Interactions of charge exchange and ionization of fast, low-charged heavy ions are very important in heavy ion beam inertial confinement fusion. These effects are crucial indetermination of the final focusing in the chamber. However, corresponding cross section data is very limited and/or not accurate over the entire range of energies and ions of interest. This paper reports on our recent studies of cross sections for interactions of heavy ions with noble gases. Since a quantum mechanical treatment encounters a complex many-body problem, a classical trajectory Monte Carlo method is employed. The distribution of inner electrons is estimated by a modified Hartree-Fock model for the purpose of decreasing the number of electron orbits calculated, a micro-canonical ensemble for the initial electron probability distribution is introduced to describe quantum mechanical uncertainty. Cross sections are evaluated over a limited energy range; then scaling laws are developed to reflect the change probability for the beam charge state over a larger energy range.