  The ion production in an ECRIS is modelled using a particle-in-cell
Monte-Carlo collision code in a three-dimensional geometry. Only the heavy
particles (ions and atoms) are tracked, with the electron density determined
from the requirement of quasi-neutrality, and the electron temperature is a
free parameter. The electric fields in the plasma are assumed to be negligibly
small, and the ion confinement due to a "potential dip" is neglected. It is
found that experimentally observed features of ECRIS plasma are closely
reproduced by the code, including the charge-state-distributions of extracted
ion beams and sputtering patterns inside the source. The isotope anomaly is
observed for the mixture of 20Ne + 22Ne isotopes, and some explanation for the
effect is given. Possible connection between the wall-coating effect and
parameters of the fast atoms created in collisions of the ions with the walls
is discussed.
