Design of a real-time control scheme to provide an optimal etch rate and uniformity in reactive plasmas is not easy because of the complexity of the plasma and surface chemistries, and because it is difficult to choose a measurable and controllable variable that directly represents etch rate and uniformity. In this article, a feedback control system is proposed in which two independently powered and controlled coils are used to control a density measurement based uniformity in an inductively coupled plasma reactor. Stability limits and the utility of this control system are investigated using a simplified two-dimensional hybrid model.