Prediction of total emissivity of nitrogen- broadened and self-broadened hot water vapor

Total emissivity predicted for nitrogen-broadened and self-broadened hot water vapo

INFRARED INTEGRATED BAND INTENSITY MEASUREMENTS BEHIND REFLECTED SHOCK WAVES

Author Institution: General Dyamics/Astronautics, Space Science Laboratory“A shock wave technique is described which provides a means of measuring the infrared integrated intensity of molecular bands at elevated temperatures. The total bund emission from the high temperature gas region existing between the end plate of a shock tube and the reflected shock wave was measured using a rapid response infrared detector. The emission is obtained as a function of path length as the reflected shook wave recedes from the end plate. The initial concentration, shock velocity and reflected shuck pressure were measured and the final conditions of the test gas were calculated from the normal shock relations. An absolute intensity calibration of the detector and monochromator system was obtained using a standard blackbody source. The absolute band intensity is obtained from the slope of a plot of total emissivity versus optical path length. The method has been used to measure the absolute intensity of the 2.7 micron combination band of $CO_{2}$ in the temperature region $1000^{\circ} K$ to $3000^{\circ} K$. To insure adequate pressure broadening for this weak band and yet to remain within the optically thin linear region, the measurements were made at 2.5 atms total pressure and 0.1 atm $CO_{2}$ partial pressure.

INTEGRATED INTENSITY MEASUREMENTS ON THE FUNDAMENTAL AND FIRST OVERTONE BAND SYSTEMS OF CO BETWEEN 2000∘2000^{\circ} AND 5000∘K5000^{\circ}K.

This work was supported by Project DEFENDER, Advanced Research Project Agency, AO363, through the Air Force Cambridge Research Laboratories, AF19(628)-4360.Author Institution: Space Science Laboratory, Mail Zone 596-00, General Dynamics/ConvairMeasurements have been made of the total absolute integrated intensities of the fundamental and first overtone band systems of CO at various temperatures within the range $2000^{\circ}$ to $5000^{\circ}K$. The CO gas sample was studied in emission using a reflected shock wave technique to raise the sample to the high temperatures. The experiment determines the total integrated band emission as a function of optical pathlength. For optically thin gases, the integrated emission is related to the integrated intensity in a simple fashion. Within the temperature range used in the present experiment, the integrated intensity of the CO fundamental band system remains constant. However, the integrated intensity of the CO first overtone band system shows a very small increase with increasing temperature. The temperature dependencies of the two band systems are in agreement with the theoretical temperature dependencies determined assuming a harmonic oscillator approximation to the CO molecule