Distribution of the rotational temperature of $\rm C_2$ molecules in high-temperature regions in a supersonic airflow under injecting ethylene, propane, and oxygen in the discharge area

The distribution of the rotational temperature of $\rm C_2$ molecules in the anode–cathode gap of electric-discharge modules placed in a supersonic flow, observed in the discharge regions under injections of ethylene, propane, and oxygen, are studied with the use of emission spectroscopy. The rotational temperatures of the molecules are assumed to be close to gas-kinetic ones under experimental conditions. The analysis of the alternative way of comparing the gas-kinetic temperature with the rotational temperature of $\rm CN$ molecules shows the latter to be close to a higher vibrational temperature, apparently because $\rm CN$ molecules mainly originate in chemical reactions with the participation of strongly excited components arising under electron impacts. The correlation of the voltage across the discharge gap and the temperatures in the zones of energy release with the dynamic air pressure in the vicinity of the anode is derived.