A system for coating a side surface of a moving substrate. The system includes an array of plasma sources, a first plurality of orifices located upstream of the array and a second plurality of orifices located downstream of the array. A coating reagent is injected from each orifice into a plasma jet issuing from plasma source associated with that orifice. A controller modulates the flow of coating reagent and the flow flush gas to the orifices according to the contours of the substrate and to the position of the substrate relative to the array. An additional plasma array and set of orifices may be employed to coat the opposite side surface of the substrate.