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

本学年，我们在东京大学、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对风洞中产生的高焓羽流进行了光谱测量。结果总结如下：1)通过计算机层析重建实现了弧喷氩羽的三维性质测定。2)为了获得高温空气羽流的信息，我们在777.19 nm波长处获取了原子氧吸收谱线，成功测量了原子氧的平动温度和激发态原子氧的数密度。从测量的三维分布上，明确了氧气向氮气扩散混合的过程，并且由于这一过程，发现收缩型弧形风洞产生的羽流的解离程度低于期望值。3)在重复放电感应加热风洞中，成功地测量了高温纯氧流中原子氧的温度分布和原子氧数密度分布。4)利用激光吸收光谱技术成功地诊断了激光诱导荧光或发射光谱测量中比较困难的光学厚羽。（最大吸收率达到97%）5)我们的激光诊断系统的便携性和广泛使用性已经通过运输和应用于位于名古屋，东京和斯图加特，德国的风洞。6)为了将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.