Optimization of Polishing Techniques to Reduce Foil Thickness Variation.

Thin foils of Beryllium (Be) and Depleted Uranium (DU) are used in detection applications for plasma and radiation experiments. To improve foil performance, a new standard method for polishing foils was created to reduce thickness variation to $+$/-2 $\mu $m and produce repeatable foil thicknesses. Using non-hazardous metals as surrogates to Be and DU, the results from increased automation and varying polishing times {\&} pressures were compared against previous methods, whose thickness variation neared $+$/-10 $\mu $m. Metal foils of Aluminum (Al), Tin (Sb), Silver (Ag) and Gold (Au) with diameters from 3 mm to 12.5 mm were polished to target thicknesses of 5 $\mu $m, 10 $\mu $m, and 40 $\mu $m. Topographies of the foils were inspected to determine reproducibility of thickness variation within specification using Dual Confocal Microscope (DCM) imaging and White-light Interferometry Microscope (WIM) imaging.