燃烧驱动氟化氢化学激光体系中有一些关键基态物种(如DF等)可用于表征燃烧室工作状态, 为了控制HF振动激发态的弛豫过程还需要加入少量的碰撞伴侣物种(如SF6、NH3、H2O等）, 另一些关键物种(如NF(a)等)则可能会与HF振动激发态发生传能过程, 然而不幸的是这些物种的吸收较小。为了利用吸收光谱对这些弱吸收的关键基态物种进行研究, 建立了基于离轴式布局的腔增强吸收光谱装置, 该装置由光源部分、谐振腔部分和光电接收部分组成, 其中谐振腔部分处于真空仓内。为了验证该装置的性能, 测量了痕量氨气和水汽的吸收光谱。实验结果表明: 该装置的等噪声吸收系数达到了1.6×10-8 cm-1, 表明该装置可以用于氟化氢化学激光器中关键痕量物种的测量诊断工作。

Combustion driven chemical laser system has a number of key species in ground states such as DF molecules which can characterize the performance of the combustor of chemical lasers. Additives such as SF6, NH3 and H2O may be added into chemical lasers as collisional particles in order to control the relaxation processes of vibrational-rotational excited states of hydrogen fluoride molecules. There are also some key intermediate species such as NF(a) which could interact with vibrational-rotataional excited states of hydrogen fluoride molecules via near-resonant energy transfer processes. However, the absorption coefficients of these key species are generally very small. In order to obtain the absorption spectrum of the ground state of these key species, an off-axis cavity enhanced absorption spectroscopy apparatus was established. The apparatus consisted of the light source, the optical resonator and the photoelectric receiver, wherein the resonator was built within a vacuum chamber. In order to verify the performance of the device, the absorption spectra of trace amounts of ammonia and water vapor were measured. The results showed that the noise equivalent absorption coefficient of the device reached 1.6×10-8 cm-1. The experiment results show that the cavity enhanced absorption spectrometer can be used to obtain the number densities of those key species in HF chemical lasers.