發(fā)布時間：2018-09-02 07:35

【摘要】：應用脈沖激光沖擊靶材,使其產(chǎn)生等離子體,然后對等離子體輻射的光譜進行檢測分析從而獲得靶材的相關信息,這就是激光誘導等離子體光譜技術(即LIBS)的應用原理。由于LIBS具有對檢測樣品的形態(tài)無要求且對樣品幾乎無損傷,檢測精度高,范圍大,操作方便等優(yōu)點,因此其廣泛運用于各學科和領域。金屬Ti具有質輕、比強度大、耐腐蝕性等優(yōu)點,廣泛應用于航空業(yè),造船業(yè),機械制造和通訊器材的方面。研究Ti等離子體的性質可以讓我們對金屬Ti有更深刻的了解和更好的運用,本文利用LIBS技術對Ti靶進行沖擊,檢測并分析了Ti等離子體的性質,全文的主要研究工作如下:第一部分:闡述了等離子體及激光誘導等離子體的概念、性質、產(chǎn)生的原因以及分類,對等離子體譜線的展寬進行了分析。詳細描述了光譜定量分析兩種常用方法,內(nèi)標法和標準加入法。第二部分:計算并分析了Ti等離子體在激光能量為180mJ、230mJ和280mJ,延遲時間為0~500ns情況下的等離子體電子溫度。室溫、常壓下,利用Nd:YAG脈沖激光器產(chǎn)生的波長為1064nm的脈沖激光沖擊Ti靶,改變激光器的能量和延時器的延遲時間,得到Ti等離子體光譜,分析譜線可以得到多條TiI和TiII離子譜線,證明在該實驗條件下,激光能量足夠Ti靶電離,利用Saha-Boltzmann法計算并分析Ti等離子體電子溫度,實驗結果表明:延遲時間100ns,激光能量為230mJ時,等離子體電子溫度T=9374K。延遲時間為0~150ns時,電子溫度快速下降,激光能量為280mJ時,電子溫度下降了約5500K,激光能量230mJ和180mJ時,電子溫度分別下降了5000K和5100K。延遲時間為150ns~250ns時,三種等離子體的電子溫度都緩慢上升,其中180mJ激光能量下的電子溫度上升速率較快。其電子溫度上升了近600K,230mJ和280mJ激光能量下,電子溫度分別上升了370K和480K。延遲時間250ns~500ns時,三種激光能量下的等離子體電子溫度都緩慢下降,其中230mJ激光能量下的等離子體的電子溫度由8253K緩慢下降到6880K,180mJ和280mJ激光能量下,電子溫度分別下降了1150K和1700K。第三部分:計算并分析了Ti等離子體在激光能量為180mJ、230mJ和230mJ,延遲時間為0~500ns情況下電子密度的時間演化規(guī)律。根據(jù)第二部分實驗中得到的光譜圖,選取激光能量為230mJ,延遲時間為100ns時,譜線TiII375.95nm附近的曲線進行Lorentz曲線擬合,得到擬合后譜線半高寬為0.108nm,根據(jù)斯塔克展寬法計算得到電子密度為1.49×1016cm-3。對三種激光能量下的等離子體電子密度的時間演化規(guī)律分析發(fā)現(xiàn):在延遲時間0~150ns內(nèi),隨著等離子體向外快速膨脹,空間逐漸增大,等離子體電子密度急速下降,其中280mJ激光能量下的電子密度下降速率最快,電子密度從4.1×1016cm-3下降到0.75×1016cm-3。延遲時間為150ns~250ns時,三種激光能量下的等離子體電子密度都緩慢上升。激光能量為280mJ時,電子密度約增加了0.24×1016cm-3,230m J和180mJ時,電子密度分別增加了0.15×1016cm-3和0.1×1016cm-3。延遲時間為250ns~500ns內(nèi),該階段為緩慢下降階段,,三種激光能量下的等離子體密度都逐漸減小。激光能量為180mJ和230mJ情況下,電子密度均下降到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.
【學位授予單位】：江蘇大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG146.23;TG665

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