Bulletin of the American Physical Society
74th Annual Gaseous Electronics Conference
Volume 66, Number 7
Monday–Friday, October 4–8, 2021;
Virtual: GEC Platform
Time Zone: Central Daylight Time, USA
Session HW14: Plasma-surface Interactions II |
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Chair: Shaun Smith, Lam Research Room: Virtual GEC platform |
Wednesday, October 6, 2021 8:00AM - 8:15AM |
HW14.00001: Molybdenum Erosion in an Hollow Cathode-like Iodine Plasma Enviroment James D Rogers, Richard Branam The maturation of electric propulsion technology has led to an increased interest in replacing Xenon as the propellant of choice. Iodine is an attractive alternative to Xenon, due to its similar performance characteristics, improved storage capabilities, and dramatically lower price. However due to its nature as a halogen, iodine is very reactive and presents serious challenges for the lifespan of plasma facing materials. The most critical component of a typical electric propulsion system is the hollow cathode due to the high plasma densities and wall temperature required for operation. |
Wednesday, October 6, 2021 8:15AM - 8:30AM |
HW14.00002: Investigation of a spatially resolved open microchannel substrate using a He/Ar APPJ Josh Morsell, Kseniia Konina, Sanjana Kerketta, Astrid L Raisanen, Mark J Kushner, Steven Shannon Atmospheric pressure plasmas are of great interest due to their applications in surface modification, medicine, and advanced manufacturing. There is still much to learn about these plasma systems, including how plasmas interact with complex and multiphase surfaces. The goal of this work is to use an open microchannel substrate utilizing capillary flow to investigate the spatially resolved generation of hydroxyl radicals perpendicular to the plasma impinging on the substrate. This configuration provides a controlled delivery of liquid for plasma exposure to quantify interaction through plasma diagnostics and post exposure liquid treatment. The open microchannel substrate allows for flow control of 0.35$ml/min$ to 1.2$ml/min$. Channels have a rectangular cross-section of 100$\mu m$ wide and 200$\mu m$ in depth with a pitch of 100$\mu m$. Gas phase investigations include gas temperatures via $N_{2}$ and state densities of argon. Plasma is generated using an APPJ with two power delivery configurations: 1.) 13.56$MHz$ RF and 2.) pulsed high voltage DC, using a He/Ar mixture with varying flow rate. The goal of this study is to quantify the power delivery of the plasma to the substrate as well as quantify the plasma interactions with the solid and liquid area of the substrate. |
Wednesday, October 6, 2021 8:30AM - 8:45AM |
HW14.00003: Multielectron reactions at the plasma-air/water interface Alexander G Volkov There are three major multi-electron reactions in nature: nitrogen fixation by bacteria, water oxidation in photosynthesis, and oxygen reduction during respiration. Industrial fixation of molecular nitrogen in the Haber-Bosch process is very expensive and requires extremely high temperatures and pressures. Here we found that cold atmospheric pressure He-plasma jet (CAPPJ) can oxidize N2 to HNO3 and HNO2 at low temperature and atmospheric pressure at the plasma/water interface. Analysis of the images showed that redox reactions occur at the plasma-air/water interface and the products of electrochemical reactions slowly diffuse into the bulk of the aqueous solution. Acidification of an aqueous solution during the CAPPJ treatment correlates with an increase in HNOx concentration in the aqueous phase. HNO2 is unstable and can be oxidized to HNO3 by plasma-generated H2O2 or ozone. The mechanisms of the interfacial multielectron reactions at the plasma-air/water interface are discussed and evaluated. Plasma-induced production of HNOx at the plasma/water interface at room temperature and atmospheric pressure can be used in the industry for nitrogen fixation and production of nitrogen compounds, replacing the expensive old technology processes. Plasma-activated water can be used in medicine and agriculture for disinfection, sterilization, and decontamination. |
Wednesday, October 6, 2021 8:45AM - 9:00AM |
HW14.00004: An efficient autoencoder neural network plasma-surface interaction model for sputtering processes Tobias Gergs, Borislav Borislavov, Jan Trieschmann Comprehensive low-temperature plasma processing models require an accurate physical description on all time and length scales of the plasma discharge, the plasma transport and the plasma-surface interactions. In this work, we revise a machine learning plasma-surface interface surrogate model for bridging the inherent scales with a high physics-fidelity regression model at modest computational cost, to address the excessive number of considered degrees of freedom. To establish a physical description of mixed material sputtering, the impingement of Ar ions onto Ti-Al composites is studied in this work for varying stochiometries by means of Monte Carlo surface simulations. The obtained data is compressed into a low-dimensional latent space representation by utilizing a variational autoencoder neural network. Thereafter, a comprehensive regression is realized by using a dedicated mapper network and transfer learning of the previously trained decoder network. Excellent generalization is demonstrated, enabling effective denoising of statistically varying data samples and physically sound interpolation even for not previously trained stoichiometries and incident ion energies. |
Wednesday, October 6, 2021 9:00AM - 9:15AM |
HW14.00005: VUV-Photoionisation Chamber for the Characterization of Ion-Substrate Interactions at Atmospheric Pressure Kerstin Sgonina, Alexander Quack, Christian Schulze, Tristan Winzer, Leonie Mohn, Jan Benedikt The strong interaction between cold atmospheric pressure plasmas and biological substrates is, besides the reactive oxygen and nitrogen species, also based on additive or synergistic effects of these reactive species with charged species, photons, and electric fields. In contrast to photons or electric fields, the study of the isolated effect of ions with biological substrates is more challenging as their solely production under atmospheric pressure is not trivial. To prove the expected enhanced effect of ions due to their charge and internal energy, knowledge about the ion composition and absolute ion fluxes to the substrate is needed. |
Wednesday, October 6, 2021 9:15AM - 9:45AM |
HW14.00006: Effects of Sputtering, Re-deposition and Diffusion Processes for Helium Plasma Induced Metal-nanostructure with Multi-hybrid Simulation Analysis Invited Speaker: Atsushi M Ito Fuzzy metal nanostructure, called “fuzz”, induced by low energy helium plasma irradiation was found in the experiment on a plasma-facing tungsten material used for the inner wall of plasma vacuum vessels. To form a fuzz, the helium irradiation energy should be less than about 100 eV and the total helium fluence should be greater than 1024 m-2s-1. We have been investigating the formation mechanisms of the fuzz using molecular simulations. From those conditions of fuzz, we aimed for a simulation that achieves a long-term scale equivalent to an atomic experiment while keeping the spatial scale at the nanoscale. |
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