A laboratory study found that the reported sputter yield of additively manufactured 316L stainless steel increased with ion energy. In a separate part of the work, additively manufactured tungsten-rhenium grids were integrated into a KDC-40 gridded ion source and operated during a short test.
The work concerns sputtering and component integration in one laboratory setup. The short grid test does not establish long-term erosion resistance or service life; longer tests were required to quantify erosion.
The steel measurements rose with beam energy
Across the tested range, the reported sputter yield for the printed 316L steel ranged from 0.2 to 2 atoms per ion for ions with energies from 400 to 800 electron volts. The measurements followed an upward trend as beam energy increased.
The researchers used three additively manufactured 316L stainless-steel samples. Each was exposed to the KDC-40 ion beam at 400, 600 and 800 electron volts on each side for one hour, with the samples biased to minus 18 volts.
The team used a molybdenum mask to leave an untreated reference area beside the exposed region. A Bruker GT-K optical profilometer and Gwyddion were used to derive the step height and etch rate, with each test-site data point based on at least two images.
The yield calculation used a target density of 8,000 kilograms per cubic metre and a target atomic mass of 56.515 atomic mass units. The density was calculated from mass divided by volume, while the atomic mass was obtained from a weighted average of the material’s components.
Build-direction and build-plane readings
For surfaces aligned with the build direction, most measurements at 400 electron volts were between 0.21 and 0.73 atoms per ion and below model predictions. At 600 electron volts, readings were 1.00 to 1.26 atoms per ion and closer to the predictions. At 800 electron volts, most readings were 1.49 to 1.94 atoms per ion and above them.
Build-plane measurements followed the same general energy trend. At 600 electron volts, one group measured 0.82 to 0.88 atoms per ion, while two higher readings were 1.4 and 1.5 atoms per ion. At 800 electron volts, most values were 1.42 to 1.65 atoms per ion.
The authors reported that the sputter yield of additively manufactured 316L was fairly consistent with traditionally manufactured material. That comparison was not based on a conventional-material control tested at the same time.
Printed grids operated for a short period
The second part of the work examined tungsten-rhenium grids made by metal 3D printing. The grids contained 76% tungsten and 24% rhenium, replicated the original grids and were integrated after minor assembly modifications.
All three additively manufactured tungsten-rhenium grids were used in the assembled ion optics. The full system had a cumulative testing duration of one hour, and stable operation was reported, although more stability issues were reported at lower beam energy.
Scanning electron microscope images taken before and after the short series of tests showed no substantial morphological changes in the grids. Longer-duration tests were required to quantify erosion.
The measurements leave important questions open
Several conditions could have affected the steel measurements. Neutralizer operation presented issues, beam-current density was not available in situ for every individual test, and sample temperature was not controlled or monitored during exposure. Later tests were expected to exceed 260 degrees Celsius in some cases. Sample curvature also affected the profilometer measurements.
Individual readings were averaged across scans, uncertainty was propagated through the sputter-yield equation, and an uncertainty-weighted average was reported across sides and samples. The analysis did not report inferential statistical tests or formal confidence intervals for the main comparisons.
The evidence is limited to laboratory measurements from three additively manufactured 316L blocks and short-duration operation of three additively manufactured tungsten-rhenium grids in one KDC-40 setup. It supports measured behavior in this apparatus, not a general conclusion across additive-manufacturing processes, materials, ion sources or operating lifetimes.
The project was supported by NASA Small Business Innovation Research award 204084 to Quadrus Corporation, which provided the additively manufactured stainless-steel samples and tungsten-rhenium grids. The supplied metadata identifies the manuscript as an arXiv preprint, while the extracted front matter does not state a journal or repository publication status.
Paper data and sources
Original title: Experimental Characterization of Additively Manufactured Metallic Alloys for Electric Propulsion Applications
Authors: J. Chamberlain, A. Shashurin
Journal/Repository: arXiv
Status: Preprint, not yet peer-reviewed
First online: 2026-08-26
DOI: Not available
Original paper · Full text