Surface erosion and modification by energetic ions

Surface erosion and modification by energetic highly charged and cluster ions are important in the development of semiconductor devices, TeV accelerators, fission and fusion reactors, and in the development of extreme ultra-violet lithography devices. Gas cluster ion beam (GCIB) surface treatment can significantly mitigate the high-gradient electric vacuum breakdown of rf-cavities. GCIB can also mitigate Q-slope drop in superconducting Nb-cavities. Various mechanisms of the highly charged ion (HCI) energy transfer into the solid target, such as hollow atom formation, charge screening and neutralization, shock wave generation, and sputtering were analyzed. Surface erosions caused by GCIB, HCI bombardments, and by low energy He+ and H+ ions typical for fission and fusion devices were studied by using molecular dynamics simulation. A He bubble splashing mechanism of liquid Li containing was developed, and surface erosion was simulated. The mechanism of bubble explosion could significantly contribute to the surface erosion at high ion fluxes and explain the existing experimental results.