Role of ion beam heating in blistering behaviour of solids

Abstract

Abstract Evolution of subsurface damage microstructures such as bubbles, dislocations and microcracks during gaseous ion implantation decreases the thermal conductivity of the implant/damage region by decreasing the mean free path of the heat carriers, electrons and phonons, due to enhanced scattering. Consequently the dissipation of the beam power dumped into the implanted surface layer is interrupted, which results in the increased effective implantation temperature. The solution of steady-state heat conduction equations corresponding to ion implantation experiments is presented to give the beam spot temperature. A comparison with experimental observations like the sudden rise of temperature at the moment of blistering, red glow of blister covers and sponge-like blister skins provides an estimation of the thermal conductivity near the critical dose for blistering. It was found that the conductivity decreases by 4 to 6 orders of magnitude from its bulk value. The role of such ion-induced temperature rise in relevance to damage microstructure and surface blistering is discussed. Furthermore, the implications for wall erosion and heat transfer in fusion reactors are outlined.