Progress in the design of mechanically attached, conductively cooled low-Z armour tiles for the NET integrated first wall

For the NET device complete or extensive coverage of the first wall with a low-Z armour is envisaged. This armour may comprise a general protection, ∝90% total first-wall surface, of low-temperature conductively cooled tiles, complemented by a local protection of radiatively cooled tiles in regions where near peak fluxes are incident. A low-temperature (∝1000deg C) carbon-based armour, cooled via conduction to the reference NET integrated first wall, has been developed using currently available materials. The armour comprises a small square tile fabricated in high-conductivity 3-D or random-fibre carbon fibre reinforced carbon composite attached to the steel first wall via a stainless-steel/refractory metal stud assembly. Attachment forces are maintained within acceptable limits, particularly during baking, through material selection and component geometry. To ensure effective heat transfer throughout the duty cycle an intermediate conductive layer of a highly compliant material is foreseen. The scope of the paper covers the design of the armour assembly for proof of principle testing with the NET first-wall test section, TS1, and reports the results of supporting thermomechanical analyses. (orig.)