超短脉冲强激光产生的等离子体X射线发射光谱的实验研究
文献类型：学位论文
| 作者 | 覃岭 |
| 学位类别 | 硕士 |
| 答辩日期 | 1999 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 张正泉 |
| 关键词 | 超短强激光脉冲 激光等离子体 X射线源 等离子体诊断 喷气靶 微毛细管靶 |
| 中文摘要 | 近年来，超短强激光技术得到了飞速的发展，激光脉冲的持续时间已经进入飞秒(10~(-15)S)范围，聚焦后场强已经达到甚至超过了氢原子内部的库仑场强，从而开辟了强场作用下物质形态研究的新领域。激光等离子体X射线源由于在物理、化学、生物医学中潜在的巨大应用，得到了人们的普遍关注。获得超短、高亮度的X射线源是超短脉冲强激光与物质作用研究的主要目标。本工作主要对飞秒激光脉冲与固体靶、喷气靶、微毛细管靶相互作用进行了初步的实验研究，获得了不同物质的X射线源。并对激光与靶相互作用过程下等离子体产生的机制以及特性进行了初步的实验研究。本论文具体包括：1．研究了不同脉宽的激光脉冲辐照下固体平面靶等离子体发射光谱的不同特性。相比纳秒激光情况，飞秒激光脉冲下等离子体的发射光谱向短波方向移动；飞秒激光脉冲作用下等离子体的温度(500eV)，电子密度(3 * 10~(21)/cm~3)比纳秒情况(100eV, 2 * 10~(20)/cm~3)下要高；对铝等离子体X射线的空间发射特性分析发现，飞秒激光产生的等离子体长度短而且X射线的强区更靠近靶面。另外，铜平面靶也获得了高产额光谱。2．进行了强激光作用下气体靶X射线辐射特性的实验研究。利用带差分泵浦系统的高效高分辨率软X射线大面积透射光栅光谱仪，测得了超短强激光脉冲辐照下氩气体靶在12nm-35nm范围内的X射线发射光谱。实验发现，X射线发射强度随喷气气压的增加而增强。3．在国内首次进行了超短强激光与微毛细管相互作用的研究。利用45fs的钛宝石激光，研究了激光能量、微毛细管的长度、微毛细管的内径等参数对软X射线发射谱的影响。实验结果发现微毛细管对激光有较好的引导作用，微毛细管的长度增加或内径减少时，X射线的发射强度增强，对后续的X射线激光的实验研究有一定的启发意义。作为X射线光源，微毛细管靶较平面靶有更高的亮度、更好的方向性，更有实用价值。 |
| 英文摘要 | In recent years, great progress has been made in the development of ultrashort, intense laser system. The laser duration now can be on the order of femtosecond, and the laser pulse field strength has reached or been higher than the coulombic field binding the ground state electron in the hydrogen atom. This opens a new research area of the laser-matter-interaction. The study of the laser-plasma x-ray source is particularly interesting, since it can obtain picosecond time resolution which is required in many research fields such as molecular science and medicine. To generate ultrashort, high bright x-ray sources is the main goal in the area. The work of this dissertation is about experimental study on the femtosecond laser pulses interaction with the slab target, the gas jet target and the microcapillary target. The x-ray sources from different matter is demonstrated. 1. We investigate the characteristics of x-ray emission from slab target irradiated by 45fs and 6ns pulse lasers respectively. It shows that under fs laser, the x-ray emission is dominantly from K shell, the aluminum plasmas temperature is about 500eV and the electron density is about 3 * 10~(21)/cm~3, while in the ns pulse laser situation, is L shell, 100eV and 2 * 10~(20)/cm~3 respectively. The spatial distributions are also compared simply. 2. Using a high efficiency, high resolution transmission grating combined with a differential pump system, we studied the spectroscopy characteristics of Ar plasmas produced by the ultrashort pulse intense laser. Increment of the emission spectra among 12-35nm with the chamber gas pressure were observed. 3. The characteristics of x-ray emission from glass capillary target irradiated by ultrashort intense laser pulses is investigated. Soft x-ray spectra at different laser energies, with different capillary lengths and radii were measured. X-ray emission intensity is increased obviously when the length is increased, which proves the guide effect of the capillary. An advantage of the x-ray source using this target is its high brightness and good direction. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16638]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 覃岭. 超短脉冲强激光产生的等离子体X射线发射光谱的实验研究[D]. 中国科学院上海光学精密机械研究所. 1999. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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