  The Numerical Advanced Model of Electron Cyclotron Resonance Ion Source
(NAM-ECRIS) is applied for studies of the physical processes in the source.
Solutions of separately operating electron and ion modules of NAM-ECRIS are
matched in iterative way such as to obtain the spatial distributions of the
plasma density and of the plasma potential. Results reveal the complicated
profiles with the maximized plasma density close to the ECR surface and on the
source axis. The ion-trapping potential dips are calculated to be on the level
of ~(0.01-0.05) V being located at the plasma density maxima. The highly
charged ions are also localized close to the ECR surface. The biased electrode
effect is due to an electron string along the source axis formed by reflection
of electrons from the biased electrode and the extraction aperture. The string
makes profiles of the highly charged ions more peaked on the source axis, thus
increasing the extracted ion currents.
