Tokamak中磁力线的随机特性

在直柱近似下，运用哈密顿非线性振荡系统理论研究了平衡态磁场在磁扰动下进入随机状态的过程．结果表明：一阶扰动哈密顿量仅与径向扰动磁场有关；在单模扰动下，磁力线呈规则磁岛结构；在双模扰动下，给出了磁力线进入随机态的重叠判据；在特定多模优动下，将Ｐｏｉｎｃａｒé截面上点演化关系化为一类标准映象。 关键词：     

磁场旋度对磁场漂移的影响

讨论了静态非均匀磁场中的磁场旋度对带电粒子引导中心漂移的影响。运用三维矢量分析的方法,将带电粒子垂直于磁场运动所引起的磁场漂移分为两项,分别由磁场的曲率和磁场的旋度决定。给出了螺旋状环形磁场中由磁场旋度引起的磁场漂移的近似表达式,讨论了该漂移成分对于该磁场中通行粒子轨道和捕获粒子轨道的可能影响。结果表明,带电粒子垂直于磁场运动所引起的磁场漂移主要由磁场的曲率决定,而磁场旋度对该漂移的影响比较微弱。     

�ų����ȶԴų�Ư�Ƶ�Ӱ��

讨论了静态非均匀磁场中的磁场旋度对带电粒子引导中心漂移的影响。运用三维矢量分析的方法,将带电粒子垂直于磁场运动所引起的磁场漂移分为两项,分别由磁场的曲率和磁场的旋度决定。给出了螺旋状环形磁场中由磁场旋度引起的磁场漂移的近似表达式,讨论了该漂移成分对于该磁场中通行粒子轨道和捕获粒子轨道的可能影响。结果表明,带电粒子垂直于磁场运动所引起的磁场漂移主要由磁场的曲率决定,而磁场旋度对该漂移的影响比较微弱。     

参考粒子在α磁铁中的运动

给出参考粒子对α磁铁入出射角的理论计算, 以及参考粒子在均匀梯度磁场内运动轨迹的解析解, 从物理上解释了α磁铁的消色散原理.     

海森伯XXZ模型中量子相干性的研究

研究了非均匀磁场和均匀磁场作用下的两量子位海森伯XXZ模型中的量子相干性,详细分析了各个参数对量子相干性的影响.研究发现,量子相干性随非均匀磁场的变化会因为均匀磁场的加入而变得平缓.不同的各项异性参数和磁场条件下,量子相干性随温度的变化有很大的差异.和纠缠相比,量子相干性随非均匀磁场只表现为单峰现象.此外,通过对不同初始态下量子相干性的动力学演化行为进行研究,给出了非均匀磁场对演化过程的影响.论文的研究结果对于认识量子相干性问题具有一定的意义.     

多粒子W态的绝热制备

通过利用时间依赖的外磁场,提出了绝热制备多粒子W态的新方法.同时给出了驱动n个自旋1/2粒子从未纠缠态到W态的相互作用哈密顿量以及绝热和非绝热演化条件,展示了能量和靶态布据随时间的演化图.     

带电粒子在磁镜中的重力漂移运动模拟研究

基于电磁学基本原理讨论了由两个相互平行的载流圆环构造的简单磁镜场的场分布以及均匀磁场中粒子运动的磁通量守恒量关系式.通过理论分析和数值模拟研究了在弱非均匀磁镜场中带电粒子的重力漂移运动,并运用重力漂移速度公式验证模拟结果,二者符合得较好,结果表明弱磁场下带电粒子所受重力会破坏带电粒子在磁镜场中运动的磁通量守恒关系.     

耦合压缩Landau态

引入Landau体系（带电粒子在垂直于均匀磁场平面内的运动）的耦合压缩态．这类耦合压缩态所给出的关于带电粒子圆周运动的信息与非耦合压缩Landau态所给出的信息存在很大的差异． 关键词：     

均匀磁场中带电粒子的非定态波函数

取圆心坐标算符和初始机械动量算符为力学量完全集，给出均匀磁场中带电粒子的非定态波函数．     

磁场对荷电粒子电荷态的分析作用

对磁场中荷电粒子磁刚度与粒子能量和电荷态的关系作了深入讨论,给出了一个选择不同电荷态粒子的磁铁电流关系式。     

Stochastic behaviour in presence of an electrostatic wave due to the crossing of multiple cyclotron resonances in an inhomogeneous magnetic field

The criterion for the occurence of stochastic behaviour of particle trajectories in the field of an electrostatic wave is obtained taking into account the longitudinal inhomogeneity of the ambient magnetic field. The origin of the stochasticity is explained. The optimum conditions for particle heating are obtained at a wave amplitude below the threshold of stochasticity in a homogeneous plasma.     

Kinetic Description of Particle Interaction with a Gravitational Wave

The interaction of charged particles, moving in a uniform magnetic field, with a plane polarized gravitational wave is considered using the Fokker-Planck-Kolmogorov (FPK) approach. By using a stochasticity criterion, we determine the exact locations in phase space, where resonance overlapping occurs. We investigate the diffusion of orbits around each primary resonance of order m by deriving general analytical expressions for an effective diffusion coefficient. A solution of the corresponding diffusion equation (Fokker-Planck equation) for the static case is found. Numerical integration of the full equations of motion and subsequent calculation of the diffusion coefficient verifies the analytical results.     

Fine Structure of the Local Alfven Resonances in Cold Plasma Placed in Bumpy Magnetic Field

Unlike in the case of an axial magnetic field, in which each mode of electromagnetic wave excited by an external source propagates independently, ripples in a bumpy magnetic field cause the wave to propagate as a wave envelope that contains also satellite harmonics in addition to the main harmonic. The influence of this multimodity on the distribution of electromagnetic waves within the local Alfven resonance regions is studied and compared for the following three cases. In the first case, Alfven resonance takes place for a main harmonic of the wave. In the second case, Alfven resonance occurs in the same region for two main harmonics which are coupled due to the plasma periodic axial inhomogeneity. Alfven resonance for a satellite harmonic is considered in the third case.     

Laboratory modeling of physical processes in the ionosphere modified by powerful radio emission

We present the results of the laboratory modeling of physical processes occurring in the ionosphere during active experiments on the ionospheric modificaton by powerful radio emission. The process of nonuniform thermo-diffusion of a magnetoplasma due to local electron heating is studied under the conditions modeling the ionospheric F layer. It is revealed by direct measurements that thermo-diffusion and diffusion are accompanied by excitation of macroscopic eddy currents. In this case, electrons and ions diffuse along and across the magnetic field, respectively, and the eddy current is carried by particles of the background plasma. As a result, a magnetic-field-aligned density depletion rapidly forms in the plasma. The possibility of trapping and guided propagation of Langmuir waves in such a plasma inhomogeneity is demonstrated. Conditions are found under which the wave trapping and the formation of the inhomogeneity occur in a self-consistent regime, i.e., Langmuir waves are trapped in a small-scale inhomogeneity which, in turn, is formed due to local plasma heating by the field of the trapped waves. Such nonlinear wave trapping takes place only above a certain threshold, which significantly increases in the vicinity of gyroharmonics. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 8, pp. 731–746, August 2007.     

Chaotic dynamics of charged particles in the field of two monochromatic waves in a magnetized plasma

We study the dynamics of charged particles in the presence of two electrostatic waves propagating obliquely to an ambient magnetic field. The presence of a second wave makes the problem a two-dimensional and time-dependent one with a complicated phase space behavior. We derive a set of difference equations (maps) for the nonrelativistic particle motion limit and numerically study them to elucidate the various aspects of the phase space dynamics. For the general case of oblique propagation, we observe synergistic effects leading to the lowering of the stochasticity threshold and the concomitant reduction in electric field amplitudes for particle heating applications. These results can be understood in terms of the resonance structures associated with the two waves and we obtain approximate analytic expressions for the thresholds. For the degenerate case of omega(1)=nOmega,omega(2)=mOmega (where omega(1),omega(2) are the frequencies of the two waves, Omega is the cyclotron frequency and n,m are integers) and strictly perpendicular propagation, the problem simplifies to a one-and-one-half-dimensional one. We observe the presence of stochastic webs in this situation. (c) 1996 American Institute of Physics.     

Scattering of a Rayleigh surface acoustic wave by a small-size inhomogeneity in a solid half-space

We use the Born approximation of the perturbation method to solve the problem of scattering of a harmonic Rayleigh surface acoustic wave by a weak-contrast inhomogeneity that is small compared with the wavelength and is located in a solid half-space near its boundary. The material of the inhomogeneity differs from the material of the half-space only in its density. The Rayleigh wave incident on the inhomogeneity is excited by a monochromatic surface force source acting normally to the half-space boundary. We derive expressions for the displacement fields in the scattered spherical compressional and shear (SV- and SH-polarized) waves. Scattering of the Rayleigh wave into a Rayleigh wave is studied in detail. We find expressions for the vertical and horizontal components of the displacement vector in the scattered Rayleigh wave as well as its radiated power. It is shown that the field of the scattered surface wave is mainly formed by vertical oscillations of the inhomogeneity in the field of the incident wave. In this case, the radiated power for the scattered Rayleigh wave formed by vertical motion of the inhomogeneity in the incident-wave field depends on the depth of the inhomogeneity as the fourth power of the function describing the well-known depth dependence of the vertical displacements in the Rayleigh surface wave. Correspondingly, the dependence of the radiated power for the scattered Rayleigh wave formed by horizontal motion of the inhomogeneity depends on its location depth as the fourth power of the depth dependence of the horizontal displacements in the Rayleigh surface wave. We perform calculations of the ratio between the powers of the scattered and incident Rayleigh waves for different ratios between the velocities of the compressional and shear waves in a solid. It is shown that the radiated power for the scattered surface wave decreases sharply with increasing depth of the subsurface-inhomogeneity location. Thus, the scattering of a Rayleigh wave into a Rayleigh wave is fairly efficient only when the location depth of the inhomogeneity does not exceed about one-third of the wavelength of the shear wave in an elastic medium.     

Ion drag forces and magnetomechanical effect

Ion flows (ion drag forces) acting on macroscopic-size particles play a significant role in a plasma containing macroparticles. It is shown that ion drag forces can explain the magnetomechanical effect. The formula is derived for determining the dependence of the moment of the magnetomechanical effect on the type and pressure of the gas, tube radius, current, and magnetic field. This formula is in satisfactory agreement with experimental data for discharges in argon and neon with a relatively low magnetization of electron motion. For a high magnetization, the measured values of the moment of the magnetomechanical effect exceed the calculated values, which can be due to the effect of magnetic field nonuniformity and inhomogeneity of the plasma near the solenoid ends.     

Transformation of waves and eigenoscillations of an inhomogeneous layer of hot plasma

On the case of a plasma layer we show that in a hot plasma with the inhomogeneity of density across the magnetic field there exist eigenmodes for frequencies of hybrid resonance that are combinations of two kinds of waves: The potential long waves of cold plasma and the short-wave Bernstein modes. Their coupling is due to transformation in the region of the hybrid resonance. These eigenmodes can also be travelling waves with energy transmitted in one direction by a long wave and in the opposite one by a short wave. Different types of eigenmodes and corresponding quantization conditions are obtained.     

Magnetostatic surface waves produced by an inhomogeneity of the anisotropy with a turning point of the spectral function on a ferromagnet surface

Magnetostatic surface waves with fixed frequency and wave vector are predicted to exist in a ferromagnet with an inhomogeneity of the magnetic anisotropy such that the spectral function has a turning point on the surface. This result is most important for the case when an external magnetic field magnetizes the ferromagnet perpendicular to its surface. The frequency of the surface wave is determined by the frequency of the magnetostatic volume wave at the surface of the ferromagnet, and the wave vector is determined by the surface values of the local magnetic anisotropy field and its derivative. Zh. Tekh. Fiz. 68, 118–123 (June 1998)     

驻波驱动的等离子体电子相对论随机加速

就电子在等离子体中被驻波随机加速的可能性和条件进行了分析和数值计算.分析结果表明:等离子体中的电子在驻波场中的两个共振区的叠加导致电子的随机行为的产生.并估算了随机加速的阈值.数值计算了电子的随机加速的能量和随机加速的阈值.采用Poincare截面图技术,跟踪了电子的随机运动的轨迹. 关键词：