Bulletin of the American Physical Society
2020 Annual Meeting of the Far West Section
Volume 65, Number 17
Friday–Saturday, October 9–10, 2020; Virtual, Pacific Time
Session D02: Plasma, Fluid, Atomic, Molecular, and Optical PhysicsLive
|
Hide Abstracts |
Chair: Alla Safronova, University of Nevada, Reno |
Friday, October 9, 2020 2:00PM - 2:12PM Live |
D02.00001: Al Double Planar Z-pinch Loads on Various 1 MA Generators Christopher Butcher, Victor Kantsyrev, Alla Safronova, Veronica Shlyaptseva, Ishor Shrestha, Austin Stafford, Adam Steiner, Paul Campbell, Stephanie Miller, Nicholas Jordan, Ryan McBride, Ronald Gilgenbach In previous studies at the UNR high-impedance Marx bank Zebra generator (1.9 $\Omega $, 1.7 MA, 100 ns), Double Planar Wire Arrays (DPWAs) proved to be excellent radiators, and Double Planar Foil Liners (DPFLs) can be also useful for future ICF applications. This presentation will showcase the radiative properties and implosion dynamics of Aluminum (Al) DPWAs and Al DPFLs obtained in joint UNR/UM experiments at the UM low-impedance Linear Transformer Driver (LTD) MAIZE generator (0.1 $\Omega $, 0.6 MA, and 100--250 ns). The DPWAs consisted of two wire planes of micron-scale sized Al wires, while the DPFLs consisted of two planes of micron-scale thickness. Diagnostics in both studies include various filtered x-ray diodes (\textgreater 1.4 keV), spectrometers, and optical shadowgraphy systems; experiments on MAIZE also feature new time resolved load inductance calculations. Applications of this research are discussed. This work was supported by the NNSA under DOE grants DE-NA0003047 and DE-NA0003877. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. [Preview Abstract] |
Friday, October 9, 2020 2:12PM - 2:24PM Live |
D02.00002: Influence of Load Geometry on Nonthermal Emission in High-Energy-Density X-pinch Plasmas on the Zebra Generator Ryan Childers, Alla Safronova, Victor Kantsyrev, Richard Plotkin, Austin Stafford, Dave Ampleford Nonthermal x-rays are used as a fundamental tool to diagnose astrophysical environments, e.g. solar flares and accretion zones of compact objects. Laboratory Z-pinches are efficient producers of nonthermal inner-shell x-rays, which are typically driven by energetic, ``hot'' electrons. In the current study, we explore the production of hot electrons in Z-pinch plasmas through the manifestation of nonthermal inner-shell x-rays. K-shell emission from astrophysically relevant Fe, Ni, and Cr plasmas produced on the 1 MA Zebra generator are studied using stainless steel (Fe: 69{\%}, Ni: 9{\%}, Cr: 20{\%}) X-pinches. X-pinches consist of four wires crossing in the middle that produce fixed hot spots at the cross point. Wire loads are arranged with angle between wires of 31 or 62.5 degrees to investigate the influence of load geometry on x-ray production. Theoretical modeling of hard x-ray (1.6 -- 2.3 {\AA}) K-shell Fe, Ni, and Cr spectra reveals hotter thermal plasma (Te $\ge $ 1 keV) and cooler nonthermal plasma (Te: 10-40 eV), indicating two different plasma regions with presence of hot electron beams. Theoretical modeling used with time-resolved spectral and flux diagnostics shows inner-shell emission intensifies for the 31 degree geometry. [Preview Abstract] |
Friday, October 9, 2020 2:24PM - 2:36PM Live |
D02.00003: Electron-Ion Equilibration in Warm Dense Gold Jacob Molina, Thomas White With the advent of ultrafast MeV electron diffraction, experiments are now able to observe the structural evolution of laser excited systems of gold on a nanometer scale. After excitation, on a picosecond timescale, these systems form a complex non-equilibrium state of matter that cannot be fitted by a linear equilibration model. For example, the importance of bond hardening has been hotly debated. In fact, three separate research groups have observed the structural dynamics of commensurate systems of warm dense gold and come to opposing conclusions, at least partly due to the number of assumptions that must be made to fit the data [1-3]. We have performed thousands of molecular dynamics simulations that make use of a highly optimized interatomic potential derived from quantum mechanics. We are able to match the published time-resolved electron diffraction data, and demonstrate that, regardless of the assumptions, considerable laser energy is transported out of the interaction region. From our results we validate various theoretical models for the electron-ion equilibration rate in warm dense gold. 1. Szymon L. Daraszewicz et al. Phys. Rev. B 88, 184101 (2013). 2. M. Z. Mo et al. Science 360, 1451 (2018). 3. R. Ernstorfer et al. Science 323, 1033–1037 (2009). [Preview Abstract] |
Friday, October 9, 2020 2:36PM - 2:48PM Live |
D02.00004: Analysis of Time Gated K-shell Ni Spectra Created by Implosion of DPWA A. Stafford, A.S. Safronova, V.L. Kantsyrev, I.K. Shrestha, V.V. Shlyaptseva Spectroscopy is a useful tool for understanding plasma. It can be used to estimate plasma conditions which when paired with time gated spectra helps characterize how plasma evolves. Double planar wire arrays (DPWAs) are a Z-pinch in which two parallel arrays of wires are imploded by passing high current through the wires. Using a load current multiplier (LCM) with the Zebra generator, a current of up to 1.9 MA can be achieved to implode the array. DPWAs composed of 12 Alumel (96{\%} Ni, 2{\%} Al, 2{\%} Si) wires per plane were imploded while time gated diagnostics including x-ray spectrometers and pinhole cameras were fielded. The time gate spectra collected from these experiments include K-shell Ni radiation that shows an evolving ionization balance with various ionization stages appearing and disappearing throughout the implosion process. Results from these experiments and modeling will be presented highlighting the value of time gate diagnostics to study atomic processes in Z-pinch plasmas. [Preview Abstract] |
Friday, October 9, 2020 2:48PM - 3:00PM Live |
D02.00005: Experiments for guiding the electron beams in the laser target using MG magnetic fields Noah Huerta, Vladimir Ivanov, Alexey Astanovitskiy Collimation of fast electrons in the laser targets by strong magnetic fields will be studied at the University of Nevada, Reno. Studies such as fast ignition concept for inertially confined fusion and medical applications would benefit from a better understanding of guiding fast electrons. Coherent transition radiation (CTR) diagnostic indicates the collimation of fast electrons by strong external magnetic fields. CTR is generated during the pass of electrons through the target on the rear side. The 1 MA Zebra pulsed power machine coupled with a 50 TW laser will be used to conduct such experiments. CTR will be generated on the backside of Si and CH targets at laser intensity of (0.3-1)x10$^{\mathrm{19}}$ W/cm$^{\mathrm{2}}$. Collimation of fast electrons will be monitored by CTR on the laser target. Targets will be placed in the axial magnetic field generated in coil loads by the Zebra pulsed power machine. The Zebra machine produces the longitudinal magnetic field of 1-1.5 MG. Initial laser experiments with CTR diagnostics will be presented. [Preview Abstract] |
Friday, October 9, 2020 3:00PM - 3:12PM Live |
D02.00006: Studying Cold Atomic Systems with Monte Carlo Simulation and Random Phase Approximation Patrick Kelly We used complementary numerical techniques to study exotic phases in a cold atomic Fermi gas, modeled with a Hubbard Hamiltonian. We focus on a system on a two-dimensional optical lattice that is at half-filling, where on average one fermion occupies each lattice site, and is spin-balanced, where equal numbers of spin-up and spin-down particles are present on the lattice. With these conditions, the system forms the elusive supersolid phase: a superfluid with a checkerboard density modulation. Using Quantum Monte Carlo (coupled with state-of-the-art analytic continuation techniques) we calculate unbiased results for the dynamical structure factor. Generalized Random Phase Approximation provides a comparison with Monte Carlo. Though it is not an unbiased method like Monte Carlo, it allows for larger calculations with finer resolution in the momentum domain. Cold atomic systems and their properties are of interest because they have been suggested as experimentally realizable models of exotic systems in nature, such as superconductors and the superfluid interiors of neutron stars. [Preview Abstract] |
Friday, October 9, 2020 3:12PM - 3:24PM |
D02.00007: Analysis of Turbulence Production and Dissipation in a Strongly Stable Stratified Boundary Layer. Amir Atoufi, K.Andrea Scott, Michael L. Waite In this study, high-resolution direct numerical simulation is employed to analyze the production and dissipation of turbulent kinetic energy for an open-channel flow subjected to strongly stable stratification. To do so, dominant length scales in production and dissipation of kinetic energy for a stably stratified open-channel flow is identified first. Then, production and dissipation are directly related to the vorticity field. Turbulence production by mean-flow shear is reformulated in terms of dominant interactions between velocity and vorticity fluctuations using divergence of the Lamb vector and the Bernoulli function. It is shown that stratification interrupts the self-sustaining process of near-wall turbulence through interfering with the regeneration of streamwise vortices. The effect of stratification on the regeneration cycle of these streamwise vortices is further studied by analyzing the transient growth of streaky structures in streamwise velocity fluctuations beneath the logarithmic layer. [Preview Abstract] |
Friday, October 9, 2020 3:24PM - 3:36PM Live |
D02.00008: Computational study of low energy excitations in cold atomic Fermi systems Kaelyn Dauer, Ettore Vitali \begin{document} The calculation of dynamical properties of quantum many-body theories is a big challenge from both the theoretical and computational point of view. In particular, the study of the density response function and the spectrum of density fluctuations in attractive Fermi gases is intriguing as a research topic due to the breaking of the U(1) symmetry. This symmetry is expected to give rise to a Nambu-Goldstone collective mode, which describes the fluctuations of the phase of the order parameter, as well as a more elusive Higgs mode, where fluctuations of the amplitude of the order parameter are described. We will present Generalized Random Phase Approximation and Quantum Monte Carlo results for dilute Fermi gases. We will show similarities and discrepancies between the two approaches, and we will discuss the implications for the physics of the system. \end{document} [Preview Abstract] |
Friday, October 9, 2020 3:36PM - 3:48PM Live |
D02.00009: Searching for New Fundamental Physics with Polyatomic Molecules Nicholas Hutzler The fact that the universe is made entirely out of matter, and contains no free anti-matter, has no explanation. While we don't understand the process that created the matter in the universe, we know that it must violate a number of fundamental symmetries, including those that forbid the existence of certain permanent electromagnetic moments. We can search for signatures of these moments via precision measurements in polar molecules, whose extremely large internal fields can significantly amplify their signatures. These effects would arise from physics beyond the Standard Model, which enables table top searches for new, symmetry-violating particles and forces. These searches currently reach into the TeV scale, and offer many routes to even higher scales. In this talk, I will discuss ongoing efforts to extend these tabletop measurements to polyatomic molecules, whose complex structure offers a unique opportunity to combine robust precision measurement techniques with advanced cooling, trapping, and control techniques. This will enable experiments with high sensitivity in a variety of new physics sectors, both leptonic via the electron electric dipole moment and hadronic via nuclear moments enhanced by deformed nuclei, and offers several routes to exploring the PeV scale. [Preview Abstract] |
Friday, October 9, 2020 3:48PM - 4:00PM |
D02.00010: Beneath The Sub Atomic Kevin Harding Behind Newton, behind quantum physics, what is, can only be identified as an indexed arrangement called: The Putare Arrangement. It explains why quantum dynamics won’t begin until its been observed. By cataloging this new field of science, break throughs in medicine, changes in reality and computational science can be anticipated and deliberately engineered to bring about a specific result. The discovery of axioms at and beneath the subatomic level led to the find. Newton explains how? Harding explains why? A new problem in physics called the Chimera Stigma demonstrates yet another bridge between nuclear physics and classical mechanics given by a new equation. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700