Abstract: An apparatus, system and method for controlling parameters attending the emission of a vaporized material from a source in a HV environment utilizes at least one shutter which is rotatably mounted over an exit opening through which vaporized material must exit the source. The shutter has a closure portion and is mounted adjacent the exit opening associated with the source for rotation about an axis so that by rotating the shutter about the rotation axis, the closure portion repeatedly covers and uncovers the exit opening in an intermittent fashion to prevent the emission of a vaporized material from the source during the periods of shutter rotation during which the exit opening is covered by the closure portion and to permit the emission of a vaporized material from the source during the periods of shutter rotation during which the exit opening is uncovered by the closure portion.