激光感生击穿煤质实验中延迟时间的研究

激光感生击穿光谱是一种新型的物质元素分析技术，可望用于煤质分析。其信号取样的延迟时间是光谱检测中的一个重要参数。文章搭建了一套实验台架，选取江西萍乡煤、山西西山煤和贵州平寨煤为代表性煤样进行了研究。给出了三种煤样240～250和275～290 nm波段的光谱图，参考NIST数据库，定性分析了C，Mg和Si元素的特征谱线。通过计算，得出了特征谱线信噪比的时间演化曲线。结果表明，随着延迟时间的增加，信噪比都要经历一个由小到大，随后又减小的过程。随煤样不同、元素不同、谱线不同，信噪比的时间演化特性均可能存在不同。根据信噪比最高的原则，得出了三种煤样中各特征谱线的最佳延迟时间，并分析了煤样特性、元素特性和谱线特性对最佳延迟时间的影响

Investigation on the Delay Time of Coal Experiment by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy is a new technology of elementary analysis,and it will be used in coal analysis.The delay time of signal is an important parameter of spectral analysis.A LIBS system was set up and three kinds of coal(Jiangxipingxiang coal,Shanxixishan coal and Guizhoupingzhai coal)were chosen for this investigation.The spectra in the range of 240 to 250 nm and 275 to 290 nm of the each three coal samples are shown and they record several spectral lines of components such as C,Mg and Si according to the NIST database.The temporal evolution of SNR of spectral line was obtained,and the value of SNR increased with the time delay,then decayed.The temporal evolution of SNR was different as the coal,element and spectral line differs.Finally,optimum delay time of each spectral lines of elements in the coal samples was calculated according to the biggest value of signal-to-noise ratio,and the relation between the characteristic of coal,element,spectral line and the optimum delay time was analyzed.