部分离化激光等离子体的受激喇曼散射不稳定性

由于部分离化激光等离子体中存在束缚电子，它可显著改变其参量不稳定性。本文分析了部分离化激光等离子体的受激喇曼散射的非线性色散关系，计算了钕玻璃倍频和三倍频激光受激喇曼散射的增长率，结果表明，前向受激喇曼散射显著增强，后向受激喇曼散射影响不大。     

强激光部分离化等离子体受激喇曼散射

在强激光重元素靶等离子体中，电子是不能完全剥离的，带有未离化束缚电子的原子的形状受强激光或超强激光与它的相互作用要发生变化，从而产生极化电流，势必影响强激光等离子体相互作用，随着激光聚变发展的要求，精密物理的需要，研究束缚电子对受激喇曼散射的影响很有必要。     

强激光脉冲在部分离化等离子体中的传播特性

采用变分法给出了强激光脉冲在部分离化等离子体中传播的参数演化方程,其中考虑了相对论自聚焦、有质动力激发尾波场以及部分离化非线性极化强度的影响。通过非线性动力学分析的方法,得到了强激光脉冲以恒定焦斑半径传播时的激光、等离子体参数匹配条件。研究表明:在部分离化等离子体中,激光自聚焦随着电离程度的增大而增强;有质动力激发的尾波场进一步增强激光脉冲的自聚焦;相对于等离子体密度而言,激光强度对激光脉冲的自聚焦更有影响。     

强激光脉冲在部分离化等离子体中的传播特性

采用变分法给出了强激光脉冲在部分离化等离子体中传播的参数演化方程,其中考虑了相对论自聚焦、有质动力激发尾波场以及部分离化非线性极化强度的影响。通过非线性动力学分析的方法,得到了强激光脉冲以恒定焦斑半径传播时的激光、等离子体参数匹配条件。研究表明：在部分离化等离子体中,激光自聚焦随着电离程度的增大而增强;有质动力激发的尾波场进一步增强激光脉冲的自聚焦;相对于等离子体密度而言,激光强度对激光脉冲的自聚焦更有影响。     

利用质子能损诊断部分电离等离子体靶中的束缚电子密度

部分电离等离子体是惯性约束聚变燃料及天体等离子体中的重要组成部分,该等离子体的输运及流体力学等性质受到束缚电子的显著影响,然而当前基于光谱学的技术手段难以对其进行高精度诊断.本文基于中国科学院近代物理研究所低能离子束与等离子体相互作用实验平台,精确测量了100 ke V质子束穿过部分电离氢等离子体靶后的能损,该能损是质子同靶区内自由电子与束缚电子碰撞共同作用的结果.利用已有的能损理论模型,结合激光干涉诊断获得的自由电子密度信息,最终得到了部分电离氢等离子体靶中沿离子路径上的束缚电子密度,并给出了该等离子体的离化度参数.该离子束诊断技术具有在线、原位、分辨率高等优势,为解决部分电离等离子体内部束缚电子密度的诊断问题提供了新的途径.     

亚皮秒太瓦脉冲激光与物质相互作用研究进展

当前亚皮称太瓦超短冲激光技术的发展为激光与物质相互作用领域提供了许劝人心的研究机会，从激光与单个原子的相互作用到激光等离子体中的集体效应，如原子的高度离化、Ｘ射线激光、等离子体波导，等离子体粒子加速器，快速点火方案等等，文章评述了最近几年这方面的研究进展。     

激光在等离子体中成丝特性的数值模拟

用数值模拟方法研究激光在等离子体中成丝的发展过程及其特征参数对成丝的影响。模拟结果清晰地给出柱状成丝不稳定性的产生及发展。计算结果表明：入射激光强度、入射激光波长及等离子体背景密度是影响会聚强度的重要因素。该结果与国外报道的理论和实验研究吻合,可为研究抑制成丝提供参考。     

激光在等离子体中成丝特性的数值模拟

 用数值模拟方法研究激光在等离子体中成丝的发展过程及其特征参数对成丝的影响。模拟结果清晰地给出柱状成丝不稳定性的产生及发展。计算结果表明：入射激光强度、入射激光波长及等离子体背景密度是影响会聚强度的重要因素。该结果与国外报道的理论和实验研究吻合,可为研究抑制成丝提供参考。     

超强线极化激光在e-p等离子体中传播的成丝不稳定性

基于超强线极化激光在正负电子对(e-p)等离子体中的传播方程,讨论了相互作用过程中的成丝不稳定性。得到了电磁波的非线性色散关系和不稳定性增长率,并讨论了传播过程中激光强度和等离子体温度对成丝不稳定性的影响。结果表明,成丝不稳定性的强弱主要由相互作用的非线性效应与受有质动力作用后等离子体密度的减小之间的竞争所决定。     

超强线极化激光在e-p等离子体中传播的成丝不稳定性

基于超强线极化激光在正负电子对（e-p）等离子体中的传播方程,讨论了相互作用过程中的成丝不稳定性。得到了电磁波的非线性色散关系和不稳定性增长率,并讨论了传播过程中激光强度和等离子体温度对成丝不稳定性的影响。结果表明,成丝不稳定性的强弱主要由相互作用的非线性效应与受有质动力作用后等离子体密度的减小之间的竞争所决定。     

Filamentation of laser radiation in DC biased GaAs

In this paper, we have examined the filamentation instability of laser radiation in a GaAs sample in the negative differential resistivity region. A dc electric field is applied to assist the laser beam transferring electrons in the conduction band from the lower valley to upper satellite valleys, i.e. in increasing the effective mass of electrons. The instability causes the space charge perturbations in the microwave range of frequencies. The nonlinearity arises through the energy dependence of the effective mass and the ponderomotive force on the electrons. The instability has finite frequency and possesses large growth rate which is greatly influenced by the dc electric field.     

黑腔中空间束匀滑光束成丝不稳定性的数值模拟北大核心CSCD

为深入研究黑腔内激光成丝不稳定性产生和发展,建立了空间束匀滑光束的传播模型,利用三维激光等离子体相互作用程序LAP3D模拟了黑腔物理条件下的大尺度成丝现象。模拟结果可正确描述成丝后光强的束发散现象及谱空间光强分布特征。从激光能量参数角度分析了导致成丝不稳定性发展的物理因素,并讨论了应用空间束匀滑技术抑制成丝不稳定性的局限性。研究表明:空间束匀滑光束发展成丝的能力取决于光斑内小焦斑的成丝表现,当具备成丝能力的小焦斑份额达到一定比例后,就会导致整个空间束匀滑光束成丝,因此对于光斑平均功率密度较高的光束,须考虑结合其他束匀滑手段来抑制成丝发展。     

GeV electrons from ultraintense laser interaction with highly charged ions

Ultraintense laser interactions with highly charged ions are investigated using three-dimensional Monte Carlo simulations. Results show that ultraenergetic GeV electrons may be produced for highly charged ions chosen so that their electrons remain bound during the rise time of the laser pulse, and so that the electrons are ionized when the laser is near its maximum amplitude, which satisfies the best injection condition for subsequent laser acceleration.     

Transverse modulation of an electron beam generated in self-modulated laser wakefield accelerator experiments

Low energy electron beams (E approximately 300 keV) generated in a self-modulated laser wakefield accelerator experiment were observed to filament and be deflected away from the laser axis forming radial jets in the electron beam profile. At higher energies (E>900 keV), the filamentation and jets were suppressed and smooth electron beams copropagating with the laser were observed. The observed electron beam filamentation likely results from laser beam filamentation in the plasma due to relativistic self-focusing effects. The radial jets of low energy electrons are likely caused by transverse ejection of the electrons due to the radial structure of the wakefield and space charge deflection of electrons as they exit the laser focus.     

On an anomaly of the thermal filamentation mechanism in a high-power electromagnetic field of a strongly collisional plasma

It is shown that, under the conditions when the mean free path of electrons in a fully ionized plasma is small compared with the London plasma length, the thermal mechanism of inverse bremsstrahlung absorption and electronic conductivity has a stabilizing action on filamentation instability of high-power electromagnetic radiation, in contrast to the known case of comparatively low-intensity radiation. This new nonlinear property of a plasma is shown to be determined by a decrease in the effectiveness of plasma heating in a heating pumping field with increasing the intensity of radiation if electron oscillations have above-thermal rates.     

Filamentation instability in two counter-streaming laser plasmas

The filamentation instability was observed in the interaction of two counter-streaming laser ablated plasma flows,which were supersonic, collisionless, and also closely relevant to astrophysical conditions. The plasma flows were created by irradiating a pair of oppositely standing plastic(CH) foils with 1ns-pulsed laser beams of total energy of 1.7 k J in two laser spots. With characteristics diagnosed in experiments, the calculated features of Weibel-type filaments are in good agreement with measurements.     

对飞秒激光等离子体中成丝现象的研究

采用光学阴影法和散射光成像,对飞秒激光等离子体中的局域密度涨落进行了研究.在实验中观察到了成丝不稳定性现象.从理论上对有质动力引起的局域密度涨落进行了分析.分析表明,这种成丝不稳定性主要是由有质动力造成的.