High Temperature in Absorption Measurements.
Abstract
The objective of this study was to measure the temperature dependence of the absorption coefficient of water vapor to determine the feasibility of using water vapor as a molecular seed to couple 10.6 micrometer CO2 laser radiation into a propellent for use in a high performance laser heated rocket thruster. A series of shock tube experiments were performed to determine the temperature dependence of the absorption coefficient of water vapor at high temperatures on the P(16), P(18) and P(20) 10.6 micrometer CO2 laser transitions. Measurements were made behind both incident and reflected shock waves encompassing a temperature range from 600 K to 3700 K at pressures from 1 to 40 atmospheres in 2, 5, and 10 mole percent water vapor in argon gas mixtures; a limited number of measurements were also made using 10 mole percent mixtures of water vapor in hydrogen or nitrogen. Conditions at several temperatures were sufficiently varied to investigate the effects of broadening on the absorption coefficient. Within the narrow spectral range from 944 to 948 cm covered in the measurements, no significant variation in the absorption coefficient was observed as a function of laser wavelength, water concentration, total pressure, or collision partner. These observations suggest that the water lines are sufficiently broadened to act as a continuum absorber under conditions to be found in a laser-heated rocket thruster. The measured laser high temperature absorption coefficients are 50% lower than the values obtained from the Ludwig empirical curve fit to low resolution data.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1981
- Accession Number
- ADA108601
Entities
People
- Evan R. Pugh
- Robert H. Krech
Organizations
- Physical Sciences (United States)