Dust grain in plasma is charged up by collecting electrons and ions from the
plasma, this charging process has been studied for laboratory dusty plasma. The
Orbital Motion Limited theory predicts the electron and ion currents toward the
grain, the discrete charging model uses these current values and converts it to
probabilities for collecting individual electrons and ions, this model assumed that
discrete charges will be collected at random intervals in a random sequence.
A program with FORTRAN programming language has been built to translate the
discrete model to simulate the charging process. Then, the value of the charge
number and their fluctuations as a function of time, charging time and mean
equilibrium charge number on the grain surface have been predicted. It has been
concluded that the grains were charged with negative and the charging process, in
general, was affected by grain size, electron temperature, and the background
plasma type.