共查询到19条相似文献,搜索用时 125 毫秒
1.
针对神光Ⅱ第九路激光条件,利用1维JB程序和多台阶靶技术对冲击波在铝 金阻抗匹配靶中的传播稳定性进行了理论和实验研究,实验结果与理论结果基本吻合。结果表明,激光驱动冲击波在铝 金阻抗匹配靶中传播时,高阻抗待测材料金中的冲击波稳定传播最大距离急剧减小。因此,在进行铝-金阻抗匹配靶物理参数设计时,应保证高阻抗材料金台阶厚度满足冲击波传播稳定性,然后再按照阻抗匹配实验中两种材料的冲击波速度比来确定低阻抗标准材料铝的台阶厚度。根据神光Ⅱ第九路激光条件,铝-金阻抗匹配靶中铝基底厚度选取为30 μm左右较好,金台阶和铝台阶厚度应分别小于10 μm和17 μm。 相似文献
2.
3.
利用一维辐射流体力学数值模拟程序对激光驱动的冲击波在平面铝靶中传播的实验结果进行了模拟研究.分析了空间单元层的厚度对模拟结果的影响,给出了最佳单元层厚度.通过将数值模拟与实验结果相比较给出了实验中两种激光光强的实际的吸收系数.结果显示,波长为1.053μm,强度分别为0.81×1014和1.65×1014W/cm2的激光驱动的冲击波在铝靶中传播速度分别为16.52,18.56μm/ns,冲击波的峰值压力分别为0.386和0.537TPa,这些模拟结果与实验结果是一致的
关键词:
冲击波
辐射流体力学
激光等离子体 相似文献
4.
5.
6.
7.
8.
9.
10.
辐射驱动下主动式高精度冲击波速度精密诊断技术 总被引:1,自引:0,他引:1
激光加载可以产生比气泡加载更高的压力,是高压状态方程研究中一种新的加载方式。在激光加载高压状态方程(EOS)研究中,台阶靶是常用的靶型。针对传统台阶靶存在的预热膨胀问题,提出了使用主动式任意反射面速度干涉仪(VISAR)进行台阶靶预热和冲击波测量的方法。该技术利用条纹图移动量计算厚度增加量,利用冲击波到达自由面产生条纹跳变的时刻来获得精确的冲击波到达时刻。通过修正已测量台阶厚度与膨胀量,可以获得更加精确的台阶厚度值。通过精确的时间间隔可以得到冲击波传输的时间。在匀速传输的条件下可以获得高精度的冲击波传输速度。该方法在辐射驱动超高压条件下具有很好的适用性,可以为状态方程实验提供高精度的冲击波速度数据。 相似文献
11.
The influence of air pressure on mechanical effect of laser plasma shock wave in a vacuum chamber produced by a Nd:YAG laser has been studied. The laser pulses with pulse width of 10ns and pulse energy of about 320mJ at 1.06μm wavelength is focused on the aluminium target mounted on a ballistic pendulum, and the air pressure in the chamber changes from 2.8 × 10^ 3 to 1.01 × 10^5pa. The experimental results show that the impulse coupling coefficient changes as the air pressure and the distance of the target from focus change. The mechanical effects of the plasma shock wave on the target are analysed at different distances from focus and the air pressure. 相似文献
12.
为了研究强脉冲激光在镁合金中诱导冲击波的衰减,采用Nd:Glass脉冲激光(1054 nm,23 ns)对AZ31B变形镁合金试样表面进行冲击,并利用响应快、测量范围大的PVDF压电膜传感器以及示波器实时测量了强脉冲激光在镁合金靶中诱导激光冲击波的相对压力.根据冲击波每次在靶材背面反射时,所经过距离的不同得到激光冲击波在镁合金中的衰减规律.结果表明,在激光能量为5J的强脉冲激光作用下,镁合金中冲击波衰减的平均速度为5.83×103 m/s,与镁合金中应力波纵波的传播速度相符;强脉冲激光诱导冲击波在镁合金中是以指数规律衰减的.试验所得分析结果对激光冲击强化镁合金的应用具有重要意义.
关键词:
激光
镁合金
压电膜传感器
衰减规律 相似文献
13.
Shadowgraph investigation of plasma shock wave evolution from Al target under 355-nm laser ablation 下载免费PDF全文
The propagation of a plasma shock wave generated from an Al target surface ablated by a nanosecond Nd:YAG laser operating at 355 nm in air is investigated at the different focusing positions of the laser beam by using a time-resolved shadowgraph imaging technique. The results show that in the case of a target surface set at the off-focus position, the condition of the focal point behind or in front of the target surface greatly influences the evolution of an Al plasma shock wave, and an ionization channel forms in the case of the focal point set in front of the target surface. Moreover, it is found that the shadowgraph with the evolution time around 100 ns shows that a protrusion appears at the front tip of the shock wave if the focal point is at the target surface. In addition, the calculated results of the expanding velocity of the shock wave front, the mass density, and pressure just behind the shock wave front are presented based on the shadowgraphs. 相似文献
14.
报道在星光激光器上进行的X光辐射驱动(间接驱动)和激光直接驱动的冲击波实验。实验观察到了铝背冲击波发光信息。结果表明,间接驱动比直接驱动的冲击波平面性好。 相似文献
15.
16.
采用YLSS-M60U型高能Nd:YAG激光器,对发动机高压涡轮叶片材料K403/K3铸造高温合金试片进行激光冲击强化处理,强化工艺参数为:激光能量3J,光斑直径2.6mm,脉宽20ns,波长1064nm,吸收保护层为铝箔,约束层为水,搭接率50%,冲击3次。强化后,在420MPa应力水平下进行了室温高周振动疲劳测试,并进行了扫描电镜观察和X射线衍射仪物相分析。研究结果表明:激光冲击强化后,试片疲劳寿命是原始状态试片寿命的2.4倍,激光冲击强化的强冲击波作用使金属发生高应变率塑性变形,以及随之产生的较大较深残余压应力,是金属疲劳性能提高的主要原因。 相似文献
17.
18.
A. H. Guenther W. K. Pendleton C. Smith C. H. Skeen S. Zivi 《Optics & Laser Technology》1973,5(1):20-23
Air breakdown at pressures of 300 and 753 torr was produced by a 28J, 40 ns FWHM neodymium glass laser focused with a 100 mm focal length lens. The breakdown region was observed by recording infinite fringe, interferometric, diffuse holograms with a single-mode ruby laser of 100 ns FWHM pulse length. The two lasers were synchronized to examine the time region from < 1–38 μs after initiation. Shock wave velocities of about Mach 2 were typical at these times and the shock front was virtually spherical. The R-t diagram was found to be in excellent agreement with the weak spherical blast wave theory of Sakurai. The radial density profile of the shock wave was determined by an Abel inversion of the fringe pattern. Both the R-t function and the density profile were calculated using a one-dimensional, hydrodynamic model and good agreement was obtained. 相似文献
19.
在激光惯性约束聚变研究中不对黑腔和靶丸做额外处理的条件下,靶丸的早期驱动对称性一直缺少直观的观测手段.介绍了基于神光III原型装置发展的双轴任意反射面速度干涉仪技术及相应的实验结果.通过在靶丸内部安装小反射镜的方式,获得靶丸赤道及极区的冲击波速度历程.根据材料的反射率及其受X射线的影响程度,确定Al为现阶段反射镜的合适材料.对汇聚几何效应下的数据判读问题进行了分析,发现靶装配精度对该技术的影响很大.通过实验完成了双轴VISAR诊断技术的探索,可为进一步发展双轴速度干涉仪和多轴速度干涉仪的工作提供参考. 相似文献