Development of the Diode-Laser Absorption Spectroscopy System for the Diagnostics of High-Temperature Flows.

在本学年，我们对东京大学、名古屋大学、日本超高温材料研究中心(名古屋)、国家航空航天实验室(Chofu)和德国斯图加特大学(University Of Stuttgart)的风洞中产生的高焓羽流进行了光谱测量。主要结果如下：1)利用计算机层析重建技术实现了对电弧喷气发动机气体羽流特性的三维测量。2)为了获得高温空气羽流的信息，我们在777.19 nm波长处获得了原子氧吸收谱线，并成功地测量了原子氧的平移温度和激发态原子氧数密度。3)在重复放电感应加热风洞中，我们成功地测量了高温纯氧气流中原子氧的温度和数密度分布。4)利用激光吸收光谱分析技术，成功地对激光诱导荧光或发射光谱测量困难的光学厚羽进行了诊断。(最大吸收达到97%)5)我们的激光诊断系统的便携性和广泛的用途已经通过运输和应用于位于东京名古屋和德国斯图加特的风洞而得到证明。6)为了未来系统性能的改进和地面数密度的测量，将其灵敏度提高几个数量级是必不可少的。

In this academic year, we conducted spectroscopic measurements on high-enthalpy plumes generated in the wind tunnels at the university of Tokyo, Nagoya university, the Japan ultra-high temperature material research center (Nagoya), the national aerospace laboratory (Chofu), and the university of Stuttgart (Germany). The results are summarized as follows.1) Three-dimensional determination of arcjet argon-plume properties was achieved by computer tomographic reconstruction.2) In order to get the information of high-temperature air plume, we accessed to the atomic oxygen absorption line at the wavelength of 777.19 nm and successfully measured the translational temperature and the number density of excited atomic oxygen. From the measured three-dimension distribution, the diffusive mixing process of oxygen gas into nitrogen gas was clarified, and owing to this process, the degree of dissociation in the plume generated by constrictor-type arc-wind tunnels was found lower than the expected value.3) In the repetitively discharging inductive-heating wind tunnel, we succeeded in measuring the profiles of temperature and number density of atomic oxygen in high-temperature pure-oxygen flows.4) Diagnosis of the optically thick plumes, which is quite difficult for the Laser Induced Florescence or Emission Spectroscopy measurements, has been successfully done using Laser absorption spectroscopy. (The maximum absorption reached at 97%)5) The portability and wide-usage of our laser diagnostic system has been demonstrated by transporting and applying it to the wind tunnels located at Nagoya, Tokyo and Stuttgart, Germany.6) For the future improvement of system performance and for the measurement of ground level number density, the increase in its sensitivity by several orders of magnitude would be essential.