超短超强激光-等离子体中自生磁场的研究

本文回顾了激光-等离子体相互作用中自生磁场的产生以及提出的各种产生机制和诊断方法；比较全面地介绍了超短超强激光与等离子体相互作用中产生自生磁场的理论、数字模拟以及实验研究的状况；重点阐述了超短超强激光-等离子体相互作用中自生磁场对谐波发射影响的理论以及根据该理论完成的实验测定。     

超短超强激光与稀薄等离子体相互作用中后孤立子的观测

开展了超短超强激光与稀薄等离子体相互作用实验,在实验中采用等离子体单色成像法观测等离子体发光图像,捕捉到了近乎对称的环形等离子体发光结构. 在对实验结果进行分析并与理论预言进行比较后确认这是由激光-等离子体相互作用形成的后孤立子云外围的高密度等离子体壳层发光所致. 同时通过对等离子体通道的观测还发现,孤立子的形成对超短超强激光在稀薄等离子体中的传输产生了非常大的影响. 关键词： 超短超强激光 稀薄等离子体 单色成像 后孤立子     

飞秒激光与等离子体相互作用中自生磁场的测量

自J．A．Stamper首先对自生磁场进行实验研究以来，人们的探索表明超强激光与固体靶相互作用中，在过密和次密等离子体区产生可能高达10^4T的自生磁场。     

激光等离子体相互作用中Weibel不稳定性

利用粒子模拟法对超强激光与等离子体相互作用中产生的Weibel不稳定性及其产生机制进行了详细的研究。给出不稳定性的线性色散关系和饱和磁场与各向异性参数之间的函数关系,发现Weibel不稳定性的存在使超强激光在等离子体中激发的自生磁场饱和,饱和自生磁场的存在使粒子速度分布在激光传播方向上表现出各向异性。讨论了Weibel不稳定性的线性和非线性饱和过程,对更好地理解快点火物理中自生磁场的产生、快电子输运等过程有重要意义。     

等离子体通道中的自生磁场

研究了超短脉冲强激光在等离子体通道中传播时产生的自生磁场．利用相对论动量方程和泊松方程及安培定律得出自生磁场的一个基本公式，在此基础上解析并数值研究了通道中产生的自生磁场的特性和结构，初步探讨了超短脉冲强激光在等离子体中传播时形成的排空效应对自生磁场的影响，并分析了产生自生磁场的机制 关键词：     

激光聚变快点火机理研究

对超强超短激光等离子体相互作用和快点火机理及其物理可行性进行了理论和数值模拟研究.研制了二维和二维半粒子云模拟程序,数值模拟了超强超短激光脉冲在非均匀等离子体中的传播.提出快点火穿孔速度和深度以及用于快点火的超强超短激光器的初步指标 关键词： 超强超短激光等离子体相互作用 快点火机理 粒子云模拟     

激光入射角对靶面方向超热电子发射的影响

实验研究了超短超强激光脉冲与薄膜靶相互作用中产生的超热电子角分布随激光入射角的变化.在靶面方向观测到一束方向性很好的高能超热电子.该高能超热电子束的电子数目随着激光入射角的增大而增大.对结果的分析表明，表面准静态磁场是导致表面电子产生的主要原因. 关键词： 超热电子 表面准静态磁场 超强激光脉冲与等离子体相互作用     

利用高次谐波诊断自生磁场

实验在100TW超短超强激光装置上进行。采用OMA谱仪加CCD测量系统，测量2ωo和3ωo谐波谱的精细结构，回推出激光与等离子体相互作用中产生的自生磁场大小，验证通过谐波谱的精细结构推断白生磁场方法的可靠性。     

超强激光场物理学

首先,评述了超强激光场的理论结果;其次,描述了超短光脉冲在密的气体和光学介质传播中的自作用;第三,评述了强场离化无碰撞等离子体中高度离化的离子产生,及高功率超短激光脉冲巨大强度的电场可用于电子加速;第四,分析了超短声脉冲和无线电脉冲的产生和应用,讨论了在不同条件下,激光辐射谐波和 Ｘ 射线激光的产生,进一步评述了超强激光脉冲与凝聚靶相互作用可以产生接近星体物质参数的高温、超密、强磁场和巨大压力等离子体;最后,简要叙述了激光激发核、核反应,高能电子─光子相互作用的可能效应及可能进行的实验。     

超强激光场物理学

首先,评述了超强激光场的理论结果;其次,描述了超短光脉冲在密的气体和光学介质传播中的自作用;第三,评述了强场离化无碰撞等离子体中高度离化的离子产生,及高功率超短激光脉冲巨大强度的电场可用于电子加速;第四,分析了超短声脉冲和无线电脉冲的产生和应用,讨论了在不同条件下,激光辐射谐波和 Ｘ 射线激光的产生,进一步评述了超强激光脉冲与凝聚靶相互作用可以产生接近星体物质参数的高温、超密、强磁场和巨大压力等离子体;最后,简要叙述了激光激发核、核反应,高能电子─光子相互作用的可能效应及可能进行的实验。     

The kinetic theory of magnetic-field generation in a Langmuir plasma

We develop a two-timescale kinetic theory for the nonlinear generation process for a slow-timescale magnetic field in a hot collisionless Langmuir plasma. We show that the basic damping of this magnetic field is due to the collisionless skin effect.     

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.     

会切磁场中大回旋电子束产生的研究

研究了会切磁场产生的机理。通过对Moster-Molnar 模型的探讨, 建立了会切磁场的物理模型。在会切磁场理论分析和数值模拟基础上, 探讨了影响会切磁场设计的因数; 利用拉格朗日公式求解了会切磁场中电子运动轨迹。探讨了会切磁场与大回旋空心会切电子枪的关系, 得到了改进会切电子枪性能的一些一般性结论。     

Theory of magnetic shape memory effect and pseudoelastic deformation in Ni-Mn-Ga alloys

The effect of the magnetic field on the deformation behavior of magnetic alloys of the Heusler type under different loading conditions is discussed in terms of the theory of diffuse martensitic transitions. The effects of magnetic shape memory, pseudoelastic deformation, and generation of reactive stresses in response to the magnetic field are considered. The theoretical relationships are compared with the experimental data available in the literature.

     

Roles of electric field on toroidal magnetic confinement

Theoretical research on the influence of electric field on toroidal magnetic confinement is surveyed. The static electric field is first described. A physical picture of the radial electric field generation and its influence on confinement are shown. Neoclassical effects as well as the non-classical processes are discussed. Emphasis is made on the connection with improved confinement. Convective cells with a nonuniform potential on the magnetic surface are also discussed. The roles of the fluctuating electric field are then reviewed. Recent progress in anomalous transport theory is addressed. Through these surveys, the impact of experiments using the heavy ion beam probes on modern plasma physics is illustrated     

Magnetic reconnection in toroidal eta(i) mode turbulence

Based on three-dimensional simulations of the Braginskii equations we show that for typical plasma-edge parameters the saturation of electromagnetic toroidal eta(i) mode turbulence is controlled by the self-generation and subsequent annihilation of radial magnetic field perturbations. This should be contrasted with the electrostatic limit, where the growth of the linear eta(i) mode is terminated by the onset of sheared flow modes driven by the radial plasma streams. The impact of the saturation amplitude on the transport level is substantial and is not in accord with simple mixing length arguments, suggesting that electromagnetic effects should generally be included in simulations of eta(i) mode turbulence.     

Experimental evidence of a zonal magnetic field in a toroidal plasma

A zonal magnetic field is found in a toroidal plasma. The magnetic field has a symmetric bandlike structure, which is uniform in the toroidal and poloidal directions and varies radially with a finite wavelength of mesoscale, which is analogous to zonal flows. A time-dependent bicoherence analysis reveals that the magnetic field should be generated by the background plasma turbulence. The discovery is classified as a new kind of phenomenon of structured magnetic field generation, giving insight into phenomena such as dipole field generation in rotational planets.     

Theory of electromagnetic generation of acoustic waves in metals

The theory of the anomalous skin effect in metals is used in order to study the direct generation of ultrasound by electromagnetic radiation incident on a metal surface, in the absence and in the presence of a magnetic field. The non-monotonic behaviour of the acoustic flux observed experimentally, as a function of the magnetic field can be explained within the framework of the free-electron model assuming that the electrons are scattered diffusely from the metal surface. The reason for this behaviour is traced to the variation of the relative phases of the collision drag force on the bulk ions and that on the surface with increasing magnetic field. The relations between existing theories of direct generation of ultrasound have been investigated within both the free-electron approximation and the effective-mass theory. We conclude that, besides the collision drag force, the Lorentz force and the Bragg reaction force, an additional ‘deformation’ force acts upon the positive ions. We find that the assumption of electron diffuse surface scattering is the only mechanism that can account for the observations on the variety of materials investigated. We also analyse, within a simple effective-mass approximation, possible band structure effects on acoustic wave propagation in metals and on the helicon-phonon interaction.     

Renormalized theory of magnetic field generation in resonance absorption

DC magnetic field generation in resonance absorption is studied, in a non-linear regime, when it becomes of sufficient order of magnitude to affect wave propagation, as well as electron-ion collisions or thermal dispersion do. It is shown that a simple expression obtained in the linear regime is still valid in the non-linear theory. Scaling laws are set up.