Identification and characterization of defects produced in irradiated fused silica through molecular dynamics

Abstract

We present molecular dynamics simulations of displacement cascades due to energetic recoils in amorphous silica, a candidate material for fusion applications. We have performed a statistical study of the different kinds of defects produced as a function of primary knock-on atom (PKA) energy. The range of energies studied is from 0.4 to 3.5 keV. We measure how the concentration of different kinds of defects vary with recoil energy and we catalogue these defect according to their potential energy, morphology and coordination. Our calculations show mainly four types of defects, Si 3, Si 5, O 1 and O 3 where the numbers denote their coordination. The production of these defects increases with PKA energy except for the case of Si 5. A faster increase in the production rate with energy is observed for O 1 and O 3 types of defects with respect to Si 3. Results are correlated to known experimentally observed defects.