Arc Radiation Characteristics of CO2–O2 Mixtures at 0.1–0.8 MPa and 300–30,000 K

For high-voltage circuit breakers, it is necessary and urgent to explore SF6 alternative gases that are environmentally friendly. CO2 and its mixtures have been widely studied as eco-friendly insulation and arc-quenching media, but how to achieve large-capacity breaking to make it applicable to higher voltage levels is still a pressing issue. Radiation plays a crucial role in the energy dissipation process of the arc, especially under high-current conditions. Therefore, studying the radiation characteristics is beneficial for a better understanding of the breaking capacity of the arc-quenching medium. In this paper, the plasma composition of the CO2–O2 mixture at local thermodynamic equilibrium (LTE) is calculated using the minimization of Gibbs free energy. The radiation characteristics of the 70%CO2–30%O2 mixture over a pressure range of 0.1–0.8 MPa and a temperature range of 300–30,000 K are evaluated. It is found that increasing the pressure increases the number density of the gas, thus increasing the net emission coefficient. The radiation emitted by the 70%CO2–30%O2 mixture in the arc center is strongly absorbed within 1 mm, and the net emission coefficient of 70%CO2–30%O2 is higher than that of SF6 at the same pressure.