In situ luminescence qualification of radiation damage in aluminas: F-aggregation and Al colloids

• Correlation between IBIL and surface electrical degradation.
• Potential to remotely monitor degradation of insulating materials.
• Possibility for in situ recovery of the insulating properties by thermal annealing.

Recent work for in situ sequential measurement of ion beam induced luminescence and surface electrical conductivity has identified a correlation between surface electrical degradation and the luminescence for aluminas and sapphire during 45 keV He ion bombardment. Detailed measurements for the initial stages of degradation where rapid changes in the luminescence emission bands occur, have now identified processes related to oxygen vacancy (F centre) aggregation and aluminium colloid production as precursors to measurable surface electrical degradation in the irradiated region. This understanding enhances the possibility of using ion beam induced luminescence as a potential monitoring tool for material evolution and insulator surface degradation during irradiation, not only in ITER and future fusion devices, but also in present experimental reactor materials test programmes.