傅里叶变换红外光谱技术测量甲烷气压的实验研究

Methane Pressure Detection Based on Fourier Transform Infrared Spectroscopy

烷烃类气体中的碳原子是碱金属激光器中碳粒沉积的唯一来源,因此对碱金属蒸气室内的烷烃气体气压进行高精度无干扰探测有助于定量分析碳粒沉积问题。采用傅里叶变换红外光谱技术,选择主峰右翼的吸收峰(3.369μm)作为特征峰,对甲烷气压进行了定量分析,并分析了蒸气室倾斜对测量精度的影响。实验结果表明,对纯甲烷以及甲烷和氦气配比1…3时的气体,该方法对甲烷气压的测量最大偏差分别为0.055kPa和0.057kPa;当蒸气室倾斜角度大于0.0035rad时,测量偏差将高于0.075%。该定量分析甲烷气压方法的测量精度满足碱金属激光器碳粒沉积问题表征的需求,将为碱金属激光器碳粒沉积机理研究提供参考。

Since the carbon atoms from the hydrocarbon gases are the unique resource of carbon deposition in alkali vapor laser, precise measurement for the gas pressure in a stand-off way will be helpful to depict the carbon contamination phenomenon quantitatively. Based on the Fourier transform infrared spectroscopy, a method for detecting the methane pressure is presented. In the method, the peak （3. 369 μm） on the right side of the main peak is chosen to be the characteristic peak. The effects of the alkali celt tilt on the accuracy are also researched. The experimental results show that the maximum deviations are 0. 055 kPa and 0. 057 kPa when only methane is in the cell or the volume ratio of methane and helium filled in the cell is 1：3. The deviations will be higher than 0. 075 % if the tilt angle is higher than 0.0035 rad. The measurement accuracy of the methane pressure can characterize the carbon contaminating problems, and provide a reference for investigating the mechanism of carbon contamination in the alkali lasers.