INNOVATIVE DESIGN AND MATERIAL SOLUTIONS OF THERMAL CONTACT LAYERS FOR HIGH HEAT-FLUX APPLICATIONS IN FUSION DEVICES

One difficulty associated with the design and development of sacrifici al plasma facing components that have to handle the high heat and part icle fluxes in ITER is achieving the necessary contact conductance bet ween the plasma protection material and the high-conductivity substrat e in contact with the coolant. This paper presents a novel bond idea w hich is proposed as one of the options for the sacrificial energy dump targets located at the bottom of the divertor legs. The bonded joint in this design concept provides thermal and electrical contact between the armour and the cooled sub-structure while promoting remote, in-si tu maintenance repair and an easy replaceability of the armour part wi thout disturbing the cooling pipes or rewelding neutron irradiated mat erials. To provide reliable and demountable adhesion, the bond consist s of a metal ahoy, treated in the semi-solid phase so that it leads to a fine dispersion of a globular solid phase into a liquid matrix (rhe ocast process)(1). This thermal bond layer would normally operate in t he solid state but could be brought reversibly to the semi-solid state during the armour replacement simply by heating it slightly above its solidus temperature. Material and design options are discussed in thi s paper. Possible methods of installation and removal are described, a nd lifetime considerations are addressed. In order to validate this co ncept within the ITER time-frame, a R&D programme must be rapidly impl emented.