不同能量水下激光诱导等离子体的轴向辐射分布特性研究

发布时间：2018-04-28 00:59

本文选题：LIBS + 激光能量　；参考：《光谱学与光谱分析》2016年04期

【摘要】：激光诱导击穿光谱(LIBS)技术作为一项新兴的水下原位探测技术,备受海洋探测技术领域的关注。将这项技术推向实用化的关键之一是改善LIBS的远程探测能力,因此需要采用超击穿阈值的高能量探测激光。为观察超击穿阈值情况下的等离子体辐射和动态击穿特性,采用图像与光谱相结合的方法,以KCl溶液为样品进行了系列实验研究。通过对1~20mJ不同能量激发下的等离子体图像分析,获得了不同激发条件下总辐射的轴向跨度和最亮点位置信息。随激光脉冲能量增大,等离子体长度增加,从1mJ时的0.49mm增加到20mJ时的1.83mm,同时辐射最亮点位置向激光入射方向移动了0.79mm。结合光谱探测分析,得出等离子体特征辐射的轴向空间分布也对激光能量有明显的依赖性。虽然不同能量下谱线强度呈相似的轴向空间分布,但钾原子辐射最强处的位置和相应强度均随能量变化,在5mJ激发下获得最佳辐射强度。实验结果表明,为满足远程LIBS应用需求,提高激光能量时应考虑其对原子辐射的影响。还对不同能量下的谱线的半高宽和信背比进行了观测分析。
[Abstract]:Laser induced breakdown spectroscopy (LIBS), as a new in situ underwater detection technology, has attracted much attention in the field of ocean exploration. One of the keys to the practical application of this technique is to improve the remote detection capability of LIBS, so it is necessary to use high-energy detection laser with overbreakdown threshold. In order to observe the radiation and dynamic breakdown characteristics of plasma at overbreakdown threshold, a series of experiments were carried out using KCl solution as sample by combining image and spectrum. By analyzing the plasma images excited by 1~20mJ with different energy, the axial span and the location of the highlight of the total radiation under different excitation conditions are obtained. With the increase of laser pulse energy, the length of plasma increases from 0.49mm at 1mJ to 1.83 mm at 20mJ, and the position of the luminescent spot moves 0.79 mm. to the direction of incident laser. Combined with spectral analysis, it is concluded that the axial spatial distribution of plasma characteristic radiation is also obviously dependent on laser energy. Although the intensity of the spectral line exhibits a similar axial spatial distribution at different energies, the position and the corresponding intensity of the strongest radiation of the potassium atom vary with the energy, and the optimum radiation intensity is obtained under the excitation of 5mJ. The experimental results show that the influence of laser energy on atomic radiation should be considered in order to meet the requirements of remote LIBS applications. The half-width and the signal-back ratio of the spectral lines at different energies are also observed and analyzed.
【作者单位】：中国海洋大学光学光电子实验室;
【基金】：国家自然科学基金项目(41376107)资助
【分类号】：O53;TN24

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