Recent secondary electron modeling at Princeton Plasma Physics Laboratory

Over the past 5 years, researchers at Princeton Plasma Physics Laboratory (PPPL) have been engaged in research to theoretically characterize Secondary Electron Emission (SEE) from complex surfaces. We have used both a Monte Carlo numerical method and an analytic integral model to study the phenomenon. We have studied the specific shapes of velvet, foam, and a feather-like fractal surface using these methods, including parametric dependence (aspect ratio, packing density, angle of incidence). We have found that the Secondary Electron Yield (SEY) of a velvet surface can be significantly smaller (< 10%) than a flat surface, but only for electrons which are normally incident. We have found that the SEY of foam surfaces is much more isotropic with respect to angle of incidence, but that the minimum SEY does not approach that of velvet (~ 30%). Using the understanding gleaned from analysis of velvet, we proposed a primary velvet with a smaller secondary velvet grown onto it, which we called “feathered" because of its resemblance to down feathers. We have found that a feathered surface exhibits isotropic and dramatic SEY reduction.