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 JM10: Mini-Conference: Charged Particle Transport in High-Energy-Density Plasma IILive Streamed
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Chair: Patrick Knapp, SNL; Lucas Stanek, MSU Room: 206 CD |
Tuesday, October 18, 2022 2:00PM - 2:12PM |
JM10.00001: Mean Force Kinetic Theory Calculations of Transport in High Energy Density Plasmas Scott D Baalrud Mean force kinetic theory is an approach to extend plasma kinetic theory into the strongly coupled regime. It is based on a new closure of the BBGKY hierarchy that expands about the deviations of correlations from their equilibrium values, rather than the strength of correlations. The model has been tested by computing transport coefficients for the hydrodynamic evolution of plasmas and comparing with molecular dynamics simulations and experimental results. The general finding is that the approach extends plasma theory to Coulomb coupling parameters less than 10. This talk will summarize recent results in applying the method to high energy density plasmas, including extensions of the classical physics-based model to also include partial degeneracy of electrons that is common in the warm dense matter regime. This is accomplished from an approach based on the Uehling-Uhlenbeck equation and a quantum generalization of the potential of mean force. Results will be shown for both ionic transport process such as diffusion and shear viscosity, as well as electron-ion scattering processes, such as electrical conductivity, thermal conductivity and stopping power. |
Tuesday, October 18, 2022 2:12PM - 2:24PM |
JM10.00002: Yukawa Friedel-tail pair potentials for warm dense matter applications Lucas J Stanek, Chandre Dharma-wardana, Michael S Murillo Accurate equations of state (EOS) and plasma transport properties are essential for numerical simulations of warm dense matter, encountered in many high-energy-density experiments. Molecular dynamics (MD) is a simulation method that generates EOS and transport data using an externally provided potential to dynamically evolve the particles. To minimize computational cost, pair interaction potentials needed in MD may be obtained from the neutral-pseudoatom (NPA) approach, a form of single-ion density functional theory (DFT) where many-ion correlation effects are included. Standard N-ion DFT-MD also provides pair potentials by force matching but at much greater computational cost. In this talk we present a simple analytic model for pair potentials with physically meaningful parameters based on a Yukawa form with a thermally damped Friedel tail (YFT) applicable to systems containing free electrons. The YFT model accurately fits NPA pair potentials or the non-parametric potentials from N-ion DFT-MD force matching, showing excellent agreement for a wide range of conditions and recovers structural data like structure factors and pair-distribution functions; we discuss the applicability of the YFT model to ionic transport coefficients. |
Tuesday, October 18, 2022 2:24PM - 2:36PM |
JM10.00003: Cyclic Conversion of Particle Kinetic Energy into Reconnected Magnetic Field Energy Bruno Coppi Magnetic reconnection has been considered almost exclusively as a process through which magnetic energy is converted into particle kinetic energy. On the other hand recent theoretical developments [1] have illuminated the fact that a cyclic exchange of kinetic and magnetic energy can take place in weakly collisional plasmas by a reconnection process that is allowed by the relevant finite thermal conductivities (longitudinal and transverse to the unreconnected magnetic field). The combined effects of the aligned electron temperature and density gradients allows the reconnected field to grow involving layers that, differently from the case of conventional reconnection driven by current density gradients and relying on an Ohm’s law, remain significant even when the scale distances of the unreconnected field are large. The considered reconnection process is inherently cyclical and, comparing it to the Biermann battery driven by misaligned electron temperature gradient, can be viewed as an alternator. In retrospect, the well known sawtooth and fishbone oscillations of well confined plasmas belong to the class of processes identified on the basis of the results of Ref. [1] considering that the driving factor of the involved reconnection is the particle thermal energy gradient in the first case and the combination of this factor and mode-particle resonances with an injected high energy population in the second case. |
Tuesday, October 18, 2022 2:36PM - 2:48PM |
JM10.00004: Feasibility of measuring ionic diffusion in x-ray heated foils using x-ray radiography on Z Patrick F Knapp, Kyle R Cochrane, Nichelle L Bennett, Lucas J Stanek, Kristian Beckwith Ionic diffusion is the process by which ions of different species traverse an initial interface. In moderate to strongly coupled plasmas this process can be stronger than expected by classical arguments, leading to more efficient mixing. We present measurements of this process taken using a novel platform on Z where a bright x-ray source is used to heat a sample comprised of repeating low-Z/high-Z interfaces. X-ray radiography is used to measure the change in the spread of the edge created by the interface as a function of time. Our results show that it should be possible to measure this phenomenon with existing capabilities and provide constraining data, though better characterization of the drive and sample conditions are needed for quantitative comparisons. |
Tuesday, October 18, 2022 2:48PM - 3:00PM |
JM10.00005: New ab initio methods for electron and Ion transport properties of matter extreme conditions: from electronic stopping power to ion diffusion. Alexander J White Calculation of transport coefficients from time-dependent atomistic methods can require one to two orders of magnitude simulation times than static properties. In extreme conditions the increased costs of electronic structure can often be prohibitive. However, the direct calculation of transport is highly desirable for verification of in-line models or the building of accurate datasets in theoretically challenging regimes. We can alleviate some of this computational expense, without resorting to lower-level theory, through the use of mixed stochastic-deterministic methods. We will highlight the applications of this method to both ion transport in the Born-Oppenheimer (diffusion) and Non-Born-Oppenheimer (ion stopping) regimes. |
Tuesday, October 18, 2022 3:00PM - 3:12PM |
JM10.00006: Break
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Tuesday, October 18, 2022 3:12PM - 3:24PM |
JM10.00007: Investigation of Nonlocal Electron Transport in High-Energy-Density Plasmas Using Ab Initio Methods Katarina A Nichols, Alexander J White, Lee A Collins, Suxing Hu Nonlocal electron transport is key to determining laser-target coupling for direct-drive inertial confinement fusion (ICF). We have utilized a combination of the mixed Kohn–Sham (mKS)[1,2] and orbital-free (OF)[3] approaches to time-dependent density functional theory (TD-DFT) and various analytical methods to calculate the nonlocal electron mean free path (MFP) in warm/hot dense CH “conduction-zone” plasmas relevant to ICF conditions. We will use the results from these TD-mKS-DFT and TD-OF-DFT calculations to develop an analytical model for the electron MFP and then apply this model to radiation-hydrodynamic simulations of ICF implosions. In this way, we hope to close the gap between theory and experiment for laser–target coupling that is currently evidenced by soft x-ray self-emission measurements. The expected results will improve the predictive capability for laser–target coupling, hot-spot formation, and burn-wave propagation in ICF simulations. [1] A. J. White et al., Phys. Rev. Lett. 125, 055002 (2020).
[2] A. J. White et al., J. Phys.: Condens. Matter 34, 174001 (2022).
[3] Y. H. Ding et al., Phys. Rev. Lett. 121, 145001 (2018).
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Tuesday, October 18, 2022 3:24PM - 3:36PM |
JM10.00008: The influence of trajectories and pseudization on first-principles calculations of electronic stopping in warm dense matter Alina Kononov, Alexandra Olmstead, Thomas Hentschel, Stephanie B Hansen, Andrew D Baczewski Scarce experimental data for ion transport in warm dense matter makes first-principles results valuable benchmarks for simpler models. However, high computational costs typically limit first-principles studies to temperatures below ~10 eV and make it difficult to characterize sensitivities to various approximations. We use time-dependent density functional theory to compute electronic stopping powers of protons in warm dense deuterium, carbon, and aluminum at densities up to 10 g/cc and temperatures up to 20 eV. We define a metric to quantify sampling errors caused by finite proton trajectories and find that comparably faithful trajectories lead to average stopping powers that do not depend on ion temperature for materials out of thermal equilibrium. On the other hand, we see a strong dependence on electronic temperature in some cases: heating solid-density aluminum from 1 eV to 20 eV reduces the Bragg peak by ~30% and shifts it toward ~50% higher velocities. Comparing results computed with different pseudization schemes reveals competing effects within the contributions of bound and free electrons. This work guides improvements to much more efficient stopping models based on average atom methods. |
Tuesday, October 18, 2022 3:36PM - 3:48PM |
JM10.00009: Prospects for calculating plasma transport properties on quantum computers Andrew D Baczewski, Alina Kononov, Lucas Kocia, Shivesh Pathak, Antonio E Russo, Stefan Seritan Quantum computers might eventually be used to simulate quantum systems more accurately than classical computers. But it isn't yet clear how large or reliable such a machine would need to be to be scientifically useful for many applications in plasma physics. We begin to address these questions for calculations of transport properties like stopping power and conductivity in the degenerate limit, as these transport calculations are among the most computationally expensive on classical computers and the attendant errors are difficult to quantify in the absence of experiments. We will describe quantum algorithms for implementing these calculations and provide estimates for the size and error rates of quantum computers that would outperform classical computers at scientifically useful calculations. We will also discuss implications for the ultimate limits of accuracy in calculating these properties on classical computers. |
Tuesday, October 18, 2022 3:48PM - 4:18PM |
JM10.00010: Review of the first charged-particle transport coefficient comparison workshop Paul E Grabowski, Stephanie B Hansen, Michael S Murillo, Liam G Stanton, Frank R Graziani, Alex B Zylstra, Scott D Baalrud, Philippe Arnault, Andrew D Baczewski, Lorin X Benedict, Christophe Blancard, Ondrej Certik, Jean Clerouin, Lee A Collins, Sean Copeland, Alfredo A Correa, Jaiyu Dai, Jerome Daligault, Michael P Desjarlais, Chandre Dharma-wardana, Gerald Faussurier, Jeff R Haack, Tomorr Haxhimali, Anna C Hayes-Sterbenz, Yong Hou, Suxing Hu, Daniel S Jensen, Gerard Jungman, Grigory Kagan, Dong Kang, Joel D Kress, Qian Ma, Mathieu Marciante, Edmund R Meyer, Robert E Rudd, Didier Saumon, Luke Shulenburger, Robert L Singleton, Travis Sjostrom, Lucas J Stanek, Charles Starrett, Christopher C Ticknor, Sonata Valaitis, Joel A Venzke, Alexander J White
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Tuesday, October 18, 2022 4:18PM - 5:00PM |
JM10.00011: Discussion
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