A beamline ion implanter and a method of operating a beamline ion implanter. A method may include performing an ion implantation procedure during a first time period on a first set of substrates, in a process chamber of the ion implanter, and performing a first pressure-control routine during a second time period by: introducing a predetermined gas to reach a predetermined pressure into at least a downstream portion of the beam-line for a second time period. The method may include, after completion of the first pressure-control routine, performing the ion implantation procedure on a second set of substrates during a third time period.