<b>EXPERIMENTAL CHARACTERIZATION OF ADDITIVELY MANUFACTURED MATERIALS FOR ELECTRIC PROPULSION SYSTEM APPLICATIONS</b>

<p dir="ltr">This article explores the sputtering mechanics of additively manufactured (AM) 316L stainless steel, and the integration and operational feasibility of AM W24Re grids in an electrostatic gridded ion source. Basic and preferential sputtering mechanics are briefly discussed to explain expected behavior of the 316L samples and grids.</p><p dir="ltr">Three 316L bulk material samples were exposed to the beam of a KDC-40 electrostatic gridded ion source at three distinct energy levels of 400, 600, and 800 eV on each side of the sample for a duration of one hour. The samples were masked to create a distinct boundary between treated and untreated regions, identifiable using profilometry, and were biased to -18V for testing. Samples were then examined using a Bruker optical profilometer and further processed using the open-source software Gwyddion to evaluate the sputtering yield. The suppering yield varied in the range 0.2-2 atoms/ion for 400-800 eV ions and increased with ion energy. The measured sputtering yield was fairly consistent with Yamamura theoretical predictions, while exhibiting a steeper sputtering yield increase with ion energy, with some variations potentially due to added effects of increased temperature or oxide sputtering. These results were consistent with previous findings by Roth <i>et al</i> that indicate increased sputtering of 316L stainless steel with increased temperature. Future work is recommended to include changes to experimental setup to ensure higher accuracy, and analysis of surface concentration data to better support preferential sputtering analysis.</p><p dir="ltr">The AM W24Re grids were fabricated and assembled in the KDC-40 gridded ion source instead of original grids to ensure good fitment. Operational feasibility was successfully demonstrated in the short tests with durations of up to 17 minutes. Longer term testing on the order of several hundred hours would be required to fully prove operational feasibility and sputter characteristics. Additional consideration should be given to the grids’ construction to make them easily swapped replacements for the original grids in a system.</p>