激光诱导击穿光谱应用以及双色激光与气体作用产生太赫兹辐射的研究
发布时间：2018-07-23 15:08
【摘要】：本硕士论文包含两部分的工作,其中第一部分是激光诱导击穿光谱(LIBS)技术在液体样品方面的技术发展和应用进展综述,另一部分是双色激光与气体作用产生太赫兹辐射的理论模拟研究。LIBS技术经过50年的发展已经成为进行元素检测的重要工具,被广泛应用于固态、液态、气态样本中。与LIBS技术应用于固态样本相比,由于液体样本中LIBS光谱强度较弱,所以分析效果不佳。但是传统的液体样本元素的检测方法仅局限于实验室研究,而LIBS可远程、实时、在线进行元素分析,具有极大的吸引力。故众多研究者致力于液体LIBS信号的优化研究。本文重点介绍了液体LIBS的特性、常用的取样方法、定标方法,以及在工业、日常生活、环境检测、生物医药等诸多方面的重要应用。第二部分是关于双色激光与气体作用产生太赫兹辐射的理论模拟,主要是探讨这种条件下太赫兹辐射产生的物理机制。太赫兹(THz)辐射通常是指频率介于0.1-10THz的电磁辐射,在电磁波谱中处于高频微波和红外光之间。目前强激光与气体靶作用是产生高功率太赫兹辐射的一个重要途径。本文利用光电离电流模型研究了800nm激光和它的半频光1600nm激光与气体作用产生强太赫兹辐射的过程。计算表明:(1)不同的气体种类、双色激光相位差、激光的振幅均会影响离化电流的大小,可以通过各种参数对太赫兹振幅强度的影响进行优化。(2)通过改变双色激光偏振方向的夹角,发现小于72度时产生离化电流的方向开始主要受基频光偏振方向的影响,大于72度时主要受半频光的偏振方向影响。
[Abstract]:This thesis consists of two parts. The first part is a review of the development and application of laser-induced breakdown spectroscopy (LIBS) in liquid samples. The other part is the theoretical simulation of terahertz radiation produced by two-color laser and gas. After 50 years of development, LIBS technology has become an important tool for element detection, and has been widely used in solid, liquid and gaseous samples. Compared with the application of LIBS technique in solid samples, the analysis effect is not good because of the weak spectral intensity of LIBS in liquid samples. However, the traditional detection methods of liquid sample elements are limited to laboratory research, and LIBS can be used for element analysis remotely, in real time and online, so it has great attraction. Therefore, many researchers focus on the optimization of liquid LIBS signals. In this paper, the characteristics of liquid LIBS, sampling methods, calibration methods, and important applications in industry, daily life, environmental detection, biomedicine and so on are introduced. The second part is about the theoretical simulation of terahertz radiation produced by the interaction of two-color laser and gas, which mainly discusses the physical mechanism of terahertz radiation under this condition. Terahertz (THz) radiation usually refers to electromagnetic radiation with a frequency between 0.1-10THz and high frequency microwave and infrared light in the electromagnetic spectrum. At present, the interaction between intense laser and gas target is an important way to produce high power terahertz radiation. In this paper, the photoionization current model is used to study the process of strong terahertz radiation produced by 800nm laser and its half-frequency optical 1600nm laser interacting with gas. The results show that: (1) for different gas types, the phase difference of two-color laser, the amplitude of laser will affect the magnitude of ionization current. The influence of various parameters on the amplitude intensity of terahertz can be optimized. (2) by changing the angle of polarization direction of two-color laser, it is found that the direction in which the ionization current is produced when less than 72 degrees is mainly affected by the polarization direction of fundamental frequency light. The polarization direction of the half-frequency light is mainly affected when it is more than 72 degrees.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN24
[Abstract]:This thesis consists of two parts. The first part is a review of the development and application of laser-induced breakdown spectroscopy (LIBS) in liquid samples. The other part is the theoretical simulation of terahertz radiation produced by two-color laser and gas. After 50 years of development, LIBS technology has become an important tool for element detection, and has been widely used in solid, liquid and gaseous samples. Compared with the application of LIBS technique in solid samples, the analysis effect is not good because of the weak spectral intensity of LIBS in liquid samples. However, the traditional detection methods of liquid sample elements are limited to laboratory research, and LIBS can be used for element analysis remotely, in real time and online, so it has great attraction. Therefore, many researchers focus on the optimization of liquid LIBS signals. In this paper, the characteristics of liquid LIBS, sampling methods, calibration methods, and important applications in industry, daily life, environmental detection, biomedicine and so on are introduced. The second part is about the theoretical simulation of terahertz radiation produced by the interaction of two-color laser and gas, which mainly discusses the physical mechanism of terahertz radiation under this condition. Terahertz (THz) radiation usually refers to electromagnetic radiation with a frequency between 0.1-10THz and high frequency microwave and infrared light in the electromagnetic spectrum. At present, the interaction between intense laser and gas target is an important way to produce high power terahertz radiation. In this paper, the photoionization current model is used to study the process of strong terahertz radiation produced by 800nm laser and its half-frequency optical 1600nm laser interacting with gas. The results show that: (1) for different gas types, the phase difference of two-color laser, the amplitude of laser will affect the magnitude of ionization current. The influence of various parameters on the amplitude intensity of terahertz can be optimized. (2) by changing the angle of polarization direction of two-color laser, it is found that the direction in which the ionization current is produced when less than 72 degrees is mainly affected by the polarization direction of fundamental frequency light. The polarization direction of the half-frequency light is mainly affected when it is more than 72 degrees.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN24
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