Bulletin of the American Physical Society
2008 APS April Meeting and HEDP/HEDLA Meeting
Volume 53, Number 5
Friday–Tuesday, April 11–15, 2008; St. Louis, Missouri
Session K1: Poster Session II (2:00-5:00pm) |
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Sponsoring Units: APS Room: Hyatt Regency St. Louis Riverfront (formerly Adam's Mark Hotel), Fourth Floor Lobby |
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K1.00001: PHYSICS EDUCATION POSTERS |
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K1.00002: Overview of the Howard University Interdisciplinary Science for Middle Schools (ISMS) Program Marcus Alfred The goals of the ISMS program are to expose science graduate students (fellows), middle school teachers, and middle school students to new perspectives and skills in STEM fields, and to create new opportunities in STEM fields for all participants. The fellows and middle school teachers in the program create and use science activities and curriculum modules for physical science, life science and environmental science middle school classes. [Preview Abstract] |
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K1.00003: ABSTRACT WITHDRAWN |
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K1.00004: Disentangling the Force Concept Inventory Using Latent Class Analysis Ivan Ivanov, Helena Dedic, Steven Rosenfield This study probes dimensionality of the Force Concept Inventory (FCI) using a latent class factor analysis of data collected at three universities (6621 records). The best fitting 5-factor model closely matches theoretical groupings of items envisioned by the FCI authors. Although this model accounts for more than 95{\%} of bivariate associations present in the data, and the p-value indicates the model is acceptable, there remain some unexplained pair-wise associations between items. This result shows that the FCI measures several abilities rather than just one. Thus, assigning separate scores to each factor may be more appropriate than the total score of correct answers. This is especially important for physics educational researchers who use the FCI to assess the effectiveness of particular pedagogies. When the scores are reported for individual records, the changes in each of the latent abilities with instruction may be rigorously measured. We have found that the pre-instruction and post-instruction scores for all three universities showed significant gains for three of the factors (understanding of Newton's 3$^{rd}$ Law, Cancelling forces/Constant forces and Gravitation). The gains in the other two factors were not statistically significant because they were below the classification error. [Preview Abstract] |
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K1.00005: Summer Institute for High School Teachers Ponn Maheswaranathan, Cliff Calloway We have conducted again a summer institute for high-school teachers in South Carolina at Winthrop University. The target audience were 9th grade physical science teachers in schools within a 50-mile radius from Winthrop. We developed a graduate level physics professional development course covering selected topics from the physics and chemistry content areas of the South Carolina Science Standards. Delivery of the material included the traditional lectures and the following innovative approaches in science teaching: hands-on experiments, group activities, computer based data collection, group discussions, and presentations. Two master teachers assisted us during the delivery of the course which took place in June 20-29, 2007 using Winthrop facilities. Requested funds were used for the following: salary for us and master teachers, contract course fee, some of the participants' room and board, startup equipment for all the teachers, and indirect costs to Winthrop University. Startup equipment included Pasco's stand-alone and portable Xplorer GLX interface and sensors (temperature, voltage, pH, pressure, motion, and sound). What we learned and ideas for continued K-12 teacher preparation initiatives will be presented. [Preview Abstract] |
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K1.00006: Investigating the Conceptual Variation of Major Physics Textbooks John Stewart, Richard Campbell, Jessica Clanton The conceptual problem content of the electricity and magnetism chapters of seven major physics textbooks was investigated. The textbooks presented a total of 1600 conceptual electricity and magnetism problems. The solution to each problem was decomposed into its fundamental reasoning steps. These fundamental steps are, then, used to quantify the distribution of conceptual content among the set of topics common to the texts. The variation of the distribution of conceptual coverage within each text is studied. The variation between the major groupings of the textbooks (conceptual, algebra-based, and calculus-based) is also studied. A measure of the conceptual complexity of the problems in each text is presented. [Preview Abstract] |
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K1.00007: Characterizing the Evolution and Variation of Major Physics Textbooks Jennifer Campbell, John Stewart The linguistic and structural properties of two major physics textbooks are compared. The structure of each textbook is measured and differences in the amount of space, words, and mathematics devoted to different parts of the text are reported. The linguistic richness of each text and each textual part is measured using LEXX. The readability of each textbook is characterized using standard readability formulas. A new readability formula that corrects for mathematics is proposed. The evolution of one of the textbooks over a fifteen year (four versions of the text) time span is also investigated. The reading difficulty of the textbook increased by approximately one-half a grade level over fifteen years. The lexical richness of the textbook also increased over the same period. [Preview Abstract] |
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K1.00008: Teaching Quantum ChromoDynamics using Rubik's Cube Wayne R. Lundberg A potential relationship between the combinatorial aspects of Quantum Chromodynamics and Rubik's cube algebra was first noted in 1982. The Scientific American cover story's mathematics failed to complete the analogy, but clearly demonstrated the value of a graphical, tangible tool for communicating the algebraic relationships of quarks in QCD. Symmetry breaking and restrictions imposed on Rubik's cube algebra were (http://arxiv.org/abs/physics/9712042) defined in a way which provides unified algebra. Construction of standard model particles as well as strong and weak interactions between quarks can be demonstrated with or without student participation. Quantum ElectroDynamics requires extension to a multi-cube superposition approach in which each particle naturally inhabits a separate cube. The three families of particles have been shown to be both necessary and sufficient. The restricted cube, symbolized by a Cyrillic Ya, is the only known non-commutative matrix algebra which passes Seiberg's causality criterion. Many topics of current research can be quickly and clearly introduced to the audience, e.g. a tripartite string (1-brane) has six intrinsic extra dimensions and is one-to-one and onto the standard model of particle physics. The restricted cube algebra has proven to be an active engagement technique well-suited to introducing QC/ED to physics students and the public. Several cubes will be available for reference and demonstrations. [Preview Abstract] |
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K1.00009: Characterizing the Effect of Written Presentation on Performance in an Introductory Physics Class Shawn Ballard, John Stewart Samples of student writing on hourly exams in an introductory science class were characterized based on important presentation features such as the number of words, sentences, mathematical expressions, and graphs. Correlation analysis is used to determine the features of student writing that most directly affect student performance in the class and student conceptual mastery of the material. Regression analysis shows that written presentation data can be used to predict student exam performance with R-squared=0.38. Student writing behavior also allows the prediction of conceptual performance with R-squared=0.20. Substantially stronger predictive power for both exam performance and conceptual mastery is obtained if time-on-task data is combined with written presentation data. [Preview Abstract] |
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K1.00010: TESTS OF PHYSICAL LAWS POSTERS |
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K1.00011: Stellar and dark matter caustics: are both visible? Robyn Sanderson Dark matter caustics formed by galaxy mergers can substantially enhance the local density of dark matter, and even more substantially enhance the gamma-ray flux from WIMP annihilations in those caustics, in some cases by several orders of magnitude. This effect raises the possibility that a high-energy gamma ray detector, such as GLAST, may be able to detect annihilation signals from extragalactic caustics. I calculate the annihilation flux for two cases where caustics are already known to exist from stellar morphology and kinematics: the classic shell galaxy NGC3293 and the shell in the Andromeda galaxy (M31) recently discovered by Fardal et al. [Preview Abstract] |
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K1.00012: General Relativistic Numerical Simulations of Coalescing Binary Neutron Stars with Adaptive Mesh Refinement Methods Jian Tao, Wai-Mo Suen, Randy Wolfmeyer, Hui-Min Zhang The poster reports the progress made in the construction of an adaptive mesh refinement enabled numerical code, GR-Astro, which enables such simulations, and its applications to the neutron star inspiral coalescences. Making use of the developments described above, we studied coalescing binary neutron star systems. [Preview Abstract] |
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K1.00013: Dark Energy and Measurements of Newton's Constant, G James Donovan The high uncertainty in G is commonly attributed to the weakness of gravity and the impossibility of shielding it. But this does not satisfy: excellent groups have measured G with well controlled, precise methods. Yet their results disagree, suggesting some unknown, uncontrolled factor is in play. What could that factor be? In a separate paper at this conference, Donovan demonstrates that cosmological Dark Energy follows from a yet-unnoticed consequence of quantum mechanics and the age of the universe. His Dark Energy field has known characteristics, allowing calculation of its gradient and the force it exerts. This talk describes a semi-classical approach to derive the equation describing the effective force that results from this energy. Like Newtonian gravity, the resulting force is proportional to mass but decreases as 1/r, not 1/r$^{2}$. This uncontrolled factor has a magnitude large enough to affect measurements of G in laboratory experiments with the size of the error depending upon the details of the apparatus. When this effect is estimated and subtracted from reported precise values of G, it accounts for most of the variation between measurements made by different groups. [Preview Abstract] |
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K1.00014: Scalar Potential Model of light John Hodge Some observations of light are inconsistent with a wave--like model. Other observations of light are inconsistent with a particle--like model. A model of light is proposed wherein Newton's and Democritus's speculations are combined with the cosmological scalar potential model (SPM). The SPM was tested by confrontation with observations of galaxy HI rotation curves (RCs), asymmetric RCs, redshift, discrete redshift, galaxy central mass, and central velocity dispersion; and with observations of the Pioneer Anomaly. The resulting model of light will be tested by numerical simulation of a photon behaving in a wave-like manner such as diffusion, interference, reflection, spectrography, and the Afshar experiment. Although the SPM light model requires more work, early results are beginning to emerge that suggest possible tests because a few predictions are inconsistent with both the current particle and wave models of light and that suggest a re-interpretation of the equations of quantum mechanics. [Preview Abstract] |
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K1.00015: PLASMA PHYSICS POSTERS |
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K1.00016: The influence of the local volume fluctuations on the equation-of-state of hot and dense plasmas David Salzmann, Dima Fisher, Avraham Barshalom, Joseph Oreg Generally, equation-of-state (EOS) of hot and dense plasmas is computed under the assumption that there is a constant volume available to every ion/atom in the plasma. In the present paper we combined two recently developed models to evaluate the influence of local density fluctuations around the ions on the corresponding EOS. The first of these is the so-called Ion Ellipsoid Model (IEM). IEM assumes that the local volume of the ion is a 3-dimensional ellipsoidal enclosure. Full description of the model is given in Ref. [1]. From IEM semi-empirical formulas were derived for the ions volume distribution function [1] for 0$<\Gamma <$16, where $\Gamma $ is the plasma coupling constant. The EOS was computed by means of the EOSTA model [2], that combines and extends the STA and INFERNO models to calculate opacities and EOS on the same footing. We will describe the model and present preliminary results indicating the effect of the volume fluctuations around the ions on EOS results. [Preview Abstract] |
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K1.00017: Structural Phases in Complex Plasmas Truell Hyde, Jie Kong, Lorin Matthews, Jorge Carmona-Reyes Dust particles imbedded within a plasma acquire a charge from collisions with free electrons and ions in the plasma. If the ratio of the inter-particle potential energy to the average kinetic energy is sufficient, the particles exhibit short to long range ordering. Interestingly, dust particles under these conditions often form vertical chains due to the influence of the wakefield produced by the streaming ions in the plasma sheath. Such particle chains are proving to be a unique diagnostic tool for investigating the physics behind the basic properties of the system. This paper will discuss recent experimental results illustrating various aspects of this phenomenon. [Preview Abstract] |
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K1.00018: Theory of the Motion of Ball Lightning Peter Handel The Maser-Soliton Theory of BL predicts the dynamics of each of the harmonic waves in the wave packet that feeds and in fact defines the Langmuir plasma soliton that is observed as BL. The frequencies in the wave packet are in a narrow window f that corresponds in the case of open air BL to the diameter of the area in which the damage caused by the final explosion of the BL is observed. This is usually of the order of $\Delta$x=30 m roughly, in rms. The corresponding wave vector interval is $\Delta$k=(1/2)(1/30m)=0.017/m in rms. At the same time, k is of the order of 6/m, yielding k/$\Delta$k=360. This pronounced line-narrowing is obtained due to the large gain of the atmospheric maser when it generates the Kapitsa standing wave. Phase differences between the waves that make up the electromagnetic field that couples with the electrostatic field of the soliton are determined by the frequency dependence of gain and dissipation. They are influenced less by the motion of the air, than by the maser dynamics and by the boundary conditions shaping the electromagnetic field, i.e. the individual photonic wave-packet. The paper presents the equations that determine the phase dynamics and therefore also the observed motion of BL. A similar phase dynamics is expected to be applicable to the special case of UFO motions. [Preview Abstract] |
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K1.00019: Nonlinear interactions, heating and turbulence associated with large amplitude Alfv\'{e}n waves in a laboratory plasma Troy Carter, David Auerbach From a weak turbulence point of view, nonlinear interactions between shear Alfv\'{e}n waves are fundamental to the turbulent energy cascade in magnetic turbulence. Motivated by this, experiments on the interaction between large amplitude Alfv\'{e}n waves are being carried out on the the Large Plasma Device (LAPD) at UCLA. Large amplitude Alfv\'{e}n waves ($\delta B/B \sim 1$\%) are generated either using a resonant cavity (the Alfv\'{e}n wave MASER\footnote{J.E. Maggs and G.J. Morales, Phys. Rev. Lett. {\bfseries 91}, 035004 (2003)}) or loop antennas. Nonlinear interactions between two copropagating kinetic Alfv\'{e}n waves have been observed\footnote{T.A. Carter, B. Brugman, {\itshape et. al}, Phys. Rev. Lett. {\bfseries 96}, 15501 (2006)}. Strong, localized electron heating during large amplitude kinetic Alfv\'{e}n wave launch is also observed. The heating results in significant gradients in the electron temperature which in turn excite unstable drift-Alfv\'{e}n waves. The drift waves then interact with the initial Alfv\'{e}n wave, leading to sidebands and spectral broadening. Details of these experimental observations will be discussed, as well as future plans for studies of nonlinear processes assocaiuted with Alfv\'{e}n waves in LAPD. [Preview Abstract] |
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K1.00020: A Simple Ion-Ion Charge Exchange Model for Kinetic Plasma Simulations David Fillmore, Peter Messmer, Paul Mullowney We present a simple modification of the semi-classical over-barrier model of ion-atom charge exchange for the case of electron transfer between positive ions. The charge exchange cross-sections have been incorporated into an electromagnetic particle-in-cell plasma model which also includes schemes for electron impact ionization and electron-ion recombination. The influence of charge exchange on the plasma ionization state is explored for selected light elements under various temperature and density regimes. [Preview Abstract] |
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K1.00021: Generation of supersonic plasma jets from pulsed-power driven exploding wire experiments Simon Bott, David Haas, Yossof Eshaq, Utako Ueda, Robert Madden, Gilbert Collins, Farhat Beg Astrophysical jets and supersonic outflows are associated with a wide range of phenomena. Determination of the processes which dominate jet behaviour can be used to infer the properties of their sources which include Young Stellar Objects (YSO) and Active Galactic Nuclei (AGN). Limited observational data makes the construction of theoretical descriptions problematic, and scaled laboratory experiments represent a useful test-bed for assessing the dominant physics. We present experiments studying the generation of plasma jets in exploding wire experiments for both x-pinch and conical configurations. These will be examined at 80 kA and 250 kA and diagnosed by laser interferometry and time-resolved self emission to infer the electron density and temperature range respectively. Estimations of the dimensionless parameters (Mach number, jet/ambient density ratio, cooling parameter) will be given for each experiment. Future studies and scaling of experiments to larger currents will be discussed. [Preview Abstract] |
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K1.00022: Evidence for an intense solar outburst in prehistory A.L. Peratt, W.F. Yao A past intense solar outburst and its effect on Earth was proposed by Gold [3] who based his hypotheses on astronomical and geophysical evidence. The discovery that objects from Neolithic or Early Bronze Ages carry patterns of high-current Z-pinches provides insight into the origin and meaning of these ancient symbols produced by mankind. A comparison of graphical and radiation data from high-current Z-pinches to petroglyphs and megaliths is made [1]. These correspond to mankind's visual observations of ancient aurora if the solar wind had increased at times between one and two orders of magnitude, millennia ago [3]. Reference [2] focused on the source of light and its temporal change from a current-increasing Z-Pinch or dense plasma focus aurora. The orientation and field-of-view (FOV) as surveyed and contributed from 139 countries, the latest data coming from a 300 km survey along the Orinoco River Basin in Venezuela, is given. A reconstruction of the auroral form is shown based on existent geophysical evidence. Shown are relativistic electron flows inward at Earth's south polar axis and hypervelocity proton impacts around the north polar axis. 1. A. L. Peratt, Trans. Plasma Sci., 31, 1192, 2003. 2. A. L. Peratt, Trans. Plasma Sci., 35, 778, 2007. 3. T. Gold, \textit{Pontificiae Academiae Scientiarvm Scripta Varia} 25, 159, 1962. [Preview Abstract] |
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K1.00023: The Case for Enhanced Transport Coefficients in Astrophysical Plasmas Steven Spangler Theoretical descriptions of astrophysical plasmas such as the solar corona, the interstellar medium, and extragalactic radio sources typically employ single fluid magnetohydrodynamics (MHD). The lack of detail in astronomical observations often disqualifies more sophisticated theories. Solutions of the MHD equations can possess agreement with observations, but only if transport coefficients such as resistivity, viscosity, and thermal conductivity are many orders of magnitude larger than independent estimates based on binary electron collisions with ions and electrons. Illustrations of this concept are Joule heating of the solar corona by observed currents and the structure of the magnetic field in the Milky Way and similar galaxies. This situation can be understood in one of two ways. (1) The MHD equations may indeed be a correct description of the dynamics of these plasmas, and the true transport coefficients are greatly enhanced over collisional values. (2) Alternatively, more complex sets of primitive equations may be needed to describe astrophysical plasmas. This paper explores possibility (1), and discusses possible mechanisms for transport coefficient enhancement, and observational tests of those mechanisms. [Preview Abstract] |
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K1.00024: Experimental study of plasma bubble expansion as a model for extragalactic radio lobes Scott Hsu, Alan G. Lynn, Yue Zhang, Wei Liu, Hui Li, Christopher Watts, Mark Gilmore Recent work in plasma astrophysics has suggested that magnetic energy features prominently in the large-scale evolution of active galaxies. The Plasma Bubble Expansion Experiment (PBEX) at UNM will conduct laboratory experiments to address outstanding nonlinear plasma physics issues related to how magnetic energy and helicity carried by extra-galactic jets interacts with the intergalactic medium to form extra-galactic radio lobe structures. A newly-built pulsed coaxial gun will form and inject magnetized plasma bubbles into a lower pressure weakly-magnetized background plasma formed by the helicon and/or hot cathode source in HELCAT, a 4~m long and 50~cm diameter linear plasma device. Plasma properties can be adjusted such that important dimensionless parameters are relevant to the astrophysical context. Ideal MHD simulations of the experiment have indicated the strong possibility of MHD shocks appearing. This poster will provide an overview of the physics goals, experimental design/status, and coordinated theory/modeling of PBEX. [Preview Abstract] |
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K1.00025: Ideal Magnetohydrodynamical Simulations of Magnetic Bubble Expansion as a model for extragalactic radio lobes Wei Liu, Scott Hsu, Hui Li, Shengtai Li, Allan Lynn Recent astronomical observations indicate that radio lobes are gigantic relaxed magnetized plasmas with kilo-to-megaparsec scale jets providing a source of magnetic energy from the galaxy to the lobes. Therefore we are conducting a laboratory plasma experiment, the Plasma Bubble Expansion Experiment (PBEX) in which a higher pressure magnetized plasma bubble (i.e., the lobe) is injected into a lower pressure background plasma (i.e., the intergalactic medium) to study key nonlinear plasma physics issues. Here we present detailed ideal magnetohydrodynamic (MHD) three-dimensional simulations of PBEX. Given reasonably low injection speeds of the magnetic bubble, its expansion due to the Lorentz force leads to one perpendicular MHD shock and one compressible reversal MHD wavefront, where three-dimensional reconnection results due to numerical resistivity. With the expansion, some angular momentum is transported from the rotating magnetic bubble to the background plasma mainly due to advection. The discovery of MHD shocks in the simulations shows that PBEX provides a rare opportunity to study MHD shocks in a laboratory experiment. Comparison of models and measurements will be used to validate the theoretical tools, which we will apply to nonlinear relaxation of magnetized plasmas in astrophysical systems. [Preview Abstract] |
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K1.00026: Statistical Theory of a Magnetized Corona above a Turbulent Accretion Disk Dmitri Uzdensky, Jeremy Goodman We present a statistical theory of a force-free magnetic field in the corona above a turbulent accretion disk. The field is represented by a statistical ensemble of loops tied to the disk. Each loop evolves under several physical processes: Keplerian shear, turbulent random walk of the disk footpoints, and reconnection with other loops. We introduce the distribution function of loops over their sizes and construct a kinetic equation that governs its evolution. This Loop Kinetic Equation is analogous to Boltzmann's kinetic equation, with loop-loop reconnection described by a binary collision integral. A dimensionless parameter is introduced to scale the overall rate of reconnection relative to Keplerian shear. We solve the loop kinetic equation numerically to obtain the steady state distribution function and also calculate self-consistently the distribution of the mean magnetic pressure and dissipation rate with height, the equilibrium shapes of loops of different sizes, and the energy and torque associated with coronal magnetic loops. We explore the dependence of these quantities on the reconnection parameter. [Preview Abstract] |
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K1.00027: 3D relaxation of flux ropes: boundary conditions, bouncing, merging, onset of reconnection T.P. Intrator, X. Sun, L. Dorf, G. Lapenta Magnetic fields in MHD plasmas also have corresponding image (ie source) currents. This situation can be represented with flux ropes, which are the building blocks of MHD plasmas. Examples that are 3D and not toroidal include in nature: Solar coronal loops, coronal holes, astrophysical jets; and in the laboratory: spheromaks, Z pinch, spacecraft thrusters, etc. For these situations, the axial boundary conditions are important. Using the Reconnection Scaling Experiment (RSX) we create an experimental laboratory model with 1, 2 or more linear flux ropes, with embedded current parallel to an external magnetic guide field. A current channel can relax via instability (e.g. kink), and we take advantage of this to revisit the notion of what line tying means. Multiple ropes mutually attract via strong, ideal MHD JxB forces. They are observed to bounce or coalesce (magnetically reconnect) depending on the speed of mutual approach. 3D relaxation occurs when flux ropes rotate about each other, while twist is transferred into writhe via the kink instability. [Preview Abstract] |
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K1.00028: Hydrodynamic and atomic-kinetic modelling of photoionised neon plasmas Iain Hall, Tunay Durmaz, Roberto Mancini, Jim Bailey, Gregory Rochau, Michael Rosenburg, David Cohen, Igor Golovkin, Joseph MacFarlane, Manolo Sherrill, Joseph Abdallah, Robert Heeter, Mark Foord, Siegfried Glenzer Photoionised plasmas are common in astrophysical environments. New high resolution spectra from such sources have been recorded in recent years by the Chandra and XMM-Newton satellites. These provide a wealth of spectroscopic information and have motivated recent efforts aimed at obtaining a detailed understanding of the atomic-kinetic and radiative characteristics of photoionised plasmas. The Z-pinch facility at the Sandia lab is the most powerful terrestrial source of X-rays and provides an opportunity to produce photoionised plasmas in a well characterised radiation environment. We present modelling work and experimental design considerations for a forthcoming experiment at Sandia in which X-rays from a collapsing Z-pinch will be used to photoionise low density neon contained in a gascell. View factor calculations were used to evaluate the radiation environment at the gascell; the hydrodynamic characteristics of the gascell were examined using the Helios-CR code, in particular looking at the heating, temperature and ionisation of the neon and the absorption of radiation. Emission and absorption spectra were also computed, giving estimates of spectra likely to be observed experimentally. [Preview Abstract] |
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K1.00029: Opacity effects on the polarization of the chlorine He-alpha line Peter Hakel, Roberto Mancini Polarization-based line spectroscopy is a valuable tool in determining the characteristics of the electron distribution functions in plasmas anisotropy is expected to be important. An example is the case of laser-produced plasmas driven by ultra-fast high-intensity pulsed lasers. Anisotropic electrons can unevenly populate magnetic sublevels of atomic energy levels resulting in partial polarization of the emitted spectral lines. Work done so far in this area has been performed in the optically-thin approximation, which typically is justified for satellite lines. However, recently this approach has been applied to resonance lines which can be optically thick under high-density conditions. Therefore we performed a modeling study of the He-alpha Cl line accounting for the effects of radiation transport on its polarization. This allows us to identify plasma regimes in which optically-thin approximation remains justified and those where opacity effects become important for this spectral line and the changes they introduce in the line polarization. [Preview Abstract] |
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K1.00030: Measurements of radiative shock properties using optical and scattering diagnostics A. Visco, R.P. Drake, M.J. Grosskopf, D.H. Froula, S.H. Glenzer, A.B. Reighard, T. Boehly, J.P. Knauer Radiative shocks are shock waves whose structure has been altered by radiation transport. Such shocks are present in numerous astrophysical systems, including supernova remnants, supernovae, and accretion disks. Recent experiments have used the Omega laser to study the shocked material in radiative shocks that are optically thin upstream and optically thick downstream. A thin slab of low-Z material is driven into a 1.1 atm. cylinder of high-Z gas at speeds over 100 km/s. producing strong radiative effects. Diagnostic techniques have included point projection radiography, Thomson scattering, and optical pyrometery, to make measurements of densities, temperatures, velocities, and the shocked layer structure. Sponsored by the Stewardship Sciences Academic Alliances program, through DOE Research Grants DE-FG52-07NA28058, DE-FG52-04NA00064, and by other grants and contracts. [Preview Abstract] |
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K1.00031: Accessing the High Energy Density Regime using Plasma Jets Jason Cassibry, Seth Thompson Plasma jets driven magnetoinertial fusion (PJMIF) is an emerging fusion energy concept which consists of an imploding liner which shock heats and compresses a magnetized target. The liner is formed by the merging of a cylindrical or spherical distribution of plasma jets, which are launched by a salvo of plasma accelerators. Confinement of the target is inertial, with the thermal conduction suppressed by the presence of the magnetic field. PJMIF is now being considered by the DOE as a path towards creating high energy density physics (HEDP) in the laboratory. In this paper, we will use analytical and smoothed particle hydrodynamic (SPH) modeling to show how the HEDP regime is accessible by converging shock waves. The primary goal is to estimate the initial conditions required for plasma liners in reaching 1 Mbar pressure using imploding shocks. Our analytical models consist of the Noh test case and of a self-similar converging shock model in which radially imploding plasma shock heats and compresses a low density core to high pressures. Both models allow calculation of conditions behind a reflected shock in cylindrical or spherical symmetry. We will use SPH to study carefully selected 2D and 3D cases based on the analytical study. [Preview Abstract] |
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K1.00032: Specular Reflection of Intense Laser Light Interacting with Solid Targets A. Link, D. Offermann, V. Ovchinnikov, D. Schumacher, L. Van Woerkom, R. R. Freeman, H. Chen, D. Hey, I. Jovanovic, S. Le Pape, A. Mackinnon, A. Macphee, P. Patel, Y. Ping, C. Chen, T. Bartel, S. Chawla, J. King, T. Ma, F. Beg, K. Akli, R. Stephens, Y. Tsui The reflectivity of high intensity laser plasma interactions is a crucial parameter in understanding laser coupling efficiency and light guiding properties of reentrant cones in fast ignition experiments. Studies of the specular reflectivity have been conducted on the Titan laser system in the Jupiter Laser Facility at Lawrence Livermore National Laboratory with solid density metal targets. Results from absolutely calibrated scatter plates will be presented for intensities of 10$^{18}$ to 10$^{20}$ Wcm$^{-2}$, pulse widths from .7 to 10 ps, $s$ and $p$ polarizations and a variety of target geometries. Specular reflectivity of $s$ polarized light at 10$^{20}$ cm$^{-2}$ increases by 4000{\%} as the incident angle is varied from 28\r{ } to 75\r{ }. [Preview Abstract] |
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K1.00033: Study of laser-created laboratory plasma jets with soft x-ray laser interferometry Jonathan Grava, Michael Purvis, Jorge Filevich, Mario Marconi, Jorge Rocca, James Dunn, Stephen Moon, Vyacheslav Shlyaptsev Jet-like plasma structures were generated by irradiating V-shaped Al targets at I=1$\times $10$^{12}$ W/cm$^{2 }$with 0.8 J Ti:Sa laser pulses of 120 ps duration. A narrow plasma plume was observed to expand from the bottom of the cavity with Mach number $\sim $ 5. The plasma jet evolution was studied using soft x-ray laser interferometry ($\lambda $= 46.9 nm), allowing electron density measurements of the 1-mm plasma that exceeded 1$\times $10$^{20}$ cm$^{-3}$. Late in the evolution the jet expands laterally and develops sidelobes as it interacts with additional material expanding from the walls. The measurements were compared with 2-D simulations from the code HYDRA to gain understanding of the mechanisms that form the narrow plasma jet, including the role of radiation cooling. Measurements of similar jets generated by irradiating targets of different Z are under way Work sponsored by NNSA-SSAA DOE Grant {\#} DE-FG52-060NA26152 and the U.S. DOE LLNL through ILSA contract No. W-7405-Eng-48. [Preview Abstract] |
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K1.00034: Laser-driven ultraintense proton beams for high energy-density physics Slawomir Jablonski, Jan Badziak, Piotr Parys, Marcin Rosinski, Jerzy Wolowski, Adam Szydlowski, P. Antici, J. Fuchs, A. Mancic The results of studies of high-intensity proton beam generation from thin (1~--~3$\mu $m) solid targets irradiated by 0.35-ps laser pulse of energy up to 15J and intensity up to 2$\times $10$^{19}$ W/cm$^{2}$ are reported. It is shown that the proton beams of multi-TW power and intensity above 10$^{18~}$W/cm$^{2}$ at the source can be produced when the laser-target interaction conditions approach the Skin-Layer Ponderomotive Acceleration requirements. The laser-protons energy conversion efficiency and proton beam parameters remarkably depend on the target structure. In particular, using a double-layer Au/PS target (plastic covered by 0.1~-- 0.2$\mu $m Au front layer) results in two-fold higher conversion efficiency and proton beam intensity than in the case of a plastic target. The values of proton beam intensities attained in our experiment are the highest among the ones measured so far. [Preview Abstract] |
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K1.00035: Temperature gradient in a solid target produced by the deposition of energy by fast electrons generated in high Intensity Short Pulse Laser matter interactions Sophia Chen, Pravesh Patel, Hyun-Kung Chung, Andreas Kemp, Sebastien Le Pape, Brian Maddox, Scott Wilks, Farhat Beg Recently systematic studies to investigate the temperature gradient in short-pulse laser irradiated solid targets. Experiments were conducted using the Titan Laser at the intensity 3 x 10$^{20}$ W/cm$^{2}$ (energy $\sim $ 140 J with a pulse duration of 500 fs). The 2.4 micron thick targets were composed of 0.4 micron copper tamped by silver on the front and aluminum on the back. Depth of the copper layer was changed systematically to study heating due to fast electrons. Copper K-shell emission of 8 - 10 keV was measured with a Highly Oriented Pyrolytic Graphite (HOPG) spectrometer. Diagnostics also include a single-photon counting camera to provide absolute K-shell photon yield. Results show a significant drop in He-alpha emission within 0.75 um from the front of the target, which indicates a rapid drop in temperature. Measurements are compared to Hydrodynamic, PIC and Atomic codes. [Preview Abstract] |
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K1.00036: The generation of warm dense matter according to numerical modeling of thick wire heating Volodymyr Makhin, Milena Angelova, Thomas Awe, Bruno Bauer, Irvin Lindemuth, Ioana Paraschiv, Richard Siemon Rad-MHD modeling with MHRDR gives insight into a UNR experiment where 900-kA with a 70-ns rise time is driven through a 1-mm-diameter aluminum rod. The skin depth is smaller than the rod radius, so the aluminum is compressed by the pinch effect. However, experimentally the surface of the rod expands radially, even while the current is increasing. Expansion is expected and observed in thin wires, where magnetic forces are small compared with the pressure generated by Ohmic heating, but expansion is somewhat surprising in thick-wire experiments because magnetic forces are so strong that compression of aluminum to over twice normal density is expected. Simulations show expansion in these experiments results when the resistivity allows a small imbalance between magnetic forces and the pressure gradient, which allows material to slip through the magnetic field. Predicting the expansion is a challenge, because the expanding aluminum is primarily in the regime of warm dense matter, in which the ion-ion coupling parameter is larger than unity, and electrical resistivity estimates are difficult. In these simulations SESAME tables are used that include resistivity estimates from recent experiments and quantum-molecular-dynamic computations. [Preview Abstract] |
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K1.00037: Laboratory Experiments to Study Plasma Jet and Shock Using High-Power Lasers Youichi Sakawa, S Dono, Y. Kuramitsu, T. Kato, T. Kimura, K. Miyanishi, T. Endo, N. Ozaki, H. Nagatomo, K. Shigemori, R. Kodama, T. Norimatsu, H. Takabe, J. Waugh, N. Woolsey, B. Loupias, M. Koenig We describe laboratory laser-plasma experiments to form plasma jets and study jet driven shocks. Particular questions that are of interest are the formation and collimation of these jets, the relevance of experiment to astrophysical jets, and the formation of collisionless shock waves. The experiments were performed with Gekko XII HIPER laser system (3w, 500 ps, $\sim $10$^{15}$ W/cm$^{2})$ at the Institute of Laser Engineering, Osaka Univ. Several types of targets were explored. The plasma jet and shock were measured with a side-on Mach-Zender interferometry diagnostic, and rear-surface self-emission diagnostics. These diagnostics enable the jet shape, electron density and temperature to be inferred. [Preview Abstract] |
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K1.00038: Shaped mass limited target acceleration by ultra high intensity laser pulses Alexander Andreev, Konstantin Platonov Ultrahigh intensity (UHI) laser pulses may accelerate ions in thin targets to big energies and highly collimated ion beams may be formed. In order to avoid the slowly moved regions of a larger foil as charge separation effects it has been proposed to use a small target with radius about laser spot size, so named mass limited target (MLT). Ion acceleration in targets irradiated by short ultra-intense laser pulses has been studied with analytical model and 2D3V PIC simulations, which describe the complete process from the electron acceleration in the laser field to the ion bunch formation. Simulations were performed for sub $\mu$m-scale sizes plane targets (foils and foil sections) and curve foil sections. Energy spectra of fast ions, laser conversion efficiency to fast ions and the divergence of ion beams are compared for various types of targets. When MLT is irradiated by UHI laser pulse, the resulting pellet plasma is strongly accelerated forward. The kinetic energy of the ions in the bunch's densest region can exceed tens MeV at about solid density. The regime of a most effective acceleration is realized in the case when laser field is about electrostatic field of ion core of MLT. It is found that maximal ion energy can be significantly enhanced by choosing of MLT instead of foil of the same thickness. [Preview Abstract] |
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K1.00039: Preheat measurement in the laser irradiated targets Kazuto Otani, Keisuke Shigemori, Tatsuhiro Sakaiya, Atsushi Sunahara, Yoichi Sakawa, Mitsuo Nakai, Hiroyuki Shiraga, Hiroshi Azechi, Kunioki Mima We measured the temperature at the rear surface of the planar target. The target preheating is the crucial problem for the experimental researches with the high power laser irradiation. Especially, the fuel preheating can decrease the compression performance of the inertial confinement fusion targets. We applied two types of targets, one is simple foil of polyimide, and another is cryogenic liquid deuterium (LD$_{2})$ target. They are corresponding to the ablator and the fusion fuel in ICF target. The cryogenic LD$_{2}$ target was sandwiched by thin polyimide foils in both sides of laser irradiation. We observed the self emitting light from the rear surface of the target. When the target is assumed blackbody, the spectrum of emission shapes Planck distribution and tells its temperature. The laser irradiated in the wavelength of 2$\omega $ or 3$\omega $ to observe the difference of the effect of preheat by changing the laser wavelength. The preheat target was observed by optical pyrometer and VISAR. We will show the experimental results in the presentation. [Preview Abstract] |
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K1.00040: Plasma-hydro coupling in cassio, an Inertial Confinement Fusion Code from the Crestone Project Thomas Masser, John Wohlbier The Crestone Project at Los Alamos National Laboratory produces cassio, an ICF code. Currently cassio implements radiation hydrodynamics on an Eulerian AMR mesh along with a three temperature (3T) plasma physics model. A 3T model treats a plasma as a single species fluid with separate electron and ion temperatures, and uses a radiation diffusion model, where a radiation temperature characterizes the radiation energy density. The evolution equations for the electron and ion specific internal energies contain nonconservative products ($p\nabla \cdot u)$, which requires an assumption about shock jump conditions. Assuming an isentropic discontinuity in electron quantities at the shock permits semi-analytical solutions for simple fully ionized flows; these flows exhibit differential shock heating of the electrons and ions with relaxation to a common temperature. We have developed an Eulerian Godunov-based scheme for computing such shocks. We provide details for the model, method, and semi-analytic solutions, and compare results of the method to the semi-analytic solutions. [Preview Abstract] |
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K1.00041: Superintense ion beam with high energy density Vadim Dudnikov, Galina Dudnikova The energy density of ion beam accumulated in a storage ring can be increased dramatically with using of space charge compensation as was demonstrated in experiments [1]. The intensity of said superintense beam can be far greater than a space charge limit without space charge compensation. The model of secondary plasma build up with secondary ion-electron emission as a source of delayed electrons has been presented and discussed. This model can be used for explanation of bunched beam instability with electron surviving after gap, for prediction of e-cloud generation in coasting and long bunches beam, and can be important for pressure rise in worm and cold sections of storage rings. A fast desorption by ion of physically adsorbed molecules can explain a ``first pulse Instability''. Application of this model for e-p instability selfstabilization and superintense circulating beam accumulation is considered. Importance of secondary plasma for high perveance ion beam stabilization in ion implantation will be considered. Preliminary results of simulation of electron and ion accumulation will be presented. [1]. Belchenko et al., Xth International Particle Accelerator Conference, Protvino, 1977, Vol. 2, p. 287. [Preview Abstract] |
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K1.00042: Multiview core imaging of OMEGA direct-drive implosions T. Nagayama, R. Mancini, R. Tommasini, J. Koch, J. Delettrez, S. Regan, V. Smalyuk We discuss the observation and data analysis of OMEGA direct-drive implosion cores based on data recorded with three identical multi-monochromatic x-ray imagers. These instruments observed the implosion core along three quasi-orthogonal lines-of-sight, and recorded gated images of the core. The targets were plastic shells filled with deuterium gas and a tracer amount of argon for diagnostic purposes. Core imaging was based on argon Ly$\alpha $, He$\beta $ and Ly$\beta $ line emission. The data analysis rely on detailed spectral models that take into account non-equilibrium atomic kinetics, Stark broadened line shapes, and radiation transport calculations and a search and reconstruction technique based on a novel application of Pareto genetic algorithms to plasma spectroscopy. The spectroscopic analysis yields the spatial profiles of temperature and density in the core at the collapse of the implosion. [Preview Abstract] |
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K1.00043: EUV emission of warm dense plasma on an aluminum surface driven by a pulsed MG field Stephan Fuelling, Bruno S. Bauer, Richard E. Siemon, Thomas J. Awe, Volodymyr Makhin, Tasha Goodrich, Andrew Oxner, Radu Presura Plasma formation on an aluminum surface in the vicinity of high pulsed magnetic fields is studied using the UNR 1 MA Zebra generator. This physics is important in a number of applications including magneto-inertial fusion. A variety of 1-mm diameter loads with different contact configurations were tested to minimize or inhibit plasma initiation due to contact arcing. The rod diameter was larger than the skin depth for the 70-ns current rise. The rods were monitored by an array of AXUV photodiodes with directly deposited filters to record plasma emissions in the extreme ultraviolet (EUV). Other diagnostics included optical imaging to a time-gated intensified CCD camera and a streak camera, magnetic field probes, photodiodes, photomultipliers, and laser schlieren and shadowgraphy. These yielded information on the threshold for plasma formation, the expansion of the aluminum, the temperature at the surface, and the growth of the unstable {\$}m{\$}=0 mode. The relatively simple experimental setup was chosen to allow comparison with 1-D and 2-D rad-MHD modeling. [Preview Abstract] |
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K1.00044: Simple Map in Action-Angle Coordinates. Olivia Kerwin, Alkesh Punjabi, Halima Ali The simple map is the simplest map that has the topology of a divertor tokamak. The simple map has three canonical representations: (i) the natural coordinates - toroidal magnetic flux and poloidal angle (\textit{$\psi $,$\theta $}), (ii) the physical coordinates - the physical variables ($R,Z)$ or ($X,Y)$, and (iii) the action-angle coordinates - (\textit{J,$\Theta $}) or magnetic coordinates (\textit{$\Psi $, $\Theta $}). All three are canonical coordinates for field lines. The simple map in the ($X,Y)$ representation has been studied extensively $^{1, 2}$. Here we analytically calculate the action-angle coordinates and safety factor $q$ for the simple map. We construct the equilibrium generating function for the simple map in action-angle coordinates. We derive the simple map in action-angle representation, and calculate the stochastic broadening of the ideal separatrix due to topological noise in action-angle representation. We also show how the geometric effects such as elongation, the height, and width of the ideal separatrix surface can be investigated using a slight modification of the simple map in action-angle representation. This work is supported by the following grants US Department of Energy - OFES DE-FG02-01ER54624 and DE-FG02-04ER54793 and National Science Foundation - HRD-0630372 and 0411394. [1] A. Punjabi, H. Ali, T. Evans, and A. Boozer, \textit{Phys Lett A,} \textbf{364} 140-145 (2007). [2] A. Punjabi, A. Verma, and A. Boozer, Phys.Rev. Lett. \textbf{69}, 3322 (1992). [Preview Abstract] |
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K1.00045: Effect of elongation in divertor tokamaks Morgin Jones, Halima Ali, Alkesh Punjabi Method of maps developed by Punjabi and Boozer [A. Punjabi, A. Verma, and A. Boozer, Phys.Rev. Lett. \textbf{69}, 3322 (1992)] is used to calculate the effects of elongation on stochastic layer and magnetic footprint in divertor tokamaks. The parameters in the map are chosen such that the poloidal magnetic flux $\chi _{SEP}$ inside the ideal separatrix, the amplitude $\delta $ of magnetic perturbation, and the height $H$ of the ideal separatrix surface are held fixed. The safety factor $q$ for the flux surfaces that are nonchaotic as a function of normalized distance $d$ from the O-point to the X-point is also held approximately constant. Under these conditions, the width $W$ of the ideal separatrix surface in the midplane through the O-point is varied. The relative width $w$ of stochastic layer near the X-point and the area $A$ of magnetic footprint are then calculated. We find that the normalized width $w$ of stochastic layer scales as $W^{-7}$, and the area $A$ of magnetic footprint on collector plate scales as $W^{-10}$. [Preview Abstract] |
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K1.00046: Spectroscopy of Highly Charged Ions at the NIST Electron Beam Ion Trap Facility John Gillaspy, Ilija Draganic, Joshua Pomeroy, Yuri Ralchenko, Joseph Reader, Eric Silver ~We will report on progress in the spectroscopy of highly charged ions which has recently taken place at the NIST Electron Beam Ion Trap Facility.~ This work is focused on the areas of laboratory astrophysics and fusion energy plasma diagnostics.~~ [Preview Abstract] |
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K1.00047: Constructions of non-equilibrium plasma model and applications to LHD/Solar plasmas Norimasa Yamamoto, Takako Kato, Kuninori Sato, Hisamichi Funaba, Chihiro Suzuki, Naoki Tamura, Daiji Kato, Hiroyuki Sakaue, Nobuyuki Nakamura, Peter Beiersdorfer, Jaan Lepson, Hiroaki Nishimura, Tetsuya Watanabe HINODE satellite has high precise and high resolution EUV spectrometer, which is called EIS. Two bands of 170-210A and 250-290A are measured by EIS and measurements of many iron lines from Fe VIII to Fe XXIV are expected. In order to analysis of spectral lines from solar plasmas, which is non-equilibrium plasma, the development of non-equilibrium plasma model is necessary. In this paper, our constructed collisional-radiative model to assume quasi-steady states is applied to laboratory plasmas of LHD (Large Helical Device) and EBIT (Electron Beam Ion Trap). Then it's applied to solar plasma by EIS/HINODE. Particularly, line intensities of Fe XIII (196-210A), which have strong density dependence, are studied about temperature/density dependence and atomic data sets dependence. [Preview Abstract] |
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K1.00048: Plasma Formation on the Surface of mm-Diameter Aluminum Rods by Pulsed Megagauss Magnetic Field Thomas Awe, Richard Siemon, Bruno Bauer, Stephan Fuelliing, Vlad Makhin, Irv Lindemuth Megagauss magnetic field is pulsed on millimeter-diameter aluminum rods resulting in heating inside the skin depth, and plasma formation in a thinner layer at the surface.~ Driven by the University of Nevada, Reno-Nevada Terawatt Facility's (UNR-NTF) 2TW Zebra Z-pinch, 1.0 MA is delivered to the load, rising to current maximum in $\sim $100ns.~~ The load radius is chosen to be larger than the skin depth, placing the experiment in the 'thick wire' regime.~ In contrast to a thin uniform-current- density exploding wire, a thick wire exhibits plasma and magnetic pressure balance during current rise.~ Free expansion is limited, resulting in~high energy density and temperature.~ ~ The experiment is designed to limit large scale instability growth until after peak field. ~ During current rise, dynamic equilibrium is achieved for some 10's of nanoseconds and quasi-stable aluminum plasma heated to over 10 eV is held between a 3-5 megagauss magnetic field and a cool, dense, liquid aluminum wall.~ Preliminary understanding of the evolution of the rod interior and surface plasma is detailed with both experimental and computational results.~ Plans for future experiments, including new load designs and diagnostics under development, are given. [Preview Abstract] |
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K1.00049: Yukawa Monte Carlo (YMC) and Orbital Free Molecular Dynamics (OFMD) approaches for the eos of warm dense iron plasma Dominique Gilles, Flavien Lambert, Jean Clerouin Yukawa Monte Carlo and Molecular Dynamics simulations are powerful techniques extensively used to compute plasma properties such as EOS or transport coefficients, but are limited to applications where the linear electronic screening assumption is valid (1). Recently we have shown that a modified scheme using density functional theory with a Thomas-Fermi kinetic energy functional for the electrons (OFMD) may be well suited to perform MD simulations at high densities and temperature, without any assumption on the electronic screening (2). For selected iron plasma conditions representative of warm and dense matter, we shall compare pressure results calculated using YMC and OFMD codes and QEOS (3) and Sesame EOS models (4) and discuss the influence of keys parameters, like ionization in Yukawa theory. \newline References: [1] D. Gilles, O. Peyrusse, JQSRT 53, 6, 1995.~;Caillol J-M, Gilles D., J. Stat Phys. \textbf{100}, N5/6, 905-947, 2000; Caillol J-M, Gilles D., J. Phys. A \textbf{36}, 6243, (2003)~; A. Potekhin, G. Chabrier, Gilles, PRE \textbf{65}, 036412, 2002. [2] D. Gilles, F. Lambert, J. Cl\'{e}rouin, S. Mazevet, Gwena\"{e}l Salin, HEDP 3, 95-98, 2007; F. Lambert, J. Cl\'{e}rouin, S. Mazevet, D. Gilles, Plama Physics\textbf{, 47},4-5, 272-280(2007). [3] R.M. More, Lawrence Livermore Laboratory Report, UCRL-84991, (1981). [4] G.I. Kerley, User's Manual for PANDA~: A computer Code for calculating Equation of State, Los Alamos National Laboratory, 1981 (LA8833). [Preview Abstract] |
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K1.00050: FEW BODY SYSTEMS POSTERS |
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K1.00051: Manifestly covariant three-body bound state calculations Pieter Maris Two-body bound states can be described by the homogeneous Bethe-Salpeter equation. Analogously, three-body bound states can be described by a homogeneous integral equation for the bound state amplitudes. In ladder truncation, one can solve these body bound state equations numerically, without any further approximations. I show result for explicitly covariant calculations of bound states of three scalar particles and of bound states of two scalars and one fermion. I compare my results to a commonly used approximation to the Faddeev equation: namely a reduction to a bound state of a single particle and a (bound) two-particle state. [Preview Abstract] |
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K1.00052: Relativistic Dynamics of Quasistable States: The Bakamjian-Thomas Construction Sujeev Wickramasekara We study a synthesis of the $S$-matrix description of resonances with the Bakamjian-Thomas (BT) construction of incorporating interactions into a system of relativistic quantum particles. The BT-construction does not assume the existence of local fields mediating interactions. Therefore, it constitutes a theoretical framework more general than that of quantum field theories and is also devoid of many of the mathematical and conceptual difficulties of the latter. Characterization of resonances by the poles of the $S$-matrix has many advantages, foremost among which is perhaps the gauge invariance of the definitions of mass and width, a problem with which the field theoretical definitions suffer. Our construction shows that there exists irreducible representations of the semigroup of fundamental causal transformations of the relativistic spacetime that provide a description of relativistic resonances. These representations are generated by the interaction-incorporating Poincar\'e Lie algebra obtained from a suitable BT-construction and are characterized by the $S$-matrix complex pole position and spin of the resonance. [Preview Abstract] |
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K1.00053: Three body covariant, nonperturbative, relativistic scattering calculations using LMNP Marcus Alfred Using a formalism developed by Lindesay, Markevich, Pastrana, and Noyes, scattering cross sections and amplitudes are calculated. Comparisons are made with experiments and other studies. [Preview Abstract] |
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K1.00054: Is There A Mechanics of Mind? Robert Jones In his book ``Extending Mechanics to Minds'' (Cambridge U. Press, 2006) Jon Doyle suggests that the human mind operates according to mechanical principles. Now in contemporary cognitive science operations in the cognitive or ``knowledge level'' are performed by lower level components of the program level. This decomposition continues from the program level down through the logic level, circuit level, and device level. Each level has its own components and each is described by its own laws of operation (Unified Theories of Cognition, Allen Newell, Harvard U. Press, 1990). The circuit and device levels could just as easily by fabricated out of mechanical elements such as linkage differentials and racks and pinions (Mechanisms and Dynamics of Machinery, Mabie and Ocvirk, John Wiley and Sons, 1975, ch. 8). These mechanisms would then be exactly those governed by the mechanical principles that Doyle focuses on. But Doyle's mistake is to apply the same laws to the cognitive level. Rather, I believe, the cognitive level is best described by operations like knowledge base search, analogy, classification, compression, etc. (R. Jones, Trans. of the Kansas Acad. of Sci., vol. 109, no. 3/4, pg 159, 2006). [Preview Abstract] |
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K1.00055: BEAM PHYSICS POSTERS |
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K1.00056: G4Beamline Particle Tracking for Muon Beam Lines Kevin Beard, Rolland Johnson, Thomas Roberts The development of bright muon beams, which are needed for muon colliders and neutrino factories and are usually required to pass through matter, is limited by the lack of user-friendly numerical simulation codes that accurately calculate scattering and energy loss in matter. Geant4 is an internationally supported tracking toolkit that was developed to simulate particle interactions in large detectors for high energy physics experiments, and includes most of what is known about the interactions of particles and matter. Geant4 has been partially adapted in a program called G4beamline (G4BL) to develop muon beam line designs. We are continuing the development of G4BL to enhance its graphical user-interface and add other features to the program to facilitate its use by a larger set of beam line and accelerator developers. We describe the set of around thirty users currently using the program. [Preview Abstract] |
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K1.00057: Propagation of electron and positron beams in long, dense plasmas Patric Muggli, Brent Blue, Chris Clayton, Franz-Joseph Decker, Mark Hogan, Chengkun Hunag, Chan Joshi, Tom Katsouleas, Wei Lu, Warren Mori, Caollionn O'Connell, Robert Siemann, Dieter Walz, Miaomiao Zhou Electron beams with density larger than the plasma density can propagate through plasmas without significant emittance growth. The electron beam expels the plasma electrons from the bunch volume and propagate in a pure, uniform ion column. In contrast, positron beams attract plasma electrons that flow through the positron bunch. As a result the plasma focusing force is nonlinear, a charge halo forms around the bunch, and the bunch emittance grows. After some distance into the plasma, the bunch emittance reaches an approximately constant value, and the beam and the plasma focusing force reach a steady state. Experimental results obtained with electron and positron bunches, as well as numerical simulation results will be presented. [Preview Abstract] |
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K1.00058: Characteristic Behavior and Scaling Studies of Self Organized InP Nano-dots formed via keV and MeV irradiations Dipak Paramanik, Shikha Varma The controlled formation of nano-dots, using ion beams as tool, has become important as it offers a unique method to generate non-equilibrium phases with novel physical properties and structures with nano-dimensions. We have investigated the creation of self assembled nano- dots on InP(111) surfaces after 3 keV as well as 1.5 MeV ion beams at a large range of fluences. We have studied the Scaling exponents of the evolved surfaces by utilizing the technique of Scanning Probe Microscopy (SPM). At keV energies ripening of the nano-dots is seen below a critical time whereas an inverse ripening is observed for longer durations. At the critical time square shaped array of nano --dots are observed. The dots are characterized by narrow height and size distributions. Nano dots have also been observed at MeV ion irradiations. Their size distribution though broad at lowest fluence decreases for larger fluences. [Preview Abstract] |
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K1.00059: Generation of Electron Microbunches Trains with Adjustable Sub-picosecond Spacing. Patric Muggli, Vitaly Yakimenko, Themos Kallos, Marcus Babzien, Karl Kusche We demonstrate that trains of subpicosecond electron microbunches, with subpicosecond spacing, can be produced by placing a mask in a region of the beam line where the beam transverse size is dominated by the correlated energy spread. The particles are selected based on the scattering of their emittance at the mask. The experiment was performed with the Brookhaven National Laboratory Accelerator Test Facility 60 MeV beam. We show that the number, length, and spacing of the microbunches can be controlled through the parameters of the beam and the mask. Trains with one to eight equidistant microbunches have been produced. The microbunches spacing was adjusted in the 100 to 300 $\mu $m or 300 fs to 1 ps range. The train structure is measured using CTR interferometry. Such microbunch trains can be further compressed and accelerated, and have applications to free electron lasers (FELs) and plasma wakefield accelerators (PWFAs). [Preview Abstract] |
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K1.00060: NUCLEAR PHYSICS POSTERS |
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K1.00061: Investigations toward the possible use of energy from isomeric nuclei. Marc Litz, George Merkel, Nino Pereira, James Carroll The high energy density of some isomeric nuclei would be very attractive in energy storage applications if it could be extracted and converted to electricity conveniently and efficiently. These concepts were critically discussed in our presentation last year, but at that time no experimental results were available. This paper presents the results obtained in connection with irradiating two isomers, 177Lu and 166Ho, with nominally 2 MV bremsstrahlung from a linear accelerator. Results include verification of the end point energy and the associated dosimetry, and changes in the samples' activities and their causes. [Preview Abstract] |
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K1.00062: Status of the Charged Pion Production Cross Section Measurements at MIPP Gural Aydin The MIPP (Main Injector Particle Production) Experiment is a fixed target experiment at Fermilab to measure hadronic production for different targets and beam energies. Data were taken in 2005 on targets including aluminum, beryllium, bismuth, carbon, copper, and uranium, a cryogenic hydrogen target, and the NuMI target using six types of beam particles (pion, kaon, and proton of both charges) for the beam energies ranging from 5 GeV/c to 120 GeV/c. The MIPP experiment used Fermilab Main Injector protons as 120 GeV/c beam. We present the status of the charged pion production cross section measurements of 58 GeV/c and 120 GeV/c proton beam on a thin carbon target in terms of final state particle's longitudinal and transverse momenta. [Preview Abstract] |
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K1.00063: RADIATION SOURCES POSTERS |
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K1.00064: A Solid Oxygen Ultra-Cold Neutron Source Christopher Lavelle, Chen-yu Liu, Yun Shin Ultra-Cold Neutrons (UCN) are produced in super-thermal sources via a single inelastic down scattering event of a low energy neutron in a medium. Solid deuterium and liquid helium are the primary sources of UCN for fundamental physics research due to very low absorption cross-sections and good transparency to UCN. Solid Oxygen is an attractive alternative because it has a lower absorption cross-section and theoretically higher potential to down scatter cold neutrons to the UCN energy regime via magnon excitation. A solid oxygen source could then produce higher densities of UCN in a larger volume, enhancing the UCN flux available to experiments by as much as an order of magnitude. We present an apparatus for testing UCN production in a cold neutron beam such as at Los Alamos Neutron Scattering Center as well as a proposed UCN source based on solid oxygen for Indiana University. [Preview Abstract] |
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