Nanocrystalline diamond coating of fusion plasma facing components

Nanocrystalline diamond layers were deposited by hot-filament CVD on several substrates including molybdenum tiles and foils, graphite blocks and silicon wafers. The structural characterisation of the deposited layers, achieved by SEM, AFM, Raman and X-ray photoelectron spectroscopies, showed the typical features of nanocrystalline diamond.A nanocrystalline diamond coated molybdenum tile was exposed to a fusion grade deuterium plasma in the MAST tokamak, with a plasma current of 700 kA, core electron temperature of about 0.6 keV, and total exposure time of about 1 s. The diamond coating showed good resistance to the extremely harsh conditions of the fusion plasma edge.