Bulletin of the American Physical Society
APS April Meeting 2012
Volume 57, Number 3
Saturday–Tuesday, March 31–April 3 2012; Atlanta, Georgia
Session K1: Poster Session II: Sherwood I and APS Posters II (2:00 pm - 5:00 pm) |
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Room: Grand Hall West |
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K1.00001: SHERWOOD POSTERS I |
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K1.00002: Gyrokinetic Particle Simulation of Kinetic Alfven Wave Turbulence Onnie Luk, Xi Cheng, Peter Porazik, Zhihong Lin The previous studies of spectral cascade in Alfvenic turbulence clearly show signs of plasma heating, and there are several highly-debated explanations to this phenomenon. We have developed a nonlinear gyrokinetic particle simulation to study the perpendicular spectral cascade caused by Landau damping of kinetic Alfven wave, which is one of those possible heating mechanisms. The nonlinear gyrokinetic code includes scalar potential, vector potential, and compressional magnetic perturbation to form a complete, self-consistent nonlinear simulation. We will discuss the simulation results in comparison with the earlier simulation, which excludes the compressional magnetic perturbation. [Preview Abstract] |
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K1.00003: Scale-dependent anistropy in gyrokinetic turbulence Anjor Kanekar, William Dorland Eddies in Alfvenic turbulence get progressively more anisotropic with respect to the \textit{local} magnetic field. This has been recently observed in a gyrokinetic simulation [Howes et. al., PRL, 107:035004:2011, TenBarge \& Howes, eprint arXiv:1201.0056]. However, the nature of cascade for slow modes in an Alfvenic turbulent bath is still unclear. We present theory and numerical results from AstroGK exploring the nature of this cascade. [Preview Abstract] |
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K1.00004: Anisotropic turbulence of pseudo Alfv\`en waves Natalia Tronko, S\'ebastien Galtier, Sergey Nazarenko In this work we are considering the weak turbulent regime of two dimensional MHD system by applying the wave-kinetic formalism developed in the works [1,2]. Due to the geometry constraints in the two dimensional case only the Pseudo Alfv\`en Waves(PAW) can exist. We find that the turbulent behavior of the MHD system into the two dimensional case is crucially different from its behavior in three dimensional one previously considered in [3]. We show that there is no Kolmogorov-like solutions, no energy cascade and therefore no turbulence universality. We also show that the triad interactions of the PAW are not empty and lead to the derivation of the wave-kinetic equation for the energy spectrum. The important property of this equation is its simplicity and therefore the possibility to treat it analytically. In particular we consider two cases: with uniform friction and viscous friction. In the first case the analysis can fully be done analytically, at the second one we proceed with qualitative and numerical tools. The main results of this work are summarized in [4].\\[4pt] [1] Zakharov V.E.et al,Kolmogorov spectra of turbulence1,Springer 1992\\[0pt] [2] Nazarenko S.V. Wave turbulence, Springer 2010\\[0pt] [3] Galtier et al,J.Plasma Phys., 2000,63(5), pp.447-488\\[0pt] [4] Tronko N.et al,in preparation [Preview Abstract] |
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K1.00005: Simulations of collisional Trapped-Electron-Mode turbulence with the global gyrokinetic $\delta f$ Particle-in-Cell code ORB5 Thibaut Vernay, Stephan Brunner, Laurent Villard, Ben McMillan, Alberto Bottino Global collisional gyrokinetic simulations of Trapped-Electron-Mode (TEM) instabilities, for which the drive is the electron temperature gradient, are presented. The numerical tool is the Particle-In-Cell code ORB5, upgraded with linearized electron collision operators. Electrons are treated according to the so-called hybrid model, considering kinetic trapped electrons and adiabatic passing electrons. The linear TEM growth rates are found to be damped by electron collisions. The effect of the ratio $T_{e}/T_{i}$ on the collisional damping is studied. The accuracy of the Lorentz model is tested against the full linearized operator predictions. The issue of $\rho^{*}$ effects in TEM simulations is addressed. A critical electron temperature gradient for linear TEM instabilities is established and compared to the temperature gradient dependence of the turbulence level in non-linear global simulations. Finally, the effects of the zonal flow shearing rate on TEM turbulence are investigated in both collisionless and collisional global ORB5 simulations. [Preview Abstract] |
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K1.00006: Electromagnetic Gyrokinetic Simulations of ITG Mode in Tokamak Plasmas. Ihor Holod Global gyrokinetic simulations of ion temperature gradient (ITG) mode and kinetic ballooning mode (KBM) are performed using GTC code with fluid-kinetic hybrid electron model, focusing on the plasma edge physics. Linear analysis of single and multiple toroidal mode number ITG is presented. Transition from ITG to KBM is observed with increasing $\beta _{e}$. Effect of kinetic electrons is investigated. [Preview Abstract] |
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K1.00007: Fast Chirping Event during Global Gyrokinetic Particle Simulations of the Toroidicity Induced Alfven Eigenmode Wenlu Zhang, Chenxi Zhang, Zhihong Lin Fast chirping event is observed in the nonlinear large scale gyrokinetic particle simulations for the toroidicity induced Alfven eigenmode (TAE) in the absence of external source and dissipation. It is found that the energetic particle drives the chirping through nonlinear kinetic effects while the nonlinear kinetic effect of thermal ions is the key to saturate the turbulence. Simulation result shows that the dynamical evolution of coherent structure in energetic particle phase space induces the TAE chirping. [Preview Abstract] |
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K1.00008: Self-Consistent Frequency Sweeping of TAE mode Ge Wang We have extended our intuitive Toroidal Alfven Wave (TAE) model [1] for describing spontaneous frequency sweeping by a destabilizing component of energetic particles. Now a fully developed self-consistent description for frequency sweeping of an isolated TAE mode has been developed. As in [1], we use the Rosenbluth, Berk,Van Dam tip theory [2], valid for low beta, large aspect ratio, circular tokamaks, to describe the evolution of the TAE wave equation. The wave is coupled to the particle dynamics that uses the Berk, Breizman, Ye map model [3] to construct the particle/wave Lagrangian associated with a phase space dependent mode structure. Then together with the appropriate Vlasov equation for describing the particle dynamics, a set of equations determining the dynamics of the system has been formulated. Adiabatic solutions have been obtained and work is underway in simulating the exact nonlinear dynamics. A status report of our results will be given at the meeting. \\[4pt] [1] G. Wang and H. L. Berk, Communication in Nonlinear Science and Numerical Simulation \textbf{17}, 2179 (2012) \\[0pt] [2] M. N. Rosenbluth,; H. L. Berk, J. Van Dam and D. M. Lingberg, Phys. Rev. Lett.~\textbf{68}, 596 (1992). \\[0pt] [3] Berk\textbf{,~}H.L.; Breizman, B.N.; Ye, H.\textit{~In:~}Physics of Fluids B~51993, 1506 (1993) [Preview Abstract] |
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K1.00009: Models for Alfv\'{e}n instabilities in stellarators Donald Spong Stellarators, helical RFPs and 3D tokamaks introduce symmetry-breaking effects that alter the structure of Alfv\'{e}n instabilities and their impact on energetic particle confinement. Loss of symmetry precludes an ignorable coordinate and requires taking into account both poloidal and toroidal couplings. New techniques for near term progress in 3D EP modeling have been developed, such as scalable algorithms (e.g., perturbative particle methods and windowed frequency solvers) and reduced-dimensionality models (e.g., gyro-Landau fluid). These methods have been developed for a range of 3D (tokamak/stellarator/RFP) configurations and have been compared with experimental measurements on LHD, TJ-II, HSX and RFX. Both modes with weak 3D couplings (TAE's in LHD) and strong 3D couplings (HAE's in TJ-II) will be discussed. Also, code-benchmarking activities have been started and will be described. In addition to their impact on fast ion confinement, the coherent frequencies of these AE modes (directly related to iota) can be useful markers for 3D equilibrium reconstruction. [Preview Abstract] |
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K1.00010: Kinetic Effects on Reversed Shear Alfv\'en Eigenmodes prior to ITB formation Nikolai Gorelenkov, Raffi Nazikian, Gerrit Kramer We consider one type of Alfv\'en Eigenmodes for a scenario of ITB formation when the safety factor minimum reaches its rational value. We develop a theory for the eigenmodes in this case sometimes known as either the bottom of the frequency sweep or the down sweeping Reversed Shear Alfv\'en Eigenmodes (RSAEs). The proper safety factor values for RSAE formation are achieved prior to ITB formation. First we show that, strictly speaking, the ideal MHD theory is not compatible with the eigenmode solution in the reversed shear plasma with $q_{min}$ above rational values. Corrected by a special, analytic FLR condition, MHD dispersion of these modes nevertheless can be developed. Numerically, MHD component of the structure can serve as a good approximation for the RSAEs. The large radial scale part of the analytic RSAE solution can be obtained from ideal MHD and expressed in terms of the Legendre functions analytically. The kinetic equation for the eigenmode structure with the FLR effects is solved numerically and agrees with the analytic solutions. Ideal MHD code NOVA is used to varify its applicability and compatibility with such plasmas. Kinetic properties of RSAEs can be important and trigger the ITB formation. [Preview Abstract] |
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K1.00011: Gyrokinetic particle simulations of reversed shear Alfv\'en eigenmodes in DIII-D tokamak Wenjun Deng Linear and nonlinear properties of reversed shear Alfv\'en eigenmodes (RSAEs) driven by density gradient of neutral beam injected fast ions in a well-diagnosed DIII-D experiment (discharge \#142111) are studied by simulations using the gyrokinetic toroidal code (GTC). Various RSAE damping mechanisms are identified and measured in the simulations, which shows that accurate damping and growth rate calculation requires true mode structure from non-perturbative, fully self-consistent simulation. The mode structure has no up-down symmetry mainly due to the radial symmetry breaking by the radial variation of fast ion density gradient, as measured in the experiment by electron cyclotron emission imaging. The RSAE frequency up-sweeping and the mode transition from RSAE to toroidal Alfv\'en eigenmode are in good agreement with the experimental results when scanning the values of the minimum safety factor $q_{\min}$ in simulations. Good agreements in frequencies, growth rates, and mode structures are obtained among simulations of gyrokinetic codes GTC and GYRO, and an MHD-hybrid code TAEFL. In the nonlinear stage, the RSAE saturates at the level of $\delta B / B_0 \sim 10^{-3}$, which qualitatively agrees with the experimental measurement. [Preview Abstract] |
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K1.00012: Gyrokinetic Particle Simulation of Alfven Eigenmodes with Zonal Fields Zhixuan Wang Effects of collective Shear Alfven wave instabilities on the energetic particle confinement in tokamak depend ultimately on the nonlinear evolution of the turbulence with spontaneously generated zonal fields (zonal flows and zonal currents). In this work, we study nonlinear interaction of Alfv\'en eigenmodes with zonal fields using global gyrokinetic toroidal code GTC. We choose to start from the simplest case, linear electrostatic eigenmodes in cylindrical geometry, and then gradually extend our study into electromagnetic eigenmode in toroidal geometry. We have verified GTC for linear simulation in cylindrical geometry with the $E\times B$ flow shear. Ion temperature gradient instability is observed to be suppressed when ExB flow shear is strong enough. A good agreement has also been achieved between our simulation result of kinetic Alfv\'en wave and LAPD experimental result. Now we are doing TAE (torodicity-induced Alfv\'en eigenmodes) simulation using the DIII-D equilibrium data. Linear simulation result agrees well with DIII-D data. Our next step is to include nonlinear effects to study the interaction between zonal fields and TAEs. Work supported by DOE SciDAC GSEP Center and Plasma Science Center. [Preview Abstract] |
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K1.00013: Gyrokinetic Simulation of Reverse Shear Alfven Eigenmodes in DIII-D Plasmas Yang Chen, Scott Parker, Guo-Yong Fu We present simulation results of the beam driven Reverse Shear Alfven Eigenmodes (RSAE) observed in DIII-D discharge 142111 using the Particle-in-Cell gyrokinetic code GEM [1]. Bulk ions and energetic particles are gyrokinetic, but electrons are described by a mass-less fluid model. Two schemes for obtaining the electric potential are implemented, one by solving the gyrokinetic Poisson equation for $\phi$ directly, the other by solving the gyrokinetic moment (GKM) equation for $\partial \phi/\partial t$ and then integrating in time. The GKM approach is found to be more robust for linear simulations (allowing larger time steps) but less robust for nonlinear simulations. Previous simulations reproduced the chirping in frequency as seen in the experiment. Recently it has been reported by other simulation codes (GTC, GYRO and TAEFL) that the shearing direction of the mode structure in the poloidal plane disagrees with observation. We found that the mode structure, including the shearing in the poloidal plane, is in general sensitive to the beam distribution. By changing the radial profile of the beam density while keeping the velocity dependence fixed, both shearing directions can be produced in the simulation. \\[4pt] [1] Y. Chen and S. E. Parker, J. Comp. Phys. 220, 839 (2007) [Preview Abstract] |
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K1.00014: Study of nonambipolar transport in perturbed tokamaks with a delta-f particle code Kimin Kim, Jong-Kyu Park, Gerrit J. Kramer, Allen H. Boozer Nonaxisymmetric magnetic perturbations can fundamentally change neoclassical transport in tokamaks, by distorting particle orbits on deformed or broken flux surfaces. This so-called nonambipolar transport is highly complex, and eventually a numerical simulation would be required to achieve its precise description and understanding. A new delta-f particle code has been developed for this purpose, using a modified pitch-angle collision operator preserving momentum conservation. The momentum conserving property, which is critical to separate nonaxisymmetic effects from axisymmetic effects in transport, was successfully tested in the axisymmetric case by demonstrating the annihilation of radial particle flux when driven only by like-particle collisions. In the nonaxisymmetic case, it is shown that a resonant perturbation significantly enhances particle flux as expected, but surprisingly that it can reduce bootstrap current. It is also found that nonresonant perturbations enhance both particle flux and bootstrap current, but their effects are generally weaker than a resonant perturbation. More detailed results will be presented and code upgrade plan to study Neoclassical Toroidal Viscosity (NTV) will be discussed. This work was supported by the US DOE Contract \#DE-AC02-09CH11466. [Preview Abstract] |
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K1.00015: Verification of Resistive Wall Mode Kinetic Stabilization Physics and Implications for Future Tokamaks J.W. Berkery, S.A. Sabbagh, R. Betti, J. Manickam It is important to understand and verify the physics of stabilization of the resistive wall mode (RWM) instability that can disrupt operation of future tokamaks. Recent theory and modeling has generally shown good agreement with experiment. This new understanding leads to different expectations of RWM stability in future devices. In particular, high or low rotation can stabilize the mode through resonance with particle motions, while intermediate rotation can yield RWM instability. Energetic particles have been shown to be generally stabilizing. Collisions both dissipate the mode energy and damp the stabilizing kinetic effects. Quantitative comparisons between experiment and theory are made using the MISK code. Theory alterations now focus on finding key changes that improve agreement, and the implications for future devices. One such alteration is the inclusion of anisotropic distribution functions, which changes the pressure-driven destabilization term. Present calculations show improved quantitative agreement with NSTX experimental marginal stability points, and that $\alpha$ particles will be required in ITER to maintain a stable RWM for expected plasma rotation profiles. Supported by U.S.~DOE contracts DE-FG02-99ER54524, DE-AC02-09CH11466, and DE-FG02-93ER54215. [Preview Abstract] |
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K1.00016: Kinetic MHD simulation of large $\Delta^{\prime}$ tearing mode Jianhua Cheng, Yang Chen, Scott Parker, Dmitri Uzdensky We have developed a second-order accurate semi-implicit $\delta \!f$ method for kinetic MHD simulation with Lorentz force ions and fluid electrons. The model has been used to study the resistive tearing mode instability, which involves multiple spatial scales. In small $\Delta^{\prime}$ cases, the linear growth rate and eigenmode structure are consistent with resistive MHD analysis. The Rutherford stage and saturation are demonstrated, but the simulation exhibits different saturation island widths compared with previous MHD simulations. In large $\Delta^{\prime}$ cases, nonlinear simulations show multiple islands forming, followed by the islands coalescing at later times. The competition between these two processes strongly influences the reconnection rates and eventually leads to a steady state reconnection. We will present various parameter studies and show that our hybrid results agree with fluid analysis in certain limits (e.g., relatively large resisitivities). [Preview Abstract] |
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K1.00017: Three-wave Coupling Model of the Hasegawa-Wakatani Turbulence Model Juhyung Kim, P.W. Terry We present a three-wave coupling analysis of the Hasegawa-Wakatani (HW) model with complex linear frequencies. A three-wave coupling model with complex linear frequencies based on a generalized one-field fluid model (such as Hasegawa-Mima) was analyzed with emphasis on the effect of the linear complex frequencies on the nonlinear frequency characteristics of each wavenumber. [1] The HW model consistently includes dynamically incoherent fluctuations, which were separately considered in the one-field model [1], and the phase relation between density and electrostatic fluctuations, which determines the level of the particle flux. In contrast to previous work with the HW model, it is shown numerically how the frequency spectrum and the phase relations in the steady state are dependent on the linear frequencies and linear growth rates. Theoretical implications of linearly unstable/stable modes on frequency spectra and the random-phase approximation in HW will be discussed. \\[4pt] [1] J.-H. Kim and P. W. Terry, Phys. Plasmas 18, 092308 (2011) [Preview Abstract] |
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K1.00018: A Delta-f to Full-F PIC Simulation Scheme for Tokamak Plasmas W.W. Lee, S. Ethier A generalized weight-based particle simulation schemes suitable for simulating microturbulence in magnetic fusion plasmas, where the zeroth-order inhomogeneity is important, has recently been developed [1]. The schemes is a generalization of the perturbative simulation schemes developed earlier for PIC simulations [2]. The new two-weight scheme, which can simulate both the perturbed distribution and the full distribution within the same code, has now been implemented to simulate tokamak plasmas using the GTC code [3]. Its development is based on the concept of multiscale expansion, which separates the scale lengths of the background inhomogeneity from those associated with the perturbed distributions. The code starts out as a delta-f code and gradually evolves into a full-F code, as such the delta-f part can help us with the noise issue in the linear stage and the full-F part can be useful in the fully nonlinear stage when the particle weights become too large or it becomes necessary to simulate realistic situations where sinks and sources become important.\\[4pt] [1] W. W. Lee, T. G. Jenkins and S. Ethier, Comp. Phys. Comm. 182, 564 (2011).\\[0pt] [2] S. E. Parker and W. W. Lee, Phys. Fluids B 5, 77 (1993).\\[0pt] [3] Z. Lin, T. S. Hahm, W. W. Lee, W. M. Tang and R. White, Science 281, 1835 (1998). [Preview Abstract] |
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K1.00019: Implementation of 2D domain decomposition in the UCAN gyrokinetic PIC code for non-diffusive transport studies in tokamaks Jean-Noel Leboeuf, Viktor Decyk, David Newman, Raul Sanchez The massively parallel, nonlinear, 3D, toroidal, electrostatic, gyrokinetic, PIC, Cartesian geometry UCAN code, with particle ions and adiabatic electrons, has been successfully exercised to identify non-diffusive transport characteristics in DIII-D-like tokamak discharges. The limitation in applying UCAN to larger scale discharges is the 1D domain decomposition in the toroidal (or z-) direction for massively parallel implementation using MPI which has restricted the calculations to a few hundred ion Larmor radii per minor radius. To exceed these sizes, we have implemented 2D domain decomposition in UCAN with the addition of the y-direction to the processor mix. This has been facilitated by use of relevant components in the 2D domain decomposed PLIB2 library of field and particle management routines developed for UCLA's UPIC framework of conventional PIC codes. The gyro-averaging in gyrokinetic codes has necessitated the use of replicated arrays for efficient charge accumulation and particle push. The 2D domain-decomposed UCAN2 code reproduces the original 1D domain results within roundoff. Production calculations at large system sizes have been performed with UCAN2 on 131072 processors of the Cray XE6 at NERSC. [Preview Abstract] |
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K1.00020: On the interpretation of particle tagging data Fred Skiff We develop a formalism for the interpretation of optical tagging data obtained from laser-induced fluorescence (LIF) experiments. There are three basic components to the calculation. The first is the modification, due to optical pumping, of the state-density velocity distribution function. The central part is the calculation of the two-point conditional probability function for ion orbits in the (phase-space) vicinity of a central guide orbit that contributes to the signal. The final part is the calculation of the modified LIF signal of the search laser due to the test-particle distribution function. As a special case we consider the model of a steady, uniform plasma in a straight magnetic field under the assumption of a constant (Lenard-Bernstein) velocity-space diffusion coefficient. In this case there is no need of the guide-orbit expansion in order to evaluate 12 of the thirteen integrals involved analytically. These twelve integrals cover the instrumental selection of initial and final phase-space coordinates of the test-particles. The remaining integral over time must be performed numerically and can be used to evaluate the test-particle transfer function in either the time or frequency domains (the latter being appropriate for experiments involving ``chopped'' lasers). The effect of finite quantum state lifetime (due, for example, to collisional quenching in the case of metastable states) is included. [Preview Abstract] |
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K1.00021: Impurity Modes and Signature of the I-Regime Tianchun Zhou, Bruno Coppi The excitation of an impurity mode [1, 2] at the plasma edge is considered as the signature of the I-Regime [3]. The mode phase velocity, predicted in the electron diamagnetic velocity direction, was confirmed by the experiments [4]. The outward impurity transport produced by this mode is consistent with the observation that impurities accumulate at the edge in the I-Regime, a feature not present in the EDA or Elmy H-Regime. The plasma spontaneous rotation in the ion diamagnetic velocity direction is also consistent with the mode phase velocity direction, according to the Accretion Theory[5] of this phenomenon. In accordance with our theory, the I-Regime exhibits a temperature ``knee'' at the edge but no density ``knee'' as the mode excitation involves large values of $d\ln T_i/d\ln n_i$. A correlation of the values of the observed poloidal magnetic field fluctuations with those of the derived density fluctuations is provided by the same theory.\\[4pt] [1] B. Coppi, et al., Phys. Rev. Lett. {\bf 17}, 377 (1966).\\[0pt] [2] B. Coppi and T. Zhou, Phys. Lett. A {\bf 375}, 2916 (2011); PoP {\bf 18} (2011)(in press) and MIT-LNS Report HEP 09/04 (2009).\\[0pt] [3] A. Hubbard, et al., PoP {\bf 18}, 056115 (2011).\\[0pt] [4] I. Cziegler(2010).[5]B. Coppi, Nucl. Fusion {\bf 42}, 1 (2002). [Preview Abstract] |
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K1.00022: 3-D Particle-in-cell simulations of the sawtooth crash J.F. Drake, Michael Swisdak The results of 3-D particle-in-cell simulations of reconnection in system with an ambient pressure gradient are presented that explore whether drift-wave turbulence can facilitate energy loss from the core of tokamaks during the sawtooth crash. During reconnection leading to the sawtooth crash, the ambient pressure gradient across the magnetic x-line becomes very steep as hot plasma from the core convects into the colder q=1 surface. Gradients scale lengths of the order of the ion sound Larmor radius develop in 2-D simulations. The dominant instabilities in such sharp gradients are associated with drift waves rather than ballooning modes. In 3-D simulations we are exploring the development of the steep gradients in the vicinity of the x-line and magnetic separatrices as reconnection develops, the range of unstable drift waves that are driven unstable as the local pressure gradient increases and their role in facilitating the expulsion of the hot plasma core during the crash. [Preview Abstract] |
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K1.00023: Advances in Neoclassical Theory of Poloidal and Toroidal Rotation in Tokamaks Cheonho Bae, Weston Stacey, Wayne Solomon Rotation of tokamak plasmas is of intrinsic interest and also important for stabilization of MHD instabilities. Neoclassical rotation theory and gyroviscosity both depend on the poloidal dependence of the magnetic flux surface geometry. Gyroviscosity in the circular flux surface formulation [1] was found to lead to over-prediction of toroidal rotation velocities in DIII-D by a factor of about 2. We now represent neoclassical plasma rotation theory in the more accurate ``Miller equilibrium'' flux surface geometry [2] for comparison with DIII-D discharges. The advanced rotation theory with the Miller model takes into account Shafranov shift, elongation, and triangularity of flux surfaces. Development of the neoclassical plasma rotation theory for both the circular and Miller equilibrium models is complete and will be presented. Initial comparisons of the improved circular model rotation calculation with experiment show improved agreement with experiment. Additional calculations based on the Miller equilibrium model are in progress. \\[4pt] [1] W.M. Stacey, et al., Phys. Plasma \textbf{13}, 062508 (2006).\\[0pt] [2] R.L. Miller, et al., Phys. Plasmas \textbf{5}, 973 (1998). [Preview Abstract] |
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K1.00024: Transonic Flow in a Tokamak Eliezer Hameiri, Luca Guazzotto Observed poloidal flow in tokamaks is of the order of the sound speed, multiplied by the ratio of poloidal/total magnetic field (the poloidal sound speed). At this range, the governing Grad-Shafranov (GS) equation changes its type twice: From elliptic near the center (low velocity) to hyperbolic in the region where the velocity is near the poloidal sound speed, then again to elliptic when the velocity is higher still. Previous work established the existence of a contact discontinuity across which the plasma density falls and the Mach Number increases. One problem with this is that the computation solves the GS equation as if it is elliptic. Moreover, a hyperbolic region never shows up, presumably because it is extremely narrow. These facts cast some doubt on the previous results. Here we consider this matter analytically. First, we construct a model problem having similar transitions of type as the transonic plasma equation. The model problem is solved analytically and indeed shows a hyperbolic region, as expected. Second, we treat the exact GS equation asymptotically, the small parameter being the ratio of sound to Alfven speed, which corresponds to the width of the hyperbolic region. We show that as this becomes very small, the hyperbolic region shrinks to naught, leaving no trace left over, so that solving the GS equation as an elliptic problem with a contact discontinuity yields the correct asymptotic approximation to the solution, thus validating the work of Ref. 1.\\[4pt] [1] L. Guazzotto, R. Betti, J. Manickam and S. Kaye, Phys. Plasmas 11, 604 (2004) [Preview Abstract] |
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K1.00025: Two-Fluid Equilibrium for Transonic Poloidal Flows Luca Guazzotto, Riccardo Betti Much analytical and numerical work has been done in the past on ideal MHD equilibrium in the presence of macroscopic flow. In recent years, several authors have worked on equilibrium formulations for a two-fluid system, in which inertial ions and massless electrons are treated as distinct fluids. In this work, we present our approach to the formulation of the two-fluid equilibrium problem. Particular attention is given to the relation between the two-fluid equations and the equilibrium equations for the single-fluid ideal MHD system. Our purpose is to reconsider the results of one-fluid calculation with the more accurate two-fluid model, referring in particular to the so-called transonic discontinuities, which occur when the poloidal velocity spans a range crossing the poloidal sound speed (i.e., the sound speed reduced by a factor $B_p/B$). It is expected that the one-fluid discontinuity will be resolved into a sharp gradient region by the two-fluid model. Also, contrary to the ideal MHD case, in the two-fluid model the equations governing the equilibrium are elliptic in the whole range of interest for transonic equilibria. The numerical solution of the two-fluid system of equations is going to be based on a code built on the structure of the existing ideal-MHD code FLOW. [Preview Abstract] |
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K1.00026: On the stability of MHD equilibria with flow Tommaso Andreussi, Philip J. Morrison, Francesco Pegoraro Three kinds of energy principles arising from the Hamiltonian structure of the (MHD) equations are used to determine sufficient stability conditions. The Lagrangian energy principle of Ref.[1] is presented and the stability conditions for symmetric and non-symmetric perturbations are introduced. Exploiting the noncanonical Hamiltonian formulation of MHD [2] plasma flows are analyzed in terms of Eulerian variables. An energy principle in Eulerian form is deduced for equilibria with a geometric symmetry and sufficient conditions for stability are obtained by expanding a functional F composed of the sum of the Eulerian energy plus Casimir invariants to second order. Next, an energy principle based on dynamically accessible variations [3] that preserve the invariants of the system explicitly is considered. Dynamically accessible variations do not rely on any symmetry and thus give general criteria for stability. Finally, the conditions obtained from the three different approaches are compared and implications about nonlinear stability are discussed.\\[4pt] [1] E.A. Frieman and M. Rotenberg, Rev. Mod. Phys., 32 898 (1960).\\[0pt] [2] P.J. Morrison and J.M.~Greene, Phys. Rev. Lett., 45 790 (1980).\\[0pt] [3] P.J. Morrison, Rev. Mod. Phys., 70 467 (1998). [Preview Abstract] |
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K1.00027: Resistive wall boundary conditions on nonlinear MHD simulations in toroidal geometry A.L. Montgomery, C.C. Hegna, C.R. Sovinec, S.E. Kruger The resistive wall present in tokamaks is important for both unstable modes and feedback control. The case of a periodic cylinder with a resistive wall and external resonant magnetic perturbations was studied using the Nimrod code. This boundary condition is now being generalized to toroidal geometry. The magnetic fields inside the domain are matched with external fields found using a vacuum-field solver. The toroidal boundary condition is tested in the large aspect ratio, circular cross-section limit, and compared to the results from the periodic cylinder boundary condition. The mechanics of the addition of external resonant magnetic perturbations to the toroidal boundary condition will be discussed. [Preview Abstract] |
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K1.00028: ECCD-induced tearing mode stabilization in coupled IPS/NIMROD/GENRAY HPC simulations Thomas Jenkins, S.E. Kruger, E.D. Held, R.W. Harvey, W.R. Elwasif We summarize ongoing developments toward an integrated, predictive model for determining optimal ECCD-based NTM stabilization strategies in ITER. We demonstrate the capability of the SWIM Project's Integrated Plasma Simulator (IPS) framework to choreograph multiple executions of, and data exchanges between, physics codes modeling various spatiotemporal scales of this coupled RF/MHD problem on several thousand HPC processors. As NIMROD evolves fluid equations to model bulk plasma behavior, self-consistent propagation/deposition of RF power in the ensuing plasma profiles is calculated by GENRAY. Data from both codes is then processed by computational geometry packages to construct the RF-induced quasilinear diffusion tensor; moments of this tensor (entering as additional terms in NIMROD's fluid equations due to the disparity in RF/MHD spatiotemporal scales) influence the dynamics of current, momentum, and energy evolution as well as the MHD closures. Initial results are shown to correctly capture the physics of magnetic island stabilization; we also discuss the development of a numerical plasma control system for active feedback stabilization of tearing modes. [Preview Abstract] |
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K1.00029: Simulations of current-filament dynamics and relaxation in the Pegasus ST J.B. O'Bryan, C.R. Sovinec Nonlinear numerical computation is used to investigate the relaxation of non-axisymmetric current channels from washer-gun plasma sources into ``tokamak-like" plasmas in the Pegasus Toroidal Experiment. Resistive MHD simulations with the NIMROD code utilize ohmic heating, temperature-dependent resistivity, and anisotropic, temperature-dependent thermal conduction corrected for regions of low magnetization [Braginskii 1965] to reproduce critical transport effects. A strong reversed current sheet suggests magnetic reconnection between adjacent passes of the current channel. Axisymmetric current rings are periodically released from the channel when adjacent passes come into contact. After large-scale magnetic field reversal, a hollow current profile is observed with significant poloidal flux amplification having accumulated over many reconnection cycles. [Preview Abstract] |
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K1.00030: Control of ideal and resistive magnetohydrodynamic instabilities in reversed field pinches with 2 resistive walls by sensing three components of B Karl Sassenberg, Andrew S. Richardson, Dylan P. Brennan, John M. Finn Confinement times of fusion plasmas can be greatly enhanced through access to flexible and reliable control of both resistive and ideal plasma modes. Numerical studies are presented of magnetohydrodynamic instability control through sensing and proportional feedback in Reversed Field Pinches (RFPs) with two resistive walls. The feedback signal incorporates all three components of the magnetic field perturbation, each with its own gain factor. This study extends the work of Richardson \& Finn (Phys. Plasmas vol. 17, p. 112511 (2010)) and includes an important feature of the RFX-mod experiment, namely two resistive walls with external measurements. In particular, when a single resistive wall scenario is considered, feedback based on sensing the first tangential component (the derivative of the helical flux) inside the wall is found to perform better than when the same component is measured outside the wall. Furthermore, the effect of feedback control on the magnetosonic (MS) mode with two walls is compared to the single resistive wall scenario with the first tangential component measured outside. In the latter case feedback of the second tangential component (the helical field) was found to drive the MS mode unstable. [Preview Abstract] |
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K1.00031: Flow profile relaxation in two-fluid RFP modeling C.R. Sovinec, J.P. Sauppe, J.R. King Relaxation theories based on two-fluid modeling predict inherent coupling between changes in magnetic field and plasma flow profiles [1]. Rutherford scattering measurements of majority ion flow suggest that this effect may be realized during sawtooth relaxation events in MST [2], when flow parallel to the magnetic field increases in the core and decreases in the edge. To investigate FLR effects on RFP relaxation, we use the NIMROD code to evolve 3D fluctuations consistently with profile evolution. Our previous two-fluid computations with warm-ion effects show relaxation-induced changes in parallel flows that are directionally consistent with the experimental result with respect to the magnetic-field orientation [3]. However, MST is run with opposite magnetic helicity, which is relevant for dynamo. Here, we investigate the influence of background flow profiles, which are present in MST but not in our previous computations. Computational diagnostics of Hall dynamo, fluctuation-induced Reynolds stress, and gyroviscous forces are used to assess forces that affect the mean flow in the simulated results.\\[4pt] [1] For example, C. C. Hegna, PoP 5, 2257 (1998).\\[0pt] [2] A. Kuritsyn, et. al., PoP 16, 55903 (2009).\\[0pt] [3] J. R. King, BAPS 56, No. 16, JI2 4 and PoP submitted (2011). [Preview Abstract] |
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K1.00032: Asymptotic expansion for stellarator equilibria with a non-planar magnetic axis: Numerical progress Antoine Cerfon, Jeffrey Freidberg, Felix Parra We have recently presented a new asymptotic analysis [1], which reduces the complexity of the MHD equilibrium equations in stellarators and generalizes the asymptotic approach followed by Greene and Johnson in their classic paper [2]. As in [2], our expansion relies on the small ratio of the helical magnetic field to the vacuum toroidal field. However, our ordering relaxes the Greene and Johnson constraint which assumes a strong separation in length scales between the helical period and the major radius. In our expansion these two length scales are of comparable order, which provides a better match with modern stellarator experiments. Toroidal effects enter the analysis in the same order as helical effects, allowing the calculations of equilibria with multiple helicities and a non-planar magnetic axis. The end result of our analysis is a set of two coupled PDEs for the plasma pressure and the magnetic vector potential, which fully determine the stellarator equilibrium. We present simple analytic solutions to these equations, and discuss the numerical methods we are developping to calculate more general stellarator equilibria.\\[4pt] [1] A.J. Cerfon, J.P. Freidberg, and F.I. Parra, Bull. Am. Phys. Soc. 56, 16 GP9.00081\\[0pt] [2] J.M. Greene and J.L. Johnson, Phys. Fluids 4, 875 (1961) [Preview Abstract] |
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K1.00033: Stability analysis and non-field-periodic islands with the SIESTA code C.R. Cook, S.P. Hirshman, R. Sanchez, D.T. Anderson SIESTA is a three-dimensional magnetohydrodynamic equilibrium code capable of resolving magnetic islands in toroidal plasma confinement devices. The simulation begins with a VMEC equilibrium containing closed, nested magnetic flux surfaces. In general, this equilibrium can be unstable to tearing modes as VMEC is purely an ideal MHD code. SIESTA then calculates a new equilibrium by perturbing the initial configuration and following a nonlinear energy minimization process with finite resistivity. The converged SIESTA equilibrium with islands will then be stable. The Solov'ev tokamak equilibrium is a configuration that is tractable analytically. A stability analysis will be performed on an unstable VMEC Solov'ev equilibrium as well as a stable, converged SIESTA Solov'ev equilibrium. These numerical results for the MHD eigenspectrum will be compared to what is expected from theory. Presently SIESTA assumes that plasma perturbations, and thus also magnetic islands, are field-periodic. This limitation is being removed from the code by allowing the displacement toroidal mode number to not be restricted to multiples of the number of field periods. An example of a non-field-periodic perturbation in CTH will be discussed. [Preview Abstract] |
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K1.00034: Analytical and Numerical Study of Lower Hybrid Wave Propagation in Plasma Alessandro Cardinali, Valeria Fusco Lower hybrid current drive (LHCD) is an effective technique for non-inductively sustaining and for current profile modification of tokamak plasmas. Experiments have indicated that the bootstrap current alone is not sufficient to develop and sustain advanced scenario for reactor relevant experiments like ITER and DEMO, and LHCD may be particularly well suited for efficiently driving current off-axis ($r/a > 0.8$) in reactor grade plasmas. In order to study the plasma-wave interaction, an equations system has been derived from the Vlasov-Maxwell model, with the help of appropriate simplifying hypothesis. The solution can be obtained not only by considering the full wave equation but also by using methods based on asymptotic techniques like the WKB. While the full wave solution is a knotty problem both numerically and analytically, due to the 3D involved in the tokamak geometry, the asymptotic technique based on the WKB approximation leads to an amazing simplification, reducing the problem to an integration of a system of ordinary differential equations (ray tracing) for both the phase integral and the amplitude of the electric field. Particular care is requested in the solution of the wave equation when dealing with singular points like cut-offs and mode-conversion, which are easily met at the plasma periphery. To test the reliability of the aforesaid methods, a strict comparison between the full wave solution and the WKB approximation is performed in a paradigmatic situation (1D cylindrical geometry). [Preview Abstract] |
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K1.00035: Vlasov Simulations of Electron Plasma Waves: self-focusing and modulational instability Richard Berger, J. Banks, S. Brunner, B. Cohen, J. Hittinger, W. Rozmus, D. Strozzi, B. Winjum Vlasov simulations of nonlinear electron plasma (EPW) waves are presented in 2D (2 space and 2 velocity dimensions) with LOKI (Banks et al, Phys. Plasmas 18, 052102 (2011)). EPWs are created with an external traveling wave potential with a transverse envelope of width $\Delta y$ such that thermal electrons transit the wave in a ``sideloss'' time, $t_{sl} \sim \Delta y/v_e$ where $v_e$ is the electron thermal velocity. The plasma wave field envelope and associated self-consistent quasi-steady distribution of trapped electrons are studied after the external drive is turned off. For sufficiently short times and large enough wave amplitudes, the magnitude of the negative frequency shift from trapped electrons is a local function of electrostatic potential and the phase of the wave on axis lags the off axis phase. Analysis and simulations are presented of the damping and trapped-electron-induced self-focusing (H. Rose, Phys. Plasmas 12, 012318 (2005)) of the finite-amplitude EPW. The onset of trapped electron modulational instability (S. Brunner and E. Valeo, PRL 93, 145003 (2004)) both along and transverse to the direction of propagation is studied as a function of the wave amplitude and the system length. [Preview Abstract] |
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K1.00036: An Analysis of Lower Hybrid Grill Coupling Using an Efficient Full Wave Code Josef Preinhaelter, Jakub Urban, Linda Vahala, George Vahala Lower hybrid (LH) waves are very important for heating and current drive in tokamaks. A code is developed for 3D grills and the problem of efficient coupling: the power density spectrum, the power reflection coefficient, the power lost by the waves launched in the inaccessible region and the directivity of the waves. An efficient adaptive full wave solver is used to determine the wave propagation in a 1D plasma slab geometry. The very large number of 2D k-space infinite integrals for the coupling elements are solved using high order Gaussian quadratures combined with 2D B-splines in the accessible region. The code can handle large structures and many modes because the computational time is only weakly dependent on the size of the problem. An iterative evaluation of the integrands in the inaccessible region solves the currently overlooked near singular behavior of the integrands as well as the spectral power density associated with the eigenmodes. The role of collisions is clarified. We determine the 3D electric field in front of the grill and consider several COMPASS grills operating either at 1.3 GHz or 3.7 GHz with various waveguide phasing. [Preview Abstract] |
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K1.00037: Scattering of radio frequency waves by edge density blobs in tokamaks A.K. Ram, K. Hizanidis, Y. Kominis The density blobs and fluctuations present in the edge region of magnetic fusion devices can scatter radio frequency (RF) waves through refraction and diffraction. A previous study has considered refractive scattering using the geometric optics approximation [1]. It is found that the scattering can diffuse rays in configuration space and in wave-vector space. The diffusion in space can make the rays miss their intended target region, while the diffusion in wave-vector space can broaden the wave spectrum and modify the wave damping profile. The geometric optics approximation is of limited validity. We have developed a full-wave, cold plasma, model for wave scattering in which the size and density of the blobs are arbitrary. The model allows for diffractive scattering of waves as well as coupling of the incident wave to other plasma waves. Diffractive scattering can lead to ``shadowing'' while the coupling to other plasma waves can broaden the spectrum of the incident wave, and reduce the power propagating into the interior of the plasma. The full-wave model and the consequences of diffractive scattering of RF waves by blobs will be discussed. \\[4pt] [1] K. Hizanidis, A.K. Ram, Y. Kominis, and C. Tsironis, {\it Phys. Plasmas} {\bf 17}, 022505 (2010). [Preview Abstract] |
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K1.00038: Electron Temperature Fluctuations Associated with the Weakly Coherent Mode in the Edge of I-mode Plasmas A.E. White, P. Phillips, D.G. Whyte, A.E. Hubbard, C. Sung, J.W. Hughes, A. Dominguez, J. Terry, I. Cziegler New measurements of electron temperature fluctuations associated with the weakly coherent mode (WCM) during improved mode, or I-mode plasmas at Alcator C-Mod are presented in this poster [A. E. White, et al. Nuclear Fusion, 51, 113005 (2011)]. The measurements are made with a 32-channel, high-resolution profile ECE radiometer. The WCM electron temperature fluctuations are localized to a 1 cm region inside the last closed flux surface. The WCM electron temperature fluctuation level is measured in several different I-mode discharges and is in the range 1-2\%, which is up to an order of magnitude smaller than the WCM density fluctuation level. The WCM edge fluctuations observed in I-mode are believed to play a role in increasing particle transport but not energy transport in the edge of I-mode plasmas. The large difference between normalized density and electron temperature fluctuation amplitudes provides new evidence that the WCM fluctuations can separately affect energy and particle transport. [Preview Abstract] |
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K1.00039: Effect of 3-D field perturbations on kinetic ballooning mode stability C.C. Hegna, T.M. Bird Applied resonant magnetic field perturbations can alter the plasma transport properties through three-dimensional modulations of plasma shaping parameters. This mechanism is viable even in the presence of shielding by plasma rotation. Using local 3-D equilibrium theory, shaped tokamak equilibria altered by small ($\delta B/B_0 \sim 10^{-3}-10^{-4}$) 3-D distortions can be constructed. The ideal MHD ballooning mode stability limit is lowered in the presence of the 3-D field relative to the axisymmetric case due to 3-D modulations of the local magnetic shear [1]. In particular, Pfirsch-Schl\"uter currents driven by 3-D distortions of the geodesic curvature are produced that alter the local magnetic shear. These currents become large as the field pitch of the magnetic field line approaches a rational value. Since ideal MHD ballooning stability calculations are sometimes used as a proxy for kinetic ballooning mode onset, these calculations suggest 3-D flux surface distortion of sufficient magnitude can affect anomalous transport. In this work, analysis of the kinetic ballooning eigenmode equation is performed that accounts for the role of the 3-D equilibrium distortion.\\[4pt] [1] T. M. Bird and C. C. Hegna submitted to \emph{Phys. Rev. Lett.} (2012). [Preview Abstract] |
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K1.00040: Free boundary ballooning mode representation Linjin Zheng Considerable efforts have been made in this field to develop a free boundary ballooning mode representation, which can incorporate the peeling mode stability criterion. Those efforts have not succeeded, simply because the so-called ballooning mode invariance is broken toward plasma edge. This makes 1D description of high n modes at plasma edge become impossible, where $n$ is toroidal mode number. Nevertheless, we prove that the existence of ``half" ballooning mode invariance toward plasma core enables an $1.\delta$-dimentional representation of the modes, where $\delta \sim {\cal O}(1/n)$. This considerably reduces the complicity in investigating high n modes at plasma edge and can be used to study peeling-ballooning modes. This technique can also be useful to extend the 1D calculation of fixed boundary ballooning modes for free boundary ballooning modes. Numerical example will also be presented together with the topological symmetry analysis. [Preview Abstract] |
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K1.00041: Magnetic-perturbation-induced plasma transport in H-mode pedestals J.D. Callen, A.J. Cole, C.C. Hegna Plasma toroidal rotation can prevent reconnection of externally applied resonant magnetic perturbation (RMP) fields on rational surfaces and hence magnetic island formation and stochasticity in the edge of tokamak H-mode plasmas. However, magnetic flutter induced by RMPs off the rational surfaces causes a radial electron heat diffusivity $\chi_e^{RMP}\sim (\delta B_r/B_0)^2\chi_\| F(x)$ in which $\chi_\|\sim v_{Te}^2/\nu_e$ is an effective parallel electron heat diffusivity and $F$ is a spatially varying factor [1]. The flutter also diffuses electrons radially and causes a factor of about 3 smaller increases in density diffusion. Since the electron density transport is non-ambipolar, this flutter process also modifies the radial electric field and plasma toroidal rotation. This work extends the previously developed periodic cylinder screw pinch model [1] of RMP-flutter-induced plasma transport to a full toroidal model which is axisymmetric to lowest order plus gyroradius-small magnetic field perturbations. The possible role of the RMP-flutter-induced plasma transport in reducing pressure gradients in H-mode pedestals and thereby suppressing ELMs will be discussed.\\[4pt] [1] J.D.\ Callen et al., UW-CPTC 11-13, http://www.cptc.wisc.edu (submitted to Nucl.\ Fusion.) [Preview Abstract] |
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K1.00042: Global two-fluid simulation of tokamak Scrape-Off-Layer turbulence Annamaria Mosetto, Federico David Halpern, Sebastien Jolliet, Paolo Ricci We present non-linear self-consistent 3D global fluid simulations of the SOL plasma dynamics using the Global Braginskii Solver (GBS) code. The code solves the drift-reduced Braginkii equations in a collisional plasma, with cold ions. The GBS code, originally developed for an electrostatic, 2D configuration has been recently upgraded to describe the SOL turbulence with the introduction of the variable curvature along the magnetic field lines, the magnetic shear, and the electromagnetic effects. The code peculiarity lies in the capability of evolving self-consistently equilibrium and 3D fluctuations as a results of the interplay among the sources, the turbulent transport and the plasma losses at the limiter plates. The non-linear simulations have been interpreted by means of linear analysis of the fluid equations modeling the system. This points out the presence of two main instabilities driving turbulence: the Drift Wave and the Resistive Balloning instabilities. The dependence of the instabilities growth rate and of their properties on the physical parameters of the system, for example the characteristic length of the plasma density, the magnetic shear and the $\beta$ ratio have been explained and the regions where each instability dominates have been identified. [Preview Abstract] |
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K1.00043: Wave-particle interaction in parallel transport of long mean-free-path plasmas along open field magnetic field lines Zehua Guo, Xianzhu Tang A tokamak fusion reactor dumps a large amount of heat and particle flux to the divertor through the scrape-off plasma (SOL). Situation exists either by necessity or through deliberate design that the SOL plasma attains long mean-free-path along large segments of the open field lines. The rapid parallel streaming of electrons requires a large parallel electric field to maintain ambipolarity. The confining effect of the parallel electric field on electrons leads to a trap/passing boundary in the velocity space for electrons. In the normal situation where the upstream electron source populates both the trapped and passing region, a mechanism must exist to produce a flux across the electron trap/passing boundary. In a short mean-free-path plasma, this is provided by collisions. For long mean-free-path plasmas, wave-particle interaction is the primary candidate for detrapping the electrons. Here we present simulation results and a theoretical analysis using a model distribution function of trapped electrons. The dominating electromagnetic plasma instability and the associated collisionless scattering, that produces both particle and energy fluxes across the electron trap/passing boundary in velocity space, are discussed. [Preview Abstract] |
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K1.00044: Interpretation of DIII-D Edge Pedestal Experiments John-Patrick Floyd II, Min-Hee Sayer, Weston Stacey The presence of a large pinch velocity in the edge pedestal of high confinement (H-mode) tokamak plasma discharges is important in edge transport, and must be included in theoretical modeling of experiments. The pinch-diffusion relation [1] describing edge transport has been derived from first principles and includes a momentum-balance satisfying pinch term. This pinch-diffusion relation is used to analyze and study edge pedestal transport in two scenarios important to ongoing plasma physics research: i) the L-H mode transition, and ii) the evolution of edge pedestal structure and dynamics between ELM disruptions. In the study of the L-H mode transition, the pinch-diffusion relation is used to compute electron densities at several points near the L-H transition. These results are examined to learn more about factors affecting transport near the transition. This should result in improved insight into edge pedestal transport factors that play a role in triggering the L-H transition. The study of inter-ELM edge transport and edge pedestal structure evolution is done by taking composite data during an H-mode shot, and using the cylindrical, time-dependent pinch-diffusion relation to model transport across the inter-ELM period. We will further analyze the evolution of pedestal transport between ELMs, and by observing properties immediately after an ELM, we can gain insight of the change in edge pedestal parameters before and after ELMs. \\[4pt] [1] Stacey, W. M. 2004, Phys. Plasmas, 11, 5487. [Preview Abstract] |
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K1.00045: Gyrokinetic particle simulation of linear instabilities in DIII-D pedestal plasmas Daniel Fulton, Zhihong Lin, Xueqiao Xu Understanding the physics in the pedestal region of toroidal plasmas is critical to obtaining confinement with high core temperatures. The pedestal region is characterized by large gradients in pressure, temperature, and density profiles, which provide a source of free energy to drive a number of instabilities, such as ion and electron temperature gradient modes, kinetic ballooning mode, and trapped electron modes. Studying these instabilities can provide information on the limits of allowable gradients in the pedestal. In this study, we explore linear instabilities in the pedestal region of DIII-D discharge 131997 using the gyrokinetic toroidal code (GTC) and compare GTC simulation results with other gyrokinetic codes. [Preview Abstract] |
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K1.00046: Fast Non-Fourier Methods for Landau-Fluid Operators A.M. Dimits, I. Joseph, M.V. Umansky Landau-fluid (including gyro-Landau-fluid) equations use closure terms that involve nonlocal operators. When the background plasma has significant inhomogeneities, or sometimes because of particular code design or boundary conditions, it is desirable to compute the closure terms in configuration space. The nonlocality of Landau-fluid operators makes the na\"ive direct computation of the closure terms in configuration space via convolution or matrix multiplication expensive. We have developed a fast non-Fourier method for the computation of Landau-fluid closure terms based on an accurate and tunable approximation that can be numerically implemented through the solution of matrix equations in which the matrices are tridiagonal or narrowly banded. The accuracy and fast computational scaling of the method are demonstrated. The accuracy is quantified, both semi-analytically for the operator itself and for the resulting plasma response function, as well as for the results of the numerical implementation of the method. A spectral colocation analysis has been developed that greatly aids in the optimization of the approximations for accuracy and computational cost, both for cases that are collisionless and for cases where collisional and collisionless damping processes compete. [Preview Abstract] |
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K1.00047: A 3-field electromagnetic gyro-fluid model for tokamak edge turbulence P.W. Xi, X.Q. Xu To investigate the L-H transition of low-high confinement mode, the H-mode pedestal structure and edge-localized modes, a set of 3-field gyro-fluid equations is derived based on an electromagnetic gyro-fluid model. By evolving gyrokinetic vorticity density, ion density and Ohm's law, this set of gyro-fluid equations correctly describes a range of plasma instabilities relevant to edge plasmas, such as low to intermediate n peeling-ballooning mode and high-n drift ballooning mode. Meanwhile electron acoustic wave is also taken into account. Utilizing Pad\'{e} approximation for modified Bessel function, this set of equations is implemented under BOUT++ framework with full ion gyro-radius effects and the simulation results are compared with previous two-fluid model with ion diamagnetic drift, which retains the first-order finite ion gyro-radius correction. This simple 3-field gyro-fluid model does not take Landau damping into account. Linear simulations show a consistent diamagnetic stabilization with two-fluid model and reveal several new features at high-n modes due to kinetic effects and nonlinear simulations demonstrate the importance of kinetic effects on ELM crash as well as turbulent transport in H-mode recovery phase. A more comprehensive gyro-fluid model is also developed by using the gyrokinetic equations for edge plasmas. [Preview Abstract] |
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K1.00048: A generalized energy principle for a magnetorotational instability model Emanuele Tassi, Phil Morrison, Natalia Tronko We study the equilibria of the Magnetorotational Instability system by using the noncanonical Hamiltonian approach [1], since it provides variational principles for equilibria that can be used to assess stability. We show that a reduced system of equations derived in [2] is an infinite-dimensional noncanonical Hamiltonian system. The noncanonical Poisson bracket is identified and shown to obey the Jacobi identity, and families of Casimir invariants are obtained. Explicit sufficient conditions for the energy stability of two classes of equilibria are identified by means of the Energy-Casimir method. Comparison between the stability conditions obtained in the two cases indicates that the presence of an equilibirum magnetic field along the direction of the ignorable coordinate does not introduce destabilizing effects. An analogy is found and physically interpreted between terms of the MRI perturbation energy and terms appearing in the energy principle stability analysis of CRMHD for tokamaks [3].\\[4pt] [1] P.~J.~Morrison, Rev.~Mod.~Phys., ${\bf 70}$, 467 (1998).\\[0pt] [2] K.~Julien and E.~Knobloch, Phil. Trans.\ Roy.\ Soc., {\bf 386A},1607 (2010).\\[0pt] [3] R.D. Hazeltine, et. al, Phys.~Fluids {\bf 28}, 2466 (1985). [Preview Abstract] |
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K1.00049: Fields and Plasma Structures Around ``Shining'' Black Holes: Solitary Rings and Tri-dimensional Topologies B. Coppi Field and plasma configurations that can be the distinguishing feature of and surround ``shining'' black holes have been identified. Considering the observation of the Quasi Periodic Oscillations that can be associated with inhomogeneous rotating plasmas, tri-dimensional rotating configurations have been looked for and found under special conditions. One is that these configurations are radially localized, such as narrow plasma ring pairs. Another is that the rotation frequency is nearly constant over the rings. Only axisymmetric local configurations consisting of solitary plasma rings or periodic sequences of rings are found when the gradient of the rotation frequency is (locally) significant. Assuming that the plasma pressure is scalar the problem is reduced to the solution of two coupled non-linear differential equations. One, the ``Master Equation'' [1], relates the magnetic surface function to the plasma rotation frequency that is connected to the gravity field. The other, the Vertical Equilibrium Equation, relates the plasma pressure gradient to both the Lorentz force and to the plasma density profile through the gravitational force.\\[4pt] [1] B. Coppi, $\it{Phys. Plasmas}$ $\bf{18}$, 032901 (2011). [Preview Abstract] |
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K1.00050: IGNITOR, ITER and NIF in the Context of the World Effort on Fusion Burning Plasmas E. Azizov, B. Coppi, E. Velikhov As of last summer, the ITER program has been recognized as being directed at providing an ``International Platform for Fusion Technology.'' Then, the two experimental programs that have the explicit goal to approach ignition conditions with D-T plasmas are NIF and IGNITOR. NIF, the National Ignition Facility, is based on the inertial confinement principle using a laser system capable of delivering 1.6 MJ and is being operated in Livermore. IGNITOR will be operated by the Kurchatov Institute within the research center of Troitzk presently owned by Rosatom and involves a high level collaboration between Italy and Russia. For this, Ignitor has been defined as a Flagship Project by Italy and the construction of its core has been funded. The Ignitor design is based on the experimental results obtained by the high field line of experiments carried out at MIT, within the Alcator Program, and in Italy within the Frascati Torus Program. A wide set of experiments in Japan, on high density plasmas, in the US, Russia and Europe have produced plasma physics results and technology developments that have guided the evolution of the Ignitor design. The main theoretical plasma physics issues to be dealt with in connection with this program are discussed. [Preview Abstract] |
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K1.00051: Incompatibility of FRC `Self--Colliding Beams' with Classical Large Orbit Theory and Experiment Bogdan Maglich Rosenbluth$^{1}$:\textit{ ``One key physics issue is the behavior of very large gyro radius systems, for which the usual thermal physics is inadequate.''- }Rostoker$^{2 }$ posited (1) 0.42 KeV d$^{+ }$ FRC can achieve confinement$^{ }\tau $ =30 s observed$^{3}$ in self-colliding orbits (SCO) of 725 KeV d$^{+}$,$^{ }$stabilized by magnet focusing$^{4}$ and electrons$^{5}$ ; (2) FRC result $^{6}\tau $=2 x10$^{-3}$ s is ``record long lived plasma state for advanced, aneutronic fuels ''; (3) non-intersecting collision-less orbits produce nuclear reactions. (i) B$_{z}$(r) of FRC is defocusing, field index n$>$0. From single particle orbit theory$^{7,8}$ destructive instability must occur with $\tau ^{ }\le $ 10$^{-3}$ s. (ii) $\tau $ cannot be scaled up by ion energy increase. (iii) Luminosity in SCO$^{3}$: L$\sim $10$^{31}$s$^{-1}$ cm$^{-2}$; in co-revolving FRC orbits: L=0 unless 2 species in same orbit, which requires v2/v1= z$_{1}$m$_{1}$/z$_{2}$m$_{2 }$and N$\tau \quad \sim $ 10$^{17 }$by Lawson$^{ 9-11}$. See http://www.aneutronicfusion.org 1. NIM271, p.1 (88); 2. PRL 70, 1818 (93); 3.PRL 54, 796 (1985); 4.PRL 29, 1590 (72); 5.PRL 70, 299 (93); 6.PRL 105, 045003-1,(10); 7.Part. Acc.1, (70); 8. AIP CP 311, 292 (93); 9. J.App.Phys.46, 2915 (75); 10. NIM A346 322 (93); 11.NIM 144, 65 (77) [Preview Abstract] |
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K1.00052: Electromagnetic waves in spin quantum plasmas Stefanie Braun, Felipe Asenjo, Swadesh Mahajan We derive dispersion relations for electromagnetic (EM) waves in spin quantum plasmas using a two-vorticity theory, describing the plasma in terms of vortical structures similar to the vortex dynamics of ideal fluids. Contrary to previous work, where the spin vector was usually assumed to be aligned with the background magnetic field, this enables us to include the spin as a dynamical variable of the system. The resulting dispersion relations consist of branches which can be identified with the modes found in classical calculations, modified by the spin effects, plus new quantum branches which lack a classical analog. We study the stability of these modes in the presence of sources of free energy, such as magnetic moment energy, due to an energetically non-optimal orientation of the spin in the magnetic field, or gradients in the equilibrium spin density. Whereas all the modes are stable in a minimum-energy configuration, some of them may become unstable once such sources are introduced. In the former case, the instability is limited to a narrow range of the wave number k, whereas in the latter case, although its growth rate is smaller, it is much more pervasive in k. If both sources are included simultaneously, the effects overlap. [Preview Abstract] |
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K1.00053: Simulations of induced nuclear reactions via electrostatic discharge in heavy-water hydrated dielectric media Grant Mathews, David Cappelletti We present numerical simulations of a novel concept for the low-cost initiation of D+D fusion reactions via electrostatic discharge in a dielectric medium. We have run simulations based upon a generalized fractal dielectric breakdown model to describe the development of bush-like and dendritic like discharge fractal structure in a dielectric crystal hydrated with heavy water, e.g. CuSO4$\cdot$5D2O. We have generalized this model to allow for not only the electronic discharge structure but also the acceleration of positive ions during the development of the discharge. Simulations suggest that the dendritic structures persist for more than 100 microseconds. For a large enough applied voltage this is ample time to accelerate the positive deuterium ions to energies sufficient to induce nuclear reactions. Prospects for applications and scalability of this device are discussed. [Preview Abstract] |
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K1.00054: Fission fusion hybrids- recent progress M. Kotschenreuther, P. Valanju, S. Mahajan, B. Covele Fission-fusion hybrids enjoy unique advantages for addressing long standing societal acceptability issues of nuclear fission power, and can do this at a much lower level of technical development than a competitive fusion power plant- so it could be a nearer term application. For waste incineration, hybrids can burn intransigent transuranic residues (with the long lived biohazard) from light water reactors (LWRs) with far fewer hybrid reactors than a comparable system within the realm of fission alone. For fuel production, hybrids can produce fuel for $\sim$4 times as many LWRs with NO fuel reprocessing. For both waste incineration or fuel production, the most severe kind of nuclear accident- runaway criticality- can be excluded, unlike either fast reactors or typical accelerator based reactors. The proliferation risks for hybrid fuel production are, we strongly believe, far less than any other fuel production method, including today's gas centrifuges. US Thorium reserves could supply the entire US electricity supply for centuries. The centerpiece of the fuel cycle is a high power density Compact Fusion Neutron Source (major+minor radius $\sim$ 2.5-3.5 m), which is made feasible by the super-X divertor. [Preview Abstract] |
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K1.00055: ABSTRACT MOVED TO S1.00066 |
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K1.00056: The design and implementation of Los Alamos PLasma Simulation (LAPS) code Alessandro Corbetta, Maria Missanelli, Cecilia Pagliantini, Laura Scarabosio, Gian Luca Delzanno, Zehua Guo, Bhuvana Srinivasan, Xianzhu Tang Los Alamos Plasma Simulation (LAPS) is an integrated modeling code based on a common-data framework for multiphysics simulation of both magnetic and inertial confinment fusion (ICF) plasmas. Its principal design goal is to provide a common data structure on computational grids and plasma states for different components of the multiphysics integration. LAPS provides an optimal mesh generation for one to three dimensional configuration space discretization and an adaptive mesh scheme that equi-distributes application-specified error. The plasma state is defined on this mesh. LAPS supports the solution of moment and kinetic equations using grids, particle-in-cell, Monte-Carlo, and molecular dynamics. The parallel data structure and (non)linear solvers for PDEs are based on PETSc, while the parallel data structure and communication for particle and Monte-Carlo method are native to LAPS. LAPS separates the numerical discretization from application PDEs. The initial focus is on spectral method, including the spectral element/volume and discontinuous Garlekin scheme for conservative PDEs. The initial set of applications for LAPS development include PIC modeling of plasma transport and rotation in field reversed configuration, fluid-moment and kinetic model of tokamak scrape-off layer. [Preview Abstract] |
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K1.00057: CPIC: a curvilinear Particle-In-Cell code for plasma-material interaction studies Enrico Camporeale, Gian Luca Delzanno We present a recently developed Particle-In-Cell (PIC) code in curvilinear geometry, CPIC (Curvilinear PIC), where the standard PIC algorithm is coupled with a grid generation/adaptation strategy. Through the grid generation strategy (based on Winslow's method), the code can simulate domains of arbitrary complexity, including the interaction of complex objects (with the simulation domain conforming exactly to the objects without any stair-stepping) with a plasma. At present the time-integration is explicit and the code is two-dimensional and electrostatic (only Poisson's equation is solved). It features a hybrid particle mover, where the computational particles are characterized by position in logical space and velocity in physical space. Poisson's equation is solved with preconditioned GMRES. We will present the application of the code to standard test problems such as plasma waves, two-stream instabilities, Landau damping and the charging of a spherical object in a plasma. We will also discuss techniques that can be used to reduce PIC noise, which can be critical when the ratio of the largest to the smallest cell volume becomes large. [Preview Abstract] |
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K1.00058: An Energy- and Charge-conserving, Implicit, Electrostatic Particle-in-Cell Algorithm in curvilinear geometry G. Chen, L. Chac\'{o}n, D.C. Barnes A recent proof-of-principle study proposes an energy- and charge-conserving, fully implicit particle-in-cell algorithm in one dimension [1], which is able to use timesteps comparable to the dynamical timescale of interest. Here, we generalize the method to employ non-uniform meshes via a curvilinear map. The key enabling technology is a hybrid particle pusher [2], with particle positions updated in logical space and particle velocities updated in physical space. The self-adaptive, charge-conserving particle mover of Ref. [1] is extended to the non-uniform mesh case. The fully implicit implementation, using a Jacobian-free Newton-Krylov iterative solver, remains exactly charge- and energy-conserving. The extension of the formulation to multiple dimensions will be discussed. We present numerical experiments of 1D electrostatic, long-timescale ion-acoustic wave and ion-acoustic shock wave simulations, demonstrating that charge and energy are conserved to round-off for arbitrary mesh non-uniformity, and that the total momentum remains well conserved.\\[4pt] [1] Chen, Chac\'{o}n, Barnes, \emph{J. Comput. Phys.} \textbf{230} (2011). \\[0pt] [2] Camporeale and Delzanno, \textit{Bull. Am. Phys. Soc. }\textbf{56}(6) (2011); Wang, et al., \textit{J. Plasma Physics}, \textbf{61} (1999). [Preview Abstract] |
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K1.00059: Lagrangian and Hamiltonian structure of magnetofluid models with gyroviscous-like contributions Alexander Wurm, P.J. Morrison Many magnetofluid theories, like ideal MHD and various reduced models, exhibit a noncanonical Hamiltonian structure when expressed in Eulerian variables [1]. Of particular interest are magnetofluid models that systematically include contributions due to finite ion gyro-radii. Building on the work of Ref. [2] we generalize the so-called gyro-map to three dimensional magnetofluid theories. Starting with the 3D ideal MHD noncanonical Poisson bracket [1] and a Hamiltonian including general gyroviscous terms, we derive equations of motions and compare them to, e.g., Braginskii [3] in the collisionless limit. In addition we explore the Lagrangian version of these theories which use Hamilton's principle to derive the equations of motion [4]. \\[4pt] [1] P.J.~Morrison and J.M.~Greene, Phys. Rev. A {\bf 45},790 (1980).\\[0pt] [2] P.J.~Morrison, I.L.~Caldas, and H.~Tasso, Z. Naturforsch. {\bf 39a}, 1023 (1984).\\[0pt] [3] S.I.~Braginskii, in {\it Review of Plasma Physics}, ed. M.A.~Leontovich (Consultants Bureau, New York, 1965), Vol. 1, p. 205.\\[0pt] [4] W.A.~Newcomb, Nuclear Fusion: 1962 Suppl. Part 2, p. 451. [Preview Abstract] |
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K1.00060: Qubit lattice representation of the Kelvin Helmholtz instability George Vahala, Linda Vahala, Jeffrey Yepez, Min Soe A qubit unitary lattice algorithm, which scales almost perfectly to the full number of cores available (e.g., 216 000 cores on a CRAY XT5), is used to examine the Kelvin Helmholtz (KH) instability for a mean shear layer between two fluids whose dynamics satisfy the nonlinear Schrodinger (NLS) equation. The ground state wavefunction of weakly interacting Bose-Einstein gas condensates satisfies the NLS. In the nonlinear stage, simulations of Takeuchi et. al. have indicated there are 2 basic instability mechanisms: the standard classical mechanism as well as a quantum mechanism dealing with the excitation of interface modes with negative energies. Singly quantized vortices are emitted from the regions of the sawtooth modes and propagate into each fluid. Our unitary qubit algorithm permits very detailed spatial resolution, much higher than that possible by standard algorithms. We compare and contrast our results to those of Takeuchi [Phys. Rev. B81, 094517 (2010)]. [Preview Abstract] |
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K1.00061: Potential formulation of the dispersion relation for a cold, magnetized plasma Robert Johnson The derivation of the dispersion relation for a cold plasma in a constant background magnetic field is reexamined in terms of the potential formulation of electrodynamics. Under the usual approximations for a neutral plasma neglecting ion flow and thermal stress, the linearized equation of motion for the electron flow describes only the electron cyclotron resonance when the ion contribution to the material response is included through the friction term. Only by addressing the nonlinear coupling of the perturbed electron flow to the perturbed potential can a more interesting solution be found. The coupling of the flow to its potential leads to resonance in the electron fluid whose frequency depends upon the inclination of the propagation vector from the direction of the background field. The plane wave solution for general propagation vector is determined for several cases of interest and compared to the helicon relation as commonly described in the literature. The presence of an electromagnetic oscillation in an otherwise uniform plasma induces a rotation of the magnetization vector away from the axis of the background field. [Preview Abstract] |
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K1.00062: How Stochastic Structural Stability Theory Relates to Traditional Statistical Closures J.B. Parker, J.A. Krommes The stochastic structural stability theory (SSST) is a technique\footnote{B. F. Farrell and P. J. Ioannou, J.\ Atmos.\ Sci.\ \textbf{60}, 2101 (2003).} that can be used for understanding the statistical behavior of drift-wave--zonal-flow systems.\footnote{B. F. Farrell and P. J. Ioannou, Phys.\ Plasmas \textbf{16}, 112903 (2009).} The method involves parameterizing the nonlinear DW--DW interactions as white noise while keeping the correct behavior of the DW--ZF interactions. The SSST can be interpreted as an intermediate step between the fundamental amplitude equations and conventional statistical closures. Unlike typical closures which describe only the mean-square ZF, the SSST retains a ZF amplitude. We discuss the relationship between the SSST and more traditional closures of the DW--ZF problem.\footnote{J.\ A.\ Krommes and C.-B.\ Kim, Phys.\ Rev.\ E.\ \textbf{62}, 8508 (2000).} In particular, we examine the physical content of a closure of the SSST equations, illustrating with the Generalized Hasegawa--Mima equation. Studies are also made of the Hasegawa--Wakatani system, extending and clarifying the work of Ref.~3. The ideas are relevant for the ultimate control of microturbulence. [Preview Abstract] |
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K1.00063: UNDERGRADUATE RESEARCH II |
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K1.00064: Understanding Blazar Variability through Kepler Paolo Di Lorenzo, Daniel Silano, Paul Wiita, Ann Wehrle, Stephen Unwin Our Kepler program has monitored optical emission from four blazars over the past two years. We currently have 7 quarters of long cadence (30 min) and one or two quarters of short cadence (1 min) data for each AGN. These lengthy, nearly continuous, data sets provide a unique resource for studying the nature of radio loud quasar variability. Any periodicity or quasi-periodicity in these light curves might indicate a bright feature, or hot spot, in the accretion disk or a helical structure in the relativistic jet. The standard pipeline for reducing Kepler data is designed for searching for planetary transits and removes real blazar variability, while the raw data contain numerous instrumental effects. Carefully decotrended data provide the best true light curves. We have calculated power spectral densities and Lomb-Scargle periodograms for these decontrended blazar light curves. We have not yet seen any large flares or identifiable periods in the data and so the variations we do see are most likely due to turbulence in the jet. [Preview Abstract] |
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K1.00065: Modeling and Classifying X-Shaped Radio Galaxies Julian Starr, Robert Sobczak, Paul Wiita While there are several explanations for the formation of the apparently modest subset of radio galaxies that display an X-shaped morphology (XRGs), an important but often overlooked aspect of observing XRGs is the classification uncertainties arising from projection effects. These XRGs have hot-spots in one set of primary lobes, as is typical for powerful RGs, but also have a greatly offset pair of secondary lobes that lack hot-spots. To determine the likelihood of a true XRG appearing non-X-shaped, we developed a computer algorithm to model fiducial XRGs and then rotated the models by random angles so as to develop probabilities that observations would lead to classification errors due to projection effects. We show that XRGs may be misclassified as showing Z-shaped, winged, standard double, and double-double morphologies. A ``perfect'' XRG, that is, one with perpendicular, equal-sized primary and secondary lobes, may appear as having a different morphology $\sim $20{\%} of the time. Thus many true XRG sources can be misclassified, significantly affecting the number that are known to exist. The double-double RGs are very rare and usually are interpreted as manifestations of restarted jet activity; however, a substantial fraction of them may really be XRGs viewed at special angles. [Preview Abstract] |
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K1.00066: Solar System Radio Astronomy at The College of New Jersey Joseph Benigno Our group at The College of New Jersey built a double dipole radio telescope as a contribution to NASA's Radio JOVE Program. We present observations of flares from Jupiter and the Sun and we give a brief description of the dominant physical mechanisms producing the radio waves from these two dominant sources of solar system radio emission. More recently we have built a basic radio interferometer with an 80 m baseline using two of these Radio JOVE double-dipoles. We describe the principles of interferometry as applicable to this telescope and present preliminary measurements made with this simple interferometer. [Preview Abstract] |
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K1.00067: Implementing an External Charge Injection System into the ILC-SiD KPiX ASIC for Charged-Particle Tracking Characterize Sheena Schier, Bruce Schumm KPiX 9 is a 512 channel ASIC designed by SLAC that is competing to perform detector readout for the International Linear Collider (ILC) and is currently the only readout chip that aims to fulfill both tracking and calorimetry needs for the ILC. To achieve the efficiency standard set for charged-particle tracking in the ILC a 1fC threshold; therefore, we need to understand the gain to 1fC as well. We connected an ECIS to 4 of the 6 bonded out channels in order to inject charges down to 1fC without distortion from internal calibration offsets. During the ILC beam spill, KPiX acquires up to 4 signals; our current analysis is restricted to the first acquisition only. Only 3 of the 4 ECIS channels were observable and displayed charge sensitivity down to around 2.5fC. The expected gain is -75mV/fC and the expected zero offset is at 2500mV; the gains and offsets are inverted by the amplifier. The average gain for the sensitive region is -72.8mV/fC with RMS 1.15mV/fC, with average voltage offset 2587mV with RMS 37.9mV. The gain curves are consistent and flatten out together along the charge axis. The average minimum threshold is 2.5fC with RMS 0.11fC. We conclude that the first acquisition of the KPiX ASIC is not efficient for ILC tracking and are now working to understand the other three acquisitions. [Preview Abstract] |
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K1.00068: GENERAL PHYSICS |
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K1.00069: The Big Bang, Genesis, and Knocking on Heaven's Door Robert Gentry Michael Shermer recently upped the ante in the big bang-Genesis controversy by citing Lisa Randall's provocative claim (Science 334, 762 (2011)) \textit{that ``it is inconceivable that God could continue to intervene without introducing a material trace of his actions.''} So does Randall's and Shermer's agreement that no such evidence exists disprove God's existence? Not in my view because my 1970s \textit{Science}, \textit{Nature }and \textit{ARNS }publications, and my article in the 1982 AAAS Western Division's Symposium Proceedings, \textit{Evolution Confronts Creation, } all contain validation of God's existence via discovery of His Fingerprints of Creation and falsification of the big bang and geological evolution. These results came to wide public/scientific attention in my testimony at the 1981 Arkansas creation/evolution trial. There ACLU witness G Brent Dalrymple from the USGS -- and 2005 Medal of Science recipient from President Bush -- admitted I had discovered a tiny mystery (primordial polonium radiohalos) in granite rocks that indicated their almost instant creation. As a follow-up in 1992 and 1995 he sent out SOS letters to the entire AGU membership that the polonium halo evidence for fiat creation still existed and that someone needed to urgently find a naturalistic explanation for them. Is the physics community guilty of a Watergate-type cover-up of this discovery of God's existence and falsification of the big bang? For the answer see www.halos.tv. [Preview Abstract] |
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K1.00070: Silicon Detector System and Noise Modeling Chan Ho Park, Richard Kyung We can postulate that dark matter are WIMPS, more specifically, Majorana particles called neutralinos floating through space. Upon neutralino-neutralino annihilation, they create a greater burst of other particles into space: these being all kinds of particles including anti-deuterons which are the indications of the existence of dark matter. For the development of the silicon detector, many factors including noise, shaping times and leakage current are considered. It is also an object of this study to find out factors affected by parallel noise such as leakage current and parallel resistance. High noise is not desirable, so we tried to avoid noise because it blurs the accurate readings that measure the x-ray signatures by adding a passivation material. We searched for the optimal resolution at which the FWHM is at a minimum at a specific shaping time, and for this, we used different shaping times to find the optimal resolution. Results shows where the paint/passivation material affects, and when is the best shaping time for the resolution measurement. [Preview Abstract] |
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K1.00071: The Enigma of Consciousness Shantilal Goradia The natural log of the age of the universe, 10E60 Plank times, is about 137 which, of course, does not precisely relate to the fine structure constant for a reason proposed in physics/0210040 (Pl. read it first) and elaborated here. It may take, more or less, 10 Planck times for a particle to send a message, making nature's alphabet 2E10 = 1024 or one kilobyte. Not knowing the exact language of nature, we can approximate total messages between 10E59 and 10E60. Considering each message to be a probability gives the natural log of all probabilities closer to 137. Particles moving at relativist speeds create illusions of x dimensions for x Planck times per message. Number of such dimensions (say 6 or 10) may be message dependent, explaining why we need string theories with different dimensions. If particles send messages, consciousness originates in particles per my book ``Quantum Consciousness - The Road to Reality.'' The uncertainty to us is a result of us not understanding the conscious decision of the particles. This supplements my oral presentation. [Preview Abstract] |
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K1.00072: SUPPLEMENTAL ABSTRACTS |
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K1.00073: To the measurement of the radius via an electron scattering Bogdan Wojtsekhowski We propose an experiment for an accurate measurement of the proton radius. A key feature of our proposal is an iron-free magnetic spectrometer. Projected systematics uncertainties will allow a 1{\%} level accuracy for the rp value. [Preview Abstract] |
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K1.00074: New diquark evidence in the nucleon Bogdan Wojtsekhowski The flavor decomposition of the nucleon electromagnetic form factors shows new evidence of the diquark in the nucleon. We will discuss recent experimental results and review other observations which indicate diquarks. Several 12-GeV experiments at JLab will also be sensitive to the diquark component of the nucleon w.f. [Preview Abstract] |
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K1.00075: Energy Analysis and law of universal repulsion Yongquan Han My understanding of energy is as follows: energy is invisible; for this reason, from this perspective it is more accurate to define energy as dark energy. Actually, energy must depend on its carrier. If the carrier is visible, the energy is visible; if the carrier is invisible, the energy is invisible. However, energy does exist, for motion is the everlasting theme. Law of universal repulsion ------All objects in the universe repel each other. Repulsion between two objects is directly proportional to the external energy (mv$^{2}$) of their relative motion and indirectly proportional to their relative motion radius (one object is in relative rest, while the other one is in relative motion). Application examples: Suppose a man whose mass is100 kg, runs on the earth at a speed of 10 meters per second. The radius of the earth is 637100 meters. The repulsion between the earth and the man is: F=mv$^{2}$/r=0.00157N; if his speed reaches the first cosmic speed ( 7.9 km per second ), then calculate: F=mv$^{2}$/r=980N, just overcome the gravity of the earth. [Preview Abstract] |
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K1.00076: Maximum entropy Fourier power spectrum for irregularly sampled data Robert Johnson The principle of maximum entropy is applied to the spectral analysis of a data signal with general covariance matrix and containing gaps in the record. The role of the entropic regularizer is to prevent one from overestimating structure in the spectrum when faced with imperfect data. Several arguments are presented suggesting that the arbitrary prefactor should not be introduced to the entropy term. The introduction of that factor is not required when a continuous Poisson distribution is used for the amplitude coefficients. The result of including the entropic measure factor is to suggest a spectrum consistent with the variance of the data which has less structure than that given by the forward transform, thus providing a more conservative estimate in light of experimental noise. An application of the methodology to example data derived from stellar observations is demonstrated. [Preview Abstract] |
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K1.00077: Galactic and black hole evolution from NBWF cosmology Wayne R. Lundberg The No-boundary Wave Function approach to cosmology has been shown consistent with the standard picture of inflationary cosmology under specific conditions. Considering these conditions to be empirically selected creates new areas for observational confirmation. Oscillatory evolution of the scalar field $\Phi $(t) indicates repeated mini-bang events in the early universe. This result is supported by observations of early structure formation, and that Ultra-high Energy Cosmic Rays and Gamma-Ray bursts are not found to have Active Galactic Nuclei as their source. More recent observations of super-massive black holes in unusually small elliptical galaxies indicate that the current relation between BH mass and host galaxies needs revision. Introduction of a gedanken for dark matter evolution in relation to cosmological structure and galactic cluster formation creates a new and more consistent interpretation of a host of observations. [Preview Abstract] |
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K1.00078: MEST-Tyche will take its dark comets to impact our solar system in 20 years Dayong Cao Tyche has many dark comets like Oort cloud. It went near our solar system every 25-27 million years. It could take its dark comets to impact our earth. Tyche and its dark comet absorb light like a dark light which is a negative black-body radiation. (1) $E_dd{\nu}=-\frac{{c_{1d}}{\nu_d}^3{d{\nu}}}{e^{{c_{2d}}{\nu_d}/{T_d}}-1}$. Among it, $E_d$: the dark energy, $\nu_d$: the dark frequence, $T_d$: the dark temperature, $c_{1d} ,c_{2d}$: the constant. So when they go near us, their wave has a against Doppler redshift as 0.000165. And they will inbreak solar system at the rate of 99AU/y, from the distance of 1,500AU and in 20 years. It can cause the broken ozonosphere, the lithosphere to crack, many big activity volcanic and the continental drift. And it can darked the light and colded the climate to the Great Ice Age. Not only it will break our environment by a special ``nuclear explosion'' under low temperature, but also the dark life will change the Genetic code of our life. So it will kill many lives and will produce new life. So it could trigger the Mass Extinction. We can bulid up a new pair of nuclear reactor (include dark nuclear energy) to drive a universal craft and can change the orbit of our earth for evading the impaction. We need a new life-information technology to develop our life and consciousness. [Preview Abstract] |
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K1.00079: MEST-The dark hole, dark comet and dark matter are the space-time center Dayong Cao The model of dark matter such as dark hole (black hole), dark comet and dark light have the space-time center. The wave is the space-time. Because the dark matter is space-time center, so it has the ``negative'' mass.(http://meetings.aps.org/link/BAPS.2011.MAR.K1.68) (1) $G\frac{m_1m_2}{r^2}=-\frac{G}{c^4}\frac{E_1E_2}{r^2}$. (2) $\frac{1}{4\pi\varepsilon_0}\frac{q_1q_2}{r^2}=-\frac{\mu_0{c^2}}{4\pi}\frac{q_1q_2}{r^2}$. Among it, m: the mass, r: the displacement, E: the energy, $q$: the quantity of electricity. Like charges repel each other, unlike charges attract; Like magnetic attract, unlike magnetic repel each other. Unlike mass repel each other, like mass attract; like energy repel each other, unlike energy attract. So the dark matter has a repulsive force to the stellar matter. So it can cause the discrepancy between the rotation curves. The nuclear of atom has antielectron. The proton (energy particle) get its charge; the neutron (mass particle) get its mass. It is a new atomic model. Like isospin repel each other, unlike isospin attract, Like spin attract, unlike spin repel each other. The dark nucleus is made up of the isospin and spin particle-space-time particle such as dark photon and dark neutrino. The space-time center of dark light of dark matter has valence mass-valence neutron and valence energy-valence proton. The dark light can take a reaction with neutrino. So we can use neutrino to find it. (3) $D^{-n}+\nu_e\rightarrow{p}+e$. (4) $D^{-p}-\nu_e\rightarrow{n}-e$. Among it, D: the center of dark light, $-n$: the negative valence neutron, $\nu_e$: electron neutrino, p: proton, $e$: electron. [Preview Abstract] |
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K1.00080: POST-DEADLINE ABSTRACTS |
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K1.00081: Forward-Backward Asymmetry in Top Quark Production at CDF II Ryan Edgar The CDF and D0 experiments have previously reported a significant production angle asymmetry in top quark pair creation at the Tevatron. Here, we present a new CDF measurement utilizing the statistical precision of the full Run II data set (2.3X previous) and a more general treatment of the differential asymmetry in both mass and rapidity. The results are compared to the NLO standard model and the previous measurements. [Preview Abstract] |
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K1.00082: Testing extensions of General Relativity using the latest cosmological data sets Jacob Moldenhauer, Jason Dossett, Mustapha Ishak We place constraints on cosmological models described as extensions of General Relativity, or modified gravity models, using the latest cosmological observations for both expansion and growth history. These models have been shown to give an alternative explanation for the observed accelerated expansion of the universe. We use the recently refined HST-COSMOS weak lensing tomography data, the ISW-galaxy cross correlations from 2MASS and SDSS LRG galaxy surveys, the matter power spectrum from SDSS-DR7, the WMAP7 temperature and polarization spectra, the BAO from the WiggleZ survey, and the Union2 compilation of type Ia supernovae, in addition to other bounds from Hubble parameter measurements and the Big Bang Nucleosynthesis. We use a few recent parameterizations of modified gravity to test the models for consistency with the data sets. Models which are inconsistent will be ruled out as possible explanations for the cosmic acceleration, while consistent models will have more support as competitive cosmological models. [Preview Abstract] |
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K1.00083: Using the measurability of spin to test the cosmic censorship conjecture Madeline Wade, Jolien Creighton In anticipation of the new era of gravitational wave detectors, it is especially important to develop methods for gaining information about astrophysical systems from gravitational wave signals. We have been working on developing a method for testing the cosmic censorship conjecture using the inspiral portion of the compact binary coalescence gravitational waveform. The cosmic censorship conjecture states that any massive body undergoing complete gravitational collapse must result in a singularity concealed by an event horizon, meaning this singularity will not be visible to a distant observer. The method we are developing will allow us to say whether detected systems are consistent with the cosmic censorship conjecture, within the context of the Kerr geometry, or are more exotic horizon-less systems. The Kerr geometry places an upper limit on the allowed spin of a compact object with a horizon. We use parameter estimation techniques to calculate the measurability of a spin and mass parameter appearing in the gravitational waveform. The Kerr limit on spin along with a physical limit on the mass parameter allows us to say whether a system is consistent with a Kerr black hole within our calculated measurement error. [Preview Abstract] |
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K1.00084: Absolutely relativity Mohsen Lutephy The light speed constancy is proved here and then it is not a principle suppose it is a proposition proved absolutely based on the Galilean transformation and simultaneity and this is a book full from new discoveries along the absolutely proof for Lorentz transformation. Even in a page I have proved Lorentz transformation by the brawer constant point based on the Galilean transformation until to show easily it is possible to generate absolutely relativity and this is not ether theorem suppose we are upon the new discoveries all mathematical and complete, not a theory. [Preview Abstract] |
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K1.00085: Correlation study of atmospheric/space weather and cosmic ray flux variation Mathes Dayananda, Xiaochun He In recent years, there has been a growing interest of understanding the effects of cosmic ray radiation on Earth's climate and environment, particularly on average global temperature. Discoveries suggest that climate variability is at least partially linked to changes in cloud cover influenced by changes in the cosmic ray muon and neutron flux [1]. The recent findings also indicate that there is a correlation between cosmic rays and ozone depletion, especially the polar ozone over Antarctica [2]. At Georgia State University (GSU) we are working on a long-term measurement of secondary cosmic ray flux distribution and are focusing on studying the correlations among variations of cosmic ray flux and atmospheric/space weather. In this talk, we will present the preliminary results from our cosmic ray flux detector measurements which are currently taking data at GSU. \\[4pt] [1] Nigel D. March and Henrik Svensmark, Low Cloud Properties Influenced by Cosmic Rays, Phys. Rev. Lett. 85, 23 (2000).\\[0pt] [0pt][2] Q.-B. Lu, Correlation between Cosmic Rays and Ozone Depletion, Phys. Rev. Lett. 102, 118501 (2009). [Preview Abstract] |
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K1.00086: Study of Cosmic Ray Muon Flux Variation with Atmospheric Weather Xiaohang Zhang, Mathes Dayananda, Xiaochun He Global climate change, driven by a variety of natural factors both on the planet and from outer space, has been a constant throughout the history of the earth. The variability of and interactions among these factors have been researched for decades. The relationships between cosmic ray radiation and other climate factors have been studied by many researchers, such as atmospheric pressure and temperature [1], low cloud coverage [2], and ozone depletion [3], etc. Over the past several years, various cosmic ray telescopes were built and have been measuring long-term cosmic ray muon flux at different spots in Georgia State University (GSU), A series of correlations between cosmic ray muon flux and local atmospheric weather have been being studied. The preliminary results from our recent measurement and research will be presented. \\[4pt] [1] Serap Tilav, et al., Atmospheric Variations as Observed by IceCude, Proceedings of the 31st ICRC, (2009).\\[0pt] [2] Nigel D. March and Henrik Svensmark, Low Cloud Properties Influenced by Cosmic Rays, Phys. Rev. Lett. 85, 23 (2000).\\[0pt] [3] Q.-B. Lu, Correlation between Cosmic Rays and Ozone Depletion, Phys. Rev. Lett. 102, 118501 (2009). [Preview Abstract] |
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K1.00087: Analysis of open bottom production in 500 GeV p+p collisions using the PHENIX detector Laura Patel Dilepton pairs resulting from the fragmentation and decay of open charm (DD) and open bottom (BB) mesons are an important tool to probe the hot and dense matter created from nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC). In the high mass region, between the $J/\Psi$ and $\Upsilon$ resonances, the dilepton mass spectrum will be dominated by the semi-leptonic decay of pairs of D mesons and B mesons. The status of the analysis of correlated like-sign dimuons from pairs of B mesons of $\sim 6.3 pb^{-1}$ data from p+p collisions at $\sqrt{s}=500$~GeV within the PHENIX muon arms acceptance ($1.2 < |y| < 2.2$) will be presented. In the mass region between 4.5 and 12 GeV, the only source of primary correlated like-sign dimuon pairs will come from the decay of B meson pairs, due to neutral meson particle-antiparticle mixing. Using the properties of B-meson decays the differential cross section can be calculated. In the future, this analysis method could be applied to the $\sqrt{s}=200$~GeV p+p collisions in order to determine a baseline for d+Au and Au+Au. [Preview Abstract] |
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K1.00088: InFOC\textbf{$\mu $}S: A Balloon Instrument with $<$10 Arc Second Hard X-ray Imaging Jack Tueller, Willian Zhang, Scott Barthelmy, Akihiro Furuzawa, Yoshito Haba, Hans Krimm, Hideyo Kunieda, Takashi Okajima, Takuya Miyazawa, Richard Mushotzky, Kesuke Tamura, Yuzuru Tawara The International Focusing Optics Collaboration for $\mu $Crab Sensitivity (InFOC$\mu $S) is currently funded to develop balloon payload with a multilayer hard X-ray telescope based on slumped glass technology similar to NuSTAR, but fully utilizing the IXO technology to achieve a spatial resolution of $<$10 arcseconds (PSF area $<$1/25 of NuSTAR). The key science goal for this technology is a deep hard X-ray survey to understand role of AGN/black holes in the formation of galaxies. Due to obscuration, this can only be achieved in the hard X-ray band, where absorption is insignificant and that only hard X-ray measurements can unambiguously determine the luminosities of individual AGN. InFOC$\mu $S will demonstrate the technology necessary to resolve the cosmic hard X-ray background missed by NuSTAR, which can only resolve 45-65{\%} of the background due to source confusion, and make a complete census of black hole growth at the peak of their formation between z=0.5 and z=2. We will present our approach to high spatial resolution hard X-ray imaging at low cost, which will be demonstrated by a resolved image of the Crab Nebula from a balloon and can be scaled to a deep-survey Explorer mission. InFOC$\mu $S is being prepared for a flight in the fall of 2013. [Preview Abstract] |
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K1.00089: Revealing nearby failed supernovae with megaton neutrino telescopes Lili Yang, Cecilia Lunardini We study the detectability of neutrino bursts from nearby direct black hole-forming collapses at Mt class detectors. Due to their high energetics, these bursts could be identified -- by the time coincidence of $N\geq 2$ or $N\geq 3$ events within a $\sim 1$ s time window -- from as far as $\sim 4-5$ Mpc away. This distance comprises several major, supernova-rich galaxies, so that failed supernova bursts could be detected at a rate of up to one per decade, comparable to the expected rate of the more common, but less luminous, neutron star-forming collapses. Thus, the detection of a failed supernova within the lifetime of a Mt detector is a realistic possibility. It might give the first evidence of direct black hole formation, with important implications on the physics this phenomenon. [Preview Abstract] |
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K1.00090: The most basic laws of movement Yongquan Han In nature, any movement of the object is a curve, in the process of motion by at least two forces, the two opposite direction of force moment, or a force component and another force in the opposite direction, and the effect on the same object motion curve, the two a force is the attraction and repulsion. Analysis one: when gravity is greater than or equal to the repulsive, objects can be attached to another object, as are attached to rotate together (at this time , the attraction force and repulsion force may in the opposite direction) may also be an object around another object. Or finally attached to another object (for example, velocity smaller projectile motion). Analysis two: when the repulsive force greater than gravity, objects from the attached objects do eccentric exercise. The final result is: the object which is attached around a circular motion, repulsion and attraction to reach dynamic equilibrium. Or completely escape from the attached objects. Analysis three: when people stand on the earth, the movement is a circular motion whose repulsion greater than the gravitational ,at this time, the component of gravity and repulsion force in the opposite direction, the size of approximately equal. [Preview Abstract] |
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K1.00091: First light at the HAWC high altitude TeV gamma ray detector in Mexico Daniel Fiorino The High Altitude Water Cherenkov (HAWC) Observatory -- currently under construction at 4100m altitude at Pico de Orizaba in Mexico -- is a high duty cycle, large field of view detector for gamma rays at TeV energies. The HAWC Observatory will locate and provide spectra for extended and point sources of TeV gamma rays, probe the cosmic ray anisotropy, search for gamma ray bursts, and set limits on extragalactic background light. Data taking at our smaller test array (VAMOS) is currently under way. I will present results of a first study of several months of VAMOS data, including a first skymap, performance tests, and a search for the shadow of the moon in cosmic rays. [Preview Abstract] |
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K1.00092: Status of ongoing R{\&}D for the EXO-GAS experiment Kirill Pushkin The EXO collaboration searches for neutrinoless double beta decay using 80{\%} isotopically enriched Xenon ($^{136}$Xe) to measure neutrino mass and probe its Majorana nature. A 200 kg liquid phase detector is currently running at WIPP. EXO is also conducting R{\&}D on a high pressure xenon gas detector using natural Xe, with pressures of 1-10 atm. This technique may offer superior energy resolution than a liquid Xenon detector and may allow discrimination between single and double electron events thus suppressing detector background. A high pressure xenon detector would use secondary scintillation light to enhance energy resolution. Achieving good energy resolution requires very low concentration of electronegative impurities in the gas and, therefore, needs to exploit reliable purification techniques. Another opportunity offered by the gaseous phase may be to detect Ba$^{++}$ ions which could be transported by high electric fields through the gas to a nozzle, extracted into a lower pressure region and detected in order to separate signal events from radioactive background. The status of the EXO-GAS experiment, its detector design, construction, Ba$^{++}$ identification, gas handling system, purification, and vacuum-sampling system will be presented. [Preview Abstract] |
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K1.00093: Progress towards an atomic EDM measurement of Ra-225 Richard Parker, Kevin Bailey, Matthew Dietrich, John Greene, Roy Holt, Mukut Kalita, Wolfgang Korsch, Zheng-Tian Lu, Peter Mueller, Tom O'Conner, Jaideep Singh We are searching for the permanent electric dipole moment (EDM) of the Radium-225 nucleus. A nonzero nuclear EDM is a signature of CP- and T-violating interactions within nuclei. Currently, the best experimental limits on these interactions are derived from EDM measurements of Mercury-199. The Ra-225 radioisotope (half-life of 15 days) is an attractive alternative because, due to its peculiar shape (nuclear octupole deformation), it is predicted to be a few hundred to a few thousand times more sensitive to these types of interactions than Hg-199. In our measurement scheme, Ra atoms are first laser cooled and trapped in a magneto-optical trap and then transferred to an optical dipole trap (ODT), both of which have already been demonstrated. The ODT is moved to a magnetically-shielded science chamber, and then the atoms are transferred to a perpendicular ODT in which the EDM will be measured. Transfer efficiencies between the two ODT's as high as 60{\%} have been demonstrated. We will report on progress towards measurements of atomic properties necessary for the EDM search and the EDM search itself. Research supported by DOE, Office of Nuclear Physics, contract No. DE-AC02-06CH11357. [Preview Abstract] |
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K1.00094: ABSTRACT WITHDRAWN |
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K1.00095: A buffer gas source of YbF molecules Sarah Skoff, Nick Bulleid, Didier Nohlmans, Richard Hendricks, Daniel Segal, Ben Sauer, Ed Hinds, Mike Tarbutt Using a cryogenic buffer gas source, with both continuous and pulsed helium flow, we have produced cold, slow beams of YbF molecules. The flux exceeds 10\^{}10 ground state molecules per shot per steradian, the translational and rotational temperatures are 4K, and the speed is between 130m/s and 320m/s depending on the flow regime. We use absorption imaging to follow the dynamics inside the cell [1], we observe the onset of turbulence in the cell, and we relate this to the beam extraction efficiency. We have injected this beam into an electric decelerator, we plan to use the beam to improve the measurement of the electron's electric dipole moment [2] and are currently starting experiments to trap the molecules using permanent magnets. \\[4pt] [1] S.M. Skoff et al., Phys. Rev. A 83, 023418 (2011)\\[0pt] [2] J. J. Hudson, D. M. Kara, I. J. Smallman, B. E. Sauer, M. R. Tarbutt and E. A. Hinds, Nature 473, 493 (2011) [Preview Abstract] |
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K1.00096: Reflection-asymmetric Nuclear Deformations within the Density Functional Theory Erik Olsen, Jochen Erler, Witek Nazarewicz, Mario Stoitsov Within the nuclear density functional theory (DFT) we study the effect of reflection-asymmetric shapes on ground-state binding energies and binding energy differences. To this end, we developed the new DFT solver AxialHFB that uses an approximate second-order gradient to solve the Hartree-Fock-Bogoliubov equations of superconducting DFT with the quasi-local Skyrme energy density functionals. Illustrative calculations are carried out for even-even isotopes of radium and thorium. [Preview Abstract] |
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K1.00097: Field Theory Thermalization from Gravitational Collapse in String Theory Mary Hemmeter, Leopoldo Pando Zayas, Dori Reichmann, David Garfinkle Motivated by gauge/gravity correspondence, we numerically investigate gravitational collapse in 5-dimensional asymptotically AdS space-time. We consider various scalar fields: minimally coupled massless, massive and, for the first time, fields with string theoretic potential. After establishing various general aspects of collapse such as the relation between the black hole formation time and its optical approximation, we focus on the study of Choptuik scaling. Namely, we study the threshold of black hole formation and establish the universal scaling law $M_{BH} \propto |p-p^*|^{\gamma}$ which relates the mass of the formed black hole to a parameter p in the initial profile of the scalar field where the critical parameter p* constitutes the criterion for black hole formation ($\gamma \approx $0.41). We aim to provide numerically accurate values for the universal factor $\gamma $ and to investigate its place in the dual interpretation. Finally we address the question of the stability of AdS space with respect to black hole formation under arbitrarily small perturbations and its implication for thermalization in field theory. [Preview Abstract] |
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K1.00098: Neutron Star - Magnetosphere Interactions Marcelo Ponce, Matthew Anderson, Luis Lehner, Steven L. Liebling, Carlos Palenzuela In this work we report results of the interaction of a neutron star magnetosphere in both collapsing and moving scenarios interacting with an ambient magnetic field. In recent works [1,2], it has been shown the important role and realism associated with studies of electromagnetic environments in some particular regimes, such as: ideal-MHD, force-free, and electro-vacuum. Motivated by this and their astrophysical implications for BBH and hybrid BH-NS mergers [3,4], we study the following cases: collapse of a magnetized NS, head-on collision of a BH-NS, and orbiting merger of a BH-NS. Based in the results from our simulations, we draw some relevant conclusions to the production of jets as described within the force-free formalism. \\[4pt] [1] C.Palenzuela, L.Lehner and S.Liebling, Science {\bf 329}, 927 (2010).\\[0pt] [2] C.Palenzuela, T.Garrett, et al., Phys.Rev.D {\bf 82}, 044045 (2010).\\[0pt] [3] L.Lehner, C.Palenzuela, et al., 2011.\\[0pt] [4] S.Liebling, L.Lehner, et al., Phys.Rev.D {\bf 81}, 124023 (2010). [Preview Abstract] |
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K1.00099: Improvement on Mass Spectrum Calculations for Ground State Pseudoscalar and Vector Mesons in Light Front Quark Model Ziyue Li, Ho-Meoyng Choi, Chueng-Ryong Ji We improved the meson mass spectra calculation done with the light-front quark model constrained by the variational principle for the QCD-motivated effective Hamiltonian. By smearing out the dirac delta function in the hyperfine interaction, we were able to avoid the negative infinity one encounters when using variational principle for the entire hamiltonian. We obtained a better fitting for the mass spectrum of ground state pseudoscalar and vector mesons from $\pi$ to $\Upsilon$, compared to the already very good results from previous calculation that didn't include hyperfine interaction in the parameterization process. Our new parameters are further tested in decay constant calculation. We showed that by including higher order Harmonic Oscillator (HO) basis in our trial wave funciton, the decay constants calculated from our model can be improved to agree reasonably well with the experiments. [Preview Abstract] |
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