Interaction of a tin-based capillary porous structure with ITER/DEMO relevant plasma conditions

Sn filled capillary porous structures were exposed to high flux low temperature plasma conditions at the Pilot-PSI linear device. Enhanced erosion above that expected classically was investigated via spectroscopic observation of Sn0 emission from the plasma in front of the target surface while the surface temperature was monitored by both thermography and pyrometry. An anomalous erosion flux was observed as temperature increases, with onset for this occurrence varying strongly between different ion species. The results appear incompatible with existing ‘adatom’ models for the anomalous erosion flux. Further targets were exposed in turn to increasing heat fluxes and the heat removed determined from cooling water calorimetry, which was then compared to a solid Mo reference target. At high powers the total energy of the cooling water is reduced, indicating a shielding of the surface from the plasma heat flux by the vapour cloud in front.

PSI

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