a plasma system for processing large area substrates . in one embodiment the system includes a plurality of radiofrequency plasma sources removably attached to the rf transparent windows of a processing chamber . the number and distribution of sources is varied to provide the size and uniformity of the plasma field required to treat the substrate . a plurality of plasma probes , such as langmuir probes , faraday cups and optical sensor are positioned within the chamber and in electrical communication with the plasma sources adjust the rf field produced by the individual sources to maintain the desired degree of field uniformity .