Bulletin of the American Physical Society
64th Annual Meeting of the APS Division of Plasma Physics
Volume 67, Number 15
Monday–Friday, October 17–21, 2022; Spokane, Washington
Session CO07: Fundamental Plasmas: Analytical and Computational TechniquesLive Streamed
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Chair: Paulo Alves, UCLA Room: 401 ABC |
Monday, October 17, 2022 2:00PM - 2:12PM |
CO07.00001: Simulating conservative and dissipative waves using quantum signal processing algorithms Ivan Novikau, Ilya Y Dodin, Edward A Startsev Quantum Signal Processing (QSP) and Quantum Singular Value Transformation (QSVT) methods are the state-of-the-art quantum algorithms for Hamiltonian and matrix inversion computation. |
Monday, October 17, 2022 2:12PM - 2:24PM |
CO07.00002: A quantum-inspired method for solving the Vlasov-Poisson equations Erika Ye, Nuno F Loureiro Kinetic simulations of collisionless (or weakly collisional) plasmas using the Vlasov equation are often infeasible due to high resolution requirements and the exponential scaling of computational cost with respect to dimension. Recently, it has been proposed that matrix product state (MPS) methods, a quantum-inspired but classical algorithm, can be used to solve partial differential equations with exponential speed-up, provided that the solution can be compressed and efficiently represented as an MPS within some tolerable error threshold. In previous work, we found that when solving the Vlasov-Poisson equations in 1D1V, important features of linear and nonlinear dynamics, such as damping or growth rates and saturation amplitudes, can be captured while compressing the solution significantly. Here, we investigate the practicality of using MPS methods for simulating (nonlinear) Landau damping in up to 3D3V and the speed-up the algorithm is able to provide. |
Monday, October 17, 2022 2:24PM - 2:36PM |
CO07.00003: Vlasov Simulation of Relativistic Plasmas in 2D+2P Jeff W Banks, Jennifer K Gorman, Richard L Berger, Thomas D Chapman The increasing power and energy of multi-MegaJoule laser facilities are projected to yield electron temperature up to 10 keV. In this regime, when plasma densities approach quarter-critical, the phase velocity of plasma waves associated with Two Plasmon Decay and SRS backscatter will be close to the speed of light. Such waves would be strongly damped according to the non-relativistic dispersion relation, but not with the relativistic one. Here, the effect of relativity on stimulated Raman scattering is simulated with our new 2D+2P continuum LOKI code capable of simulating relativistic plasmas. The discretizations use sixth-order accurate conservative finite differences to reduce computational cost, and employ MPI parallelism to efficiently use large computational resources. Code performance is assessed for collisionless damping of Langmuir waves, and results are discussed in the context of theoretical prediction. |
Monday, October 17, 2022 2:36PM - 2:48PM |
CO07.00004: Formulating two-fluid dissipative magnetohydrodynamics for general-relativistic plasmas Elias R Most, Jorge Noronha, Alexander A Philippov Relativistic plasmas are central to the study of black hole accretion, jet physics, neutron star mergers, and compact object magnetospheres. I will describe a fully relativistic covariant 14-moment based two-fluid system appropriate for the study of electron-ion or electron-positron plasmas, which is obtained from the relativistic Boltzmann-Vlasov equation. Crucially, this new formulation can account for non-ideal effects, such as anisotropic pressures and heat fluxes. Finally, I will show how relativistic two-fluid plasmas can be recast into a dissipative single fluid formulation with dissipative corrections, while still maintaining self-consistent evolution equations for electron temperature and momentum. |
Monday, October 17, 2022 2:48PM - 3:00PM |
CO07.00005: A computationally validated quasilinear model for characterizing anomalous transport in current-carrying magnetized plasmas G. V. Vogman, J. H. Hammer Collisionless low-beta plasmas in pulsed power inertial confinement fusion experiments are strongly influenced by nonlinear kinetic physics, which is difficult to characterize and which leads to anomalous transport. To understand how microphysics governs macroscopic transport properties, a self-consistent closed-form quasilinear (QL) theory analysis is developed and validated using state-of-the-art fourth-order accurate continuum kinetic simulations. The QL model describes a fully-kinetic two-species current-carrying magnetized plasma while fully encapsulating ion and electron gyromotion. The QL system of equations are solved numerically and self-consistently, without invoking commonly-used asymptotic and/or Maxwellian approximations. The QL model is validated against nonlinear noise-free Vlasov-Poisson simulations of a two-species low-beta plasma undergoing the lower hybrid drift instability. The QL predictions are shown to be consistent with multiple aspects of the simulations. The theoretical and computational study demonstrates progress toward a validated description of the nonlinear state of current-carrying plasmas and provides bounds on the degree to which QL theory can predict anomalous properties. |
Monday, October 17, 2022 3:00PM - 3:12PM |
CO07.00006: Machine-learned boundary conditions for the optimal absorption of charged particles in particle-in-cell simulations Mark Almanza, Amadou Diallo, Edoardo Zoni, Remi Lehe, E. Paulo Alves When running numerical simulations of open systems, solvers in the simulation domain must be complemented by appropriate absorbing boundary conditions (BCs) to minimize the impact of a finite box size. In Particle-in-Cell simulations, Perfectly Matched Layers (PMLs) are a standard method for absorbing electromagnetic radiation that would escape the domain. However, developing analogous BCs for the absorption of charged particles remains a long-standing problem. |
Monday, October 17, 2022 3:12PM - 3:24PM |
CO07.00007: Characterization of uncertainties in electron-argon collision cross sections under statistical principles Seung Whan Chung, Todd A Oliver, Laxminarayan L Raja, Robert D Moser Prediction for argon plasma is predicated upon the accurate characterization of electron-impact collision cross-sections, which determine the key reaction rates and transport properties of the plasma. Although these cross-sections have been the subject of experiments over decades, the resulting measurements do not always agree, and the uncertainties in the cross-sections have not been characterized. We evaluate the uncertainties in electron-argon collision cross-sections using Bayesian approach. Six collision processes (elastic momentum transfer, ionization, and 4 excitations) are characterized with semi-empirical models, whose parametric uncertainties effectively capture the essential features for the plasma chemistry/transport. These semi-empirical model are augmented by a Gaussian-process-based model to represent both systematic error in the experiments as well as the inadequacy of the semi-empirical forms. The parameters of the resulting model are calibrated via Bayesian inference using data from electron-beam experiments and ab-initio simulations. The resulting uncertainty in the cross-section model captures the scattering among the measurements, and is further validated against the swarm-parameter experiments via a 0D-Boltzmann analysis. |
Monday, October 17, 2022 3:24PM - 3:36PM |
CO07.00008: Analysis of the Shock-Induced Current Due to a Charged Particle Impacting a Conducting Surface Dion Li, Patrick Wong, David Chernin, Yue Ying Lau This paper compares the transient induced current due to the electromagnetic shock produced by a charged particle impacting a perfectly conducting plate [1], with the classical, quasi-static induced current of Ramo and Shockley (RS) [2]. We consider the simple model of a line charge, removed upon striking the plate. We find that the induced current due to the shock is negligible compared with the RS current for nonrelativistic impact energies, but is more significant as the impact energy becomes mildly relativistic. The implications of these findings on multipactor discharge and on high power microwave sources are discussed. |
Monday, October 17, 2022 3:36PM - 3:48PM |
CO07.00009: Investigating Mechanisms of State (De)Localization in Highly-Ionized Dense Plasmas Thomas D Gawne, Patrick J Hollebon, Gabriel Pérez-Callejo, Oliver S Humphries, Justin Wark, Sam M Vinko Predictions from standard ionisation potential depression (IPD) models have come under scrutiny in light of significant discrepancies with continuum lowering measurements at recent experiments involving highly-ionised dense plasmas. We attribute these discrepancies, in part, to difficulties in defining valence states as purely bound or purely free in plasmas with Debye lengths comparable to the inter-particle spacing. Here, we describe an approach to resolve this difficulty using finite-temperature density functional theory (FT-DFT). The "boundness" of a valence states is quantified by the spatial localization of its Kohn-Sham wavefunction, in a quantity we have termed ‘dimensionality’. When applied to ground state calculations of a simple metal and an ionic compound, the dimensionality correctly identifies localized and delocalized states. We apply the dimensionality to investigate the localization mechanism of isochoric heating in Al, Mg, and MgF2. IPD levels are then extracted from the DFT calculations and compared with standard models and previous experiments. |
Monday, October 17, 2022 3:48PM - 4:00PM |
CO07.00010: Ab initio path integral Monte Carlo simulations of hydrogen snapshots at warm dense matter conditions Maximilian P Boehme, Zhandos A Moldabekov, Jan Vorberger, Tobias Dornheim We combine ab initio path integral Monte Carlo (PIMC) simulations with fixed ionic configurations, obtained by DFT-MD simulations, in order to solve the electronic problem for hydrogen under warm dense matter conditions. To solve the divergence problem in the Ewald-sum for attractive potentials we employ the pair-approximation. This approach is compared against the much simpler Kelbg pair-potential. We find very favorable convergence behavior towards the former. Since PIMC does not require any further assumptions regarding exchange and correlations of the many-body system, we then compare electronic densities obtained from our snapshot PIMC calculations with DFT calculations in the metallic regime. Furthermore, we investigate the manifestation of the resulting fermionic sign problem in our snapshot PIMC simulations. This gives us the unique capability to study the properties of warm dense hydrogen from ab initio simulations without any further assumptions, like the functional form of the exchange-correlation effects or fixed fermionic nodes. Thus, snapshot PIMC enables us to obtain the exact density response of warm dense hydrogen. This is extremely valuable to both experiments, like X-Ray Thomson scattering, as well as the development of new XC-functionals. |
Monday, October 17, 2022 4:00PM - 4:12PM |
CO07.00011: Using Microgravity Dusty Plasma to Study Connections Between Non-Equilibrium Tsallis Statistics, Nonlinear Fokker Planck and Fractional Laplacian Bradley Andrew, Evdokiya Kostadinova, Lorin S Matthews, Truell W Hyde, Emerson Gehr, Joshua Padgett |
Monday, October 17, 2022 4:12PM - 4:24PM Author not Attending |
CO07.00012: Three-dimensional N-body charged particle simulation employing analytical Kepler solutions in the presence of background magnetic field. Yasutaro Nishimura Charged particle diffusion in the presence of magnetic field is studied numerically by a N-body simulation. Central forces (Coulomb forces) between charged particles are computated directly without employing field quantities. When the distance between the two charged particles become comparable to the Landau length (where the kinetic and potential energy becomes comparable), numerical solutions are replaced by analytical Kepler solutions (by regarding the problem as a binary collision problem). The computational method with the analytical solutions are applied in three dimensional computation (by finding out the two-dimensional planes). The electron diffusion coefficient is computed in boundary-less opened domains whose scaling lies between the the classical estimation D_e ~ T_e/ B^2 and the Bohm diffusion D_e ~ T_e/ B, depending on the ratio between the Larmor radius and the Landau length. |
Monday, October 17, 2022 4:24PM - 4:36PM |
CO07.00013: Transmission Loss of a millimeter wave pulse through a dielectric window Ruei-Fu Jao, Kaviya Aranganadin, Hua-Yi Hsu, John P Verboncoeur, Ming-Chieh Lin Millimeter waves have become increasingly important in wireless communication today. It is well known that a dielectric window exhibits almost perfect transmission for the center frequency of millimeter waves. However, this might not be true for a pulsed wave. In this work, we study the transmission loss of a millimeter wave pulse centered at 35 GHz traveling through a dielectric window. The transmission function of a continuous wave within the bandwidth from 0 to 100 GHz has been obtained using the transfer matrix method. The millimeter wave of 35 GHz pulsed from 100 ps to 1 us in time domain has been Fourier transformed to the frequency domain so that the transmittance of the pulsed wave in the frequency domain can be calculated. The transmission loss has been analyzed for various pulse durations. After inverse Fourier transform of the transmittance in the frequency domain back to the time domain, one can compare the result with the incident pulse to see the pulse distortion and transmission loss. Numerical simulations using finite element and finite difference time domain methods have been performed to verify the calculated results by the transfer matrix method combined with Fourier transform. Detailed methodology and analysis of the study will be presented. |
Monday, October 17, 2022 4:36PM - 4:48PM |
CO07.00014: Strong Coulomb Coupling Influences Ion and Neutral Temperatures in Atmospheric Pressure Plasmas Marco D Acciarri, Scott D Baalrud, Christopher H Moore Cold atmospheric pressure plasmas (CAPP) have been widely tested for numerous applications showing promising results and an increasing interest due to the low running cost and operational simplicity. However, there is a lack of understanding about the main mechanisms involved in the plasma dynamics. In this work, we show that the ion species are often strongly coupled in CAPP and this leads to physical effects that currently are not accounted for in standard simulation techniques. Using first-principles Molecular Dynamics simulations, we observed that the ion and neutral temperatures are influenced by Disorder Induced Heating (DIH), ion-neutral temperature relaxation through collisions and ion-neutral 3-body recombination. The observed effects show that CAPP are sufficiently dense that they are influenced by strong correlation effects associated with many-body interactions that are not treated in the dilute limit. |
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