Optical tomographic reconstruction of vacuum arcs considering effect of spectral broadening

Abstract The 3D evolution of key plasma parameters in a vacuum arc strongly affects the arc interrupting capacity of vacuum circuit breakers. However, traditional 3D diagnostics methods are typically based on the optically thin assumption, neglecting spectral broadening caused by the absorption effect. This limits accurate identification of internal radiation characteristics and spatial parameter distributions of the arc, thereby hindering the deeper understanding of arc evolution mechanisms. To address this issue, we proposed a 3D absorption correction algorithm considering spectral broadening. The algorithm first reconstructed the 3D emission coefficients of characteristic spectral lines at 510.6 nm and 515.3 nm using a tomography reconstruction method, and then calculated the upper-level atomic densities of characteristic spectral lines as well as the electron temperature. A modified collisional radiative model (CRM) was then employed to compute the electron density and population distribution, from which the line profiles and full width at half maximum (FWHM) were derived. Based on these parameters, the absorption coefficients and optical depth were obtained, and the Lambert–Beer law was applied to correct the radiation intensity. The results indicate that, after 3D absorption-corrected reconstruction with spectral broadening, the electron temperature, electron density, and atomic population in the axial magnetic field arc exhibit significant asymmetry. The peak electron temperature reaches 13 500 K, and the maximum electron density is 1.29 × 10 23 m −3 . Spectral broadening leads to a decrease in electron temperature, while its effect on electron density is minimal. In addition, the upper-level atomic densities are more sensitive to spectral broadening than those of the lower levels.