共查询到20条相似文献,搜索用时 125 毫秒
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采用单脉冲激光进行了大气环境下激光烧蚀小钢珠实验,得到其推进效应参数,发现并分析了钢珠在不同放置位置(焦前与焦后)时不同的物理现象;为了得到一系列定量实验数据,采用自行研制的激光冲量靶仪进行了单脉冲激光烧蚀推进效应实验测试,得到了不同环境条件、不同靶材料的激光推进效应参数,并与国外的实验数据以及数值计算结果进行了比较。实验表明,靶材料和激光功率密度是影响冲量耦合系数的主要因素,冲量耦合系数随环境气压的降低而升高。 相似文献
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在准真空环境下,采用高功率密度的调Q-Nd:YAG激光照射固体铝靶表面,测量了不同入射激光强度下气化靶物质对靶的冲量.通过分析不同情况下激光与固态靶、气化物质的作用机理,采用流体力学理论和三维有限差分的计算方法,对不同激光强度情况下气化物质对靶产生冲量的过程进行了数值模拟,将模拟计算所得结果与实验测量结果进行了比较和分析,进而对实验结果进行了解释.由数值模拟结果与实验结果的一致性可见,本文采用的模型能反映激光作用下固体靶力学响应的物理过程. 相似文献
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研究了整形激光脉冲对冰冻氘氚靶的压缩。通过数值分析,发现利用分步激光产生的系列激波压缩氘氚靶可以获得较高密度和较低温度的等离子体靶。初始激光强度的选取将影响到压缩后的等离子体密度,继而影响到产生中子的数量。通过调节初始激光强度可以使压缩后的氘氚靶温度处在反应率比较高的范围内,从而得到优化结果。当初始归一化激光振幅为0.5,最终为32时,压缩后的氘氚靶密度可达到18416倍的临界密度,温度达到16 keV,每焦耳入射激光能量可得到109个中子,这个中子产额比现有其他方法所得到的中子产额大4个数量级。 相似文献
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超强超短脉冲激光广泛应用于粒子加速以及新型X射线辐射源产生。较长的激光脉冲上升前沿直接影响激光应用效果。等离子体薄膜靶作为新型光学介质开关,可以有效降低超强激光脉冲前沿上升时间,优化激光等离子体相互作用参数。采用一维理论分析和粒子模拟方法研究了等离子体薄膜靶实现超强激光脉冲整形的机制。研究结果表明,薄膜靶通过对激光脉冲的非线性调制,可有效实现脉宽缩短和脉冲陡化;对比单层靶调制结果,选择参数优化的双层靶,可进一步优化脉冲整形效果,获得更短脉宽和更高振幅的激光脉冲;对于峰值振幅高于薄膜靶击穿阈值的超强激光,脉冲上升前沿可得到明显陡化,薄膜靶的击穿是产生这种脉冲整形效果的直接原因。 相似文献
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本文提出一种基于单束激光直接加热多层平面靶开展 稠密等离子体辐射不透明度特性研究的靶物理设计并对其进行了实验验证. 在XG-II激光装置上, 采用三倍频束匀滑激光辐照Au/CH/Al/CH多层平面靶产生背光源和Al样品等离子体, 通过观测背光源经样品等离子体衰减后的透过谱得到样品等离子体的辐射吸收性质. 采用Multi-1D程序对激光加热多层靶进行了辐射流体力学数值模拟, 给出了样品等离子体状态及其时间演化过程. 利用细致谱项模型 (DTA) 对实验测量的Al等离子体吸收谱进行理论分析, 表明等离子体温度在20–70 eV之间, 该结果与辐射流体力学模拟结果基本一致.
关键词:
吸收光谱
自背光
激光等离子体 相似文献
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强激光与红外光学系统光轴平行性检测方法的探讨 总被引:1,自引:2,他引:1
介绍3种可测量强激光发射光轴与红外光轴平行性的方法及每种方法的优缺点,重点研究了利用热靶进行波段转换来测量激光与红外光学系统光轴平行性的方法。该方法是将激光聚焦在热靶上,使热靶产生热量并发出红外光,红外光再经过准直进入被测设备的红外光学系统,从而测量出激光光轴与红外光轴的平行性。热靶材料的选择与激光透过率的确定尤为重要,该方法中选用酚醛树脂作为热靶材料,激光的透过率仅为0.5%。通过与远距离目标靶测量法进行比对实验,发现2种方法得到的测量结果一致,从而验证了这种方法的可行性与正确性。 相似文献
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The potential function derived from experimental structure factor data gives a repulsive minimum and also an attractive minimum. These two minima correspond to the first and second nearest-neighbour distances. Similar results have been obtained through the use of Percus-Yevick (PY) and hyper-netted chain (HNC) equations. The Hafner molecular dynamics results also show a similar trend. The first, second and third derivatives of the potential function have been obtained from the expression of the potential function. The first and second derivatives have been used to compute the phonon frequencies using Bhatia and Singh's (BS) method. The phonon frequencies obtained from Hubbard and Beeby's (HB) method show similar results. The elastic constants have also been calculated and the values obtained for C11 by different methods are in good agreement. The Grüneisen constant has been calculated by two different methods which are in very good agreement with each other. From the Grüneisen constant the pressure derivative of the diffusion coefficient has been obtained and has been compared with that of Swalin's equation. The results are in excellent agreement with each other. 相似文献
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Hydromagnetic turbulent shear flow of viscous, incompressible, electrically conducting fluid between two infinite uniformly porous moving parallel planes in the presence of axial and transverse magnetic field has been studied by the semi-empirical method. The expressions for the mean distributions for velocity and magnetic field for turbulent shear flow have been obtained for both the cases. As particular cases, the results have been obtained if the planes are fixed. The solutions obtained when the magnetic field is axial have been shown graphically for turbulent and laminar flows. 相似文献
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在椭球坐标系下,采用B样条基组方法计算了磁场范围在0-1000 a.u.下氢原子低能态能量以及实验室磁场下(几个特斯拉)氢原子里德堡态的能级,并与文献中的精确结果进行了比较.对1s0态,磁场γ≤100 a.u.时,本文计算结果有12位有效数字的精度,γ=1000 a.u.时有11位有效数字的精度.对2p-1低激发态,γ≤100 a.u.时,能量至少有11位有效数字的精度;γ=1000 a.u.时,有9位有效数字的精度.对原子高激发态,我们计算了实验室磁场下(磁场为4.7特斯拉)氢原子里德堡态(主量子数n=23)的抗磁谱,得到了至少10位有效数字精度的能谱.本文方法既适用于超强磁场下低能态的计算,同样适合原子高里德堡态抗磁谱的计算,为精确计算强磁场下原子能谱提供了一个新的可行方案.此外,讨论了本文方法推广到平行及交叉电磁场下原子能谱计算的可行性. 相似文献
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Fokker-Planck type equations have been classified according to the groups of contact transformations to which they belong.
It has been found that there are only five classes as in the case of groups of point transformations. We have also obtained
the algebraic structures of the corresponding Lie algebras. However, there are isomorphies in their group properties. The
corresponding basis sets of functionally independent invariants formed by the generators of these groups have also been obtained. 相似文献
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The fluorescence and fluorescence excitation spectra of a number of pesticidal carbamates have been recorded at room temperature and at 77 K. The phosphorescence and phosphorescence excitation spectra of the same molecules, in EPA at 77 K, have been obtained. The phosphorescence lifetimes of three molecules have been determined using two different techniques. The fluorescence yields and decomposition yields have also been recorded. The data obtained are not only of basic interest but may be useful in environmental studies. 相似文献
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V.P. Gupta V.K. Srivastava P.N.L. Gupta 《Journal of Physics and Chemistry of Solids》1981,42(12):1079-1085
Using Phillips and Van Vechten theory [1–3], the values of the homopolar gap, ionic gap and Penn gap have been evaluated for thirty-one chalcopyrites. The values so derived have been found in accordance with the values obtained from the Penn model and the Phillips model. Using the above parameters the microhardness has been determined. The values obtained are in agreement with experimental data. The electronic polarizabilities have also been evaluated using the Clausius-Mossotti relation. The values are in agreement with the ordinary sums of the polarizabilities of individual bonds. 相似文献
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A B-spline-type basis set method for the calculation of hydrogen atom in strong magnetic fields in the frame of spheroidal
coordinates has been introduced. High accurate energy levels of hydrogen in the magnetic field, with strength ranging from
0 to 1000 a.u., have been obtained. For the ground state, 1s0, energies with at least 11 significant digits have been obtained. For the low-lying excited state, 2p−1, energies with at least 9 significant digits are obtained. The method has also been applied to the calculation of hydrogen
Rydberg states in laboratory magnetic fields. Energy spectra with at least 10 significant digits are presented. A comparison
with other results in the literatures has been performed. Our results are comparable to the most accurate one up to date.
A possible extension to the cases of parallel and crossed electric and magnetic fields have been discussed. 相似文献
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Subenoy Chakraborty Tanwi Bandyopadhyay 《International Journal of Theoretical Physics》2009,48(5):1369-1378
A detailed investigation of Gauss-Bonnet theory has been done from a different perspective. At first, the standard energy
conditions are discussed and modified forms have been presented. Then some cosmological solutions have been obtained in 5D
for perfect fluid assuming that the extra dimensional metric coefficient decreases with time. For some particular choice of
the parameters, exponential solutions are obtained and finally, Cosmic No-Hair Conjecture has been proved for Gauss-Bonnet
dilatonic scalar coupled to Einstein gravity with coupling parameter growing linearly in time. 相似文献
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Volkerts M Bacelar JC van Goethem MJ Harakeh MN Hoefman M Huisman H Kalantar-Nayestanaki N Kopecky S Löhner H Messchendorp JG Nakayama K Ostendorf RW Schadmand S Scholten O Wilschut HW 《Physical review letters》2004,92(20):202301
Data on proton-neutron bremsstrahlung have been obtained from a measurement of the quasifree breakup channel in proton-deuteron bremsstrahlung. This high-precision measurement, with an incident proton energy of 190 MeV, is fully exclusive; i.e., the protons, the neutron, and the photon have been detected. The quasifree differential cross sections obtained are compared with microscopic calculations and calculations based on soft-photon models. There are sizable differences between the models and also between the models and the data obtained for this simple process. 相似文献
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M.P. Madan 《Journal of Molecular Liquids》1984,29(3):161-171
Molecular relaxation studies have been made on rigid polar solutes dibenzofuran and s-trioxane and their mixtures with benzophenone, ortho- and meta-dichlorobenzenes in the microwave region over a range of temperatures in dilute benzene solutions. The relaxation times and the thermodynamic parameters for the activated state have been determined using the measured dielectric data. The results obtained have been discussed in terms of the molecular motion of the system and are consistent with those of other rigid molecules studied previously. The results are also compared with the computed values obtained by employing a relation proposed by us earlier. 相似文献