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61.
62.
C. Labaune K. Lewis H. Bandulet S. Depierreux S. Hüller P. E. Masson-Laborde D. Pesme P. Loiseau 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):283-288
Many nonlinear processes may affect the laser beam propagation and the laser
energy deposition in the underdense plasma surrounding the pellet. These
processes, associated with anomalous and nonlinear absorption mechanisms,
are fundamental issues in the context of Inertial Confinement Fusion. The
work presented in this article refers to laser-plasma interaction
experiments which were conducted under well-controlled conditions, and to
their theoretical and numerical modeling. Thanks to important diagnostics
improvements, the plasma and laser parameters were sufficiently
characterized in these experiments to make it possible to carry out
numerical simulations modeling the laser plasma interaction in which the
hydrodynamics conditions were very close to the experimental ones. Two sets
of experiments were carried out with the LULI 2000 and the six beam LULI
laser facilities. In the first series of experiments, the interaction
between two single hot spots was studied as a function of their distance,
intensity and light polarization. In the second series, the intensity
distribution of stimulated Brillouin scattering (SBS) inside the plasma was
studied by means of a new temporally resolved imaging system.
Two-dimensional (2D) simulations were carried out with our code Harmony2D in
order to model these experiments. For both series of experiments, the
numerical results show a very good agreement with the experimental ones for
what concerns the main SBS features, namely the spatial and temporal
behavior of the SBS-driven acoustic waves, as well as the average SBS
reflectivities. Thus, these well diagnosed experiments, carried out with
well defined conditions, make it possible to benchmark our theoretical and
numerical modelings and, hence, to improve our predictive capabilities for
future experiments. 相似文献
63.
S. Ghosh Nishchhal Yadav 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(2):173-178
Using the hydrodynamical model and following the coupled mode approach, detailed analytical investigation of stimulated Brillouin
scattering is performed in an electrostrictive semiconductor. The total induced current density including diffusion current
density and the effective Brillouin susceptibility are obtained under off-resonant laser irradiation. The analysis deals with
the qualitative behaviour of the Brillouin gain and transmitted intensity with respect to excess doping concentration and
magnetic field. Efforts are directed towards optimizing the doping level and magnetic field to achieve maximum Brillouin gain
at pump intensities far below the optical damage threshold level. It is found that by immersing a moderately doped semiconductor
in a sufficiently strong magnetic field in transverse direction, one can achieve resonant enhancement of Brillouin gain provided
the generated acoustic mode lies in the dispersionless regime. 相似文献
64.
In this article, based on a set of upper record values from a Rayleigh distribution, Bayesian and non-Bayesian approaches have been used to obtain the estimators of the parameter, and some lifetime parameters such as the reliability and hazard functions. Bayes estimators have been developed under symmetric (squared error) and asymmetric (LINEX and general entropy (GE)) loss functions. These estimators are derived using the informative and non-informative prior distributions for σ. We compare the performance of the presented Bayes estimators with known, non-Bayesian, estimators such as the maximum likelihood (ML) and the best linear unbiased (BLU) estimators. We show that Bayes estimators under the asymmetric loss functions are superior to both the ML and BLU estimators. The highest posterior density (HPD) intervals for the Rayleigh parameter and its reliability and hazard functions are presented. Also, Bayesian prediction intervals of the future record values are obtained and discussed. Finally, practical examples using real record values are given to illustrate the application of the results. 相似文献
65.
根据频率选择性衰落信道的抽头延迟线模型,将针对平坦衰落信道的CS(周期平稳过程理论)频偏盲估计算法扩展到了频率选择性衰落信道,并通过仿真证明这种扩展是可行的.仿真结果还表明CS算法不仅有好的抗平坦衰落能力,而且有很好的抗频率选择性衰落性能. 相似文献
66.
在pH 2.0~6.0的BR缓冲溶液中, Pd(II)与柠檬黄(TTZ)形成的络离子与溴化1-十六烷基-3-甲基咪唑([C16mim]Br)离子液体发生作用形成离子缔合物, 引起溶液共振瑞利散射(RRS)显著增强, 并产生新的RRS光谱, 其最大RRS峰位于458 nm. 在0.043~0.860 μg/mL范围内散射强度(ΔI)与柠檬黄的浓度成正比. 该方法简单灵敏, 对柠檬黄的检出限(3σ/K)为5.5 ng/mL (n=11). 建立了一种简便、快速测定柠檬黄的新方法, 并成功用于饮料样中柠檬黄含量的测定. 相似文献
67.
68.
In this paper, we address several optimization problems in satellite optical communications. We show that the inter-satellite links with swaying transmitters can be described as an equivalent fading model. We further indicate that the instantaneous signal-to-noise ratio follows the reciprocal Pareto distribution. Then we conduct the analysis on several performance metrics such as the first and second moments of signal-to-noise ratio, the amount of fading, as well as the outage probability. Based on these metrics, we establish optimization models and provide the corresponding solutions. 相似文献
69.
70.
设计了采用532 nm 种子注入稳频钇铝石榴石(YAG)激光器作为辐射源的基于四通道法布里-珀罗标准具的瑞利和米散射测风激光雷达系统。介绍了激光雷达的多普勒测量基本原理;给出了雷达系统的主要参数,重点对基于分子后向散射信号的外侧双通道标准具的带宽、自由谱间距、峰值间距等指标进行了详细设计与分析,确定了内侧双通道标准具参数;对全系统速度灵敏度、信噪比与探测距离的关系进行了理论模拟。结果表明,可以实现从边界层至对流层高低空一体化探测。 相似文献