Plasma Interactions and Sputtering Erosion for Plasma-Infused Volumetrically-Complex Surfaces*

Plasma material interactions are a challenge for lifetime and performance of plasma devices for applications such as fusion energy and electric propulsion. Recent advances in the development of robust surfaces for electrodes and plasma-facing surfaces for high energy-density applications at the UCLA Plasma & Space Propulsion Laboratory have shown that volumetrically-complex surfaces produce persistent sputtering yield reduction of 80% (Li et. al 2021). The objective of this work is to characterize the material sputtering behavior and bulk plasma response of plasma interactions with a range of volumetrically-complex surface geometries. Both plasma-infused and plasma-facing regimes are investigated using flat aluminum and kapton surfaces, and 10 and 40 PPI aluminum foams with different backing materials exposed to a xenon plasma. The angular sputtering yield, optical emission line intensity, bulk plasma potential, density, electron temperature, sample current, and temperature are all constantly measured over the 15 hour exposures. The measurements, along with comparison between different PPI foams and backing materials, provide insight on the impact the effect the plasma-facing versus plasma-infused regime plays on persistent sputtering yield reduction, plasma properties, and contamination.