A numerical investigation of damping of near-wall spanwise velocity fluctuations in a turbulent channel flow is carried out. Spanwise damping is realized with a body force which mimics the characteristic force distribution of plasma actuators. This force distribution is implemented in a direct numerical simulation. The body force is triggered by the signal of a sensor in upstream location. The control loop is applied with different actuator configurations, considering a spatially continuous and discontinuous body force distribution at the wall. The influence of distributed sensors and actuators of finite size on the control loop performance is investigated. The results show a reduction of the skin friction at the wall with maximum power saving rates up to 20%.