Application of tungsten–copper composite heat sink materials to plasma-facing component mock-ups

Abstract

The exhaust of power and particles is currently considered as one of the ultimate challenges in view of the design of a power producing magnetic confinement thermonuclear fusion device, like DEMO. One predominantly challenging aspect in this regard is the design and manufacture of divertor target plasma-facing components (PFCs) that have to sustain substantial particle, heat and neutron fluxes during fusion operation. With respect to the design of highly loaded actively cooled PFCs, copper (Cu) alloys are currently regarded as state-of-the-art structural heat sink materials. However, it has been underlined that the use of Cu alloys in PFCs implies issues mainly due to the behaviour of these materials under neutron irradiation characterised by a pronounced loss of ductility at lower and a loss of strength at elevated temperatures. These operating temperature limitations impose a strong constraint on the design of divertor PFCs and have regarding DEMO in the literature been termed a high impact design engineering risk. Against this background, the development of tungsten-copper (W-Cu) composites as potentially advanced heat sink materials for highly loaded PFCs was pursued by the authors during recent years. The progress of these developments is discussed in the present paper in terms of results of high-heat-flux tests conducted on PFC mock-ups that comprised W-Cu composite material heat sinks. Overall, the results of these tests indicate that W-Cu composites can indeed be regarded a viable class of advanced materials for the heat sink of highly loaded PFCs.

Preparation of W-Cu composites by infiltration of W skeletons – review

“…In the more advanced configurations, such as combustion heating + centrifugal infiltration, the tungsten preform is placed at the extremity, in the direction of the centrifugal force, this is followed by the copper and termite (or their mixture) towards the center [29][30][31]. In [3,33] the centrifugal infiltration concept was used in a cylindrical geometry, when a tungsten preform consisting of braided fibers was placed in a rotating tube, with the copper infiltrating it from the center. This way, composites of tubular shapewere produced.…”

Heat exhaust in fusion reactors and its impact on the sustainability of fusion electricity

“…The engineering challenge consists in managing the increased thermal stresses that arise from the low thermal conductivity of RAFM steels, which is 10-15 times lower than that of Cu. W-based composite materials are also actively investigated, such as W/Cu composite materials for the divertor [11], whose high heat fluxes exclude the possibility of using an insulating material such as steel, and W/Fe composites. Indeed, W provides a good resistance to neutron embrittlement, due to the high number of protons in the nucleus.…”

Effects of Bonding Treatment and Ball Milling on W-20 wt.% Cu Composite Powder for Injection Molding

“…Tungsten–copper (W-Cu) pseudo-alloys are widely used in the manufacturing of electrical contact materials, electrodes, thermal management devices, and conductive inks for ceramic metallization due to their high electrical conductivity, high thermal conductivity, low coefficient of thermal expansion (CTE), and many other excellent properties [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. With the rapid development of microelectronics and packaging technology, W-Cu heat sink components become smaller, and their shapes become more complex.…”