High heat flux simulation experiments with improved electron beam diagnostics

Plasma facing materials such as beryllium, carbon or tungsten are subjected to intense heat loads during off-normal plasma operation. To simulate these events, electron beam experiments are performed routinely to investigate the thermomechanical performance of the materials. In these tests, main emphasis has been laid on the material damage such as melting, cracking, and degradation of the materialsʹ properties. On the other hand, severe thermal loads are also associated with the release of particles from the loaded surface (metallic droplets or carbon dust) which might contaminate the plasma in future fusion devices. To investigate these phenomena in high heat flux simulation tests, extensive diagnostics are required to evaluate the actual material loading and to characterize the resulting material damage. Among these are measurements of the electrical current through the test coupons and high-speed IR pyrometry.