Modelling of multi-electronic processes occurring during atomic collisions

In this thesis, we apply a non-perturbative semiclassical approach to describe the multi-electron processes occurring in non-relativistic ion-atom collisions. The treatment is semiclassical in the sense that the relative target-projectile motion is classically described by uniform rectilinear trajectories. In contrast, the electronic dynamics is treated in a quantum manner, by solving the time-dependent Schroedinger equation (TDSE) in a non-perturbative way. In our team, several codes have been developed to solve the TDSE. Their use has been strongly focused on taking into account a very large number of channels and all the couplings between them. These codes correspond to several thousand lines written in Fortran and can be applied to many collision systems. They are also the only ones that can handle collision systems with up to almost four active electrons. In the course of this work, we have studied several collision systems with respect to certain plasma diagnostic requirements (Li²⁺-H collision) and in relation to very recent experimental investigations (C⁴⁺, O⁶⁺, F⁷⁺-He heliumoid ion collisions and C³⁺-He collisions). In parallel, we have developed a code for constructing the electronic states to be included in the collision code, as this preliminary step is extremely important to describe the systems considered as well as to optimise the calculations, which are extremely CPU and memory intensive. (author)