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941.
942.
用混沌动力学方法对多道扫描静电探针的离子饱和电流信号进行分析,研究了等离子体尾迹流场.通过对相关维、Renyi熵和最大Lyapunov指数的分析,得到了近尾流场的分层结构.利用最大Lyapunov指数,观测到了在x>10D以后的远尾流场与自由流场相似.结合探针信号的自相关函数,研究流场湍流结构,发现近尾可能存在大涡拟序结构,而在远尾则没有湍流.观察到了流场具有一定的间歇特征,认为这种间歇性与湍流有关.结果还表明,混沌动力学的分析方法对信号中非周期成分十分敏感,在研究等离子体尾迹流场这一类非线性系统时,它具有明显的优越性
关键词:
混沌动力学
尾迹
等离子体湍流
静电探针 相似文献
943.
We report laser oscillations in Cd II on 4d
95s
2
2
D
5/2 − 4d
105p
2
P
3/2 transition at 441.6 nm using laser produced tungsten plasma as a pumping source. Mach Zehnder interferometer is used to measure
electron density. Design and working of the crossed heat pipe used in the studies is discussed. 相似文献
944.
强激光和稠密等离子体相互作用产生的三次谐波 总被引:1,自引:1,他引:0
研究了超强激光和均匀及线性梯度高密度等离子体相互作用产生的三次谐波,特别研究了等离子体密度为四倍临界密度时的情形,这可能是用相对论效应产生高效谐波的最佳密度。 相似文献
945.
Chen I.-H. Chu S.-W. Sun C.-K. Cheng P.-C. Lin B.-L. 《Optical and Quantum Electronics》2002,34(12):1251-1266
Molecular excitation by the simultaneous absorption of two photons provides intrinsic three-dimensional resolution in laser scanning fluorescence microscopy. Thus induced two-photon absorption and the accompanied multi-photon absorption/ionization not only cause photo-bleaching but also cell damage in the vicinity of the focal point. In this paper, we study the wavelength dependent cell damage induced by high intensity femtosecond near infrared lasers. The study was performed with a Ti:sapphire laser and a Cr:forsterite laser. With a longer output wavelength from a Cr:forsterite laser, multi-photon absorption and auto-fluorescence were found to be significantly suppressed and the destructive plasma formation was found to be greatly reduced. Sustained multi-photon spectra can be observed in most plant specimens with a tightly focused Cr:forsterite laser beam under long term irradiation with more than 100 mW laser average power. In contrast, multi-photon absorption induced destructive plasma formation were frequently observed with a tightly focused Ti:sapphire laser beam within seconds with more than 10 mW laser average power. 相似文献
946.
V. I. Nasonov 《Journal of Applied Spectroscopy》2006,73(2):234-244
Radiation scattering by particles of condensed phase in an ablation plasma plume has been experimentally studied during quasicontinuous
laser irradiation (λ = 1.06 μm, q = 0.1–9 MW/cm2, τ ∼ 1.5 msec) of duraluminum D16T, aluminum A99, and bismuth. The particle size distribution and the nature of their dispersal
during irradiation was studied in scattered light (λ = 0.69 μm) from individual particles that could be visually observed
on photographs. It was found that under the pressure developed in the plume, large particles ejected from the irradiated zone
can move backward and return to the target (D16T). The plume (Bi) becomes brighter due to ablation of particles in the path
of the laser beam. The directional scattering coefficients for scattering from the local zone on the axis of the plume, measured
during the laser pulse, were used to study the relationship between the dynamics of entry of condensed phase into the plume,
shielding of the target by the particles, and brightening of the plume under the action of the incident laser radiation.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 210–219, March–April, 2006. 相似文献
947.
Comparative Study of Plasma Spray Flow Fields and Particle Behavior Near to Flat Inclined Substrates
Numerical models have been developed using computational fluid dynamics (CFD) analysis program FLUENT V6.02© to investigate the effect of the substrate on the behavior of the plasma flow fields and in-flight particles. Simulations are performed for cases where flat substrates are either present or absent, for the former, the substrate is oriented perpendicularly or inclined to the torch axis. It is shown that although the presence of perpendicular or inclined substrate significantly influences the plasma flow fields at the vicinity of the substrate, the particle behavior remain relatively unaffected. The insignificant effect of the substrate on particle behavior is qualitatively verified by experimental observation using SprayWatch© imaging diagnostics equipment. Images captured by the equipment confirm that the particles travel through the plasma plume with high momentum and show no sudden change in theirtrajectories right before impacting the substrate. Both the numerical and experimental findings show that the freestream model is sufficiently detailed for future work of this nature. 相似文献
948.
For the first time, the dissipation of laser-radiation energy in the gas surrounding a target is investigated under the conditions
of intense plasma formation near a surface and the existence of large spots of: irradiation. The parameters of different regions
of the heated gas are measured and an energy balance of the process of laser effects is obtained.
Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 6, pp. 814–817, November–December, 1998. 相似文献
949.
Kalman滤波法消除光谱连续背景的研究 总被引:1,自引:0,他引:1
本文研究了Kalman滤波法消除光谱连续背景,以电感耦合等离子体原子发射光谱法测量氧化铽中La,Er,Gd,Dy,Du和Tm为例研究了不同背景情况下的结果。用新息序列的平均平方和正交自相关系数超过出信度极限以外数为评价函数,可评价所估计的背景形状,是一种不用测背景,用计算方法消除光谱连续背景的好方法,本方法不仅适用于电感耦合等离子体原子发射光谱,对分光光度,原子等原则上都可适用。 相似文献
950.
电磁波的非线性动力理论 总被引:1,自引:1,他引:0
使用全动力途径,严格地推导了左旋圆极化电磁波的非线性色散关系。所得到的色散关系被用来分析电子Bernstein波和高杂波所激发的电磁辐射。结果表明:(1)电子Bernstein波可以激发频率上移辐射,也可以激发频率下移辐射,这取决于背景等离子体频率wpe与电子回旋频率Ωe的比值大小;(2)高杂波只能激发频率下移辐射;(3)当电子Bernstein波位于高杂共振层时,频率上移辐射和频率下移辐射可以同 相似文献