共查询到18条相似文献,搜索用时 343 毫秒
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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。 相似文献
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张家泰 《工程物理研究院科技年报》2003,(1):103-104
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。 相似文献
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亚皮秒太瓦脉冲激光与物质相互作用研究进展 总被引:1,自引:0,他引:1
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。 相似文献
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应用强场理论、多光子非线性Compton散射模型和场论方法,对非线性Compton散射对超强激光在等离子体中坍塌的影响进行了理论分析,提出了将入射超强激光和多光子非线性Compton散射光作为超强激光在等离子体中坍塌的新机制,通过构造超强激光非线性控制方程的拉格朗日密度函数,给出了激光包络尺度变化的修正方程.结果表明:多光子非线性Compton散射加剧了激光包络调制不稳定性的非线性发展及物质密度局部稀化形成密度空穴的进程,使横等离激元和局部场强迅速增强,从而导致初始均匀分布激光场的剧烈坍塌. 相似文献
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质谱在激光等离子体物理研究中的应用 总被引:1,自引:0,他引:1
在对激光等离子体相互作用的研究中,物质由于在激光场的作用下离子化而成各种离化态的离子,研究这些离子的特性可以深入理解激光与等离子体相互作用过程,质谱仪能提供离子的最高离化态、平均电荷态、能量分布和丰度等重度信息,文章介绍了质谱仪的原理及的原理及其在激光等离子体中的应用。 相似文献
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强激光在冕区等离子体中传播到临界面附近生成相对论电子和相对论电子束流在随后较长一段稠密等离子体区的能量传输是快点火中的关键问题。对快点火条件下的激光等离子体参数,临界面附近产生的前向快电子电流往往超过阿尔芬极限电流,必须在稠密等离子体中产生中和回流,快电子流才能在稠密等离子体中向前输运。横向电磁不稳定性(类Weibel不稳定性,WI)和纵向静电双流不稳定性(TSI)很容易在这种电子双流体系中激发,前向电子束会被调制或成丝状结构,同时激发电磁场,粒子部分动能会转化为电磁场能量。不稳定性在非线性饱和后,发生电流丝的合并、磁场重联等过程,部分电磁场能量会再转化为粒子能量,表现为对离子体的横向加热。Weibel不稳定性的作用可能形成围绕传播电子束的磁通道,对快电子的定向和准直传播是重要的。TSI激发的纵向静电场对磁场通道会有明显的调制甚至破坏作用,直接影响高能电子流从激光吸收区到燃料压缩区的准直传播。 相似文献
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应用强场理论、多光子非线性Compton散射模型和场论方法,对非线性Compton散射对超强激光在等离子体中坍塌的影响进行了理论分析,提出了将入射超强激光和多光子非线性Compton散射光作为超强激光在等离子体中坍塌的新机制,通过构造超强激光非线性控制方程的拉格朗日密度函数,给出了激光包络尺度变化的修正方程。结果表明:多光子非线性Compton散射加剧了激光包络调制不稳定性的非线性发展及物质密度局部稀化形成密度空穴的进程,使横等离激元和局部场强迅速增强,从而导致初始均匀分布激光场的剧烈坍塌。 相似文献
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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. 相似文献
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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。 相似文献
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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. 相似文献
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Moore CI Krushelnick K Ting A Burris HR Hubbard RF Sprangle P 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》2000,61(1):788-792
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. 相似文献
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V. P. Silin 《Journal of Experimental and Theoretical Physics》2001,92(4):617-625
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. 相似文献
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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. 相似文献
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The filamentation instability of laser beams propagating in nonlocal nonlinear media is investigated. It is shown that the filamentation instability can occur in weakly nonlocal self-focusing media for any degree of nonlocality, and in defocusing media for the input light intensity exceeding a threshold related to the degree of nonlocality. A linear stability analysis is used to predict the initial growth rate of the instability. It is found that the nonlocality tends to suppress filamentation instability in self-focusing media and to stimulate filamentation instability in self-defocusing media. Numerical simulations confirm the results of the linear stability analysis and disclose a recurrence phenomenon in nonlocal self-focusing media analogous to the Fermi-Pasta-Ulam problem. 相似文献