Global model of cold atmospheric He + air plasmas: A comparison of Maxwellian and non-Maxwellian EEDFs

The electron energy distribution function (EEDF) of cold atmospheric plasmas (CAPs) is often assumed to be Maxwellian, but it is actually non-Maxwellian, as calculated from the Boltzmann equation. To determine the impact of the Maxwellian assumption, two global models with Maxwellian and non-Maxwellian EEDFs are developed for the He + air CAPs, and the resulting discharge characteristics and reactive species are compared. With the increasing air concentration from 100 to 50 000 ppm in He + air feeding gas, the simulation results of both global models display similar trends, and the orders of the densities of both global models are similar for the reactive species and each air concentration scenario. However, the Maxwellian assumption leads to lower electron temperature, weaker electronegativity, less power dissipation to Ion Joule heating, higher densities, and lagging peak points for most types of reactive species compared to using the non-Maxwellian EEDF. These findings indicate that the Maxwellian assumption is capable of capturing the main physicochemical features of He + air CAPs, but it can lead to large calculation errors at the quantitative level.