A method of improving the performance of a charged beam apparatus. The method including: providing a chamber having an interior surface; providing a pump port for evacuating the chamber; providing a substrate holder within the chamber; forming a charged particle beam within the chamber, the charged beam generated by a source and the charged particle beam striking the substrate; and placing one or more liners in contact with one or more different regions of the interior surface of the chamber, the liners preventing material generated by interaction of the charged beam and the substrate from coating the one or more different regions of the interior surface of the chamber.