激光等离子体共振吸收中等离子体波对电子的加速

用二维多时标全电磁模相对论粒子模拟程序，对共振吸收中等离子何不皮的激发，电子的加速以及超热电子的产生进行了模拟计算，给出了合理的物理图像。     

强激光在磁化等离子体中的调制不稳定性

采用洛伦兹变换推导出左旋椭圆偏振强激光在磁化等离子体中的非线性色散关系,根据Karpman方法推导出激光场包络的非线性控制方程,分析了在磁化等离子体中左旋椭圆偏振激光的调制不稳定性,得到了调制不稳定的时间增长率。分析结果表明,磁化等离子体中自调制不稳定的极大增长率较非磁化情况明显减小,且在激光等离子体临界面附近处调制不稳定性的时间增长率显著增大。     

右旋偏振波对高密度等离子体的穿透实验

本文分析了右旋偏振波穿透高密度等离子体的条件,给出了理论根据及原理性实验的结果。实验证实,当ω_(ce)≈2ω时,右旋偏振波(哨波模)可以穿透很高密度的等离子体(ω_(pe)~2>>ω~2),并可能成为克服“再入”时“黑障”的一个途径。     

磁化等离子体中静电波的非线性发展和局域结构的形成

从Ｈａｓｅｇａｗａ-Ｍｉｍａ方程出发，对非线性漂移波进行解析和数值研究．数值结果表明，等离子体中静电波的初始扰动，由于非线性模耦合而发生演化，形成链状局域结构，并通过相互吞并，最后演化为稳定的涡旋 关键词：     

磁化碰撞等离子体对雷达波的共振吸收

使用平板几何对雷达工作频段的电磁波在磁化碰撞等离子体中的传播作了数值计算,计算结果表明,在均匀等离子体中,当等离子体碰撞频率f∞=0.1,0.5,1GHz及电磁波频率接近高混杂频率时,电磁波衰减和被吸收功率出现最大峰值,即出现共振吸收;当fen=1,10GHz时,电磁波衰减、被吸收功率和透射功率曲线变得很平坦;衰减和吸收功率随等离子体密度的增大而增大,在n=10^11cm^-3时,衰减可达100dB,吸收比可达80％。在非均匀等离子体中,电磁波的反射功率峰值比在均匀等离子体中大。因此,磁化均匀等郭了体更有利于等离子体隐身。     

磁化等离子体中静电漂移波和剪切阿耳芬波的非线性耦合

本文采用Hasegawa-Wakatani方程组研究磁化等离子体中静电漂移波和剪切阿耳芬波的非线性耦合。求得非线性方程组的偶极涡旋解。这些解属于本性电磁涡旋,对应的扰动磁场和纵向电流在涡旋边界上是连续的。 关键词：     

大气非均匀量子等离子体孤波解

本文探讨在大气环境下具有温度和密度梯度的非均匀量子等离子体系统,研究了该系统在离子与中子碰撞频率较低情况下的二维非线性流体动力学扰动方程．求得了在致密天体物理环境中静电势的近似解．     

激光等离子体波电子加速器

本文分别用理论分析和粒子模拟方法讨论了等离子体尾波加速器和拍波加速器的物理机制。结果表明,只要激光等离子体波足够强,加上适当强度的横向磁场,就可以把MeV数量级的电子在公尺距离内加速到GeV数量级的能量。另外,还用粒子模拟方法,研究了激光对热等离子体受激向后喇曼散射产生低相速度的等离子体静电波对低能电子加速的问题,探讨了多级或多波加速的可能性。结果表明,利用激光等离子体波加速器,在一般的实验室条件下,就可获得GeV数量级的高能电子。 关键词：     

一类量子等离子体类孤波的近似解析解

本文探讨了在一类量子等离子体系统,研究了该系统的非线性动力学扰动方程.利用改进的广义泛函变分迭代方法,求得了对应系统的类孤波近似解析解.     

Rb87基态超精细塞曼能级跃迁的偏振激发特性

本论述了Rb^87基态超精细塞曼能级光泵磁共振的偏振激发特性,给出了塞曼能级跃迁谱线随抽运光偏振特性的变化。     

可见光条纹相机可靠性实验研究

基于晨光号X光机开展了可见光条纹相机在复杂的辐射/电磁环境中的可靠性实验研究。利用序列脉冲激光的成像状态表征条纹相机的扫描状态,采取了不同的辐射/电磁防护措施,研究其对扫描状态的影响。实验研究获得了该类相机在此类复杂环境中正常工作的防护方法,主要包括增强辐射屏蔽使条纹相机附近的单发次等效空气吸收剂量不超过6μGy、减少相机机壳的缝隙、采取光电隔离的触发方式等。     

ǿ�����ڴŻ����������еĵ��Ʋ��ȶ���

采用洛伦兹变换推导出左旋椭圆偏振强激光在磁化等离子体中的非线性色散关系,根据Karpman方法推导出激光场包络的非线性控制方程,分析了在磁化等离子体中左旋椭圆偏振激光的调制不稳定性,得到了调制不稳定的时间增长率。分析结果表明,磁化等离子体中自调制不稳定的极大增长率较非磁化情况明显减小,且在激光等离子体临界面附近处调制不稳定性的时间增长率显著增大。     

Modulation instability by intense laser beam in magnetized plasma

Modulation instability of an intense right-hand elliptically polarized laser beam propagating through magnetized plasma is investigated by a new method. The nonlinear dispersion relation, in which the relativistic and ponderomotive nonlinearities are taken into account, is obtained for the laser radiation in magnetized plasma by the Lorentz transformation. The Karpman equation is firstly generalized to the case of three dimensions with three field components. When the nonlinear frequency shift of the electromagnetic field in plasma is involved, the nonlinear evolution equation for the slowly varying envelope of the laser field is obtained. Thus, modulation instability of the intense laser beam in magnetized plasma is studied and the temporal growth rate of the instability is derived. The analysis shows that the peak growth rate of self-modulation instability is increased due to the axial magnetization of plasma. It is also shown that the growth rate of modulation instability is increased significantly near the critical surface in a laser-plasma.     

线偏振激光在磁化等离子体中的调制不稳定性

 采用洛伦兹变换推导了线性偏振激光在磁化等离子体中的非线性色散关系,根据Karpman方法推导出横波的非线性控制方程,利用线性偏振激光在磁化等离子体中的非线性色散关系和非线性控制性方程,分析了在磁化等离子体中有限振幅的扰动引起的调制不稳定性,得到了线性偏振激光的调制不稳定的时间增长率与扰动波数之间的函数关系。分析结果表明：激光等离子体的临界面附近的磁调制不稳定性的时间增长率显著增大。     

偏振态对激光相干合成的影响

为了研究光束相干合成中偏振态的特性,取理想矩形光束进行模拟分析。通过改变偏振态的退偏率、偏振态夹角、参与合成的子束数目等,观察光场在远场叠加的合成效果。讨论了这些因素对远场合成效果的光强分布、峰值功率密度、光束质量因子等的影响。模拟结果显示：当退偏率小于10%、偏振态夹角小于18时,合成后光束质量因子小于1.1。     

偏振态对激光相干合成的影响

为了研究光束相干合成中偏振态的特性,取理想矩形光束进行模拟分析。通过改变偏振态的退偏率、偏振态夹角、参与合成的子束数目等,观察光场在远场叠加的合成效果。讨论了这些因素对远场合成效果的光强分布、峰值功率密度、光束质量因子等的影响。模拟结果显示:当退偏率小于10%、偏振态夹角小于18时,合成后光束质量因子小于1.1。     

Stimulated Raman backward scattering of a laser beam in a magnetized plasma

Stimulated Raman scattering of a laser beam is investigated in the plasma with strong self generated magnetic field. The magnetized plasma supports various localized radial and azimuthal modes of lower hybrid frequencies. The density fluctuations due to lower hybrid modes couple with the oscillating velocity due to the pump, and drive the scattered wave. Equations describing the Raman process are derived and effects of various modes are studied on the growth rate analytically. Self generated magnetic field has a strong localization effect on the Raman process and growth rate is maximum for radial eigen mode number q = 0 and azimuthal eigen mode number l = 3. The frequency shift has signatures of self generated magnetic field and could serve as a diagnostic.     

Photon polarization tensor in a magnetized plasma system

We investigate the photon polarization tensor at finite temperatures in the presence of a static and homogeneous external magnetic field. In our scheme, the summing of the Matsubara frequency is performed after Poisson resummation, which is easily completed and converges quickly. Moreover, the behaviors of finite Landau levels are presented explicitly. It shows a convergence while summing infinite Landau levels. Consequently, there is no necessity to truncate the Landau level in a numerical estimation. At zero temperature, the lowest Landau level (LLL) approximation is analytically satisfied for the vacuum photon polarization tensor. However, we examine that the LLL approximation is not enough for the thermal polarization tensor. The thermal tensor obtains non-trivial contributions from the finite-n Landau levels. And, photon spectra gains a large imaginary contribution in thermal medium, which is the so-called Landau damping. Finally, it is argued that the summation of Matsubara frequency is not commuted with Landau level ones, such conjecture is excluded in our calculations.     

Second-harmonic generation of a Gaussian laser beam in a self created magnetized plasma channel

The second-harmonic generation of an intense self-guided right circularly polarized laser beam in a magnetized plasma is investigated. The laser imparts oscillatory velocity to electrons and exerts a radial ponderomotive force on them to create a depleted density channel. The critical power for self-focusing shows huge reduction as electron cyclotron frequency approaches the laser frequency (/spl omega//sub c/ /spl rarr/ /spl omega/). In the presence of the self-created radial density gradient, the laser drives a density perturbation at the fundamental frequency. The density perturbation beats with the oscillatory velocity to produce a second harmonic current density, driving second harmonic radiation copropagating with the laser. The second harmonic, however, is azimuthally asymmetric with /spl theta/-variation as exp(i/spl theta/). Its amplitude shows resonant enhancement as /spl omega//sub c/ /spl rarr/ /spl omega/.