A terminal system for an ion implantation system has an ion source with a housing and extraction electrode assembly having one or more aperture plates. A gas box is electrically coupled to the ion source. A gas source is within the gas box to provide a gas at substantially the same electrical potential as the ion source assembly. A bleed gas conduit introduces the gas to a region internal to the housing of the ion source and upstream of at least one of the aperture plates. The bleed gas conduit has one or more feed-throughs extending through a body of the ion source assembly, such as a hole in a mounting flange of the ion source. The mounting flange may be a tubular portion having a channel. The bleed gas conduit can further have a gas distribution apparatus defined as a gas distribution ring. The gas distribution ring can generally encircle the tubular portion of the mounting flange.