Behaviour of carbon and boron-carbon materials at high temperatures in TEXTOR

Test limiters made from graphite and boron-doped graphite have been exposed in TEXTOR to high heat loads up to about 30 MW/m2. Maximum surface temperatures up to 3000deg C have been reached. Boron sublimes thermally from the boron-doped graphite exceeding the boron sputter-fluxes at about 2000deg C. At the same temperature the carbon release increases sharply. The carbon release from the pure graphite shows no measurable increase up to surface temperatures of about 2200deg C and increases then steeply. The results are compared with the expected carbon and boron release by physical sputtering, radiation enhanced sublimation and normal thermal sublimation. (orig.)