Rodoljub Simovic

The albedo problem of low-energy light ions treated analytically in the DP0 flux approximation

The energy dependent albedo problem of low-energy light ions from heavy targets is considered in a multiple-collision model. The ion transport equation is treated with the assumptions that (i) the distribution function is almost isotropic and (ii) the transport cross section depends only on initial ion energy. The transport equation is Laplace transformed in relative path length and solved by applying the DP0 flux approximation in angle. Reflected energy spectra, particle and energy reflection coefficients are analytically derived. A comparison of DP0 results with age theory, computer simulation data and experimental results is made.

ANALYTIC APPROXIMATIONS OF THE H-FUNCTION BASED ON DIFFERENT DPN PROCEDURES

Abstract Three approximate analytic expressions for the H-function are derived by using ordinary and flux decomposition DPN method. The accuracy of approximations is examined and comparison with similar formulas of the other authors is performed. As an application of the approximate H-functions the energy-dependent particle albedo problem is treated analytically.

Analytical solutions of the Boltzmann transport equation for light ion reflection

Reflection of light ions from solids have been calculated in the low-energy region where large-angle multiple collisions dominate. Backscattering parameters are obtained as a solution of the Boltzmann equation in the transport approximation. The Laplace transformed equation, which has the form of a one-group transport equation for isotropic scattering, has been solved by using an accurate analytical approximation of Chandrasekhar`s H-function. Universal curves as well as analytical results are presented for reflected energy spectra integrated over all ejection angles, particle and energy reflection coefficients, and total angular distribution of backscattered ions. Calculations have been done for different angles of incidence. For normal ion incidence and primary energies higher than 100 eV, the agreement between analytical theory and computer simulation data is satisfactory. 34 refs., 11 figs.