Carbon and graphite materials have enjoyed consid­erable success as PFMs in current tokamaks because

of their low atomic number, high thermal shock resis­tance, and favorable properties. However, their use is not without significant issues, and their application in next-generation fusion energy devices is by no means certain. Significant among the issues related to carbon and graphite PFMs are neutron irradiation damage, which causes significant dimensional change and degrades the thermal conductivity resulting in increased PFC surface temperatures; physical sputtering, chemical erosion, and radiation enhanced sublimation, which cause surface material loss to the plasma and redeposition of carbon with tritium; and tritium inventory, which constitutes both a safety problem and an economic impediment to the use of graphite. Joining of CFC to heat sinks has witnessed significant development in the past few decades, which has resulted in good performing designs for near-term test machines such as ITER. The high heat loads and surface temperatures that result after plasma disruptions are also problematic for carbons. However, the same high temperatures make the use of Be, which has a significantly lower melting tem­perature, very unlikely.

Next-generation machines will impose increas­ingly greater thermal loads on their PFCs. High thermal conductivity CFC materials may offer a
solution for the high heat loads, but further research is needed to overcome the problems noted above and to secure the place of carbon materials in the future of fusion power reactors.