Carbon particles emission, brittle destruction and co-deposit formation: Experience from electron beam experiments and controlled fusion devices

Graphite erosion leading to the formation of carbon clusters and dust parti cles under high power deposition has been studied using an electron beam fa cility and in various types of controlled fusion devices with carbon walls. It is shown that brittle destruction of graphite takes place in both syste ms and it results in the production of debris of a sub-millimeter to millim eter size, in electron beam experiments fine grain graphites and carbon fib er composite have been subjected to intense transient heat loads with depos ited energy densities of up to several tens of MJ m(-2) in order to simulat e plasma disruptions (5 ms pulse duration) or vertical displacement events (100-1000 ms pulse duration). In a reversed field pinch the brittle destruc tion has been caused by a pronounced mode activity (and related power loads to the wall, over 1 GW m(-2)) at the very edge of the plasma during wall l ocking phase of discharges. Particles or dust generated during the thermal load tests and in fusion devices have been collected and analyzed using opt ical and various electron microscopy methods.