基于TDLAS测量HBr化学激光器气体温度

利用可调谐二极管激光吸收光谱技术（TDLAS），基于吸收光谱的多普勒展宽原理，对D2/NF3燃烧驱动的HBr化学激光器，进行了光腔和扩压段的气体温度测量实验研究。为了有效地测量TDLAS吸收光谱，选用了主气流中吸收系数较大的HF分子（2-0）振动谱带的R2谱线作为研究对象。实验中利用一台中心波长1 273 nm的分布反馈式（DFB）二极管激光器，搭建了一套基于直接吸收法TDLAS的HBr化学激光器气体温度测量系统。通过对HF分子的吸收谱线进行Voigt线型拟合，获得了多普勒展宽宽度，从而给出了光腔和扩压段气体温度。在进行时域频域变换时，使用了一台自由光谱范围（FSR）为1.5 GHz的F-P标准具用于频率校准。实验测量结果表明，光腔温度约为280 K，扩压段温度约为400 K。实验过程中的碰撞展宽和多普勒展宽的比值小于0.1，表明多普勒展宽为主，能够方便地用HF吸收光谱的展宽来监测光腔和扩压段的气体温度。

Measurements of gas temperature in HBr chemical lasers by TDLAS technique

Based on the Doppler broadening principle of absorption spectrum, the gas temperature measurement experiments of the optical cavity and the diffuser section were carried out on the D2/NF3 combustion-driven HBr chemical laser using the tunable diode laser absorption spectroscopy (TDLAS) technique. In order to effectively measure the TDLAS absorption spectrum, the R2 line of the HF molecular (2-0) vibrational band with a large absorption coefficient in the main gas flow was selected. In the experiment, a distributed feedback (DFB) diode laser with a center wavelength of 1 273 nm was used to build a HBr chemical laser gas temperature measurement system based on direct absorption TDLAS technique. By fitting the Voigt line shape to the absorption line of the HF molecule, the Doppler broadening width was obtained, and the gas temperatures of the optical cavity and the diffusing section were given. In the time domain frequency domain conversion, an F-P etalon with a free spectral range (FSR) of 1.5 GHz was used for frequency calibration. Experimental measurement results show that the temperature of the optical cavity is about 280 K and the temperature of the diffusing section is about 400 K. The ratio of collision broadening and Doppler broadening during the experiment is less than 0.1, indicating that the Doppler broadening is dominant, and the gas temperature of the optical cavity and the diffusing section can be conveniently monitored by the broadening of the HF absorption spectrum.