Accurate Numerical Models of the Secondary Electron Yield from Grazing-Incidence Collisions

72158 Interactions with unwanted electrons are a major limiting factor in the performance of ion accelerators. A main source of these electrons is collisions at grazing incidence between ions and beam pipe walls. Computer modeling could be used to examine this problem, but the codes in the heavy-ion fusion community presently do not have the capability to accurately model grazing-incidence collisions. We will develop a complete package of accurate numerical models of grazing-incidence collisions between ions and walls. This package will include tables of data from a well-known ion-material interaction code, and it will include development of a new ion-material interaction code. The final package will give heavy-ion fusion simulation codes the ability to determine ways to mitigate the effects of unwanted electrons. A model of surface roughness was implemented in an ion-material interaction code, a model of electron yield was derived from that rough surface model, the electron yield model was validated against experimental results, the electron yield model was combined with a well-known particle tracking code, models of ion scattering were developed based on ion-material interaction simulations, models of electron yield were developed including ion scattering, and a new code was prototyped to calculate electron yield from ion-material interaction. Tables of data will be created for ions, materials, energies and angles important to heavy-ion fusion and the routines to access that data, ion scattering will be added to a new ion-material interaction code to better model grazing collisions, rough surface models will be added to that same code, and finally autotools, steering with a popular scripting language, graphical user interface and computer-aided design features will be added to make building and using the code easy. Commercial Applications and Other Benefits as described by awardee: There are two important commercial aspects to this work: (i) an improved ion-material interaction code has applications in the health care industry, and (ii) expertise in electron effects has potential for consulting work in the accelerator industry.