Plasma-induced changes of a metallic divertor neutralizer plate analysed by photoacoustics

A metallic divertor neutralizer plate of the ASDEX tokamak has been analysed by photoacoustics, a thermal wave method with acoustic detection, to obtain space resolved thermal depth profiles and to characterize the plasma-induced changes of the plate material. In the intersection region between plasma separatrix and neutralizer plate where the maximum power deposition occurred during incorporation in ASDEX, the effusivity √kρc, the thermophysical parameter relevant for time dependent surface heating processes, increased about 18% in comparison to its original value. (orig.)