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 UR2: Modeling and Simulation: Breakdown and KineticsLive
|
Hide Abstracts |
Chair: Matthew Hopkins, Sandia National Laboratories NM |
Thursday, October 8, 2020 1:00PM - 1:15PM Live |
UR2.00001: Ionization Mechanisms in a Laser-Produced Plasma for Single Particle Aerosol Mass Spectrometers Amanda Lietz, Jeffrey Musk, Matthew Hopkins, Benjamin Yee, Harry Moffat, Dora Wiemann, Taylor Settecerri, Michael Omana Single particle aerosol mass spectrometers (SPAMS) are an emerging technology which can provide high sensitivity mass spectra for aerosols. For example, SPAMS could enable real-time measurements of pollution rather than collection on filters and processing in a laboratory. Obtaining mass spectra for individual particles rather than an average also provides more information than the average alone. In this presentation, the ionization mechanisms and plasma chemistry which occur in a SPAMS system are investigated using computational modeling. A 1 $\mu $m aluminum sphere is vaporized, and the resulting gas is ionized by a 248 nm laser with an 8 mJ, 8 ns pulse. The initial vaporization is investigated using a hydrodynamics model, and upon transition to gas phase, the plasma chemistry is modeled with a 0-dimensional model. It was found that pressure broadening can lead to direct absorption of laser photons, despite the laser wavelength being 9 nm from resonance with a transition. Photoionization of electronic excited states also plays a significant role. The effects of particle diameter and laser intensity on the ionization fraction and dominant ionization mechanisms are discussed. \textit{SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.} [Preview Abstract] |
Thursday, October 8, 2020 1:15PM - 1:30PM Live |
UR2.00002: Modeling of extreme ultraviolet emissions of molecular nitrogen induced by nonthermal gas discharges in air with application to photoionization and photodetachment processes in the Earth's lower ionosphere Reza Janalizadeh, Victor P Pasko Modeling the extreme ultraviolet (EUV) emissions of molecular nitrogen, N$_{2}$, induced by nonthermal gas discharges in air is yet an unsolved problem [Janalizadeh and Pasko, \emph{Plasma Sources Sci. Technol.}, 28(10), 105006, 2019]. These emissions cause photoionization of molecular oxygen, O$_{2}$, which significantly impacts streamer dynamics in air [e.g., Liu et al., \emph{J. Geophys. Res.}, 109, A04301, 2004]. Recently, Janalizadeh and Pasko [\emph{J. Phys. B}, doi: 10.1088/1361-6455/ab76e6, 2020] modeled the intense $(v'=0,v''=0)$ emission band of the N$_{2}$ Carroll-Yoshino band system (i.e., $c'_{4}{}^{1}\Sigma^{+}_{u}\rightarrow X{}^{1}\Sigma^{+}_{g}$) due to nonthermal gas discharges. Here, we expand our framework to include ${}^{1}\Pi_{u}\rightarrow {}^{1}\Sigma^{+}_{g}$ transitions, which along with ${}^{1}\Sigma^{+}_{u}\rightarrow {}^{1}\Sigma^{+}_{g}$ transitions govern the EUV spectrum of N$_{2}$. In particular, we consider the N$_{2}$ Birge-Hopfield I band system with emissions observed in the Earth’s dayglow and aurora [R. R. Meier, \emph{Space Sci. Rev.}, 58, 1-185, 1991]. In conclusion, the framework is discussed in relation to sources other than solar radiation, which may contribute to photoionization and photodetachment processes in the lower ionosphere. [Preview Abstract] |
Thursday, October 8, 2020 1:30PM - 1:45PM Live |
UR2.00003: Controlling Vibrational Excitation in Atmospheric Pressure Nitrogen Discharges Helen Davies, Andrew Gibson, Marjan Van der Woude, Timo Gans, Deborah O'Connell The influence of vibrational states is well-documented in low pressure nitrogen systems, in particular their role in nitrogen dissociation and ionisation, as well as mediating the appearance of the Nitrogen Pink Afterglow. However, their importance in atmospheric pressure discharges has generally been studied in less detail. Here, a 0D global model was used to investigate the effects of different plasma operating conditions on the vibrational excitation in simulated, pulsed, atmospheric pressure nitrogen plasmas. Power and frequency variations revealed that increasing energy input increases the population of vibrationally excited states in the plasma, allowing them to play important roles in the plasma chemistry, in particular with respect to metastable production. It is also shown that above a certain threshold of energy input, vibrational states act to store and redistribute energy in the system through vibration-vibration collisions. This occurs in a manner that is independent of whether this energy is input through a higher frequency or power, as long as the total energy is above the required threshold. Overall this work aids the understanding of atmospheric pressure chemical kinetics in nitrogen, and allows insights into potential tailoring of plasmas for applications. [Preview Abstract] |
Thursday, October 8, 2020 1:45PM - 2:00PM Live |
UR2.00004: Plasma Breakdown in Bubbles: Capturing Realistic Bubble Shapes using Direct Numerical Simulation Naveen Pillai, Igor Bolotnov, Katharina Stapelmann The ignition of plasmas in liquids has garnered a lot of attention in the past decade for applications ranging from usage in medical instrumentation to manipulation of liquid chemistry. While direct liquid ignition often requires prohibitively large electric fields to initiate breakdown, targeting streamer formation in bubbles submerged in a liquid with a higher permittivity can lower the requisite external field strength by an order of magnitude. This work utilizes 3-D direct numerical simulation (DNS) to simulate the precise bubble shapes formed in a full-scale model of our experimental setup. Due to the vast difference in timescales between fluid dynamics and plasma formation, plasma breakdown can be fully simulated within a single flow solution timestep. Thus, we use a 2-D plasma hydrodynamics model to capture the streamer behavior using static bubble geometry generated through the DNS code. In a frozen bubble just before collision with the powered electrode ($+$30 kV), we saw streamers propagating from the leading edge (closest to the powered electrode) to the trailing edge (closest to the ground). Preliminary computational results from a pin to pin setup with the same frozen bubble showed streamers propagating along the edge of the bubbles rather than through the body. [Preview Abstract] |
Thursday, October 8, 2020 2:00PM - 2:30PM Live |
UR2.00005: Breakdown in rf and dc fields Invited Speaker: Dragana Maric In this presentation new developments in measurements of the breakdown in radiofrequency fields will be presented together with results of Monte Carlo simulations that reveal physical causes for the features of breakdown curves, scaling and the importance of surface processes and of attachment of electrons will be examined. It has been found that in the two valued branch of the breakdown curve in one end electrons never reach region close to electrodes while for the higher voltages they dominantly collide with electrodes where they may disappear or be reflected. The nature of the dominant ionization is different in two branches. A new technique for the detection of the rf breakdown at low pressures, based on a balanced capacitive bridge will also be presented. The technique eliminates common problems in rf breakdown measurements and enables a precise time-domain tracking of the breakdown process. The presentation will be completed by the results of studies of dc breakdown and high E/N transport in alcohol vapors and in water vapor. Work done in collaboration with: Marija Pua\v{c}, Antonije \DJ or\dj evi\'{c}, Jelena Marjanovi\'{c}, Gordana Malovi\'{c} and Zoran Lj. Petrovi\'{c} [Preview Abstract] |
Thursday, October 8, 2020 2:30PM - 2:45PM Live |
UR2.00006: Blending machine learning and thermal engineering for plasma diagnostics: A predictive modeling study using plasmid DNA. Amal Sebastian, Sylwia Ptasinska Atmospheric pressure plasma (APP) is emerging as a potential candidate for numerous applications ranging from medicine to material processing. Due to many process parameters involved during the plasma interaction with the target, choosing the ideal parameter combinations for these applications is often challenging. The knowledge of reactive species delivery and thermal properties of plasma at each parameter is an inevitable key to solve this problem. The plasma-induced strand breaks and denaturation occurring in DNA can hint on the reactive species delivery and plasma gas temperature, respectively. We propose a supervised machine learning model to predict these plasma treatment-induced changes occurring in a plasmid DNA target. The predictive modeling was performed primarily using an artificial neural network (ANN) architecture, and a physical constraint based on treatment time was integrated into ANNs. The potential changes in the predicted strand breaks and denaturation with APP parameters were investigated. A novel methodology to deduce the plasma gas temperature by blending a heat transfer model and predictive model will be discussed. The optimal parameter choices that could be ideal for plasma medicine applications was proposed out from predictive modeling results. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700