The use of carbon fibre composites in divertor target plate tiles and structures

Carbon-carbon fibre composite (CFC), in the form of target plate tiles, is a standard material for intercepting conducted power in divertors. Its good thermal conductivity and ability to withstand high temperatures without melting give it an advantage over other materials for plasma facing components. Supporting structures are generally made from stainless steels or Inconels. In a radiating divertor, designed to operate with detached plasmas, heat is deposited by radiation on to both plasma facing components and supporting structures. Consequently CFC has been chosen as a structural material to overcome the limitations of metal structures. The various material properties such as thermal conductivity, strength, rigidity and anisotropic behaviour need to be taken into account for the design. Tests have been carried out on a range of CFC materials from different manufacturers to determine these properties. Thermal behaviour has been studied through power load tests in the JET Neutral Beam Test Bed. Structural properties have been measured through mechanical tests on prototype assemblies. Clamping and joining methods have been developed for the assembly of CFC plates to form structurally and thermally robust tile carriers for a radiating divertor.