本文關鍵詞： 飛秒激光 光絲 閾值功率 光絲誘導非線性熒光光譜 燃燒診斷 脈沖寬度　出處：《吉林大學》2017年碩士論文　論文類型：學位論文

【摘要】：燃燒診斷為理解燃燒中復雜的化學反應過程以及提高燃燒過程能量轉換效率提供實驗依據。各種激光光譜診斷技術的發(fā)明,為燃燒診斷開創(chuàng)了新局面,其具有實時、非入侵性、高時空分辨率等優(yōu)點。本文驗證了利用飛秒激光成絲誘導非線性光譜的手段分析燃燒中間產物分布的可行性。在克爾自聚焦和等離子體散焦的平衡作用下,飛秒激光周期性重復聚焦和散焦過程,從而形成一條長長的等離子體通道,即光絲。飛秒激光光絲內部的超高場強足以誘導路徑上的分子、原子發(fā)生離化,并產生可用于鑒別母體分子的特征性指紋熒光,所以成絲手段具有僅使用單一光源對多種燃燒中間產物同時監(jiān)測的獨特能力。但激光參數,如脈寬等,對光絲誘導的熒光信號的影響目前尚不完全明確,本論文以光絲誘導非線性光譜技術為基礎,并重點研究了燃燒場中激光脈寬這一重要參數對飛秒激光成絲特性的影響,主要內容和結果如下:首先,我們利用飛秒激光在酒精火焰中成絲的辦法,同時得到了多種燃燒中間產物的熒光光譜,并觀測了脈寬對光絲誘導的酒精火焰熒光光譜的影響。實驗中波長為800nm的飛秒激光經透鏡聚焦至酒精燈陣列火焰中成絲,在側向收集熒光信號。通過調整壓縮機的電機位置來改變脈寬,觀測各種燃燒中間產物熒光光譜變化情況。我們發(fā)現隨著脈寬的增加,光譜中的各信號峰值強度隨之減弱。其次,我們還觀測了脈寬對飛秒激光在火焰中成絲閾值功率的影響。實驗中我們利用觀測焦點移動的辦法成功測量了飛秒激光在酒精火焰中成絲的閾值功率,并改變激光脈寬觀測成絲閾值功率的變化情況。我們發(fā)現,在火焰環(huán)境下飛秒激光成絲閾值功率隨著脈寬增加而逐漸減小,這個規(guī)律和空氣中得到的結果相類似。
[Abstract]:Combustion diagnosis provides experimental basis for understanding the complex chemical reaction process and improving the efficiency of energy conversion in combustion process. The invention of various laser spectrum diagnostic techniques opens up a new prospect for combustion diagnosis. It is real-time, non-invasive. In this paper, the feasibility of using femtosecond laser filament-induced nonlinear spectra to analyze the distribution of combustion intermediates is verified. Under the equilibrium of Kerr autofocus and plasma defocusing. The femtosecond laser periodically repeats the focusing and defocusing process, thus forming a long plasma channel, I. E. the ultra-high field intensity inside the femtosecond laser fiber is enough to induce molecular ionization in the path. Because of the characteristic fingerprint fluorescence which can be used to identify the parent molecule, the filament forming method has a unique ability to monitor multiple combustion intermediates simultaneously using only a single light source. However, laser parameters, such as pulse width, etc. At present, the effect on the fluorescence signal induced by optical filament is not completely clear. This paper is based on the technology of optical filament induced nonlinear spectroscopy. The influence of laser pulse width on the filamentary characteristics of femtosecond laser is studied. The main contents and results are as follows: firstly, we use femtosecond laser to filamentate in alcohol flame. At the same time, the fluorescence spectra of various combustion intermediates were obtained. The effect of pulse width on the fluorescence spectra of alcohol flame induced by optical filament was observed. In the experiment, the femtosecond laser with wavelength of 800 nm was focused through lens into the flame of wine lamp array. Fluorescence signals were collected in the lateral direction. The pulse width was changed by adjusting the motor position of the compressor, and the fluorescence spectra of various combustion intermediates were observed. We found that the pulse width increased with the increase of the pulse width. The peak intensity of each signal in the spectrum decreases. Secondly. We also observed the effect of pulse width on the threshold power of femtosecond laser filamentations in flame. We successfully measured the threshold power of femtosecond laser in alcohol flame by moving the observed focus. We find that the femtosecond laser filamentary threshold power decreases with the increase of the pulse width. This pattern is similar to that obtained in the air.
【學位授予單位】：吉林大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O643.21;TN249

【參考文獻】

相關期刊論文 前4條

1 楊栩;;淺析大氣污染與可持續(xù)發(fā)展[J];信息化建設;2015年10期

2 倪潔蕾;程亞;;飛秒激光成絲若干新效應研究進展[J];深圳大學學報(理工版);2014年01期

3 高甫生;;霧霾天氣、環(huán)境與能源——暖通空調行業(yè)的對策[J];暖通空調;2013年09期

4 張淑娥,宋文妙;高階色散對光脈沖傳輸的影響[J];華北電力大學學報;2003年04期

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