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Download or read book DC Plasma Interactions with Structured Surfaces written by Cesar Eduardo Huerta and published by . This book was released on 2019 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma-material interactions (PMI), such as sputtering, electron emission, and deposition, play an important role in the evolution of surface geometry and its effects on the plasma and sheath properties for a wide range of plasma devices and applications. In the work presented herein, the effects of sputtering, deposition, and secondary electron emission are modeled in order to better understand these physical phenomena and the effect of surface structure on PMI. The sputtering model developed in this work accurately captures surface architecture effects via a computationally-efficient view factor model. The model reveals that increasing the surface pitch angle beyond about 45 can lead to significant decreases in the normalized net sputter yield for all simulated ion incident energies (i.e. 75, 100, 200, and 400 eV) for both smooth and roughened surfaces. At higher incident energies, smooth triangular surfaces exhibit a nonmonotonic trend in the normalized net sputter yield with surface pitch angle with a maximum yield above unity over a range of intermediate angles. The resulting increased erosion rate occurs because increased sputter yield due to the local ion incidence angle outweighs increased deposition due to the sputterant angular distribution. For nano-rod surfaces, the model captures the coalescence of sputterants at the protuberance sites and accurately illustrates the structure's expansion due to deposition from surrounding sputtering surfaces, thus demonstrating the capability to aid in developing favorable surface applications for plasma applications. Similarly, a particle pushing model is used to investigate secondary electron emission for varying effects of complex surfaces by using simple geometric constructs. Geometries used in the model include: vertical fibers for velvet-like surfaces, tapered pillars for carpet-like surfaces, and a cage-like configuration of interlaced horizontal and vertical fibers for nanostructured fuzz. The model shows that unlike other structured surfaces previously studied, tungsten fuzz exhibits secondary electron emission yield that is independent of primary electron incidence angle, due to the prevalence of horizontally-oriented fibers in the fuzz geometry. The PMI physics simulated in these models are implemented into a DC discharge plasma model, DC-ION. Along with these additions, the code is improved and modified to simulate a canonical plasma column incident on a variable anode surface. Simulation results are compared with experimental data obtained for an aluminum slab surface, as well as two aluminum foams with different porosities. Simulation results show good agreement with the experimental data and agree with analytical expectations of the impact that architectured surfaces have on the plasma. These results show that these featured surfaces are the promising candidates for improving a wide range of plasma devices, including electric propulsion, laboratory plasma sources, and high-temperature fusion devices.