Due to their light mass, the electrons vibrate at a higher frequency than other plasma particles. As a result, they generate the effective frequency for shielding on the surface of a matter. To examine this frequency more precisely, a layer of thickness L from a homogeneous plasma is examined. Once this natural frequency is determined, a controller is designed to maintain the oscillation frequency constant also in the presence of disturbances which can occur. In this paper a Discrete Sliding Mode Control (DSMC) is proposed to maintain the natural frequency of the plasma constant. A proposition shows that a controller on just a grid point of the circular cell is enough to stabilize this frequency robustly even though in the presence of continuous disturbances and in the presence of unknown electrical initial fields. Simulation results validated the proposed control law.