋线放电波过程的影响

提出了采用渐开线硅钢叠片的变压器磁芯与螺旋线的一体化的长脉冲产生结构;计算了螺旋线引入磁芯后,电磁波延迟传输的慢波系数和波阻抗参数,以及脉冲形成的输出参数,并开展了数值模拟进行验证。研究结果表明：引入磁芯后,螺旋线上慢波传输时,内外筒电流沿磁芯基底而非磁芯表面;磁芯的径向厚度相对磁芯径向尺寸越小,磁芯对脉冲形成的影响越小。     

Plasma expansion and current flow in a vacuum arc with a smallanode

A low-density plasma flow in a vacuum arc with a small anode, which intercepts only part of the cathodic plasma jet, was studied theoretically using a two-dimensional approximation. The plasma expansion was modeled using the sourceless steady-state hydrodynamic equations, where the free boundary of the plasma was determined by a self-consistent solution of the gasdynamic and electrical current equations. Magnetic forces from the azimuthal self-magnetic field were taken into account. The influence of the ratio of the anode radius to initial plasma jet radius on the plasma density, velocity, current distribution, and anode sheath potential drop is analyzed. It is shown that the mass and current flow in a 500 A arc are compressed near the axis. This leads to an increase in the plasma density by a factor of two and in the axial current density by a factor of 1.5     

内部真空度对真空绝热板导热系数的影响

真空绝热板板内真空度是影响真空绝热板绝热性能的关键因素之一,通过合理地降低板内真空度以降低板内残余气体引起的导热,继而以维持其较低的导热系数。在真空绝热板芯材内部埋置微型压力传感器,通过测量板内残余气体压力变化,检测真空绝热板内的真空度,并结合大平板导热仪,获取对应压力下的真空绝热板导热系数。通过实验和理论模型计算得到板内真空度与真空绝热板绝热性的关系,以及得到真空绝热板板内真空度与导热系数的最佳组合。     

Propagation of vacuum arc plasma beam in a toroidal filter

An analytical solution to the problem of plasma beam transport in a toroidal magnetic filter for unmagnetized ions is derived. A two-fluid model taking into account electromagnetic and pressure forces, electron-ion collisions, magnetic force line curvature, and radial dependence of centrifugal force is used. From comparison with experimental data it is shown that the obtained solution describes well the main properties of plasma beam behavior in the filter, e.g. (1) the relative value of the ion current along the torus decreases exponentially, (2) the deflection of the plasma beam from the center of the torus correlates with the centrifugal drift of the plasma beam across a magnetic field, and (3) experiment and theory agree well on the weak correlation between magnetic field strength and filter efficiency     

Motion and radiation of an electron exhibiting a vacuum magnetic moment in the field of a plane electromagnetic wave

A study is made of the motion of an electron exhibiting an anomalous magnetic moment and moving in the field of a plane circularly polarized electromagnetic wave. An exact solution is found to the generalized Dirac equation and is utilized to study the emission of electromagnetic radiation from the electron (the Compton effect). It is shown that allowance for the anomalous magnetic moment of the electron leads to: a frequency shift, a change in the total radiated power, polarization of the radiation, and to spin effects.     

Propagation of a monochromatic electromagnetic plane wave in a medium with nonsimple motion

An exact analytical solution is obtained for the trajectory of the wave vector of a monochromatic electromagnetic plane wave in a medium with nonsimple motion. It is shown that the spatial dragging of the electromagnetic wave by the moving medium can be described correctly in the general case only if relativistic terms of order β ² are taken into account. Zh. Tekh. Fiz. 69, 97–100 (May 1999)     

基于层状模型的功能梯度板中兰姆波传播研究

功能梯度板中的兰姆波的传播在实际工程中有着非常广泛的应用。采用层状模型研究了兰姆波在材料特性沿厚度方向连续变化的功能梯度板中的传播特性。通过数值计算获得了层状板中兰姆波的色散关系,并与已有结果进行了比较,获得了材料属性沿厚度方向呈指数变化和多项式变化时功能梯度板中兰姆波的波速和位移解。当材料属性连续变化时,兰姆波各阶模态的波速与位移都将发生变化。相比于兰姆波的高阶模态,低阶模态的波速变化更加明显。本文的研究可为功能梯度板的设计提供参考。     

Broadening of the spectral line of spin self-oscillations in a nanocolumn magnetic structure upon magnetic field and current variations

The spin dynamics in a thin layer of a nanocolumn layered magnetic structure during the flow of a spin-polarized current in the presence of magnetic fluctuations is theoretically analyzed. Using the macrospin model, the frequency and Q factor of the spin oscillations are calculated as functions of the spin-polarized current upon the occurrence of current self-generation.     

Propagation of electromagnetic waves in a medium with nonlinear magnetic susceptibility

The interaction of electromagnetic waves in a medium with nonlinear magnetic susceptibility is investigated. On the basis of Tinkham's measurements an antiferromagnet showing a resonance in the submillimeter region is considered as a nonlinear medium. The solution of both the Landau-Lifshitz and Maxwell equations leads to the RHS wave equation. Its solution with boundary conditions shows that the amplitude of the reflected wave from the nonlinear medium on a combined frequency can be non-zero.     

真空中A-B-A绝缘结构的电场分析

提出了一种变插入层电导率和介电常数的三层(A-B-A)绝缘结构。分析了插入层(A)电导率和介电常数对三层绝缘结构真空-绝缘子-阴极三结合点处和真空-插入层绝缘子(A)-主绝缘子(B)三结合点处电场的影响,结果发现通过控制插入层电导率和介电常数可以有效降低真空-绝缘子-阴极三结合点处的电场又不至于使真空-插入层绝缘子-主绝缘子三结合点处电场过高。考虑了介质表面带电的情况,分析插入层介质表面带不同极性电荷对真空-绝缘子-阴极和真空-插入层绝缘子-主绝缘子两个三结合点电场分布的影响。估计了三层绝缘结构真空沿面闪络电压的变化趋势,发现在插入层电导率或介电常数不断增大时,真空沿面闪络电压会呈现先上升后下降,最后趋于稳定。