Bulletin of the American Physical Society
73rd Annual Gaseous Electronics Virtual Conference
Volume 65, Number 10
Monday–Friday, October 5–9, 2020; Time Zone: Central Daylight Time, USA.
Session LT3: Poster Session III (4:30pm - 6:30pm)On Demand
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LT3.00001: NRL Evaluated Plasma Chemistry (nepc): a Python Package for Electron Scattering Cross Sections P.E. Adamson, A.S. Richardson, I.M. Rittersdorf, S.B. Swanekamp, D.J. Watkins, N. Krishnakumar The Naval Research Laboratory (NRL) evaluated plasma chemistry (nepc) Python package and associated MySQL database schema are prototype open source tools that support the use of electron scattering cross section data and metadata in plasma physics simulations. It provides access to pre-defined plasma chemistry models and some preliminary functionality for performing exploratory data analysis. The software supports incorporation of cross section data from common sources (e.g. LXCat) and augmentation of the data with additional metadata. The current capabilities and future directions of the Python package, including support for uncertainty quantification studies, will be discussed. [Preview Abstract] |
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LT3.00002: Electron Beam Irradiation of Personal Protective Equipment (PPE). Min Huang, Md Kamrul Hasan, Matt Pharr, David Staack, Suresh D. Pillai Given the pandemic of COVID-19, the healthcare market and the supply chain of PPE have been challenged all over the world. N95 Respirators, surgical masks and clothing gowns are most consumed and in serious shortage. To sterilize and reuse PPE is becoming an effective way to ease the poor situation. Electron beam has been used frequently with 4.5{\%} share in the global market. From this perspective, N95 Respirators (3MTM), Surgical mask, AAMI Gown, Activgard Gown, and polypropylene and polyester have been utilized as research objects. Doses (25kGy-200kGy) and irradiation medium (air, argon) have been varied to research irradiated samples mechanical and protective performance. Wettability testing, Yellowness Index (YI), SEM, and tensile testing have been utilized to research irradiated PPE. Hydrostatic Pressure and Impact Penetration testing have been used to study the liquid barrier performance of AAMI gown. So far, the results of all testings showed an ignorable difference in samples irradiated with sterilized level dose (15kGy-30kGy), while hydrostatic pressure and impact penetration testing shows samples irradiated with 200kGy appear to fail. Both the results from tensile testing of N95 Respirator and gown showed a decrease in mechanical performance. [Preview Abstract] |
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LT3.00003: Spatiotemporal characteristics of plasma structure induced by manipulation of electron cross-field transport in a Hall thruster Junhwi Bak, Rei Kawashima, Kimiya Komurasaki In ExB plasmas such as Hall thrusters and magnetrons, azimuthally propagating coherent structures, such as the rotating spokes, are commonly found. Because plasmas are typically generated from initially uniformly applied operating parameters and resulting from interactions between multiple species, it is often difficult to distinguish which species is responsible for a specific observed result. In this work, we artificially introduce azimuthal inhomogeneity in neutral particles and magnetic fields that strongly affect the magnetized electrons. By doing so, it can help to understand how manipulated parameters are related to observed plasma structures. With a high-speed camera, we investigate spatiotemporal characteristics of plasmas structure resulting from the altered electron flows and the relation between electron cross-field transport and self-formed plasma structure. In certain conditions, we observe a rotating spoke that clearly distinguishes itself from the ionization wave as it continues to rotate, leaving the localized enhanced ionization region behind. [Preview Abstract] |
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LT3.00004: Effect Of Dielectric Permittivity And Gas Pressure On Breakdown Voltage In Solid-Gas Systems. Igor Timoshkin, Mark Wilson, Martin Given, Scott MacGregor, Nelly Bonifaci, Rachelle Hanna The development of more energy efficient/more electric aircrafts require advanced electrical systems which should operate in challenging environmental conditions: lower air pressure, elevated humidity, a wide range of temperatures. Also, there is a growing interest in using elevated DC voltage levels in the electrical avionic systems in order to reduce conduction losses and to transmit increased levels of power. Thus, the higher voltage levels result in the requirement for the electrical wiring systems to be capable of operating at the high DC voltage levels. However, the lower air pressure leads to lower critical voltages at which gas discharge processes such as corona discharges can be triggered. The present paper investigates the electric field distribution in solid dielectric-gas (air) systems. The obtained electric field is used in the analysis of the safe operating voltages. The results presented and discussed in this paper can be used for insulation coordination, optimisation of spacing between energised and grounded components, and selection of suitable solid dielectrics for avionic electrical systems. Acknowledgement. This work is supported by The British Council-Alliance Hubert Curien Programme. [Preview Abstract] |
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LT3.00005: Contribution of Ion Distribution to Movement of Cathode Spot Affected by Amount of Metal Vapor in Vacuum Arc Masahiro Takagi, Yusuke Nemoto, Zhenwei Ren, Yoshifumi Maeda, Toru Iwao Vacuum arc has been applied for technology such as surface treatment of oxide layer, vacuum arc deposition. The vacuum arc produces a high-temperature, high-brightness cathode spot with high current density. It locally and instantaneously evaporates a cathode metal, and the metal vapor was ionized. The generated ions produce a high electric field near the cathode, which induces electron emission and forms a current path. This current path is deflected by the magnetic field and the cathode spot is considered to move. Therefore, it is necessary to understand the behavior of ions in the vicinity of the cathode spot. However, it is difficult to observe the motion of ions near the cathode spot experimentally because the cathode spot moves at a high speed. Therefore, contribution of ion distribution to movement of cathode spot affected by amount of metal vapor in vacuum arc was investigated by three-dimensional numerical simulation in this research. As a result, the cathode spot was moved because the moving direction of ions near the cathode was determined by electromagnetic force, then the ions were driven by force of pressure gradient, and current path was changed with varying time. [Preview Abstract] |
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LT3.00006: Arc Temperature Distribution with Metal Vapor Affected by Initial Breaking Arc Generation after Melting Bridge Using Three-Dimensional Electromagnetic Thermal Fluid Simulation Honoka Morishita, Shota Kokubo, Zhenwei Ren, Yusuke Nemoto, Yoshifumi Maeda, Takamasa Hayasaka, Toru Iwao Electric railway is supplied from a contact wire through a contact strip. When the contact wire and contact strip contact poorly, the arc generates and sometimes the contact wire is damaged and disconnected. For example, when the speed of the electric railway is reduced and the arc generates, the residence time of the arc may increase. Then, the disconnection may occur. The arc starts with the initial breaking arc after melting bridge between the contact wire and contact strip. In this time, the temperature distribution of arc and contact wire are important to avoid the contact wire disconnection. However, the arc generation is very fast phenomenon, and the measurement of contact wire temperature is very difficult. In addition, few reports have researched the temperature distribution of arc and contact wire from the evaporation and droplet from melting bridge. Thus, the temperature distribution of arc and contact wire with metal vapor generated by initial breaking arc after melting bridge is simulated by three-dimensional electromagnetic thermal fluid simulation. As a result, the temperature distribution is calculated, and it depends on the contacting arc time and the amount of the metal vapor from melting bridge. [Preview Abstract] |
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LT3.00007: Film Surface Treatment with O$_{\mathrm{2}}$/Ar Line Plasma under Atmospheric Pressure Haruka Suzuki, Hirotsugu Koma, Tomohiro Ogasawara, Manh Hung Chu, Hirotaka Toyoda Much attention has been given to application of non-thermal atmospheric pressure plasma (APP) to large-area surface treatment and development of a uniform and high-density large-scale APP device. So far, we have reported that a long-scale microwave APP (AP microwave line plasma: AP-MLP) with molecular gas is produced in a long slot on the waveguide wall by controlling electromagnetic power flow inside the waveguide to reduce standing waves. We reported spatially-uniform AP-MLP of \textasciitilde 100 cm in length using Ar or He and \textasciitilde 70 cm using N$_{\mathrm{2}}$ gas or O$_{\mathrm{2}}$/Ar admixture gas. In the case of \textasciitilde 0.1{\%} O$_{\mathrm{2}}$-admixed Ar, uniform O radical density of 1x10$^{\mathrm{13}}$ cm$^{\mathrm{-3}}$ in longitudinal length of 60 cm was observed. In this study, to demonstrate surface treatment processing, hydrophilic treatment of PET film surface is conducted using our plasma source with argon gas and its hydrophilicity and large-area spatial uniformity are evaluated. Furthermore, a few {\%} O$_{\mathrm{2}}$ is added to the argon microwave plasma and the film surface treatment is investigated. The hydrophilicity is improved in a relatively short time and the water contact angle is decreased with increasing the oxygen flow rate. The spatial uniformity of the processing is quite uniform in 20 cm. [Preview Abstract] |
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LT3.00008: Preliminary Results of Plasma Induced Hydrocarbon Reforming of Heavy Gas Oil (HGO) as part of an Ongoing Multiple Regional Heavy Crude Oil Field Sample Hydrocarbon Reforming Study. Jamie Kraus, Kunpeng Wang, Abdullah Baky, Christopher Campbell, Shariful Islam Bhuiyan, David Staack, Howard Jemison Heavy gas oil (HGO) was collected in the field upon exiting the vacuum distillation unit (VDU) before entering the HGO hydrotreater unit at a refinery. HGO is fed into a hydrotreater with other lighter gas oil constitutes to meet the feed requirements of the fluidized catalytic cracking unit (FCCU). The main product from the FCCU with hydrotreated HGO feed is gasoline-range hydrocarbons; however, unfavored products such as aromatics, residue, and coke are formed as a biproduct which rapidly diminishes the life span of the high capital cost catalyst within the FCCU due to fouling. Experiments were conducted with an induced nanosecond pulsed plasma spark in HGO with bubbling hydrogen-rich gas inside a designed and constructed oil treatment reactor (OTR) to investigate the high chemical conversion potential and commercial feasibility of hydrocarbon reforming of HGO using plasma technology with a full mass balance on the liquid, condensate, and solid constitutes. Preliminary results indicate the induced chemical reactions by plasma favor cracking and conversion of heavy diesel-range hydrocarbons into lighter gasoline-range hydrocarbons while increasing the cetane number in the treated gas-oil mixture and condensate with an unexpected high-yield of benzene. [Preview Abstract] |
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LT3.00009: Nonthermal Plasma Polymerization Coating on Aramid Surfaces for Durable Omniphobicity Eshraga A.A Siddig Durable superomniphobic textiles, including self-cleaning, protective clothing, and liquid separation, are beneficial for their practical applications. Nonthermal plasma polymerization of environmentally friendly C6 fluorine was coated, and a durable omniphobic aramid fabric was achieved. The fabric became water and oil repellent with an elevated static water contact angle of (\textgreater 170 \textdegree ). As tested by the water spray AATCC test and hydrocarbon resistance test, the as-prepared fabric gained 100\textdegree (ISO5) and grade number 4 respectively. Compared to directly coated aramid fabric, its water contact angle remained stable above 170\textdegree , and its AATCC water/oil repellent separately was two grades higher after 10 washing cycles display improved washing durability. Surface techniques indicated that the durable superomniphobicity can be related to the plasma introduction of reactive polar groups like O$=$C-O on the fibre surface, which induces more adsorption and chemical graft of the C6 copolymer. -keywords Nonthermal plasma polymerization; Aramid fabric; Superomniphobicity; Washing durability [Preview Abstract] |
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LT3.00010: Vertically Nanostructured Plasma Polymer Films Controlling Surface and Subsurface Functionality Dirk Hegemann, Ezgi Bulbul, Sandra Gaiser, Manfred Heuberger Deposition of plasma polymer films (PPFs) occurs via plasma activation of a monomer (here: hexamethyldisiloxane, HMDSO) yielding excited intermediates and conversion into highly reactive film-forming species. The conversion is given by the transferred energy depending on electron temperature and the available energy per monomer molecule in the gas phase, while surface processes are governed by the deposited energy during film growth. This mascroscopic approach was used to shed light on the deposition mechanism for HMDSO plasmas applied to control deposition rate, chemical composition, film density, porosity, and functionality at the nanoscale[1]. Hydrophobic nanolayers with defined density can be deposited on similar materials such as PDMS or SiOx fully covering their surface. 2 nm-thick hydrophobic cover layers on PDMS substrates of different crosslinking degree are used to clarify the role of viscoelastic properties on bacterial growth indicating the lack of mechanosensing abilities [2]. Likewise, hydrophobic cover layers with varying film density are explored to control water intrusion. Thus, barrier properties of dense SiOx films can be enhanced or a defined volume of water can be allowed to penetrate a porous SiOx base layer. Protein adsorption of BSA is found to be affected by this hydration effect due to orientation of water molecules in the subsurface [3]. Recent progress in the understanding of plasma polymerization processes thus enables the design of combined subsurface/surface functionalities.\newline [1] D. Hegemann, S. Gaiser, M.R. Wertheimer et al., Phys. Chem. Chem. Phys. 21 (2019) 8698 [2] F. Pan, D. Hegemann, E. Bülbül, Q. Ren et al., Mater. Horiz. 7 (2020) 93 [3] E. Bülbül, M. Heuberger, D. Hegemann et al., ACS Appl. Mater. Interfaces 11 (2019), 42760 [Preview Abstract] |
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