Key factors governing net emission and reabsorption in C₄F₇N–CO₂–O₂ arcs

Arc radiative transfer is a key physical issue in the arc-extinction process of gas circuit breakers. Its behavior is jointly determined by net emission in the arc core and reabsorption in the edge region. To reveal the mechanisms governing net emission and reabsorption in the environmentally-friendly C₄F₇N–CO₂–O₂ arc, this study established a spectral-resolved radiative transfer model based on the line-by-line method and the discrete ordinates method under the assumption of local thermodynamic equilibrium, and systematically investigated the effects of mixing ratio, radial temperature distribution, pressure, and molecular spectra on radiative transfer. The results show that an increase in the temperature gradient accelerates radiative energy exchange within the arc column and increases the reabsorption fraction. Increasing pressure leads to a larger enhancement in the net emission region than in the reabsorption region, causing the boundary between the two regions to move outward, strengthening the escaping radiative power, and shifting its spectral composition toward intermediate-energy bands (visible light to mid-ultraviolet). Molecular spectra, especially molecular band spectra, have a significant influence on the reabsorption region. Neglecting molecular contributions will underestimate the reabsorption effect and overestimate radiative ablation of the nozzle wall. This study provides theoretical support for radiative modeling of environmentally friendly C₄F₇N-based circuit-breaker arcs and for evaluating nozzle ablation.