Calculated plasma parameters and excitation spectra of high-pressure helium discharges

A collisional-radiative model was used to study the kinetics of an atmosphe ric pressure helium discharge. The electron kinetics was obtained from a tw o-term solution of the Boltzmann equation with electron-electron collisions included. The distribution of the helium electronic excited states was com pared to measured values and used to calculate excitation temperatures. The results show that a unique value of the excitation temperature cannot be u sed to characterize the whole electronic states distribution, because the p lasma is not in local thermodynamical equilibrium under the conditions cons idered. Other calculated discharge parameters, such as the electron tempera ture, the maintenance electric field, the density of metastable atoms in th e 2(3)S state, and the ion densities are presented and compared to experime ntal data when available.