Ion collision cross sections and transport coefficients extended to intermediate energies and reduced electric fields for He-2(+) ions colliding with He

Abstract

his work is devoted to the calculation of transport coefficients for He2+ ions in gaseous He at intermediate reduced electric fields. These swarm data are of great interest for a better understanding of the mechanisms of formation and propagation of the fast plasma bullets or ionization waves observed in dielectric barrier plasma jet devices. For transport data, the collision cross sections required are determined from several theoretical methods based on quantum, semiclassical, and hybrid approaches and a diatomics-in-molecules model for the potential energy surfaces of He3+. The corresponding collision cross sections are then used in an optimized Monte Carlo code to calculate the ion transport coefficients over a wide range of reduced electric fields extending over the experimental range. Calculated transport coefficients are compared with available experimental data at low electric fields. Moreover, an extrapolation method is used in order to determine the reduced mobility for stronger fields. A critical discussion has been performed on the pertinence and the reliability of these different methods of determination of collision cross sections needed for the calculation of ion transport data. Such ion data will be used in electrohydrodynamic and chemical kinetic models of the low-temperature plasma jet to quantify and to tune the active species production for a better use in biomedical applications.