Measurement and Modeling of OH, NO, and CO Infrared Radiation at 3400 K

The infrared emission spectrum of an air plasma containing small quantities of CO 2 and H 2 O was measured and modeled in absolute intensity in the spectral range 2.4-5.6 μm. A 50-kW radio-frequency inductively coupled plasma torch was used to produce the air plasma in local thermodynamic equilibrium. The temperature profile measured by emission spectroscopy peaks at 3400 K. The absolute intensity emission spectrum was measured and compared with numerical simulations obtained with the line-by-line radiation code SPECAIR. Spectroscopic models incorporated into the SPECAIR code include the infrared rovibrational bands of OH, NO, and CO. Absorption of the plasma emission by room-air CO 2 and H 2 O in the optical path between the plasma and the detector is taken into account. Plasma emission from CO 2 (v 1 + v 3 ) and (v 3 ) bands is also modeled, using a correlated-k model