A processing apparatus may include: an extraction plate disposed along a side of a plasma chamber, the extraction plate having a first and second aperture, and middle portion between the first and second aperture, the first and second aperture being configured to define a first and second ion beam when the plasma is present in the plasma chamber and an extraction voltage is applied between the extraction plate and a substrate; a hidden deflection electrode disposed adjacent the middle portion outside of the plasma chamber, and electrically isolated from the extraction plate; and a hidden deflection electrode power supply to apply a bias voltage to the hidden deflection electrode, wherein the bias voltage is configured to modify a mean angle of incidence of ions and/or a range of angles of incidence centered around the mean angle of incidence in the first and second ion beam.