A model for arc plasma's optical diagnosis by the measurement of the refractive index

► A model, which introduces the ionization degree of plasma, is deduced to reconstruct temperature distribution of arc plasma. ► The distribution and imprecision of the reconstructed temperature indicate that the new model is reasonable and effective. ► This study will provide some reference on plasma's temperature and electron number density diagnosis by the optical methods which are based on the measurement of the refractive index, as well as be benefit to expand the applicable range of OCT in plasma's diagnosis.