Image caption: Plasma foams created by the Wirz Research Group. Inset photos L-R: Dr. Gary Li; Prof. Richard Wirz. Image credit: Wirz Research Group.
Scientists and engineers have long searched for materials that can contain hot plasmas. Recently, researchers in the Wirz Research Group at UCLA have published results in Physical Review Letters that show metallic foams might be the answer.
While exposing metallic foams to hot plasma for over 30 hours, they discovered that the foam would “bend but not break” under the intense plasma conditions. In fact, the showed that the foam persistently reduces the erosion caused by the plasma up to over 80% compared to flat materials.
During these tests, they also discovered that the plasma can infuse into the pores of the foam – leading them to identify a new multi-phase material called “plasma-foams”. As shown in the image, the foam is exposed directly to a high-energy plasma column.
In the process of their investigation, they characterized a new parameter to help describe plasma foams. This parameter is called “plasma-infusion” and is a measure of the degree to which the plasma infuses into the foam. Specifically, it is defined as the ratio of the average foam pore diameter and the plasma’s sheath thickness.
Since these new plasma-foam materials are uniquely robust to hot plasmas, they present exciting opportunities to improve the life and performance of future plasma devices for applications such as manufacturing, aerospace and hypersonic vehicles, space propulsion, and fusion energy.
The work was led by Prof. Richard Wirz, mechanical and aerospace engineering professor and Director of the Plasma & Space Propulsion Laboratory and Energy Innovation Laboratory at UCLA. The lead author is NDSEG Fellow Dr. Gary Li who recently earned his Ph.D. from Prof. Wirz’s research group and now works at The Aerospace Corporation in El Segundo, California. The research was funded by multiple grants from the U.S. Air Force Office of Scientific Research.
Reference: Li G., Wirz R.E., “Persistent Sputtering Yield Reduction in Plasma-Infused Foams,” Physical Review Letters, 126 (3), 035001 (2021) https://doi.org/10.1103/PhysRevLett.126.035001