Abstract Laser induced breakdown spectroscopy (LIBS) enables quantitative measurements of the equivalence ratio in flames, spray and gas jets. Although there are always considerable temperature differences between the calibrations and the LIBS measurements in flames and fuel jets, the temperature effects on LIBS were rarely mentioned and not corrected in the previous LIBS measurements. In this study, a novel method to simultaneously measure the equivalence ratio and the gas temperature by LIBS in a single laser shot is proposed. This method can correct the temperature effects based on the linear correlation between the peak intensity ratio (PIR) of atomic lines and the gas temperature. The PIR of H656/N746 and the full width at half maximum (FWHM) of H656 are employed to establish calibration curves with the equivalence ratio and the gas temperature, respectively, and both of calibrations show high coefficients of determination (R2). Then, the measurement accuracy and precision of the proposed method are discussed in detail. The total uncertainties in measurements of equivalence ratio and gas temperature are estimated by 5.6% and 5.8%, respectively. Finally, the simultaneous measurements of equivalence ratios and gas temperatures in methane jets at different positions and at different injection pressures are conducted. The comparison of equivalence ratios before and after correction of the temperature effects indicates that the accuracy of the fuel concentration measurements by LIBS would be remarkably degraded if the temperature variations were neglected.

中文翻译：

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通过 LIBS 同时测量气体射流中的燃料浓度和温度

摘要 激光诱导击穿光谱 (LIBS) 能够定量测量火焰、喷雾和气体射流的当量比。尽管火焰和燃料喷射中的校准和 LIBS 测量之间总是存在相当大的温度差异，但温度对 LIBS 的影响很少被提及，并且在之前的 LIBS 测量中没有得到纠正。在这项研究中，提出了一种通过 LIBS 在单次激光发射中同时测量当量比和气体温度的新方法。该方法可以基于原子线峰值强度比（PIR）与气体温度之间的线性相关性来校正温度效应。H656/N746 的 PIR 和 H656 的半峰全宽 (FWHM) 分别用于建立与当量比和气体温度的校准曲线，并且两种校准都显示出较高的决定系数 (R2)。然后，详细讨论了所提出方法的测量精度和精密度。当量比和气体温度测量的总不确定度分别估计为 5.6% 和 5.8%。最后，同时测量了不同位置和不同注入压力下甲烷射流的当量比和气体温度。