共查询到20条相似文献,搜索用时 156 毫秒
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飞秒和纳秒脉冲作用下等离子体X射线辐射特性 总被引:1,自引:0,他引:1
对飞秒和纳秒激光作用下的Al和Cu等离子体的X射线辐射进行了测量,分析和比较。实验结果表明在飞秒激光脉冲下等离子体X射线峰值向短波方向移动。 相似文献
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分析了常规金属靶激光等离子体源产生固体碎屑的原因及其对软X射线光学元件的危害,介绍了近年来发展起来的无碎屑激光等离子体软X射线源,归纳了无碎屑激光等离子体软X射线源的几种形式和特点,并且描述了这种新型光源在软X射线显微术及光刻术中的应用. 相似文献
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本文报导激光等离子体辐射X射线的测量方法和结果。在“星光”装置上,用1.6μm激光辐照Na/F和铜靶。用平晶谱仪测量等离子体辐射X射线绝对强度,并研究了辐射X射线强度与入射激光功率密度的关系,测量了靶前后辐射强度之比,为光电离机制的X光激光研究提供了较重要的数据。 相似文献
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非同轴双束激光产生的等离子体辐射 总被引:1,自引:0,他引:1
采用非同轴双束激光,可得到时空差可控的二束不同性质的等离子体,实现在绝对同等条件下研究多束等离子体辐射的空间非均匀性和等离子体喷射对线加宽的影响。实验结果显示出在最简单的实验装置上实现等离子体强X射线泵浦X射线激光方案的可能性。 相似文献
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Masaki Oba Yoichiro Maruyama Katsuaki Akaoka Masabumi Miyabe Ikuo Wakaida 《Applied Physics A: Materials Science & Processing》2010,101(3):545-549
Emission characteristics of gadolinium (Gd) oxide are studied, using ns and fs laser pulses for ablation in double-pulse laser
induced breakdown spectroscopy (LIBS). In the current conditions of pulse energy and signal detection timing, emission intensity
enhancement in the reheating mode is 25-fold, but little effect can be observed in a pre-pulse mode. It is shown that the
optimum focus position of the ablation pulse is about 5 mm apart from the sample surface in the reheating mode. Although little
emission can be observed in the single-pulse configuration with fs ablation pulses, the intense emission can be observed in
the reheating mode in the double-pulse configuration. 相似文献
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S. S. Harilal N. Farid J. R. Freeman P. K. Diwakar N. L. LaHaye A. Hassanein 《Applied Physics A: Materials Science & Processing》2014,117(1):319-326
The collisional effects of a background gas on expanding ultrafast and short pulse laser ablation plumes were investigated by varying background pressure from vacuum to atmospheric pressure levels. For producing Cu ablation plumes, either 40 fs, 800 nm pulses from a Ti: Sapphire laser or 6 ns, 1,064 nm pulses from a Nd:YAG laser were used. The role of background pressure on plume hydrodynamics, spectral emission features, absolute line intensities, signal to background ratios and ablation craters was studied. Though the signal intensities were found to be maximum near to atmospheric pressure levels, the optimum signal to background ratios are observed ~20–50 Torr for both ns and fs laser ablation plumes. The differences in laser–target and laser–plasma couplings between ns and fs lasers were found to be more engraved in the crater morphologies and plasma hydrodynamic expansion features. 相似文献
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本文使用不同激光能流(18 J/cm2–115 J/cm2)和脉冲宽度(50 fs–4 ps)的超短脉冲激光在真空中(4×10-4 Pa)烧蚀高定向热解石墨. 通过测量烧蚀喷射物的时间分辨发射光谱研究喷射物的超快时间演化. 在喷射物发射光谱中, 观察到了C2基团的天鹅带光谱系统, 416 nm附近C15基团的由电子能级1Σu+ 和1Σg+之间的振动跃迁产生的光谱峰以及连续谱. 50 fs, 115 J/cm2的脉冲激光烧蚀产生的喷射物的连续谱的强度衰减分为快速下降和慢速下降两个阶段(以20 ns时间延迟为分界). 这表明连续谱是由两种不同的组分贡献的. 快速下降阶段, 连续谱主要由碳等离子体通过韧致辐射产生; 慢速下降阶段, 连续谱主要由烧蚀后期产生的大颗粒碳簇的热辐射贡献. 实验结果还揭示了激光能流的提高, 会明显增加喷射物中碳等离子体和激发态C2的含量, 但对质量稍大的C15的影响较小; 此外, 50 fs脉冲激光烧蚀产生的连续谱的存在时间会随着激光能流的减小而增大, 这说明低能流更有利于在烧蚀后期产生碳簇. 脉宽主要影响喷射物连续谱的时间演化. 4 ps脉冲激光烧蚀产生的连续谱的整个时间演化过程明显慢于50 fs脉冲产生的连续谱. 相似文献
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S. Canulescu E. Papadopoulou D. Anglos T. Lippert M. J. Montenegro S. Georgiou M. D?beli A. Wokaun 《Applied Physics A: Materials Science & Processing》2011,105(1):167-176
Thin films of La0.6Ca0.4CoO3 were grown by pulsed laser ablation with nanosecond and femtosecond pulses. The films deposited with femtosecond pulses (248 nm,
500 fs pulse duration) exhibit a higher surface roughness and deficiency in the cobalt content compared to the films deposited
with nanosecond pulses (248 nm, 20 ns pulse duration). The origin of these pronounced differences between the films grown
by ns and fs ablation has been studied in detail by time-resolved optical emission spectroscopy and imaging. The plumes generated
by nanosecond and femtosecond ablation were analyzed in vacuum and in a background pressure of 60 Pa of oxygen. The ns-induced
plume in vacuum exhibits a spherical shape, while for femtosecond ablation the plume is more elongated along the expansion
direction, but with similar velocities for ns and fs laser ablation. In the case of ablation in the background gas similar
velocities of the plume species are observed for fs and ns laser ablation. The different film compositions are therefore not
related to different kinetic energies and different distributions of various species in the plasma plume which has been identified
as the origin of the deficiency of species for other materials. 相似文献
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X. Zhu A.Yu. Naumov D.M. Villeneuve P.B. Corkum 《Applied Physics A: Materials Science & Processing》1999,69(7):S367-S371
We report experimental results of drilling micro holes in Al, Mo, Ti, Cu, Ag, Au, and brass thin metal foils in air using 60-femtosecond Ti:sapphire laser pulses. The influence of laser parameters and material properties on drilling processes at the sub-10-micron scale has been examined. Comparison of hole drilling using 60-fs pulses with that using 50-ps and 10-ns pulses at an energy fluence of ~15 J/cm2 indicates that a significant amount of melting is present in both ps and ns regimes, whereas with fs pulses, fewer and much smaller droplets from the molten phase are observed. 相似文献
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Cheng-Hsiang Lin Zhi Liang Jun Zhou Hai-Lung Tsai 《Applied Physics A: Materials Science & Processing》2014,116(1):119-123
For many material processes, desired radical species at excited states are produced which interact with a given substrate for a certain period of time allowing chemical reactions between them to occur and complete. Hence, it is important to maintain the population of the excited radical species for an extended period of time, i.e., their lifetime, which is defined as the time for emission intensity to decay to 1/e of the initial intensity. In this study, a femtosecond–nanosecond (fs–ns) dual-laser system was employed to generate desired radical species via the fs laser and, then, to extend the lifetime of the radical species by the ns laser with different time delays between the two fs–ns laser pulses. The proposed method is demonstrated for a N2–CO2 mixture with CN as the radical species. The results show that the lifetime of CN radical species can be significantly extended, particularly the (3, 3) spectral line which was extended from 30 to 200 ns. By using a wavelength-tunable ns laser, the lifetime of most radical species can be extended which may increase the process efficiency for many material processes. 相似文献
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用腔倒空Nd:YAG激光器对fs超短脉冲的同步放大 总被引:1,自引:1,他引:0
实现了用腔倒空Nd:YGA激光器对fs超短脉冲放大器的同步泵浦。由碰撞锁模环形染料激光器产生的80fs脉冲经二级染料放大后,实现放大倍数6.2×10~4,输出超短脉冲峰值功率~2×10~7W。 相似文献
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Thomas Lehecka Andrew Mostovych Jeffrey Thomas 《Applied Physics A: Materials Science & Processing》2008,92(3):727-741
Time resolved emission from the interaction of ultra-short (∼200 fs) laser pulses with aluminum and copper targets was investigated.
Measurements show that emission from the laser produced plasma in air is significantly more intense than in near vacuum conditions
and that the emission in air can extend for periods exceeding 100 ns. Modeling the laser–target–air coupling shows that the
laser–target interaction can lead to blast wave shock waves being launched in the ambient air and that the emission from the
shocked air dominates over emission from the target surface. The long term emission measurements in air are in agreement with
the modeling results. 相似文献
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