(NATIONAL SPHERICAL TORUS EXPERIMENT) STRUCTURAL DESIGN CRITERIA
Princeton Plasma Physics Laboratory
NSTX (NATIONAL SPHERICAL TORUS EXPERIMENT) STRUCTURAL DESIGN CRITERIA NSTX-CRIT-0001-01 February Design Criteria Revision 1 RECORD OF REVISIONS REVISION DATE ECP DESCRIPTION OF CHANGE 0 AUGUST 2003. STRUCTURAL CRITERIA
Implementation of BN Control in the National Spherical Torus...
Office of Scientific and Technical Information (OSTI)
the normalized B in the National Spherical Torus Experiment M. Ono, et al., Nuclear Fusion 40, 557 (2000). A PID operator is applied to the difference between the present value...
November 10, 1998 Physics Design of the National Spherical Torus
1 Abstract The mission of the National Spherical Torus Experiment (NSTX) is to prove the principles an attractive path to a reactor or Volumetric Neutron Source (VNS). The ST fusion core would be small, economic and is presently under construction. Various reactor concepts have been advanced for the ST, 7,8 and these have
Primary ELM filament structure in the National Spherical Torus Experiment
Princeton Plasma Physics Laboratory
Primary ELM filament structure in the National Spherical Torus Experiment R. J. Maqueda,1 R. Maingi modes give rise to plasma filaments that burst radially outward during the non-linear phase to study the evolution and characteristics of the post-ELM filaments. These edge filaments, which are well
Vessel eddy current measurement for the National Spherical Torus Experiment
Gates, D.A.; Menard, J.E.; Marsala, R.J. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)
2004-12-01
A simple analog circuit that measures the National Spherical Torus Experiment (NSTX) axisymmetric eddy current distribution has been designed and constructed. It is based on simple circuit model of the NSTX vacuum vessel that was calibrated using a special axisymmetric eddy current code which was written so that accuracy was maintained in the vicinity of the current filaments [J. Menard, J. Fusion Tech. (to be published)]. The measurement and the model have been benchmarked against data from numerous vacuum shots and they are in excellent agreement. This is an important measurement that helps give more accurate equilibrium reconstructions.
Divertor Heat Flux Mitigation in the National Spherical Torus Experiment
Soukhanovskii, V A; Maingi, R; Gates, D A; Menard, J E; Paul, S F; Raman, R; Roquemore, A L; Bell, M G; Bell, R E; Boedo, J A; Bush, C E; Kaita, R; Kugel, H W; LeBlanc, B P; Mueller, D
2008-08-04
Steady-state handling of divertor heat flux is a critical issue for both ITER and spherical torus-based devices with compact high power density divertors. Significant reduction of heat flux to the divertor plate has been achieved simultaneously with favorable core and pedestal confinement and stability properties in a highly-shaped lower single null configuration in the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 2000] using high magnetic flux expansion at the divertor strike point and the radiative divertor technique. A partial detachment of the outer strike point was achieved with divertor deuterium injection leading to peak flux reduction from 4-6 MW m{sup -2} to 0.5-2 MW m{sup -2} in small-ELM 0.8-1.0 MA, 4-6 MW neutral beam injection-heated H-mode discharges. A self-consistent picture of outer strike point partial detachment was evident from divertor heat flux profiles and recombination, particle flux and neutral pressure measurements. Analytic scrape-off layer parallel transport models were used for interpretation of NSTX detachment experiments. The modeling showed that the observed peak heat flux reduction and detachment are possible with high radiated power and momentum loss fractions, achievable with divertor gas injection, and nearly impossible to achieve with main electron density, divertor neutral density or recombination increases alone.
November 10, 1998 Physics Design of the National Spherical Torus
NSTX is to prove the principles of spherical torus physics by producing high- t plasmas that are non an attractive path to a reactor or VolumetricNeutron Source VNS.The ST fusion core would be small under construction. Various reactor concepts have been advanced for the ST,7,8 and these have identi ed
Simulation of microtearing turbulence in national spherical torus experiment
Guttenfelder, W.; Kaye, S. M.; Bell, R. E.; Hammett, G. W.; LeBlanc, B. P.; Mikkelsen, D. R.; Ren, Y.; Candy, J.; Nevins, W. M.; Wang, E.; Zhang, J.; Crocker, N. A.; Yuh, H.
2012-05-15
Thermal energy confinement times in National Spherical Torus Experiment (NSTX) dimensionless parameter scans increase with decreasing collisionality. While ion thermal transport is neoclassical, the source of anomalous electron thermal transport in these discharges remains unclear, leading to considerable uncertainty when extrapolating to future spherical tokamak (ST) devices at much lower collisionality. Linear gyrokinetic simulations find microtearing modes to be unstable in high collisionality discharges. First non-linear gyrokinetic simulations of microtearing turbulence in NSTX show they can yield experimental levels of transport. Magnetic flutter is responsible for almost all the transport ({approx}98%), perturbed field line trajectories are globally stochastic, and a test particle stochastic transport model agrees to within 25% of the simulated transport. Most significantly, microtearing transport is predicted to increase with electron collisionality, consistent with the observed NSTX confinement scaling. While this suggests microtearing modes may be the source of electron thermal transport, the predictions are also very sensitive to electron temperature gradient, indicating the scaling of the instability threshold is important. In addition, microtearing turbulence is susceptible to suppression via sheared E Multiplication-Sign B flows as experimental values of E Multiplication-Sign B shear (comparable to the linear growth rates) dramatically reduce the transport below experimental values. Refinements in numerical resolution and physics model assumptions are expected to minimize the apparent discrepancy. In cases where the predicted transport is strong, calculations suggest that a proposed polarimetry diagnostic may be sensitive to the magnetic perturbations associated with the unique structure of microtearing turbulence.
New Capabilities and Results for the National Spherical Torus Experiment
M.G. Bell, R.E. Bell, D.A. Gates, S.M. Kaye, H. Kugel, B.P. LeBlanc, F.M. Levinton, R. Maingi, J.E. Menard, R. Raman, S.A. Sabbagh, D. Stutman and the NSTX Research Team
2008-02-29
The National Spherical Torus Experiment (NSTX) produces plasmas with toroidal aspect ratio as low as 1.25, which can be heated by up to 6 MW High-Harmonic Fast Waves and up to 7 MW of deuterium Neutral Beam Injection. Using new poloidal fields coils, plasmas with cross-section elongation up to 2.7, triangularity 0.8, plasma currents Ip up to 1.5 MA and normalized currents Ip/a?BT up to 7.5 MA/m?T have been achieved. A significant extension of the plasma pulse length, to 1.5 s at a plasma current of 0.7 MA, has been achieved by exploiting the bootstrap and NBI-driven currents to reduce the dissipation of poloidal flux. Inductive plasma startup has been supplemented by Coaxial Helicity Injection (CHI) and the production of persistent current on closed flux surfaces by CHI has now been demonstrated in NSTX. The plasma response to magnetic field perturbations with toroidal mode numbers n = 1 or 3 and the effects on the plasma rotation have been investigated using three pairs of coils outside the vacuum vessel. Recent studies of both MHD stability and of transport benefitted from improved diagnostics, including measurements of the internal poloidal field using the motional Stark effect (MSE). In plasmas with a region of reversed magnetic shear in the core, now confirmed by the MSE data, improved electron confinement has been observed.
Electron Bernstein Wave Research on the National Spherical Torus Experiment
G. Taylor; A. Bers; T.S. Bigelow; M.D. Carter; J.B. Caughman; J. Decker; S. Diem; P.C. Efthimion; N.M. Ershov; E. Fredd; R.W. Harvey; J. Hosea; F. Jaeger; J. Preinhaelter; A.K. Ram; D.A. Rasmussen; A.P. Smirnov; J.B. Wilgen; J.R. Wilson
2005-04-21
Off-axis electron Bernstein wave current drive (EBWCD) may be critical for sustaining noninductive high-beta National Spherical Torus Experiment (NSTX) plasmas. Numerical modeling results predict that the {approx}100 kA of off-axis current needed to stabilize a solenoid-free high-beta NSTX plasma could be generated via Ohkawa current drive with 3 MW of 28 GHz EBW power. In addition, synergy between EBWCD and bootstrap current may result in a 10% enhancement in current-drive efficiency with 4 MW of EBW power. Recent dual-polarization EBW radiometry measurements on NSTX confirm that efficient coupling to EBWs can be readily accomplished by launching elliptically polarized electromagnetic waves oblique to the confining magnetic field, in agreement with numerical modeling. Plans are being developed for implementing a 1 MW, 28 GHz proof-of-principle EBWCD system on NSTX to test the EBW coupling, heating and current-drive physics at high radio-frequency power densities.
Status of the control system on the National Spherical Torus Experiment (NSTX)
Princeton Plasma Physics Laboratory
#61 final Status of the control system on the National Spherical Torus Experiment (NSTX) D. A Abstract In 2003, the NSTX plasma control system was used for plasma shape control using real. More recently, the system has been upgraded to support feedback control of the resistive wall mode (RWM
Fast ion absorption of the high harmonic fast wave in the National Spherical Torus Experiment a...
Egedal, Jan
above the beam injection energy is sustained by the wave. In agreement with modeling, these experimentsFast ion absorption of the high harmonic fast wave in the National Spherical Torus Experiment a Institute of Technology, Cambridge, Massachusetts 02139 #Received 23 October 2003; accepted 19 December 2003
Fast ion absorption of the high harmonic fast wave in the National Spherical Torus Experimenta...
injection energy is sustained by the wave. In agreement with modeling, these experiments find the rfFast ion absorption of the high harmonic fast wave in the National Spherical Torus Experimenta... A Institute of Technology, Cambridge, Massachusetts 02139 Received 23 October 2003; accepted 19 December 2003
Spherical torus fusion reactor
Peng, Yueng-Kay M. (Oak Ridge, TN)
1989-01-01
A fusion reactor is provided having a near spherical-shaped plasma with a modest central opening through which straight segments of toroidal field coils extend that carry electrical current for generating a toroidal magnet plasma confinement fields. By retaining only the indispensable components inboard of the plasma torus, principally the cooled toroidal field conductors and in some cases a vacuum containment vessel wall, the fusion reactor features an exceptionally small aspect ratio (typically about 1.5), a naturally elongated plasma cross section without extensive field shaping, requires low strength magnetic containment fields, small size and high beta. These features combine to produce a spherical torus plasma in a unique physics regime which permits compact fusion at low field and modest cost.
Imaging x-ray crystal spectrometers for the National Spherical Torus Experiment
Bitter, M.; Hill, K.W.; Roquemore, A.L.; Beiersdorfer, P.; Kahn, S.M.; Elliott, S.R.; Fraenkel, B.
1999-01-01
A new type of high-resolution x-ray imaging crystal spectrometers is described for implementation on the National Spherical Torus Experiment (NSTX) to provide spatially and temporally resolved data on the ion temperature, toroidal and poloidal plasma rotation, electron temperature, impurity ion-charge state distributions, and impurity transport. These data are derived from observations of the satellite spectra of heliumlike argon, ArthinspXVII, which is the dominant charge state for electron temperatures in the range from 0.4 to 3.0 keV and which is accessible to NSTX. Experiments at the Torus Experiment for Technology Oriented Research (TEXTOR) demonstrate that a throughput of 2{times}10{sup 5}thinspphotons/s (corresponding to the count-rate limit of the present detectors) can easily be obtained with small, nonperturbing argon gas puffs of less than 1{times}10{sup {minus}3}thinspTorrthinspscr(l)/s, so that it is possible to record spectra with a small statistical error and a good time resolution (typically 50 and 1 ms in some cases). Employing a novel design, which is based on the imaging properties of spherically bent crystals, the spectrometers will provide spectrally and spatially resolved images of the plasma for all experimental conditions, which include ohmically heated discharges as well as plasmas with rf and neutral-beam heating. The conceptual design, experimental results on the focusing properties, and relevant spectral data from TEXTOR are presented. {copyright} {ital 1999 American Institute of Physics.}
Jaworski, M A; Gray, T K; Kaita, R; Kallman, J; Kugel, H; LeBlanc, B; McLean, A; Sabbagh, S A; Soukanovskii, V; Stotler, D P
2011-06-03
The National Spherical Torus Experiment (NSTX) has recently studied the use of a liquid lithium divertor (LLD). Divertor Langmuir probes have also been installed for making measurements of the local plasma conditions. A non-local probe interpretation method is used to supplement the classical probe interpretation and obtain measurements of the electron energy distribution function (EEDF) which show the occurrence of a hot-electron component. Analysis is made of two discharges within a sequence that exhibited changes in plasma fueling efficiency. It is found that the local electron temperature increases and that this increase is most strongly correlated with the energy contained within the hot-electron population. Preliminary interpretative modeling indicates that kinetic effects are likely in the NSTX.
Divertor Heat Flux Mitigation in High-Performance H-mode Plasmas in the National Spherical Torus
Princeton Plasma Physics Laboratory
magnetic flux expansion and partial detachment of the outer strike point at several D2 injection rates of acceptable divertor plate material erosion rates and heat fluxes to q 10 MW/m2 , a limit imposedDivertor Heat Flux Mitigation in High-Performance H-mode Plasmas in the National Spherical Torus
Approval of CD-2 for the National Spherical Torus Experiment (NSTX) Upgrade Project
Princeton Plasma Physics Laboratory
of compact and high normalized pressure "spherical torus" (ST) magnetic fusion plasmas. The compact Plasma Physics Laboratory DOE Princeton Site Office (SSO) Office of Science Office of Fusion Energy Selection and Cost Range for the NSTX Upgrade Project was approved by the Associate Director for Fusion
Direct X-B mode conversion for high-? national spherical torus experiment in nonlinear regime
Ali Asgarian, M. E-mail: maa@msu.edu; Parvazian, A.; Abbasi, M.; Verboncoeur, J. P.
2014-09-15
Electron Bernstein wave (EBW) can be effective for heating and driving currents in spherical tokamak plasmas. Power can be coupled to EBW via mode conversion of the extraordinary (X) mode wave. The most common and successful approach to study the conditions for optimized mode conversion to EBW was evaluated analytically and numerically using a cold plasma model and an approximate kinetic model. The major drawback in using radio frequency waves was the lack of continuous wave sources at very high frequencies (above the electron plasma frequency), which has been addressed. A future milestone is to approach high power regime, where the nonlinear effects become significant, exceeding the limits of validity for present linear theory. Therefore, one appropriate tool would be particle in cell (PIC) simulation. The PIC method retains most of the nonlinear physics without approximations. In this work, we study the direct X-B mode conversion process stages using PIC method for incident wave frequency f{sub 0}?=?15?GHz, and maximum amplitude E{sub 0}?=?10{sup 5?}V/m in the national spherical torus experiment (NSTX). The modelling shows a considerable reduction in X-B mode conversion efficiency, C{sub modelling}?=?0.43, due to the presence of nonlinearities. Comparison of system properties to the linear state reveals predominant nonlinear effects; EBW wavelength and group velocity in comparison with linear regime exhibit an increment around ?36% and 17%, respectively.
Spherical torus fusion reactor
Martin Peng, Y.K.M.
1985-10-03
The object of this invention is to provide a compact torus fusion reactor with dramatic simplification of plasma confinement design. Another object of this invention is to provide a compact torus fusion reactor with low magnetic field and small aspect ratio stable plasma confinement. In accordance with the principles of this invention there is provided a compact toroidal-type plasma confinement fusion reactor in which only the indispensable components inboard of a tokamak type of plasma confinement region, mainly a current conducting medium which carries electrical current for producing a toroidal magnet confinement field about the toroidal plasma region, are retained.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Gerhardt, S. P.; Fredrickson, E.; Guttadora, L.; Kaita, R.; Kugel, H.; Menard, J.; Takahashi, H.
2011-10-06
This paper describes techniques for measuring halo currents, and their associated toroidal peaking, in the National Spherical Torus Experiments. The measurements are based on three techniques: (i) measurement of the toroidal field created by the poloidal halo current, either with segmented Rogowski coils or discrete toroidal field sensors, (ii) the direct measurement of halo currents into specially instrument tiles, and (iii) small Rogowski coils placed on the mechanical supports of in-vessel components. For the segmented Rogowski coils and discrete toroidal field detectors, it is shown that the toroidal peaking factor inferred from the data is significantly less than the peakingmore »factor of the underlying halo current distribution, and a simple model is developed to relate the two. For the array of discrete toroidal field detectors and small Rogowski sensors, the compensation steps that are used to isolate the halo current signal are described. The electrical and mechanical design of compact under-tile resistive shunts and mini-Rogowski coils is described. Example data from the various systems is shown.« less
Liu, D., E-mail: deyongl@uci.edu; Heidbrink, W. W.; Zhu, Y. B. [Department of Physics and Astronomy, University of California - Irvine, Irvine, California 92697 (United States); Tritz, K. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Roquemore, A. L.; Medley, S. S. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
2014-11-15
A new compact, multi-channel Solid State Neutral Particle Analyzer (SSNPA) diagnostic based on silicon photodiode array has been designed and is being fabricated for the National Spherical Torus Experiment-Upgrade (NSTX-U). The SSNPA system utilizes a set of vertically stacked photodiode arrays in current mode viewing the same plasma region with different filter thickness to obtain fast temporal resolution (?120 kHz bandwidth) and coarse energy information in three bands of >25?keV, >45 keV, and >65 keV. The SSNPA system consists of 15 radial sightlines that intersect existing on-axis neutral beams at major radii between 90 and 130 cm, 15 tangential sightlines that intersect new off-axis neutral beams at major radii between 120 and 145 cm. These two subsystems aim at separating the response of passing and trapped fast ions. In addition, one photodiode array whose viewing area does not intersect any neutral beams is used to monitor passive signals produced by fast ions that charge exchange with background neutrals.
Gerhardt, S. P.; Fredrickson, E.; Guttadora, L.; Kaita, R.; Kugel, H.; Menard, J. [Princeton Plasma Physics Laboratory, Plainsboro, New Jersey 08540 (United States); Takahashi, H. [Princeton Fusion Research LLC, Princeton, New Jersey 08540 (United States)
2011-10-15
This paper describes techniques for measuring halo currents, and their associated toroidal peaking, in the National Spherical Torus Experiments [M. Ono et al., Nucl. Fusion 40, 557 (2000)]. The measurements are based on three techniques: (1) measurement of the toroidal field created by the poloidal halo current, either with segmented Rogowski coils or discrete toroidal field sensors, (2) the direct measurement of halo currents into specially instrument tiles, and (3) small Rogowski coils placed on the mechanical supports of in-vessel components. For the segmented Rogowski coils and discrete toroidal field detectors, it is shown that the toroidal peaking factor inferred from the data is significantly less than the peaking factor of the underlying halo current distribution, and a simple model is developed to relate the two. For the array of discrete toroidal field detectors and small Rogowski sensors, the compensation steps that are used to isolate the halo current signal are described. The electrical and mechanical design of compact under-tile resistive shunts and mini-Rogowski coils is described. Example data from the various systems are shown.
Status and Plans for the National Spherical Torus Experimental Research Facility
M. Ono; M.G. Bell; R.E. Bell; J.M. Bialek; T. Bigelow; M. Bitter; plus 148 additional authors
2005-07-27
An overview of the research capabilities and the future plans on the MA-class National Spherical Torus Experiment (NSTX) at Princeton is presented. NSTX research is exploring the scientific benefits of modifying the field line structure from that in more conventional aspect ratio devices, such as the tokamak. The relevant scientific issues pursued on NSTX include energy confinement, MHD stability at high beta, non-inductive sustainment, solenoid-free start-up, and power and particle handling. In support of the NSTX research goal, research tools are being developed by the NSTX team. In the context of the fusion energy development path being formulated in the US, an ST-based Component Test Facility (CTF) and, ultimately a high beta Demo device based on the ST, are being considered. For these, it is essential to develop high performance (high beta and high confinement), steady-state (non-inductively driven) ST operational scenarios and an efficient solenoid-free start-up concept. We will also briefly describe the Next-Step-ST (NSST) device being designed to address these issues in fusion-relevant plasma conditions.
A Megawatt-level 28z GHz Heating System For The National Spherical Torus Experiment Upgrade
Taylor, Gary
2014-04-01
The National Spherical Torus Experiment Upgrade (NSTX-U) will operate at axial toroidal fields of < 1 T and plasma currents, Ip < 2 MA. The development of non-inductive (NI) plasmas is a major long-term research goal for NSTX-U. Time dependent numerical simulations of 28 GHz electron cyclotron (EC) heating of low density NI start-up plasmas generated by Coaxial Helicity Injection (CHI) in NSTX-U predict a significant and rapid increase of the central electron temperature (Te(0)) before the plasma becomes overdense. The increased Te(0) will significantly reduce the Ip decay rate of CHI plasmas, allowing the coupling of fast wave heating and neutral beam injection. A megawatt-level, 28 GHz electron heating system is planned for heating NI start-up plasmas in NSTX-U. In addition to EC heating of CHI start-up discharges, this system will be used for electron Bernstein wave (EBW) plasma start-up, and eventually for EBW heating and current drive during the Ip flattop.
Recent Progress on Spherical Torus Research
Ono, Masayuki; Kaita, Robert
2014-01-01
The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio (A = R0/a) reduced to A ~ 1.5, well below the normal tokamak operating range of A ? 2.5. As the aspect ratio is reduced, the ideal tokamak beta ? (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as ? ~ 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural elongation ?, which makes its plasma shape appear spherical, the ST configuration can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to its longer term goal of attractive fusion energy power source. Since the start of the two megaampere class ST facilities in 2000, National Spherical Torus Experiment (NSTX) in the US and Mega Ampere Spherical Tokamak (MAST) in UK, active ST research has been conducted worldwide. More than sixteen ST research facilities operating during this period have achieved remarkable advances in all of fusion science areas, involving fundamental fusion energy science as well as innovation. These results suggest exciting future prospects for ST research both near term and longer term. The present paper reviews the scientific progress made by the worldwide ST research community during this new mega-ampere-ST era.
Bell, R E; Kaye, S M; Kolesnikov, R A; LeBlance, B P; Rewolldt, G; Wang, W X
2010-04-07
Knowledge of poloidal velocity is necessary for the determination of the radial electric field, Er, which along with its gradient is linked to turbulence suppression and transport barrier formation. Recent measurements of poloidal flow on conventional tokamaks have been reported to be an order of magnitude larger than expected from neoclassical theory. In contrast, recent poloidal velocity measurements on the NSTX spherical torus [S. M. Kaye et al., Phys. Plasmas 8, 1977 (2001)] are near or below neoclassical estimates. A novel charge exchange recombination spectroscopy diagnostic is used, which features active and passive sets of up/down symmetric views to produce line-integrated poloidal velocity measurements that do not need atomic physics corrections. Local profiles are obtained with an inversion. Poloidal velocity measurements are compared with neoclassical values computed with the codes NCLASS [W. A. Houlberg et al., Phys. Plasmas 4, 3230 (1997)] and GTC-Neo [W. X. Wang, et al., Phys. Plasmas 13, 082501 (2006)], which has been updated to handle impurities. __________________________________________________
Princeton Plasma Physics Laboratory
A dual wavelength imaging system for plasma-surface interaction studies on the National Spherical.), quantitative analysis of emission from impurity or fuel atoms (e.g., in DIII- D10 , NSTX11 , etc.), real
Princeton Plasma Physics Laboratory
Demonstration of Tokamak Ohmic Flux Saving by Transient Coaxial Helicity Injection in the National in a significant Ohmic flux saving and produced equivalent quality tokamak plasmas. In addition, for the first time
Wang, Feng; Liu, J. Y. [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China); Fu, G. Y.; Breslau, J. A. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Tritz, Kevin [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)] [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)
2013-07-15
Plasmas in spherical and conventional tokamaks, with weakly reversed shear q profile and minimum q above but close to unity, are susceptible to an non-resonant (m,n) = (1,1) internal kink mode. This mode can saturate and persist and can induce a (2,1) seed island for Neoclassical Tearing Mode. [Breslau et al. Nucl. Fusion 51, 063027 (2011)]. The mode can also lead to large energetic particle transport and significant broadening of beam-driven current. Motivated by these important effects, we have carried out extensive nonlinear simulations of the mode with finite toroidal rotation using parameters and profiles of an NTSX plasma with a weakly reversed shear profile. The numerical results show that, at the experimental level, plasma rotation has little effect on either equilibrium or linear stability. However, rotation can significantly influence the nonlinear dynamics of the (1,1) mode and the induced (2,1) magnetic island. The simulation results show that a rotating helical equilibrium is formed and maintained in the nonlinear phase at finite plasma rotation. In contrast, for non-rotating cases, the nonlinear evolution exhibits dynamic oscillations between a quasi-2D state and a helical state. Furthermore, the effects of rotation are found to greatly suppress the (2,1) magnetic island even at a low level.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Sechrest, Y.; Munsat, T.; D’Ippolito, D. A.; Maqueda, R. J.; Myra, J. R.; Russell, D.; Zweben, S. J.
2011-01-01
Fluctuations in the edge and scrape-off layer (SOL) of L-mode plasmas in the National Spherical Torus Experiment (NSTX) as observed by the gas puff imaging (GPI) diagnostic are studied. Calculation of local, time resolved velocity maps using the Hybrid Optical Flow and Pattern Matching Velocimetry (HOP-V) code enables analysis of turbulent flow and shear behavior. Periodic reversals in the direction of the poloidal flow near the separatrix are observed. Also, poloidal velocities and their radial shearing rate are found to be well correlated with the fraction of D? light contained in the SOL, which acts as a measure of turbulentmore »bursts. The spectra of GPI intensity and poloidal velocity both have a strong feature near 3 kHz, which appears to correspond with turbulent bursts. This mode exhibits a poloidal structure with poloidal wavenumber of 7.7 m-1 for GPI intensity and 3.4 m-1 for poloidal velocity, and the poloidal velocity fluctuations near 3 kHz remain coherent over length scales in excess of the turbulent scales. Furthermore, recent SOL Turbulence (SOLT) simulations find a parameter regime that exhibits periodic bursty transport and shares many qualitative similarities with the experimental data. Strong correlations between the shearing rate and the turbulent bursts are observed for time periods of ~ 2 ms, but the relationship is complicated by several factors. Finally, measurements of the radial profiles of the Reynolds shear stresses are reported. These radial profiles exhibit many similarities for several shots, and a region with positive radial gradient is seen to be coincident with local flow shear.« less
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Sechrest, Y. [Univ. of Colorado, Boulder, CO (United States); Munsat, T. [Univ. of Colorado, Boulder, CO (United States); D’Ippolito, D. A. [Lodestar Research Corp., Boulder, CO (United States); Maqueda, R. J. [Princeton Plasma Physics Lab., NJ (United States); Myra, J. R. [Lodestar Research Corp., Boulder, CO (United States); Russell, D. [Lodestar Research Corp., Boulder, CO (United States); Zweben, S. J. [Princeton Plasma Physics Lab., NJ (United States)
2011-01-10
Fluctuations in the edge and scrape-off layer (SOL) of L-mode plasmas in the National Spherical Torus Experiment (NSTX) [S. M. Kaye et al.,Phys. Plasmas 8, 1977 (2001)] as observed by the gas puff imaging (GPI) diagnostic are studied. Calculation of local, time resolved velocity maps using the Hybrid Optical Flow and Pattern Matching Velocimetry (HOP-V) code enables analysis of turbulent flow and shear behavior. Periodic reversals in the direction of the poloidal flow near the separatrix are observed. Also, poloidal velocities and their radial shearing rate are found to be well correlated with the fraction of D? light contained in the SOL, which acts as a measure of turbulent bursts. The spectra of GPI intensity and poloidal velocity both have a strong feature near 3 kHz, which appears to correspond with turbulent bursts. This mode exhibits a poloidal structure with poloidal wavenumber of 7.7 m-1 for GPI intensity and 3.4 m-1 for poloidal velocity, and the poloidal velocity fluctuations near 3 kHz remain coherent over length scales in excess of the turbulent scales. Furthermore, recent SOL Turbulence (SOLT) simulations find a parameter regime that exhibits periodic bursty transport and shares many qualitative similarities with the experimental data. Strong correlations between the shearing rate and the turbulent bursts are observed for time periods of ~ 2 ms, but the relationship is complicated by several factors. Finally, measurements of the radial profiles of the Reynolds shear stresses are reported. These radial profiles exhibit many similarities for several shots, and a region with positive radial gradient is seen to be coincident with local flow shear.
Progress Towards High Performance, Steady-state Spherical Torus
M. Ono; M.G. Bell; R.E. Bell; T. Bigelow; M. Bitter; W. Blanchard; J. Boedo; C. Bourdelle; C. Bush; W. Choe; J. Chrzanowski; D.S. Darrow; S.J. Diem; R. Doerner; P.C. Efthimion; J.R. Ferron; R.J. Fonck; E.D. Fredrickson; G.D. Garstka; D.A. Gates; T. Gray; L.R. Grisham; W. Heidbrink; K.W. Hill; D. Hoffman; T.R. Jarboe; D.W. Johnson; R. Kaita; S.M. Kaye; C. Kessel; J.H. Kim; M.W. Kissick; S. Kubota; H.W. Kugel; B.P. LeBlanc; K. Lee; S.G. Lee; B.T. Lewicki; S. Luckhardt; R. Maingi; R. Majeski; J. Manickam; R. Maqueda; T.K. Mau; E. Mazzucato; S.S. Medley; J. Menard; D. Mueller; B.A. Nelson; C. Neumeyer; N. Nishino; C.N. Ostrander; D. Pacella; F. Paoletti; H.K. Park; W. Park; S.F. Paul; Y.-K. M. Peng; C.K. Phillips; R. Pinsker; P.H. Probert; S. Ramakrishnan; R. Raman; M. Redi; A.L. Roquemore; A. Rosenberg; P.M. Ryan; S.A. Sabbagh; M. Schaffer; R.J. Schooff; R. Seraydarian; C.H. Skinner; A.C. Sontag; V. Soukhanovskii; J. Spaleta; T. Stevenson; D. Stutman; D.W. Swain; E. Synakowski; Y. Takase; X. Tang; G. Taylor; J. Timberlake; K.L. Tritz; E.A. Unterberg; A. Von Halle; J. Wilgen; M. Williams; J.R. Wilson; X. Xu; S.J. Zweben; R. Akers; R.E. Barry; P. Beiersdorfer; J.M. Bialek; B. Blagojevic; P.T. Bonoli; M.D. Carter; W. Davis; B. Deng; L. Dudek; J. Egedal; R. Ellis; M. Finkenthal; J. Foley; E. Fredd; A. Glasser; T. Gibney; M. Gilmore; R.J. Goldston; R.E. Hatcher; R.J. Hawryluk; W. Houlberg; R. Harvey; S.C. Jardin; J.C. Hosea; H. Ji; M. Kalish; J. Lowrance; L.L. Lao; F.M. Levinton; N.C. Luhmann; R. Marsala; D. Mastravito; M.M. Menon; O. Mitarai; M. Nagata; G. Oliaro; R. Parsells; T. Peebles; B. Peneflor; D. Piglowski; G.D. Porter; A.K. Ram; M. Rensink; G. Rewoldt; P. Roney; K. Shaing; S. Shiraiwa; P. Sichta; D. Stotler; B.C. Stratton; R. Vero; W.R. Wampler; G.A. Wurden
2003-10-02
Research on the Spherical Torus (or Spherical Tokamak) is being pursued to explore the scientific benefits of modifying the field line structure from that in more moderate aspect-ratio devices, such as the conventional tokamak. The Spherical Tours (ST) experiments are being conducted in various U.S. research facilities including the MA-class National Spherical Torus Experiment (NSTX) at Princeton, and three medium-size ST research facilities: Pegasus at University of Wisconsin, HIT-II at University of Washington, and CDX-U at Princeton. In the context of the fusion energy development path being formulated in the U.S., an ST-based Component Test Facility (CTF) and, ultimately a Demo device, are being discussed. For these, it is essential to develop high-performance, steady-state operational scenarios. The relevant scientific issues are energy confinement, MHD stability at high beta (B), noninductive sustainment, ohmic-solenoid-free start-up, and power and particle handling. In the confinement area, the NSTX experiments have shown that the confinement can be up to 50% better than the ITER-98-pby2 H-mode scaling, consistent with the requirements for an ST-based CTF and Demo. In NSTX, CTF-relevant average toroidal beta values bT of up to 35% with the near unity central betaT have been obtained. NSTX will be exploring advanced regimes where bT up to 40% can be sustained through active stabilization of resistive wall modes. To date, the most successful technique for noninductive sustainment in NSTX is the high beta-poloidal regime, where discharges with a high noninductive fraction ({approx}60% bootstrap current + neutral-beam-injected current drive) were sustained over the resistive skin time. Research on radio-frequency-based heating and current drive utilizing HHFW (High Harmonic Fast Wave) and EBW (Electron Bernstein Wave) is also pursued on NSTX, Pegasus, and CDX-U. For noninductive start-up, the Coaxial Helicity Injection (CHI), developed in HIT/HIT-II, has been adopted on NSTX to test the method up to Ip {approx} 500 kA. In parallel, start-up using radio-frequency current drive and only external poloidal field coils are being developed on NSTX. The area of power and particle handling is expected to be challenging because of the higher power density expected in the ST relative to that in conventional aspect-ratio tokamaks. Due to its promise for power and particle handling, liquid lithium is being studied in CDX-U as a potential plasma-facing surface for a fusion reactor.
Abs t rac t ---The National Spherical Torus Experiment (NSTX) is a low aspect ratio s ph e r i c a l
, and initial power tests were completed in February o f 1 9 9 9 . The majority of the design and c on s t r u c. The Centerstack Assembly consists of the i nn e r legs of the Toroidal Field (TF) windings, t h e Ohmic Heating issues associated with the design, fabrication and assembly of the NSTX Torus system i nc l ud i ng those
An Inexpensive Ohmic Transformer Firing Circuit for the CDXU Spherical Torus
1 An Inexpensive Ohmic Transformer Firing Circuit for the CDXÂU Spherical Torus T. Munsat, R designed and modeled a simple, efficient circuit for delivering power to the CDXÂU ohmic transformer, spherical tori) have traditionally driven plasma current by using the transformer action of a centrally
An Inexpensive Ohmic Transformer Firing Circuit for the CDX-U Spherical Torus
1 An Inexpensive Ohmic Transformer Firing Circuit for the CDX-U Spherical Torus T. Munsat, R designed and modeled a simple, efficient circuit for delivering power to the CDX-U ohmic transformer, spherical tori) have traditionally driven plasma current by using the transformer action of a centrally
Review Closeout for the National Spherical Torus
Princeton Plasma Physics Laboratory
Barry Sullivan, DOE/SC Tony Indelicato, DOE/PSO Maria Dikeakos, DOE/PSO #12;OFFICE OF SCIENCE 3 Charge
Supported by National Spherical Torus Experiment
Transport? - Jenko, Doland,Hammet, PoP 8, 2001 JHU ETG's Role in ELM induced Cold Pulse S = - 0.3 kre ~ 0 Scaling, Electron Transport · Full set of diagnostics: including MSE for j(r) Unique Energetic Particle control coils on feedback performance #12;Significant Progress on Electron Heat Transport Physics
Physics basis for a spherical torus power plant S.C. Jardin a,
Najmabadi, Farrokh
Physics basis for a spherical torus power plant S.C. Jardin a, *, C.E. Kessel a , J. Menard a , T for a fusion power plant. A special class of wall-stabilized high-b high-bootstrap fraction low-aspect-ratio tokamak; Fusion power plant; Plasma operating regime 1. Introduction The most significant difference
Spherical Torus Plasma Interactions with Large-Area Liquid Lithium Surfaces in CDX-U
California at Los Angeles, University of
Outside of Plasma" (DOLLOP) lithium wall conditioning experiments,[3] for example, in the Tokamak Fusion, introduction of large area lithium limiter targets and walls into existing tokamak facilities has not yet taken- 1 - Spherical Torus Plasma Interactions with Large-Area Liquid Lithium Surfaces in CDX-U R. KAITA
558: Calculation of Eddy Currents in the ETE Spherical Torus G.O. Ludwig
558: Calculation of Eddy Currents in the ETE Spherical Torus G.O. Ludwig Instituto Nacional de model based on the Green's function method. The distribution of eddy currents is calculated using a thin well with values of the eddy currents measured in ETE. INTRODUCTION This paper presents a magnetostatic
Washington at Seattle, University of
-Torus-Like Field-Reversed Configuration H. Y. Guo, A. L. Hoffman, L. C. Steinhauer, and K. E. Miller Redmond Plasma (FRC) with a spherical- torus- (ST-)like core is produced in the translation, confinement. This plasma state exhibits a remarkable stabilizing property for the ubiquitous n 2 centrifugally driven
Berkery, J. W.; Sabbagh, S. A.; Balbaky, A.; Bell, R. E.; Diallo, A.; Gerhardt, S. P.; LeBlanc, B. P.; Manickam, J.; Menard, J. E.; Podestà, M.; Betti, R.
2014-05-15
Global mode stability is studied in high-? National Spherical Torus Experiment (NSTX) plasmas to avoid disruptions. Dedicated experiments in NSTX using low frequency active magnetohydrodynamic spectroscopy of applied rotating n?=?1 magnetic fields revealed key dependencies of stability on plasma parameters. Observations from previous NSTX resistive wall mode (RWM) active control experiments and the wider NSTX disruption database indicated that the highest ?{sub N} plasmas were not the least stable. Significantly, here, stability was measured to increase at ?{sub N}?l{sub i} higher than the point where disruptions were found. This favorable behavior is shown to correlate with kinetic stability rotational resonances, and an experimentally determined range of measured E?×?B frequency with improved stability is identified. Stable plasmas appear to benefit further from reduced collisionality, in agreement with expectation from kinetic RWM stabilization theory, but low collisionality plasmas are also susceptible to sudden instability when kinetic profiles change.
National Spherical Torus Experiment NSTX CENTER STACK UPGRADE
Princeton Plasma Physics Laboratory
; added section 2.6 "Design Criteria"; added 3.1.3.3 "Center Stack Assembly"; 3.1.3.4 "Coil Bus Runs 2.5 Field Errors 14 2.6 Design Criteria 14 2.6.1 General Design Guidelines 14 2.6.2 Failure Modes and Effects Analysis (FMEA) 15 2.6.3 Structural Design Criteria 15 2.7 Material
National Spherical Torus Experiment NSTX CENTER STACK UPGRADE
Princeton Plasma Physics Laboratory
Analysis (FMEA) 14 2.6.3 Structural Design Criteria 15 2.7 Material Selection 15 2.8 General Electrical
National Spherical Torus Experiment Upgrade Status and Plans*
KAIST POSTECH Seoul Natl U ASIPP CIEMAT FOM Inst DIFFER ENEA, Frascati CEA, Cadarache IPP, Jülich IPP
National Spherical Torus Experiment (NSTX) Power Supply Real Time Controller
. The NSTX depends on a real time, high speed, synchronous, and deterministic control system isolated from each other but subject to the same "Firing Generator" (FG). Each PSS Magnets Power Supply
National Spherical Torus Experiment (NSTX) Power Supply Real Time Controller
depends on a real time, high speed, synchronous, and deterministic control system acting on a system Generator" (FG). Each PSS Magnets Power Supply System Plasma Power Supply Real Time Control Plasma Real Time
M. Ono, NSTX 1 National Spherical Torus Experiment (NSTX)*
. The NBI heating system and associated NBI based diagnostics such as the CHERS will be operational in Oct.5, and plasma pulse length of up to 5 sec. The plasma heating / current drive (CD) tools are High Harmonic Fast device is shown in Fig. 1. The device midplane is about 3.5 m from the floor. The device center
PPPL-3445 PPPL-3445 National Spherical Torus Experiment (NSTX)
in Calendar Year 2000. The home page for PPPL Reports and Publications is: http://www.pppl.gov/pub_report/ DOE-term applications such as the Volume Neutron Source (VNS) and burning plasmas, and future applications to the plasma. The NBI heating system and associated NBI based diagnostics such as the CHERS will be operational
CONSTRUCTING THE NATIONAL Spherical Torus Experiment Upgrade took
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Midplane neutral density profiles in the National Spherical Torus
Office of Scientific and Technical Information (OSTI)
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National Spherical Torus Experiment (NSTX) | Princeton Plasma Physics Lab
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Choe, Kyumin; Jung, Bongki; Chung, Kyoung-Jae; Hwang, Y. S.; Center for Advance Research in Fusion Reactor Engineering, Seoul National University, Seoul 151-744
2014-02-15
Despite of high plasma density, helicon plasma has not yet been applied to a large area ion source such as a driver for neutral beam injection (NBI) system due to intrinsically poor plasma uniformity in the discharge region. In this study, a radio-frequency (RF) ion source with multi-helicon plasma injectors for high plasma density with good uniformity has been designed and constructed for the NBI system of Versatile Experiment Spherical Torus at Seoul National University. The ion source consists of a rectangular plasma expansion chamber (120 × 120 × 120 mm{sup 3}), four helicon plasma injectors with annular permanent magnets and RF power system. Main feature of the source is downstream plasma confinement in the cusp magnetic field configuration which is generated by arranging polarities of permanent magnets in the helicon plasma injectors. In this paper, detailed design of the multi-helicon plasma injector and plasma characteristics of the ion source are presented.
Disruptions, Disruptivity, and Safer Operating Windows in the High-? Spherical Torus NSTX
Brown, T; Goldston, R J; El-Guebaly, L; Kessel, C; Neilson, G H; Malang, S; Menard, J E; Prager, S; Scott, S; Titus, P; Waganer, L
2012-09-26
A fusion pilot plant study was initiated to clarify the development needs in moving from ITER to a first of a kind fusion power plant. The mission of the pilot plant was set to encompass component test and fusion nuclear science missions yet produce net electricity with high availability in a device designed to be prototypical of the commercial device. The objective of the study was to evaluate three different magnetic configuration options, the advanced tokamak (AT), spherical tokamak (ST) and compact stellarator (CS) in an effort to establish component characteristics, maintenance features and the general arrangement of each candidate device. With the move to look beyond ITER the fusion community is now beginning to embark on DEMO reactor studies with an emphasis on defining configuration arrangements that can meet a high availability goal. This paper reviews the AT pilot plant design, detailing the selected maintenance approach, the device arrangement and sizing of the in-vessel components. Details of interfacing auxiliary systems and services that impact the ability to achieve high availability operations will also be discussed.
(NCT) activity: Create a lowered-risk, reduced-cost approach to a fusion environment beyond the ITER Panel Hillis, Don Experimental collaboration ORNL Jarboe, Tom Innovative confinement concepts, startup U Wash Kotschenreuther, Mike Turbulence theory, innovative divertors UT-Austin Mauel, Mike Levitated
Vessel Eddy Current Measurement for the National Spherical Torus Experiment (NSTX)
D.A. Gates; J. Menard; R. Marsala
2004-11-19
A simple analog circuit that measures the NSTX axisymmetric eddy current distribution has been designed and constructed. It is based on simple circuit model of the NSTX vacuum vessel that was calibrated using a special axisymmetric eddy current code which was written so that accuracy was maintained in the vicinity of the current filaments. The measurement and the model have been benchmarked against data from numerous vacuum shots and they are in excellent agreement. This is an important measurement that helps give more accurate equilibrium reconstructions.
Hammett, Greg
of Physics. Related Articles Hybrid-like 2/1 flux-pumping and magnetic island evolution due to edge localized in the presence of suffi- cient E Â B shear,14 which occurs in strongly beam heated plasmas. However
Closeout Report for theCloseout Report for the National Spherical Torus
Princeton Plasma Physics Laboratory
October 27, 2011 Stephen W. Meador, Chairperson DOE/SC Review CommitteeDOE/SC Review Committee Office of Science, U.S. Department of Energy http://www.science.doe.gov/opa/ #12;OFFICE OF SCIENCE Review CommitteeManamy ORNL Ed Synakowski DOE/SCTom McManamy, ORNL Ed Synakowski, DOE/SC Jim Irby, MIT Barry Sullivan, DOE
Department of Energy Review of the National Spherical Torus Experiment (NSTX) Upgrade Project
Princeton Plasma Physics Laboratory
-903-0269 stephen.meador@science.doe.gov Review Committee Subcommittee 1: Technical *Tom McManamy, ORNL 865@fnal.gov Subcommittee 3: Cost and Schedule *Kin Chao, DOE/SC 301-903-4116 kin.chao@science.doe.gov Tim Maier, DOE/BHSO 631-344-2402 tmaier@bnl.gov Darren Morton, DOE/OECM 202-287-1940 darren.morton@hq.doe.gov Mark
National Spherical Torus Experiment (NSTX) | U.S. DOE Office of Science
Office of Science (SC) Website
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Scientific Opportunities and Challenges in the Upgraded National Spherical
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
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La Haye, R. J.; Buttery, R. J. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Gerhardt, S. P. [Princeton Plasma Physics Laboratory, P.O. Box 451 Princeton, New Jersey 08543 (United States); Sabbagh, S. A. [Columbia University, 2960 Broadway, New York, New York 10027-6900 (United States); Brennan, D. P. [University of Tulsa, 800 South Tucker Drive, Tulsa, Oklahoma 74104 (United States)
2012-06-15
Neoclassical tearing mode islands are sustained by helically perturbed bootstrap currents arising at finite beta from toroidal effects that trap a fraction of the particles in non-circulating orbits. DIII-D and NSTX are here operated with similar shape and cross-sectional area but almost a factor of two difference in inverse aspect ratio a/R. In these experiments, destabilized n=1 tearing modes were self-stabilized (reached the 'marginal point') by reducing neutral-beam power and thus beta. The measure of the marginal island gives information on the small-island stabilizing physics that in part (with seeding) governs onset. The marginal island width on NSTX is found to be about three times the ion banana width and agrees with that measured in DIII-D, except for DIII-D modes closer to the magnetic axis, which are about two times the ion banana width. There is a balance of the helically perturbed bootstrap term with small island effects with the sum of the classical and curvature terms in the modified Rutherford equation for tearing-mode stability at the experimental marginal point. Empirical evaluation of this sum indicates that while the stabilizing effect of the curvature term is negligible in DIII-D, it is important in NSTX. The mode temporal behavior from the start of neutral-beam injection reduction also suggests that NSTX operates closer to marginal classical tearing stability; this explains why there is little hysteresis in beta between mode onset, saturation, and self-stabilization (while DIII-D has large hysteresis in beta). NIMROD code module component calculations based on DIII-D and NSTX reconstructed experimental equilibria are used to diagnose and confirm the relative importance of the stabilizing curvature effect, an advantage for low aspect ratio; the relatively greater curvature effect makes for less susceptibility to NTM onset even if the classical tearing stability index is near marginal.
None
2013-08-27
The implementation of the liquid Lithium Divertor (LLD) in NSTX presented a unique opportunity in plasma-material interactions studies. A high density Langmuir Probe (HDLP) array utilizing a dense pack of triple Langmuir probes was built at PPPL and the electronics designed and built by UIUC. It was shown that the HDLP array could be used to characterize the modification of the EEDF during lithium experiments on NSTX as well as characterize the transient particle loads during lithium experiments as a means to study ELMs. With NSTX being upgraded and a new divertor being installed, the HDLP array will not be used in NSTX-U. However UIUC is currently helping to develop two new systems for depositing lithium into NSTX-U, a Liquid Lithium Pellet Dripper (LLPD) for use with the granular injector for ELM mitigation and control studies as well as an Upward-Facing Lithium Evaporator (U-LITER) based on a flash evaporation system using an electron beam. Currently UIUC has Daniel Andruczyk Stationed at PPPL and is developing these systems as well as being involved in preparing the Materials Analysis Particle Probe (MAPP) for use in LTX and NSTX-U. To date the MAPP preparations have been completed. New sample holders were designed by UIUC?s Research Engineer at PPPL and manufactured at PPPL and installed. MAPP is currently being used on LTX to do calibration and initial studies. The LLPD has demonstrated that it can produce pellets. There is still some adjustments needed to control the frequency and particle size. Equipment for the U-LITER has arrived and initial test are being made of the electron beam and design of the U-LITER in progress. It is expected to have these ready for the first run campaign of NSTX-U.
Boedo, J. A. Rudakov, D. L.; Myra, J. R.; D'Ippolito, D. A.; Zweben, S.; Maingi, R.; Maqueda, R. J.; Bell, R.; Kugel, H.; Leblanc, B.; Roquemore, L. A.; Soukhanovskii, V. A.; Ahn, J. W.; Canik, J.; Crocker, N.
2014-04-15
Transport and turbulence profiles were directly evaluated using probes for the first time in the edge and scrape-off layer (SOL) of NSTX [Ono et al., Nucl. Fusion 40, 557 (2000)] in low (L) and high (H) confinement, low power (P{sub in}? 1.3?MW), beam-heated, lower single-null discharges. Radial turbulent particle fluxes peak near the last closed flux surface (LCFS) at ?4×10{sup 21}?s{sup ?1} in L-mode and are suppressed to ?0.2×10{sup 21}?s{sup ?1} in H mode (80%–90% lower) mostly due to a reduction in density fluctuation amplitude and of the phase between density and radial velocity fluctuations. The radial particle fluxes are consistent with particle inventory based on SOLPS fluid modeling. A strong intermittent component is identified. Hot, dense plasma filaments 4–10?cm in diameter, appear first ?2?cm inside the LCFS at a rate of ?1×10{sup 21}?s{sup ?1} and leave that region with radial speeds of ?3–5?km/s, decaying as they travel through the SOL, while voids travel inward toward the core. Profiles of normalized fluctuations feature levels of 10% inside LCFS to ?150% at the LCFS and SOL. Once properly normalized, the intermittency in NSTX falls in similar electrostatic instability regimes as seen in other devices. The L-H transition causes a drop in the intermittent filaments velocity, amplitude and number in the SOL, resulting in reduced outward transport away from the edge and a less dense SOL.
Simulation of High-Harmonic Fast-Wave Heating on the National Spherical Tokamak Experiment
Green, David L [ORNL; Jaeger, Erwin Frederick [ORNL; Chen, Guangye [ORNL; Berry, Lee A [ORNL; Pugmire, Dave [ORNL; Canik, John [ORNL; Ryan, Philip Michael [ORNL
2011-01-01
Images associated with radio-frequency heating of low-confinement mode plasmas in the National Spherical Tokamak Experiment, as calculated by computer simulation, are presented. The AORSA code has been extended to simulate the whole antenna-to-plasma heating system by including both the kinetic physics of the well-confined core plasma and a poorly confined scrape-off plasma and vacuum vessel structure. The images presented show the 3-D electric wave field amplitude for various antenna phasings. Visualization of the simulation results in 3-D makes clear that -30 degrees phasing excites kilo-volt per meter coaxial standing modes in the scrape-off plasma and shows magnetic-field-aligned whispering-gallery type modes localized to the plasma edge.
Spherical Torus (Spherical Tokamak) on the Path to Fusion Energy
USBPO-ITPA activities in preparation for burning plasma research in ITER using physics breadth provided and benefits from USBPO-ITPA in preparing for burning plasma research on ITER "Locked mode" threshold n
Science and Technology of the 10-MA Spherical Tori
Peng, Y-K.M.
1999-11-14
The Spherical Torus (ST) configuration has recently emerged as an example of confinement concept innovation that enables attractive steps in the development of fusion energy. The scientific potential for the ST has been indicated by recent encouraging results from START,2 CDX-U, and HIT. The scientific principles for the D-fueled ST will soon be tested by NSTX (National Spherical Torus Experiment3) in the U.S. and MAST (Mega-Amp Spherical Tokamak4) in the U.K. at the level of l-2 MA in plasma current. More recently, interest has grown in the U.S. in the possibility of near-term ST fusion burn devices at the level of 10 MA in plasma current. The missions for these devices would be to test burning plasma performance in a small, pulsed D-T-fueled ST (i.e., DTST) and to develop fusion energy technologies in a small steady state ST-based Volume Neutron Source (VNS). This paper reports the results of analysis of the key science and technology issues for these devices.
Ding, S.; Kaye, S. M.; Bell, R. E.; Kaita, R.; Kugel, H.; LeBlanc, B. P.; Paul, S.; Wan, B.
2009-10-21
The transport properties of NSTX plasmas obtained during the 2008 experimental cam- paign have been studied and are reported here. Transport trends and dependences have been isolated, and it is found that both electron and ion energy transport coefficients have strong dependences on local values of n?T, which in turn is strongly dependent on local current density profile. Without identifying this dependence, it is difficult to identify others, such as the dependence of transport coefficients on Bp (or q), Ip and Pheat. In addition, a comparison between discharges with and without Lithium wall conditioning has been made. While the trends in the two sets of data are similar, the thermal transport loss, especially in the electron channel, is found to strongly depend on the amount of Lithium deposited, decreasing by up to 50% of its no-Lithium value.
The Condensate from Torus Knots
A. Gorsky; A. Milekhin; N. Sopenko
2015-06-22
We discuss recently formulated instanton-torus knot duality in $\\Omega$-deformed 5D SQED on $\\mathbb{R}^4 \\times S^1$ focusing at the microscopic aspects of the condensate formation in the instanton ensemble. Using the chain of dualities and geometric transitions we embed the SQED with a surface defect into the $SU(2)$ SQCD with $N_f=4$ and identify the numbers $(n,m)$ of the torus $T_{n,m}$ knot as instanton charge and electric charge. The HOMFLY torus knot invariants in the fundamental representation provide entropic factor in the condensate of the massless flavor counting the degeneracy of the instanton--W-boson web with instanton and electric numbers $(n,m)$ but different spin and flavor content. Using the inverse geometrical transition we explain how our approach is related to the evaluation of the HOMFLY invariants in terms of Wilson loop in 3d CS theory. The reduction to 4D theory is briefly considered and some analogy with baryon vertex is conjectured.
Transition between Spherical RFP and Spherical Torus during the Helicity Injection Process
Washington at Seattle, University of
(major radius R = 0.30 m, minor radius a = 0.24 m, aspect ratio #12;22 Gas Puff Valves (4) Insulator, must pass through the m=1/n=1 rational barrier, i.e. the Kruskal-Shafranov limit. It is thus
N. Aizawa; R. Chakrabarti
2007-05-04
We note that the recently introduced fuzzy torus can be regarded as a q-deformed parafermion. Based on this picture, classification of the Hermitian representations of the fuzzy torus is carried out. The result involves Fock-type representations and new finite dimensional representations for q being a root of unity as well as already known finite dimensional ones.
Energy Science and Technology Software Center (OSTI)
002440MLTPL00 3D Torus Routing Engine Module for OFA OpenSM v. 1.0 http://www.openfabrics.org/git?p=sashak/management.git;a=sum
Methanol in the L1551 Circumbinary Torus
Glenn J. White; C. W. M. Fridlund; P. Bergman; A. Beardsmore; Rene Liseau; R. R. Phillips
2006-09-25
We report observations of gaseous methanol in an edge-on torus surrounding the young stellar object L1551 IRS5. The peaks in the torus are separated by ~ 10,000 AU from L1551 IRS5, and contain ~ 0.03 earth masses of cold methanol. We infer that the methanol abundance increases in the outer part of the torus, probably as a result of methanol evaporation from dust grain surfaces heated by the shock luminosity associated with the shocks associated with the jets of an externally located x-ray source. Any methanol released in such a cold environment will rapidly freeze again, spreading methanol throughout the circumbinary torus to nascent dust grains, planitesimals, and primitive bodies. These observations probe the initial chemical conditions of matter infalling onto the disk.
Spherical Carbon with Unique Architectures and Properties
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Spherical Carbon with Unique Architectures and Properties V.G. Pol, K.C. Lau, L.A. Curtiss, J.G. Wen, D.J. Miller, and M.M. Thackeray, Argonne National Laboratory Carbon atoms can...
Zero point energy on extra dimension: Noncommutative Torus
S. Fabi; B. Harms; G. Karatheodoris
2007-04-25
In this paper we calculate the zero point energy density experienced by observers on M^4 due to a massless scalar field defined throughout M^4 x T^2_F, where T^2_F are fuzzy extra dimensions. Using the Green's function approach we calculate the energy density for the commutative torus and the fuzzy torus. We calculate then the energy density for the fuzzy torus using the Hamiltonian approach. Agreement is shown between Green's function and Hamiltonian approaches.
Electrodynamic spherical harmonic
Andrey Novitsky
2008-03-28
Electrodynamic spherical harmonic is a second rank tensor in three-dimensional space. It allows to separate the radial and angle variables in vector solutions of Maxwell's equations. Using the orthonormalization for electrodynamic spherical harmonic, a boundary problem on a sphere can be easily solved.
Leung, Ka-Ngo
2006-11-21
A spherical neutron generator is formed with a small spherical target and a spherical shell RF-driven plasma ion source surrounding the target. A deuterium (or deuterium and tritium) ion plasma is produced by RF excitation in the plasma ion source using an RF antenna. The plasma generation region is a spherical shell between an outer chamber and an inner extraction electrode. A spherical neutron generating target is at the center of the chamber and is biased negatively with respect to the extraction electrode which contains many holes. Ions passing through the holes in the extraction electrode are focused onto the target which produces neutrons by D-D or D-T reactions.
Global Bifurcation Destroying The Experimental Torus T2
T. Pereira; M. S. Baptista; M. B. Reyes; I. L. Caldas; J. C. Sartorelli; J. Kurths
2007-06-22
We show experimentally the scenario of a two-frequency torus $T^2$ breakdown, in which a global bifurcation occurs due to the collision of a torus with an unstable periodic orbit, creating a heteroclinic saddle connection, followed by an intermittent behavior.
RADON TRANSFORM ON THE TORUS AHMED ABOUELAZ AND FRANOIS ROUVIRE
Vallette, Bruno
RADON TRANSFORM ON THE TORUS AHMED ABOUELAZ AND FRANÇOIS ROUVIÈRE Abstract. We consider the Radon-Ricci spaces etc. We consider here the n-dimensional (at) torus Tn = Rn=Zn and the Radon transform de will thus enter the picture, as in the case of Radon transforms on Zn already studied by the ...rst author
Arithmetic functions in torus and tree networks
Bhanot, Gyan (Princeton, NJ); Blumrich, Matthias A. (Ridgefield, CT); Chen, Dong (Croton On Hudson, NY); Gara, Alan G. (Mount Kisco, NY); Giampapa, Mark E. (Irvington, NY); Heidelberger, Philip (Cortlandt Manor, NY); Steinmacher-Burow, Burkhard D. (Mount Kisco, NY); Vranas, Pavlos M. (Bedford Hills, NY)
2007-12-25
Methods and systems for performing arithmetic functions. In accordance with a first aspect of the invention, methods and apparatus are provided, working in conjunction of software algorithms and hardware implementation of class network routing, to achieve a very significant reduction in the time required for global arithmetic operation on the torus. Therefore, it leads to greater scalability of applications running on large parallel machines. The invention involves three steps in improving the efficiency and accuracy of global operations: (1) Ensuring, when necessary, that all the nodes do the global operation on the data in the same order and so obtain a unique answer, independent of roundoff error; (2) Using the topology of the torus to minimize the number of hops and the bidirectional capabilities of the network to reduce the number of time steps in the data transfer operation to an absolute minimum; and (3) Using class function routing to reduce latency in the data transfer. With the method of this invention, every single element is injected into the network only once and it will be stored and forwarded without any further software overhead. In accordance with a second aspect of the invention, methods and systems are provided to efficiently implement global arithmetic operations on a network that supports the global combining operations. The latency of doing such global operations are greatly reduced by using these methods.
Magnetic surfaces in an axisymmetric torus
Skovoroda, A. A., E-mail: skovorod@nfi.kiae.ru [National Research Centre Kurchatov Institute (Russian Federation)
2013-04-15
A method is developed for specifying the boundary equilibrium magnetic surface in an axially symmetric torus by using the absolute values of the magnetic field B = B{sub s}({theta}) and the gradient of the poloidal flux vertical bar vertical bar {nabla}{Psi} vertical bar = vertical bar {nabla}{Psi} vertical bar {sub s}({theta}) in a special flux coordinate system. By setting two surface constants (e.g., the safety factor q and dp/d{Psi}) and matching the absolute values of the magnetic field and the flux gradient on a closed magnetic surface, it is possible to find all equilibrium magnetic functions (including n {center_dot} {nabla} ln B and the local shear s) and all constants (including the toroidal current J and the shear d{mu}/d{Psi}) on this surface. Such a non-traditional formulation of the boundary conditions in solving the stability problem in an axisymmetric torus allows one to impose intentional conditions on plasma confinement and MHD stability at the periphery of the system.
Saturn in hot water: viscous evolution of the Enceladus torus
Alison J. Farmer
2008-06-09
The detection of outgassing water vapor from Enceladus is one of the great breakthroughs of the Cassini mission. The fate of this water once ionized has been widely studied; here we investigate the effects of purely neutral-neutral interactions within the Enceladus torus. We find that, thanks in part to the polar nature of the water molecule, a cold (~180 K) neutral torus would undergo rapid viscous heating and spread to the extent of the observed hydroxyl cloud, before plasma effects become important. We investigate the physics behind the spreading of the torus, paying particular attention to the competition between heating and rotational line cooling. A steady-state torus model is constructed, and it is demonstrated that the torus will be observable in the millimeter band with the upcoming Herschel satellite. The relative strength of rotational lines could be used to distinguish between physical models for the neutral cloud.
Large displacement spherical joint
Bieg, Lothar F. (Albuquerque, NM); Benavides, Gilbert L. (Albuquerque, NM)
2002-01-01
A new class of spherical joints has a very large accessible full cone angle, a property which is beneficial for a wide range of applications. Despite the large cone angles, these joints move freely without singularities.
Progress in Understanding Error-field Physics in NSTX Spherical Torus Plasmas
E. Menard, R.E. Bell, D.A. Gates, S.P. Gerhardt, J.-K. Park, S.A. Sabbagh, J.W. Berkery, A. Egan, J. Kallman, S.M. Kaye, B. LeBlanc, Y.Q. Liu, A. Sontag, D. Swanson, H. Yuh, W. Zhu and the NSTX Research Team
2010-05-19
The low aspect ratio, low magnetic field, and wide range of plasma beta of NSTX plasmas provide new insight into the origins and effects of magnetic field errors. An extensive array of magnetic sensors has been used to analyze error fields, to measure error field amplification, and to detect resistive wall modes in real time. The measured normalized error-field threshold for the onset of locked modes shows a linear scaling with plasma density, a weak to inverse dependence on toroidal field, and a positive scaling with magnetic shear. These results extrapolate to a favorable error field threshold for ITER. For these low-beta locked-mode plasmas, perturbed equilibrium calculations find that the plasma response must be included to explain the empirically determined optimal correction of NSTX error fields. In high-beta NSTX plasmas exceeding the n=1 no-wall stability limit where the RWM is stabilized by plasma rotation, active suppression of n=1 amplified error fields and the correction of recently discovered intrinsic n=3 error fields have led to sustained high rotation and record durations free of low-frequency core MHD activity. For sustained rotational stabilization of the n=1 RWM, both the rotation threshold and magnitude of the amplification are important. At fixed normalized dissipation, kinetic damping models predict rotation thresholds for RWM stabilization to scale nearly linearly with particle orbit frequency. Studies for NSTX find that orbit frequencies computed in general geometry can deviate significantly from those computed in the high aspect ratio and circular plasma cross-section limit, and these differences can strongly influence the predicted RWM stability. The measured and predicted RWM stability is found to be very sensitive to the E × B rotation profile near the plasma edge, and the measured critical rotation for the RWM is approximately a factor of two higher than predicted by the MARS-F code using the semi-kinetic damping model.
Ohmic Flux Consumption During Initial Operation of the NSTX Spherical Torus
been achieved on NSTX, while faster ramps generate significant MHD activity. Discharges with IP will rely on OH current drive to generate target plasmas suitable for strong auxiliary heating to test.5, vacuum toroidal field B T = 0.3 Tesla at R 0 , plasma current I P
Detection of Disruptions in the High-Î² Spherical Torus NSTX (Technical
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfate Reducing BacteriaConnectlaser-solid interactionCrystalDesigning aDesignsfrom(Patent)Report)
Detection of Disruptions in the High-Î² Spherical Torus NSTX (Technical
Office of Scientific and Technical Information (OSTI)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfate Reducing BacteriaConnectlaser-solid interactionCrystalDesigning
From Use Cases of the Joint European Torus towards Integrated Commissioning Requirements of the ITER Tokamak
David Brown
2008-08-19
The BSSN (Baumgarte-Shapiro-Shibata-Nakamura) formulation of the Einstein evolution equations is written in spherical symmetry. These equations can be used to address a number of technical and conceptual issues in numerical relativity in the context of a single Schwarzschild black hole. One of the benefits of spherical symmetry is that the numerical grid points can be tracked on a Kruskal--Szekeres diagram. Boundary conditions suitable for puncture evolution of a Schwarzschild black hole are presented. Several results are shown for puncture evolution using a fourth--order finite difference implementation of the equations.
Hollow spherical shell manufacture
O'Holleran, T.P.
1991-11-26
A process is disclosed for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry. 3 figures.
Hollow spherical shell manufacture
O'Holleran, Thomas P. (Belleville, MI)
1991-01-01
A process for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry.
Spherical nitroguanidine process
Sanchez, John A. (Los Alamos, NM); Roemer, Edward L. (Los Alamos, NM); Stretz, Lawrence A. (Los Alamos, NM)
1990-01-01
A process of preparing spherical high bulk density nitroguanidine by dissing low bulk density nitroguanidine in N-methyl pyrrolidone at elevated temperatures and then cooling the solution to lower temperatures as a liquid characterized as a nonsolvent for the nitroguanidine is provided. The process is enhanced by inclusion in the solution of from about 1 ppm up to about 250 ppm of a metal salt such as nickel nitrate, zinc nitrate or chromium nitrate, preferably from about 20 to about 50 ppm.
Efficient Subtorus Processor Allocation in a Multi-Dimensional Torus
Weizhen Mao; Jie Chen; William Watson
2005-11-30
Processor allocation in a mesh or torus connected multicomputer system with up to three dimensions is a hard problem that has received some research attention in the past decade. With the recent deployment of multicomputer systems with a torus topology of dimensions higher than three, which are used to solve complex problems arising in scientific computing, it becomes imminent to study the problem of allocating processors of the configuration of a torus in a multi-dimensional torus connected system. In this paper, we first define the concept of a semitorus. We present two partition schemes, the Equal Partition (EP) and the Non-Equal Partition (NEP), that partition a multi-dimensional semitorus into a set of sub-semitori. We then propose two processor allocation algorithms based on these partition schemes. We evaluate our algorithms by incorporating them in commonly used FCFS and backfilling scheduling policies and conducting simulation using workload traces from the Parallel Workloads Archive. Specifically, our simulation experiments compare four algorithm combinations, FCFS/EP, FCFS/NEP, backfilling/EP, and backfilling/NEP, for two existing multi-dimensional torus connected systems. The simulation results show that our algorithms (especially the backfilling/NEP combination) are capable of producing schedules with system utilization and mean job bounded slowdowns comparable to those in a fully connected multicomputer.
Cascade of torus doubling bifurcations in a detuned laser
Krents, A A [S.P. Korolev Samara State Aerospace University, Samara (Russian Federation); Molevich, N E [Samara Branch of the P.N. Lebedev Physical Institute, Russian Academy of Sciences, Samara (Russian Federation)
2009-08-31
By using a simplified system of Maxwell-Bloch equations (with the adiabatically excluded polarisation of the medium), we studied the processes proceeding in the cross section of a light wave propagating in a wide-aperture laser emitting at the frequency detuned from the transition-line centre. It is shown that in the model under study the passage to the chaotic regime during a change in the wave propagation velocity across the aperture occurs via the doubling bifurcations of an ergodic two-dimensional torus. The spectrum of Lyapunov exponents is found and it is established that at bifurcation points a structurally unstable three-dimensional torus is produced, which gives rise to a stable doubled ergodic torus. (nonlinear optical phenomena)
Maass Cusp Forms on Singly Punctured Two-Torus
Siddig, Abubaker Ahmed Mohamed [Laboratory of Computational Sciences and Informatics, Institute for Mathematical Research Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Shah, Nurisya Mohd [Theoretical Physics Group, Department of Physics, Faculty of Science Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Zainuddin, Hishamuddin [Laboratory of Computational Sciences and Informatics, Institute for Mathematical Research Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Theoretical Physics Group, Department of Physics, Faculty of Science Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia)
2009-07-07
Quantum mechanical systems on punctured surfaces modeled by hyperbolic spaces can play an interesting role in exploring quantum chaos and in studying behaviour of future quantum nano-devices. The case of singly-punctured two-torus, for example, has been well-studied in the literature particularly for its scattering states. However, the bound states on the punctured torus given by Maass cusp forms are lesser known. In this note, we report on the algorithm of numerically computing these functions and we present ten lower-lying eigenvalues for each odd and even Maass cusp forms.
Double slotted socket spherical joint
Bieg, Lothar F. (Albuquerque, NM); Benavides, Gilbert L. (Albuquerque, NM)
2001-05-22
A new class of spherical joints is disclosed. These spherical joints are capable of extremely large angular displacements (full cone angles in excess of 270.degree.), while exhibiting no singularities or dead spots in their range of motion. These joints can improve or simplify a wide range of mechanical devices.
Milking the spherical cow: on aspherical dynamics in spherical coordinates
Pontzen, Andrew; Teyssier, Romain; Governato, Fabio; Gualandris, Alessia; Roth, Nina; Devriendt, Julien
2015-01-01
Galaxies and the dark matter halos that host them are not spherically symmetric, yet spherical symmetry is a helpful simplifying approximation for idealised calculations and analysis of observational data. The assumption leads to an exact conservation of angular momentum for every particle, making the dynamics unrealistic. But how much does that inaccuracy matter in practice for analyses of stellar distribution functions, collisionless relaxation, or dark matter core-creation? We provide a general answer to this question for a wide class of aspherical systems; specifically, we consider distribution functions that are "maximally stable", i.e. that do not evolve at first order when external potentials (which arise from baryons, large scale tidal fields or infalling substructure) are applied. We show that a spherically-symmetric analysis of such systems gives rise to the false conclusion that the density of particles in phase space is ergodic (a function of energy alone). Using this idea we are able to demonstra...
Associate Research Physicist (Post Doc, Experimental Research...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
National Spherical Torus Experiment Upgrade (NSTX-U). For present and future magnetic fusion devices to operate reliably a high plasma pressure and high power density for...
Major Milestone: PPPL completes first quadrant of the heart of...
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Major Milestone: PPPL completes first quadrant of the heart of the National Spherical Torus Experiment Upgrade By John Greenwald March 18, 2013 Tweet Widget Google Plus One Share...
Disruptions, Disruptivity, and Safer Operating Windows in the...
Office of Scientific and Technical Information (OSTI)
in the high- N National Spherical Torus Experiment (NSTX) M. Ono, et al. Nuclear Fusion 40, 557 (2000). While the overall disruption rate is rather high, configurations with...
Ashtekar Formulation of 2+1 Gravity on a Torus
N. Manojlovic; A. Mikovic
1992-04-09
Pure (2+1)-dimensional Einstein gravity is analysed in the Ashtekar formulation, when the spatial manifold is a torus. We have found a set of globally defined observables, forming a closed algebra. This allowed us to solve the quantum constraints, and to show that the reduced phase space of the Ashtekar formulation is greater then the corresponding space of the Witten formulation. Furthermore, we have found a globally defined time variable which satisfies all the requiriments of an extrinsic time variable in quantum gravity.
FPA Meeting, 10/11-12/05 Status of World ST Research Status of World Spherical Torus Research
and Energy Policy October 11-12, 2005, Washington, DC Supported by Office of Science College W&M Colorado Sch Has a Tradition of Strong Collaboration · Active bilateral exchanges UK-US on NSTX and MAST START options for economical fusion reactor Phase III Target Strategy of the All-Japan ST Research Program (Prof
Deuterium Beam Acceleration with 3rd Harmonic ICRH in Joint European Torus: Sawtooth Stabilization and Alfvén Eigenmodes
spherical harmonics for l < 20
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Michael, J. Robert [Middle Tennessee State University; Volkov, Anatoliy [Middle Tennessee State University
2015-01-23
The widely used pseudoatom formalism [Stewart (1976). Acta Cryst. A32, 565–574; Hansen & Coppens (1978). Acta Cryst. A34, 909–921] in experimental X-ray charge-density studies makes use of real spherical harmonics when describing the angular component of aspherical deformations of the atomic electron density in molecules and crystals. The analytical form of the densitynormalized Cartesian spherical harmonic functions for up to l 7 and the corresponding normalization coefficients were reported previously by Paturle & Coppens [Acta Cryst. (1988), A44, 6–7]. It was shown that the analytical form for normalization coefficients is available primarily for l 4 [Hansen & Coppens, 1978; Paturle & Coppens, 1988; Coppens (1992). International Tables for Crystallography, Vol. B, Reciprocal space, 1st ed., edited by U. Shmueli, ch. 1.2. Dordrecht: Kluwer Academic Publishers; Coppens (1997). X-ray Charge Densities and Chemical Bonding. New York: Oxford University Press]. Only in very special cases it is possible to derive an analytical representation of the normalization coefficients for 4 4 the density normalization coefficients were calculated numerically to within seven significant figures. In this study we review the literature on the density-normalized spherical harmonics, clarify the existing notations, use the Paturle–Coppens (Paturle & Coppens, 1988) method in the Wolfram Mathematica software to derive the Cartesian spherical harmonics for l 20 and determine the density normalization coefficients to 35 significant figures, and computer-generate a Fortran90 code. The article primarily targets researchers who work in the field of experimental X-ray electron density, but may be of some use to all who are interested in Cartesian spherical harmonics.
On spherically symmetric structures in GR
Angelo Loinger; Tiziana Marsico
2007-07-16
We reconsider some subtle points concerning the relativistic treatment of the gravitational fields generated by spherically symmetric structures.
Browning, P K; Evans, M; Lucini, F Arese; Lukin, V S; McClements, K G; Stanier, A
2015-01-01
Twisted magnetic flux ropes are ubiquitous in space and laboratory plasmas, and the merging of such flux ropes through magnetic reconnection is an important mechanism for restructuring magnetic fields and releasing free magnetic energy. The merging-compression scenario is one possible start up scheme for spherical tokamaks, which has been used on the Mega Amp Spherical Tokamak MAST. Two current-carrying plasma rings, or flux ropes, approach each other through the mutual attraction of their like currents, and merge, through magnetic reconnection, into a single plasma torus, with substantial plasma heating. 2D resistive MHD and Hall MHD simulations of this process are reported, and new results for the temperature distribution of ions and electrons are presented. A model of the based on relaxation theory is also described, which is now extended to tight aspect ratio geometry. This model allows prediction of the final merged state and the heating. The implications of the relaxation model for heating of the solar ...
Low energy ion distribution measurements in Madison Symmetric Torus plasmas
Titus, J. B., E-mail: jtitus@cepast.famu.edu; Mezonlin, E. D. [Florida A and M University, Tallahassee, Florida 32310 (United States); Johnson, J. A. [Pyramid Plasmas LLC, Lawrenceville, Georgia 30043 (United States)
2014-06-15
Charge-exchange neutrals contain information about the contents of a plasma and can be detected as they escape confinement. The Florida A and M University compact neutral particle analyzer (CNPA), used to measure the contents of neutral particle flux, has been reconfigured, calibrated, and installed on the Madison Symmetric Torus (MST) for high temperature deuterium plasmas. The energy range of the CNPA has been extended to cover 0.34–5.2?keV through an upgrade of the 25 detection channels. The CNPA has been used on all types of MST plasmas at a rate of 20?kHz throughout the entire discharge (?70?ms). Plasma parameter scans show that the ion distribution is most dependent on the plasma current. Magnetic reconnection events throughout these scans produce stronger poloidal electric fields, stronger global magnetic modes, and larger changes in magnetic energy all of which heavily influence the non-Maxwellian part of the ion distribution (the fast ion tail)
MODELING RESULTS FROM CESIUM ION EXCHANGE PROCESSING WITH SPHERICAL RESINS
Nash, C.; Hang, T.; Aleman, S.
2011-01-03
Ion exchange modeling was conducted at the Savannah River National Laboratory to compare the performance of two organic resins in support of Small Column Ion Exchange (SCIX). In-tank ion exchange (IX) columns are being considered for cesium removal at Hanford and the Savannah River Site (SRS). The spherical forms of resorcinol formaldehyde ion exchange resin (sRF) as well as a hypothetical spherical SuperLig{reg_sign} 644 (SL644) are evaluated for decontamination of dissolved saltcake wastes (supernates). Both SuperLig{reg_sign} and resorcinol formaldehyde resin beds can exhibit hydraulic problems in their granular (nonspherical) forms. SRS waste is generally lower in potassium and organic components than Hanford waste. Using VERSE-LC Version 7.8 along with the cesium Freundlich/Langmuir isotherms to simulate the waste decontamination in ion exchange columns, spherical SL644 was found to reduce column cycling by 50% for high-potassium supernates, but sRF performed equally well for the lowest-potassium feeds. Reduced cycling results in reduction of nitric acid (resin elution) and sodium addition (resin regeneration), therefore, significantly reducing life-cycle operational costs. These findings motivate the development of a spherical form of SL644. This work demonstrates the versatility of the ion exchange modeling to study the effects of resin characteristics on processing cycles, rates, and cold chemical consumption. The value of a resin with increased selectivity for cesium over potassium can be assessed for further development.
Axisymmetric, High-, Steady-State Plasma Torus: A "Wind Tunnel" to Develop Whole Device Models
Mauel, Michael E.
on Integrated Simulations for Magnetic Fusion Energy Sciences: Community Teleconference Presentation CD modes; no density limits; ...) · Axisymmetry (simplicity; omnigenous drifts;...) · Simple kinetics Fusion-Relevant Plasma Torus: Axisymmetric, Levitated Current Ring Fusion Relevant Physics: Particle
Zhang, J.; Wang, Y. H.; Wang, D. Z. [Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)] [Key Laboratory of Materials Modification by Laser, Electron, and Ion Beams, School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116024 (China)
2013-08-15
Understanding the routes to chaos occurring in atmospheric-pressure dielectric barrier discharge systems by changing controlling parameters is very important to predict and control the dynamical behaviors. In this paper, a route of a quasiperiodic torus to chaos via the strange nonchaotic attractor is observed in an atmospheric-pressure dielectric barrier discharge driven by triangle-wave voltage. By increasing the driving frequency, the discharge system first bifurcates to a quasiperiodic torus from a stable single periodic state, and then torus and phase-locking periodic state appear and disappear alternately. In the meantime, the torus becomes increasingly wrinkling and stretching, and gradually approaches a fractal structure with the nonpositive largest Lyapunov exponent, i.e., a strange nonchaotic attractor. After that, the discharge system enters into chaotic state. If the driving frequency is further increased, another well known route of period-doubling bifurcation to chaos is also observed.
10D Massive Type IIA Supergravities as the uplift of Parabolic M2-brane Torus bundles
del Moral, Maria Pikar Garcia
2015-01-01
We remark that the two 10D massive deformations of the $N=2$ maximal type IIA supergravity (Romans and HLW supergravity) are associated to the low energy limit of the uplift to 10D of M2-brane torus bundles with parabolic monodromy linearly and non-linearly realized respectively. Romans supergravity corresponds to M2-brane compactified on a twice-punctured torus bundle.
10D Massive Type IIA Supergravities as the uplift of Parabolic M2-brane Torus bundles
Maria Pikar Garcia del Moral; Alvaro Restuccia
2015-11-15
We remark that the two 10D massive deformations of the $N=2$ maximal type IIA supergravity (Romans and HLW supergravity) are associated to the low energy limit of the uplift to 10D of M2-brane torus bundles with parabolic monodromy linearly and non-linearly realized respectively. Romans supergravity corresponds to M2-brane compactified on a twice-punctured torus bundle.
THE CLASSIFICATION OF DEHN FILLINGS ON THE OUTER TORUS OF A 1-BRIDGE BRAID
Wu, Ying-Qing
THE CLASSIFICATION OF DEHN FILLINGS ON THE OUTER TORUS OF A 1-BRIDGE BRAID EXTERIOR WHICH PRODUCE SOLID TORI Ying-Qing Wu1 Abstract. Let K = K(w, b, t) be a 1-bridge braid in a solid torus V , and let for such Dehn fillings. 1. Introduction A knot K in a 3-manifold M is a 0-bridge knot if it is isotopic
Ideal magnetohydrodynamic equilibrium in a non-symmetric topological torus
Weitzner, Harold
2014-02-15
An alternative representation of an ideal magnetohydrodynamic equilibrium is developed. The representation is a variation of one given by A. Salat, Phys. Plasmas 2, 1652 (1995). The system of equations is used to study the possibility of non-symmetric equilibria in a topological torus, here an approximate rectangular parallelopiped, with periodicity in two of the three rectangular coordinates. An expansion is carried out in the deviation of pressure surfaces from planes. Resonances are manifest in the process. Nonetheless, provided the magnetic shear is small, it is shown that it is possible to select the magnetic fields and flux surfaces in such a manner that no singularities appear on resonant surfaces. One boundary surface of the parallelopiped is not arbitrary but is dependent on the equilibrium in question. A comparison of the solution sets of axisymmetric and non-axisymmetric equilibria suggests that the latter have a wider class of possible boundary shapes but more restrictive rotational transform profiles. No proof of convergence of the series is given.
The alternative model of the spherical oscillator
Levon Mardoyan
2007-08-14
The quasiradial wave functions and energy spectra of the alternative model of spherical oscillator on the $D$-dimensional sphere and two-sheeted hyperboloid are found.
Three-point spherical mirror mount
Cutburth, R.W.
1984-01-23
A three-point spherical mirror mount for use with lasers is disclosed. The improved mirror mount is adapted to provide a pivot ring having an outer surface with at least three spaced apart mating points to engage an inner spherical surface of a support housing.
Fourier Modeling of the Radio Torus Surrounding Supernova 1987A
C. -Y. Ng; B. M. Gaensler; L. Staveley-Smith; R. N. Manchester; M. J. Kesteven; L. Ball; A. K. Tzioumis
2008-05-27
We present detailed Fourier modeling of the radio remnant of Supernova 1987A, using high-resolution 9 GHz and 18 GHz data taken with the Australia Telescope Compact Array over the period 1992 to 2008. We develop a parameterized three-dimensional torus model for the expanding radio shell, in which the emission is confined to an inclined equatorial belt; our model also incorporates both a correction for light travel-time effects and an overall east-west gradient in the radio emissivity. By deriving an analytic expression for the two-dimensional Fourier transform of the projected three-dimensional brightness distribution, we can fit our spatial model directly to the interferometric visibility data. This provides robust estimates to the radio morphology at each epoch. The best-fit results suggest a constant remnant expansion at 4000 +/- 400 km/s over the 16-year period covered by the observations. The model fits also indicate substantial mid-latitude emission, extending to 40 degree on either side of the equatorial plane. This likely corresponds to the extra-planar structure seen in H$\\alpha$ and Ly$\\alpha$ emission from the supernova reverse shock, and broadly supports hydrodynamic models in which the complex circumstellar environment was produced by a progression of interacting winds from the progenitor. Our model quantifies the clear asymmetry seen in the radio images: we find that the eastern half of the radio remnant is consistently ~40 brighter than the western half at all epochs, which may result from an asymmetry in the ejecta distribution between these two hemispheres.
Osmotic buckling of spherical capsules
Sebastian Knoche; Jan Kierfeld
2014-09-11
We study the buckling of elastic spherical shells under osmotic pressure with the osmolyte concentration of the exterior solution as control parameter. We compare our results for the bifurcation behavior with results for buckling under mechanical pressure control, that is, with an empty capsule interior. We find striking differences for the buckling states between osmotic and mechanical buckling. Mechanical pressure control always leads to fully collapsed states with opposite sides in contact, whereas uncollapsed states with a single finite dimple are generic for osmotic pressure control. For sufficiently large interior osmolyte concentrations, osmotic pressure control is qualititatively similar to buckling under volume control with the volume prescribed by the osmolyte concentrations inside and outside the shell. We present a quantitative theory which also captures the influence of shell elasticity on the relation between osmotic pressure and volume. These findings are relevant for the control of buckled shapes in applications. We show how the osmolyte concentration can be used to control the volume of buckled shells. An accurate analytic formula is derived for the relation between the osmotic pressure, the elastic moduli and the volume of buckled capsules. This also allows to use elastic capsules as osmotic pressure sensors or to deduce elastic properties and the internal osmolyte concentration from shape changes in response to osmotic pressure changes. We apply our findings to published experimental data on polyelectrolyte capsules.
Bounce-free spherical hydrodynamic implosion
Kagan, Grigory; Tang Xianzhu; Hsu, Scott C.; Awe, Thomas J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2011-12-15
In a bounce-free spherical hydrodynamic implosion, the post-stagnation hot core plasma does not expand against the imploding flow. Such an implosion scheme has the advantage of improving the dwell time of the burning fuel, resulting in a higher fusion burn-up fraction. The existence of bounce-free spherical implosions is demonstrated by explicitly constructing a family of self-similar solutions to the spherically symmetric ideal hydrodynamic equations. When applied to a specific example of plasma liner driven magneto-inertial fusion, the bounce-free solution is found to produce at least a factor of four improvement in dwell time and fusion energy gain.
FMEA on the superconducting torus for the Jefferson Lab 12 GeV accelerator upgrade
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Ghoshal, Probir K.; Biallas, George H.; Fair, Ruben J.; Rajput-Ghoshal, Renuka; Schneider, William J.; Legg, Robert A.; Kashy, David H.; Hogan, John P.; Wiseman, Mark A.; Luongo, Cesar; et al
2015-01-16
As part of the Jefferson Lab 12GeV accelerator upgrade project, Hall B requires two conduction cooled superconducting magnets. One is a magnet system consisting of six superconducting trapezoidal racetrack-type coils assembled in a toroidal configuration and the second is an actively shielded solenoidal magnet system consisting of 5 coils. Both magnets are to be wound with Superconducting Super Collider-36 NbTi strand Rutherford cable soldered into a copper channel. This paper describes the various failure modes in torus magnet along with the failure modes that could be experienced by the torus and its interaction with the solenoid which is located inmore »close proximity.« less
Method for making spherical binderless pellets
Grubbs, Donald K. (Rector, PA); Kochanowski, Andrew T. (Spring Church, PA)
1983-01-01
A method for making spherical binderless pellets using a rotating drum mixer whereby at least a portion of the particles comprising the pellets is comprised of coking coal particles.
Sphericity determination using resonant ultrasound spectroscopy
Dixon, R.D.; Migliori, A.; Visscher, W.M.
1994-10-18
A method is provided for grading production quantities of spherical objects, such as roller balls for bearings. A resonant ultrasound spectrum (RUS) is generated for each spherical object and a set of degenerate sphere-resonance frequencies is identified. From the degenerate sphere-resonance frequencies and known relationships between degenerate sphere-resonance frequencies and Poisson's ratio, a Poisson's ratio can be determined, along with a 'best' spherical diameter, to form spherical parameters for the sphere. From the RUS, fine-structure resonant frequency spectra are identified for each degenerate sphere-resonance frequency previously selected. From each fine-structure spectrum and associated sphere parameter values an asphericity value is determined. The asphericity value can then be compared with predetermined values to provide a measure for accepting or rejecting the sphere. 14 figs.
Axisymmetric, High-, Steady-State Plasma Torus: A "Wind-Tunnel" to Develop Whole Device Models
Mauel, Michael E.
Axisymmetric, High-, Steady-State Plasma Torus: A "Wind-Tunnel" to Develop Whole Device Models Mike College, Hanover, NH White Paper for the 2015 DOE Integrated Simulations Workshop (Topics: C, D) Motivation The development of experimentally-validated whole device models is a grand challenge of fusion
Thermoelectric Rotating Torus for Fusion A. B. Hassam and Yi-Min Huang
Hassam, Adil
Thermoelectric Rotating Torus for Fusion A. B. Hassam and Yi-Min Huang Institute for Plasma power maintains the rotation and also heats the plasma. The thermoelectric effect from the resultingRevLett.91.195002 PACS numbers: 52.58.c, 52.30.q, 52.55.s In magnetized plasma, thermoelectric currents
Preliminary Physics Motivation and Engineering Design Assessment of the National High Power Torus
Robert D. Woolley
2009-06-11
In April 2006, Dr. Ray Orbach, Director of the DOE Office of Science, challenged the fusion community to "propose a new facility... which will put the U.S. at the lead in world fusion science." Analysis of the gaps between expected ITER performance and the requirements of a demonstration power plant (Demo) pointed to the critical and urgent need to develop fusion-relvant plasma-material interface (PMI) solutions consistent with sustained high plasma performance. A survey of world fusion program indicated that present and planned experimental devices do not advance the PMI issue beyond ITER, and a major dedicated experimental facility is warranted. Such a facility should provide the flexibility and access needed to solve plasma boundary challenges related to divertor heat flux and particle exhaust while also developing methods to minimize hydrogenic isotope retention and remaining compatible with high plasma performance.
45Fuel Level in a Spherical Tank Spherical tanks are found in many
45Fuel Level in a Spherical Tank Spherical tanks are found in many different situations, from the storage of cryogenic liquids, to fuel tanks. Under the influence of gravity, or acceleration, the liquid then be designed to measure where the surface of the liquid is, and from this derive h. Problem 1 - Slice the fluid
Lagrange multiplier and Wess-Zumino variable as large extra dimensions in the torus universe
Nejad, Salman Abarghouei; Monemzadeh, Majid
2015-01-01
We study the effect of the topology of universe by gauging the non-relativistic particle model on the torus and 3-torus, using the symplectic formalism of constrained systems and embedding those models on extended phase-spaces. Also, we obtain the generators of the gauge transformations for gauged models. Extracting the corresponding Poisson structure of the existed constraints, we show the effect of the topology on the canonical structure of the phase-spaces of those models and suggest some phenomenology to prove the topology of the universe and probable non-commutative structure of the space. In addition, we show that the number of large extra dimensions in the Phase-spaces of the gauged embeded models are exactly two. Moreover, in the classical form, we talk over MOND theory in order to study the origin of the terms appeared in the gauged theory, which modify the Newton's second law.
Brachistochrone of a Spherical Uniform Mass Distribution
David R. Mitchell
2008-08-23
We solve the brachistochrone problem for a particle travelling through a spherical mass distribution of uniform density. We examine the connection between this problem and the popular "gravity elevator" result. The solution is compared to the well known brachistochrone problem of a particle in a uniform gravitational field.
CONCAVE LIQUID METAL DIVERTOR FOR SPHERICAL TOKAMAKS
Harilal, S. S.
CONCAVE LIQUID METAL DIVERTOR FOR SPHERICAL TOKAMAKS Isak Konkashbaev and Ahmed Hassanein Argonne considered for tokamak divertors in magnetic fusion devices. One of such concepts is the use of liquid metals associated with a liquid metal being in the strong tokamak magnetic field. This is particularly important
Spherical fields as nonparaxial accelerating waves
Miguel A. Alonso; Miguel A. Bandres
2012-11-07
We introduce nonparaxial spatially accelerating waves whose two-dimensional transverse profiles propagate along semicircular trajectories while approximately preserving their shape. We derive these waves by considering imaginary displacements on spherical fields, leading to simple closed-form expressions. The structure of these waves also allows the closed-form description of pulses.
Condensates and instanton - torus knot duality. Hidden Physics at UV scale
A. Gorsky; A. Milekhin
2014-12-29
We establish the duality between the torus knot superpolynomials or the Poincare polynomials of the Khovanov homology and particular condensates in Omega-deformed 5D supersymmetric QED compactified on a circle with 5d Chern-Simons(CS) term. This is the generalization of the Witten's recipe of the evaluation of the knot polynomials via Wilson loops in 3d CS theory for case of the torus knots. It is explicitly shown that $n$-instanton contribution to the condensate of the massless flavor in the background of four-observable, which can be associated with some composite defect, exactly coincides with the superpolynomial of the T(n,nk+1) torus knot where k - is the level of CS term. In contrast to the previously known results, the particular torus knot corresponds not to the partition function of the gauge theory but to the particular instanton contribution and summation over the knots has to be performed in order to obtain the complete answer. The instantons are sitting almost at the top of each other and the physics of the "fat point" where the UV degrees of freedom are slaved with point-like instantons turns out to be quite rich. Also also see knot polynomials in the quantum mechanics on the instanton moduli space. We consider the different limits of this correspondence focusing at their physical interpretation and compare the algebraic structures at the both sides of the correspondence. Using the AGT correspondence, we establish a connection between superpolynomials for unknots and q-deformed DOZZ factors which suggests the interpretation of the composite defect.
Two intervals R\\'enyi entanglement entropy of compact free boson on torus
Liu, Feihu
2015-01-01
We compute the $N=2$ R\\'enyi entanglement entropy of two intervals at equal time in a circle, for the theory of a 2d compact complex free scalar at finite temperature. This is carried out by performing functional integral on a genus 3 ramified cover of the torus, wherein the quantum part of the integral is captured by the four point function of twist fields on the worldsheet torus, and the classical piece is given by summing over winding modes of the genus 3 surface onto the target space torus. The final result is given in terms of a product of theta function and certain multi-dimensional theta function. We demonstrate the T-duality invariance of the result. We also study its low temperature limit. In the case in which the size of the intervals and of their separation are much smaller than the whole system, our result is in exact agreement with the known result for two intervals on an infinite system at zero temperature \\cite{eeoftwo}. In the case in which the separation between the two intervals is much smal...
ESCUELA TCNICA SUPERIOR Using Spherical Harmonic Virtual Screening Tools
Ritchie, Dave
energy Â EAL Â electron affinity Â L Â polarizability Â· Encode as Spherical Harmonic expansions to order
Dynamic Spherical Volumetric Simplex Splines with Applications in Biomedical Simulation
Hua, Jing
Dynamic Spherical Volumetric Simplex Splines with Applications in Biomedical Simulation Yunhao Tan computational framework based on dy- namic spherical volumetric simplex splines for simulation of genus- zero to reconstruct the high-fidelity digi- tal model of a real-world object with spherical volumetric simplex splines
Generalized harmonic formulation in spherical symmetry
Evgeny Sorkin; Matthew W. Choptuik
2010-04-30
In this pedagogically structured article, we describe a generalized harmonic formulation of the Einstein equations in spherical symmetry which is regular at the origin. The generalized harmonic approach has attracted significant attention in numerical relativity over the past few years, especially as applied to the problem of binary inspiral and merger. A key issue when using the technique is the choice of the gauge source functions, and recent work has provided several prescriptions for gauge drivers designed to evolve these functions in a controlled way. We numerically investigate the parameter spaces of some of these drivers in the context of fully non-linear collapse of a real, massless scalar field, and determine nearly optimal parameter settings for specific situations. Surprisingly, we find that many of the drivers that perform well in 3+1 calculations that use Cartesian coordinates, are considerably less effective in spherical symmetry, where some of them are, in fact, unstable.
Fast Ion Stabilization of the Ion Temperature Gradient Driven Modes in the Joint European Torus Hybrid-Scenario Plasmas: A Trigger Mechanism for Internal Transport Barrier Formation
A New Sawtooth Control Mechanism Relying on Toroidally Propagating Ion Cyclotron Resonance Frequency Waves: Theory and Joint European Torus Tokamak Experimental Evidence
Afterburning in spherical premixed turbulent explosions
Bradley, D.; Lawes, M.; Scott, M.J. . Dept. of Mechanical Engineering); Mushi, E.M.J. )
1994-12-01
During the early stages of spherical turbulent flame propagation, more than half of the gas behind the visible flame front may be unburned. Previous models of the afterburning of the gas behind the apparent flame front have been extended in the present work, to include the effects of flame quenching, consequent upon localized flame stretch. The predictions of the model cover, the spatial and temporal variations of the fraction burned, the flame propagation rate, and the mass burning rate. They are all in dimensionless form and are well supported by associated experimental measurements in a fan-stirred bomb with controlled turbulence. The proportion of the gas that is unburned decreases with time and increases with the product of the Karlovitz stretch factor and the Lewis number. Simultaneous photographs were taken of the spherical schlieren image and of that due to Mie scattering from small seed particles in a thin laser sheet that sectioned the spherical flame. These clearly showed the amount of unburned gas within the sphere and, along with other evidence suggest laminar flamelet burning across a scale of distance which is close to the Taylor confirm the predictions of the fraction of gas unburned and of the rate at which it is burning.
An Engineering Evaluation of Spherical Resorcinol Formaldehyde Resin
Birdwell Jr, Joseph F; Lee, Denise L; Taylor, Paul Allen; Collins, Robert T; Hunt, Rodney Dale
2010-09-01
A small column ion exchange (SCIX) system has been proposed for removal of cesium from caustic, supernatant, and dissolved salt solutions stored or generated from high-level tank wastes at the US Department of Energy (DOE) Hanford Site and Savannah River Sites. In both instances, deployment of SCIX systems, either in-tank or near-tank, is a means of expediting waste pretreatment and dispositioning with minimal or no new infrastructure requirements. Conceptually, the treatment approach can utilize a range of ion exchange media. Previously, both crystalline silicotitanate (CST), an inorganic, nonelutable sorbent, and resorcinol-formaldehyde (RF), an organic, elutable resin, have been considered for cesium removal from tank waste. More recently, Pacific Northwest National Laboratory (PNNL) evaluated use of SuperLig{reg_sign} 644, an elutable ion exchange medium, for the subject application. Results of testing indicate hydraulic limitations of the SuperLig{reg_sign} resin, specifically a high pressure drop through packed ion exchange columns. This limitation is likely the result of swelling and shrinkage of the irregularly shaped (granular) resin during repeated conversions between sodium and hydrogen forms as the resin is first loaded then eluted. It is anticipated that a similar flow limitation would exist in columns packed with conventional, granular RF resin. However, use of spherical RF resin is a likely means of mitigating processing limitations due to excessive pressure drop. Although size changes occur as the spherical resin is cycled through loading and elution operations, the geometry of the resin is expected to effectively mitigate the close packing that leads to high pressure drops across ion exchange columns. Multiple evaluations have been performed to determine the feasibility of using spherical RF resin and to obtain data necessary for design of an SCIX process. The work performed consisted of examination of radiation effects on resin performance, quantification of cesium adsorption performance as a function of operating temperature and pH, and evaluation of sodium uptake (titration) as function of pH and counteranion concentration. The results of these efforts are presented in this report. Hydraulic performance of the resin and the use of eluant alternatives to nitric acid have also been evaluated and have been reported elsewhere (Taylor 2009, Taylor and Johnson 2009).
Torus Formation in Neutron Star Mergers and Well-Localized Short Gamma-Ray Bursts
R. Oechslin; H. -Th. Janka
2006-02-22
Merging neutron stars (NSs) are hot candidates for the still enigmatic sources of short gamma-ray bursts (GRBs). If the central engines of the huge energy release are accreting relic black holes (BHs) of such mergers, it is important to understand how the properties of the BH-torus systems, in particular disc masses and mass and rotation rate of the compact remnant, are linked to the characterizing parameters of the NS binaries. For this purpose we present relativistic smoothed particle hydrodynamics simulations with conformally flat approximation of the Einstein field equations and a physical, non-zero temperature equation of state. Thick disc formation is highlighted as a dynamical process caused by angular momentum transfer through tidal torques during the merging process of asymmetric systems or in the rapidly spinning triaxial post-merger object. Our simulations support the possibility that the first well-localized short and hard GRBs 050509b, 050709, 050724, 050813 have originated from NS merger events and are powered by neutrino-antineutrino annihilation around a relic BH-torus system. Using model parameters based on this assumption, we show that the measured GRB energies and durations lead to estimates for the accreted masses and BH mass accretion rates which are compatible with theoretical expectations. In particular, the low energy output and short duration of GRB 050509b set a very strict upper limit of less than 100 ms for the time interval after the merging until the merger remnant has collapsed to a BH, leaving an accretion torus with a small mass of only about 0.01 solar masses. This favors a (nearly) symmetric NS+NS binary with a typical mass as progenitor system.
Tomuro, H.; Asai, T.; Iguchi, K.; Takahashi, Ts.; Hirano, Y. [Department of Physics, College of Science and Technology, Nihon University, Tokyo 101-8308 (Japan)
2010-10-15
A compact tomography camera system consisting of a photomultiplier tube, a multislit optical system, and a band-pass interference filter has been developed. The viewing area and spatial resolution can be configured by the arrangement of the slit system. The camera system has been specially designed for self-organized compact torus experiments having strong magnetohydrodynamics events with a submicrosecond time-scale. The developed system has been tested on a field-reversed configuration formed by the field-reversed theta-pinch. Performance evaluation of the system has been performed by comparison to the former optical system.
Spherical Accretion with Anisotropic Thermal Conduction
Prateek Sharma; Eliot Quataert; James M. Stone
2008-07-05
We study the effects of anisotropic thermal conduction on magnetized spherical accretion flows using global axisymmetric MHD simulations. In low collisionality plasmas, the Bondi spherical accretion solution is unstable to the magnetothermal instability (MTI). The MTI grows rapidly at large radii where the inflow is subsonic. For a weak initial field, the MTI saturates by creating a primarily radial magnetic field, i.e., by aligning the field lines with the background temperature gradient. The saturation is quasilinear in the sense that the magnetic field is amplified by a factor of $\\sim 10-30$ independent of the initial field strength (for weak fields). In the saturated state, the conductive heat flux is much larger than the convective heat flux, and is comparable to the field-free (Spitzer) value (since the field lines are largely radial). The MTI by itself does not appreciably change the accretion rate $\\dot M$ relative to the Bondi rate $\\dot M_B$. However, the radial field lines created by the MTI are amplified by flux freezing as the plasma flows in to small radii. Oppositely directed field lines are brought together by the converging inflow, leading to significant resistive heating. When the magnetic energy density is comparable to the gravitational potential energy density, the plasma is heated to roughly the virial temperature; the mean inflow is highly subsonic; most of the energy released by accretion is transported to large radii by thermal conduction; and the accretion rate $\\dot M \\ll \\dot M_B$. The predominantly radial magnetic field created by the MTI at large radii in spherical accretion flows may account for the stable Faraday rotation measure towards Sgr A* in the Galactic Center.
Quantum Radiation of Uniformly Accelerated Spherical Mirrors
V. Frolov; D. Singh
2001-06-07
We study quantum radiation generated by a uniformly accelerated motion of small spherical mirrors. To obtain Green's function for a scalar massless field we use Wick's rotation. In the Euclidean domain the problem is reduced to finding an electric potential in 4D flat space in the presence of a metallic toroidal boundary. The latter problem is solved by a separation of variables. After performing an inverse Wick's rotation we obtain the Hadamard function in the wave-zone regime and use it to calculate the vacuum fluctuations and the vacuum expectation for the energy density flux in the wave zone.
Karney, Charles
VOLUME54, NUMBER9 PHYSICAL REVIEW LETTERS 4 MARCH1985 Conversion of Wave Energy to Magnetic Field Energy in a Plasma Torus N. J. Fisch and C. F. F. Karney Plasma Physics Laboratory, Princeton University on the Princeton Large Torus (PLT)' have converted wave energy to poloidal field energy with the remarkable
Karney, Charles
VOLUME54, NUMBER9 PHYSICAL REVIEW LETTERS 4 MARCH1985 Conversion of Wave Energy to Magnetic Field on the Princeton Large Torus (PLT)' have converted wave energy to poloidal field energy with the remarkable Energy in a Plasma Torus N. J. Fisch and C. F. F. Karney Plasma Physics Laboratory, Princeton University
Conformal perturbation theory and higher spin entanglement entropy on the torus
Shouvik Datta; Justin R. David; S. Prem Kumar
2015-04-10
We study the free fermion theory in 1+1 dimensions deformed by chemical potentials for holomorphic, conserved currents at finite temperature and on a spatial circle. For a spin-three chemical potential \\mu, the deformation is related at high temperatures to a higher spin black hole in hs[0] theory on AdS_3 spacetime. We calculate the order \\mu^2 corrections to the single interval Renyi and entanglement entropies on the torus using the bosonized formulation. A consistent result, satisfying all checks, emerges upon carefully accounting for both perturbative and winding mode contributions in the bosonized language. The order \\mu^2 corrections involve integrals that are finite but potentially sensitive to contact term singularities. We propose and apply a prescription for defining such integrals which matches the Hamiltonian picture and passes several non-trivial checks for both thermal corrections and the Renyi entropies at this order. The thermal corrections are given by a weight six quasi-modular form, whilst the Renyi entropies are controlled by quasi-elliptic functions of the interval length with modular weight six. We also point out the well known connection between the perturbative expansion of the partition function in powers of the spin-three chemical potential and the Gross-Taylor genus expansion of large-N Yang-Mills theory on the torus. We note the absence of winding mode contributions in this connection, which suggests qualitatively different entanglement entropies for the two systems.
TORUS: Theory of Reactions for Unstable iSotopes - Year 1 Continuation and Progress Report
Arbanas, G; Elster, C; Escher, J; Mukhamedzhanov, A; Nunes, F; Thompson, I J
2011-02-24
The TORUS collaboration derives its name from the research it focuses on, namely the Theory of Reactions for Unstable iSotopes. It is a Topical Collaboration in Nuclear Theory, and funded by the Nuclear Theory Division of the Office of Nuclear Physics in the Office of Science of the Department of Energy. The funding started on June 1, 2010, it will have been running for nine months by the date of submission of this Annual Continuation and Progress Report on March 1, 2011. The extent of funding was reduced from the original application, and now supports one postdoctoral researcher for the years 1 through 3. The collaboration brings together as Principal Investigators a large fraction of the nuclear reaction theorists currently active within the USA. The mission of the TORUS Topical Collaboration is to develop new methods that will advance nuclear reaction theory for unstable isotopes by using three-body techniques to improve direct-reaction calculations, and, by using a new partial-fusion theory, to integrate descriptions of direct and compound-nucleus reactions. This multi-institution collaborative effort is directly relevant to three areas of interest: the properties of nuclei far from stability; microscopic studies of nuclear input parameters for astrophysics, and microscopic nuclear reaction theory.
Nuclear physics with spherically symmetric supernova models
M. Liebendoerfer; T. Fischer; C. Fröhlich; F. -K. Thielemann; S. Whitehouse
2007-08-31
Few years ago, Boltzmann neutrino transport led to a new and reliable generation of spherically symmetric models of stellar core collapse and postbounce evolution. After the failure to prove the principles of the supernova explosion mechanism, these sophisticated models continue to illuminate the close interaction between high-density matter under extreme conditions and the transport of leptons and energy in general relativistically curved space-time. We emphasize that very different input physics is likely to be relevant for the different evolutionary phases, e.g. nuclear structure for weak rates in collapse, the equation of state of bulk nuclear matter during bounce, multidimensional plasma dynamics in the postbounce evolution, and neutrino cross sections in the explosive nucleosynthesis. We illustrate the complexity of the dynamics using preliminary 3D MHD high-resolution simulations based on parameterized deleptonization. With established spherically symmetric models we show that typical features of the different phases are reflected in the predicted neutrino signal and that a consistent neutrino flux leads to electron fractions larger than 0.5 in neutrino-driven supernova ejecta.
Understanding pop-ins in spherical nanoindentation
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Pathak, Siddhartha; Riesterer, Jessica L.; Kalidindi, Surya R.; Michler, Johann
2014-10-24
In this study, pop-ins, or sudden displacement-bursts at constant load in a nanoindentation test, are typically attributed to the difficulty of setting up potent dislocation sources in the very small indentation zones in these experiments. Such displacement (and strain) bursts would intuitively indicate a sharp drop in stress during the pop-in event itself. However, spherical indentation stress-strain curves routinely exhibit a high and stable indentation stress value during the pop-in, and the indentation stresses decrease only after a further finite amount of additional indentation displacement has been applied. In order to understand this discrepancy, we utilize a combination of interruptedmore »spherical indentation tests along with depth profiling of the residual indentation surfaces using in-situ atomic force microscopy (AFM) to study pop-ins. The AFM surface profile maps show that there is an asymmetric profile change over a limited region around the indentation contact area for a single pop-in; the asymmetry disappears upon further loading beyond the pop-in. A plausible sequence of physical processes (related to metal plasticity) occurring underneath the indenter during and immediately after the occurrence of the pop-in is proposed to explain these observations.« less
Quasi-spherical direct drive fusion.
VanDevender, J. Pace; Abbott, Lucas M.; Langston, William L.; McDaniel, Dillon Heirman; Nash, Thomas J.; Roderick, Norman Frederick; Silva, M.
2007-01-01
The authors present designs of quasi-spherical direction drive z-pinch loads for machines such as ZR at 28 MA load current with a 150 ns implosion time (QSDDI). A double shell system for ZR has produced a 2D simulated yield of 12 MJ, but the drive for this system on ZR has essentially no margin. A double shell system for a 56 MA driver at 150 ns implosion has produced a simulated yield of 130 MJ with considerable margin in attaining the necessary temperature and density-radius product for ignition. They also represent designs for a magnetically insulated current amplifier, (MICA), that modify the attainable ZR load current to 36 MA with a 28 ns rise time. The faster pulse provided by a MICA makes it possible to drive quasi-spherical single shell implosions (QSDD2). They present results from 1D LASNEX and 2D MACH2 simulations of promising low-adiabat cryogenic QSDD2 capsules and 1D LASNEX results of high-adiabat cryogenic QSDD2 capsules.
efficient spectral-galerkin methods iv. spherical geometries
1999-10-21
EFFICIENT SPECTRAL-GALERKIN METHODS IV. SPHERICAL GEOMETRIES. ?. JIE SHEN†. SIAM J. SCI. COMPUT. c 1999 Society for Industrial and Applied ...
Dynamical friction force exerted on spherical bodies
O. Esquivel; B. Fuchs
2007-04-30
We present a rigorous calculation of the dynamical friction force exerted on a spherical massive perturber moving through an infinite homogenous system of field stars. By calculating the shape and mass of the polarization cloud induced by the perturber in the background system, which decelerates the motion of the perturber, we recover Chandrasekhar's drag force law with a modified Coulomb logarithm. As concrete examples we calculate the drag force exerted on a Plummer sphere or a sphere with the density distribution of a Hernquist profile. It is shown that the shape of the perturber affects only the exact form of the Coulomb logarithm. The latter converges on small scales, because encounters of the test and field stars with impact parameters less than the size of the massive perturber become inefficient. We confirm this way earlier results based on the impulse approximation of small angle scatterings.
Dynamical friction force exerted on spherical bodies
Esquivel, O
2007-01-01
We present a rigorous calculation of the dynamical friction force exerted on a spherical massive perturber moving through an infinite homogenous system of field stars. By calculating the shape and mass of the polarization cloud induced by the perturber in the background system, which decelerates the motion of the perturber, we recover Chandrasekhar's drag force law with a modified Coulomb logarithm. As concrete examples we calculate the drag force exerted on a Plummer sphere or a sphere with the density distribution of a Hernquist profile. It is shown that the shape of the perturber affects only the exact form of the Coulomb logarithm. The latter converges on small scales, because encounters of the test and field stars with impact parameters less than the size of the massive perturber become inefficient. We confirm this way earlier results based on the impulse approximation of small angle scatterings.
Thermodynamic motivations of spherically symmetric static metrics
H. Moradpour; S. Nasirimoghadam
2015-06-14
Bearing the thermodynamic arguments together with the two definitions of mass in mind, we try to find metrics with spherical symmetry. We consider the adiabatic condition along with the Gong-Wang mass, and evaluate the $g_{rr}$ element which points to a null hypersurface. In addition, we generalize the thermodynamics laws to this hypersurface to find its temperature and thus the corresponding surface gravity which enables us to get a relation for the $g_{tt}$ element. Finally, we investigate the mathematical and physical properties of the discovered metric in the Einstein relativity framework which shows that the primary mentioned null hypersurface is an event horizon. We also show that if one considers the Misner-Sharp mass in the calculations, the Schwarzschild metric will be got. The relationship between the two mass definitions in each metric is studied. The results of considering the geometrical surface gravity are also addressed.
Thermodynamic motivations of spherically symmetric static metrics
Moradpour, H
2015-01-01
Bearing the thermodynamic arguments together with the two definitions of mass in mind, we try to find metrics with spherical symmetry. We consider the adiabatic condition along with the Gong-Wang mass, and evaluate the $g_{rr}$ element which points to a null hypersurface. In addition, we generalize the thermodynamics laws to this hypersurface to find its temperature and thus the corresponding surface gravity which enables us to get a relation for the $g_{tt}$ element. Finally, we investigate the mathematical and physical properties of the discovered metric in the Einstein relativity framework which shows that the primary mentioned null hypersurface is an event horizon. We also show that if one considers the Misner-Sharp mass in the calculations, the Schwarzschild metric will be got. The relationship between the two mass definitions in each metric is studied. The results of considering the geometrical surface gravity are also addressed.
Polymer ejection from strong spherical confinement
J. Piili; R. P. Linna
2015-05-27
We examine the ejection of an initially strongly confined flexible polymer from a spherical capsid through a nanoscale pore. We use molecular dynamics for unprecedentedly high initial monomer densities. We show that the time for an individual monomer to eject grows exponentially with the number of ejected monomers. By measurements of the force at the pore we show this dependence to be a consequence of the excess free energy of the polymer due to confinement growing exponentially with the number of monomers initially inside the capsid. We show that the pressure inside the capsid driving the ejection dominates the process that is characterized by the ejection time growing linearly with the lengths of different polymers. We show that the superlinear dependence obtained for polymers amenable to computer simulations results from a finite-size effect due to the final retraction of polymers' tails from capsids.
Hydrogen atom in crossed electric and magnetic fields: Phase space topology and torus quantization for the periodic orbits in a strongly coupled multidimen- sional Hamiltonian system, namely the hydrogen atom.15.Gy, 05.45.-a, 45.20.Jj I. INTRODUCTION The hydrogen atom in crossed electric and magnetic fields
arXiv:astro-ph/010224014Feb2001 A dusty torus around the luminous young star LkH 101
Tuthill, Peter
, thermonuclear fusion begins. The remaining disk, which can still contain up to 0.3 times the mass of the star[3arXiv:astro-ph/010224014Feb2001 A dusty torus around the luminous young star LkH 101 Peter G. A star forms when a cloud of dust and gas collapses. It is generally believed that this collapse first
Reverberation measurements of the inner radius of the dust torus in 17 Seyfert galaxies
Koshida, Shintaro [Center of Astro Engineering and Department of Electrical Engineering, Pontificia Univercsidad Catolica de Chile, Av. Vicuna Mackenna 4868 (Chile); Minezaki, Takeo; Yoshii, Yuzuru; Sakata, Yu; Sugawara, Shota [Institute of Astronomy, School of Science, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan); Kobayashi, Yukiyasu; Suganuma, Masahiro [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Enya, Keigo [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1, Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan); Tomita, Hiroyuki; Aoki, Tsutomu [Kiso Observatory, Institute of Astronomy, School of Science, University of Tokyo, 10762-30 Mitake, Kiso, Nagano 397-0101 (Japan); Peterson, Bruce A., E-mail: skoshida@ing.puc.cl, E-mail: minezaki@ioa.s.u-tokyo.ac.jp [Mount Stromlo Observatory, Research School of Astronomy and Astrophysics, Australian National University, Weston Creek P.O., ACT 2611 (Australia)
2014-06-20
We present the results of a dust reverberation survey for 17 nearby Seyfert 1 galaxies, which provides the largest homogeneous data collection for the radius of the innermost dust torus. A delayed response of the K-band light curve after the V-band light curve was found for all targets, and 49 measurements of lag times between the flux variation of the dust emission in the K band and that of the optical continuum emission in the V band were obtained by the cross-correlation function analysis and also by an alternative method for estimating the maximum likelihood lag. The lag times strongly correlated with the optical luminosity in the luminosity range of M{sub V} = –16 to –22 mag, and the regression analysis was performed to obtain the correlation log ?t (days) = –2.11 – 0.2 M{sub V} assuming ?t?L {sup 0.5}, which was theoretically expected. We discuss the possible origins of the intrinsic scatter of the dust lag-luminosity correlation, which was estimated to be approximately 0.13 dex, and we find that the difference of internal extinction and delayed response of changes in lag times to the flux variations could have partly contributed to intrinsic scatter. However, we could not detect any systematic change of the correlation with the subclass of the Seyfert type or the Eddington ratio. Finally, we compare the dust reverberation radius with the near-infrared interferometric radius of the dust torus and the reverberation radius of broad Balmer emission lines. The interferometric radius in the K band was found to be systematically larger than the dust reverberation radius in the same band by the about a factor of two, which could be interpreted by the difference between the flux-weighted radius and response-weighted radius of the innermost dust torus. The reverberation radius of the broad Balmer emission lines was found to be systematically smaller than the dust reverberation radius by about a factor of four to five, which strongly supports the unified scheme of the Seyfert type of active galactic nuclei (AGNs). Moreover, we examined the radius-luminosity correlations for the hard X-ray (14-195 keV) and the [O IV] ?25.89 ?m emission-line luminosities, which would be applicable for obscured AGNs.
Osmotic buckling of spherical capsules Sebastian Knoche and Jan Kierfeld*
Kierfeld, Jan
Osmotic buckling of spherical capsules Sebastian Knoche and Jan Kierfeld* We study the buckling of elastic spherical shells under osmotic pressure with the osmolyte concentration of the exterior solution for the buckling states between osmotic and mechanical buckling. Mechanical pressure control always leads to fully
The Concept of Collapsed Electrodes for Glassblown Spherical Resonators Demonstrating
Chen, Zhongping
-spherical structures using micro glass-blowing techniques [10], demonstrating low order resonant frequencies about 1MHzHz [4]. Plastic deformation of metallic glasses to achieve spherical structures has been explored by using a blow-molding technique [5]. The use of low Thermo-Elastic Damping (TED) materials, such as Fused
Orthogonal fast spherical Bessel transform on uniform grid
Serov, Vladislav V
2015-01-01
We propose an algorithm for the orthogonal fast discrete spherical Bessel transform on an uniform grid. Our approach is based upon the spherical Bessel transform factorization into the two subsequent orthogonal transforms, namely the fast Fourier transform and the orthogonal transform founded on the derivatives of the discrete Legendre orthogonal polynomials.
Photonic crystals Fabrication of Tunable Spherical Colloidal Crystals
Photonic crystals Fabrication of Tunable Spherical Colloidal Crystals Immobilized in Soft Hydrogels** Toshimitsu Kanai, Daeyeon Lee, Ho Cheung Shum, and David A. Weitz* Spherical colloidal crystals are three as photonic crystals in the optical regime.[2] In contrast to conventional film-type colloidal crystals where
Spectral asymmetry of the massless Dirac operator on a 3-torus
Downes, Robert J., E-mail: R.Downes@ucl.ac.uk; Vassiliev, Dmitri, E-mail: D.Vassiliev@ucl.ac.uk [Department of Mathematics, University College London, Gower Street, London WC1E 6BT (United Kingdom)] [Department of Mathematics, University College London, Gower Street, London WC1E 6BT (United Kingdom); Levitin, Michael, E-mail: M.Levitin@reading.ac.uk [Department of Mathematics and Statistics, University of Reading, Whiteknights, PO Box 220, Reading RG6 6AX (United Kingdom)] [Department of Mathematics and Statistics, University of Reading, Whiteknights, PO Box 220, Reading RG6 6AX (United Kingdom)
2013-11-15
Consider the massless Dirac operator on a 3-torus equipped with Euclidean metric and standard spin structure. It is known that the eigenvalues can be calculated explicitly: the spectrum is symmetric about zero and zero itself is a double eigenvalue. The aim of the paper is to develop a perturbation theory for the eigenvalue with smallest modulus with respect to perturbations of the metric. Here the application of perturbation techniques is hindered by the fact that eigenvalues of the massless Dirac operator have even multiplicity, which is a consequence of this operator commuting with the antilinear operator of charge conjugation (a peculiar feature of dimension 3). We derive an asymptotic formula for the eigenvalue with smallest modulus for arbitrary perturbations of the metric and present two particular families of Riemannian metrics for which the eigenvalue with smallest modulus can be evaluated explicitly. We also establish a relation between our asymptotic formula and the eta invariant.
Compact Torus Accelerator Driven Inertial Confinement Fusion Power Plant HYLIFE-CT
Logan, B G; Moir, R W; Tabak, M; Bieri, R L; Hammer, J H; Hartman, C W; Hoffman, M A; Leber, R L; Petzoldt, R W; Tobin, M T
2005-03-30
A Compact Torus Accelerator (CTA) is used to accelerate a Compact Torus (CT) to 35 MJ kinetic energy which is focused to a 20 mm diameter where its kinetic energy is converted to a shaped x-ray pulse of 30 MJ. The capsule yield with a prescribed radiation profile is calculated to be (gain 60 times 30 MJ) 1.8 GJ. Schemes for achieving this profile are described. The CT is accelerated in a length of 30 m within an annulus of 150 mm ID and 300 mm OD where the maximum magnetic field is 28 T. A 2.5 m conical taper reduces the mean diameter of the CT from 225 mm to 20 mm. The conical section is made out of solid Li{sub 2}BeF{sub 4}. The target with its frozen conical guide section is accurately placed at the end of the accelerator about once per second. The reactor called HYLIFE uses liquid jets to attenuate blast effects including shrapnel from the shattered conical guide section and radiation so that the vessel is expected to last 30 years. The calculated cost of electricity is estimated (in constant 1988 dollars) to be about 4.8 cents/kW {center_dot} h compared to the future cost of nuclear and coal of 4.3 to 5.8 cents/kW {center_dot} h. The CT driver contributes 17% to the cost of electricity. Present CT's make 2 x 10{sup 8} W/cm{sup 2}; the goal of experiments in progress is 10{sup 11} W/cm{sup 2} with further modifications to allow 10{sup 12}W/cm{sup 2}, whereas the reactor requires 10{sup 15} W/cm{sup 2} in a shaped pulse.
High-frequency propagation for the Schroedinger equation on the torus
Fabricio Macia
2009-10-07
The main objective of this paper is understanding the propagation laws obeyed by high-frequency limits of Wigner distributions associated to solutions to the Schroedinger equation on the standard d-dimensional torus T^{d}. From the point of view of semiclassical analysis, our setting corresponds to performing the semiclassical limit at times of order 1/h, as the characteristic wave-length h of the initial data tends to zero. It turns out that, in spite that for fixed h every Wigner distribution satisfies a Liouville equation, their limits are no longer uniquely determined by those of the Wigner distributions of the initial data. We characterize them in terms of a new object, the resonant Wigner distribution, which describes high-frequency effects associated to the fraction of the energy of the sequence of initial data that concentrates around the set of resonant frequencies in phase-space T^{*}T^{d}. This construction is related to that of the so-called two-microlocal semiclassical measures. We prove that any limit \\mu of the Wigner distributions corresponding to solutions to the Schroedinger equation on the torus is completely determined by the limits of both the Wigner distribution and the resonant Wigner distribution of the initial data; moreover, \\mu follows a propagation law described by a family of density-matrix Schroedinger equations on the periodic geodesics of T^{d}. Finally, we present some connections with the study of the dispersive behavior of the Schroedinger flow (in particular, with Strichartz estimates). Among these, we show that the limits of sequences of position densities of solutions to the Schroedinger equation on T^2 are absolutely continuous with respect to the Lebesgue measure.
Some improvements to the spherical collapse model
Antonino Del Popolo
2008-01-07
I study the joint effect of dynamical friction, tidal torques and cosmological constant on clusters of galaxies formation I show that within high-density environments, such as rich clusters of galaxies, both dynamical friction and tidal torques slows down the collapse of low-? peaks producing an observable variation in the time of collapse of the perturbation and, as a consequence, a reduction in the mass bound to the collapsed perturbation Moreover, the delay of the collapse produces a tendency for less dense regions to accrete less mass, with respect to a classical spherical model, inducing a biasing of over-dense regions toward higher mass I show how the threshold of collapse is modified if dynamical friction, tidal torques and a non-zero cosmological constant are taken into account and I use the Extended Press Schecter (EPS) approach to calculate the effects on the mass function Then, I compare the numerical mass function given in Reed et al (2003) with the theoretical mass function obtained in the present paper I show that the barrier obtained in the present paper gives rise to a better description of the mass function evolution with respect to other previous models (Sheth & Tormen 1999, MNRAS, 308, 119 (hereafter ST); Sheth & Tormen 2002, MNRAS, 329, 61 (hereafter ST1))
Spherical nanoindentation stress–strain curves
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Pathak, Siddhartha; Kalidindi, Surya R.
2015-03-24
Although indentation experiments have long been used to measure the hardness and Young's modulus, the utility of this technique in analyzing the complete elastic–plastic response of materials under contact loading has only been realized in the past few years – mostly due to recent advances in testing equipment and analysis protocols. This paper provides a timely review of the recent progress made in this respect in extracting meaningful indentation stress–strain curves from the raw datasets measured in instrumented spherical nanoindentation experiments. These indentation stress–strain curves have produced highly reliable estimates of the indentation modulus and the indentation yield strength inmore »the sample, as well as certain aspects of their post-yield behavior, and have been critically validated through numerical simulations using finite element models as well as direct in situ scanning electron microscopy (SEM) measurements on micro-pillars. Much of this recent progress was made possible through the introduction of a new measure of indentation strain and the development of new protocols to locate the effective zero-point of initial contact between the indenter and the sample in the measured datasets. As a result, this has led to an important key advance in this field where it is now possible to reliably identify and analyze the initial loading segment in the indentation experiments.« less
Spherical nanoindentation stress–strain curves
Pathak, Siddhartha; Kalidindi, Surya R.
2015-03-24
Although indentation experiments have long been used to measure the hardness and Young's modulus, the utility of this technique in analyzing the complete elastic–plastic response of materials under contact loading has only been realized in the past few years – mostly due to recent advances in testing equipment and analysis protocols. This paper provides a timely review of the recent progress made in this respect in extracting meaningful indentation stress–strain curves from the raw datasets measured in instrumented spherical nanoindentation experiments. These indentation stress–strain curves have produced highly reliable estimates of the indentation modulus and the indentation yield strength in the sample, as well as certain aspects of their post-yield behavior, and have been critically validated through numerical simulations using finite element models as well as direct in situ scanning electron microscopy (SEM) measurements on micro-pillars. Much of this recent progress was made possible through the introduction of a new measure of indentation strain and the development of new protocols to locate the effective zero-point of initial contact between the indenter and the sample in the measured datasets. As a result, this has led to an important key advance in this field where it is now possible to reliably identify and analyze the initial loading segment in the indentation experiments.
Spherical rotary valve assembly for an internal combustion engine
Coates, G.J.
1991-02-05
This patent describes an improved rotary intake valve for use in a rotary valved internal combustion engine. It comprises: a drum body of spherical section formed by two parallel planar side walls of a sphere disposed about a center thereof thereby defining a spherically-shaped end wall and formed with a shaft receiving aperture, the drum body formed with a circularly-shaped cavity in a side wall thereof and with a channel extending between the circularly-shaped cavity and an aperture formed in the spherically-shaped end wall.
Spherical gravitational collapse in N dimensions
Goswami, Rituparno; Joshi, Pankaj S.
2007-10-15
We investigate here spherically symmetric gravitational collapse in a space-time with an arbitrary number of dimensions and with a general type I matter field, which is a broad class that includes most of the physically reasonable matter forms. We show that given the initial data for matter in terms of the initial density and pressure profiles at an initial surface t=t{sub i} from which the collapse evolves, there exist the rest of the initial data functions and classes of solutions of Einstein equations which we construct here, such that the space-time evolution goes to a final state which is either a black hole or a naked singularity, depending on the nature of initial data and evolutions chosen, and subject to validity of the weak energy condition. The results are discussed and analyzed in the light of the cosmic censorship hypothesis in black hole physics. The formalism here combines the earlier results on gravitational collapse in four dimensions in a unified treatment. Also the earlier work is generalized to higher-dimensional space-times to allow a study of the effect of the number of dimensions on the possible final outcome of the collapse in terms of either a black hole or naked singularity. No restriction is adopted on the number of dimensions, and other limiting assumptions such as self-similarity of space-time are avoided, in order to keep the treatment general. Our methodology allows us to consider to an extent the genericity and stability aspects related to the occurrence of naked singularities in gravitational collapse.
Marc Briant
2015-07-11
We investigate the Boltzmann equation, depending on the Knudsen number, in the Navier-Stokes perturbative setting on the torus. Using hypocoercivity, we derive a new proof of existence and exponential decay for solutions close to a global equilibrium, with explicit regularity bounds and rates of convergence. These results are uniform in the Knudsen number and thus allow us to obtain a strong derivation of the incompressible Navier-Stokes equations as the Knudsen number tends to $0$. Moreover, our method is also used to deal with other kinetic models. Finally, we show that the study of the hydrodynamical limit is rather different on the torus than the one already proved in the whole space as it requires averaging in time, unless the initial layer conditions are satisfied.
Stephan Gekle; Jörg Main; Thomas Bartsch; T. Uzer
2006-10-02
A hierarchical ordering is demonstrated for the periodic orbits in a strongly coupled multidimensional Hamiltonian system, namely the hydrogen atom in crossed electric and magnetic fields. It mirrors the hierarchy of broken resonant tori and thereby allows one to characterize the periodic orbits by a set of winding numbers. With this knowledge, we construct the action variables as functions of the frequency ratios and carry out a semiclassical torus quantization. The semiclassical energy levels thus obtained agree well with exact quantum calculations.
Zuccarello, F. P.; Poedts, S.; Seaton, D. B.; Mierla, M.; Rachmeler, L. A.; Romano, P.; Zuccarello, F. E-mail: Stefaan.Poedts@wis.kuleuven.be E-mail: marilena@oma.be E-mail: Paolo.Romano@oact.inaf.it
2014-04-20
Solar filaments are magnetic structures often observed in the solar atmosphere and consist of plasma that is cooler and denser than their surroundings. They are visible for days—even weeks—which suggests that they are often in equilibrium with their environment before disappearing or erupting. Several eruption models have been proposed that aim to reveal what mechanism causes (or triggers) these solar eruptions. Validating these models through observations represents a fundamental step in our understanding of solar eruptions. We present an analysis of the observation of a filament eruption that agrees with the torus instability model. This model predicts that a magnetic flux rope embedded in an ambient field undergoes an eruption when the axis of the flux rope reaches a critical height that depends on the topology of the ambient field. We use the two vantage points of the Solar Dynamics Observatory (SDO) and the Solar TErrestrial RElations Observatory to reconstruct the three-dimensional shape of the filament, to follow its morphological evolution, and to determine its height just before eruption. The magnetograms acquired by SDO/Helioseismic and Magnetic Imager are used to infer the topology of the ambient field and to derive the critical height for the onset of the torus instability. Our analysis shows that the torus instability is the trigger of the eruption. We also find that some pre-eruptive processes, such as magnetic reconnection during the observed flares and flux cancellation at the neutral line, facilitated the eruption by bringing the filament to a region where the magnetic field was more vulnerable to the torus instability.
Elastic–Plastic Spherical Contact Modeling Including Roughness Effects
Li, L.; Etsion, I.; Talke, F. E.
2010-01-01
A multilevel model for elastic–plastic contact between ajunction growth of an elastic–plastic spherical contact. J.nite element based elastic–plastic model for the contact of
Design, construction and implementation of spherical tissue equivalent proportional counter
Perez Nunez, Delia Josefina
2009-05-15
and the response to neutrons as a function of angle was constant ±7%. This spherical tissue equivalent proportional counter detector system will improve the accuracy of dosimetry in space, and as a result improve radiation safety for astronauts....
X-ray interferometry with spherically bent crystals (abstract)
Koch, Jeffrey A.
2001-01-01
Recent progress in manufacturing high-quality spherically bent crystals allows highly monochromatic x-ray beams to be produced, and allows efficient x-ray imaging with {mu}m-scale resolution. This article explores some of the constraints for x-ray interferometry utilizing spherically bent crystals and laser-produced plasma sources, and discusses several shearing interferometer concepts that might be experimentally investigated.
An axisymmetric hydrodynamical model for the torus wind in AGN. II: X-ray excited funnel flow
Dorodnitsyn, A; Proga, D
2008-01-01
We have calculated a series of models of outflows from the obscuring torus in active galactic nuclei (AGN). Our modeling assumes that the inner face of a rotationally supported torus is illuminated and heated by the intense X-rays from the inner accretion disk and black hole. As a result of such heating a strong biconical outflow is observed in our simulations. We calculate 3-dimensional hydrodynamical models, assuming axial symmetry, and including the effects of X-ray heating, ionization, and radiation pressure. We discuss the behavior of a large family of these models, their velocity fields, mass fluxes and temperature, as functions of the torus properties and X-ray flux. Synthetic warm absorber spectra are calculated, assuming pure absorption, for sample models at various inclination angles and observing times. We show that these models have mass fluxes and flow speeds which are comparable to those which have been inferred from observations of Seyfert 1 warm absorbers, and that they can produce rich absorp...
An axisymmetric hydrodynamical model for the torus wind in AGN. II: X-ray excited funnel flow
A. Dorodnitsyn; T. Kallman; D. Proga
2008-06-23
We have calculated a series of models of outflows from the obscuring torus in active galactic nuclei (AGN). Our modeling assumes that the inner face of a rotationally supported torus is illuminated and heated by the intense X-rays from the inner accretion disk and black hole. As a result of such heating a strong biconical outflow is observed in our simulations. We calculate 3-dimensional hydrodynamical models, assuming axial symmetry, and including the effects of X-ray heating, ionization, and radiation pressure. We discuss the behavior of a large family of these models, their velocity fields, mass fluxes and temperature, as functions of the torus properties and X-ray flux. Synthetic warm absorber spectra are calculated, assuming pure absorption, for sample models at various inclination angles and observing times. We show that these models have mass fluxes and flow speeds which are comparable to those which have been inferred from observations of Seyfert 1 warm absorbers, and that they can produce rich absorption line spectra.
Janiuk, Agnieszka; Mioduszewski, Patryk [Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Moscibrodzka, Monika, E-mail: agnes@cft.edu.pl [Department of Physics, University of Nevada Las Vegas, 4505 South Maryland Parkway, Las Vegas, NV 89154 (United States)
2013-10-20
We calculate the structure and short-term evolution of a gamma-ray burst (GRB) central engine in the form of a turbulent torus accreting onto a stellar mass black hole. Our models apply to the short GRB events, in which a remnant torus forms after the neutron star-black hole or a double neutron star merger and is subsequently accreted. We study the two-dimensional, relativistic models and concentrate on the effects of the black hole and flow parameters as well as the neutrino cooling. We compare the resulting structure and neutrino emission to the results of our previous one-dimensional simulations. We find that the neutrino cooled torus launches a powerful mass outflow, which contributes to the total neutrino luminosity and mass loss from the system. The neutrino luminosity may exceed the Blandford-Znajek luminosity of the polar jets and the subsequent annihilation of neutrino-antineutrino pairs will provide an additional source of power to the GRB emission.
Villone, F.; Mastrostefano, S. [Euratom-ENEA-CREATE Ass., DIEI, Univ. di Cassino e Lazio Merid., Cassino (Italy); Calabrò, G.; Vlad, G.; Crisanti, F.; Fusco, V. [C. R. Frascati, Euratom-ENEA Ass., Via E. Fermi 45, 00044 Frascati (Italy); Marchiori, G.; Bolzonella, T.; Marrelli, L.; Martin, P. [Cons. RFX, Euratom-ENEA-RFX Ass., Corso Stati Uniti 4, 35127 Padova (Italy); Liu, Y. Q. [Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Mantica, P. [IFP-CNR, Euratom-ENEA-CNR Ass. Via Cozzi 53, 20125 Milano (Italy)
2014-08-15
One of the main FAST (Fusion Advanced Studies Torus) goals is to have a flexible experiment capable to test tools and scenarios for safe and reliable tokamak operation, in order to support ITER and help the final DEMO design. In particular, in this paper, we focus on operation close to a possible border of stability related to low-q operation. To this purpose, a new FAST scenario has then been designed at I{sub p}?=?10 MA, B{sub T}?=?8.5?T, q{sub 95}???2.3. Transport simulations, carried out by using the code JETTO and the first principle transport model GLF23, indicate that, under these conditions, FAST could achieve an equivalent Q???3.5. FAST will be equipped with a set of internal active coils for feedback control, which will produce magnetic perturbation with toroidal number n?=?1 or n?=?2. Magnetohydrodynamic (MHD) mode analysis and feedback control simulations performed with the codes MARS, MARS-F, CarMa (both assuming the presence of a perfect conductive wall and using the exact 3D resistive wall structure) show the possibility of the FAST conductive structures to stabilize n?=?1 ideal modes. This leaves therefore room for active mitigation of the resistive mode (down to a characteristic time of 1?ms) for safety purposes, i.e., to avoid dangerous MHD-driven plasma disruption, when working close to the machine limits and magnetic and kinetic energy density not far from reactor values.
Frequency-Sweeping Alfvén Instabilities Driven by Super-Alfvénic Beams in the Spherical Tokamak START
Method to produce large, uniform hollow spherical shells
Hendricks, C.D.
1983-09-26
The invention is a method to produce large uniform hollow spherical shells by (1) forming uniform size drops of heat decomposable or vaporizable material, (2) evaporating the drops to form dried particles, (3) coating the dried particles with a layer of shell forming material and (4) heating the composite particles to melt the outer layer and to decompose or vaporize the inner particle to form an expanding inner gas bubble. The expanding gas bubble forms the molten outer layer into a shell of relatively large diameter. By cycling the temperature and pressure on the molten shell, nonuniformities in wall thickness can be reduced. The method of the invention is utilized to produce large uniform spherical shells, in the millimeter to centimeter diameter size range, from a variety of materials and of high quality, including sphericity, concentricity and surface smoothness, for use as laser fusion or other inertial confinement fusion targets as well as other applications.
CHARACTERIZATION OF CYCLED SPHERICAL RESORCINOL-FORMALDEHYDE ION EXCHANGE RESIN
Nash, C.; Duignan, M.
2010-02-23
This report presents characterization data for two spherical resorcinol-formaldehyde (sRF) resin beds that had processed cesium in non-radioactive and radioactive cycles. All column cycle operations for the resin beds including loading, displacements, elution, regeneration, breakthroughs, and solution analyses are reported in Nash and Duignan, 2009a. That report covered four ion exchange (IX) campaigns using the two {approx}11 mL beds in columns in a lead-lag arrangement. The first two campaigns used Savannah River Site (SRS) Tank 2F nonradioactive simulant while the latter two were fed with actual dissolved salt in the Savannah River National Laboratory (SRNL) Shielded Cells. Both radioactive cycles ran to cesium breakthrough of the lead column. The resin beds saw in excess of 400 bed volumes of feed in each cycle. Resin disposal plans in tank farm processing depend on characterizations of resin used with actual tank feed. Following a final 30 bed volume (BV) elution with nitric acid, the resin beds were found to contain detectable chromium, barium, boron, aluminum, iron, sodium, sulfur, plutonium, cesium, and mercury. Resin affinity for plutonium is important in criticality safety considerations. Cesium-137 was found to be less than 10E+7 dpm/g of resin, similar to past work with sRF resin. Sulfur levels are reasonably consistent with other work and are expected to represent sulfur chemistry used in the resin manufacture. There were low but detectable levels of technetium, americium, and curium. Toxicity Characteristic Leaching Procedure (TCLP) work on the used (eluted) resin samples showed significant contents of mercury, barium, and chromium. One resin sample exceeded the TCLP level for mercury while the other metals were below TCLP levels. TCLP organics measurements indicated measurable benzene in one case, though the source was unknown. Results of this work were compared with other work on similar sRF resin characterizations in this report. This is the first work to quantify mercury on sRF resin. Resin mercury content is important in plans for the disposition of used sRF resin. Mercury speciation in high level waste (HLW) is unknown. It may be partly organic, one example being methyl mercury cation. Further study of the resin's affinity for mercury is recommended.
Spherical cloaking using multilayer shells of ordinary dielectrics
Wang, Xiaohui; Chen, Fang; Semouchkina, Elena, E-mail: esemouch@mtu.edu [Department of Electrical and Computer Engineering, Michigan Technological University, Houghton, MI, 49931 (United States)] [Department of Electrical and Computer Engineering, Michigan Technological University, Houghton, MI, 49931 (United States)
2013-11-15
An approach for spherical cloaking using multilayer ordinary dielectric materials has been developed. The total scattering cross section (TSCS) of the spherical multilayer shell with metallic core was derived based on the Mie theory. The dielectric profile of the shell was optimized to minimize the TSCS of the cloaked target. The specific directions, at which the scattering could be practically eliminated, were detected. The influence of the target size and the dielectric material loss on the cloaking efficiency was analyzed. It was shown that the cloaking efficiency for larger targets could be improved by employing lossy materials in the shell.
The analysis and optimization of a spherical silicon solar cell
McKee, William Randall
1976-01-01
THE ANALYSIS AND OPTIMIZATION OF A SPHERICAL SILICON SOLAR CELL A Thesis by William Randall McKee /'' Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE... August 1976 Ma]or Subject: Electrical Engineering THE ANALYSIS AND OPTIMIZATION OF A SPHERICAL SILICON SOLAR CELL A Thesis by William Randall McKee Approved as to style and content by: (Chai. rman of Committee) (H of D partment) (Member) 2D...
Quantum nonlocal effects on optical properties of spherical nanoparticles
Moradi, Afshin
2015-02-15
To study the scattering of electromagnetic radiation by a spherical metallic nanoparticle with quantum spatial dispersion, we develop the standard nonlocal Mie theory by allowing for the excitation of the quantum longitudinal plasmon modes. To describe the quantum nonlocal effects, we use the quantum longitudinal dielectric function of the system. As in the standard Mie theory, the electromagnetic fields are expanded in terms of spherical vector wavefunctions. Then, the usual Maxwell boundary conditions are imposed plus the appropriate additional boundary conditions. Examples of calculated extinction spectra are presented, and it is found that the frequencies of the subsidiary peaks, due to quantum bulk plasmon excitations exhibit strong dependence on the quantum spatial dispersion.
Chen, Dong; Coteus, Paul W; Eisley, Noel A; Gara, Alan; Heidelberger, Philip; Senger, Robert M; Salapura, Valentina; Steinmacher-Burow, Burkhard; Sugawara, Yutaka; Takken, Todd E
2013-08-27
Embodiments of the invention provide a method, system and computer program product for embedding a global barrier and global interrupt network in a parallel computer system organized as a torus network. The computer system includes a multitude of nodes. In one embodiment, the method comprises taking inputs from a set of receivers of the nodes, dividing the inputs from the receivers into a plurality of classes, combining the inputs of each of the classes to obtain a result, and sending said result to a set of senders of the nodes. Embodiments of the invention provide a method, system and computer program product for embedding a collective network in a parallel computer system organized as a torus network. In one embodiment, the method comprises adding to a torus network a central collective logic to route messages among at least a group of nodes in a tree structure.
Dynamics of multiple double layers in high pressure glow discharge in a simple torus
Kumar Paul, Manash, E-mail: manashkr@gmail.com [Department of Physics, National Institute of Technology Agartala, Tripura–799 046 (India); Sharma, P. K.; Thakur, A.; Kulkarni, S. V.; Bora, D. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat–382 428 (India)
2014-06-15
Parametric characterization of multiple double layers is done during high pressure glow discharge in a toroidal vessel of small aspect ratio. Although glow discharge (without magnetic field) is known to be independent of device geometry, but the toroidal boundary conditions are conducive to plasma growth and eventually the plasma occupy the toroidal volume partially. At higher anode potential, the visibly glowing spots on the body of spatially extended anode transform into multiple intensely luminous spherical plasma blob structures attached to the tip of the positive electrode. Dynamics of multiple double layers are observed in argon glow discharge plasma in presence of toroidal magnetic field. The radial profiles of plasma parameters measured at various toroidal locations show signatures of double layer formation in our system. Parametric dependence of double layer dynamics in presence of toroidal magnetic field is presented here.
Naked Singularities in Spherically Symmetric, Self-Similar Spacetimes
Sanjay M. Wagh; Keshlan S. Govinder
2001-12-24
We show that all known naked singularities in spherically symmetric self-similar spacetimes arise as a result of singular initial matter distribution. This is a result of the peculiarity of the coordinate transformation that takes these spacetimes into a separable form. Therefore, these examples of naked singularities are of no apparent consequence to astrophysical observations or theories.
Water adsorption on aggregates of spherical aerosol nano particles
Nie, Chu
2005-11-01
, )12(B ),,,,,()12( 21122112 ???? ?= rXX (2.75) A spherical harmonic expansion of the correlation functions is like * 2 ~ * 1212 2 1 21 )()()()]12)(12[()12( 2 2 1 1 2121 21 21 ?? l nm l mn nmnll nn mll DDr...
The method of planes pressure tensor for a spherical subvolume
Heyes, D. M., E-mail: d.heyes@imperial.ac.uk; Smith, E. R., E-mail: edward.smith05@imperial.ac.uk; Dini, D., E-mail: d.dini@imperial.ac.uk; Zaki, T. A., E-mail: t.zaki@imperial.ac.uk [Department of Mechanical Engineering, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ (United Kingdom)
2014-02-07
Various formulas for the local pressure tensor based on a spherical subvolume of radius, R, are considered. An extension of the Method of Planes (MOP) formula of Todd et al. [Phys. Rev. E 52, 1627 (1995)] for a spherical geometry is derived using the recently proposed Control Volume formulation [E. R. Smith, D. M. Heyes, D. Dini, and T. A. Zaki, Phys. Rev. E 85, 056705 (2012)]. The MOP formula for the purely radial component of the pressure tensor is shown to be mathematically identical to the Radial Irving-Kirkwood formula. Novel offdiagonal elements which are important for momentum conservation emerge naturally from this treatment. The local pressure tensor formulas for a plane are shown to be the large radius limits of those for spherical surfaces. The radial-dependence of the pressure tensor computed by Molecular Dynamics simulation is reported for virtual spheres in a model bulk liquid where the sphere is positioned randomly or whose center is also that of a molecule in the liquid. The probability distributions of angles relating to pairs of atoms which cross the surface of the sphere, and the center of the sphere, are presented as a function of R. The variance in the shear stress calculated from the spherical Volume Averaging method is shown to converge slowly to the limiting values with increasing radius, and to be a strong function of the number of molecules in the simulation cell.
Separating expansion from contraction and generalizing TOV condition in spherically
Paris-Sud XI, UniversitÃ© de
example of perturbed -CDM models. We adopt the Generalised PainlevÃ©-Gullstrand (hereafter GPG) formalism invariants kinematic quantities [6]. ADM APPROACH TO LTB MODELS IN GPG SYSTEM We consider a spherically. Performing an ADM 3+1 splitting in the GPG coordinates [5] , the metric reads ds2 = -(t,r)2 dt2 + 1 1+E
Novel spherical hohlraum with cylindrical laser entrance holes and shields
Lan, Ke [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Zheng, Wudi [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)
2014-09-15
Our recent works [K. Lan et al., Phys. Plasmas 21, 010704 (2014); K. Lan et al., Phys. Plasmas 21, 052704 (2014)] have shown that the octahedral spherical hohlraums are superior to the cylindrical hohlraums in both higher symmetry during the capsule implosion and lower backscatter without supplementary technology. However, both the coupling efficiency from the drive laser energy to the capsule and the capsule symmetry decrease remarkably when larger laser entrance holes (LEHs) are used. In addition, the laser beams injected at angles?>?45° transport close to the hohlraum wall, thus the wall blowoff causes the LEH to close faster and results in strong laser plasma interactions inside the spherical hohlraums. In this letter, we propose a novel octahedral hohlraum with LEH shields and cylindrical LEHs to alleviate these problems. From our theoretical study, with the LEH shields, the laser coupling efficiency is significantly increased and the capsule symmetry is remarkably improved in the spherical hohlraums. The cylindrical LEHs take advantage of the cylindrical hohlraum near the LEH and mitigate the influence of the blowoff on laser transport inside a spherical hohlraum. The cylindrical LEHs can also be applied to the rugby and elliptical hohlraums.
The Complete Flux Scheme for Spherically Symmetric Conservation Laws
Eindhoven, Technische Universiteit
and M.J.H. Anthonissen Eindhoven University of Technology Department of Mathematics and Computer Science for computing the numerical fluxes. The approximation for the flux is based on the complete differential to a spherically symmet- ric conservation law of advection-diffusion-reaction type. For the numer- ical flux we use
[1] Yao, K. Spherically invariant random processes: Theory and
Nehorai, Arye
), 1453--1457. [11] Kay, S. M. Fundamental of Statistical Signal Processing: Esimation Theory. PrenticeREFERENCES [1] Yao, K. Spherically invariant random processes: Theory and applications. In V. K) bound, we analyze the performance of different array configurations, which include an electromagnetic
Stability and superluminality of spherical DBI Galileon solutions
Goon, Garrett L.; Hinterbichler, Kurt; Trodden, Mark
2011-04-12
We showed that, when considered as local modifications to gravity, such as in the solar system, there exists a region of parameter space in which spherically symmetric static solutions to a particular class of modified gravity theories exist and are stable.
Multivariate Tests Based on Left-Spherically Distributed Linear Scores
Magdeburg, UniversitÃ¤t
Multivariate Tests Based on Left-Spherically Distributed Linear In this paper, a method for multivariate testing based on low-dimensional, data- dependent, linear scores approaches. In a natural way, standard problems of multivari- ate analysis thus induce the occurrence
Anvil effect in spherical indentation testing on sheet metal
Dhaigude, Mayuresh Mukund
2009-06-02
A spherical indentation test is considered to be invalid if there is presence of a visible mark on the side of the sheet metal facing the anvil and exactly below the indentation. With the available standard loads of the conventional testers...
ABAREX: A neutron spherical optical-statistical model code
Lawson, R.D.
1992-06-01
The spherical optical-statistical model is briefly reviewed and the capabilities of the neutron scattering code, ABAREX, are presented. Input files for ten examples, in which neutrons are scattered by various nuclei, are given and the output of each run is discussed in detail.
Spherical Domain Wall Collapse in a Dust Universe
Norihiro Tanahashi; Chul-Moon Yoo
2015-05-13
To clarify observational consequence of bubble nucleations in inflationary era, we analyse dynamics of a spherical domain wall in an expanding universe. We consider a spherical shell of the domain wall with tension $\\sigma$ collapsing in a spherically-symmetric dust universe, which is initially separated into the open Friedmann-Lema\\^itre-Robertson-Walker universe inside the shell and the Einstein-de Sitter universe outside. The domain wall shell collapses due to the tension, and sweeps the dust fluid. The universe after the collapse becomes inhomogeneous and is described by the Lema\\^itre-Tolman-Bondi model. We construct solutions describing this inhomogeneous universe by solving dynamical equations obtained from Israel's junction conditions applied to this system. We find that a black hole forms after the domain wall collapse for any initial condition, and that the black hole mass at the moment of its formation is universally given by $M_{\\rm BH}\\simeq 17 \\sigma/H_{\\rm hc}$, where $H_{\\rm hc}$ is the Hubble parameter at the time when the shell radius becomes equal to the Hubble radius. We also find that the dust fluid is distributed as $\\rho\\propto R^{3/2}$ near the central region after the collapse, where $R$ is the area radius. These features would provide observable signatures of a spherical domain wall generated in the early universe.
Wilkinson, Michael
for Quantum Chaos on a Torus Itzhack Dana,1 Mario Feingold,2 and Michael Wilkinson3 1 Department of Physics in the field of quantum chaos, can be reduced to a torus, either in configuration space (e.g., the Sinai in the quantum-chaos literature [4Â12], although attention has often been confined to strict periodicity. General
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Ghoshal, P. K.; Pastor, O.; Kashy, D.; Schneider, W.; Wiseman, M.; Zarecky, M.; Young, G.; Rode, C.; Elouadrhiri, L.; Burkert, V.
2014-12-18
The torus magnet for the CLAS12 spectrometer is a 3.6 T superconducting magnet being designed and built as part of the Jefferson Lab 12 GeV Upgrade. The magnet consists of six coil case assemblies mounted to a cold central hub. The coil case assembly consists of an aluminum case and cover enclosing an epoxy vacuum impregnated coil pack. The coil pack consists of a 117 turn double-pancake winding wrapped with 2 layers of 0.635 mm thick copper cooling sheets. The coil case assembly is cooled by supercritical helium at 4.6 K. This report details the structural analysis of the coilmore »case assembly and the assessment of the coil pack stresses. For the normal operation of the torus magnet, the coil case assembly was analyzed for cool down to 4.6 K and the Lorentz forces at normal operating current. In addition to the normal operating configuration, the coil case assembly was analyzed for Lorentz forces arising from coil misalignment and current imbalances. The allowable stress criteria for the magnet followed the approach of the ASME codes. Primary stresses were limited to the lesser of 2/3 times the yield strength or 1/3 times the ultimate tensile strength. Primary plus secondary stresses were limited to 3 times the primary stress allowable. The analysis was performed using ANSYS Maxwell to calculate the magneto-static loads and ANSYS Mechanical to calculate the stresses.« less
Ghoshal, P. K.; Pastor, O.; Kashy, D.; Schneider, W.; Wiseman, M.; Zarecky, M.; Young, G.; Rode, C.; Elouadrhiri, L.; Burkert, V.
2014-12-18
The torus magnet for the CLAS12 spectrometer is a 3.6 T superconducting magnet being designed and built as part of the Jefferson Lab 12 GeV Upgrade. The magnet consists of six coil case assemblies mounted to a cold central hub. The coil case assembly consists of an aluminum case and cover enclosing an epoxy vacuum impregnated coil pack. The coil pack consists of a 117 turn double-pancake winding wrapped with 2 layers of 0.635 mm thick copper cooling sheets. The coil case assembly is cooled by supercritical helium at 4.6 K. This report details the structural analysis of the coil case assembly and the assessment of the coil pack stresses. For the normal operation of the torus magnet, the coil case assembly was analyzed for cool down to 4.6 K and the Lorentz forces at normal operating current. In addition to the normal operating configuration, the coil case assembly was analyzed for Lorentz forces arising from coil misalignment and current imbalances. The allowable stress criteria for the magnet followed the approach of the ASME codes. Primary stresses were limited to the lesser of 2/3 times the yield strength or 1/3 times the ultimate tensile strength. Primary plus secondary stresses were limited to 3 times the primary stress allowable. The analysis was performed using ANSYS Maxwell to calculate the magneto-static loads and ANSYS Mechanical to calculate the stresses.
Etheridge, A M
2011-01-01
We extend the spatial Lambda-Fleming-Viot process introduced in [BEV10] to incorporate recombination. The process models allele frequencies in a population which is distributed over the two-dimensional torus T(L) of sidelength L and is subject to two kinds of reproduction events : small events of radius O(1) and much rarer large events of radius O(L^{alpha}) for some alpha in (0,1]. We investigate the correlation between the times to the most recent common ancestor of alleles at two linked loci for a sample of size two from the population. These individuals are initially sampled from `far apart' on the torus. As L tends to infinity, depending on the frequency of the large events, the recombination rate and the initial distance between the two individuals sampled, we obtain either a complete decorrelation of the coalescence times at the two loci, or a sharp transition between a first period of complete correlation and a subsequent period during which the remaining times needed to reach the most recent common a...
Masao Iwamatsu
2015-06-19
Line-tension-induced {scenario of heterogeneous nucleation} is studied for a lens-shaped nucleus with a finite contact angle nucleated on a spherical substrate and on the bottom of the wall of a spherical cavity. The effect of line tension on the free energy of a critical nucleus can be separated from the usual volume term. By comparing the free energy of a lens-shaped critical nucleus of a finite contact angle with that of a spherical nucleus, we find that a spherical nucleus may have a lower free energy than a lens-shaped nucleus when the line tension is positive and large, which is similar to the drying transition predicted by Widom [B. Widom, J. Phys. Chem. {\\bf 99} 2803 (1995)]. Then, the homogeneous nucleation rather than the heterogeneous nucleation will be favorable. Similarly, the free energy of a lens-shaped nucleus becomes negative when the line tension is negative and large. Then, the barrier-less nucleation with no thermal activation called athermal nucleation will be realized.
Analysis, Design, and Operation of a Spherical Inverted-F Antenna
McDonald, Jacob J.
2010-07-14
This thesis presents the analysis, design, and fabrication of a spherical inverted-F antenna (SIFA). The SIFA consists of a spherically conformal rectangular patch antenna recessed into a quarter section of a metallic ...
Analytical Techniques and Operational Perspectives for a Spherical Inverted-F Antenna
Rolando, David Lee
2012-02-14
The spherical inverted-F antenna (SIFA) is a relatively new conformal antenna design that consists of a microstrip patch resonator on a spherical ground. The SIFA resembles a planar inverted-F antenna (PIFA) that has ...
Harris, Matthew Wade
2007-09-17
This analytical model predicts the stress concentration around an elastic, spherical particle in an elastic-plastic metal matrix using strain gradient plasticity theory and a finite unit cell. The model reduces to the special case with a spherical...
Bundles with spherical Euler class Luis Guijarro Thomas Schick y Gerard Walschap z
Guijarro, Luis
Bundles with spherical Euler class Luis Guijarro #3; Thomas Schick y Gerard Walschap z Last email: thomas.schick@math.uni-muenster.de z email: gerard@math.ou.edu 1 #12; Bundles with spherical
848 Brazilian Journal of Physics, vol. 33, no. 4, December, 2003 Spherical Tokamak Development August, 2003. This paper describes the general characteristics of spherical tokamaks, or spherical tori. The paper presents also the steps in the development of the ETE (Experimento Tokamak Esf´erico) project, its
Dynamic Spherical Volumetric Simplex Splines with Applications in Biomedicine Wayne State University
Qin, Hong
Dynamic Spherical Volumetric Simplex Splines with Applications in Biomedicine Yunhao Tan , Jing Hua computational framework based on dy- namic spherical volumetric simplex splines for simulation of genus- zero to reconstruct the high-fidelity digi- tal model of a real-world object with spherical volumetric simplex splines
Static spherically symmetric solutions in mimetic gravity: rotation curves & wormholes
Myrzakulov, Ratbay; Vagnozzi, Sunny; Zerbini, Sergio
2015-01-01
In this work, we analyse static spherically symmetric solutions in the framework of mimetic gravity, an extension of general relativity where the conformal degree of freedom of gravity is isolated in a covariant fashion. Here we extend previous works by considering in addition a potential for the mimetic field. An appropriate choice of such potential allows for the reconstruction of a number of interesting cosmological and astrophysical scenarios. We explicitly show how to reconstruct such a potential for a general static spherically symmetric space-time. A number of applications and scenarios are then explored, among which traversable wormholes. Finally, we analytically reconstruct potentials which leads to solutions to the equations of motion featuring polynomial corrections to the Schwarzschild spacetime. Accurate choices for such corrections could provide an explanation for the inferred flat rotation curves of spiral galaxies within the mimetic gravity framework, without the need for particle dark matter.
Tidal dissipation in a homogeneous spherical body. I. Methods
Efroimsky, Michael; Makarov, Valeri V. E-mail: vvm@usno.navy.mil
2014-11-01
A formula for the tidal dissipation rate in a spherical body is derived from first principles to correct some mathematical inaccuracies found in the literature. The development is combined with the Darwin-Kaula formalism for tides. Our intermediate results are compared with those by Zschau and Platzman. When restricted to the special case of an incompressible spherical planet spinning synchronously without libration, our final formula can be compared with the commonly used expression from Peale and Cassen. However, the two turn out to differ, as in our expression the contributions from all Fourier modes are positive-definite, which is not the case with the formula from Peale and Cassen. Examples of the application of our expression for the tidal damping rate are provided in the work by Makarov and Efroimsky (Paper II) published back to back with the current paper.
Luciano Rezzolla; Luca Baiotti; Bruno Giacomazzo; David Link; Jose A. Font
2010-05-13
We present new results from accurate and fully general-relativistic simulations of the coalescence of unmagnetized binary neutron stars with various mass ratios. The evolution of the stars is followed through the inspiral phase, the merger and prompt collapse to a black hole, up until the appearance of a thick accretion disk, which is studied as it enters and remains in a regime of quasi-steady accretion. Although a simple ideal-fluid equation of state with \\Gamma=2 is used, this work presents a systematic study within a fully general relativistic framework of the properties of the resulting black-hole--torus system produced by the merger of unequal-mass binaries. More specifically, we show that: (1) The mass of the torus increases considerably with the mass asymmetry and equal-mass binaries do not produce significant tori if they have a total baryonic mass M_tot >~ 3.7 M_sun; (2) Tori with masses M_tor ~ 0.2 M_sun are measured for binaries with M_tot ~ 3.4 M_sun and mass ratios q ~ 0.75-0.85; (3) The mass of the torus can be estimated by the simple expression M_tor(q, M_tot) = [c_1 (1-q) + c_2](M_max-M_tot), involving the maximum mass for the binaries and coefficients constrained from the simulations, and suggesting that the tori can have masses as large as M_tor ~ 0.35 M_sun for M_tot ~ 2.8 M_sun and q ~ 0.75-0.85; (4) Using a novel technique to analyze the evolution of the tori we find no evidence for the onset of non-axisymmetric instabilities and that very little, if any, of their mass is unbound; (5) Finally, for all the binaries considered we compute the complete gravitational waveforms and the recoils imparted to the black holes, discussing the prospects of detection of these sources for a number of present and future detectors.
Naked singularities in self-similar spherical gravitational collapse
Ori, A.; Piran, T.
1987-11-09
We present general-relativistic solutions of self-similar spherical collapse of an adiabatic perfect fluid. We show that if the equation of state is soft enough (GAMMA-1<<1), a naked singularity forms. The singularity resembles the shell-focusing naked singularities that arise in dust collapse. This solution increases significantly the range of matter fields that should be ruled out in order that the cosmic-censorship hypothesis will hold.
Spherically Symmetric Solutions to Fourth-Order Theories of Gravity
T. Clifton
2006-11-10
Gravitational theories generated from Lagrangians of the form f(R) are considered. The spherically symmetric solutions to these equations are discussed, paying particular attention to features that differ from the standard Schwarzschild solution. The asymptotic form of solutions is described, as is the lack of validity of Birkhoff's theorem. Exact solutions are presented which illustrate these points and their stability and geodesics are investigated.
Relativistic electromagnetic mass models in spherically symmetric spacetime
S. K. Maurya; Y. K. Gupta; Saibal Ray; Vikram Chatterjee
2015-07-04
Under the static spherically symmetric Einstein-Maxwell spacetime of embedding class one we explore possibility of electromagnetic mass model where mass and other physical parameters have purely electromagnetic origin (Tiwari 1984, Gautreau 1985, Gron 1985). This work is in continuation of our earlier investigation (Maurya 2015a) where we developed an algorithm and found out three new solutions of electromagnetic mass models. In the present letter we consider different metric potentials $\
Self-similar spherical shock solution with sustained energy injection
V. I. Dokuchaev
2002-09-20
We present the generalization of the Sedov-Taylor self-similar strong spherical shock solution for the case of a central energy source varying in time, $E=A t^k$, where $A$ and $k$ are constants. The known Sedov-Taylor solution corresponds to a particular adiabatic case of $k=0$ or \\emph{instant shock} with an instant energy source of the shock, $E=A$. The self-similar hydrodynamic flow in the nonadiabatic $k\
Spherical Resorcinol-Formaldehyde Synthesis by Inverse Suspension Polymerization
Ray, Robert J.; Scrivens, Walter A.; Nash, Charles
2005-10-21
Base catalyzed sol-gel polycondensation of resorcinol (1,3-dihydroxybenzene) with formaldehyde by inverse suspension polymerization leads to the formation of uniform, highly cross-linked, translucent, spherical gels, which have increased selectivity and capacity for cesium ion removal from high alkaline solutions. Because of its high selectivity for cesium ion, resorcinol-formaldehyde (R-F) resins are being considered for process scale column radioactive cesium removal by ion-exchange at the Waste Treatment and Immobilization Plant (WTP), which is now under construction at the Hanford site. Other specialty resins such as Superlig{reg_sign} 644 have been ground and sieved and column tested for process scale radioactive cesium removal but show high pressure drops across the resin bed during transition from column regeneration to loading and elution. Furthermore, van Deemter considerations indicate better displacement column chromatography by the use of spherical particle beads rather than irregularly shaped ground or granular particles. In our studies batch contact equilibrium experiments using a high alkaline simulant show a definite increase in cesium loading onto spherical R-F resin. Distribution coefficient (Kd) values ranged from 777 to 429 mL/g in the presence of 0.1M and 0.7M potassium ions, respectively. Though other techniques for making R-F resins have been employed, to our knowledge no one has made spherical R-F resins by inverse suspension polymerization. Moreover, in this study we discuss the data comparisons to known algebraic isotherms used to evaluate ion-exchange resins for WTP plant scale cesium removal operations.
Dust Static Spherically Symmetric Solution in $f(R)$ Gravity
Muhammad Sharif; Hafiza Rizwana Kausar
2011-02-21
In this paper, we take dust matter and investigate static spherically symmetric solution of the field equations in metric f(R) gravity. The solution is found with constant Ricci scalar curvature and its energy distribution is evaluated by using Landau-Lifshitz energy-momentum complex. We also discuss the stability condition and constant scalar curvature condition for some specific popular choices of f(R) models in addition to their energy distribution.
TDHF fusion calculations for spherical+deformed systems
A. S. Umar; V. E. Oberacker
2006-04-04
We outline a formalism to carry out TDHF calculations of fusion cross sections for spherical + deformed nuclei. The procedure incorporates the dynamic alignment of the deformed nucleus into the calculation of the fusion cross section. The alignment results from multiple E2/E4 Coulomb excitation of the ground state rotational band. Implications for TDHF fusion calculations are discussed. TDHF calculations are done in an unrestricted three-dimensional geometry using modern Skyrme force parametrizations.
Energy partition at the collapse of spherical cavitation bubbles
Tinguely, Marc; Kobel, Philippe; Dorsaz, Nicolaz; de Bosset, Aurele; Farhat, Mohamed
2012-01-01
Spherically collapsing cavitation bubbles produce a shock wave followed by a rebound bubble. Here we present a systematic investigation of the energy partition between the rebound and the shock. Highly spherical cavitation bubbles are produced in microgravity, which suppress the buoyant pressure gradient that otherwise deteriorates the sphericity of the bubbles. We measure the radius of the rebound bubble and estimate the shock energy as a function of the initial bubble radius (2-5.6 mm) and the liquid pressure (10-80 kPa). Those measurements uncover a systematic pressure dependence of the energy partition between rebound and shock. We demonstrate that these observations agree with a physical model relying on a first-order approximation of the liquid compressibility and an adiabatic treatment of the non-condensable gas inside the bubble. Using this model we find that the energy partition between rebound and shock is dictated by a single non-dimensional parameter $\\xi = \\Delta p\\gamma^6/[{p_{g0}}^{1/\\gamma} (\\...
Method for preparing spherical ferrite beads and use thereof
Lauf, Robert J. (Oak Ridge, TN); Anderson, Kimberly K. (Knoxville, TN); Montgomery, Frederick C. (Oak Ridge, TN); Collins, Jack L. (Knoxville, TN)
2002-01-01
The invention allows the fabrication of small, dense, highly polished spherical beads of hexagonal ferrites with selected compositions for use in nonreciprocal microwave and mm-wave devices as well as in microwave absorbent or reflective coatings, composites, and the like. A porous, generally spherical bead of hydrous iron oxide is made by a sol-gel process to form a substantially rigid bead having a generally fine crystallite size and correspondingly finely distributed internal porosity. The resulting gel bead is washed and hydrothermally reacted with a soluble alkaline earth salt (typically Ba or Sr) under conditions of elevated temperature and pressure to convert the bead into a mixed hydrous iron-alkaline earth oxide while retaining the generally spherical shape. This mixed oxide bead is then washed, dried, and calcined to produce the desired (BaFe.sub.12 O.sub.19 or SrFe.sub.12 O.sub.19) crystal structure. The calcined bead is then sintered to form a dense bead of the BaFe.sub.12 O.sub.19 and SrFe.sub.12 O.sub.19 phase suitable for polishing and incorporation into various microwave devices and components.
Global oscillations of a fluid torus as a modulation mechanism for black-hole high-frequency QPOs
Michal Bursa
2005-10-15
We study strong-gravity effects on modulation of radiation emerging from accreting compact objects as a possible mechanism for flux modulation in QPOs. We construct a toy model of an oscillating torus in the slender approximation assuming thermal bremsstrahlung for the intrinsic emissivity of the medium and we compute observed (predicted) radiation signal including contribution of indirect (higher-order) images and caustics in the Schwarzschild spacetime. We show that the simplest oscillation mode in an accretion flow, axisymmetric up-and-down motion at the meridional epicyclic frequency, may be directly observable when it occurs in the inner parts of accretion flow around black holes. Together with the second oscillation mode, an in-and-out motion at the radial epicyclic frequency, it may then be responsible for the high-frequency modulations of the X-ray flux observed at two distinct frequencies (twin HF-QPOs) in micro-quasars.
) or DT fill, launching a strong converging shock that reaches 2 Gbar after rebound. The physics-ray ablation to transfer energy to a much thicker capsule rather than direct laser isochoric heating of a very
HIPPOCAMPAL SURFACE DISCRIMINATION VIA INVARIANT DESCRIPTORS OF SPHERICAL CONFORMAL MAPS
Thompson, Paul
by the National Institutes of Health through the NIH Roadmap for Medical Research, Grant U54 RR021813 entitled
Static spherically symmetric solutions for conformal gravity in three dimensions
Julio Oliva; David Tempo; Ricardo Troncoso
2009-05-10
Static spherically symmetric solutions for conformal gravity in three dimensions are found. Black holes and wormholes are included within this class. Asymptotically the black holes are spacetimes of arbitrary constant curvature, and they are conformally related to the matching of different solutions of constant curvature by means of an improper conformal transformation. The wormholes can be constructed from suitable identifications of a static universe of negative spatial curvature, and it is shown that they correspond to the conformal matching of two black hole solutions with the same mass.
Full light absorption in single arrays of spherical nanoparticles
Ra'di, Y; Kosulnikov, S U; Omelyanovich, M M; Morits, D; Osipov, A V; Simovski, C R; Tretyakov, S A
2015-01-01
In this paper we show that arrays of core-shell nanoparticles function as effective thin absorbers of light. In contrast to known metamaterial absorbers, the introduced absorbers are formed by single planar arrays of spherical inclusions and enable full absorption of light incident on either or both sides of the array. We demonstrate possibilities for realizing different kinds of symmetric absorbers, including resonant, ultra-broadband, angularly selective, and all-angle absorbers. The physical principle behind these designs is explained considering balanced electric and magnetic responses of unit cells. Photovoltaic devices and thermal emitters are the two most important potential applications of the proposed designs.
Spherically symmetric electromagnetic mass models of embedding class one
S. K. Maurya; Y. K. Gupta; Saibal Ray; Sourav Roy Chowdhury
2015-05-30
In this article we consider the static spherically symmetric spacetime metric of embedding class one. Specifically three new electromagnetic mass models are derived where the solutions are entirely dependent on the electromagnetic field, such that the physical parameters, like density, pressure etc. do vanish for the vanishing charge. We have analyzed schematically all these three sets of solutions related to electromagnetic mass models by plotting graphs and shown that they can pass through all the physical tests performed by us. To validate these special type of solutions related to electromagnetic mass models a comparison has been done with that of compact stars and shown exclusively the feasibility of the models.
Angular Momentum Mixing in a Non-spherical Color Superconductor
Bo Feng; Defu Hou; Hai-cang Ren
2007-11-28
We study the angular momentum mixing effects in the color superconductor with non-spherical pairing. We first clarify the concept of the angular momentum mixing with a toy model for non-relativistic and spinless fermions. Then we derive the gap equation for the polar phase of dense QCD by minimizing the CJT free energy. The solution of the gap equation consists of all angular momentum partial waves of odd parity. The corresponding free energy is found to be lower than that reported in the literature with p-wave only.
Asymptotics of spherical superfunctions on rank one Riemannian symmetric superspaces
Alexander Alldridge; Wolfgang Palzer
2014-11-21
We compute the Harish-Chandra $c$-function for a generic class of rank-one purely non-compact Riemannian symmetric superspaces $X=G/K$ in terms of Euler $\\Gamma$ functions, proving that it is meromorphic. Compared to the even case, the poles of the $c$-function are shifted into the right half-space. We derive the full asymptotic Harish-Chandra series expansion of the spherical superfunctions on $X$. In the case where the multiplicity of the simple root is an even negative number, they have a closed expression as Jacobi polynomials for an unusual choice of parameters.
Spherical Accretion onto Neutron Stars Revisited: Are Hot Solutions Possible ?
Roberto Turolla; Luca Zampieri; Monica Colpi; Aldo Treves
1994-02-21
Stationary, spherical accretion onto an unmagnetized neutron star is here reconsidered on the wake of the seminal paper by Zel'dovich \\& Shakura (1969). It is found that new ``hot'' solutions may exist for a wide range of luminosities. These solutions are characterized by a high temperature, $10^{9}\\div 10^{11}$ K, and arise from a stationary equilibrium model where the dominant radiative mechanisms are multiple Compton scattering and bremsstrahlung emission. For low luminosities, $\\mincir 10^{-2} \\ L_{E}$, only the ``cold'' (\\`a la Zel'dovich and Shakura) solution is present.
Minimal Length Effects on Tunnelling from Spherically Symmetric Black Holes
Benrong Mu; Peng Wang; Haitang Yang
2015-01-24
In this paper, we investigate effects of the minimal length on quantum tunnelling from spherically symmetric black holes using the Hamilton-Jacobi method incorporating the minimal length. We first derive the deformed Hamilton-Jacobi equations for scalars and fermions, both of which have the same expressions. The minimal length correction to the Hawking temperature is found to depend on the black hole's mass and the mass and angular momentum of emitted particles. Finally, we calculate a Schwarzschild black hole's luminosity and find the black hole evaporates to zero mass in infinite time.
Minimal Length Effects on Tunnelling from Spherically Symmetric Black Holes
Mu, Benrong; Yang, Haitang
2015-01-01
In this paper, we investigate effects of the minimal length on quantum tunnelling from spherically symmetric black holes using the Hamilton-Jacobi method incorporating the minimal length. We first derive the deformed Hamilton-Jacobi equations for scalars and fermions, both of which have the same expressions. The minimal length correction to the Hawking temperature is found to depend on the black hole's mass and the mass and angular momentum of emitted particles. Finally, we calculate a Schwarzschild black hole's luminosity and find the black hole evaporates to zero mass in infinite time.
Geometrodynamics in a spherically symmetric, static crossflow of null dust
Zsolt Horváth; Zoltán Kovács; László Á. Gergely
2006-10-12
The spherically symmetric, static spacetime generated by a crossflow of non-interacting radiation streams, treated in the geometrical optics limit (null dust) is equivalent to an anisotropic fluid forming a radiation atmosphere of a star. This reference fluid provides a preferred / internal time, which is employed as a canonical coordinate. Among the advantages we encounter a new Hamiltonian constraint, which becomes linear in the momentum conjugate to the internal time (therefore yielding a functional Schr\\"{o}dinger equation after quantization), and a strongly commuting algebra of the new constraints.
Geometrodynamics in a spherically symmetric, static crossflow of null dust
Horváth, Z; Kovács, Z; Horv\\'{a}th, Zsolt; Kov\\'{a}cs, Zolt\\'{a}n
2006-01-01
The spherically symmetric, static spacetime generated by a crossflow of non-interacting radiation streams, treated in the geometrical optics limit (null dust) is equivalent to an anisotropic fluid forming a stellar atmosphere. This reference fluid provides a preferred / internal time, which is employed as a canonical coordinate. Among the advantages we encounter a new Hamiltonian constraint, which becomes linear in the momentum conjugate to the internal time (therefore yielding a functional Schr\\"{o}dinger equation after quantization), and a strongly commuting algebra of the new constraints.
A non-conforming 3D spherical harmonic transport solver
Van Criekingen, S.
2006-07-01
A new 3D transport solver for the time-independent Boltzmann transport equation has been developed. This solver is based on the second-order even-parity form of the transport equation. The angular discretization is performed through the expansion of the angular neutron flux in spherical harmonics (PN method). The novelty of this solver is the use of non-conforming finite elements for the spatial discretization. Such elements lead to a discontinuous flux approximation. This interface continuity requirement relaxation property is shared with mixed-dual formulations such as the ones based on Raviart-Thomas finite elements. Encouraging numerical results are presented. (authors)
Spherical Wave Propagation in a Nonlinear Elastic Medium
Korneev, Valeri A.
2009-07-01
Nonlinear propagation of spherical waves generated by a point-pressure source is considered for the cases of monochromatic and impulse primary waveforms. The nonlinear five-constant elastic theory advanced by Murnaghan is used where general equations of motion are put in the form of vector operators, which are independent of the coordinate system choice. The ratio of the nonlinear field component to the primary wave in the far field is proportional to ln(r) where r is a propagation distance. Near-field components of the primary field do not contribute to the far field of nonlinear component.
Spherical geodesic mesh generation (Conference) | SciTech Connect
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Electrostatic spherically symmetric configurations in gravitating nonlinear electrodynamics
Diaz-Alonso, J.; Rubiera-Garcia, D. [LUTH, Observatoire de Paris, CNRS, , USAUniversite Paris Diderot, 5 Place Jules Janssen, 92190 Meudon (France) and Departamento de Fisica, Universidad de Oviedo, Avda. Calvo Sotelo 18, E-33007 Oviedo, Asturias (Spain)
2010-03-15
We perform a study of the gravitating electrostatic spherically symmetric (G-ESS) solutions of Einstein field equations minimally coupled to generalized nonlinear Abelian gauge models in three space dimensions. These models are defined by Lagrangian densities which are general functions of the gauge field invariants, restricted by some physical conditions of admissibility. They include the class of nonlinear electrodynamics supporting electrostatic spherically symmetric (ESS) nontopological soliton solutions in absence of gravity. We establish that the qualitative structure of the G-ESS solutions of admissible models is fully characterized by the asymptotic and central-field behaviors of their ESS solutions in flat space (or, equivalently, by the behavior of the Lagrangian densities in vacuum and on the point of the boundary of their domain of definition, where the second gauge invariant vanishes). The structure of these G-ESS configurations for admissible models supporting divergent-energy ESS solutions in flat space is qualitatively the same as in the Reissner-Nordstroem case. In contrast, the G-ESS configurations of the models supporting finite-energy ESS solutions in flat space exhibit new qualitative features, which are discussed in terms of the Arnowitt-Deser-Misner mass, the charge, and the soliton energy. Most of the results concerning well-known models, such as the electrodynamics of Maxwell, Born-Infeld, and the Euler-Heisenberg effective Lagrangian of QED, minimally coupled to gravitation, are shown to be corollaries of general statements of this analysis.
Horizons versus singularities in spherically symmetric space-times
Bronnikov, K. A.; Elizalde, E.; Odintsov, S. D.; Zaslavskii, O. B.
2008-09-15
We discuss different kinds of Killing horizons possible in static, spherically symmetric configurations and recently classified as 'usual', 'naked', and 'truly naked' ones depending on the near-horizon behavior of transverse tidal forces acting on an extended body. We obtain the necessary conditions for the metric to be extensible beyond a horizon in terms of an arbitrary radial coordinate and show that all truly naked horizons, as well as many of those previously characterized as naked and even usual ones, do not admit an extension and therefore must be considered as singularities. Some examples are given, showing which kinds of matter are able to create specific space-times with different kinds of horizons, including truly naked ones. Among them are fluids with negative pressure and scalar fields with a particular behavior of the potential. We also discuss horizons and singularities in Kantowski-Sachs spherically symmetric cosmologies and present horizon regularity conditions in terms of an arbitrary time coordinate and proper (synchronous) time. It turns out that horizons of orders 2 and higher occur in infinite proper times in the past or future, but one-way communication with regions beyond such horizons is still possible.
New second derivative theories of gravity for spherically symmetric spacetimes
Rakesh Tibrewala
2015-03-17
We present new second derivative, generally covariant theories of gravity for spherically symmetric spacetimes (general covariance is in the $t-r$ plane) belonging to the class where the spherically symmetric Einstein-Hilbert theory is modified by the presence of $g_{\\theta\\theta}$ dependent functions. In $3+1$ dimensional vacuum spacetimes there is three-fold infinity of freedom in constructing such theories as revealed by the presence of three arbitrary $g_{\\theta\\theta}$ dependent functions in the Hamiltonian (matter Hamiltonian also has the corresponding freedom). This result is not a contradiction to the theorem of Hojman et. al. [1] which is applicable to the full theory whereas the above conclusion is for symmetry reduced sector of the theory (which has a much reduced phase space). In the full theory where there are no special symmetries, the result of Hojman et. al. will continue to hold. In the process we also show that theories where the constraint algebra is deformed by the presence of $g_{\\theta\\theta}$ dependent functions - as is the case in the presence of inverse triad corrections in loop quantum gravity - can always be brought to the form where they obey the standard (undeformed) constraint algebra by performing a suitable canonical transformation. We prove that theories obtained after performing canonical transformation are inequivalent to the symmetry reduced general relativity and that the resulting theories fall within the purview of the theories mentioned above.
Numerical Relativity in Spherical Polar Coordinates: Off-center Simulations
Thomas W. Baumgarte; Pedro J. Montero; Ewald Müller
2015-06-03
We have recently presented a new approach for numerical relativity simulations in spherical polar coordinates, both for vacuum and for relativistic hydrodynamics. Our approach is based on a reference-metric formulation of the BSSN equations, a factoring of all tensor components, as well as a partially implicit Runge-Kutta method, and does not rely on a regularization of the equations, nor does it make any assumptions about the symmetry across the origin. In order to demonstrate this feature we present here several off-centered simulations, including simulations of single black holes and neutron stars whose center is placed away from the origin of the coordinate system, as well as the asymmetric head-on collision of two black holes. We also revisit our implementation of relativistic hydrodynamics and demonstrate that a reference-metric formulation of hydrodynamics together with a factoring of all tensor components avoids problems related to the coordinate singularities at the origin and on the axes. As a particularly demanding test we present results for a shock wave propagating through the origin of the spherical polar coordinate system.
Leighly, Karen M; Grupe, Dirk; Terndrup, Donald M; Komossa, S
2015-01-01
We report the discovery of an occultation event in the low-luminosity narrow-line Seyfert 1 galaxy WPVS 007 in 2015 February and March. In concert with longer timescale variability, these observations place strong constraints on the nature and location of the absorbing material. Swift monitoring has revealed a secular decrease since ~2010 accompanied by flattening of the optical and UV photometry that suggests variable reddening. Analysis of four Hubble Space Telescope COS observations since 2010, including a Director's Discretionary time observation during the occultation, shows that the broad-absorption-line velocity offset and the CIV emission-line width both decrease as the reddening increases. The occultation dynamical timescale, the BAL variability dynamical timescale, and the density of the BAL gas show that both the reddening material and the broad-absorption-line gas are consistent with an origin in the torus. These observations can be explained by a scenario in which the torus is clumpy with variabl...
Dynamic fracture of inorganic glasses by hard spherical and conical projectiles
Chaudhri, M. Munawar
2015-02-23
stream_source_info Chaudhri_Dynamic fracture of inorganic glasses by hard spherical and conical projectiles_2015_Philisophical Transactions A..pdf.txt stream_content_type text/plain stream_size 81626 Content-Encoding UTF-8 stream... _name Chaudhri_Dynamic fracture of inorganic glasses by hard spherical and conical projectiles_2015_Philisophical Transactions A..pdf.txt Content-Type text/plain; charset=UTF-8 1 Dynamic fracture of inorganic glasses by hard spherical and conical...
Electrostatic self-energy in static black holes with spherical symmetry
B. Linet
2000-06-28
We determine the expression of the electrostatic self-energy for a point charge in the static black holes with spherical symmetry having suitable properties
Cauchy-perturbative matching reexamined: Tests in spherical symmetry
Zink, Burkhard [Max-Planck-Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching (Germany); Pazos, Enrique [Department of Physics and Astronomy, 202 Nicholson Hall, Louisana State University, Baton Rouge, Louisiana 70803 (United States); Center for Computation and Technology, 302 Johnston Hall, Louisana State University, Baton Rouge, Louisiana 70803 (United States); Departamento de Matematica, Universidad de San Carlos de Guatemala, Edificio T4, Facultad de Ingenieria, Ciudad Universitaria Z. 12 (Guatemala); Diener, Peter; Tiglio, Manuel [Department of Physics and Astronomy, 202 Nicholson Hall, Louisana State University, Baton Rouge, Louisiana 70803 (United States); Center for Computation and Technology, 302 Johnston Hall, Louisana State University, Baton Rouge, Louisiana 70803 (United States)
2006-04-15
During the last few years progress has been made on several fronts making it possible to revisit Cauchy-perturbative matching (CPM) in numerical relativity in a more robust and accurate way. This paper is the first in a series where we plan to analyze CPM in the light of these new results. One of the new developments is an understanding of how to impose constraint-preserving boundary conditions (CPBC); though most of the related research has been driven by outer boundaries, one can use them for matching interface boundaries as well. Another front is related to numerically stable evolutions using multiple patches, which in the context of CPM allows the matching to be performed on a spherical surface, thus avoiding interpolations between Cartesian and spherical grids. One way of achieving stability for such schemes of arbitrary high order is through the use of penalty techniques and discrete derivatives satisfying summation by parts (SBP). Recently, new, very efficient and high-order accurate derivatives satisfying SBP and associated dissipation operators have been constructed. Here we start by testing all these techniques applied to CPM in a setting that is simple enough to study all the ingredients in great detail: Einstein's equations in spherical symmetry, describing a black hole coupled to a massless scalar field. We show that with the techniques described above, the errors introduced by Cauchy-perturbative matching are very small, and that very long-term and accurate CPM evolutions can be achieved. Our tests include the accretion and ring-down phase of a Schwarzschild black hole with CPM, where we find that the discrete evolution introduces, with a low spatial resolution of {delta}r=M/10, an error of 0.3% after an evolution time of 1,000,000M. For a black hole of solar mass, this corresponds to approximately 5s, and is therefore at the lower end of timescales discussed e.g. in the collapsar model of gamma-ray burst engines.
Hartman, C W; Reisman, D B; McLean, H S; Thomas, J
2007-05-30
A fusion reactor is described in which a moving string of mutually repelling compact toruses (alternating helicity, unidirectional Btheta) is generated by repetitive injection using a magnetized coaxial gun driven by continuous gun current with alternating poloidal field. An injected CT relaxes to a minimum magnetic energy equilibrium, moves into a compression cone, and enters a conducting cylinder where the plasma is heated to fusion-producing temperature. The CT then passes into a blanketed region where fusion energy is produced and, on emergence from the fusion region, the CT undergoes controlled expansion in an exit cone where an alternating poloidal field opens the flux surfaces to directly recover the CT magnetic energy as current which is returned to the formation gun. The CT String Reactor (CTSTR) reactor satisfies all the necessary MHD stability requirements and is based on extrapolation of experimentally achieved formation, stability, and plasma confinement. It is supported by extensive 2D, MHD calculations. CTSTR employs minimal external fields supplied by normal conductors, and can produce high fusion power density with uniform wall loading. The geometric simplicity of CTSTR acts to minimize initial and maintenance costs, including periodic replacement of the reactor first wall.
Giacomelli, L.; Department of Physics, Università degli Studi di Milano-Bicocca, Milano ; Conroy, S.; Department of Physics and Astronomy, Uppsala University, Uppsala ; Gorini, G.; Horton, L.; Murari, A.; Popovichev, S.; Syme, D. B.
2014-02-15
The Joint European Torus (JET, Culham, UK) is the largest tokamak in the world devoted to nuclear fusion experiments of magnetic confined Deuterium (D)/Deuterium-Tritium (DT) plasmas. Neutrons produced in these plasmas are measured using various types of neutron detectors and spectrometers. Two of these instruments on JET make use of organic liquid scintillator detectors. The neutron emission profile monitor implements 19 liquid scintillation counters to detect the 2.45 MeV neutron emission from D plasmas. A new compact neutron spectrometer is operational at JET since 2010 to measure the neutron energy spectra from both D and DT plasmas. Liquid scintillation detectors are sensitive to both neutron and gamma radiation but give light responses of different decay time such that pulse shape discrimination techniques can be applied to identify the neutron contribution of interest from the data. The most common technique consists of integrating the radiation pulse shapes within different ranges of their rising and/or trailing edges. In this article, a step forward in this type of analysis is presented. The method applies a tomographic analysis of the 3-dimensional neutron and gamma pulse shape and pulse height distribution data obtained from liquid scintillation detectors such that n/? discrimination can be improved to lower energies and additional information can be gained on neutron contributions to the gamma events and vice versa.
Webster, A. J. Webster, S. J.
2014-11-15
During July 2012, 150 almost identical H-mode plasmas were consecutively created in the Joint European Torus, providing a combined total of approximately 8 minutes of steady-state plasma with 15?000 Edge Localised Modes (ELMs). In principle, each of those 15?000 ELMs are statistically equivalent. Here, the changes in edge density and plasma energy associated with those ELMs are explored, using the spikes in Beryllium II (527?nm) radiation as an indicator for the onset of an ELM. Clearly different timescales are observed during the ELM process. Edge temperature falls over a 2?ms timescale, edge density and pressure fall over a 5?ms timescale, and there is an additional 10?ms timescale that is consistent with a resistive relaxation of the plasma's edge. The statistical properties of the energy and density losses due to the ELMs are explored. For these plasmas the ELM energy (?E) is found to be approximately independent of the time between ELMs, despite the average ELM energy (??E?) and average ELM frequency (f) being consistent with the scaling of ??E??1/f. Instead, beyond the first 0.02 s of waiting time between ELMs, the energy losses due to individual ELMs are found to be statistically the same. Surprisingly no correlation is found between the energies of consecutive ELMs either. A weak link is found between the density drop and the ELM waiting time. Consequences of these results for ELM control and modelling are discussed.
Frequency Dependent Specific Heat from Thermal Effusion in Spherical Geometry
Bo Jakobsen; Niels Boye Olsen; Tage Christensen
2010-03-11
We present a novel method of measuring the frequency dependent specific heat at the glass transition applied to 5-polyphenyl-4-ether. The method employs thermal waves effusing radially out from the surface of a spherical thermistor that acts as both a heat generator and thermometer. It is a merit of the method compared to planar effusion methods that the influence of the mechanical boundary conditions are analytically known. This implies that it is the longitudinal rather than the isobaric specific heat that is measured. As another merit the thermal conductivity and specific heat can be found independently. The method has highest sensitivity at a frequency where the thermal diffusion length is comparable to the radius of the heat generator. This limits in practise the frequency range to 2-3 decades. An account of the 3omega-technique used including higher order terms in the temperature dependency of the thermistor and in the power generated is furthermore given.
Micro-tearing modes in spherical and conventional tokamaks
Moradi, S; Guttenfelder, W; Fülöp, T; Mollén, A
2013-01-01
The onset and characteristics of Micro-Tearing Modes (MTM) in the core of spherical (NSTX) and conventional tokamaks (ASDEX-UG and JET) are studied through local linear gyrokinetic simulations with gyro [J. Candy and E. Belli, General Atomics Report GA-A26818 (2011)]. For experimentally relevant core plasma parameters in the NSTX and ASDEX-UG tokamaks, in agreement with previous works, we find MTMs as the dominant linear instability. Also, for JET-like core parameters considered in our study an MTM is found as the most unstable mode. In all these plasmas, finite collisionality is needed for MTMs to become unstable and the electron temperature gradient is found to be the fundamental drive. However, a significant difference is observed in the dependence of linear growth rate of MTMs on electron temperature gradient. While it varies weakly and non-monotonically in JET and ASDEX-UG plasmas, in NSTX it increases with the electron temperature gradient.
Distorted black holes from a vacuum 5-d spherical solution
Capistrano, Abraão J S; Ulhoa, Sergio C; Amorim, Ronni G G
2015-01-01
We study the deformation caused by the influence of extrinsic curvature on a vacuum spherically symmetric metric embedded in a 5-d bulk. In this sense, we investigate the produced stationary black-holes and derive general properties such as its mass and horizons. As an application, a test moving particle near such black-holes is also shown as well the distortion caused by extrinsic curvature on its movement. Accordingly, using asymptotically conformal flat condition on the extrinsic curvature and an analytical expansion of a set of \\emph{n}-scalar fields, we show that the resulting black holes must be large and constrained in the range $-1/2 \\leq n \\leq 1.8$ that are locally thermodynamically stable, but not globally preferred.
Multichannel matched filtering for spherical gravitational wave antennas
Costa, Carlos Filipe Da Silva; Sturani, Riccardo
2009-01-01
We study the performance of a multidimensional matched filter as a follow-up module of the coherent method recently developed by two of us for the detection of gravitational wave bursts by spherical resonant detectors. We have tested this strategy on the same set of injections used for the coherent method and found that the matched filter sensibly improves the determination of relevant parameters as the arrival time, amplitude, central frequency and arrival direction of the signal. The matched filter also improves the false alarm rate, reducing it roughly by a factor of 3. The hierarchical structure of the whole analysis pipeline allows to obtain these results without a significant increase of the computation time.
Brane solutions of a spherical sigma model in six dimensions
Hyun Min Lee; Antonios Papazoglou
2004-11-16
We explore solutions of six dimensional gravity coupled to a non-linear sigma model, in the presence of co-dimension two branes. We investigate the compactifications induced by a spherical scalar manifold and analyze the conditions under which they are of finite volume and singularity free. We discuss the issue of single-valuedness of the scalar fields and provide some special embedding of the scalar manifold to the internal space which solves this problem. These brane solutions furnish some self-tuning features, however they do not provide a satisfactory explanation of the vanishing of the effective four dimensional cosmological constant. We discuss the properties of this model in relation with the self-tuning example based on a hyperbolic sigma model.
Plasma Viscosity with Mass Transport in Spherical ICF Implosion Simulations
Vold, Erik L; Ortega, Mario I; Moll, Ryan; Fenn, Daniel; Molvig, Kim
2015-01-01
The effects of viscosity and small-scale atomic-level mixing on plasmas in inertial confinement fusion (ICF) currently represent challenges in ICF research. Many current ICF hydrodynamic codes ignore the effects of viscosity though recent research indicates viscosity and mixing by classical transport processes may have a substantial impact on implosion dynamics. We have implemented a Lagrange hydrodynamic code in one-dimensional spherical geometry with plasma viscosity and mass transport and including a three temperature model for ions, electrons, and radiation treated in a gray radiation diffusion approximation. The code is used to study ICF implosion differences with and without plasma viscosity and to determine the impacts of viscosity on temperature histories and neutron yield. It was found that plasma viscosity has substantial impacts on ICF shock dynamics characterized by shock burn timing, maximum burn temperatures, convergence ratio, and time history of neutron production rates. Plasma viscosity reduc...
Spherically Symmetric N-body Simulations with General Relativistic Dynamics
Adamek, Julian; Hotchkiss, Shaun
2015-01-01
Within a cosmological context, we study the behaviour of collisionless particles in the weak field approximation to General Relativity, allowing for large gradients of the fields and relativistic velocities for the particles. We consider a spherically symmetric setup such that high resolution simulations are possible with minimal computational resources. We test our formalism by comparing it to two exact solutions: the Schwarzschild solution and the Lema\\^itre-Tolman-Bondi model. In order to make the comparison we consider redshifts and lensing angles of photons passing through the simulation. These are both observable quantities and hence are gauge independent. We demonstrate that our scheme is more accurate than a Newtonian scheme, correctly reproducing the leading-order post-Newtonian correction. In addition, our setup is able to handle shell-crossings, which is not possible within a fluid model. Furthermore, by introducing angular momentum, we find configurations corresponding to bound objects which may p...
A simple procedure to prepare spherical {alpha}-alumina powders
Liu Hongyu [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012 (China); Ning Guiling [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012 (China)], E-mail: ninggl@dlut.edu.cn; Gan Zhihong; Lin Yuan [State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012 (China)
2009-04-02
Spherical {alpha}-alumina powders were prepared by the controlled hydrolysis of aluminum isopropoxide in a hydrolysis system consisting of octanol and acetonitrile. Diverse solvents to dissolve reactant formed diverse hydrolysis systems and affected particle shape of {alpha}-alumina powders. The precursors crystallized to {gamma}-alumina at 1000 deg. C and converted to {alpha}-alumina at 1150 deg. C without intermediate phases. The particle morphology of precursor was retained after it crystallized to {alpha}-alumina. The heating rate influenced the particle shape and the state of agglomeration during calcination process. The thermal properties of the precursors were characterized by thermal gravimetric and differential thermal analysis. X-ray diffraction technique was used to confirm the conversion of crystalline phase of alumina powders from amorphous to {alpha}-phase. Transmission electron microscopy was used to investigate the morphologies and size of the precursors and products.
Reactive self-heating model of aluminum spherical nanoparticles
Karen S. Martirosyan; Maxim Zyskin
2012-12-17
Aluminum-oxygen reaction is important in many highly energetic, high pressure generating systems. Recent experiments with nanostructured thermites suggest that oxidation of aluminum nanoparticles occurs in a few microseconds. Such rapid reaction cannot be explained by a conventional diffusion-based mechanism. We present a rapid oxidation model of a spherical aluminum nanoparticle, using Cabrera-Mott moving boundary mechanism, and taking self-heating into account. In our model, electric potential solves the nonlinear Poisson equation. In contrast with the Coulomb potential, a "double-layer" type solution for the potential and self-heating leads to enhanced oxidation rates. At maximal reaction temperature of 2000 C, our model predicts overall oxidation time scale in microseconds range, in agreement with experimental evidence.
Reactive self-heating model of aluminum spherical nanoparticles
Martirosyan, Karen S
2012-01-01
Aluminum-oxygen reaction is important in many highly energetic, high pressure generating systems. Recent experiments with nanostructured thermites suggest that oxidation of aluminum nanoparticles occurs in a few microseconds. Such rapid reaction cannot be explained by a conventional diffusion-based mechanism. We present a rapid oxidation model of a spherical aluminum nanoparticle, using Cabrera-Mott moving boundary mechanism, and taking self-heating into account. In our model, electric potential solves the nonlinear Poisson equation. In contrast with the Coulomb potential, a "double-layer" type solution for the potential and self-heating leads to enhanced oxidation rates. At maximal reaction temperature of 2000 C, our model predicts overall oxidation time scale in microseconds range, in agreement with experimental evidence.
Spherically symmetric cosmological spacetimes with dust and radiation — numerical implementation
Lim, Woei Chet [Department of Mathematics, University of Waikato, Private Bag 3105, Hamilton 3240 (New Zealand); Regis, Marco [Dipartimento di Fisica, Università di Torino and INFN, Torino (Italy); Clarkson, Chris, E-mail: wclim@waikato.ac.nz, E-mail: regis@to.infn.it, E-mail: chris.clarkson@gmail.com [Astrophysics, Cosmology and Gravity Centre, and Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701, Cape Town (South Africa)
2013-10-01
We present new numerical cosmological solutions of the Einstein Field Equations. The spacetime is spherically symmetric with a source of dust and radiation approximated as a perfect fluid. The dust and radiation are necessarily non-comoving due to the inhomogeneity of the spacetime. Such a model can be used to investigate non-linear general relativistic effects present during decoupling or big-bang nucleosynthesis, as well as for investigating void models of dark energy with isocurvature degrees of freedom. We describe the full evolution of the spacetime as well as the redshift and luminosity distance for a central observer. After demonstrating accuracy of the code, we consider a few example models, and demonstrate the sensitivity of the late time model to the degree of inhomogeneity of the initial radiation contrast.
Skyrme RPA for spherical and axially symmetric nuclei
Repko, Anton; Nesterenko, V O; Reinhard, P -G
2015-01-01
Random Phase Approximation (RPA) is the basic method for calculation of excited states of nuclei over the Hartree-Fock ground state, suitable also for energy density functionals (EDF or DFT). We developed a convenient formalism for expressing densities and currents in a form of reduced matrix elements, which allows fast calculation of spectra for spherical nuclei. All terms of Skyrme functional were taken into account, so it is possible to calculate electric, magnetic and vortical/toroidal/compression transitions and strength functions of any multipolarity. Time-odd (spin) terms in Skyrme functional become important for magnetic M1 and isovector toroidal E1 transitions. It was also found that transition currents in pygmy region (low-lying part of E1 resonance) exhibit isoscalar toroidal flow, so the previously assumed picture of neutron-skin vibration is not the only mechanism present in pygmy transitions. RPA calculations with heavy axially-symmetric nuclei now become feasible on ordinary PC. Detailed formul...
Dirac-Kähler particle in Riemann spherical space: boson interpretation
A. M. Ishkhanyan; O. Florea; E. M. Ovsiyuk; V. M. Red'kov
2014-11-23
In the context of the composite boson interpretation, we construct the exact general solution of the Dirac--K\\"ahler equation for the case of the spherical Riemann space of constant positive curvature, for which due to the geometry itself one may expect to have a discrete energy spectrum. In the case of the minimal value of the total angular momentum, $j=0$, the radial equations are reduced to second-order ordinary differential equations, which are straightforwardly solved in terms of the hypergeometric functions. For non-zero values of the total angular momentum, however, the radial equations are reduced to a pair of complicated fourth-order differential equations. Employing the factorization approach, we derive the general solution of these equations involving four independent fundamental solutions written in terms of combinations of the hypergeometric functions. The corresponding discrete energy spectrum is then determined via termination of the involved hypergeometric series, resulting in quasi-polynomial wave-functions. The constructed solutions lead to notable observations when compared with those for the ordinary Dirac particle. The energy spectrum for the Dirac-K\\"ahler particle in spherical space is much more complicated. Its structure substantially differs from that for the Dirac particle since it consists of two paralleled energy level series each of which is twofold degenerate. Besides, none of the two separate series coincides with the series for the Dirac particle. Thus, the Dirac--K\\"ahler field cannot be interpreted as a system of four Dirac fermions. Additional arguments supporting this conclusion are discussed.
On spherically-symmetric accretion by a collisionless polytrope
B. M. Lewis
2001-04-02
An isolated, spherically-symmetric, self-gravitating, collisionless system is always a polytrope when it reaches equilibrium (Nakamura 2000). This strongly suggests as a corollary, however, that the same polytrope dominates its precursor states, since the dynamical equations for its constituents can be time-reversed. Moreover this assumption, which precludes a polytrope from ever accreting 100% of the mass from an infalling shell, as a subsequent state will eventually be a polytrope, is confirmed now by our finding that a collisionless polytrope cannot accrete 100% of an infalling shell while simultaneously guaranteeing that the entropy of the Universe as a whole increases. These strictures are only evaded by the shedding of some mass. A polytrope must lose mass to gain mass. We deduce from the time-reversible property of a collisionless polytrope that the scalar sum, P, over constituent momenta in its rest frame is an independent state variable that is conserved with respect to its surface radius through interactions between a polytrope and an infalling shell. This new constraint, together with conservation of energy, enables us (i) to show that an isolated polytrope is indeed stable against spherically-symmetric mass-loss, which is the essential content of our initial assumption; (ii) to calculate both the velocity and the fraction of infall-mass returned to infinity, provided the "accretion law" between the change in mass and surface radius is specified. Numerical results confirm a frequent empirical finding (Livio 2000) that the velocity of a mass outflow is of the same order of magnitude as the escape velocity from the system.
Fire Safety Tests for Spherical Resorcinol Formaldehyde Resin: Data Summary Report
Kim, Dong-Sang; Peterson, Reid A.; Schweiger, Michael J.
2012-07-30
A draft safety evaluation of the scenario for spherical resorcinol-formaldehyde (SRF) resin fire inside the ion exchange column was performed by the Hanford Tank Waste Treatment and Immobilization Plant (WTP) Fire Safety organization. The result of this draft evaluation suggested a potential change of the fire safety classification for the Cesium Ion Exchange Process System (CXP) emergency elution vessels, equipment, and piping, which may be overly bounding based on the fire performance data from the manufacturer of the ion exchange resin selected for use at the WTP. To resolve this question, the fire properties of the SRF resin were measured by Southwest Research Institute (SwRI), following the American Society for Testing and Materials (ASTM) standard procedures, through a subcontract managed by Pacific Northwest National Laboratory (PNNL). For some tests, the ASTM standard procedures were not entirely appropriate or practical for the SRF resin material, so the procedures were modified and deviations from the ASTM standard procedures were noted. This report summarizes the results of fire safety tests performed and reported by SwRI. The efforts by PNNL were limited to summarizing the test results provided by SwRI into one consolidated data report. All as-received SwRI reports are attached to this report in the Appendix. Where applicable, the precision and bias of each test method, as given by each ASTM standard procedure, are included and compared with the SwRI test results of the SRF resin.
Fire Safety Tests for Cesium-Loaded Spherical Resorcinol Formaldehyde Resin: Data Summary Report
Kim, Dong-Sang; Schweiger, Michael J.; Peterson, Reid A.
2012-09-01
A draft safety evaluation of the scenario for spherical resorcinol formaldehyde (SRF) resin fire inside the ion exchange column was performed by the Hanford Tank Waste Treatment and Immobilization Plant (WTP) Fire Safety organization. The result of this draft evaluation suggested a potential change of the fire safety classification for the Cesium Ion Exchange Process System (CXP) emergency elution vessels, equipment, and piping. To resolve this question, the fire properties of the SRF resin were measured by Southwest Research Institute (SwRI) through a subcontract managed by Pacific Northwest National Laboratory (PNNL). The results of initial fire safety tests on the SRF resin were documented in a previous report (WTP-RPT-218). The present report summarizes the results of additional tests performed by SwRI on the cesium-loaded SRF resin. The efforts by PNNL were limited to summarizing the test results provided by SwRI into one consolidated data report. The as-received SwRI report is attached to this report in the Appendix A. Where applicable, the precision and bias of each test method, as given by each American Society for Testing and Materials (ASTM) standard procedure, are included and compared with the SwRI test results of the cesium-loaded SRF resin.
On the Computation of the Direct Kinematics of Parallel Spherical Mechanisms Using
On the Computation of the Direct Kinematics of Parallel Spherical Mechanisms Using Bernstein Solving the direct kinematics of parallel spherical mechanisms with l legs boils down to solving systems the direct kinematics of these mechanisms that takes ad- vantage of the subdivision and convex hull
An exact solution for the Casimir force in a spherically symmetric medium
Ulf Leonhardt; William M. R. Simpson
2011-07-03
We calculated the force of the quantum vacuum, the Casimir force, in a spherically symmetric medium, Maxwell's fish eye, surrounded by a perfect mirror and derived an exact analytic solution. Our solution questions the idea that the Casimir force of a spherical mirror is repulsive - we found an attractive force that diverges at the mirror.
The Dual Horospherical Radon Transform as a Limit of Spherical Radon Transforms
Pasquale, Angela
The Dual Horospherical Radon Transform as a Limit of Spherical Radon Transforms J. Hilgert, A of G. The horospherical Radon transform maps functions on X to functions on HorX by integrating over the dual horospherical Radon transform as a limit of dual spherical Radon transforms. 1. Introduction
Diffusion within a Layered, Graphite-Like, Spherical Electrode Theoretical Aspects
Taylor, Philip L.
Diffusion within a Layered, Graphite-Like, Spherical Electrode Theoretical Aspects Paul B. Antohi. Within this model, which mimics a layered, graphite-like spherical electrode, species can enter or leave further performance optimization of Li+ batteries have generated renewed interest into experimental
The dynamic response of edge clamped plates loaded by spherically expanding sand shellsq
Wadley, Haydn
The dynamic response of edge clamped plates loaded by spherically expanding sand shellsq Kumar P and water saturated sand has been investigated, both experimentally and via a particle based simulation methodology. The spherically expanding sand shell is generated by detonating a sphere of explosive surrounded
Consent Order, Lawrence Livermore National National Security...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Lawrence Livermore National National Security, LLC - WCO-2010-01 Consent Order, Lawrence Livermore National National Security, LLC - WCO-2010-01 October 29, 2010 Issued to Lawrence...
Processes for making dense, spherical active materials for lithium-ion cells
Kang, Sun-Ho (Naperville, IL); Amine, Khalil (Downers Grove, IL)
2011-11-22
Processes are provided for making dense, spherical mixed-metal carbonate or phosphate precursors that are particularly well suited for the production of active materials for electrochemical devices such as lithium ion secondary batteries. Exemplified methods include precipitating dense, spherical particles of metal carbonates or metal phosphates from a combined aqueous solution using a precipitating agent such as ammonium hydrogen carbonate, sodium hydrogen carbonate, or a mixture that includes sodium hydrogen carbonate. Other exemplified methods include precipitating dense, spherical particles of metal phosphates using a precipitating agent such as ammonium hydrogen phosphate, ammonium dihydrogen phosphate, sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, or a mixture of any two or more thereof. Further provided are compositions of and methods of making dense, spherical metal oxides and metal phosphates using the dense, spherical metal precursors. Still further provided are electrodes and batteries using the same.
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on the Pajarito Plateau topic of inaugural lecture at Los Alamos National Laboratory January 4, 2013 Lecture series begins yearlong commemoration of 70th anniversary LOS...
Analysis of spherically symmetric black holes in Braneworld models
A. B. Pavan
2010-05-25
Research on black holes and their physical proprieties has been active on last 90 years. With the appearance of the String Theory and the Braneworld models as alternative descriptions of our Universe, the interest on black holes, in these context, increased. In this work we studied black holes in Braneworld models. A class of spherically symmetric black holes is investigaded as well its stability under general perturbations. Thermodynamic proprieties and quasi-normal modes are discussed. The black holes studied are the SM (zero mass) and CFM solutions, obtained by Casadio {\\it et al.} and Bronnikov {\\it et al.}. The geometry of bulk is unknown. However the Campbell-Magaard Theorem guarantees the existence of a 5-dimensional solution in the bulk whose projection on the brane is the class of black holes considered. They are stable under scalar perturbations. Quasi-normal modes were observed in both models. The tail behavior of the perturbations is the same. The entropy upper bound of a body absorved by the black holes studied was calculated. This limit turned out to be independent of the black hole parameters.
A Keplerian Limit to Static Spherical Spacetimes in Curvature Coordinates
Tyler J. Lemmon; Antonio R. Mondragon
2008-09-04
The problem of a test body in the Schwarzschild geometry is investigated in a Keplerian limit. Beginning with the Schwarzschild metric, a solution to the limited case of approximately elliptical (Keplerian) motion is derived in terms of trigonometric functions. This solution is similar in form to that derived from Newtonian mechanics, and includes first-order corrections describing three effects due to general relativity: precession; reduced radial coordinate; and increased eccentricity. The quantitative prediction of increased eccentricity may provide an additional observational test of general relativity. By analogy with Keplerian orbits, approximate orbital energy parameters are defined in terms of a relativistic eccentricity, providing first-order corrections to Newtonian energies for elliptical orbits. The first-order relativistic equation of orbit is demonstrated to be a limiting case of a very accurate self-consistent solution. This self-consistent solution is supported by exact numerical solutions to the Schwarzschild geometry, displaying remarkable agreement. A more detailed energy parameterization is investigated using the relativistic eccentricity together with the apsides derived from the relativistic effective potential in support of the approximate energy parameters defined using only first-order corrections. The methods and approximations describing this Keplerian limit are applied to more general static spherically-symmetric geometries. Specifically, equations of orbit and energy parameters are also derived in this Keplerian limit for the Reissner-Nordstr\\"{o}m and Schwarzschild-de Sitter metrics.
Octahedral spherical hohlraum and its laser arrangement for inertial fusion
Lan, Ke; He, Xian-Tu; Liu, Jie [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Zheng, Wudi; Lai, Dongxian [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)
2014-05-15
A recent publication [K. Lan et al., Phys. Plasmas 21, 010704 (2014)] proposed a spherical hohlraum with six laser entrance holes of octahedral symmetry at a specific hohlraum-to-capsule radius ratio of 5.14 for inertial fusion study, which has robust high symmetry during the capsule implosion and superiority on low backscatter without supplementary technology. This paper extends the previous one by studying the laser arrangement and constraints of octahedral hohlraum in detail. As a result, it has serious beam crossing at ?{sub L}?45°, and ?{sub L}=50° to 60° is proposed as the optimum candidate range for the golden octahedral hohlraum, here ?{sub L} is the opening angle that the laser quad beam makes with the Laser Entrance Hole (LEH) normal direction. In addition, the design of the LEH azimuthal angle should avoid laser spot overlapping on hohlraum wall and laser beam transferring outside hohlraum from a neighbor LEH. The octahedral hohlraums are flexible and can be applicable to diverse inertial fusion drive approaches. This paper also applies the octahedral hohlraum to the recent proposed hybrid indirect-direct drive approach.
Complete fusion of $^9$Be with spherical targets
Henning Esbensen
2010-03-02
The complete fusion of $^9$Be with $^{144}$Sm and $^{208}$Pb targets is calculated in the coupled-channels approach. The calculations include couplings between the 3/2$^-$, 5/2$^-$, and 7/2$^-$ states in the $K=3/2$ ground state rotational band of $^9$Be. It is shown that the $B(E2)$ values for the excitation of these states are accurately described in the rotor model. The interaction of the strongly deformed $^9$Be nucleus with a spherical target is calculated using the double-folding technique and the effective M3Y interaction, which is supplemented with a repulsive term that is adjusted to optimize the fit to the data for the $^{144}$Sm target. The complete fusion is described by in-going-wave boundary conditions. The decay of the unbound excited states in $^9$Be is considered explicitly in the calculations by using complex excitation energies. The model gives an excellent account of the complete fusion (CF) data for $^9$Be+$^{144}$Sm, and the cross sections for the decay of the excited states are in surprisingly good agreement with the incomplete fusion (ICF) data. Similar calculations for $^9$Be+$^{208}$Pb explain the total fusion data at high energies but fail to explain the CF data, which are suppressed by 20%, and the calculated cross section for the decay of excited states is a factor of three smaller than the ICF data at high energies. Possible reasons for these discrepancies are discussed.
Skyrme RPA for spherical and axially symmetric nuclei
Anton Repko; Jan Kvasil; V. O. Nesterenko; P. -G. Reinhard
2015-10-05
Random Phase Approximation (RPA) is the basic method for calculation of excited states of nuclei over the Hartree-Fock ground state, suitable also for energy density functionals (EDF or DFT). We developed a convenient formalism for expressing densities and currents in a form of reduced matrix elements, which allows fast calculation of spectra for spherical nuclei. All terms of Skyrme functional were taken into account, so it is possible to calculate electric, magnetic and vortical/toroidal/compression transitions and strength functions of any multipolarity. Time-odd (spin) terms in Skyrme functional become important for magnetic M1 and isovector toroidal E1 transitions. It was also found that transition currents in pygmy region (low-lying part of E1 resonance) exhibit isoscalar toroidal flow, so the previously assumed picture of neutron-skin vibration is not the only mechanism present in pygmy transitions. RPA calculations with heavy axially-symmetric nuclei now become feasible on ordinary PC. Detailed formulae for axial Skyrme RPA are given. Some numerical results are shown in comparison with the approximate approach of separable RPA, previously developed in our group for fast calculation of strength functions.
Energy-momentum Prescriptions in General Spherically Symmetric Space-times
Saeed Mirshekari; Amir M. Abbassi
2014-11-29
Einstein, Landau-Lifshitz, Papapetrou, Weinberg, and M{\\o}ller energy-momentum prescriptions in general spherically symmetric space-times are investigated. It is shown that for two special but not unusual classes of general spherically symmetric space-times several energy-momentum prescriptions in Schwarzschild Cartesian coordinates lead to some coincidences in energy distribution. It is also obtained that for a special class of spherically symmetric metrics M{\\o}ller and Einstein energy-momentum prescriptions give the same result for energy distribution if and only if it has a specific dependence on radial coordinate.
PREPARED FOR THE U.S. DEPARTMENT OF ENERGY, UNDER CONTRACT DE-AC02-76CH03073
PREPARED FOR THE U.S. DEPARTMENT OF ENERGY, UNDER CONTRACT DE-AC02-76CH03073 PRINCETON PLASMA of the Effect of Compressional Alfvén Modes on Thermal Transport in the National Spherical Torus Experiment by E by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its
House FY-2014 Omnibus Appropriations Bill Language for DOE Office of Science
-II) Experimental Tools. For facilities operations, the agreement provides $778,785,000 for Synchrotron Radiation BioEnergy Research Centers, $5,000,000 to continue nuclear medicine research with human applications, the agreement provides $62,550,000 for the National Spherical Torus Experiment, of which $22
Ramp-up of CHI Initiated Plasmas on NSTX
Mueller, D; Bell, R E; LeBlanc, B; Roquemore, A L; Raman, R; Jarboe, T R; Nelson, B A
2009-10-29
Experiments on the National Spherical Torus (NSTX) have now demonstrated flux savings using transient coaxial helicity injection (CHI). In these discharges, the discharges initiated by CHI are ramped up with an inductive transformer and exhibit higher plasma current than discharges without the benefit of CHI initiation.
National RF Test Facility as a multipurpose development tool
McManamy, T.J.; Becraft, W.R.; Berry, L.A.; Blue, C.W.; Gardner, W.L.; Haselton, H.H.; Hoffman, D.J.; Loring, C.M. Jr.; Moeller, F.A.; Ponte, N.S.
1983-01-01
Additions and modifications to the National RF Test Facility design have been made that (1) focus its use for technology development for future large systems in the ion cyclotron range of frequencies (ICRF), (2) expand its applicability to technology development in the electron cyclotron range of frequencies (ECRF) at 60 GHz, (3) provide a facility for ELMO Bumpy Torus (EBT) 60-GHz ring physics studies, and (4) permit engineering studies of steady-state plasma systems, including superconducting magnet performance, vacuum vessel heat flux removal, and microwave protection. The facility will continue to function as a test bed for generic technology developments for ICRF and the lower hybrid range of frequencies (LHRF). The upgraded facility is also suitable for mirror halo physics experiments.
PREPARED FORTHE U.S. DEPARTMENT OF ENERGY, UNDER CONTRACT DEAC0276CH03073
of the ``Spherical Torus'' plasma [1]. This idea is in accordance with the US Department of Energy ``Roadmap
A classification of spherically symmetric self-similar dust models
B. J. Carr
2000-03-02
We classify all spherically symmetric dust solutions of Einstein's equations which are self-similar in the sense that all dimensionless variables depend only upon $z\\equiv r/t$. We show that the equations can be reduced to a special case of the general perfect fluid models with equation of state $p=\\alpha \\mu$. The most general dust solution can be written down explicitly and is described by two parameters. The first one (E) corresponds to the asymptotic energy at large $|z|$, while the second one (D) specifies the value of z at the singularity which characterizes such models. The E=D=0 solution is just the flat Friedmann model. The 1-parameter family of solutions with z>0 and D=0 are inhomogeneous cosmological models which expand from a Big Bang singularity at t=0 and are asymptotically Friedmann at large z; models with E>0 are everywhere underdense relative to Friedmann and expand forever, while those with E0 ones. The 2-parameter solutions with D>0 again represent inhomogeneous cosmological models but the Big Bang singularity is at $z=-1/D$, the Big Crunch singularity is at $z=+1/D$, and any particular solution necessarily spans both z0. While there is no static model in the dust case, all these solutions are asymptotically ``quasi-static'' at large $|z|$. As in the D=0 case, the ones with $E \\ge 0$ expand or contract monotonically but the latter may now contain a naked singularity. The ones with E<0 expand from or recollapse to a second singularity, the latter containing a black hole.
Office of Environmental Management (EM)
a modified United Nations Test for Oxidizing Solids protocol. * 2010 burn-rate tests at New Mexico Tech performed on two types of surrogates of the buried Rocky Flats salt...
Mazlish, Bruce
Globalism and globalization have been seen as competitors to other allegiances, namely regionalism and nationalism. A look at recent efforts at reconceptualizing global history in China, Korea and the U.S., however, suggests ...
Hydrodynamic growth of shell modulations in the deceleration phase of spherical direct. Se´guin Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge .2 The unstable growth of target nonuniformities is the most significant factor disrupting
Design of a spherical vehicle with flywheel momentum storage for high torque capabilities
Schroll, Gregory C. (Gregory Cordner)
2008-01-01
A novel method for supplementing the propulsion of a spherical ground vehicle was conceived and developed. The addition of angular momentum storage via counter-rotating control moment gyroscopes is proposed in order to ...
Development of a Thermodynamic Model for Fluids Confined in Spherical Pores
D'Lima, Michelle Lynn
2014-07-18
, which are abundant in Qatar as some of the major components of natural gas. Both pure component and binary mixture literature data were compiled. 25 Table 3: Spherical Zeolite Classification Structure Name ASV ASU-7 ATN MAPO-39 DDR...
True Polar Wander: linking Deep and Shallow Geodynamics to Hydro-and Bio-Spheric Hypotheses
True Polar Wander: linking Deep and Shallow Geodynamics to Hydro- and Bio-Spheric Hypotheses T. D on the bulk solid Earth over longer tirnescales 565 #12;566 Linking Deep and Shallow Geodynamics to Hydro
A two-phase spherical electric machine for generating rotating uniform magnetic fields
Lawler, Clinton T. (Clinton Thomas)
2007-01-01
This thesis describes the design and construction of a novel two-phase spherical electric machine that generates rotating uniform magnetic fields, known as a fluxball machine. Alternative methods for producing uniform ...
Response of grooved composites to transversely distributed and localized spherical contact loadings
Jeffrey, Holly K
2011-01-01
The response of a grooved composite specimen to two contact loading situations is studied; load applied via a transversely oriented cylindrical indenter and via a localized spherical ball-ended indenter. The philosophy of ...
Laverty, Stephen Michael
2005-01-01
This thesis looks at the hydrodynamics of spherical projectiles impacting the free surface using a unique experimental WebLab facility. Experiments were performed to determine the force impact coefficients of spheres and ...
Effect of plasma parameters on growth and field emission properties of spherical carbon nanotube tip
Sharma, Suresh C.; Tewari, Aarti
2011-06-15
The effect of plasma parameters (e.g., electron density and temperature, ion density and temperature, neutral atom density and temperature) on the growth (without a catalyst), structure, and field emission properties of a spherical carbon nanotube (CNT) tip has been theoretically investigated. A theoretical model of charge neutrality, including the kinetics of electrons, positively charged ions, and neutral atoms and the energy balance of the various species in plasma, has been developed. Numerical calculations of the radius of the spherical CNT tip for different CNT number densities and plasma parameters have been carried out for the typical glow discharge plasma parameters. It is found that upon an increase in the CNT number density and plasma parameters, the radius of the spherical CNT tip decreases, and consequently the field emission factor for the spherical CNT tip increases.
Disruptions, Disruptivity, and Safer Operating Windows in the...
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of Publication: United States Language: English Subject: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY Disruptions, High-beta Plasmas,MHD Instability, Spherical Torus, Spherical...
Reduced model prediction of electron temperature profiles in...
Office of Scientific and Technical Information (OSTI)
FUSION TECHNOLOGY Confinement; H-mode Plasma Confinement; Spherical Torus; Spherical Tokamak; Stability, Microinstability; Tokamaks, NSTX; Transport Phenomena Word Cloud More...
Geometric Design of Spherical Serial Chains with Curvature Constraints in the Environment
Tolety, Anurag Bharadwaj
2012-10-19
2011 Major Subject: Electrical Engineering GEOMETRIC DESIGN OF SPHERICAL SERIAL CHAINS WITH CURVATURE CONSTRAINTS IN THE ENVIRONMENT A Thesis by ANURAG BHARADWAJ TOLETY Submitted to the O ce of Graduate Studies of Texas A&M University in partial... Georghiades August 2011 Major Subject: Electrical Engineering iii ABSTRACT Geometric Design of Spherical Serial Chains with Curvature Constraints in the Environment. (August 2011) Anurag Bharadwaj Tolety, B. Tech., Indian Institute of Technology...
Newtonian wormholes with spherical symmetry and tidal forces on test particles
Paulo Luz; José P. S. Lemos
2015-05-23
A spherically symmetric wormhole in Newtonian gravitation in curved space, enhanced with a connection between the mass density and the Ricci scalar, is presented. The wormhole, consisting of two connected asymptotically flat regions, inhabits a spherically symmetric curved space. The gravitational potential, gravitational field and the pressure that supports the fluid that permeates the Newtonian wormhole are computed. Particle dynamics and tidal effects in this geometry are studied. The possibility of having Newtonian black holes in this theory is sketched.
Investigation of Gas Solid Fluidized Bed Dynamics with Non-Spherical Particles
Choudhuri, Ahsan
2013-06-30
One of the largest challenges for 21st century is to fulfill global energy demand while also reducing detrimental impacts of energy generation and use on the environment. Gasification is a promising technology to meet the requirement of reduced emissions without compromising performance. Coal gasification is not an incinerating process; rather than burning coal completely a partial combustion takes place in the presence of steam and limited amounts of oxygen. In this controlled environment, a chemical reaction takes place to produce a mixture of clean synthetic gas. Gas-solid fluidized bed is one such type of gasification technology. During gasification, the mixing behavior of solid (coal) and gas and their flow patterns can be very complicated to understand. Many attempts have taken place in laboratory scale to understand bed hydrodynamics with spherical particles though in actual applications with coal, the particles are non-spherical. This issue drove the documented attempt presented here to investigate fluidized bed behavior using different ranges of non-spherical particles, as well as spherical. For this investigation, various parameters are controlled that included particle size, bed height, bed diameter and particle shape. Particles ranged from 355 µm to 1180 µm, bed diameter varied from 2 cm to 7 cm, two fluidized beds with diameters of 3.4 cm and 12.4 cm, for the spherical and non-spherical shaped particles that were taken into consideration. Pressure drop was measured with increasing superficial gas velocity. The velocity required in order to start to fluidize the particle is called the minimum fluidization velocity, which is one of the most important parameters to design and optimize within a gas-solid fluidized bed. This minimum fluidization velocity was monitored during investigation while observing variables factors and their effect on this velocity. From our investigation, it has been found that minimum fluidization velocity is independent of bed height for both spherical and non-spherical particles. Further, it decrease with decreasing particle size and decreases with decreasing bed diameter. Shadow sizing, a non-intrusive imaging and diagnostic technology, was also used to visualize flow fields inside fluidized beds for both spherical and non- spherical particles and to detect the particle sizes.
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Density- and wavefunction-normalized Cartesian spherical harmonics for l ? 20
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Michael, J. Robert; Volkov, Anatoliy
2015-03-01
The widely used pseudoatom formalism in experimental X-ray charge-density studies makes use of real spherical harmonics when describing the angular component of aspherical deformations of the atomic electron density in molecules and crystals. The analytical form of the density-normalized Cartesian spherical harmonic functions for up to l ? 7 and the corresponding normalization coefficients were reported previously by Paturle & Coppens. It was shown that the analytical form for normalization coefficients is available primarily forl ? 4. Only in very special cases it is possible to derive an analytical representation of the normalization coefficients for 4 l ? 7.more »In most cases for l > 4 the density normalization coefficients were calculated numerically to within seven significant figures. In this study we review the literature on the density-normalized spherical harmonics, clarify the existing notations, use the Paturle–Coppens method in the Wolfram Mathematicasoftware to derive the Cartesian spherical harmonics for l ? 20 and determine the density normalization coefficients to 35 significant figures, and computer-generate a Fortran90 code. The article primarily targets researchers who work in the field of experimental X-ray electron density, but may be of some use to all who are interested in Cartesian spherical harmonics.« less
Modeling Ion-Exchange Processing With Spherical Resins For Cesium Removal
Hang, T.; Nash, C. A.; Aleman, S. E.
2012-09-19
The spherical Resorcinol-Formaldehyde and hypothetical spherical SuperLig(r) 644 ion-exchange resins are evaluated for cesium removal from radioactive waste solutions. Modeling results show that spherical SuperLig(r) 644 reduces column cycling by 50% for high-potassium solutions. Spherical Resorcinol Formaldehyde performs equally well for the lowest-potassium wastes. Less cycling reduces nitric acid usage during resin elution and sodium addition during resin regeneration, therefore, significantly decreasing life-cycle operational costs. A model assessment of the mechanism behind ''cesium bleed'' is also conducted. When a resin bed is eluted, a relatively small amount of cesium remains within resin particles. Cesium can bleed into otherwise decontaminated product in the next loading cycle. The bleed mechanism is shown to be fully isotherm-controlled vs. mass transfer controlled. Knowledge of residual post-elution cesium level and resin isotherm can be utilized to predict rate of cesium bleed in a mostly non-loaded column. Overall, this work demonstrates the versatility of the ion-exchange modeling to study the effects of resin characteristics on processing cycles, rates, and cold chemical consumption. This evaluation justifies further development of a spherical form of the SL644 resin.
Truthing the stretch: Non-perturbative cosmological realizations with multiscale spherical collapse
Neyrinck, Mark C
2015-01-01
Here we present a simple, parameter-free, non-perturbative algorithm that gives low-redshift cosmological particle realizations accurate to few-Megaparsec scales, called muscle (MUltiscale Spherical ColLapse Evolution). It has virtually the same cost as producing N-body-simulation initial conditions, since it works with the 'stretch' parameter {\\psi}, the Lagrangian divergence of the displacement field. It promises to be useful in quickly producing mock catalogs, and to simplify computationally intensive reconstructions of galaxy surveys. muscle applies a spherical-collapse prescription on multiple Gaussian-smoothed scales. It achieves higher accuracy than perturbative schemes (Zel'dovich and 2LPT), and, by including the void-in-cloud process (voids in large-scale collapsing regions), solves problems with a single-scale spherical-collapse scheme. Additionally, we show the behavior of {\\psi} for different morphologies (voids, walls, filaments, and haloes). A Python code to produce these realizations is availab...
On the generation of triaxiality in the collapse of cold spherical self-gravitating systems
Labini, Francesco Sylos; Joyce, Michael
2015-01-01
Initially cold and spherically symmetric self-gravitating systems may give rise to a virial equilibrium state which is far from spherically symmetric, and typically triaxial. We focus here on how the degree of symmetry breaking in the final state depends on the initial density profile. We note that the most asymmetric structures result when, during the collapse phase, there is a strong injection of energy preferentially into the particles which are localized initially in the outer shells. These particles are still collapsing when the others, initially located in the inner part, are already re-expanding; the motion of particles in a time varying potential allow them to gain kinetic energy --- in some cases enough to be ejected from the system. We show that this mechanism of energy gain amplifies the initial small deviations from perfect spherical symmetry due to finite $N$ fluctuations. This amplification is more efficient when the initial density profile depends on radius, because particles have a greater spr...
National Institutes of Health Current National Institute
Rau, Don C.
Library of Medicine John E. Fogarty International Center for Advanced Study in National Center National Institute of Nursing Research National Library of Medicine John E. Fogarty International CenterNational Institutes of Health Current National Institute of Arthritis and Musculoskeletal and Skin
Use of spherically bent crystals to diagnose wire array z pinches
Shelkovenko, T.A.; Pikuz, S.A.; Hammer, D.A.; Ampleford, D.J.; Bland, S.N.; Bott, S.C.; Chittenden, J.P.; Lebedev, S.V.
2004-10-01
Spherically bent mica and quartz crystals have provided time-integrated spectra and monochromatic images in self-radiation of wire array z-pinch implosions on the MAGPIE generator (1 MA, 240 ns) at Imperial College. Diagnostics based on spherically bent crystals offer higher efficiencies than those based on flat or convex dispersion elements, allowing positioning far from the pinch with good debris shielding. A mica crystal spectrometer produced an image of the pinch in each emission line with about 100 {mu}m axial resolution. Combining the results of monochromatic imaging and spectra confirmed the presence of bright spots, probably generated by energetic electrons inside the pinch.
Magneto-inertial fusion with laser compression of a magnetized spherical target
Kostyukov, I. Yu., E-mail: kost@appl.sci-nnov.ru [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation); Ryzhkov, S. V., E-mail: ryzhkov@power.bmstu.ru [Bauman Moscow State Technical University (Russian Federation)
2011-12-15
The paper is devoted to the principles of magneto-inertial fusion and laser-plasma methods of generation of a Megagauss field during spherical implosion of a magnetized target. A model based on a magnetic confinement system, namely, a cusp configuration with inertial compression of the target by a laser driver, is developed. The dynamics of plasma in a cusp compressed under the effect of laser beams is precalculated. Analytical and numerical estimates of the particle number and magnetic field intensity during magneto-inertial plasma compression are obtained. The problems of irradiation of a spherically closed volume by a high-energy laser pulse are discussed.
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMass map shinesSolar Photovoltaic Solar PhotovoltaicBWXT Y-12 is preserving Y-12'sNational
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration wouldMass map shinesSolar Photovoltaic Solar PhotovoltaicBWXT Y-12 is preserving Y-12'sNational
Office of Scientific and Technical Information (OSTI)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefield MunicipalTechnical Report: AchievementsTemperatures Year 6 -FINALEnergy,Pacific Mort hwest National
National System Templates: Building Sustainable National Inventory...
to: navigation, search Tool Summary LAUNCH TOOL Name: National System Templates: Building Sustainable National Inventory Management Systems AgencyCompany Organization: United...
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National Nuclear Security Administration (NNSA)
nuclear weapons Bay Area national labs team to tackle long-standing automotive hydrogen storage challenge Sandia National Laboratories chemist Mark Allendorf, shown here at...
Tazaki, Fumie; Ueda, Yoshihiro; Terashima, Yuichi; Mushotzky, Richard F.; Tombesi, Francesco
2013-07-20
We present the results from broadband X-ray spectral analysis of 3C 206 and PKS 0707-35 with Suzaku and Swift/BAT, two of the most luminous unobscured and obscured radio-loud active galactic nuclei (AGNs) with hard X-ray luminosities of 10{sup 45.5} erg s{sup -1} and 10{sup 44.9} erg s{sup -1} (14-195 keV), respectively. Based on the radio core luminosity, we estimate that the X-ray spectrum of 3C 206 contains a significant ({approx}60% in the 14-195 keV band) contribution from the jet, while it is negligible in PKS 0707-35. We can successfully model the spectra with the jet component (for 3C 206), the transmitted emission, and two reflection components from the torus and the accretion disk. The reflection strengths from the torus are found to be R{sub torus}({identical_to} {Omega}/2{pi}) = 0.29 {+-} 0.18 and 0.41 {+-} 0.18 for 3C 206 and PKS 0707-35, respectively, which are smaller than those in typical Seyfert galaxies. Utilizing the torus model by Ikeda et al., we quantify the relation between the half-opening angle of a torus ({theta}{sub oa}) and the equivalent width of an iron-K line. The observed equivalent width of 3C 206, < 71 eV, constrains the column density in the equatorial plane to N{sub H}{sup eq} <10{sup 23} cm{sup -2}, or the half-opening angle to {theta}{sub oa} > 80 Degree-Sign if N{sub H}{sup eq} =10{sup 24} cm{sup -2} is assumed. That of PKS 0707-35, 72 {+-} 36 eV, is consistent with N{sub H}{sup eq} {approx}10{sup 23} cm{sup -2}. Our results suggest that the tori in luminous radio-loud AGNs are only poorly developed. The trend is similar to that seen in radio-quiet AGNs, implying that the torus structure is not different between AGNs with jets and without jets.
Spheree: A 3D Perspective-Corrected Interactive Spherical Scalable Display Ferreira, F.q
British Columbia, University of
models can be exported or printed on a 3D printer. Other related 3D displays include: 1. pCubee [StavnessSpheree: A 3D Perspective-Corrected Interactive Spherical Scalable Display Ferreira, F.q , Cabral & U of British Columbia (a) (b) (c) (d) Figure 1: (a) A snowglobe; (b) a fish-tank animation; (c) a 3D
Spheree: A 3D Perspective-Corrected Interactive Spherical Scalable Display Ferreira, F.q
British Columbia, University of
in their applications or even print them with a 3D printer. Thus, Spheree plays a key role in realizing a completeSpheree: A 3D Perspective-Corrected Interactive Spherical Scalable Display Ferreira, F.q , Cabral to support head-coupled rendering to provide parallax-based 3D depth cues. Spheree is relatively compact
Fusion Engineering and Design 5152 (2000) 325330 Nuclear issues and analysis for ARIES spherical and
California at San Diego, University of
2000-01-01
Fusion Engineering and Design 5152 (2000) 325330 Nuclear issues and analysis for ARIES spherical the key nuclear parameters for both designs. Preceding the 3-D analysis, a series of parametric 1-D analysis using the DANTSYS code [4] was established to guide the design pro- cess. The data library
November 16, 1999 1. Drag force on non spherical particles. (25 points)
McCready, Mark J.
ChEg 355 Fall 1999 Test #2 November 16, 1999 1. Drag force on non spherical particles. (25 points) Recall that the Stokes' law drag relation for a sphere in creeping flow is: FD = 6 µ R U, where µ is the fluid viscosity, R is the radius of the sphere, and U is the terminal velocity. It was mentioned
Advanced Fluid Dynamics 2014 Sheet 5 Stokes flow around spherical particles
Hogg, Andrew
with no body force, where µ denotes the dynamic viscosity. Show that the stress tensor is given by ij = -2µ Ak xk ij + 2µ 2 xixj + xk 2 Ak xixj . (2) (b) Now consider the flow past a stationary sphere of radius the drag on the particle. 2. (a) Axisymmetric flow may be expressed in terms of spherical polar coordinates
Design and Present status of Steady-state spherical tokamak, QUEST
Princeton Plasma Physics Laboratory
Design and Present status of Steady-state spherical tokamak, QUEST K.Hanada, H.Zushi, K.N.Sato, K Component Interactions in Steady State Magnetic Fusion Devices at NIFS #12;Japanese Collaborators and Map knowledge QUEST #12;Why steady-state ? Time (sec) Hsupply(1020 H) wall pumping ~4 x 1017 [H/m2s] High
Chen, Zheng [State Key Laboratory for Turbulence and Complex Systems, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871 (China)
2011-02-15
Large discrepancies among the laminar flame speeds and Markstein lengths of methane/air mixtures measured by different researchers using the same constant-pressure spherical flame method are observed. As an effort to reduce these discrepancies, one linear model (LM, the stretched flame speed changes linearly with the stretch rate) and two non-linear models (NM I and NM II, the stretched flame speed changes non-linearly with the stretch rate) for extracting the laminar flame speed and Markstein length from propagating spherical flames are investigated. The accuracy and performance of the LM, NM I, and NM II are found to strongly depend on the Lewis number. It is demonstrated that NM I is the most accurate for mixtures with large Lewis number (positive Markstein length) while NM II is the most accurate for mixtures with small Lewis number (negative Markstein length). Therefore, in order to get accurate laminar flame speed and Markstein length from spherical flame experiments, different non-linear models should be used for different mixtures. The validity of the theoretical results is further demonstrated by numerical and experimental studies. The results of this study can be used directly in spherical flame experiments measuring the laminar flame speed and Markstein length. (author)
Comment on "Static and spherically symmetric black holes in f(R) theories"
S. Habib Mazharimousavi; M. Halilsoy
2012-10-17
We consider the interesting "near-horizon test" reported in (PRD84, 084006(2011), arXiv:1107.5727) for any static, spherically symmetric (SSS) black hole solution admitted in f(R) gravity. Before adopting the necessary conditions for the test, however, revisions are needed as we point out in this Comment.
Jablonowski, Christiane
Three Dimensional Adaptive Mesh Refinement on a Spherical Shell for Atmospheric Models for Atmospheric Research 1. Introduction One of the most important advances needed in global climate models of this project is a parallel adaptive grid library, which is currently under development at the University
Water-like solvation thermodynamics in a spherically symmetric solvent model
Buldyrev, Sergey
Water-like solvation thermodynamics in a spherically symmetric solvent model with two. The Jagla fluid has been recently shown to possess water-like structural, dynamic, and thermodynamic and thereby show that the Jagla fluid also displays water-like solvation thermodynamics. We further find low
Quantum chaos for the radially vibrating spherical billiard Richard L. Liboff and Mason A. Porter
Porter, Mason A.
Quantum chaos for the radially vibrating spherical billiard Richard L. Liboff and Mason A. Porter Chaos 17, 023116 (2007); 10.1063/1.2731307 Quantum Chaos in Billiards Comput. Sci. Eng. 9, 60 (2007); 10.1063/1.1322028 Vibrating soap films: An analog for quantum chaos on billiards Am. J. Phys. 66, 601 (1998); 10
Summation over histories for a particle in spherical orbit around a black hole
Bernido, C.C.; Aguarte, G.
1997-08-01
An exact path integral treatment of a relativistic scalar particle in a spherical orbit around a Reissner-Nordstr{umlt o}m and Schwarzschild black hole is presented. A closed form for the Green function and the energy spectrum are obtained. {copyright} {ital 1997} {ital The American Physical Society}
INVERSION OF SPHERICAL MEANS AND THE WAVE EQUATION IN EVEN DIMENSIONS.
Finch, David
. spherical means, thermoacoustic tomography, wave equation, back-projection AMS subject classifications. 35R interest in the subject was provoked by the new medical imaging technologies called thermoacoustic of radiofrequency or optical energy which causes rapid (though small in magnitude) thermal expansion which generates
Spherical distribution vectors Aloysius G. Helminck (loek@math.ncsu.edu)
Helminck, Aloysius G. "Loek"
of the Riemannian symmetric spaces e.g. (van Dijk and Pasquale, 1999),(Camporesi, 1997) and his contribution varieties turned out to be that of an H-invariant spherical distribu- tion, see e.g. (van Dijk and Poel/G) decomposes multiplicity free. For a survey of various examples of such pairs, we refer to (van Dijk, 1994
The giant luminous arc Statistics. II. spherical lens models based on ROSAT HRI data
Kohji Molikawa; Makoto Hattori; Jean-Paul Kneib; Kazuyuki Yamashita
1999-09-10
We present ROSAT HRI X-ray observations of all the galaxy clusters in the Le F\\`evre et al. arc survey sample in order to study the spatial distribution of the intra-cluster medium, and examine the expected number of giant luminous arcs for the sample using two spherically symmetric lens models constrained by our X-ray data.
Chen, Zhongping
electrode whose electrostatic gap width, defined during the glass blowing process, is not limited deformation of metallic glasses to achieve spherical structures has been explored by using a blow batch fabrication glass-blowing process developed at the UC Irvine Microsystems Laboratory allows
SPHERICAL RUBIDIUM VAPOR CELLS FABRICATED BY MICRO GLASS BLOWING E. Jesper Eklund1
Chen, Zhongping
SPHERICAL RUBIDIUM VAPOR CELLS FABRICATED BY MICRO GLASS BLOWING E. Jesper Eklund1 , Andrei M, Boulder, CO, USA ABSTRACT This paper presents an application of micro glass blowing, in which multiple atomic apparatuses. Although glass blowing has been used to achieve millimeter-scale cells in the past
Analytical Solution of the Forward Displacement Problem for Spherical Parallel Manipulators
Rodriguez, Jose
2012-01-01
In this paper, an analytical method that solves the forward displacement problem of several common spherical parallel manipulators (SPMs) is presented. The method uses the the quaternion algebra to restate the problem as a system of four quadrics in four variables and uses an algebraic geometry result by Dixon from 1908 to solve. In addition, a case study is presented for a specific SPM.
Broader source: Energy.gov [DOE]
This EA evaluates the environmental impacts of the proposal to support fusion physics development and technology, by providing an experimental device to investigate the confinement and performance...
web page: http://w3.pppl.gov/~ zakharov Ignited Spherical Tokamaks for development of power reactor1
Zakharov, Leonid E.
web page: http://w3.pppl.gov/~ zakharov Ignited Spherical Tokamaks for development of power reactor-0451 International Workshop on Experimental Performance of KTM Tokamak, Oct. 10, 2005, Astana, Kazakhstan, 2005 1 development, and the only candidates are spherical tokamaks (ST). For the purposes of the first wall R
Walter, M.Todd
The spherically symmetric droplet burning characteristics of Jet-A and biofuels derived from the biofuels due to its higher aromatic content. " Droplet burning rates of camelina and tallow HRJ fuel Available online 1 March 2013 Keywords: Alternative jet fuel Hydroprocessed biofuel Spherically symmetric
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 OutreachProductswsicloudwsiclouddenDVA N C E D B L O OLaura| National2.11 Print3.30.2LabBudgetBehavior
Calibration of Spherically Bent Crystals used in X-Ray Spectroscopy...
Office of Scientific and Technical Information (OSTI)
NM. Research Org: Sandia National Laboratories Sponsoring Org: USDOE National Nuclear Security Administration (NNSA) Country of Publication: United States Language: English...
T. Thiemann
1999-10-04
We present here the canonical treatment of spherically symmetric (quantum) gravity coupled to spherically symmetric Maxwell theory with or without a cosmological constant. The quantization is based on the reduced phase space which is coordinatized by the mass and the electric charge as well as their canonically conjugate momenta, whose geometrical interpretation is explored. The dimension of the reduced phase space depends on the topology chosen, quite similar to the case of pure (2+1) gravity. We also compare the reduced phase space quantization to the algebraic quantization. Altogether, we observe that the present model serves as an interesting testing ground for full (3+1) gravity. We use the new canonical variables introduced by Ashtekar which simplifies the analysis tremendously.
T. Thiemann
1999-10-04
We extend here the canonical treatment of spherically symmetric (quantum) gravity to the most simple matter coupling, namely spherically symmetric Maxwell theory with or without a cosmological constant. The quantization is based on the reduced phase space which is coordinatized by the mass and the electric charge as well as their canonically conjugate momenta, whose geometrical interpretation is explored. The dimension of the reduced phase space depends on the topology chosen, quite similar to the case of pure (2+1) gravity. We investigate several conceptual and technical details that might be of interest for full (3+1) gravity. We use the new canonical variables introduced by Ashtekar, which simplifies the analysis tremendously.
High-resolution monochromatic x-ray imaging system based on spherically bent crystals
Aglitskiy, Y.; Lehecka, T.; Obenschain, S.; Bodner, S.; Pawley, C.; Gerber, K.; Sethian, J.; Brown, C.M.; Seely, J.; Feldman, U.; Holland, G.
1998-08-01
We have developed an improved x-ray imaging system based on spherically curve crystals. It is designed and used for diagnostics of targets ablatively accelerated by the Nike KrF laser. A spherically curved quartz crystal (2d=6.687 {Angstrom}, R=200 mm) has been used to produce monochromatic backlit images with the He-like Si resonance line (1865 eV) as the source of radiation. The spatial resolution of the x-ray optical system is 1.7 {mu}m in selected places and 2{endash}3 {mu}m over a larger area. Time-resolved backlit monochromatic images of polystyrene planar targets driven by the Nike facility have been obtained with a spatial resolution of 2.5 {mu}m in selected places and 5 {mu}m over the focal spot of the Nike laser. {copyright} 1998 Optical Society of America
High resolution monochromatic X-ray imaging system based on spherically bent crystals
Aglitskiy, Y.; Lehecka, T.; Obenschain, S.; Bodner, S.; Pawley, C.; Gerber, K.; Sethian, J.; Brown, C. M.; Seely, J.; Feldman, U.; Holland, G.
1997-05-05
We have developed a new X-ray imaging system based on spherically curved crystals. It is designed and used for diagnostics of targets ablatively accelerated by the Nike KrF laser. The imaging system is used for plasma diagnostics of the main target and for characterization of potential backlighters. A spherically curved quartz crystal (2d=6.687 A, R=200 mm) is used to produce monochromatic backlit images with the He-like Si resonance line (1865 eV) as the source of radiation. The spatial resolution of the X-ray optical system is 3-4 {mu}m. Time resolved backlit monochromatic images of CH planar targets driven by the Nike facility have been obtained with 6-7 {mu}m spatial resolution.
High resolution monochromatic X-ray imaging system based on spherically bent crystals
Aglitskiy, Y.; Lehecka, T.; Obenschain, S.; Bodner, S.; Pawley, C.; Gerber, K.; Sethian, J.; Brown, C.M.; Seely, J.; Feldman, U.; Holland, G.
1997-05-01
We have developed a new X-ray imaging system based on spherically curved crystals. It is designed and used for diagnostics of targets ablatively accelerated by the Nike KrF laser [1,2]. The imaging system is used for plasma diagnostics of the main target and for characterization of potential backlighters. A spherically curved quartz crystal (2d=6.687{Angstrom}, R=200mm) is used to produce monochromatic backlit images with the He-like Si resonance line (1865 eV) as the source of radiation. The spatial resolution of the X-ray optical system is 3{endash}4 {mu}m. Time resolved backlit monochromatic images of CH planar targets driven by the Nike facility have been obtained with 6{endash}7 {mu}m spatial resolution. {copyright} {ital 1997 American Institute of Physics.}
Packing of softly repulsive particles in a spherical box - a generalised Thomson problem
A. Mughal
2013-06-12
We study the (near or close to) ground state distribution of N softly repelling particles trapped in the interior of a spherical box. The charges mutually interact via an inverse power law potential of the form $1/r^\\gamma$. We study three regimes in which the charges form an single spherical shell at the edge of the box ($\\gamma=1$), a series of concentric shells of increasing density ($\\gamma=2$) and $\\gamma=12$ for which the charges form shells with a more uniform charge distribution. We conduct numerical simulations for clusters containing up to 5000 charges and compare charge density across the system with continuum limit results. The agreement between numerical (discrete) results and the continuum limit is found to improve with increasing N.
Ultra-directional super-scattering of homogenous spherical particles with radial anisotropy
Liu, Wei
2015-01-01
We study the light scattering of homogenous radially-anisotropic spherical particles. It is shown that radial anisotropy can be employed to tune effectively the electric resonances, and thus enable flexible overlapping of electric and magnetic dipoles of various numbers, which leads to unidirectional forward super-scattering at different spectral positions. We further reveal that through adjusting the radial anisotropy parameters, electric and magnetic resonances of higher orders can be also made overlapped, thus further collimating the forward scattering lobes. The ultra-directional super-scattering we have obtained with individual homogenous radially anisotropic spherical particles may shed new light to the design of compact and efficient nanoantennas, which may find various applications in solar cells, bio-sensing and many other antenna based researches.
Gravitational and electric energies in the collapse of a spherical thin-shell capacitor
Remo Ruffini; She-Sheng Xue
2013-07-25
We adopt a simplified model describing the collapse of a spherical thin-shell capacitor to give an analytical description how gravitational energy is converted to both kinetic and electric energies in the gravitational collapse. It is shown that (i) averaged kinetic and electric energies are the same order, about an half of gravitational energy of spherical thin-shell capacitor in the collapse; (ii) caused by radiating and rebuilding electric energy, the gravitational collapse undergoes a sequence of "on and off" hopping steps in the microscopic Compton scale. Although the collapse process is still continuous in terms of macroscopic scales, it is slowed down as the kinetic energy is reduced and collapsing time is about an order of magnitude larger than that of the collapse process eliminating electric processes.
Marushka, Viktor; Zabeida, Oleg Martinu, Ludvik
2014-11-01
The uniformity of ion density is critical for applications relying on the ion assisted deposition technique for the fabrication of the high quality thin films. The authors propose and describe here a method allowing one to calculate the ion density distribution on spherical substrate holders under stationary and rotating conditions for different positions of the ion source. The ion beam shape was approximated by a cos{sup n} function, and the ion current density was represented by a function inversely proportional to the distance from the ion source in accordance with our experimental results. As an example, a calculation of the current density distribution on the spherical cap substrate was performed for a broad beam ion source operated with an anode current of 3?A. The authors propose an approach for process optimization with respect to the ion source position and its inclination, in terms of uniformity and absolute value of the ion current density.
Schrijver, Karel
United Nations Programme on Space Applications UNITED NATIONS UNITED NATIONS OFFICE FOR OUTER SPACE, Sputnik 1. Soon after that event, the Member States of the United Nations declared that space should and natural resources management. At the first United Nations Conference on the Exploration and Peaceful Uses
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Rubinstein, Robert; Kurien, Susan; Cambon, Claude
2015-06-22
The representation theory of the rotation group is applied to construct a series expansion of the correlation tensor in homogeneous anisotropic turbulence. The resolution of angular dependence is the main analytical difficulty posed by anisotropic turbulence; representation theory parametrises this dependence by a tensor analogue of the standard spherical harmonics expansion of a scalar. As a result, the series expansion is formulated in terms of explicitly constructed tensor bases with scalar coefficients determined by angular moments of the correlation tensor.
A spherically symmetric and stationary universe from a weak modification of general relativity
Christian Corda; Herman J. Mosquera Cuesta
2009-04-01
It is shown that a weak modification of general relativity, in the linearized approach, renders a spherically symmetric and stationary model of the universe. This is due to the presence of a third mode of polarization in the linearized gravity in which a "curvature" energy term is present. Such an energy can, in principle, be identified as the Dark Energy. The model can also help to a better understanding of the framework of the Einstein-Vlasov system.
Adler, Thomas A. (Corvallis, OR)
1996-01-01
The invention pertains a method of determining elastic and plastic mechanical properties of ceramics, intermetallics, metals, plastics and other hard, brittle materials which fracture prior to plastically deforming when loads are applied. Elastic and plastic mechanical properties of ceramic materials are determined using spherical indenters. The method is most useful for measuring and calculating the plastic and elastic deformation of hard, brittle materials with low values of elastic modulus to hardness.
Static spherically symmetric perfect fluid solutions in $f(R)$ theories of gravity
T. Multamaki; I. Vilja
2006-12-29
Static spherically symmetric perfect fluid solutions are studied in metric $f(R)$ theories of gravity. We show that pressure and density do not uniquely determine $f(R)$ ie. given a matter distribution and an equation state, one cannot determine the functional form of $f(R)$. However, we also show that matching the outside Schwarzschild-de Sitter-metric to the metric inside the mass distribution leads to additional constraints that severely limit the allowed fluid configurations.
Spherically symmetric analysis on open FLRW solution in non-linear massive gravity
Chiang, Chien-I; Izumi, Keisuke; Chen, Pisin E-mail: izumi@phys.ntu.edu.tw
2012-12-01
We study non-linear massive gravity in the spherically symmetric context. Our main motivation is to investigate the effect of helicity-0 mode which remains elusive after analysis of cosmological perturbation around an open Friedmann-Lemaitre-Robertson-Walker (FLRW) universe. The non-linear form of the effective energy-momentum tensor stemming from the mass term is derived for the spherically symmetric case. Only in the special case where the area of the two sphere is not deviated away from the FLRW universe, the effective energy momentum tensor becomes completely the same as that of cosmological constant. This opens a window for discriminating the non-linear massive gravity from general relativity (GR). Indeed, by further solving these spherically symmetric gravitational equations of motion in vacuum to the linear order, we obtain a solution which has an arbitrary time-dependent parameter. In GR, this parameter is a constant and corresponds to the mass of a star. Our result means that Birkhoff's theorem no longer holds in the non-linear massive gravity and suggests that energy can probably be emitted superluminously (with infinite speed) on the self-accelerating background by the helicity-0 mode, which could be a potential plague of this theory.
Spherically symmetric self-similar solutions and their astrophysical and cosmological applications
B. J. Carr
2000-03-02
We discuss spherically symmetric perfect fluid solutions of Einstein's equations which have equation of state ($p=\\alpha \\mu$) and which are self-similar in the sense that all dimensionless variables depend only upon $z\\equiv r/t$. For each value of $\\alpha$, such solutions are described by two parameters and have now been completely classified. There is a 1-parameter family of solutions asymptotic to the flat Friedmann model at large values of z. These represent either black holes or density perturbations which grow as fast as the particle horizon; the underdense solutions may be relevant to the existence of large-scale cosmic voids. There is also a 1-parameter family of solutions asymptotic to a self-similar Kantowski-Sachs model at large z. These are probably only physically realistic for $-11/5$, there is a family of solutions which are asymptotically Minkowski. These asymptote either to infinite z, in which case they are described by one parameter, or to a finite value of z, in which case they are described by two parameters and this includes the ``critical'' solution for $\\alpha >0.28$. We discuss the stability of spherically symmetric similarity solutions to more general (non-self-similar) spherically symmetric perturbations.
Linear analysis on the growth of non-spherical perturbations in supersonic accretion flows
Takahashi, Kazuya; Yamada, Shoichi, E-mail: ktakahashi@heap.phys.waseda.ac.jp [Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku 169-8555 (Japan)
2014-10-20
We analyzed the growth of non-spherical perturbations in supersonic accretion flows. We have in mind an application to the post-bounce phase of core-collapse supernovae (CCSNe). Such non-spherical perturbations have been suggested by a series of papers by Arnett, who has numerically investigated violent convections in the outer layers of pre-collapse stars. Moreover, Couch and Ott demonstrated in their numerical simulations that such perturbations may lead to a successful supernova even for a progenitor that fails to explode without fluctuations. This study investigated the linear growth of perturbations during the infall onto a stalled shock wave. The linearized equations are solved as an initial and boundary value problem with the use of a Laplace transform. The background is a Bondi accretion flow whose parameters are chosen to mimic the 15 M {sub ?} progenitor model by Woosley and Heger, which is supposed to be a typical progenitor of CCSNe. We found that the perturbations that are given at a large radius grow as they flow down to the shock radius; the density perturbations can be amplified by a factor of 30, for example. We analytically show that the growth rate is proportional to l, the index of the spherical harmonics. We also found that the perturbations oscillate in time with frequencies that are similar to those of the standing accretion shock instability. This may have an implication for shock revival in CCSNe, which will be investigated in our forthcoming paper in more detail.
The Behavior of a Spherical Hole in an Infinite Uniform Universe
Gilbert N. Lewis
1994-05-31
In this paper, the behavior of a spherical hole in an otherwise infinite and uniform universe is investigated. First, the Newtonian theory is developed. The concept of negative gravity, an outward gravitational force acting away from the center of the spherical hole, is presented, and the resulting expansion of the hole is investigated. Then, the same result is derived using the techniques of Einstein's theory of general relativity. The field equations are solved for an infinite uniform universe and then for an infinite universe in which matter is uniformly distributed except for a spherical hole. Negative pressure caused by negative gravity is utilized. The physical significance of the cosmological constant is explained, and a new physical concept, that of the gravitational potential of a hole, is discussed. The relationship between the Newtonian potential for a hole and the Schwarzschild solution of the field equations is explored. Finally, the geodesic equations are considered. It is shown that photons and particles are deflected away from the hole. An application of this idea is pursued, in which a new cosmology based upon expanding holes in a uniform universe is developed. The microwave background radiation and Hubble's Law, among others, are explained. Finally, current astronomical data are used to compute a remarkably accurate value of Hubble's constant, as well as estimates of the average mass density of the universe and the cosmological constant.
National Laboratory]; Chertkov, Michael [Los Alamos National...
Office of Scientific and Technical Information (OSTI)
Chertkov, Michael Los Alamos National Laboratory Construction and Facility Engineering; Energy Conservation, Consumption, & Utilization(32); Energy Planning, Policy, &...
Mojave National Preserve Joshua Tree National Park
Laughlin, Robert B.
Forest (SBNF) Angeles National Forest (ANF) Cleveland National Forest (CNF) CNF CNF SBNF ANF CACA 049111°0'0"N 34°0'0"N 34°0'0"N 33°0'0"N 33°0'0"N California Desert Conservation Area BLM Solar Energy Project Contingent Corridor Deleted Corridor Land Status BLM National Park Service Forest Service Military USFWS
Oak Ridge National Laboratory National Security Programs
Security Challenges #12;3 OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY How Will Our Enemies and Homeland Security #12;OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Nuclear Nonproliferation $27,050 Cleanup $7,481 Science $359M National Security $278M Energy $170M Cleanup $0.8M Total $1.08B
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Greenslade, Diana
National Environmental Information Infrastructure: Reference Architecture Contributing to the Australian Government National Plan for Environmental Information initiative #12;National Environmental Information Infrastructure: Reference Architecture v1.1 Environmental Information Programme Publication Series
Heermann, Dieter W.
A new general model with non-spherical interactions for dense polymer systems and a potential of Bisphenol-A-Poly- carbonate, which is regarded here, the torsional potential is
Bisnovatyi-Kogan, G S
2015-01-01
In this paper we review a recently developed approximate method for investigation of dynamics of compressible ellipsoidal figures. Collapse and subsequent behaviour are described by a system of ordinary differential equations for time evolution of semi-axes of a uniformly rotating, three-axis, uniform-density ellipsoid. First, we apply this approach to investigate dynamic stability of non-spherical bodies. We solve the equations that describe, in a simplified way, the Newtonian dynamics of a self-gravitating non-rotating spheroidal body. We find that, after loss of stability, a contraction to a singularity occurs only in a pure spherical collapse, and deviations from spherical symmetry prevent the contraction to the singularity through a stabilizing action of nonlinear non-spherical oscillations. The development of instability leads to the formation of a regularly or chaotically oscillating body, in which dynamical motion prevents the formation of the singularity. We find regions of chaotic and regular pulsat...
Jiang, T. F.; Tong, Xiao-Min; Chu, Shih-I
2001-01-09
We study the electronic structure and shell-filling effects of both spherical and vertical quantum dots by means of the density functional theory (DFT) with optimized effective potential (OEP) and self-interaction-correction (SIC) recently developed...
None
2010-09-01
National Science Bowl finals and awards at the National Building Museum in Washington D.C. Monday 5/3/2010
Office of Energy Efficiency and Renewable Energy (EERE)
At the Clean Energy Manufacturing Initiative's (CEMI) 2015 National Summit, stakeholders are invited to share input on national priorities for clean energy manufacturing and explore models for...
2012 National Electricity Forum
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U.S. Department of Energy U.S. Department of Energy National Electric Transmission Congestion Study Workshop - December 6, 2011 National Electric Transmission Congestion Study...
Xudong Liang; Shengqiang Cai
2015-06-12
Under the actions of internal pressure and electric voltage, a spherical dielectric elastomer balloon usually keeps a sphere during its deformation, which has also been assumed in many previous studies. In this article, using linear perturbation analysis, we demonstrate that a spherical dielectric elastomer balloon may bifurcate to a non-spherical shape under certain electromechanical loading conditions. We also show that with a non-spherical shape, the dielectric elastomer balloon may have highly inhomogeneous electric field and stress/stretch distributions, which can lead to the failure of the system. In addition, we conduct stability analysis of the dielectric elastomer balloon in different equilibrium configurations by evaluating its second variation of free energy under arbitrary perturbations. Our analyses indicate that under pressure-control and voltage-control mode, non-spherical deformation of the dielectric elastomer balloon is energetically unstable. However, under charge-control or ideal gas mass-control mode, non-spherical deformation of the balloon is energetically stable.
National Renewable Energy Laboratory
National Renewable Energy Laboratory Innovation for Our Energy Future ponsorship Format Reversed Color:White rtical Format Reversed-A ertical Format Reversed-B National Renewable Energy Laboratory National Renewable Energy Laboratory Innovation for Our Energy Future National Renewable Energy Laboratory
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Lee, Sangwoo; Leighton, Chris; Bates, Frank S.
2014-11-05
Frank–Kasper phases are tetrahedrally packed structures occurring in numerous materials, from elements to intermetallics to self-assembled soft materials. They exhibit complex manifolds of Wigner–Seitz cells with many-faceted polyhedra, forming an important bridge between the simple close-packed periodic and quasiperiodic crystals. The recent discovery of the Frank–Kasper ?-phase in diblock and tetrablock polymers stimulated the experiments reported here on a poly(isoprene-b-lactide) diblock copolymer melt. Thus, analysis of small-angle X-ray scattering and mechanical spectroscopy exposes an undiscovered competition between the tendency to form self-assembled particles with spherical symmetry, and the necessity to fill space at uniform density within the framework imposed bymore »the lattice. We thus deduce surprising analogies between the symmetry breaking at the body-centered cubic phase to ?-phase transition in diblock copolymers, mediated by exchange of mass, and the symmetry breaking in certain metals and alloys (such as the elements Mn and U), mediated by exchange of charge. Similar connections are made between the role of sphericity in real space for polymer systems, and the role of sphericity in reciprocal space for metallic systems such as intermetallic compounds and alloys. These findings establish new links between disparate materials classes, provide opportunities to improve the understanding of complex crystallization by building on synergies between hard and soft matter, and, perhaps most significantly, challenge the view that the symmetry breaking required to form reduced symmetry structures (possibly even quasiperiodic crystals) requires particles with multiple predetermined shapes and/or sizes.« less
Lee, Sangwoo; Leighton, Chris; Bates, Frank S.
2014-11-05
Frank–Kasper phases are tetrahedrally packed structures occurring in numerous materials, from elements to intermetallics to self-assembled soft materials. They exhibit complex manifolds of Wigner–Seitz cells with many-faceted polyhedra, forming an important bridge between the simple close-packed periodic and quasiperiodic crystals. The recent discovery of the Frank–Kasper ?-phase in diblock and tetrablock polymers stimulated the experiments reported here on a poly(isoprene-b-lactide) diblock copolymer melt. Thus, analysis of small-angle X-ray scattering and mechanical spectroscopy exposes an undiscovered competition between the tendency to form self-assembled particles with spherical symmetry, and the necessity to fill space at uniform density within the framework imposed by the lattice. We thus deduce surprising analogies between the symmetry breaking at the body-centered cubic phase to ?-phase transition in diblock copolymers, mediated by exchange of mass, and the symmetry breaking in certain metals and alloys (such as the elements Mn and U), mediated by exchange of charge. Similar connections are made between the role of sphericity in real space for polymer systems, and the role of sphericity in reciprocal space for metallic systems such as intermetallic compounds and alloys. These findings establish new links between disparate materials classes, provide opportunities to improve the understanding of complex crystallization by building on synergies between hard and soft matter, and, perhaps most significantly, challenge the view that the symmetry breaking required to form reduced symmetry structures (possibly even quasiperiodic crystals) requires particles with multiple predetermined shapes and/or sizes.
Dynamical Instability of Spherical Star in $f(R,T)$ gravity
Ifra Noureen; M. Zubair
2014-11-20
This work is based on stability analysis of spherically symmetric collapsing star surrounding in locally anisotropic environment in $f(R,T)$ gravity, where $R$ is Ricci scalar and $T$ corresponds to the trace of energy momentum tensor. Field equations and dynamical equations are presented in the context of $f(R,T)$ gravity. Perturbation schem is employed on dynamical equations to find the collapse equation. Furthermore, condition on adiabatic index $\\Gamma$ is constructed for Newtonian and post-Newtonian eras to address instability problem. Some constraints on physical quantities are imposed to maintain stable stellar configuration. The results in this work are in accordance with $f(R)$ gravity for specific case.
Discontinuous Galerkin method for the spherically reduced BSSN system with second-order operators
Scott E. Field; Jan S. Hesthaven; Stephen R. Lau; Abdul H. Mroue
2010-12-18
We present a high-order accurate discontinuous Galerkin method for evolving the spherically-reduced Baumgarte-Shapiro-Shibata-Nakamura (BSSN) system expressed in terms of second-order spatial operators. Our multi-domain method achieves global spectral accuracy and long-time stability on short computational domains. We discuss in detail both our scheme for the BSSN system and its implementation. After a theoretical and computational verification of the proposed scheme, we conclude with a brief discussion of issues likely to arise when one considers the full BSSN system.
On spherically symmetric metric satisfying the positive kinetic energy coordinate condition
T. Mei
2008-02-28
Generally speaking, there is a negative kinetic energy term in the Lagrangian of the Einstein-Hilbert action of general relativity; On the other hand, the negative kinetic energy term can be vanished by designating a special coordinate system. For general spherically symmetric metric, the question that seeking special coordinate system that satisfies the positive kinetic energy coordinate condition is referred to solving a linear first-order partial differential equation. And then, we present a metric corresponding to the Reissner-Nordstrom solution that satisfies the positive kinetic energy coordinate condition. Finally, we discuss simply the case of the Tolman metric.
Gusakov, E; Gusakov, Evgeniy; Surkov, Alexander
2004-01-01
The parametric instability of upper hybrid wave decay into back scattered upper hybrid wave and lower hybrid wave is considered for conditions of inhomogeneous plasma of spherical tokamaks. The possibility of absolute instability is demonstrated and the corresponding threshold is determined. It is shown that the threshold power increases with pump frequency and electron temperature. Threshold power is estimated for typical parameters of experiment in MAST tokamak. It is shown that in this case parametrical reflection arises, if probing power exceeds 129W/cm^2, which gives 40 kW for a beam of 10 cm radius.
Laser-Driven Shock Acceleration of Ion Beams from Spherical Mass-Limited Targets
Henig, A.; Kiefer, D.; Hoerlein, R.; Major, Zs.; Krausz, F.; Habs, D. [Max-Planck-Institut fuer Quantenoptik, Garching (Germany); Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Garching (Germany); Geissler, M. [Max-Planck-Institut fuer Quantenoptik, Garching (Germany); Department of Physics and Astronomy, Queen's University Belfast, Belfast BT7 1NN (United Kingdom); Rykovanov, S. G. [Max-Planck-Institut fuer Quantenoptik, Garching (Germany); Moscow Physics Engineering Institute, Kashirskoe shosse 31, Moscow (Russian Federation); Ramis, R. [ETSI Aeronauticos, Universidad Politecnica de Madrid (Spain); Osterhoff, J.; Veisz, L.; Karsch, S. [Max-Planck-Institut fuer Quantenoptik, Garching (Germany); Schreiber, J. [Max-Planck-Institut fuer Quantenoptik, Garching (Germany); Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Garching (Germany); Blackett Laboratory, Imperial College, London SW7 2AZ (United Kingdom)
2009-03-06
We report on experimental studies of ion acceleration from spherical targets of diameter 15 {mu}m irradiated by ultraintense (1x10{sup 20} W/cm{sup 2}) pulses from a 20-TW Ti:sapphire laser system. A highly directed proton beam with plateau-shaped spectrum extending to energies up to 8 MeV is observed in the laser propagation direction. This beam arises from acceleration in a converging shock launched by the laser, which is confirmed by 3-dimensional particle-in-cell simulations. The temporal evolution of the shock-front curvature shows excellent agreement with a two-dimensional radiation pressure model.
Unconstrained hyperboloidal evolution of black holes in spherical symmetry with GBSSN and Z4c
Alex Vañó-Viñuales; Sascha Husa
2014-12-15
We consider unconstrained evolution schemes for the hyperboloidal initial value problem in numerical relativity as a promising candidate for the optimally efficient numerical treatment of radiating compact objects. Here, spherical symmetry already poses nontrivial problems and constitutes an important first step to regularize the resulting singular PDEs. We evolve the Einstein equations in their generalized BSSN and Z4 formulations coupled to a massless self-gravitating scalar field. Stable numerical evolutions are achieved for black hole initial data, and critically rely on the construction of appropriate gauge conditions.
A detailed study of collisionless explosion of single- and two-ion-species spherical nanoplasmas
Popov, K. I. [Theoretical Physics Institute, University of Alberta, Edmonton, Alberta T6G 2J1 (Canada); Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5 (Canada); Bychenkov, V. Yu. [Theoretical Physics Institute, University of Alberta, Edmonton, Alberta T6G 2J1 (Canada); P. N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow 119991 (Russian Federation); Rozmus, W. [Theoretical Physics Institute, University of Alberta, Edmonton, Alberta T6G 2J1 (Canada); Ramunno, L. [Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5 (Canada)
2010-08-15
The collisionless adiabatic expansion into vacuum of spherical plasma targets (clusters) composed of cold single- or multispecies ions and hot electrons is studied kinetically by numerical solving of the nonrelativistic equations of motion of plasma particles in the self-consistent electrostatic field. The expansion dynamics for the whole range of electron temperatures from much less than to much higher than the cluster Coulomb energy is described for various initial plasma density profiles and cluster structures. The explosion of two ion species heterogeneous (layered) and homogeneously mixed targets is studied in detail for the wide range of light ion concentration and kinematic parameter.
ABAREX -- A neutron spherical optical-statistical-model code -- A user`s manual
Smith, A.B. [ed.; Lawson, R.D.
1998-06-01
The contemporary version of the neutron spherical optical-statistical-model code ABAREX is summarized with the objective of providing detailed operational guidance for the user. The physical concepts involved are very briefly outlined. The code is described in some detail and a number of explicit examples are given. With this document one should very quickly become fluent with the use of ABAREX. While the code has operated on a number of computing systems, this version is specifically tailored for the VAX/VMS work station and/or the IBM-compatible personal computer.
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Two-fluid simulations of driven reconnection in the Mega-Ampere Spherical Tokamak
Stanier, A; Gordovskyy, M; McClements, K G; Gryaznevich, M P; Lukin, V S
2013-01-01
In the merging-compression method of plasma start-up, two flux-ropes with parallel toroidal current are formed around in-vessel poloidal field coils, before merging to form a spherical tokamak plasma. This start-up method, used in the Mega-Ampere Spherical Tokamak (MAST), is studied as a high Lundquist number and low plasma-beta magnetic reconnection experiment. In this paper, 2D fluid simulations are presented of this merging process in order to understand the underlying physics, and better interpret the experimental data. These simulations examine the individual and combined effects of tight-aspect ratio geometry and two-fluid physics on the merging. The ideal self-driven flux-rope dynamics are coupled to the diffusion layer physics, resulting in a large range of phenomena. For resistive MHD simulations, the flux-ropes enter the sloshing regime for normalised resistivity eta < 1E-5. In Hall-MHD three regimes are found for the qualitative behaviour of the current sheet, depending on the ratio of the curre...
New model of calculating the energy transfer efficiency for the spherical theta-pinch device
Xu, G; Loisch, G; Xiao, G; Jacoby, J; Weyrich, K; Li, Y; Zhao, Y
2015-01-01
Ion-beam-plasma-interaction plays an important role in the field of Warm Dense Matter (WDM) and Inertial Confinement Fusion (ICF). A spherical theta pinch is proposed to act as a plasma target in various applications including a plasma stripper cell. One key parameter for such applications is the free electron density. A linear dependency of this density to the amount of energy transferred into the plasma from an energy storage was found by C. Teske. Since the amount of stored energy is known, the energy transfer efficiency is a reliable parameter for the design of a spherical theta pinch device. The traditional two models of energy transfer efficiency are based on assumptions which comprise the risk of systematical errors. To obtain precise results, this paper proposes a new model without the necessity of any assumption to calculate the energy transfer efficiency for an inductively coupled plasma device. Further, a comparison of these three different models is given at a fixed operation voltage for the full ...
Spherical collapse in Galileon gravity: fifth force solutions, halo mass function and halo bias
Barreira, Alexandre; Li, Baojiu; Baugh, Carlton M.; Pascoli, Silvia E-mail: liqb@mail.ihep.ac.cn E-mail: silvia.pascoli@durham.ac.uk
2013-11-01
We study spherical collapse in the Quartic and Quintic Covariant Galileon gravity models within the framework of the excursion set formalism. We derive the nonlinear spherically symmetric equations in the quasi-static and weak-field limits, focusing on model parameters that fit current CMB, SNIa and BAO data. We demonstrate that the equations of the Quintic model do not admit physical solutions of the fifth force in high density regions, which prevents the study of structure formation in this model. For the Quartic model, we show that the effective gravitational strength deviates from the standard value at late times (z?<1), becoming larger if the density is low, but smaller if the density is high. This shows that the Vainshtein mechanism at high densities is not enough to screen all of the modifications of gravity. This makes halos that collapse at z?<1 feel an overall weaker gravity, which suppresses halo formation. However, the matter density in the Quartic model is higher than in standard ?CDM, which boosts structure formation and dominates over the effect of the weaker gravity. In the Quartic model there is a significant overabundance of high-mass halos relative to ?CDM. Dark matter halos are also less biased than in ?CDM, with the difference increasing appreciably with halo mass. However, our results suggest that the bias may not be small enough to fully reconcile the predicted matter power spectrum with LRG clustering data.
Nonlinear effects in the extraction of laminar flame speeds from expanding spherical flames
Kelley, A.P.; Law, C.K.
2009-09-15
Various factors affecting the determination of laminar flames speeds from outwardly propagating spherical flames in a constant-pressure combustion chamber were considered, with emphasis on the nonlinear variation of the stretched flame speed to the flame stretch rate, and the associated need to nonlinearly extrapolate the stretched flame speed to yield an accurate determination of the laminar flame speed and Markstein length. Experiments were conducted for lean and rich n-butane/air flames at 1atm initial pressure, demonstrating the complex and nonlinear nature of the dynamics of flame evolution, and the strong influences of the ignition transient and chamber confinement during the initial and final periods of the flame propagation, respectively. These experimental data were analyzed using the nonlinear relation between the stretched flame speed and stretch rate, yielding laminar flame speeds that agree well with data determined from alternate flame configurations. It is further suggested that the fidelity in the extraction of the laminar flame speed from expanding spherical flames can be facilitated by using small ignition energy and a large combustion chamber. (author)
Fate of Accidental Symmetries of the Relativistic Hydrogen Atom in a Spherical Cavity
M. H. Al-Hashimi; A. M. Shalaby; U. -J. Wiese
2015-04-16
The non-relativistic hydrogen atom enjoys an accidental $SO(4)$ symmetry, that enlarges the rotational $SO(3)$ symmetry, by extending the angular momentum algebra with the Runge-Lenz vector. In the relativistic hydrogen atom the accidental symmetry is partially lifted. Due to the Johnson-Lippmann operator, which commutes with the Dirac Hamiltonian, some degeneracy remains. When the non-relativistic hydrogen atom is put in a spherical cavity of radius $R$ with perfectly reflecting Robin boundary conditions, characterized by a self-adjoint extension parameter $\\gamma$, in general the accidental $SO(4)$ symmetry is lifted. However, for $R = (l+1)(l+2) a$ (where $a$ is the Bohr radius and $l$ is the orbital angular momentum) some degeneracy remains when $\\gamma = \\infty$ or $\\gamma = \\frac{2}{R}$. In the relativistic case, we consider the most general spherically and parity invariant boundary condition, which is characterized by a self-adjoint extension parameter. In this case, the remnant accidental symmetry is always lifted in a finite volume. We also investigate the accidental symmetry in the context of the Pauli equation, which sheds light on the proper non-relativistic treatment including spin. In that case, again some degeneracy remains for specific values of $R$ and $\\gamma$.
Non-perturbative corrections to mean-field behavior: spherical model on spider-web graph
Ajit C. Balram; Deepak Dhar
2012-02-09
We consider the spherical model on a spider-web graph. This graph is effectively infinite-dimensional, similar to the Bethe lattice, but has loops. We show that these lead to non-trivial corrections to the simple mean-field behavior. We first determine all normal modes of the coupled springs problem on this graph, using its large symmetry group. In the thermodynamic limit, the spectrum is a set of $\\delta$-functions, and all the modes are localized. The fractional number of modes with frequency less than $\\omega$ varies as $\\exp (-C/\\omega)$ for $\\omega$ tending to zero, where $C$ is a constant. For an unbiased random walk on the vertices of this graph, this implies that the probability of return to the origin at time $t$ varies as $\\exp(- C' t^{1/3})$, for large $t$, where $C'$ is a constant. For the spherical model, we show that while the critical exponents take the values expected from the mean-field theory, the free-energy per site at temperature $T$, near and above the critical temperature $T_c$, also has an essential singularity of the type $\\exp[ -K {(T - T_c)}^{-1/2}]$.
Thierry Daude; Damien Gobin; François Nicoleau
2015-01-15
In this paper, we adapt the well-known \\emph{local} uniqueness results of Borg-Marchenko type in the inverse problems for one dimensional Schr{\\"o}dinger equation to prove \\emph{local} uniqueness results in the setting of inverse \\emph{metric} problems. More specifically, we consider a class of spherically symmetric manifolds having two asymptotically hyperbolic ends and study the scattering properties of massless Dirac waves evolving on such manifolds. Using the spherical symmetry of the model, the stationary scattering is encoded by a countable family of one-dimensional Dirac equations. This allows us to define the corresponding transmission coefficients $T(\\lambda,n)$ and reflection coefficients $L(\\lambda,n)$ and $R(\\lambda,n)$ of a Dirac wave having a fixed energy $\\lambda$ and angular momentum $n$. For instance, the reflection coefficients $L(\\lambda,n)$ correspond to the scattering experiment in which a wave is sent from the \\emph{left} end in the remote past and measured in the same left end in the future. The main result of this paper is an inverse uniqueness result local in nature. Namely, we prove that for a fixed $\\lambda \
Quantum superposition principle and gravitational collapse: Scattering times for spherical shells
Ambrus, M.; Hajicek, P.
2005-09-15
A quantum theory of spherically symmetric thin shells of null dust and their gravitational field is studied. In Nucl. Phys. B603, 555 (2001), it has been shown how superpositions of quantum states with different geometries can lead to a solution of the singularity problem and black hole information paradox: the shells bounce and re-expand and the evolution is unitary. The corresponding scattering times will be defined in the present paper. To this aim, a spherical mirror of radius R{sub m} is introduced. The classical formula for scattering times of the shell reflected from the mirror is extended to quantum theory. The scattering times and their spreads are calculated. They have a regular limit for R{sub m}{yields}0 and they reveal a resonance at E{sub m}=c{sup 4}R{sub m}/2G. Except for the resonance, they are roughly of the order of the time the light needs to cross the flat space distance between the observer and the mirror. Some ideas are discussed of how the construction of the quantum theory could be changed so that the scattering times become considerably longer.
NSTX-U Digital Coil Protection System Software Detailed Design
2014-06-01
The National Spherical Torus Experiment (NSTX) currently uses a collection of analog signal processing solutions for coil protection. Part of the NSTX Upgrade (NSTX-U) entails replacing these analog systems with a software solution running on a conventional computing platform. The new Digital Coil Protection System (DCPS) will replace the old systems entirely, while also providing an extensible framework that allows adding new functionality as desired.
Electromagnetic Transport From Microtearing Mode Turbulence
Guttenfelder, W; Kaye, S M; Nevins, W M; Wang, E; Bell, R E; Hammett, G W; LeBlanc, B P; Mikkelsen, D R
2011-03-23
This Letter presents non-linear gyrokinetic simulations of microtearing mode turbulence. The simulations include collisional and electromagnetic effects and use experimental parameters from a high beta discharge in the National Spherical Torus Experiment (NSTX). The predicted electron thermal transport is comparable to that given by experimental analysis, and it is dominated by the electromagnetic contribution of electrons free streaming along the resulting stochastic magnetic field line trajectories. Experimental values of flow shear can significantly reduce the predicted transport.
(NSTX) D.A. Gates, R. Maingi, J. Menard, S. Kaye, S.A. Sabbagh, G. Taylor, J.R. Wilson, et al. November2 , G. Taylor1 , J.R. Wilson1 , M.G. Bell1 , R.E. Bell1 , S. Bernabei1 , J. Bialek2 , T. Biewer1 , W in the National Spherical Torus Experiment (NSTX) D. A. Gates1 , R. Maingi4 , J. Menard1 , S. Kaye1 , S.A. Sabbagh
Hu, Michael Z.
2006-05-23
Disclosed is a method for making amorphous spherical particles of zirconium titanate and crystalline spherical particles of zirconium titanate comprising the steps of mixing an aqueous solution of zirconium salt and an aqueous solution of titanium salt into a mixed solution having equal moles of zirconium and titanium and having a total salt concentration in the range from 0.01 M to about 0.5 M. A stearic dispersant and an organic solvent is added to the mixed salt solution, subjecting the zirconium salt and the titanium salt in the mixed solution to a coprecipitation reaction forming a solution containing amorphous spherical particles of zirconium titanate wherein the volume ratio of the organic solvent to aqueous part is in the range from 1 to 5. The solution of amorphous spherical particles is incubated in an oven at a temperature .ltoreq.100.degree. C. for a period of time .ltoreq.24 hours converting the amorphous particles to fine or ultrafine crystalline spherical particles of zirconium titanate.
National Energy Education Summit
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The National Energy Education Summit is organized by the Council of Energy Research and Education Leaders (CEREL) and will serve as a first-of-its-kind national forum for energy educators, subject...
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National Environmental Research Parks
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1994-07-01
The National Environmental Research Parks are outdoor laboratories that provide opportunities for environmental studies on protected lands that act as buffers around Department of Energy (DOE) facilities. The research parks are used to evaluate the environmental consequences of energy use and development as well as the strategies to mitigate these effects. They are also used to demonstrate possible environmental and land-use options. The seven parks are: Fermilab National Environmental Research Park; Hanford National Environmental Research Park; Idaho National Environmental Research Park; Los Alamos National Environmental Research Park; Nevada National Environmental Research Park; Oak Ridge National Environmental Research Park; and Savannah River National Environmental Research Park. This document gives an overview of the events that led to the creation of the research parks. Its main purpose is to summarize key points about each park, including ecological research, geological characteristics, facilities, and available databases.
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Laser induced thermal-wave fields in multi-layered spherical solids based on Green function method
Zhang Jie; Wang Chinhua [Key Lab of Modern Optical Technologies of Jiangsu Province, Institute of Modern Optical Technologies, Soochow University, Suzhou, Jiangsu 215006 (China); Xie Guangxi [Key Lab of Modern Optical Technologies of Jiangsu Province, Institute of Modern Optical Technologies, Soochow University, Suzhou, Jiangsu 215006 (China); Department of Physics, Jiangnan University, Wuxi, Jiangsu 214122 (China); Mandelis, Andreas [Center for Advanced Diffusion-Wave Technologies (CADIFT), Department of Mechanical and Industrial Engineering, University of Toronto, M5S 3G8 Ontario (Canada)
2012-08-01
In this paper, we establish a Green-function based theoretical model for evaluating solid multi-layered spherical samples which are illuminated by a frequency modulated incident beam. The specific Green function for the multi-layered spherical structure is derived and an analytical expression for the thermal-wave field in such a spherical sample is presented. The characteristics of the thermal-wave field with respect to the thermophysical, geometrical, and measurement parameters are presented. Unlike the quadruple method, the Green function method is capable of evaluating thermal-wave fields at any point of multi-layered structures with arbitrary intensity distributions of incident laser beams. Furthermore, experimental validation is also presented in the form of experimental results with steel spheres of various diameters.
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Climate Change and National Security
Alyson, Fleming; Summer, Kelly; Summer, Martin; Lauren, Franck; Jonathan, Mark
2015-01-01
for Environment and National Security Scripps Institution ofMultiplying Threats to National Security Higher temperaturesefforts to protect national security. Page 2 The U.S. Armed
Review: Manufacturing National Park Nature
Mason, Fred
2012-01-01
Review: Manufacturing National Park Nature: Photography,Canada Cronin, J. Keri. Manufacturing National Park Nature:J. Keri Cronin’s book Manufacturing National Park Nature
Che, S.; Sakurai, O.; Funakubo, H.; Shinozaki, K.; Mizutani, N. [Department of Inorganic Materials, Faculty of Engineering, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152 (Japan)
1997-02-01
Ca-modified spherical palladium particles were prepared from the mixed solution of Pd(NO{sub 3}){sub 2} and Ca(NO{sub 3}){sub 2} by ultrasonic spray pyrolysis. Pure palladium powder and that modified with less than 55 ppm Ca were composed of single crystal particles. However, Ca addition of more than 550 ppm resulted in polycrystalline particles. Crystallite size of the particles decreased with the increase of Ca addition and changed dramatically at the addition of some hundred ppm. Ca additive did not form solid solution with palladium but formed CaPd{sub 3}O{sub 4} on the surface and grain boundary of the particles. 50 ppm{endash}1{percent} of Ca addition significantly reduced the oxidization of palladium powder. More addition of Ca resulted in excess oxidation due to the reaction between palladium and calcium oxide. {copyright} {ital 1997 Materials Research Society.}
Kawakami, Hayato; Mitsuda, Eiji; Nambu, Yasusada; Tomimatsu, Akira
2009-07-15
In considering the gravitational collapse of matter, it is an important problem to clarify what kind of conditions leads to the formation of naked singularity. For this purpose, we apply the 1+3 orthonormal frame formalism introduced by Uggla et al. to the spherically symmetric gravitational collapse of a perfect fluid. This formalism allows us to construct an autonomous system of evolution and constraint equations for scale-invariant dynamical variables normalized by the volume expansion rate of the timelike orthonormal frame vector. We investigate the asymptotic evolution of such dynamical variables towards the formation of a central singularity and present a conjecture that the steep spatial gradient for the normalized density function is a characteristic of the naked singularity formation.
Naked singularity formation in the collapse of a spherical cloud of counterrotating particles
Tomohiro Harada; Hideo Iguchi; Ken-ichi Nakao
1998-07-09
We investigate collapse of a spherical cloud of counter-rotating particles. An explicit solution is given using an elliptic integral. If the specific angular momentum $L(r)=O(r^2)$ at $r\\to 0$, no central singularity occurs. With $L(r)$ like that, there is a finite region around the center that bounces. On the other hand, if the order of $L(r)$ is higher than that, a central singularity occurs. In marginally bound collapse with $L(r)=4F(r)$, a naked singularity occurs, where $F(r)$ is the Misner-Sharp mass. The solution for this case is expressed by elementary functions. For $ 4 naked singularity occurs. For $ 0 \\le L/F< 4$ at $r\\to0$, there is no such region. The results suggests that rotation may play a crucial role on the final fate of collapse.
Some comments on the nature of initial data in spherical collapse
T. P. Singh
1997-02-12
Various authors have shown the occurence of naked singularities and black holes in the spherical gravitational collapse of inhomogeneous dust. In a recent preprint, Antia has criticised a statement in a paper by Jhingan, Joshi and Singh on dust collapse. We show that his criticism is invalid. Antia shows that in Eulerian coordinates a series expansion for the density of a collapsing Newtonian fluid can have only even powers. However, he has overlooked the fact that Jhingan et al. have actually used Lagrangian (comoving) coordinates, and not Eulerian coordinates. As we show, in Lagrangian coordinates there is no restriction that the density have only even powers and hence his criticism is invalid. We also point out that an earlier claim by Antia on the instability of strong naked singularities in dust collapse is not supported by any concrete analysis, and is hence incorrect.
Critical radius for sustained propagation of spark-ignited spherical flames
Kelley, Andrew P.; Jomaas, Grunde; Law, Chung K.
2009-05-15
An experimental study was performed to determine the requirements for sustained propagation of spark-ignited hydrogen-air and butane-air flames at atmospheric and elevated pressures. Results show that sustained propagation is always possible for mixtures whose Lewis number is less than unity, as long as a flame can be initially established. However, for mixtures whose Lewis number is greater than unity, sustained propagation depends on whether the initially ignited flame can attain a minimum radius. This minimum radius was determined for mixtures of different equivalence ratios and pressures, and was found to agree moderately well with the theoretically predicted critical radius beyond which there is no solution for the adiabatic, quasi-steady propagation of the spherical flame. The essential roles of pressure, detailed chemistry, and the need to use local values in the quantitative evaluation of the flame response parameters are emphasized. (author)
Measurements of the divergence of fast electrons in laser-irradiated spherical targets
Yaakobi, B.; Solodov, A. A.; Myatt, J. F.; Delettrez, J. A.; Stoeckl, C.; Froula, D. H.
2013-09-15
In recent experiments using directly driven spherical targets on the OMEGA laser system, the energy in fast electrons was found to reach ?1% of the laser energy at an irradiance of ?1.1 × 10{sup 15} W/cm{sup 2}. The fraction of these fast electrons absorbed in the compressed fuel shell depends on their angular divergence. This paper describes measurements of this divergence deduced from a series of shots where Mo-coated shells of increasing diameter (D) were suspended within an outer CH shell. The intensity of the Mo–K? line and the hard x-ray radiation were found to increase approximately as ?D{sup 2}, indicating wide divergence of the fast electrons. Alternative interpretations of these results (electron scattering, radiation excitation of K?, and an electric field due to return current) are shown to be unimportant.
The influence of dynamical friction on the collapse of spherical density pertubation
A. Del Popolo; M. Gambera; V. Antonuccio-Delogu
1996-10-24
We solve numerically the equations of motion for the collapse of a shell of baryonic matter falling into the central regions of a cluster of galaxies, taking into account of the presence of the substructure inducing dynamical friction. The evolution of the expansion parameter a(t) of the perturbation is calculated in spherical systems. The effect of dynamical friction is to reduce the binding radius and the total mass accreted by the central regions. Using a peak density profile given by Bardeen et al. (1986) we show how the binding radius of the perturbation is modified by dinamical friction. We show how dynamical friction modifies the collapse parameter of the perturbation slowing down the collapse.
Calculation of the fast ion tail distribution for a spherically symmetric hot spot
McDevitt, C. J.; Tang, X.-Z.; Guo, Z.; Berk, H. L.
2014-10-15
The fast ion tail for a spherically symmetric hot spot is computed via the solution of a simplified Fokker-Planck collision operator. Emphasis is placed on describing the energy scaling of the fast ion distribution function in the hot spot as well as the surrounding cold plasma throughout a broad range of collisionalities and temperatures. It is found that while the fast ion tail inside the hot spot is significantly depleted, leading to a reduction of the fusion yield in this region, a surplus of fast ions is observed in the neighboring cold plasma region. The presence of this surplus of fast ions in the neighboring cold region is shown to result in a partial recovery of the fusion yield lost in the hot spot.
Onsager's irreversible thermodynamics of the dynamics of transient pores in spherical lipid vesicles
L. Martínez-Balbuena; E. Hernández-Zapata; I. Santamaría-Holek
2015-06-09
Onsager's irreversible thermodynamics is used to perform a systematic deduction of the kinetic equations governing the opening and collapse of transient pores in spherical vesicles. We show that the edge tension has to be determined from the initial stage of the pore relaxation and that in the final state the vesicle membrane is not completely relaxed, since the surface tension and the pressure difference are about $25\\%$ of its initial value. We also show that the pore life-time is controlled by the solution viscosity and its opening is driven by the solution leak-out and the surface tension drop. The final collapse is due to a non-linear interplay between the edge and the surface tensions together with the pressure difference. Also, we discuss the connection with previous models.
Miguel Alcubierre; Jose M. Torres
2014-11-06
We introduce a set of constraint preserving boundary conditions for the Baumgarte-Shapiro-Shibata-Nakamura (BSSN) formulation of the Einstein evolution equations in spherical symmetry, based on its hyperbolic structure. While the outgoing eigenfields are left to propagate freely off the numerical grid, boundary conditions are set to enforce that the incoming eigenfields don't introduce spurious reflections and, more importantly, that there are no fields introduced at the boundary that violate the constraint equations. In order to do this we adopt two different approaches to set boundary conditions for the extrinsic curvature, by expressing either the radial or the time derivative of its associated outgoing eigenfield in terms of the constraints. We find that these boundary conditions are very robust in practice, allowing us to perform long lasting evolutions that remain accurate and stable, and that converge to a solution that satisfies the constraints all the way to the boundary.
A. V. Getling; R. D. Simitev; F. H. Busse
2006-10-25
A convection-driven MHD dynamo in a rotating spherical shell, with clearly defined structural elements in the flow and magnetic field, is simulated numerically. Such dynamos can be called deterministic, in contrast to those explicitly dependent on the assumed properties of turbulence. The cases most interesting from the standpoint of studying the nature of stellar magnetism demonstrate the following features. On a global scale, the convective flows can maintain a ``general'' magnetic field with a sign-alternating dipolar component. Local (in many cases, bipolar) magnetic structures are associated with convection cells. Disintegrating local structures change into background fields, which drift toward the poles. From time to time, reversals of the magnetic fields in the polar regions occur, as ``new'' background fields expel the ``old'' fields.
Perihelion precession and deflection of light in the general spherically symmetric spacetime
Ya-Peng Hu; Hongsheng Zhang; Jun-Peng Hou; Liang-Zun Tang
2014-11-27
In this paper, the perihelion precession and deflection of light have been investigated in the 4-dimensional general spherically symmetric spacetime, and the main equation is obtained. As the application of this main equation, the Reissner-Nordstorm-AdS solution and Clifton-Barrow solution in $f(R)$ gravity have been taken for the examples. We find that both the electric charge and $f(R)$ gravity can affect the perihelion precession and deflection of light, while the cosmological constant can only effect the perihelion precession. Moreover, we clarify a subtlety in the deflection of light in the solar system that the possible sun's electric charge is usually used to interpret the gap between the experiment data and theoretical result. However, after also considering the effect from the sun's same electric charge on the perihelion precession of Mercury, we can find that it is not the truth.
Quasi-spherical direct drive fusion simulations for the Z machine and future accelerators.
VanDevender, J. Pace; McDaniel, Dillon Heirman; Roderick, Norman Frederick; Nash, Thomas J.
2007-11-01
We explored the potential of Quasi-Spherical Direct Drive (QSDD) to reduce the cost and risk of a future fusion driver for Inertial Confinement Fusion (ICF) and to produce megajoule thermonuclear yield on the renovated Z Machine with a pulse shortening Magnetically Insulated Current Amplifier (MICA). Analytic relationships for constant implosion velocity and constant pusher stability have been derived and show that the required current scales as the implosion time. Therefore, a MICA is necessary to drive QSDD capsules with hot-spot ignition on Z. We have optimized the LASNEX parameters for QSDD with realistic walls and mitigated many of the risks. Although the mix-degraded 1D yield is computed to be {approx}30 MJ on Z, unmitigated wall expansion under the > 100 gigabar pressure just before burn prevents ignition in the 2D simulations. A squeezer system of adjacent implosions may mitigate the wall expansion and permit the plasma to burn.
Minimizers of the Landau-de Gennes energy around a spherical colloid particle
Stan Alama; Lia Bronsard; Xavier Lamy
2015-05-04
We consider energy minimizing configurations of a nematic liquid crystal around a spherical colloid particle, in the context of the Landau-de Gennes model. The nematic is assumed to occupy the exterior of a ball of radius r_0, satisfy homeotropic weak anchoring at the surface of the colloid, and approach a uniform uniaxial state at infinity. We study the minimizers in two different limiting regimes: for balls which are small compared to the characteristic length scale r_0>L. The relationship between the radius and the anchoring strength W is also relevant. For small balls we obtain a limiting quadrupolar configuration, with a "Saturn ring" defect for relatively strong anchoring, corresponding to an exchange of eigenvalues of the Q-tensor. In the limit of very large balls we obtain an axisymmetric minimizer of the Oseen-Frank energy, and a dipole configuration with exactly one point defect is obtained.
Microscopic description of spherical to {gamma}-soft shape transitions in Ba and Xe nuclei
Li, Z. P.; Niksic, T.; Vretenar, D.; Meng, J.
2010-03-15
The rapid transition between spherical and {gamma}-soft shapes in Ba and Xe nuclei in the mass region A>=130 is analyzed using excitation spectra and collective wave functions obtained by diagonalization of a five-dimensional Hamiltonian for quadrupole vibrational and rotational degrees of freedom, with parameters determined by constrained self-consistent relativistic mean-field calculations for triaxial shapes. The results reproduce the characteristic evolution of excitation spectra and E2 transition probabilities, and in general, a good agreement with available data is obtained. The calculated spectra display fingerprints of a second-order shape phase transition that can approximately be described by analytic solutions corresponding to the E(5) dynamical symmetry.
Generation of spherically symmetric metrics in $f\\left( R\\right) $ gravity
Z. Amirabi; M. Halilsoy; S. Habib Mazharimousavi
2015-09-29
In $D-$dimensional spherically symmetric $f\\left( R\\right) $ gravity there are three unknown functions to be determined from the fourth order differential equations. It is shown that the system remarkably integrates to relate two functions through the third one to provide reduction to second order equations accompanied with a large class of potential solutions. The third function which acts as the generator of the process is $F\\left( R\\right) =\\frac{df\\left( R\\right) }{dR}.$ As particular examples, besides known ones, we obtain new black hole solutions in any dimension $D$. We further extend our analysis to cover particularly chosen non-zero energy-momentum tensors.
Generation of spherically symmetric metrics in $f\\left( R\\right) $ gravity
Amirabi, Z; Mazharimousavi, S Habib
2015-01-01
In $D-$dimensional spherically symmetric $f\\left( R\\right) $ gravity there are three unknown functions to be determined from the fourth order differential equations. It is shown that the system remarkably integrates to relate two functions through the third one to provide reduction to second order equations accompanied with a large class of potential solutions. The third function which acts as the generator of the process is $F\\left( R\\right) =\\frac{df\\left( R\\right) }{dR}.$ As particular examples, besides known ones, we obtain new black hole solutions in any dimension $D$. We further extend our analysis to cover particularly chosen non-zero energy-momentum tensors.
Effects of ghost dark energy perturbations on the evolution of spherical overdensities
Malekjani, Mohammad; Pace, Francesco
2015-01-01
While in the standard cosmological model the accelerated expansion of the Universe is explained by invoking the presence of the cosmological constant term, it is still unclear the true origin of this stunning observational fact. It is therefore interesting to explore alternatives to the simplest scenario, in particular by assuming a more general framework where the fluid responsible of the accelerated expansion is characterised by a time-dependant equation of state. Usually these models, dubbed dark energy models, are purely phenomenological, but in this work we concentrate on a theoretically justified model, the ghost dark energy model. Within the framework of the spherical collapse model, we evaluate effects of dark energy perturbations both at the linear and non-linear level and transfer these results into an observable quantity, the mass function, by speculatively taking into account contributions of dark energy to the mass of the halos. We showed that the growth rate is higher in ghost models and that pe...
T. Wiegelmann; T. Neukirch; P. Ruan; B. Inhester
2008-01-18
Context: This paper presents a method which can be used to calculate models of the global solar corona from observational data. Aims: We present an optimization method for computing nonlinear magnetohydrostatic equilibria in spherical geometry with the aim to obtain self-consistent solutions for the coronal magnetic field, the coronal plasma density and plasma pressure using observational data as input. Methods: Our code for the self-consistent computation of the coronal magnetic fields and the coronal plasma solves the non-force-free magnetohydrostatic equilibria using an optimization method. Previous versions of the code have been used to compute non-linear force-free coronal magnetic fields from photospheric measurements in Cartesian and spherical geometry, and magnetostatic-equilibria in Cartesian geometry. We test our code with the help of a known analytic 3D equilibrium solution of the magnetohydrostatic equations. The detailed comparison between the numerical calculations and the exact equilibrium solutions is made by using magnetic field line plots, plots of density and pressure and some of the usual quantitative numerical comparison measures. Results: We find that the method reconstructs the equilibrium accurately, with residual forces of the order of the discretisation error of the analytic solution. The correlation with the reference solution is better than 99.9% and the magnetic energy is computed accurately with an error of <0.1%. Conclusions: We applied the method so far to an analytic test case. We are planning to use this method with real observational data as input as soon as possible.
The importance of electrothermal terms in Ohm's law for magnetized spherical implosions
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Davies, J. R.; Betti, R.; Chang, P. -Y.; Fiksel, G.
2015-11-06
The magnetohydrodynamics (MHD) of magnetic-field compression in laser-driven spherical targets is considered. Magnetic-field evolution is cast in terms of an effective fluid velocity, a convective term resulting from resistivity gradients, a resistive diffusion term, and a source term. Effective velocity is the sum of fluid velocity, drift velocity, and heat-flux velocity, given by electron heat flux divided by electron enthalpy density, which has two components: the perpendicular or Nernst velocity and the cross-field velocity. The Nernst velocity compresses the magnetic field as a heat front moves into the gas. The cross-field velocity leads to dynamo generation of an azimuthal magneticmore »field. It is proposed that the heat-flux velocity should be flux limited using a “Nernst” flux limiter independent of the thermal flux limiter but should not exceed it. The addition of MHD routines to the 1-D, Lagrangian hydrocode LILAC and the Eulerian version of the 2-D hydrocode DRACO is described, and the codes are used to model a magnetized spherical compression on the OMEGA laser. Thermal flux limiting at a shock front is found to cause unphysical electron temperature gradients that lead to large, unphysical magnetic fields caused by the resistivity gradient, so thermal flux limiting in the gas is removed. The Nernst term reduces the benefits of magnetization in inertial fusion. In addition, a Nernst flux limiter ? 0.12 is required in the gas in order to agree with measured neutron yield and increases in the neutron-averaged ion temperature caused by magnetization. This corresponds to maintaining the Nernst velocity below the shock velocity, which prevents significant decoupling of the magnetic field and gas compression.« less
Cerveny, Vlastislav
processes PHYSICAL MODEL a pre-stressed self-gravitating spherical Earth Maxwell viscoelastic rheology arbitrary parameter stratification both compressible and incompressible models cyclic loading and unloading [4,5] numerically stiff initial value problem inversion of sparse (block diagonal) matrices OUTPUT
for and determining the attractiveness of the compact stellarator as the basis for a fusion power reactor. However and current-drive techniques. This may result in smaller, more powerful fusion reactors. In a statement5/28/08 6:03 PMPrinceton University - PPPL to phase out compact stellarator experiment, upgrade
Prager, Stewart; Zwicker, Andrew; Hammet, Greg; Tresemer, Kelsey; Diallo, Ahmed
2014-06-06
At the Energy Department's Princeton Plasma Physics Lab, scientists are trying to accomplish what was once considered the realm of science fiction: create a star on Earth. The National Spherical Torus Experiment (NSTX) is a magnetic fusion device that is used to study the physics principles of spherically shaped plasmas -- hot ionized gases in which, under the right conditions, nuclear fusion will occur. Fusion is the energy source of the sun and all of the stars. Not just limited to theoretical work, the NSTX is enabling cutting-edge research to develop fusion as a future energy source.
Prager, Stewart; Zwicker, Andrew; Hammet, Greg; Tresemer, Kelsey; Diallo, Ahmed
2014-03-05
At the Energy Department's Princeton Plasma Physics Lab, scientists are trying to accomplish what was once considered the realm of science fiction: create a star on Earth. The National Spherical Torus Experiment (NSTX) is a magnetic fusion device that is used to study the physics principles of spherically shaped plasmas -- hot ionized gases in which, under the right conditions, nuclear fusion will occur. Fusion is the energy source of the sun and all of the stars. Not just limited to theoretical work, the NSTX is enabling cutting-edge research to develop fusion as a future energy source.
Chen, Zheng [State Key Laboratory for Turbulence and Complex Systems, Department of Mechanics and Aerospace Engineering, College of Engineering, Peking University, Beijing 100871 (China)
2010-12-15
Large discrepancies between the laminar flame speeds and Markstein lengths measured in experiments and those predicted by simulations for ultra-lean methane/air mixtures bring a great concern for kinetic mechanism validation. In order to quantitatively explain these discrepancies, a computational study is performed for propagating spherical flames of lean methane/air mixtures in different spherical chambers using different radiation models. The emphasis is focused on the effects of radiation and compression. It is found that the spherical flame propagation speed is greatly reduced by the coupling between thermal effect (change of flame temperature or unburned gas temperature) and flow effect (inward flow of burned gas) induced by radiation and/or compression. As a result, for methane/air mixtures near the lean flammability limit, the radiation and compression cause large amounts of under-prediction of the laminar flame speeds and Markstein lengths extracted from propagating spherical flames. Since radiation and compression both exist in the experiments on ultra-lean methane/air mixtures reported in the literature, the measured laminar flame speeds and Markstein lengths are much lower than results from simulation and thus cannot be used for kinetic mechanism validation. (author)
I. Radinschi; Th. Grammenos
2005-08-01
We use Moeller's energy-momentum complex in order to explicitly compute the energy and momentum density distributions for an exact solution of Einstein's field equations with a negative cosmological constant minimally coupled to a static massless scalar field in a static, spherically symmetric background in (2+1)-dimensions.
Collins, Gary S.
Finite Element Analysis of Spherical Indentation Tests John Homans1, Sinisa Dj. Mesarovic2, Harish finite element analysis program Abaqus 6.7. · Runs were repeated using a dense mesh to ensure accuracy not influence the solution. Objective · Develop a finite element model to analyze: i) Load-depth response
Wu, Ke-Li
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 51, NO. 10, OCTOBER 2003 2801 A Plane Wave Expansion of Spherical Wave Functions for Modal Analysis of Guided Wave Structures and Scatterers Robert H. MacPhie, Life Fellow, IEEE, and Ke-Li Wu, Senior Member, IEEE Abstract--A new finite plane wave series
Tewari, Aarti; Walia, Ritu; Sharma, Suresh C.
2012-01-15
The role of negatively charged ions in plasma on growth (without catalyst) and field emission properties of spherical carbon nanotube (CNT) tip has been theoretically investigated. A theoretical model of charge neutrality, including the kinetics of electrons, negatively and positively charged ions, neutral atoms, and the energy balance of various species has been developed. Numerical calculations of the spherical CNT tip radius for different relative density of negatively charged ions {epsilon}{sub r}(=n{sub SF{sub 6{sup -}}}/n{sub C{sup +}}, where n{sub SF{sub 6{sup -}}} and n{sub C}{sup +} are the equilibrium densities of sulphur hexafluoride and carbon ions, respectively) have been carried out for the typical glow discharge plasma parameters. It is found that the spherical CNT tip radius decreases with {epsilon}{sub r} and hence the field emission of electrons from the spherical CNT tip increases. Some of our theoretical results are in accordance with the existing experimental observations.
Sandia Energy - National SCADA Testbed
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National SCADA Testbed Home Stationary Power Safety, Security & Resilience of Energy Infrastructure Grid Modernization Cyber Security for Electric Infrastructure National...
G. S. Bisnovatyi-Kogan; O. Yu. Tsupko
2015-07-24
In this paper we review a recently developed approximate method for investigation of dynamics of compressible ellipsoidal figures. Collapse and subsequent behaviour are described by a system of ordinary differential equations for time evolution of semi-axes of a uniformly rotating, three-axis, uniform-density ellipsoid. First, we apply this approach to investigate dynamic stability of non-spherical bodies. We solve the equations that describe, in a simplified way, the Newtonian dynamics of a self-gravitating non-rotating spheroidal body. We find that, after loss of stability, a contraction to a singularity occurs only in a pure spherical collapse, and deviations from spherical symmetry prevent the contraction to the singularity through a stabilizing action of nonlinear non-spherical oscillations. The development of instability leads to the formation of a regularly or chaotically oscillating body, in which dynamical motion prevents the formation of the singularity. We find regions of chaotic and regular pulsations by constructing a Poincare diagram. A real collapse occurs after damping of the oscillations because of energy losses, shock wave formation or viscosity. We use our approach to investigate approximately the first stages of collapse during the large scale structure formation. The theory of this process started from ideas of Ya. B. Zeldovich, concerning the formation of strongly non-spherical structures during nonlinear stages of the development of gravitational instability, known as 'Zeldovich's pancakes'. In this paper the collapse of non-collisional dark matter and the formation of pancake structures are investigated approximately. We estimate an emission of very long gravitational waves during the collapse, and discuss the possibility of gravitational lensing and polarization of the cosmic microwave background by these waves.
National Ignition Facility | National Nuclear Security Administration
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformationJessework usesofPublications TheScience (SC) National2015 | National Nuclear
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guy" and "a very hard worker." Fanelli began his college education in his native Argentina. By 2005, he was stationed at the National High Magnetic Field Laboratory...
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You can find publications, including technical papers and reports, about geothermal technologies, research, and development at the following U.S. Department of Energy national laboratories.
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Nuclear Fuel Grand BC and High-Level Radioactive Waste - Jeff Williams, Director, Nuclear Fuel Storage and Transportation Planning Project, DOEOffice of Nuclear Energy National...
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The Seneca Nation of Indians (SNI) will install one 1.8-megawatt (MW) wind turbine on tribal common lands near Lake Erie in New York.
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2010-01-01
Ames Laboratory observed the National Day of Remembrance for weapons workers from the Cold War era with a ceremony held Oct. 27, 2009 at the Ames Public Library.
Los Alamos National Laboratory
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Lawrence Livermore National Laboratory's weapon-physicist Greg Spriggs, leader of the Film Scanning and Reanalysis Project, the work has become a search-and-rescue mission. He...
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VPPPA Conference August 19, 2012 Subcontractor Selection & Alignment Mark Manderbach, Steve Maki, J. Manuel Aguirre National VPPPA Conference August 19, 2012 Mark Manderbach, Steve...
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3, 2015 Projects save taxpayer dollars, promote environmental stewardship, sustainability LOS ALAMOS, N.M., April 22, 2015-Nearly 400 Los Alamos National Laboratory employees on 32...
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RES Las Vegas is another multifaceted event from The National Center which will feature unparalleled access to respected tribal leaders, members of congress, federal agency representatives, state...
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The American Public Power Association (APPA) is hosting their national conference that covers the political, economic, and technological trends shaping the electric utility industry.
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the Earth's Surface. The second virtual classroom to the student was presented by Tommy Smith from Lawrence Livermore National Laboratory on various sources of energy, its use and...
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Ames Laboratory observed the National Day of Remembrance for weapons workers from the Cold War era with a ceremony held Oct. 27, 2009 at the Ames Public Library.
National Nuclear Security Administration
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Washington, DC 20585 MEMORANDUM FOR THE ADMINISTRATOR FROM: THEODORE D. SHERRY II 4 flA. * -. SUBJECT: REFERENCE: NATIONAL SECURITY ENTI's'E FIELD COUNCIL CHAIR ACTION:...
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rate. Reserve a room at Embassy Suites Albuquerque About the NTSF The NTSF is the mechanism through which the DOE communicates with states and tribal nations about DOE's...
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POC Technologies Center, funded by a National Institutes of Biomedical Imaging and Bioengineering (NIBIB) U54 award, focuses on advancing critical-emergency-disaster care by...
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The U.S. Department of Energy (DOE) is participating in a National Tribal Energy Summit September 23–25, 2015, in Washington, D.C. The National Summit supports the Obama Administration’s ongoing commitment to assist tribal efforts to enhance energy security, increase community resiliency, and cultivate a sustainable energy future.
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The National Cancer Institute, International Cancer Information Center Bldg. 82, Rm 123 Bethesda, MD 20892 The National Cancer Institute (NCI) is part of the Federal Government. NCI coordinates the government's cancer research program. It is the largest of the 17 biomedical research institutes and centers
Increase in the energy density of the pinch plasma in 3D implosion of quasi-spherical wire arrays
Aleksandrov, V. V., E-mail: alexvv@triniti.ru [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Gasilov, V. A. [Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation); Grabovski, E. V.; Gritsuk, A. N., E-mail: griar@triniti.ru; Laukhin, Ya. N.; Mitrofanov, K. N.; Oleinik, G. M. [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Ol’khovskaya, O. G. [Russian Academy of Sciences, Keldysh Institute of Applied Mathematics (Russian Federation); Sasorov, P. V.; Smirnov, V. P.; Frolov, I. N. [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Shevel’ko, A. P. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)
2014-12-15
Results are presented from experimental studies of the characteristics of the soft X-ray (SXR) source formed in the implosion of quasi-spherical arrays made of tungsten wires and metalized kapron fibers. The experiments were carried out at the Angara-5-1 facility at currents of up to 3 MA. Analysis of the spatial distribution of hard X-ray emission with photon energies above 20 keV in the pinch images taken during the implosion of quasi-spherical tungsten wire arrays (QTWAs) showed that a compact quasi-spherical plasma object symmetric with respect to the array axis formed in the central region of the array. Using a diffraction grazing incidence spectrograph, spectra of SXR emission with wavelengths of 20–400 Å from the central, axial, and peripheral regions of the emission source were measured with spatial resolutions along the array radius and height in the implosion of QTWAs. It is shown that the emission spectra of the SXR sources formed under the implosion of quasi-spherical and cylindrical tungsten wire arrays at currents of up to 3 MA have a maximum in the wavelength range of 50–150 Å. It is found that, during the implosion of a QTWA with a profiled linear mass, a redistribution of energy in the emission spectrum takes place, which indicates that, during 3D implosion, the energy of longitudinal motion of the array material additionally contributes to the radiation energy. It is also found that, at close masses of the arrays and close values of the current in the range of 2.4{sup ?3} MA, the average energy density in the emission source formed during the implosion of a quasi-spherical wire array is larger by a factor of 7 than in the source formed during the implosion of a cylindrical wire array. The experimental data were compared with results of 3D simulations of plasma dynamics and radiation generation during the implosion of quasi-spherical wire arrays with a profiled mass by using the MARPLE-3D radiative magnetohydrodynamic code, developed at the Keldysh Institute of Applied Mathematics, Russian Academy of Sciences.
Spherically symmetric solution of $f(R,\\mathcal{G})$ gravity at low energy
Wu, Bofeng
2015-01-01
The weak-field and slow-motion limit of $f(R,\\mathcal{G})$ gravity is developed up to $(v/c)^{4}$ order in a spherically symmetric background. Considering the Taylor expansion of a general function $f$ around vanishing values of $R$ and $\\mathcal{G}$, we present general vacuum solutions up to $(v/c)^{4}$ order for the gravitational field generated by a ball-like source. The spatial behaviors at $(v/c)^{2}$ order are the same for $f(R,\\mathcal{G})$ gravity and $f(R)$ gravity, and their corresponding real valued static behaviors are presented and compared with the one in general relativity. The static Yukawa-like behavior is proved to be compatible with the previous result of the most general fourth-order theory. At $(v/c)^{4}$ order, the static corrections to the Yukawa-like behavior for $f(R,\\mathcal{G})$ gravity, $f(R)$ gravity, and the Starobinsky gravity are presented and compared with the one in general relativity.
Spherically symmetric solution of $f(R,\\mathcal{G})$ gravity at low energy
Bofeng Wu; Bo-Qiang Ma
2015-10-29
The weak-field and slow-motion limit of $f(R,\\mathcal{G})$ gravity is developed up to $(v/c)^{4}$ order in a spherically symmetric background. Considering the Taylor expansion of a general function $f$ around vanishing values of $R$ and $\\mathcal{G}$, we present general vacuum solutions up to $(v/c)^{4}$ order for the gravitational field generated by a ball-like source. The spatial behaviors at $(v/c)^{2}$ order are the same for $f(R,\\mathcal{G})$ gravity and $f(R)$ gravity, and their corresponding real valued static behaviors are presented and compared with the one in general relativity. The static Yukawa-like behavior is proved to be compatible with the previous result of the most general fourth-order theory. At $(v/c)^{4}$ order, the static corrections to the Yukawa-like behavior for $f(R,\\mathcal{G})$ gravity, $f(R)$ gravity, and the Starobinsky gravity are presented and compared with the one in general relativity.
Geometrical properties of the trans-spherical solutions in higher dimensions
Kang, Gungwon; Kim, Hyeong-Chan; Lee, Jungjai
2009-06-15
We investigate the geometrical properties of static vacuum p-brane solutions of Einstein gravity in D=n+p+3 dimensions, which have spherical symmetry of S{sup n+1} orthogonal to the p directions and which are invariant under the translation along them. The solutions are characterized by the mass density and p number of tension densities. The causal structure of the higher-dimensional solutions is essentially the same as that of the five-dimensional ones. Namely, a naked singularity appears for most solutions except for the Schwarzschild black p-brane and the Kaluza-Klein bubble. We show that some important geometric properties such as the area of S{sup n+1} and the total spatial volume are characterized only by the three parameters (the mass density, the sum of tension densities, and the sum of tension density squares), rather than individual tension densities. These geometric properties are analyzed in detail in this parameter space and are compared with those of the five-dimensional case.
HYDRODYNAMICS OF CORE-COLLAPSE SUPERNOVAE AT THE TRANSITION TO EXPLOSION. I. SPHERICAL SYMMETRY
Fernandez, Rodrigo [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States)
2012-04-20
We study the transition to runaway expansion of an initially stalled core-collapse supernova shock. The neutrino luminosity, mass accretion rate, and neutrinospheric radius are all treated as free parameters. In spherical symmetry, this transition is mediated by a global non-adiabatic instability that develops on the advection time and reaches nonlinear amplitude. Here, we perform high-resolution, time-dependent hydrodynamic simulations of stalled supernova shocks with realistic microphysics to analyze this transition. We find that radial instability is a sufficient condition for runaway expansion if the neutrinospheric parameters do not vary with time and if heating by the accretion luminosity is neglected. For a given unstable mode, transition to runaway occurs when fluid in the gain region reaches positive specific energy. We find approximate instability criteria that accurately describe the behavior of the system over a wide region of parameter space. The threshold neutrino luminosities are in general different than the limiting value for a steady-state solution. We hypothesize that multidimensional explosions arise from the excitation of unstable large-scale modes of the turbulent background flow, at threshold luminosities that are lower than in the laminar case.
Dynamical response to supernova-induced gas removal in two-component spherical galaxies
Masahiro Nagashima; Yuzuru Yoshii
2002-12-30
We investigate dynamical response on size and velocity dispersion to mass loss by supernovae in formation of two-component spherical galaxies composed of baryon and dark matter. Three-dimensional deprojected de Vaucouleurs-like and exponential-like profiles for baryon, embedded in truncated singular isothermal and homogeneous profiles for dark matter, are considered. As a more realistic case, we also consider a dark matter profile proposed by Navarro, Frenk & White. For simplicity we assume that dark matter distribution is not affected by mass loss and that the change of baryonic matter distribution is homologous. We found that the degree of the response depends on the fraction of dark matter in the region where baryon is distributed, so that dwarf spheroidal galaxies would be affected even in a dark halo if they are formed by galaxy mergers in the envelope of the dark halo. Our results suggest that this scenario, combined with dynamical response, would make not only the observed trends but the dispersed characteristics of dwarf spheroidals.
Prospects for pilot plants based on the tokamak, spherical tokamak and stellarator.
Menard, J. E. [Princeton Plasma Physics Laboratory (PPPL); Bromberg, L. [Massachusetts Institute of Technology (MIT); Brown, T. [Princeton Plasma Physics Laboratory (PPPL); Burgess, Thomas W [ORNL; Dix, D. [School of Engineering and Applied Sciene, Princeton University, Princeton, NJ, USA; El-GuebalyUniv. Wisco, L. [University of Wisconsin; Gerrity, T. [Massachusetts Institute of Technology (MIT); Goldston, R. J. [Princeton Plasma Physics Laboratory (PPPL); Hawryluk, R. [Princeton Plasma Physics Laboratory (PPPL); Kastner, R. [School of Engineering and Applied Sciene, Princeton University, Princeton, NJ, USA; Kessel, C. [Princeton Plasma Physics Laboratory (PPPL); Malang, S. [Fusion Nuclear Technology Consulting, Germany; Minervini, J. [Massachusetts Institute of Technology (MIT); Neilson, G. H. [Princeton Plasma Physics Laboratory (PPPL); Neumeyer, C. L. [Princeton Plasma Physics Laboratory (PPPL); Prager, S. [Princeton Plasma Physics Laboratory (PPPL); Sawan, M. [University of Wisconsin; Sheffield, J. [Inistitute for a Secure and Sustainable Environment, University of Tennessee, Knoxville, TN, USA; Sternlieb, A. [Israel Ministry of Defense, Tel Aviv, Israel; Waganer, L. [Consultant; Whyte, D. G. [Massachusetts Institute of Technology (MIT); Zarnstorff, M. C. [Princeton Plasma Physics Laboratory (PPPL)
2011-01-01
A potentially attractive next-step towards fusion commercialization is a pilot plant, i.e. a device ultimately capable of small net electricity production in as compact a facility as possible and in a configuration scalable to a full-size power plant. A key capability for a pilot-plant programme is the production of high neutron fluence enabling fusion nuclear science and technology (FNST) research. It is found that for physics and technology assumptions between those assumed for ITER and nth-of-a-kind fusion power plant, it is possible to provide FNST-relevant neutron wall loading in pilot devices. Thus, it may be possible to utilize a single facility to perform FNST research utilizing reactor-relevant plasma, blanket, coil and auxiliary systems and maintenance schemes while also targeting net electricity production. In this paper three configurations for a pilot plant are considered: the advanced tokamak, spherical tokamak and compact stellarator. A range of configuration issues is considered including: radial build and blanket design, magnet systems, maintenance schemes, tritium consumption and self-sufficiency, physics scenarios and a brief assessment of research needs for the configurations.
Suresh, Anil K [ORNL; Pelletier, Dale A [ORNL; Wang, Wei [ORNL; Broich, Michael L [ORNL; Moon, Ji Won [ORNL; Gu, Baohua [ORNL; Allison, David P [ORNL; Joy, David Charles [ORNL; Phelps, Tommy Joe [ORNL; Doktycz, Mitchel John [ORNL
2011-01-01
Nanocrystallites have garnered substantial interest due to their varying applications including catalysis. Consequently important aspects related to control of shape/size and syntheses through economical and non-hazardous means are desirable. Highly efficient bioreduction based natural fabrication approaches that utilize microbes and or -plant extracts are poised to meet these needs. Here we show that the gamma- proteobacterium, Shewanella oneidensis MR-1, can reduce tetrachloro aurate (III) ions, producing discrete extracellular spherical gold nanocrystallites. The particles were homogeneous with multiple size distributions and produced under ambient conditions at high yield, 88% of theoretical maximum. Further characterization revealed that the particles consist of spheres in the size range of 2-50 nm, with an average of 12 5 nm. The nanoparticles were hydrophilic, biocompatible, and resisted aggregation even after several months. The particles are likely capped by a detachable protein/peptide coat. UV-vis and Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray spectra and transmission electron microscopy measurements confirmed the formation as well the crystalline nature of the nanoparticles. The antibacterial activity of these gold nanoparticles was assessed using Gram-negative (E. coli and S. oneidensis) and Gram-positive (B. subtilis) bacteria. Toxicity assessments divulged that the particles were neither toxic nor inhibitory to any of these bacteria.
Literature Review of Spherical Resorcinol-Formaldehyde for Cesium Ion Exchange
Brown, Garrett N.
2014-09-30
The current report summarizes work performed throughout the scientific community and DOE complex as reported in the open literature and DOE-sponsored reports to evaluate the Cs+ ion exchange (CIX) characteristics of SRF resin. King (2007) completed a similar literature review in support of material selection for the Small Column Ion Exchange (SCIX) project. Josephson et al. (2010) and Sams et al. (2009) provided a similar brief review of SRF CIX for the near-tank Cs+ removal (NTCR) project. Thorson (2008a) documented the basis for recommending SRF over SuperLigTM 644 as the primary CIX resin in the WTP. The current review expands on previous work, summarizes additional work completed to date, and provides a broad view of the literature without focusing on a specific column system. Although the focus of the current review is the SRF resin, many cited references include multiple materials such as the non-spherical GGRF and SuperLigTM 644 organic resins and crystalline silicotitanate (CST) IONSIVTM IE-911, a non-elutable inorganic material. This report summarizes relevant information provided in the literature.
Redirection of the spherical expanding shock wave on the interface with plasma
Markhotok, A.; Popovic, S.
2014-02-15
We study a strong spherical expanding shock wave interacting with the finite-gradient interface between neutral cold gas and weakly ionized plasma. We want to see how the interaction with the interface can alter the shock structure compared to the case of its free propagation through the media with the exponentially varying density. From our comparative calculations based on the 2D model, we found substantial difference in the shock structure including strong deformation of the shock front followed with its gradual flattening and the redirection in its propagation. There are a number of factors that can be used to control this phenomenon in order to strengthen or lessen the effect. The calculations can be made on any scale, limited with the requirement for the shock wave to be strong. The study points at the possibility in certain applications to avoid the shock wave with its redirection rather than attenuation. The results can be applicable to optimization of the energy deposition into the supersonic flux, the drag reduction in hypersonic flight, in the detonation theory, and combustion through the control of the ignition conditions, and for environmental improvements through sonic boom reduction. Cartesian coordinates were used in order to visualize the phenomenon.
Final State of Spherical Gravitational Collapse and Likely Source of Gamma Ray Bursts
Abhas Mitra
2000-12-11
Following our result that for the final state of continued spherical gravitational collapse, the gravitational mass of the fluid, $M_f\\to 0$, we show that for a physical fluid the eventual value of $2GM_f/R_f\\to 1$ rather than $2GM_f/R_f <1$, indicating approach to a zero-mass black hole. We also indicate that as the final state would be approached, the curvature components tend to blow up, and the proper radial distance $l$ and the proper time $\\tau \\to \\infty$. This indicates that actually the singularity is never attained for the collapse of an isolated body. We also identify that, the final state may correspond to the local 3-speed $v\\to c$, eventhough the circumference speed $U\\to 0$. However, at a finite observation epoch, such Eternally Collapsing Objects (ECOs) may have a modest local speed of collapse $v \\ll c$, and the lab frame speed of collapse should practically be zero because of their extremely high surface gravitational red-shifts.
Towards the Final State of Spherical Gravitational Collapse and Likely Source of Gamma Ray Bursts
Abhas Mitra
1999-09-23
We invoke the global properties of the actual GTR field equations for spherical collapse to directly show that the condition for formation of trapped surfaces, 2GM/R >1 is not allowed by GTR. And therefore all singularity theorems based on the assumption of formation of trapped surfaces are invalidated! Our conclusion is in perfect agreement with Einstein's intuitive idea that a Sch. like surface can not occur in reality. Further as singularity is approached R ->0, in order that 2GM/R 0! Harrison, et al. had also pointed out that collapse should come to a decisive end with M=0. This is possible in GTR if the fluid radiates its entire original mass-energy during the relentless graviatational contraction process, Q->M c^2! Since the actual efficiency for gamma ray production by the relevant blast wave may hardly exceed 10-20% and there could be a stronger (undetected) nu-anti-nu burst precding GRBs, the actual energy released for GRB 990123, even accounting for probable weak beaming, or for GRB 971214 (unbeamed) could be ~10^{54-55} erg. And such energy release may not be properly accountable without realizing that trapped surfaces are indeed not formed. All authors concerned with this subject, and particularly those, who would like to differ with our derivation are requested to send their criticism either directly or express the same openly for a healthy scientific discussion.
Hanumantha Rao Vutukuri; Arnout Imhof; Alfons van Blaaderen
2015-01-12
Particle shape is a critical parameter that plays an important role in self-assembly, for example, in designing targeted complex structures with desired properties. In the last decades an unprecedented range of monodisperse nanoparticle systems with control over the shape of the particles have become available. In contrast, the choice of micron-sized colloidal building blocks of particles with flat facets, i.e., particles with polygonal shapes, is significantly more limited. This can be attributed to the fact that, contrary to nanoparticles, the larger colloids are significantly harder to synthesize as single crystals. Herein, we demonstrate that the simplest building block, such as the micron-sized polymeric spherical colloidal particle, is already enough to fabricate particles with regularly placed flat facets, including completely polygonal shapes with sharp edges. As an illustration that the yields are high enough for further self-assembly studies we demonstrate the formation of 3D rotator phases of fluorescently labelled, micron-sized and charged rhombic dodecahedron particles. Our method for fabricating polyhedral particles opens a new avenue for designing new materials.
Linear stability and nonlinear dynamics of the fishbone mode in spherical tokamaks
Wang, Feng; Liu, J. Y. [School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116024 (China)] [School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116024 (China); Fu, G. Y.; Breslau, J. A. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
2013-10-15
Extensive linear and nonlinear simulations have been carried out to investigate the energetic particle-driven fishbone instability in spherical tokamak plasmas with weakly reversed q profile and the q{sub min} slightly above unity. The global kinetic-MHD hybrid code M3D-K is used. Numerical results show that a fishbone instability is excited by energetic beam ions preferentially at higher q{sub min} values, consistent with the observed appearance of the fishbone before the “long-lived mode” in MAST and NSTX experiments. In contrast, at lower q{sub min} values, the fishbone tends to be stable. In this case, the beam ion effects are strongly stabilizing for the non-resonant kink mode. Nonlinear simulations show that the fishbone saturates with strong downward frequency chirping as well as radial flattening of the beam ion distribution. An (m, n) = (2, 1) magnetic island is found to be driven nonlinearly by the fishbone instability, which could provide a trigger for the (2, 1) neoclassical tearing mode sometimes observed after the fishbone instability in NSTX.
A simplified spherical harmonic method for coupled electron-photon transport calculations
Josef, J.A.
1997-12-01
In this thesis the author has developed a simplified spherical harmonic method (SP{sub N} method) and associated efficient solution techniques for 2-D multigroup electron-photon transport calculations. The SP{sub N} method has never before been applied to charged-particle transport. He has performed a first time Fourier analysis of the source iteration scheme and the P{sub 1} diffusion synthetic acceleration (DSA) scheme applied to the 2-D SP{sub N} equations. The theoretical analyses indicate that the source iteration and P{sub 1} DSA schemes are as effective for the 2-D SP{sub N} equations as for the 1-D S{sub N} equations. In addition, he has applied an angular multigrid acceleration scheme, and computationally demonstrated that it performs as well as for the 2-D SP{sub N} equations as for the 1-D S{sub N} equations. It has previously been shown for 1-D S{sub N} calculations that this scheme is much more effective than the DSA scheme when scattering is highly forward-peaked. The author has investigated the applicability of the SP{sub N} approximation to two different physical classes of problems: satellite electronics shielding from geomagnetically trapped electrons, and electron beam problems.
Traugott, Hadar
2015-01-01
Turbulent resuspension is the process of lifting solid particles from the bottom by turbulent flow, ubiquitous in natural and industrial problems. The process is a sequence of events that start with an incipient motion when the particle is dislodged from its place, continue as sliding or rolling along the surface, and ending with the detachment of the particle from the surface and lifting it up into the flow. In this study we measure in details the motion of freely moving solid spherical particles along the bottom smooth wall under an oscillating grid turbulence and track them through the lift-off events. We measure simultaneously the Lagrangian trajectories of the particles and the flow tracers around them. We estimate the local flow parameters and extract the different force terms that act on a particle. For the particles of the diameter comparable with the Kolmogorov length scale, either sliding or rolling along the smooth wall under a zero-mean turbulent flow, we find that: i) the lift force is a dominant...
Jacobi stability of the vacuum in the static spherically symmetric brane world models
Harko, T.; Sabau, V. S. [Department of Physics and Center for Theoretical and Computational Physics, University of Hong Kong, Pok Fu Lam Road (Hong Kong); Department of Mathematics, Hokkaido Tokai University, 5-1-1-1 Minamisawa, Minami-ku, Sapporo, 005-8601 (Japan)
2008-05-15
We analyze the stability of the structure equations of the vacuum in the brane world models, by using both the linear (Lyapunov) stability analysis, and the Jacobi stability analysis, the Kosambi-Cartan-Chern theory. In the brane world models the four-dimensional effective Einstein equations acquire extra terms, called dark radiation and dark pressure, respectively, which arise from the embedding of the three-brane in the bulk. Generally, the spherically symmetric vacuum solutions of the brane gravitational field equations have properties quite distinct as compared to the standard black hole solutions of general relativity. We close the structure equations by assuming a simple linear equation of state for the dark pressure. In this case the vacuum is Jacobi stable only for a small range of values of the proportionality constant relating the dark pressure and the dark radiation. The unstable trajectories on the brane behave chaotically, in the sense that after a finite radial distance it would be impossible to distinguish the trajectories that were very near each other at an initial point. Hence the Jacobi stability analysis offers a powerful method for constraining the physical properties of the vacuum on the brane.
A quasi-Bohmian approach for a homogeneous spherical solid body based on its geometric structure
Koupaei, Jalaledin Yousefi; Institutes for Theoretical Physics and Mathematics , Tehran ; Golshani, Mehdi; Department of Physics, Sharif University of Technology, Tehran
2013-12-15
In this paper we express the space of rotation as a Riemannian space and try to generalize the classical equations of motion of a homogeneous spherical solid body in the domain of quantum mechanics. This is done within Bohm's view of quantum mechanics, but we do not use the Schrödinger equation. Instead, we assume that in addition to the classical potential there is an extra potential and try to obtain it. In doing this, we start from a classical picture based on Hamilton-Jacobi formalism and statistical mechanics but we use an interpretation which is different from the classical one. Then, we introduce a proper action and extremize it. This procedure gives us a mathematical identity for the extra potential that limits its form. The classical mechanics is a trivial solution of this method. In the simplest cases where the extra potential is not a constant, a mathematical identity determines it uniquely. In fact the first nontrivial potential, apart from some constant coefficients which are determined by experiment, is the usual Bohmian quantum potential.
Response of a water-filled spherical vessel to an internal explosion
Lewis, M.W.; Wilson, T.L.
1997-06-01
Many problems of interest to the defense community involve fluid-structure interaction (FSI). Such problems include underwater blast loading of structures, bubble dynamics and jetting around structures, and hydrodynamic ram events. These problems may involve gas, fluid, and solid dynamics, nonlinear material behavior, cavitation, reaction kinetics, material failure, and nonlinearity that is due to varying geometry and contact conditions within a structure or between structures. Here, the authors model the response of a water-filled, thick-walled, spherical steel vessel to an internal explosion of 30 grams of C-4 with FSI2D--a two-dimensional coupled finite element and finite volume hydrodynamics code. The gas phase detonation products were modeled with a Becker-Kistiakowsky-Wilson high-explosive equation of state. Predictions from a fully coupled model were compared to experimental results in the form of strain gauge traces. Agreement was reasonably good. Additionally, the calculation was run in an uncoupled mode to understand the importance of fluid-structure interaction in this problem. The uncoupled model results in an accumulation of nonphysical energy in the vessel.
Structure, thermodynamic properties, and phase diagrams of few colloids confined in a spherical pore
Iván Paganini; Claudio Pastorino; Ignacio Urrutia
2015-04-09
We study a system of few colloids confined in a small spherical cavity by event driven molecular dynamics simulations in the canonical ensemble. The colloidal particles interact through a short range square-well potential, which takes into account the basic elements of attraction and excluded-volume repulsion of the interaction among colloids. We analyze the structural and thermodynamic properties of this few-body confined system in the framework of the theory of inhomogeneous fluids. Pair correlation functions and density profiles across the cavity are used to determine the structure of the system and the spatial characteristics of its inhomogeneities. Pressure on the walls, internal energy and surface quantities such as surface tension and adsorption are also analyzed for the whole range of densities, temperatures and number of particles considered. We have characterized the structure of systems from 2 to 6 confined particles as function of density and temperature, identifying the distinctive qualitative behaviors all over the thermodynamic plane $T-\\rho$ in a few-particle equivalence to phase diagrams of macroscopic systems. Applying the extended law of corresponding states the square well interaction is mapped to the Asakura-Oosawa model for colloid-polymer mixtures. We link explicitly the temperature in the confined square-well fluid to the equivalent packing fraction of polymers in the Asakura-Oosawa model. Using this approach we study the confined system of few colloids in a colloid-polymer mixture.
Diez Muino, R.; Rolles, D.; Garcia de Abajo, F.J.; Fadley, C.S.; Van Hove, M.A.
2001-09-06
We use multiple scattering in non-spherical potentials (MSNSP) to calculate the angular distributions of electrons photoemitted from the 1s-shells of CO and N2 gas-phase molecules with fixed-in-space orientations. For low photoelectron kinetic energies (E<50 eV), as appropriate to certain shape-resonances, the electron scattering must be represented by non-spherical scattering potentials, which are naturally included in our formalism. Our calculations accurately reproduce the experimental angular patterns recently measured by several groups, including those at the shape-resonance energies. The MSNSP theory thus enhances the sensitivity to spatial electronic distribution and dynamics, paving the way toward their determination from experiment.
Misra, Shikha [Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi-110016 (India); Mishra, S. K. [Institute for Plasma Research, Gandhinagar-382428 (India); Sodha, M. S. [Department of Education Building, University of Lucknow, Lucknow-226007 (India)
2013-01-15
The authors have modified Chow's theory of secondary electron emission (SEE) to take account of the fact that the path length of a primary electron in a spherical particle varies between zero to the diameter or x{sub m} the penetration depth depending on the distance of the path from the centre of the particle. Further by including this modified expression for SEE efficiency, the charging kinetics of spherical grains in a Maxwellian plasma has been developed; it is based on charge balance over dust particles and number balance of electrons and ionic species. It is seen that this effect is more pronounced for smaller particles and higher plasma temperatures. Desirable experimental work has also been discussed.
Tominaga, Nozomu; Blinnikov, Sergei I
2015-01-01
We develop a time-dependent multi-group multidimensional relativistic radiative transfer code, which is required to numerically investigate radiation from relativistic fluids involved in, e.g., gamma-ray bursts and active galactic nuclei. The code is based on the spherical harmonic discrete ordinate method (SHDOM) that evaluates a source function including anisotropic scattering in spherical harmonics and implicitly solves the static radiative transfer equation with a ray tracing in discrete ordinates. We implement treatments of time dependence, multi-frequency bins, Lorentz transformation, and elastic Thomson and inelastic Compton scattering to the publicly available SHDOM code. Our code adopts a mixed frame approach; the source function is evaluated in the comoving frame whereas the radiative transfer equation is solved in the laboratory frame. This implementation is validated with various test problems and comparisons with results of a relativistic Monte Carlo code. These validations confirm that the code ...
Zhe Chang; Cheng-Bo Guan; Chao-Guang Huang; Xin Li
2008-03-26
We investigate the gravitational collapse of a spherically symmetric, inhomogeneous star, which is described by a perfect fluid with heat flow and satisfies the equation of state $p=\\rho/3$ at its center. In the process of the gravitational collapsing, the energy of the whole star is emitted into space. And the remaining spacetime is a Minkowski one without a remnant at the end of the process. For a star with a solar mass and solar radius, the total energy emitted is at the order of $10^{54}$ {\\rm erg}, and the time-scale of the process is about $8s$. These are in the typical values for a gamma-ray burst. Thus, we suggest the gravitational collapse of a spherical star with heat flow as a possible energy mechanism of gamma-ray bursts.
Arrieta, Eduardo
1986-01-01
the adoption of a model fluid. We choose a monatomic fluid (spherical particles) subject to an isotropic (orientation- independent) interaction potential, specificaIIy a hard-core Yukawa potential (see Eq. (8) in subsection II. A where we also explain..., computational procedure for the calculation of the MSA thermodynamic and structural properties of binary mixtures of hard-core fluids with single Yukawa interactions. Since such model systems are qualitatively realistic, we expect this method to provide...
Ujjal Debnath; Mubasher Jamil
2015-01-03
In this work, we focus on the collapse of a spherically symmetric perturbation, with a classical top-hat profile, to study the nonlinear evolution of only viscous modified Chaplygin gas (VMCG) perturbations in Einstein's gravity as well as in loop quantum Cosmology (LQC). In the perturbed region, we have investigated the natures of equation of state parameter, square speed of sound and another perturbed quantities. The results have been analyzed by numerical and graphical investigations.
The fluxes of CN neutrinos from the Sun in case of mixing in a spherical layer in the solar core
Kopylov, Anatoly; Petukhov, Valery E-mail: beril@inr.ru
2012-03-01
The results of the calculation are presented for the fluxes of CN neutrinos from the Sun in case of mixing in a spherical layer in the solar core, consistent with the seismic data and with the measured solar neutrino fluxes. It is shown that a substantial increase of the flux of {sup 13}N neutrinos can be gained in this case. The possible implications for experiment are discussed.
NNSA Celebrates National Nuclear Science Week | National Nuclear...
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National Nuclear Science Week | National Nuclear Security Administration Facebook Twitter Youtube Flickr RSS People Mission Managing the Stockpile Preventing Proliferation Powering...
National Aeronautics and Space Administration
Rathbun, Julie A.
,,/ NASA National Aeronautics and Space Administration Lyndon B. Johnson Space Center Houston by the National Aeronautics and Space Administration ii Hosted by the National Academy of Sclences for library, abstract service, educational, or research purposes; however, republication of any paper
Biomass Feedstock National User Facility
Office of Energy Efficiency and Renewable Energy (EERE)
Breakout Session 1B—Integration of Supply Chains I: Breaking Down Barriers Biomass Feedstock National User Facility Kevin L. Kenney, Director, Biomass Feedstock National User Facility, Idaho National Laboratory
BROADER National Security Missions
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Metal Chips (U) Uranium Trioxide (UO 3 ) UO 2 (NO 3 ) 2 Ur anyl Nitrate Ammonium Uranyl Carbonate (NH 4 ) 2 UO 2 (CO 3 ) 4 DEVELOP NEW NATIONAL SECURITY MISSIONS Y-12 has...
Brookhaven National Laboratory
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Site OverviewThe Brookhaven National Laboratory (BNL) was established in 1947 by the Atomic Energy Commission (AEC) (predecessor to U.S. Department of Energy [DOE]). Formerly Camp Upton, a U.S....
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measurement LOS ALAMOS, New Mexico, July 10, 2012-Using a one-of-a-kind laser system at Los Alamos National Laboratory, scientists have created the largest neutron beam...
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is now a member of the National Academy of Sciences and France's Legion of Honor. He is Sterling Professor of Mathematics Emeritus, at Yale University and Fellow Emeritus of...
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Hazardous devices teams showcase skills at Robot Rodeo June 24-27 June 18, 2014 Bomb squads compete in timed scenarios at Los Alamos National Laboratory LOS ALAMOS, N.M., June 19,...
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takes part in Blue Star Museums program May 16, 2012 Free admission for active duty military, their family members LOS ALAMOS, New Mexico, May 16, 2012-Los Alamos National...