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

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, Si3, Si5, 01 and 03 where the numbers denote their coordination. The production of these defects increases with PKA energy except for the case Of Si5. A faster increase in the production rate with energy is observed for 0 1 and 03 types of defects with respect to Si3. Results are correlated to known experimentally observed defects. (c) 2007 Published by Elsevier B.V.