Bulletin of the American Physical Society
60th Annual Meeting of the APS Division of Plasma Physics
Volume 63, Number 11
Monday–Friday, November 5–9, 2018; Portland, Oregon
Session TM9: Mini-conference on the Crossover between High Energy Density Plasmas and Ultracold Neutral Plasmas: I |
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Chair: Liam Stanton, San Jose State University Room: OCC C123 |
Thursday, November 8, 2018 9:30AM - 9:50AM |
TM9.00001: Federal Science Agency Perspectives on Strongly Coupled Plasmas Jason A Marshall, Vyacheslav Lukin The strongly coupled plasma regime presents opportunities for discovery science and appears in many physical situations of direct relevance to national security. These include understanding of high-energy density (HED) astrophysical systems, fusion plasmas, dusty ionospheric plasmas, plasmas from ultra-fast laser-materials interactions, and plasmas generated by conventional explosives. Since the creation of ultracold plasmas in 1999, the atomic, molecular, and optical (AMO) physics and plasma physics communities have enjoyed unprecedented experimental control over the creation and diagnosis of the resulting strongly coupled plasmas. Federal funding agencies have sought to bring together the plasma physics and AMO communities in the creation, diagnosis, and modeling of strongly coupled plasmas. Enhancing the ability to create ever stronger coupled plasmas by sculpting particle distribution functions has been of particular interest, allowing to compare experimental studies with theory and computation to develop better understanding of these novel systems. Support has been focused on enhancing the capability of the AMO community to create and diagnose ultracold plasmas, and on coupling these efforts to the HED physics studies where strongly coupled plasmas are often produced. |
Thursday, November 8, 2018 9:50AM - 10:10AM |
TM9.00002: Disparate Regimes of Non-Ideal Plasmas: Connecting the Physics of Ultracold and Hot, Dense Plasmas Michael S. Murillo
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Thursday, November 8, 2018 10:10AM - 10:30AM |
TM9.00003: Ultracold neutral plasmas as high-energy-density plasma simulators Scott Bergeson After presenting an overview of ultracold neutral plasma (UNP) physics, I will explore situations in which ultracold neutral plasmas can be used to simulate the high-energy-density plasma (HEDP) environment. This will include the micro-physics of ion friction, energy and velocity relaxation, electron-ion thermalization, and the separation of hydrodynamic flow and thermal motion. Even though UNP and HEDP science occurs over vastly different scales in temperature and density, thermodynamic and kinetic properties can be scaled using the dimensionless parameters $\Gamma$, the Coulomb strong-coupling parameter, and $\kappa$, the inverse scaled screening length. In UNPs, the value of $\Gamma$ ranges from 0.1 to about 10. The value of $\kappa$ ranges from 0 to 0.6. The low temperature and density make it possible to measure kinetic effects with high precision. Computer modeling and simulations are similarly straightforward, enabling the extraction of diffusion coefficients, Coulomb logarithms, and collision rates. Future areas of HEDP/UNP overlap will be discussed. |
Thursday, November 8, 2018 10:30AM - 10:50AM |
TM9.00004: Impact of New Transport Coefficients on Modeling NIF Experiments Charles Leland Ellison, Frank R Graziani, Christian R Scullard, H. D. Whitley The extreme conditions created at the National Ignition Facility (NIF) probe the warm dense matter regime where quantum degeneracy and strongly coupled plasma effects can become important. When numerically modeling such experiments, it becomes a challenge to accurately model the wide range of parameters exhibited by the imploding plasmas. In this presentation, the adoption of new plasma transport coefficients in the Ares multiphysics code will be discussed. In particular, a new quantum Lenard-Balescu electron-ion coupling model [Scullard Phys. Rev. E 97, 013205 (2018)] and a hybrid plasma viscosity model [Stanton Phys. Rev. E 93, 043203 (2016); Murillo High Energ. Dens. Phys. 4, 49 (2008)] have recently been implemented. The impact of these models will be discussed in the context of a polar-direct-drive exploding pusher platform and more conventional indirect-drive platforms. The importance of the new models will be quantified both in terms of the relative change of the transport coefficients themselves and in differences incurred in the simulated target performance, such as yield. |
Thursday, November 8, 2018 10:50AM - 11:10AM |
TM9.00005: Cold, laser-excited plasmas in strong magnetic fields Georg Raithel, Eric G Paradis, David Anderson Cold, laser-excited plasmas in strong magnetic fields exhibit lower electron heating and three-body recombination rates than field-free plasmas. This raises the prospect of achieving stronger Coulomb coupling of the electron gas. The presented research is aimed at time- and spatially-resolved imaging of such plasmas, and non-invasive electric-field measurement and imaging using Rydberg-level spectroscopy. Results on laser-spectroscopic measurement of plasma electric fields and plasma cyclotron heating will be discussed. We will further report on experimental progress in realizing novel glass-cell Penning plasma trap systems. |
Thursday, November 8, 2018 11:10AM - 11:30AM |
TM9.00006: Electron localization in strong coupling-influenced ultracold plasmas Jacob Roberts, John Guthrie, Puchang Jiang Ultracold plasmas are interesting objects in part because for typical parameters they can exhibit strong coupling influenced behavior and also because they are comparatively straightforward to model using modern computational techniques. Using experimentally-validated molecular dynamics simulations of ultracold plasmas with significant electron strong coupling, we have found that electrons are commonly localized (classically) by ions to finite volumes of space for significant periods of time. This is through the expected Rydberg atom formation, but in addition less tightly bound configurations are common. Up to 10% or more of the electrons are noticeably localized in experimentally accessible ultracold plasma conditions soon after formation. As a result, many collision properties that can be extracted from the molecular dynamics simulations are no longer straightforward to obtain. The relationship between this localization and collision properties will be described, as will the general applicability to plasmas where strong coupling is relevant. |
Thursday, November 8, 2018 11:30AM - 11:50AM |
TM9.00007: Quantum disordered dynamics in the arrested relaxation of a molecular ultracold plasma Edward Grant, Ruoxi Wang, Kevin Madera, Mahyad Aghigh, Fernanda Banic Viana Martins, Kiara Grant, Xixi Qi, John Sous, James Keller Spontaneous avalanche to plasma splits the core of an ellipsoidal Rydberg gas of nitric oxide. Ambipolar expansion first quenches the electron temperature of this core plasma. Then, long-range, resonant charge transfer from ballistic ions to frozen Rydberg molecules in the wings of the ellipsoid quenches the centre-of-mass ion/Rydberg molecule velocity distribution. This sequence of steps gives rise to a remarkable mechanics of self-assembly, in which the kinetic energy of initially formed hot electrons and ions drives an observed separation of plasma volumes. After 300 ns, electron collisional transport processes stop, and the distribution of electron binding energies relaxes to a narrow band just below the ionization threshold. The long lifetime of this system with respect to recombination and neutral dissociation, suggests that this transformation affords a robust state of arrested relaxation, far from thermal equilibrium. We argue that this state of the quenched ultracold plasma offers an experimental platform for studying quantum many-body physics of disordered systems in the long-time and finite energy-density limits. |
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