Helium Jet-Cooled Tungsten Divertor Concept

Helium cooled refractory metal heat sinks are being considered for the divertor sections for several fusion energy reactor concepts. Recent EU results have shown considerable promise for jet impingement type helium cooling techniques for high heat flux (HHF) applications. However, because of the small size of the "pin-like" units (1.5-2 cm diameter), a large number of these heat sinks would be needed for the divertor section of a reactor. Recently, a mid-size helium jet-cooled configuration with good heat flux accommodation potential has been proposed by the ARIES Team. This design is comprised of concentric tubes with a slot in the internal tube for helium impingement cooling of the external tube. As a result, the concentric tube design has an increased coverage area of approximately 5 times the "pin-like" units. To demonstrate the feasibility of this improved helium cooled tungsten divertor concept, advanced net shape refractory metal forming techniques are being developed. Electrochemical forming techniques have been used to produce tungsten heat sinks that are 99% of the theoretical density of tungsten. Preliminary thermal response tests have demonstrated the ability of a tungsten heat sink with helium impingement cooling to reduce its average surface temperature by -20% as compared to the average surface temperature for a straight bore tungsten heat sink under the same heat flux.