  In the heliosphere, especially in the inner heliosheath, mass-, momentum-,
and energy loading induced by the ionization of neutral interstellar species
plays an important, but for some species, especially Helium, an underestimated
role. We discuss the implementation of charge exchange and electron impact
processes for interstellar neutral Hydrogen and Helium and their implications
for further modeling. Especially, we emphasize the importance of electron
impact and a more sophisticated numerical treatment of the charge exchange
reactions. Moreover, we discuss the non-resonant charge exchange effects. The
rate coefficients are discussed and the influence of the cross-sections in the
(M)HD equations for different reactions are revised as well as their
representation in the collision integrals. Electron impact is in some regions
of the heliosphere, particularly in the heliotail, more effective than charge
exchange, and the ionization of neutral interstellar Helium contributes about
40% to the mass- and momentum loading in the inner heliosheath. The charge
exchange cross-sections need to be modeled with higher accuracy, especially in
view of the latest developments in their description. The ionization of Helium
and electron impact ionization of Hydrogen needs to be taken into account for
the modeling of the heliosheath and, in general, astrosheaths. Moreover, the
charge exchange cross-sections need to be handled in a more sophisticated way,
either by developing better analytic approximations or by solving the collision
integrals numerically.

Solar and Stellar Astrophysics