Collisional-radiative calculation of the He I line emission spectrum taking into account the radiation trapping effect

We performed collisional-radiative calculations to determine the line intensity ratios of the He I transition emission spectrum as a function of the electron density by using the collisional-radiative model taking into account the radiation trapping effect. The radiation trapping effect was estimated by using the optical escape factor on the assumption that the spatial distribution of groundstate atoms was given by a Gaussian function. Three line intensity ratios of 504.8 nm/471.3 nm, 492.2 nm/471.3 nm, and 492.2 nm /504.8 nm were calculated and compared with the results calculated using the Ballance model in which the radiation trapping effect is not included.