Methods, systems, and apparatus for plating a metal onto a work piece are described. In one aspect, an apparatus includes a plating chamber, a substrate holder, an anode chamber housing an anode, an ionically resistive ionically permeable element positioned between a substrate and the anode chamber during electroplating, an auxiliary cathode located between the anode and the ionically resistive ionically permeable element, and an insulating shield with an opening in its central region. The insulating shield may be movable with respect to the ionically resistive ionically permeable element to vary a distance between the shield and the ionically resistive ionically permeable element during electroplating.