A process and apparatus for deposition of a carbon-rich coating onto a moving substrate is provided. The process and apparatus involve the creation of an electric field surrounding a rotatable electrode in a carbon-containing gaseous environment. This results in carbon-rich plasma formation, wherein the electrode is negatively biased with respect to the electrode which results in ion acceleration from the plasma toward the electrode. Ion bombardment continuously occurs on a substrate in contact with the electrode producing a continuous carbon-rich coating over the length of the substrate.