A CO2 gas laser in which the gas mixture that generates the laser beam is sandwiched between two water-cooled, electrode slabs. This space, which forms the resonator cavity, is only a few millimeters high. The beam exits the cavity through a small window and passes through a variety of optics before reaching the workpiece. Like the slow flow-axial laser, the hot gas molecules in the resonator cavity transfer their heat energy to the water-cooled electrodes by conduction. The small resonator cavity and water cooled electrodes effectively remove heat. Output power increases with the size of the electrodes, providing about 10kW per square meter. Diffusion cooled lasers generate a higher quality beam than all other CO2 lasers. Units with output powers from 1 to 8 kilowatts can be used to produce high-quality welds and cuts at relatively high speeds. Also known as a slab laser.