Bulletin of the American Physical Society
2011 Fall Meeting of the APS Ohio-Region Section
Volume 56, Number 8
Friday–Saturday, October 14–15, 2011; Muncie, Indiana
Session EA: Applied Physics and Astrophysics |
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Chair: Feng Jin, Ball State University Room: Cooper Science CP144 |
Saturday, October 15, 2011 8:30AM - 8:42AM |
EA.00001: Using Markov Chain Monte Carlo Simulation for Heat Conduction Problems Jozef Gembarovic In our Damped Heat Wave (DHW) algorithm for calculation of temperature distribution in a one-dimensional finite medium, the space and time is discretized using $N$ nodal points with steps $\Delta x$ and $\Delta t.$ Heat propagates through the medium due to temperature differences between divisions. At any instant of time a certain portion (given by the inner heat transfer coefficient) of the excessive heat energy moves from one division to its neighbour division thus lowering temperature difference between those two divisions. We will show that our DHW algorithm represents a special case of \textit{time-space} Markov Chain Monte Carlo (MCMC) simulation with a simple random number generator for the redistribution sequence. This is a very unique and distinctive feature. All today existing numerical methods used in heat conduction calculations (e.g. explicit or implicit finite differences method, finite elements methods, etc.) are Markov Chains in time, but not simultaneously in space. We will show that in a general case, when we choose a different random number generator for the redistribution sequence, with randomly chosen neighbor, with the inner heat transfer coefficient also a random number drawn from Gaussian distribution, the MCMC simulation is rapidly converging to the analytical solution of transient heat conduction equation. [Preview Abstract] |
Saturday, October 15, 2011 8:42AM - 8:54AM |
EA.00002: Thermionic cooling on barium strontium coated CNT thin film surface Feng Jin Strong thermionic emission was observed from low-work-function barium strontium oxide coated CNT thin films. Such strong thermionic emission resulted a large cooling effect on the emitting surface. Temperature drops as high as 90 \r{ }C was obtained. Barium strontium oxide [(BaSr)O] thin films approximately 1 $\mu $m in thickness were deposited on CNT thin film grown on tungsten substrates using RF magnetron sputter deposition. Thermionic emission from the thin film was characterized and the work function of the thin film was measured using Richardson line method. The temperature drop or cooling of the thin film surface at different emission current was measured using a high precision optical pyrometer. [Preview Abstract] |
Saturday, October 15, 2011 8:54AM - 9:06AM |
EA.00003: LSP modeling of ultra-intense lasers on cone-coupled wire targets: effect of cone thickness Chris Orban, Vladimir Ovichinnikov, Kramer Akli, Anthony Link, Douglass Schumacher, Richard Freeman Experiments with ultra-intense laser pulses incident on cone-coupled wire targets can potentially yield valuable information on the physics relevant to the fast ignition fusion regime. Using the Particle-In-Cell code LSP, we present simulations with fully consistent laser E \& B fields and over 60 million fully kinetic particles designed to model mm-scale cone-wire experiments conducted with the Titan laser at LLNL. Focusing on Cu K$_\alpha$ x-ray line emission -- an informative diagnostic of the population of hot electrons -- we investigate and explain the strong experimental trend that the irradiation of thicker cones produces fewer Cu K$_\alpha$ photons. Comparison to other studies and implications for the feasibility of the fast ignition fusion concept are discussed. [Preview Abstract] |
Saturday, October 15, 2011 9:06AM - 9:18AM |
EA.00004: Using K$_{\alpha }$ images to measure pre-plasma and electron refluxing in intense laser experiments V.M. Ovchinnikov, D.W. Schumacher, L.D. Van Woerkom, K.U. Akli, R.R. Freeman We report the first use of the \textit{spatial structure} of time-integrated K$_{\alpha }$ images to \textit{quantitatively} characterize the pre-plasma profile near the critical surface and to verify unambiguously the near elimination of back-surface refluxing from targets when a thick layer of a low-Z material is attached to the back. The simulated K$_{\alpha }$ images are found to be sensitive to the pre-plasma scale length (the only free parameter in our simulations), permitting the pre-plasma profile to be determined by fitting to experimental results. Based on this ``preplasma diagnostic'', two experiments from the Titan laser at LLNL were benchmarked with the LSP simulations which allowed extracting the scale lengths for the preplasma conditions that existed at the time of the experiment. We also find that electron beam divergence angle has a linear dependence on the preplasma scale length and it increases by approximately 8 degrees per every micrometer of the preplasma scale length in the 1-5 $\mu $m scale length range. [Preview Abstract] |
Saturday, October 15, 2011 9:18AM - 9:30AM |
EA.00005: Galaxy Evolution Through Mutual Interactions Robert Berrington The hierarchical structure formation model predicts that a galaxy will be found in different environments throughout its evolutionary history. How each environment will, through numerous mechanisms, impact the structural and dynamical evolution of its constituent galaxies is unknown. We present numerous N-body simulations to investigate the change in mass, energy and structure of galaxies through mutual interactions. We discuss our investigation into the dependency of the mass and energy change with galaxy structural parameters resulting from these mutual interactions. It is our intent to characterize the effects of mutual interactions on galaxy structural parameters and thereby isolate from the effects resulting from the cluster environment. We suggest that these models can be used to look for secular trends in the observational properties of elliptical galaxies in clusters of galaxies. We discuss the preliminary results of these models, and future directions of this study. [Preview Abstract] |
Saturday, October 15, 2011 9:30AM - 9:42AM |
EA.00006: Krypton Removal in support of LUX Tom Coffey There are a number of experiments looking for experimental evidence for dark matter in the form of Weakly Interacting Massive Particles (WIMPs). The large underground xenon (LUX) experiment is a leading dark matter experiment in N. America. LUX is comprised of a time projection chamber filled with liquid xenon and faces a number interesting technical challenges. One of these is reducing the primary internal background risk posed by trace krypton, and its radioactive isotope, $^{85}$Kr, which is a beta emitter. An update of the Case krypton-xenon separation program will be presented. [Preview Abstract] |
Saturday, October 15, 2011 9:42AM - 9:54AM |
EA.00007: A New Viewpoint (The expanding universe, Dark energy and Dark matter) Daniel Cwele Just as the relativity paradox once threatened the validity of physics in Albert Einstein's days, the cosmos paradox, the galaxy rotation paradox and the experimental invalidity of the theory of dark matter and dark energy threaten the stability and validity of physics today. These theories and ideas and many others, including the Big Bang theory, all depend almost entirely on the notion of the expanding universe, Edwin Hubble's observations and reports and the observational inconsistencies of modern day theoretical Physics and Astrophysics on related subjects. However, much of the evidence collected in experimental Physics and Astronomy aimed at proving many of these ideas and theories is ambiguous, and can be used to prove other theories, given a different interpretation of its implications. The argument offered here is aimed at providing one such interpretation, attacking the present day theories of dark energy, dark matter and the Big Bang, and proposing a new Cosmological theory based on a modification of Isaac Newton's laws and an expansion on Albert Einstein's theories, without assuming any invalidity or questionability on present day cosmological data and astronomical observations. [Preview Abstract] |
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