共查询到15条相似文献,搜索用时 140 毫秒
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具有液氮温度和适度压强的氢气通过S99阀门Laval喷嘴进入真空,经超声绝热膨胀形成团簇。本实验用瑞利散射法测量氢团簇尺寸随阀门背压强的变化曲线。当背压为1.0MPa时,每个氢团簇平均包含250个氢原子。 相似文献
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利用瑞利散射方法研究了超声喷流Ar-CH4混合团簇和超声喷流Ar-H2混合团簇的特性.通过测量不同混合比例和不同背压下所形成混合团簇的散射信号发现,当用Ar气和CH4的混合气体进行超声喷流时很容易形成Ar-CH4混合团簇,当Ar气含量为50%时混合团簇尺度最大且大于相同气压下纯Ar团簇尺度和纯CH4团簇尺度.实验发现,与纯H2团簇只能在低温条件下获得不同,常温下即可形成Ar-H2混合团簇,实现了常温下含氢团簇的获取,从而有效降低了制备成本.在H2含量大于40%时混合团簇开始形成并在60%时达到最大尺度.含氢(氘)混合团簇在氢(氘)团簇的基础上引入了更重的异核Ar元素,在激光氘团簇聚变实验中它将进一步加速氘离子从而获得更高的能量,并具有更高的中子产额和聚变效率. 相似文献
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利用飞行时间谱,研究了在飞秒强激光场(60 fs,2×1016 W/cm2)作用下,大尺寸氩原子团簇Arn(n—=3×103—3×106原子/每团簇)的电离爆炸过程,测量了 团簇爆炸所产生的氩离子的平均能量与团簇尺寸(气体背压)的关系.实验发现,随着气体 背压的升高(团簇尺寸增大),氩离子的平均能量也相应升高.通过分析两个不同几何尺寸 锥形超声喷嘴所产生团簇爆炸后的离子能量,结合Hagena团簇尺寸规律,发现在激光参数保 持不变的情况下,离子的平均能量由团簇尺寸唯一确定.分析表明,团簇尺寸在3×105原 子/每团簇以下时,团簇膨胀的主要机理是库仑爆炸.随着团簇尺寸的进一步增大,团簇膨胀 机理将由库仑爆炸向流体动力学膨胀过渡,在3×105关键词:
原子团簇
飞秒强激光
库仑爆炸
流体动力学膨胀 相似文献
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Noble gases (argon, krypton, and xenon) are puffed into vacuum through a nozzle to produce clusters for studying laser-cluster interactions. Good estimates of the average size of the argon, krypton and xenon clusters are made by carrying out a series of Rayleigh scattering experiments. In the experiments, we have found that the scattered signal intensity varied greatly with the opening area of the pulsed valve. A new method is put forward to choose the appropriate scattered signal and measure the size of Kr cluster. 相似文献
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Study on the interaction of intense femtosecond laser pulses with nanometre-sized hydrogen clusters 下载免费PDF全文
The interaction of intense femtosecond laser pulses with hydrogen clusters
has been experimentally studied. The hydrogen clusters were produced from
expansion of high-pressure hydrogen gas (backed up to 8\tm106Pa) into vacuum
through a conical nozzle cryogenically cooled by liquid nitrogen. The
average size of hydrogen clusters was estimated by Rayleigh scattering
measurement and the maximum proton energy of up to 4.2keV has been obtained
from the Coulomb explosion of hydrogen clusters under 2×1016 W/cm2 laser irradiation. Dependence of the maximum proton energy on cluster size and laser intensity was
investigated, indicating the correlation between the laser intensity and the
cluster size. The maximum proton energy is found to be directly proportional
to the laser intensity, which is consistent with the theoretical prediction. 相似文献
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The spectra of vacuum ultraviolet luminescence of heteroatomic Ar-Xe clusters condensed in supersonic jets of a mixture of these gases at a xenon impurity concentrations of 0.001–2% are measured. A new group of molecular luminescence bands of argon-xenon centers is recorded, which allows a highly sensitive detection of xenon in the argon matrix of a cluster. The phenomenon of phase separation into pure components with formation of a sharp interface between the xenon core and argon shell of the cluster is found. 相似文献
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An Experimental Observation of Axial Variation of Average Size of Methane Clusters in a Gas Jet 下载免费PDF全文
Axial variation of average size of methane clusters in a gas jet produced by supersonic expansion of methane through a cylindrical nozzle of 0.8 mm in diameter is observed using a Rayleigh scattering method. The scattered light intensity exhibits a power scaling on the backing pressure ranging from 16 to 50bar, and the power is strongly Z dependent varying from 8.4 (Z = 3mm) to 5.4 (Z = 11mm), which is much larger than that of the argon cluster. The scattered light intensity versus axial position shows that the position of 5mm has the maximum signal intensity. The estimation of the average cluster size on axial position Z indicates that the cluster growth process goes forward until the maximum average cluster size is reached at Z - 9 mm, and the average cluster size will decrease gradually for Z 〉 9 mm. 相似文献
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Mair RW Wang R Rosen MS Candela D Cory DG Walsworth RL 《Magnetic resonance imaging》2003,21(3-4):287-292
We report initial NMR studies of continuous flow laser-polarized xenon gas, both in unrestricted tubing, and in a model porous media. The study uses Pulsed Gradient Spin Echo-based techniques in the gas-phase, with the aim of obtaining more sophisticated information than just translational self-diffusion coefficients. Pulsed Gradient Echo studies of continuous flow laser-polarized xenon gas in unrestricted tubing indicate clear diffraction minima resulting from a wide distribution of velocities in the flow field. The maximum velocity experienced in the flow can be calculated from this minimum, and is seen to agree with the information from the complete velocity spectrum, or motion propagator, as well as previously published images. The susceptibility of gas flows to parameters such as gas mixture content, and hence viscosity, are observed in experiments aimed at identifying clear structural features from echo attenuation plots of gas flow in porous media. Gas-phase NMR scattering, or position correlation flow-diffraction, previously clearly seen in the echo attenuation data from laser-polarized xenon flowing through a 2 mm glass bead pack is not so clear in experiments using a different gas mixture. A propagator analysis shows most gas in the sample remains close to static, while a small portion moves through a presumably near-unimpeded path at high velocities. 相似文献