Elastic He+ on He collision cross-sections and Monte Carlo calculation of the transport coefficients of He+ ions in gaseous helium

Integral and differential cross-sections for elastic collisions of He+ ions in the ground state (2S) with neutral He atoms are calculated, for centre-of-mass energies between 0.001 and 10 eV, using the partial waves method. The scattering phase shifts are calculated using the JWKB semi-classical approximation, with modified Tang–Toennies ion–atom (TTIA) potential energy curves, that describe spectroscopic data, dissociation energies and equilibrium internuclear distances, and the long-range interaction potentials. These cross-sections are used in a detailed three-dimensional Monte Carlo simulation model to calculate the main transport coefficients describing the ion drift through the neutral gas, as a function of the gas temperature and the reduced uniform electric field. Calculated drift velocities, ion mobilities, as well as longitudinal and transverse diffusion coefficients for He+ atomic ions in gaseous He, at temperature T=293 K and reduced electric fields, E/N, in the 1 to 300 Td (1 Td=10−17 V cm2) range, are reported and compared with the limited experimental data available in the scientific literature. The calculated drift velocities range from 28.31 m s−1 at 1 Td to 3685.0 m s−1 at 300 Td.