Optical emission spectroscopy is an effective method for measuring key physical parameters in a vacuum arc. However

radiation absorption inside the arc plasma can significantly impact the spectral intensity and even distort the line shape. These effects hinder accurate spectral identification and consequently compromise parameter diagnostics based on optical emission spectroscopy. To address this issue

a collisional radiative model for vacuum arc was developed in this study. The model incorporated electron impact excitation/de-excitation

electron impact ionization/three-body recombination

spontaneous emission

and radiation absorption processes. The synthetic spectra were generated by coupling the model with the radiative transfer equation

and key plasma parameters were extracted by fitting the model to the experimental spectral data. The results indicate that

after taking into account the absorption effect

both spectral emission coefficient and spectral line broadening will increase

and the largest increment in the emission coefficient is found at 510.6 nm; furthermore

both electron temperature and electron density will increase

and the average increments in electron temperature and electron density are 0.05 eV and 7.06×1020 m−3

respectively; finally

the absorption effect can directly affect the particle density at the energy levels corresponding to the radiation by changing the net radiation rate

and can also indirectly change the population distribution of the arc by changing the energy distribution state.