Abstract: A corona discharge device having a roll electrode and a segmented corona discharge electrode assembly mounted in a spaced relation to the roll electrode, the electrode assembly including a number of electrode segments mounted in a staggered relation with respect to said roll electrode, each segment including a hollow tubular electrically conductive electrode and a cup-shaped insulator mounted on the end of the electrode, the insulator including a base having an opening in the center, a tubular wall section surrounding the outside of the electrode and a vent tube aligned with the opening in the base and extending into the electrode to provide a vent passage for drawing air or blowing air across the face of the surface of the base of the insulator, and an electricity conductive adhesive for securing the insulator to the electrode and providing an even electrical field between the base and the surface of the base race electrode.