Surface electrical degradation for low mass ion implanted SiO2: Dependence on ion mass, energy and dose rate

KS-4V quartz glass (SiO2) is a candidate material to be used in ITER diagnostic systems where it will play an important role for optical components and possibly as electrical insulator. In addition to neutron and gamma radiation, the material will be subjected to bombardment by low energy ions and neutral particles. Previous work has shown severe electrical and optical degradation with a marked temperature dependence when the material is subjected to proton or alpha particle bombardment, due to loss of oxygen from the surface caused by preferential sputtering by energetic ions. In this work, a systematic study of ion bombardment induced surface degradation as a function of the ion mass, energy and dose rate has been carried out. A clear dependence on ion mass has been observed, with degradation occurring much more rapidly for heavier ions. Also the surface electrical degradation depends strongly on the implanted particle energy, degradation is higher for higher energy. No dependence on dose rate was observed.