In order to measure erosion/redeposition in fusion devices, a new diagnostic based on speckle interferometry is investigated. First experiments performed on carbon fiber composite (CFC) materials have shown that this technique is able to measure a modification of the surface in the range of 1 μm. Further experiments have been performed on different materials using a second wavelength in order to carry out 3D measurements of the surface and to increase the dynamic range of the depth measurement. A diagnostic, based on two-wavelength TV-holography to measure in situ erosion/redeposition during long duration discharges on the CIEL limiter in Tore Supra, is under development at CEA Cadarache.
"Speckle interferometry application for erosion measurements in fusion devices", Proc. SPIE 4933, Speckle Metrology 2003, (27 May 2003); doi: 10.1117/12.516650; https://doi.org/10.1117/12.516650