Collision integrals for nitrogen and hydrogen ionized gas : the exact values and assessment of approximations

Collision integrals are calculated for the H–N++, N–H++, N2+2+–H, and N++–H++ interactions in the temperature range of 1000–60,000 K. The resulting collision integrals were fitted to simple functional forms. The applicability of commonly used approximations for calculation of the collision integrals is verified. Those approximations are simplification of exact potentials (especially the repulsive ones), use of polarizability potential for atom–ion interaction, and use of Coulomb screened potential for ion–ion interaction. The reported collision integrals are based on the ab initio calculated points of the potential energy curves, so that the error of fitting the points with analytical potential energy function is not present.