激光诱导Ti等离子体特性的实验研究

发布时间：2018-09-02 07:35

【摘要】：应用脉冲激光冲击靶材,使其产生等离子体,然后对等离子体辐射的光谱进行检测分析从而获得靶材的相关信息,这就是激光诱导等离子体光谱技术(即LIBS)的应用原理。由于LIBS具有对检测样品的形态无要求且对样品几乎无损伤,检测精度高,范围大,操作方便等优点,因此其广泛运用于各学科和领域。金属Ti具有质轻、比强度大、耐腐蚀性等优点,广泛应用于航空业,造船业,机械制造和通讯器材的方面。研究Ti等离子体的性质可以让我们对金属Ti有更深刻的了解和更好的运用,本文利用LIBS技术对Ti靶进行冲击,检测并分析了Ti等离子体的性质,全文的主要研究工作如下:第一部分:阐述了等离子体及激光诱导等离子体的概念、性质、产生的原因以及分类,对等离子体谱线的展宽进行了分析。详细描述了光谱定量分析两种常用方法,内标法和标准加入法。第二部分:计算并分析了Ti等离子体在激光能量为180mJ、230mJ和280mJ,延迟时间为0~500ns情况下的等离子体电子温度。室温、常压下,利用Nd:YAG脉冲激光器产生的波长为1064nm的脉冲激光冲击Ti靶,改变激光器的能量和延时器的延迟时间,得到Ti等离子体光谱,分析谱线可以得到多条TiI和TiII离子谱线,证明在该实验条件下,激光能量足够Ti靶电离,利用Saha-Boltzmann法计算并分析Ti等离子体电子温度,实验结果表明:延迟时间100ns,激光能量为230mJ时,等离子体电子温度T=9374K。延迟时间为0~150ns时,电子温度快速下降,激光能量为280mJ时,电子温度下降了约5500K,激光能量230mJ和180mJ时,电子温度分别下降了5000K和5100K。延迟时间为150ns~250ns时,三种等离子体的电子温度都缓慢上升,其中180mJ激光能量下的电子温度上升速率较快。其电子温度上升了近600K,230mJ和280mJ激光能量下,电子温度分别上升了370K和480K。延迟时间250ns~500ns时,三种激光能量下的等离子体电子温度都缓慢下降,其中230mJ激光能量下的等离子体的电子温度由8253K缓慢下降到6880K,180mJ和280mJ激光能量下,电子温度分别下降了1150K和1700K。第三部分:计算并分析了Ti等离子体在激光能量为180mJ、230mJ和230mJ,延迟时间为0~500ns情况下电子密度的时间演化规律。根据第二部分实验中得到的光谱图,选取激光能量为230mJ,延迟时间为100ns时,谱线TiII375.95nm附近的曲线进行Lorentz曲线拟合,得到拟合后谱线半高宽为0.108nm,根据斯塔克展宽法计算得到电子密度为1.49×1016cm-3。对三种激光能量下的等离子体电子密度的时间演化规律分析发现:在延迟时间0~150ns内,随着等离子体向外快速膨胀,空间逐渐增大,等离子体电子密度急速下降,其中280mJ激光能量下的电子密度下降速率最快,电子密度从4.1×1016cm-3下降到0.75×1016cm-3。延迟时间为150ns~250ns时,三种激光能量下的等离子体电子密度都缓慢上升。激光能量为280mJ时,电子密度约增加了0.24×1016cm-3,230m J和180mJ时,电子密度分别增加了0.15×1016cm-3和0.1×1016cm-3。延迟时间为250ns~500ns内,该阶段为缓慢下降阶段,,三种激光能量下的等离子体密度都逐渐减小。激光能量为180mJ和230mJ情况下,电子密度均下降到0.62×1016cm-3。
[Abstract]:The application principle of laser-induced plasma spectroscopy (LIBS) is that the laser-induced plasma spectroscopy (LIBS) can be used to detect and analyze the radiation spectrum of the plasma produced by the pulsed laser impacting the target. Ti is widely used in various disciplines and fields because of its high precision, wide range and convenient operation. Ti metal has the advantages of light weight, high specific strength and corrosion resistance. It is widely used in aviation, shipbuilding, mechanical manufacturing and communication equipment. Studying the properties of Ti plasma can make us have a better understanding of Ti metal. In this paper, we use LIBS technology to impact the Ti target, detect and analyze the properties of Ti plasma. The main research work of this paper is as follows: Part 1: The concepts, properties, causes and classification of plasma and laser-induced plasma are expounded, and the broadening of plasma spectrum is analyzed. The second part: The electron temperature of Ti plasma with laser energy of 180 mJ, 230 mJ and 280 mJ and delay time of 0~500 ns is calculated and analyzed. The spectrum of Ti plasma can be obtained by changing the energy of laser and the delay time of the delayer. Several TiI and TiII ion lines can be obtained by analyzing the spectrum lines. It is proved that the laser energy is enough for the ionization of Ti target under this experimental condition. The electron temperature of Ti plasma is calculated and analyzed by Saha-Boltzmann method. The experimental results show that the delay time is 100ns, and the laser can be used to analyze the electron temperature of Ti plasma. When the laser energy is 280mJ, the electron temperature decreases about 5500K. When the laser energy is 230mJ and 180 mJ, the electron temperature decreases by 5000K and 5100K respectively. When the delay time is 150ns~250ns, the electron temperature of the three plasmas decreases rapidly. When the electron temperature rises by about 600K, 230mJ and 280mJ laser energy, the electron temperature rises by 370K and 480K respectively. When the delay time is 250ns~500ns, the electron temperature of the plasma decreases slowly, and the plasma at 230mJ laser energy decreases slowly. The electron temperature decreases slowly from 8253K to 6880K, 180mJ and 280mJ, respectively. Part 3: The time evolution of electron density in Ti plasma with laser energy of 180 mJ, 230mJ and 230mJ and delay time of 0 ~ 500ns is calculated and analyzed. The Lorentz curve was fitted to the curve near TiII375.95 nm when the laser energy was 230 mJ and the delay time was 100 ns. The half-width of the fitted line was 0.108 nm. According to the Stark broadening method, the time evolution law of the plasma electron density under three laser energies was obtained. It is found that the electron density decreases sharply with the rapid expansion of the plasma in the range of 0-150 ns. The electron density decreases fastest at 280 mJ laser energy, and decreases from 4.1 1016 cm-3 to 0.75 When the laser energy is 280 mJ, the electron density increases by 0.24 *1016 cm-3, 230 mJ and 180 mJ, respectively, the electron density increases by 0.15 *1016 cm-3 and 0.1 *1016 cm-3. The delay time is between 250 ns and 500 ns, and the plasma density decreases gradually under the three laser energies. When the laser energy is 180mJ and 230mJ, the electron density decreases to 0.62 * 1016cm-3.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.23;TG665

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