Chemical erosion of doped graphites for fusion devices

Doping of carbon generally results in a reduction of its chemical reactivity during hydrogen ion bombardment. Due to preferential sputtering of carbon, the dopants may be enriched at the surface, resulting in an additional reduction of the erosion yield. Dopants in the form of sub-μm precipitates with a very homogeneous distribution lead to in a more effective reduction of both chemical erosion processes, Ytherm and Ysurf. However, dopants may degrade the thermal conductivity of graphite, which has to be avoided. First results on the development of carbon materials doped with different carbides and with optimized microstructure and thermomechanical properties show that VC acts as an effective catalyst for graphitization causing an improvement of the thermal conductivity. It leads further to a reduction of both, the Ytherm and the Ysurf chemical erosion processes, which is partly attributed to surface enrichment but is also the result of a chemical influence.