Collisional radiative model for neon plasma with relativistic electron impact fine-structure excitation cross sections

Most of the earlier plasma diagnostic studies have focused on Ar, Kr and Xe but not much attention has been paid to study Ne plasma which is equally important. In the present work, we take up the diagnostics of low temperature Ne plasma through optical emission spectroscopy (OES) technique. In this method, the emission measurements are combined with suitable collisional radiative (CR) model to extract electron temperature, electron density and population of species. A large amount of reliable electron impact excitation (EIE) cross sections data are required for optical-based plasma diagnostic techniques and at present these are not available in accurate and adequate manner for Ne. Therefore, there is need to produce these data first and then resort to a reliable plasma modeling. We calculate the required fine-structure EIE cross sections of Ne using fully relativistic distorted wave (RDW) theory and then incorporate into the CR model for the neon plasma modeling. For the diagnostics our CR model is coupled with the Optical emission spectroscopy (OES) measurements of Navratil et al. In our CR model we take into account 40 fine structure states of Ne corresponding to 2p⁵3s, 2p⁵3p, 2p⁵4s, 2p⁵4p and 2p⁵3d configurations along with its ground and ionic state. We calculate the required electron impact excitation cross- sections from the ground and excited states to upper states using fully Relativistic Distorted Wave (RDW) theory. In the calculation, the ground and excited states of the neon are represented through relativistic multi-configuration Dirac-Fock (MCDF) wave functions which are obtained from GRASP2K code. The projectile electron wave functions are obtained by solving The Dirac equations in the field of spherically averaged static potential of the Ne atom. The electron excitation T matrices are calculated and the cross sections for the possible different fine structure transitions are obtained in the electron impact energy range up to 500 eV. Thereafter, these cross sections are incorporated in the CR model of Ne plasma following our earlier work on Kr and coupling our model with OES measurements of Navratil et al. where they obtained the intensities of the lines from 2p⁵3p → 2p⁵3s transitions. In the conference we will present the details of RDW method and the calculated different cross sections as well as CR model of the Ne plasma along with the obtained parameters. (author)