Excitation Temperature in High-Power Nitrogen Microwave-Induced Plasma at Atmospheric Pressure

Excitation temperature, rotational temperature, and electron density were obtained for a high-power (1-kW) microwave-induced nitrogen plasma (N 2 MIP) at atmospheric pressure generated by an Okamoto cavity. With 1 kW input microwave power, an excitation temperature of 5500 K, a rotational temperature of 5000 K, and an electron density in the 10 13 range were measured. Excitation and rotational temperatures were much closer than is the case with the commonly used argon inductively coupled plasma, suggesting that this N 2 MIP is closer to local thermodynamic equilibrium (thermal).