Surfaces in high-efficiency lasers and in electron, ion or plasma beam systems are exposed to very high heat flows and must withstand these for as long as possible and remove them without failure of the system. The heat is removed using helium gas as a coolant, which is supplied to the rear side of the surface by means of distributors. Individual cooling fingers are hereby arranged in rows directly on the distributors or collectors. The gas flow runs from a central bore in the cooling finger to the inner wall of a cap, which is artificially roughened by pins or recesses. This requires extensive manufacturing resources, but the cooling effect is low. The researchers at the Karlsruhe Institute of Technology (KIT) have succeeded in developing a new device for cooling a surface. This has a layer facing the heat flow which is made from a heat- resistant, low-wear-and-tear, low-erosion tungsten and is divided into individual segments. This device facilitates the formation of a modular array of cooling fingers which allows large cooling areas to be provided in parallel with high efficiency. The array of cooling finger modules for high-efficiency cooling guarantees optimum operation of high-efficiency lasers and particle flow systems.