between the plasma and the workpiece with the aperture being positioned such that the impinging plasma has the appropriate footprint 908 the footprint can be determined for example at the point along the primary axis of the plasma vertical in fig1 at which the proper amount of heat will be applied to the workpiece such that the torch can be moved an appropriate distance from the workpiece once the aperture and torch are in position relative to the workpiece reactive atom plasma processing can be used to modify the surface of the workpiece 910 such as to etch smooth polish clean and or deposit material onto the workpiece the torch and or workpiece can be moved relative to each other in order to process the necessary portion s of the workpiece the movement can be any appropriate movement such as along a predetermined path along a raster or u201c fixed u201d pattern or can be determined dynamically be measuring the surface to be modified the use of an aperture can help to circumvent inconveniences associated with replacing the torch while enabling smaller tool footprints than previously obtainable in order to prevent arcing to ground an aperture device can be electrically isolated the electric isolation can occur in one embodiment by suspending the aperture device from an insulating rod such as a ceramic rod having a high melting point in order to withstand thermal shock as well as the high temperatures of the plasma an aperture device can be constructed of an appropriate.