Bulletin of the American Physical Society
75th Annual Gaseous Electronics Conference
Volume 67, Number 9
Monday–Friday, October 3–7, 2022;
Sendai International Center, Sendai, Japan
The session times in this program are intended for Japan Standard Time zone in Tokyo, Japan (GMT+9)
Session FT3: Modeling - High Pressure and Streamers |
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Chair: Loius Reboul, CMAP, Ecole Polytechnique Room: Sendai International Center Shirakashi 1 |
Tuesday, October 4, 2022 1:30PM - 1:45PM |
FT3.00001: Efficient preconditioning for the simulation of nanosecond discharge using Jacobian-Free Newton Krylov Methods Alfredo J Duarte Gomez, Nicholas Deak, Fabrizio Bisetti A novel methodology is presented for the simulation of streamer discharges. The governing equations consist of the drift-diffusion model with local-field approximation, which is applied for the transport of all charged species. Electrons, one positive ion, and one negative ion are considered along with a simplified air-plasma chemistry that includes ionization, recombination, attachment, and detachment processes. Nonlinear boundary conditions with secondary emissions are also included. The governing equations are integrated in time in a fully coupled manner with the use of a Jacobian Free Newton Krylov (JFNK) method and a third-order implicit formulation. A suitable preconditioning framework based on operator splitting is developed and applied towards axisymmetric pin-to-pin discharge simulations in atmospheric air. The solver is implemented in parallel with the Portable Extensible Toolkit for Scientific Computation (PETSc). The governing equations are integrated successfully using time steps of up to 20 picoseconds and mesh resolutions of up to 0.6 micron, exceeding drift and dielectric time scales. The preconditioner was found to be very effective as shown by metrics, which include Newton iterations, Krylov iterations and wallclock times. |
Tuesday, October 4, 2022 1:45PM - 2:00PM |
FT3.00002: Electron dynamics and the mode-transition of a non-neutral discharge regime of the COST jet Maximilian Klich, Sebastian Wilczek, Ralf Peter Brinkmann In contrast to low-pressure plasmas, where the Debye length λD and the discharge length L differ by several orders of magnitude, many atmospheric pressure plasmas inherit comparable scales for these quantities. As a result of this characteristic, atmospheric pressure plasmas can fail to develop a quasi-neutral bulk region and operate in a non-neutral discharge regime. In previous work, we have shown that the electrons in this regime become organized in a soliton-like structure. Moreover, this Gaussian-shaped group of electrons organizes according to its center of mass (COM). This COM is in Boltzmann equilibrium, and its dynamics determine the electron dynamics as a whole. An unanswered question arising from analyzing the non-neutral regime is about its mode transitions and boundaries. The main goal of this work is to answer this question. We apply a one-dimensional hybrid particle-in-cell/Monte Carlo collisions (PIC/MCC) simulation simulating the electrode gap of the COST jet's cross-section. The influence of varied parameters (e.g., the applied voltage or the driving frequency) on the non-neutrality of the discharge is reported. Furthermore, this work pays special attention to the influence of the parameter-variation and mode transition on the electron dynamics. |
Tuesday, October 4, 2022 2:00PM - 2:30PM |
FT3.00003: Modeling of chemical reaction processes induced by an atmospheric-pressure streamer discharge in air Invited Speaker: Atsushi Komuro Streamer discharge is a fundamental process of atmospheric-pressure plasma, which produces high chemical reactivity field in the interelectrode space and on the material. The physicochemical processes occurred in streamer discharges is a key to understand the degree of the chemical reactivity and to control the atmospheric-pressure plasma for industrial applications. However, the streamer discharge is spatially steep and temporally fast phenomenon, it is difficult to measure the characteristics of the streamer experimentally. In this situation, the numerical simulation could be a powerful tool for the study. This paper presents the recent works for analyzing the physicochemical processes in atmospheric-pressure streamer discharges using simulations and experiments [1, 2]. For comparison, an axisymmetric single-filament streamer is generated in atmospheric-pressure air and compared with 2D simulation [2]. The propagation, emission intensity, shape, cathode current and ozone density of the single-filament streamer are compared with the results of the 2D simulation performed under conditions similar to those of the experiments. A marked difference between the experiments and simulation was the appearance of an intense streamer in the simulation. If the discharge starting voltage was decreased in the simulation, the intense streamer was significantly decreased but simultaneously the primary streamer velocity was decreased and deviated from the measured value. The simulated ozone density showed good agreement with that of the measurement except the ozone production in the intense streamer. |
Tuesday, October 4, 2022 2:30PM - 2:45PM |
FT3.00004: Design of a Microwave Plasma Enhanced Chemical Vapor Deposition System Using the Fluid Modeling based on the Finite Element Method Kaviya Aranganadin, Yilang Jiang, Jing-Shyang Yen, Jwo-Shiun Sun, Hua-Yi Hsu, Ming-Chieh Lin Microwave Plasma Enhanced Chemical Vapor Deposition (MPECVD) is one of the commonly used thinfilm manufacturing methods for diamond, graphene, etc. In an MPECVD system, the plasma consisting of ionized gas species and electrons is ignited and sustained by applying microwave, where a thin film can be deposited at lower temperatures. This paper discusses the design of a 3-D MPECVD chamber operated at a 2.45 GHz of frequency using the fluid modeling based on finite element method (FEM) that incorporates many physical interfaces such as laminar flow, heat transfer in fluids, plasma, and electromagnetic waves to give more self-consistent and accurate simulation results. The plasma discharge is modeled by coupling drift-diffusion, heavy species transport, and electric fields into a single multiphysics model. The conservation of mass and momentum are modeled in simulation by solving continuity and Navier-strokes equation, respectively. The geometrical design of MPECVD consists of a coaxial waveguide connected by slots to a cylindrical plasma chamber at the center to produce TM011 mode. At an input power of 1 kW with the argon pressure varied from 600 to 1500 Torr, the plasma density increases from 2.35e17 to 4.34e17 1/m^3 reaching steady-state at around 0.1 seconds and a uniform argon plasmas are excited by the TM011 microwave resonance. Detailed analysis of the dependence of the MPECVD operation on different pressures and input powers will be presented. |
Tuesday, October 4, 2022 2:45PM - 3:00PM |
FT3.00005: Development of Three Dimensional Thermofluid Model for Ar-O2 Loop Induction Thermal Plasmas with Reaction Rates for Dissociation of O2 on the Substrate Tomoya Fuwa, Hiroya Hara, Yasunori Tanaka, Yusuke Nakano, Tatsuo Ishijima, Tetsuya Yukimoto, Hiroshi Kawaura In this report, a three-dimensional thermo-fluid model of an Ar/O2 loop inductively coupled thermal plasma (Loop-ICTP) was developed to investigate the dissociation reaction of oxygen molecules as well as heavy-particle temperature, electron temperature, gas flow fields inside the torch and on the substrate surface. The Loop-ICTP is generated in a loop-shaped quartz tube sandwiched between circular coils . Then, a part of the Loop-ICTP is maintained with a long linear shape on the substrate. Afterwards, scanning the substrate perpendicularly to the linear plasma, the whole substrate surface area can be exposed by the plasma for two-dimensional (2D) surface modification . To understand the physical state of such Loop-ICTP in detail, numerical simulation is very useful. Results showed that increasing coil current value elevates the heavy particle temperature and the mass fraction of oxygen atoms effectively at the substrate surface. This suggests the possibility of fast oxidation of substrate surfaces by setting the adequate current value. |
Tuesday, October 4, 2022 3:00PM - 3:15PM |
FT3.00006: Massively parallel high-fidelity simulations of plasma-assisted ignition of hydrocarbon fuels using nanosecond pulsed discharges Nicholas Deak, Alfredo J Duarte Gomez, Lucas Esclapez, Marcus Day, Fabrizio Bisetti A series of numerical studies are conducted using the adaptive mesh refinement (AMR) compressible reactive flow solver PeleC, built on the AMReX software infrastructure, to investigate the ignition and propagation of axisymmetric atmospheric air streamers. A range of conditions and configurations are explored to better understand the streamer, with an emphasis on the cathode sheath region, which supports steep gradients in charged species number densities as well as strong electric fields. The formation of the cathode sheath is shown to be a consequence of processes at the cathode surface, driven by electron losses at the boundary, and a strong dependence on the emission of secondary electrons. Next, a reduced version of the mechanism is used to carry out axisymmetric pin-to-pin simulations of ethylene/air ignition. In each simulation, a series of NSPD are delivered to the gap through the application of a time-varying voltage to the anode until an ignition event occurs. It is observed that the highest temperatures and radical populations during the initial pulse are located near the electrode tips. A range of pulsing parameters are explored in order to assess the ideal conditions for rapid ignition and stable combustion. It is found that there is only a minor dependece of active particle creation on pulse frequency, with lower frequencies leading to greater populations of active particles. |
Tuesday, October 4, 2022 3:15PM - 3:30PM |
FT3.00007: Modelling and experimental studies of dielectric barrier discharges in dry and humidified air at sub-atmospheric pressure Marjan Stankov, Sergey Gortschakow, Markus M Becker, Robert Bansemer, Klaus-Dieter Weltmann, Detlef Loffhagen The processes leading to the generation of reactive oxygen and nitrogen species (RONS) and hydrogen-containing species (HCS) in dielectric barrier discharges in dry and humidified air were studied both experimentally and by numerical modelling. The plasma was driven by a sinusoidal voltage with a frequency of 24 kHz at a gas pressure of 100 mbar in the case of dry air. For humidified air a 30 kHz signal was used at a gas pressure of 200 mbar. For the determination of RONS in dry air and additionally HCS in humidified air with relative humidity (RH) values between 0.2 and 84%, FTIR spectroscopy measurements were employed in the downstream region of the discharge. The experimental analyses were accompanied by modelling of the particle number densities. In addition to the electron component, the global plasma-chemical model for dry air involves 50 heavy particle species. The modelling results reveal the importance of different production and loss processes of RONS as well as the influence of the gas temperature and the residence time of plasma in the discharge region on the particle number densities. In the case of humidified air, the model for dry air was extended by 29 HCS. It is found that except for O3, the number densities of the RONS and HCS increase with increasing RH value. |
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