Abstract: A laser device has a bore formed by aligned apertured carbon discs with the ratio of the pitch distance between adjacent discs to the diameter of the apertures through the discs being between 1.8 and 3.0. An optimum value of this ratio is 2.2. The pitch distance is the distance from one surface of a carbon disc to the corresponding surface on an adjacent disc; this distance being measured parallel to the bore axis. This relationship of aperture diameter to pitch distance substantially eliminates sputtering of the carbon discs and gas clean-up during laser operation.