Measurement of Rarefied Gas Flow by OPMS (Optical Pressure Measurement System)

研制了一种基于O_2猝灭发光原理的压敏涂料光学压力测量系统。该压敏涂料以pt -八烷基卟啉或酞菁为发光基团，o_2渗透性硅聚合物为基体。实验研究了在压力760 ~ 10^<-3> Torr和温度30 ~ 80℃范围内，氧气分压变化对发光强度的影响。用波长为390nm的紫外光照射涂漆样品，用CCD相机检测发光团发出的波长为650nm的荧光，并由PC机进行数据处理。实验结果如下：压力P下的荧光强度I与参考压力P_<ref>下的荧光强度I_<ref>的比值满足Stern-Volmer关系，<<数值公式>>考虑到涂料厚度的影响，对上述关系进行修正，得到<<数值公式>>，但是平方项的系数与线性项的系数相比很小。当P/P_<ref> < 0.1时，Stern-Volmer关系不满足。在此范围内，dI/dP较大，显示出对压力的高灵敏度。绝对荧光强度取决于温度。P/P_<ref>和P/P_<ref>之间的关系不依赖于P/P_<ref>大于0.1范围内的温度。荧光随温度升高而降低，可能是由于发光团基态的分子族减少所致。在实验条件不变的情况下，荧光的绝对强度随时间的推移而减小。24小时后，荧光强度约为ptep的80%，酞菁的约为60%。而P/P_<ref>与I/I_<ref>的关系不随时间变化而变化。

An optical pressure measurement system utilizing pressure sensitive paint which is based on the O_2 quenching of luminescence has been developed. The pressure sensitive paint is consist of Pt-Octaethelporphyrin or phthalocyanine as luminophore and O_2-permeable silicon polymer as matrix. Variation of strength of luminescence with change of partial pressure of oxigen is studied experimentally in the pressure range from 760 to 10^<-3> Torr and temperature range from 30 to 80 degree Celsius. A painted sample is radiated by UV light of wave length 390nm and fluorescence of wave length of 650nm from luminophore is detected by a CCD camera and the data are processed by a PC.Following results have been obtained :1.Ratio of fluorescence intensity I at pressure P to fluorescence intensity I_<ref> at a reference pressure P_<ref> satisfies the Stern-Volmer relation,<<numerical formula>>Taking into account the effect of the paint thickness, the above relation is modified, giving<<numerical formula>>However, the coefficient of square term is very small compared with the one of the linear term. The Stern-Volmer relatiion is not satisfied for P/P_<ref> less than 0.1. In this range dI/dP is large, showing the high sensitivity to the pressure.2.Absolute fluorescence intensity depends on the temperature. The relation betweem P/P_<ref> and P/P_<ref> does not depend on the temperature in the range P/P_<ref> larger than 0.1. Decrease of fluorescence with increase of temperature may be attributable to the decrease of morecular populatiion in the ground state of the luminophore.3.Absolute strength of fluorescence decreases with lapse of time, keeping the experimental condition unaltered. After 24 hours, the strength of fluorescece becomes about 80% PtOEP and about 60% for phtalocyanine. However, relation between P/P_<ref> and I/I_<ref> does not change in spite of laspe of time.