Infrared radiation measurements of a recombining CO2 plasma at atmospheric pressure

Overview & Synopsis

High resolution infrared emission measurements are performed on a high temperature CO2/Ar plasma. A 50 kW ICP torch was used to produce an atmospheric pressure CO2/Ar plasma jet close to Local Thermodynamic Equilibrium conditions at 6920 K. The emission measurements on this plasma jet were made between 0.9 and 5.6 μm. Our goal is to study the emission and verify that this emission is correctly modeled by the line-by-line radiation code SPECAIR. The measured spectra, calibrated in absolute intensity, are therefore compared with calculations done using SPECAIR. The absolute intensities of several atomic lines are used to measure the temperature of the plasma. This method gives the temperature quite accurately within the central hot portion of the plasma jet. We find that the molecular emission coming from this portion of the jet matches well the SPECAIR predictions. Large portions of the observed CO2 and CO molecular emission are emitted from the colder regions of the jet where the atomic lines are not sufficiently strong to provide a measure of temperature. In this paper, these colder portions of the molecular band emission are not compared with SPECAIR predictions.