Embodiments of the present disclosure generally include an apparatus and methods for measuring and controlling in real-time a potential formed on a substrate in a plasma processing chamber during plasma processing. Embodiments of the disclosure include a plasma processing system that includes a substrate support disposed within a processing volume of the plasma processing system, the substrate support comprising a substrate supporting surface and a dielectric layer disposed between a first electrode and the substrate supporting surface. The plasma processing system further includes a first generator coupled to a second electrode of the plasma processing system, and a sensor disposed a first distance from the substrate supporting surface. The first generator is configured to generate a plasma within the processing volume. The first electrode is disposed a second distance from the substrate supporting surface, and the first distance is less than the second distance. The sensor is generally configured to detect an electric field strength and/or a voltage formed on the substrate during plasma processing.