Bulletin of the American Physical Society
63rd Annual Meeting of the APS Division of Plasma Physics
Volume 66, Number 13
Monday–Friday, November 8–12, 2021; Pittsburgh, PA
Session JO08: Low-Temperature Plasma Science, Engineering and TechnologyOn Demand
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Chair: Alexandros Gerakis, Luxembourg Inst of Science and Technology Room: Rooms 317-318 |
Tuesday, November 9, 2021 2:00PM - 2:12PM |
JO08.00001: A detailed collisional radiative model for diagnostics of the argon plasma using Ar and Ar+ emission lines Rajesh Srivastava, Neelam Shukla, Reetesh K Gangwar In many high-density argon plasma along with its emissions lines, significant emissions from higher ionic states of Ar, particularly from Ar+, are also observed . It would be interesting to carry out plasma diagnostics using both the emitted Ar and Ar+ lines by developing a reliable CR model. An extensive collisional radiative model is developed which consists of 42 fine-structure levels of Ar and 114 fine-structure levels of Ar+. Mechanisms such as electron-impact excitation/de-excitation, electron-impact ionization, radiation trapping, diffusion, two-body, and three-body recombination are incorporated [1]. A complete set of fully relativistic electron-impact fine structure excitation cross-sections linking different excited levels in Ar and Ar+ are included. We applied our model to characterize the Helicon plasma through its optical emission measurements reported by [2]. The key plasma parameters such as electron density and electron temperature using the Ar and Ar+ lines are obtained and compared with experimental predictions[2]. |
Tuesday, November 9, 2021 2:12PM - 2:24PM |
JO08.00002: Modeling Microsecond Timescale Molecular Formation in Laser Ablated Plasma Plumes Mikhail S Finko, Davide Curreli, Jonathan C Crowhurst, Wesley J Keller, Aric C Rousso, David G Weisz, Harry B Radousky, Kim Knight In recent years, laser ablation has seen increased use as an analytical tool for studying the chemical kinetics of metallic vapor in reactive atmospheric environments, primarily using laser induced breakdown spectroscopy (LIBS). However, interpretation of LIBS experiments is often hampered by the transient and nonuniform nature of the plasma plume expansion, which includes mixing and complex inner plume dynamics. Here, we present a one-way coupled model that connects early timescale (nanosecond) laser deposition and shock expansion physics to longer timescale (microsecond) plume evolution dominated by multispecies diffusion and chemical reactions. The initial expansion is compared to high-resolution optical plume imaging and time of flight measurements, while later molecular formation is compared against various literature studies. Aluminum ablation in air is used as the primary validation target, but other target materials are also discussed. |
Tuesday, November 9, 2021 2:24PM - 2:36PM |
JO08.00003: Charged particle acceleration and mass separation by oscillating electromagnetic fields Amnon Fruchtman, Gennady Makrinich Usually, under forces by the electric and magnetic fields of a uniform-in-space travelling wave, the velocity and energy of charged particles oscillate with no net energy exchange. However, if the phase between the electric and magnetic field is as in standing waves, charged particles can be accelerated. Such a secular term of the particle velocity evolves in a magnetized plasma, when an additional steady magnetic field is present, but also in an un-magnetized plasma, in the absence of such a steady field. In both magnetized and un-magnetized plasma, the direction of acceleration is mass dependent. In a collisional plasma, the acceleration becomes a drift, and the drift velocity decreases with the collision frequency. Interestingly, the direction of that drift velocity is also mass dependent. Alfven standing waves can be used for this process. Possible implications of these processes are in electric propulsion for space vehicles and for plasma mass separation. |
Tuesday, November 9, 2021 2:36PM - 2:48PM |
JO08.00004: Magnetic reconnection propulsion Fatima Ebrahimi A new concept for the generation of thrust for space propulsion, an Alfvenic reconnecting plasmoid thruster, is introduced (featured article in the Journal of Plasma Physics, Volume 86, Issue 6, December 2020). Energetic thrust is generated in the form of plasmoids or jets when magnetic helicity is injected into an annular channel. Using a novel configuration of static electric and magnetic fields, the concept utilizes a current-sheet instability to spontaneously and continuously create plasmoids via magnetic reconnection. The magnetic reconnection process here converts magnetic energy of the applied fields to kinetic energy of the plasmoids, accelerating them to a velocity of tens to hundreds of km/s, adjustable by varying the magnetic field strength. This concept combines magnetic helicity injection with axisymmetric fast magnetic reconnection, and is extensively explored via three-dimensional extended MHD NIMROD simulations. The plasmoids carry large momentum, leading to a thruster design capable of producing thrusts from tenths to tens of newtons. This thruster would occupy a complementary part of parameter space with little overlap with existing thrusters, and be suitable for high Delta-v missions, including the solar system beyond the Moon and Mars. Work supported by DOE. |
Tuesday, November 9, 2021 2:48PM - 3:00PM |
JO08.00005: Thrust Generation in the Center of Wall-less Hall thrusters Jacob Simmonds, Yevgeny Raitses Wall-less Hall thrusters contain large diverging axial magnetic fields in the center, with magnetic field gradients strong enough to confine electrons through magnetic mirroring [1,2]. Recent measurements of the plasma potential in this region of diverging magnetic field have shown potentials as high as the applied anode voltage, with electric field profiles similar to that in the acceleration region near the anode [2]. Measurements suggest an appreciable portion of the thrust is generated in the center, with thrust densities similar to that in the anode acceleration region. Given that the central electric fields are generated along the magnetic field lines and are larger than the plasma pressure gradient, the mechanism of formation of a large component of this electric field is unclear. However by utilizing electron energy anisotropy levels found in particle in cell simulations, we calculate an electric field due to magnetic mirroring comparable to this missing component. We discuss other possible electric field formation mechanisms, such as the deflection of the electric field due to the ExB rotation of electrons in the diverging magnetic field [3]. [1] K. Matyash, R. Schneider, S. Mazouffre, S. Tsikata, and L. Grimaud, Plasma Sources Sci. Technol. 28, 044002 (2019).; [2] J. Simmonds and Y. Raitses, Journal of Applied Physics (2021); [3] N. Fisch, Y. Raitses, and A. Fruchtman, Plasma Physics and Controlled Fusion 53, 124038 (2011). |
Tuesday, November 9, 2021 3:00PM - 3:12PM Not Participating |
JO08.00006: Speed-Limited Particle-in-Cell Simulations of Hall Thrusters in 3D Joseph Theis, Gregory R Werner, Thomas G Jenkins, John R Cary The speed-limited particle-in-cell (SLPIC) algorithm is being investigated as a means for fully-kinetic 3D simulations of Hall thrusters (HTs). Fully-kinetic 3D simulations of HTs are needed because electron cross field transport, which decreases device efficiency, is primarily driven by the kinetic, electron drift instability. Traditional PIC is computationally slow because of the short Debye length and large plasma frequency in HTs. SLPIC, a time-domain algorithm that limits the speed of the fastest electrons, has the potential to speed up simulations by decreasing the plasma frequency and only resolving relevant phenomena like the electron cyclotron frequency. We have shown that SLPIC can simulate electric discharge, collisions, and wall interactions, which are relevant to HTs. We plan to benchmark SLPIC against other PIC codes and explore oscillations in HTs and their effect on electron cross field transport. |
Tuesday, November 9, 2021 3:12PM - 3:24PM |
JO08.00007: Investigation of atmospheric pressure plasma jet propagation on a dielectric surface using different shield gases Mehrnoush Narimisa, Yuliia Onyshchenko, Olivier Van Rooij, Ana Sobota, Rino Morent, Nathalie De Geyter Improving [MN1] the atmospheric pressure plasma jet (APPJ) performance has always been an essential issue, which may be solved by altering plasma proces parameters, modifying jet configuration, controlling ambient conditions, and other approaches. This study investigates the significance of argon and nitrogen shield gases on the propagation behavior of an argon APPJ upon a quartz dielectric surface using various diagnostics methods by varying capillary-sample distance, shield gas type and flow rate. Comsol gas flow dynamic simulations and Schlieren imaging indicate that the argon distribution pattern differs when using argon or nitrogen shield gas. Furthermore, the I-V waveforms of the discharge suggest that an increase in argon shield gas flow rate results in a discharge power deviation. Optical emission spectroscopy (OES) shows that using nitrogen shield gas only influences N2 reactive species, while using argon enhances the intensity of all detected reactive species, especially in the remote distances from the plasma jet. These findings were in agreement with the fast intensified charge-couple device (ICCD) results, where it was observed that the size of the plasma propagation pattern and plasma branches are larger when increasing the argon shield gas flow rate. The outcomes of this study show that the employment of a shield gas could improve the plasma efficiency to achieve the desired plasma spreading on a treated surface. [MN1]1300 characters |
Tuesday, November 9, 2021 3:24PM - 3:36PM |
JO08.00008: 1D diagnostics of neutral particles in low temperature plasmas with single shot coherent Rayleigh-Brillouin scattering Alexandros Gerakis, Robert Randolph Single shot coherent Rayleigh-Brillouin scattering (CRBS), a non-linear, four-wave mixing laser diagnostic technique, is applied for the measurement of the translational temperature and density of neutral species in a low pressure xenon DC glow discharge. The single shot CRBS configuration scans the entire velocity distribution function of the neutral species in the medium within the duration of a single laser shot (approximately 150 ns). CRBS spectra of neutral species are obtained at different points radially across the xenon glow discharge, mapping horizontal temperature and density profiles, simultaneously. Experimentally obtained spectral lineshapes show good agreement when compared to simulated ones.The CRBS measurements within a glow discharge presented here can lead to diagnostics of neutral species in similar environments such as arc discharges, flames, plasma torches, etc. Additionally, we discuss the progress toward the implementation of a novel 1D single shot CRBS scheme, which will allow for the simultaneous, single shot measurement of quantities of interest across line profiles of extended dimensions in a variety of low temperature plasmas. |
Tuesday, November 9, 2021 3:36PM - 3:48PM |
JO08.00009: Volumetric Electric Charge Dissipation after Streamer Corona by EFISH and Probe Measurements Skye Elliott, Arthur Dogariu, Thomas B Coates, Sergey Leonov The aim of this work is to study the dynamics of volumetric electric charge deposited by a single pin electrode streamer corona in atmospheric air. Recent studies show that the electric charge remaining on a dielectric surface or in space after the first pulse significantly affects electric field distribution and morphology of followed discharges [JPhD 48 465201; PSST 25-6 20168]. In this study, two methods were employed to measure the electric potential redistribution during and after dissipation of the pulsed 100kV streamer corona: electrostatic probes and the EFISH method (Electrical Field Induced Second Harmonic). It was found that the volumetric charge of a positive pulse polarity occupies a zone up to 100mm from the pin electrode. The followed applied voltage of a negative polarity leads to a partial neutralization of the previous charge and to a generation a layer with high-amplitude electric field. This layer prevents the propagation of the streamers at the next positive polarity pulse. In the case of negative first pulse, the discharge develops differently by way of reducing the streamers length in the first phase of propagation. Application of two independent methods allowed inside the details of steamer discharge dynamics at alternating polarity waveform. |
Tuesday, November 9, 2021 3:48PM - 4:00PM |
JO08.00010: Single-Shot Hyperspectral Imaging of Weakly Ionized Plasma and Chemiluminescence Emissions Zichen He, Zhili Zhang A compressed sensing based single-shot hyperspectral imaging system composed of a PI 2300i spectrometer, a PI-MAX4 ICCD camera, a Texas Instruments Light Crafter 4500 Digital Micromirror Device (DMD) and collection optics has been implemented on hyperspectral imaging of emissions from glow discharge and flame. The raw three-dimensional (3D) hyperspectrum from the emissions, consisting of two-dimensional spatial and one-dimensional spectral information, was first encoded by a random binary pattern from the DMD, and then compressed by the spectrometer into a coded 2D spectral image. The hyperspectrum then can be computationally reconstructed from the coded 2D spectral image with the coding pattern, restoring intensity at each voxel of the 3D hyperspectrum. Hyperspectra of the emissions of weakly ionized air and a methane-air flame were measured, the results agree to conventional spectroscopic measurements. The compressed single-shot hyperspectral imaging technique will provide highly efficient high-speed spectroscopic measurements on plasmas and other reactive systems. |
Tuesday, November 9, 2021 4:00PM - 4:12PM |
JO08.00011: Coupling a X-Pinch X-ray generator with a gas gun launcher to perform a crystallographic analysis of shocked materials under shock loading towards X-ray diffraction Camille Chauvin, David Palma de Barros The comprehension of materials mechanical behavior under dynamic loading needs to be detailed particularly when a phase change occurs to improve actual numerical models. Macroscopic velocity measurements usually implemented in dynamic experiments are not sufficient to fully understand the transition kinetics. X-ray diffraction is a complementary technique well suited to investigate the shocked materials crystal structure. CEA Gramat has set up a X-Pinch X-ray source adapted to carry out X-ray diffraction on the nanosecond scale. An experiment was set up to perform X-ray diffraction on reflection geometry of both static and shocked samples. A synchronization system was especially designed to couple the source and a single stage gas gun. The beam emission of this X-Pinch source is triggered directly into the impacted target and delayed long enough to let the shock waves reach the sample under investigation. Diffraction patterns are collected onto imaging plates before and during the experiment. Standard velocimetry is also used to retrieve the material state evolution and verify the synchronization with the beam emission. Several experiment were carried out to investigate tin solid-solid phase transition between beta and gamma phases. Shots at pressures beneath and above the transition were performed to observe the crystallographic evolution of tin single crystals. X-ray emission hardly ever spread over 100 ns and synchronization was quite satisfying in most of cases. The collected diffraction patterns showed promising results to propose the first hypothesis of tin behavior under shock loading thanks to this X-Pinch source. Similar experiments carried out on synchrotron showed similar trends, which is encouraging to continue such experiments. |
Tuesday, November 9, 2021 4:12PM - 4:24PM |
JO08.00012: Langmuir Probe Measurements in HIDRA Sam Smith, Andrew J Shone, university E illinois The Hybrid Illinois Device for Research and Applications (HIDRA) is a toroidal plasma device at the University of Illinois Urbana-Champaign (UIUC). HIDRA's main task is to do plasma material interaction (PMI) studies with different materials including liquid lithium. Currently plasma parameters are measured using a He plasma and He spectrum with a collisional radiative model (CRM) with ne = 2×1018 m-3 and Te = 10-20 eV. When HIDRA operated as WEGA in Greifswald, the device was able to reach electron temperatures up to Te = 20eV and densities ne ~1x1018 m-3. The spectroscopic method does not give radial profiles of the plasma hence Langmuir probe measurements need to be performed to verify and benchmark the spectroscopy and CRM. These measurements are vital to understand results that are seen in experiments with lithium in particular. The HIDRA plasma is heated via ECRH with up to 26 kW of heating power, using two 2.45 GHz magnetrons. In the Fall of 2021, measurements of the plasma parameters will be performed using Langmuir probes. There are two edge Langmuir probes (ELPs) found at the outer radius of HIDRA that will be used to measure the plasma characteristics at the edge, and how they change throughout the course of the plasma. A pneumatically driven reciprocating diagnostic arm can send a Langmuir probe into and out of the plasma in approximately 200 ms. The reciprocating Langmuir probe (RLP) will give measurements of the plasma parameters radially across the plasma. Measurements with the RLP and ELPs will also be done with lithium exposure, to see how lithium effects the electron temperature and density of the plasmas and compare this to the Te and ne measured with the CRM . This presentation will give the results of how magnetron power effects the plasma of HIDRA, including profiles for the edge plasma and throughout the plasma, and how they change with the introduction of lithium. |
Tuesday, November 9, 2021 4:24PM - 4:36PM |
JO08.00013: Supersonic Hybrid Non-equilibrium Plasma Reactor for Co-Production of Hydrogen and Value-Added Solid Carbons from Methane Andrey Starikovskiy, Yiguang Ju The increasing concern of climate change requires immediate action to reduce CO2 emissions from directly burning fossil fuels. At the same time, the recent increase of renewable electricity and the need of large scale electricity storage provide a great opportunity to produce hydrogen and valuable carbon from natural gas by taking advantage of its abundant resource. The predominant commercial method for production of hydrogen and carbon from natural gas is the high temperature thermal cracking process. However, the thermal cracking method has low yield and produces less valuable carbon but large amounts of polluting emissions. The objective of this work is to develop and optimize an innovative supersonic hybrid non-equilibrium plasma reactor for efficient and tunable co-production of hydrogen and value-added solid carbons with negative CO2 footprint. The reactor for controlled methane reforming and H2/carbon synthesis is designed and assembled. Plasma modeling shows that a pulsed gliding arc can reach to 4000 K for transient chemical reforming. Supersonic nozzle provides rapid reaction quenching to enable non-equilibrium chemical synthesis to achieve higher yield and selectivity. |
Tuesday, November 9, 2021 4:36PM - 4:48PM |
JO08.00014: Production of Energetic Nanodiamond via Atmospheric Plasma Surface Treatment Chi-Chin Wu, Jennifer L Gottfried, Dinesh Thapa, Rose A Pesce-Rodriguez, Scott D Walck This work describes a new approach conducted at US Army Combat Capabilities Development Command Army Research Laboratory (ARL) for producing energetic nanodiamond via atmospheric helium plasma surface treatment of commercial detonation nanodiamond (DND) in dielectric barrier discharge (DBD) plasma reactors. An originally “bad” DND previously determined to have high levels of graphitic carbons and contaminants transformed into a “good” DND with stable diamond characteristics as good as best-available commercial DND. Post-plasma-treatment, the “bad” DND was found to have reduced d-spacing for each diamond diffraction plane [(111), (220), (311)], identical to a high quality DND – with significantly reduced numbers of graphitic shells, leading to increased energy release at the microsecond timescale via the laser-induced air shock for energetic materials (LASEM) technique. Transmission electron micrographs also revealed more distinct diamond core, indicating successful removal of impurities by plasmas. This paper provides a new alternative for producing energetic DND while simultaneously underscoring the importance of recognizing not only the benefits, but also the challenges of applying plasma techniques to novel material production. |
Tuesday, November 9, 2021 4:48PM - 5:00PM |
JO08.00015: Porting the PUMImbbl library to GPUs and integration in the hPIC2 Particle-in-Cell code Md Fazlul Huq, Vignesh Vittal-Srinivasaragavan, Logan Meredith, Onkar Sahni, Davide Curreli GPU-capable PUMImbbl library, which provides multi-block boundary layer (MBBL) mesh capability under the Parallel Unstructured Mesh Infrastructure (PUMI), is integrated with the hPIC2 code. PUMImbbl library employs an implicit representation of the multi-block mesh and exploits tensor product mesh structure in multiple dimensions. In addition, PUMImbbl library supports complex geometry such as tile gaps by making certain blocks inactive in the mesh as desired by the application. The implicit representation of such a mesh is based on parameters that describe every block in each direction (including blocks with geometrically graded/boundary layer elements). The PUMImbbl allows us to incorporate a GPU-capable non-uniform mesh into the hPIC2 Particle-in-Cell code. hPIC2 is a full-orbit, hybrid Particle-in-Cell (PIC) code targeting Plasma-Surface Interaction problems. hPIC2 is developed using the C++ library of Kokkos performance portability framework for hybrid CPU/GPU parallelism. Thanks to the new mesh, hPIC2 can simulate 2D plasma problems on non-uniform meshes using GPUs, and solve problems on large plasma domains including the steep gradients normally encountered in plasma sheaths, with a relatively small number of cells, effectively reducing the total number of particles needed for the simulation and the overall computational cost. |
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