Radiation damage and xenon release in quartz and fused silica following ion bombardment

Abstract

AbstractSingle‐crystalline quartz and fused silica were bombarded with 40 keV xenon ions to give integrated ion doses of up to 2 × 1016 ions/cm2. At low dose (8 × 1010 ions/cm2) diffusional release processes dominated with activation enthalpies of 58 and 61 kcal/mol for quartz (diffusion along and perpendicular to the c‐axis respectively) and 72 kcal/mol for fused silica. Diffusion in the amorphous phase was markedly slower than diffusion in the crystalline phase. At doses ≧ 4 × 1013 ions/cm2 radiation damage in the form of a phase change to a quasi‐amorphous state occurred in quartz, as revealed by reflection electron diffraction. The annealing of this structural damage coincided with enhanced thermally activated gas release at temperatures below those of volume diffusion. Fused silica showed a similar enhanced release at high bombardment dose. Thus, the quasi‐amorphous phase produced by ion bombardment is different from that of fused silica. The present results indicate further, in agreement with the literature on neutron irradiated quartz and fused silica, that both materials approach a common state at a high level of radiation damage.