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
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)
2004-12-01T23:59:59.000Z
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.
Implementation of BN Control in the National Spherical Torus Experiment
Gerhardt, S; Bell, M G; Cropper, M; Gates, D A; Koleman, E; Lawson, J; Marsala, B; Menard, J E; Mueller, D
2012-09-15T23:59:59.000Z
We have designed and constructed a system for control of 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 of B N (from realtime equilibrium reconstruction) and a time-dependent request, in order to calculate the required injected power. This injected power request is then turned into modulations of the neutral beams. The details of this algorithm are described, including the techniques used to develop the appropriate control gains. Example uses of the system are shown
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
2008-08-04T23:59:59.000Z
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.
Measurement of Poloidal Velocity on the National Spherical Torus Experiment
Ronald E. Bell and Russell Feder
2010-06-04T23:59:59.000Z
A diagnostic suite has been developed to measure impurity poloidal flow using charge exchange recombination spectroscopy on the National Spherical Torus Experiment. Toroidal and poloidal viewing systems measure all quantities required to determine the radial electric field. Two sets of up/down symmetric poloidal views are used to measure both active emission in the plane of the neutral heating beams and background emission in a radial plane away from the neutral beams. Differential velocity measurements isolate the line-integrated poloidal velocity from apparent flows due to the energy-dependent chargeexchange cross section. Six f/1.8 spectrometers measure 276 spectra to obtain 75 active and 63 background channels every 10 ms. Local measurements from a similar midplane toroidal viewing system are mapped into two dimensions to allow the inversion of poloidal line-integrated measurements to obtain local poloidal velocity profiles. Radial resolution after inversion is 0.6-1.8 cm from the plasma edge to the center.
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
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
2008-02-29T23:59:59.000Z
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.
National Spherical Torus Experiment (NSTX) and Planned Research
Kaye, S.; Neumeyer, C.; Ono, M.; Peng, M.
1999-11-13T23:59:59.000Z
The U.S. fusion energy sciences program began in 1996 to increase emphasis on confinement concept innovation. The NSTX [1,2] is being built at PPPL as a national fusion science research facility in response to this emphasis. NSTX is to test fusion science principles of the Spherical Torus (ST) plasmas, which include: (1) High plasma pressure in low magnetic field for high fusion power density, (2) Good energy confinement is a small-size plasma, (3) Nearly fully self-driven (bootstrap) plasma current, (4) Dispersed heat and particle fluxes, and (5) Plasma startup without complicated inboard solenoid magnet. These properties of the ST plasma, if verified, would lead to possible future fusion devices of high fusion performance, small size, feasible power handling, and improved economy. The design of NSTX is depicted in Fig.1. The device is designed to study plasmas with major radius up to 85 cm, minor radius up to 68 cm, elongation up to 2, with flexibility in forming double-null, single-null, and inboard limited plasmas. The nominal operation calls for a toroidal field of 0.3 T for 5 s at the major radius, and a plasma current at 1 MA with q {approximately} 10 at edge. It features a compact center stack containing the inner legs of the toroidal field coils, a full size solenoid capable of delivering 0.6 Wb induction, inboard vacuum vessel, and composite carbon tiles. The center stack can be replaced without disturbing the main device, diagnostics, and auxiliary systems. The vessel will be covered fully with graphite tiles and can be baked to 350 C. Other wall conditioning techniques are also planned.
Engineering design of the National Spherical Torus Experiment
C. Neumeyer; P. Heitzenroeder; J. Spitzer, J. Chrzanowski; et al
2000-05-11T23:59:59.000Z
NSTX is a proof-of-principle experiment aimed at exploring the physics of the ``spherical torus'' (ST) configuration, which is predicted to exhibit more efficient magnetic confinement than conventional large aspect ratio tokamaks, amongst other advantages. The low aspect ratio (R/a, typically 1.2--2 in ST designs compared to 4--5 in conventional tokamaks) decreases the available cross sectional area through the center of the torus for toroidal and poloidal field coil conductors, vacuum vessel wall, plasma facing components, etc., thus increasing the need to deploy all components within the so-called ``center stack'' in the most efficient manner possible. Several unique design features have been developed for the NSTX center stack, and careful engineering of this region of the machine, utilizing materials up to their engineering allowables, has been key to meeting the desired objectives. The design and construction of the machine has been accomplished in a rapid and cost effective manner thanks to the availability of extensive facilities, a strong experience base from the TFTR era, and good cooperation between institutions.
Strike Point Control for the National Spherical Torus Experiment (NSTX)
Kolemen, E.; Gates, D. A.; Rowley, C. W.; Kasdin, N. J.; Kallman, J.; Gerhardt, S.; Soukhanovskii, V.; Mueller, D.
2010-07-09T23:59:59.000Z
This paper presents the first control algorithm for the inner and outer strike point position for a Spherical Torus (ST) fusion experiment and the performance analysis of the controller. A liquid lithium divertor (LLD) will be installed on NSTX which is believed to provide better pumping than lithium coatings on carbon PFCs. The shape of the plasma dictates the pumping rate of the lithium by channeling the plasma to LLD, where strike point location is the most important shape parameter. Simulations show that the density reduction depends on the proximity of strike point to LLD. Experiments were performed to study the dynamics of the strike point, design a new controller to change the location of the strike point to desired location and stabilize it. The most effective PF coils in changing inner and outer strike points were identified using equilibrium code. The PF coil inputs were changed in a step fashion between various set points and the step response of the strike point position was obtained. From the analysis of the step responses, PID controllers for the strike points were obtained and the controller was tuned experimentally for better performance. The strike controller was extended to include the outer-strike point on the inner plate to accommodate the desired low outer-strike points for the experiment with the aim of achieving "snowflake" divertor configuration in NSTX.
Edge ion heating by launched high harmonic fast waves in the National Spherical Torus Experiment
Biewer, Theodore
Edge ion heating by launched high harmonic fast waves in the National Spherical Torus Experiment T al., Fusion Technology 30, 1337 (1996)] measures the velocity distribution of ions in the plasma edge power High Harmonic Fast Wave (HHFW) rf heating in helium plasmas, with the poloidal ion temperature
Overview of Results from the National Spherical Torus Experiment (NSTX)
Gates, D; Ahn, J; Allain, J; Andre, R; Bastasz, R; Bell, M; Bell, R; Belova, E; Berkery, J; Betti, R; Bialek, J; Biewer, T; Bigelow, T; Bitter, M; Boedo, J; Bonoli, P; Bozzer, A; Brennan, D; Breslau, J; Brower, D; Bush, C; Canik, J; Caravelli, G; Carter, M; Caughman, J; Chang, C; Choe, W; Crocker, N; Darrow, D; Delgado-Aparicio, L; Diem, S; D'Ippolito, D; Domier, C; Dorland, W; Efthimion, P; Ejiri, A; Ershov, N; Evans, T; Feibush, E; Fenstermacher, M; Ferron, J; Finkenthal, M; Foley, J; Frazin, R; Fredrickson, E; Fu, G; Funaba, H; Gerhardt, S; Glasser, A; Gorelenkov, N; Grisham, L; Hahm, T; Harvey, R; Hassanein, A; Heidbrink, W; Hill, K; Hillesheim, J; Hillis, D; Hirooka, Y; Hosea, J; Hu, B; Humphreys, D; Idehara, T; Indireshkumar, K; Ishida, A; Jaeger, F; Jarboe, T; Jardin, S; Jaworski, M; Ji, H; Jung, H; Kaita, R; Kallman, J; Katsuro-Hopkins, O; Kawahata, K; Kawamori, E; Kaye, S; Kessel, C; Kim, J; Kimura, H; Kolemen, E; Krasheninnikov, S; Krstic, P; Ku, S; Kubota, S; Kugel, H; La Haye, R; Lao, L; LeBlanc, B; Lee, W; Lee, K; Leuer, J; Levinton, F; Liang, Y; Liu, D; Luhmann, N; Maingi, R; Majeski, R; Manickam, J; Mansfield, D; Maqueda, R; Mazzucato, E; McCune, D; McGeehan, B; McKee, G; Medley, S; Menard, J; Menon, M; Meyer, H; Mikkelsen, D; Miloshevsky, G; Mitarai, O; Mueller, D; Mueller, S; Munsat, T; Myra, J; Nagayama, Y; Nelson, B; Nguyen, X; Nishino, N; Nishiura, M; Nygren, R; Ono, M; Osborne, T; Pacella, D; Park, H; Park, J; Paul, S; Peebles, W; Penaflor, B; Peng, M; Phillips, C; Pigarov, A; Podesta, M; Preinhaelter, J; Ram, A; Raman, R; Rasmussen, D; Redd, A; Reimerdes, H; Rewoldt, G; Ross, P; Rowley, C; Ruskov, E; Russell, D; Ruzic, D; Ryan, P; Sabbagh, S; Schaffer, M; Schuster, E; Scott, S; Shaing, K; Sharpe, P; Shevchenko, V; Shinohara, K; Sizyuk, V; Skinner, C; Smirnov, A; Smith, D; Smith, S; Snyder, P; Soloman, W; Sontag, A; Soukhanovskii, V; Stoltzfus-Dueck, T; Stotler, D; Strait, T; Stratton, B; Stutman, D; Takahashi, R; Takase, Y; Tamura, N; Tang, X; Taylor, G; Taylor, C; Ticos, C; Tritz, K; Tsarouhas, D; Turrnbull, A; Tynan, G; Ulrickson, M; Umansky, M; Urban, J; Utergberg, E; Walker, M; Wampler, W; Wang, J; Wang, W; Weland, A
2009-01-05T23:59:59.000Z
The mission of NSTX is the demonstration of the physics basis required to extrapolate to the next steps for the spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based component test facility (ST-CTF), and to support ITER. Key issues for the ST are transport, and steady state high {beta} operation. To better understand electron transport, a new high-k scattering diagnostic was used extensively to investigate electron gyro-scale fluctuations with varying electron temperature gradient scale-length. Results from n = 3 braking studies confirm the flow shear dependence of ion transport. New results from electron Bernstein wave emission measurements from plasmas with lithium wall coating applied indicate transmission efficiencies near 70% in H-mode as a result of reduced collisionality. Improved coupling of High Harmonic Fast-Waves has been achieved by reducing the edge density relative to the critical density for surface wave coupling. In order to achieve high bootstrap fraction, future ST designs envision running at very high elongation. Plasmas have been maintained on NSTX at very low internal inductance l{sub i} {approx} 0.4 with strong shaping ({kappa} {approx} 2.7, {delta} {approx} 0.8) with {beta}{sub N} approaching the with-wall beta limit for several energy confinement times. By operating at lower collisionality in this regime, NSTX has achieved record non-inductive current drive fraction f{sub NI} {approx} 71%. Instabilities driven by super-Alfvenic ions are an important issue for all burning plasmas, including ITER. Fast ions from NBI on NSTX are super-Alfvenic. Linear TAE thresholds and appreciable fast-ion loss during multi-mode bursts are measured and these results are compared to theory. RWM/RFA feedback combined with n = 3 error field control was used on NSTX to maintain plasma rotation with {beta} above the no-wall limit. The impact of n > 1 error fields on stability is a important result for ITER. Other highlights are: results of lithium coating experiments, momentum confinement studies, scrape-off layer width scaling, demonstration of divertor heat load mitigation in strongly shaped plasmas, and coupling of CHI plasmas to OH ramp-up. These results advance the ST towards next step fusion energy devices such as NHTX and ST-CTF.
National Spherical Torus Experiment (NSTX) | Princeton Plasma Physics Lab
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Spherical torus fusion reactor
Peng, Yueng-Kay M. (Oak Ridge, TN)
1989-01-01T23:59:59.000Z
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.
Jaworski, M A; Gray, T K; Kaita, R; Kallman, J; Kugel, H; LeBlanc, B; McLean, A; Sabbagh, S A; Soukanovskii, V; Stotler, D P
2011-06-03T23:59:59.000Z
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.
Mazzucato, E.; Bell, R. E.; Ethier, S.; Hosea, J. C.; Kaye, S. M.; LeBlanc, B. P.; Lee, W. W.; Ryan, P. M.; Smith, D. R.; Wang, W. X.; Wilson, J. R.
2009-03-26T23:59:59.000Z
Various theories and numerical simulations support the conjecture that the ubiquitous problem of anomalous electron transport in tokamaks may arise from a short-scale turbulence driven by the electron temperature gradient. To check whether this turbulence is present in plasmas of the National Spherical Torus Experiment (NSTX), measurements of turbulent fluctuations were performed with coherent scattering of electromagnetic waves. Results from plasmas heated by high harmonic fast waves (HHFW) show the existence of density fluctuations in the range of wave numbers k??e=0.1-0.4, corresponding to a turbulence scale length of the order of the collisionless skin depth. Experimental observations and agreement with numerical results from the linear gyro-kinetic GS2 code indicate that the observed turbulence is driven by the electron temperature gradient. These turbulent fluctuations were not observed at the location of an internal transport barrier driven by a negative magnetic shear.
Fast ion absorption of the high harmonic fast wave in the National Spherical Torus Experiment a...
Egedal, Jan
the high harmonic fast wave #HHFW# and energetic particles in a spherical torus #ST# #Ref. 1# is a new, Princeton, New Jersey 08543 R. W. Harvey CompX, Del Mar, California 92014 T. K. Mau University of California, Columbia University, New York, New York 10027 J. Egedal Plasma Science and Fusion Center, Massachusetts
Direct X-B mode conversion for high-? national spherical torus experiment in nonlinear regime
Ali Asgarian, M., E-mail: maliasgarian@ph.iut.ac.ir, E-mail: maa@msu.edu [Physics Department, Isfahan University of Technology, Isfahan 84156 (Iran, Islamic Republic of); Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824-1226 (United States); Parvazian, A.; Abbasi, M. [Physics Department, Isfahan University of Technology, Isfahan 84156 (Iran, Islamic Republic of); Verboncoeur, J. P. [Department of Electrical and Computer Engineering, Michigan State University, Michigan 48824-1226 (United States)
2014-09-15T23:59:59.000Z
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.
Dynamical Evolution of Pedestal Parameters in ELMy H-mode in the National Spherical Torus Experiment
Diallo, A; Kubota, S; Sontag, A; Osborne, T; Podesta, M; Bell, R E; LeBlanc, B P; Menard, J
2011-07-27T23:59:59.000Z
Characterizations of the pedestal parameter dynamics throughout the edge localized modes(ELM) cycles are performed on the National Spherical Torus Experiment (NSTX, [M. Ono et al., Nucl. Fusion 40, 557 (2000)]). A clear buildup of the pedestal height is observed between ELMs for three di erent plasma currents, which tends to saturate prior to the onset of ELM at low and medium plasma current. Similarly, the pedestal width increases with no clear evidence of saturation during an ELM cycle. The maximum pedestal gradient increases as a function of plasma current, reaches a nominal value after the ELM crash, and remains constant until the end of the ELM cycle. The pedestal height just prior to the onset of ELM is shown to increase quadratically with plasma current. The pedestal width ? is proportional to the square-root of the poloidal ? at the top of the pedestal. Coherent density uctuations strongly increasing at the plasma edge are observed to be maximum after the ELM crash and to decay during the rest of the ELM cycle. Finally, the pedestal parameters evolution during the ELM cycle as well as the scaling with Ip of the pedestal pressure prior to the onset ELM are found to be qualitatively consistent with the peeling ballooning theory.
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.
2011-01-01T23:59:59.000Z
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
A Megawatt-level 28z GHz Heating System For The National Spherical Torus Experiment Upgrade
Taylor, Gary
2014-04-01T23:59:59.000Z
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.
R.J. Maqueda, D.P. Stotler and the NSTX Team.
2010-05-19T23:59:59.000Z
While intermittent filamentary structures, also known as blobs, are routinely seen in the low-field-side scrape-off layer of the National Spherical Torus Experiment (NSTX) (Ono et al 2000 Nucl. Fusion 40 557), fine structured filaments are also seen on the lower divertor target plates of NSTX. These filaments, not associated with edge localized modes, correspond to the interaction of the turbulent blobs seen near the midplane with the divertor plasma facing components. The fluctuation level of the neutral lithium light observed at the divertor, and the skewness and kurtosis of its probability distribution function, is similar to that of midplane blobs seen in D?; e.g. increasing with increasing radii outside the outer strike point (OSP) (separatrix). In addition, their toroidal and radial movement agrees with the typical movement of midplane blobs. Furthermore, with the appropriate magnetic topology, i.e. mapping between the portion of the target plates being observed into the field of view of the midplane gas puff imaging diagnostic, very good correlation is observed between the blobs and the divertor filaments. The correlation between divertor plate filaments and midplane blobs is lost close to the OSP. This latter observation is consistent with the existence of ‘magnetic shear disconnection’ due to the lower X-point, as proposed by Cohen and Ryutov (1997 Nucl. Fusion 37 621).
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Gerhardt, S. P. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States); Fredrickson, E. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States); Guttadora, L. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States); Kaita, R. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States); Kugel, H. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States); Menard, J. [Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States); Takahashi, H. [Princeton Fusion Research LLC, Princeton, NJ (United States)
2011-10-06T23:59:59.000Z
This paper describes techniques for measuring halo currents, and their associated toroidal peaking, in the National Spherical Torus Experiments [M. Ono, et. al, Nuclear Fusion 40, 557 (2000)]. 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 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 is shown.
Spherical torus fusion reactor
Martin Peng, Y.K.M.
1985-10-03T23:59:59.000Z
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.
M.G. Bell, H.W. Kugel, R. Kaita, L.E. Zakharov, H. Schneider, B.P. LeBlanc, D. Mansfield, R.E. Bell, R. Maingi, S. Ding, S.M. Kaye, S.F. Paul, S.P. Gerhardt, J.M. Canik, J.C. Hosea, G. Taylor and the NSTX Research Team
2009-08-20T23:59:59.000Z
Experiments in the National Spherical Torus Experiment (NSTX) have shown beneficial effects on the performance of divertor plasmas as a result of applying lithium coatings on the graphite and carbonfiber- composite plasma-facing components. These coatings have mostly been applied by a pair of lithium evaporators mounted at the top of the vacuum vessel which inject collimated streams of lithium vapor towards the lower divertor. In NBI-heated, deuterium H-mode plasmas run immediately after the application of lithium, performance modifications included decreases in the plasma density, particularly in the edge, and inductive flux consumption, and increases in the electron and ion temperatures and the energy confinement time. Reductions in the number and amplitude of ELMs were observed, including complete ELM suppression for periods up to 1.2 s, apparently as a result of altering the stability of the edge. However, in the plasmas where ELMs were suppressed, there was a significant secular increase in the effective ion charge Zeff and the radiated power as a result of increases in the carbon and medium-Z metallic impurities, although not of lithium itself which remained at a very low level in the plasma core, <0.1%. The impurity buildup could be inhibited by repetitively triggering ELMs with the application of brief pulses of an n = 3 radial field perturbation. The reduction in the edge density by lithium also inhibited parasitic losses through the scrape-off layer of ICRF power coupled to the plasma, enabling the waves to heat electrons in the core of H-mode plasmas produced by NBI. Lithium has also been introduced by injecting a stream of chemically stabilized, fine lithium powder directly into the scrape-off layer of NBI-heated plasmas. The lithium was ionized in the SOL and appeared to flow along the magnetic field to the divertor plates. This method of coating produced similar effects to the evaporated lithium but at lower amounts.
C.E. Bush; M.G. Bell; R.E. Bell; J. Boedo; E.D. Fredrickson; S.M. Kaye; S. Kubota; B.P. LeBlanc; R. Maingi; R.J. Maqueda; S.A. Sabbagh; V.A. Soukhanovskii; D. Stutman; D.W. Swain; J.B. Wilgen; S.J. Zweben; W.M. Davis; D.A. Gates; D.W. Johnson; R. Kaita; H.W. Kugel; D. Mastrovito; S. Medley; J.E. Menard; D. Mueller; M. Ono; F. Paoletti; S.J. Paul; Y-K.M. Peng; R. Raman; P.G. Roney; A.L. Roquemore; C.H. Skinner; E.J. Synakowski; G. Taylor; the NSTX Team
2003-01-09T23:59:59.000Z
Edge parameters play a critical role in H-mode (high-confinement mode) access, which is a key component of plasma discharge optimization in present-day toroidal confinement experiments and the design of next-generation devices. Because the edge magnetic topology of a spherical torus (ST) differs from a conventional aspect ratio tokamak, H-modes in STs exhibit important differences compared with tokamaks. The dependence of the NSTX (National Spherical Torus Experiment) edge plasma on heating power, including the L-H transition requirements and the occurrence of edge-localized modes (ELMs), and on divertor configuration is quantified. Comparisons between good L-modes (low-confinement modes) and H-modes show greater differences in the ion channel than the electron channel. The threshold power for the H-mode transition in NSTX is generally above the predictions of a recent ITER (International Thermonuclear Experimental Reactor) scaling. Correlations of transition and ELM phenomena with turbulent fluctuations revealed by Gas Puff Imaging (GPI) and reflectometry are observed. In both single-null and double-null divertor discharges, the density peaks off-axis, sometimes developing prominent ''ears'' which can be sustained for many energy confinement times, tau subscript ''E'', in the absence of ELMs. A wide variety of ELM behavior is observed, and ELM characteristics depend on configuration and fueling.
Recent Progress on Spherical Torus Research
Ono, Masayuki [PPPL; Kaita, Robert [PPPL
2014-01-01T23:59:59.000Z
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.
G. Taylor; P.C. Efthimion; B.P. LeBlanc; M.D. Carter; J.B. Caughman; J.B. Wilgen; J. Preinhaelter; R.W. Harvey; S.A. Sabbagh
2005-02-02T23:59:59.000Z
Efficient coupling of thermal electron Bernstein waves (EBW) to ordinary mode (Omode) electromagnetic radiation has been measured in plasmas heated by energetic neutral beams and high harmonic fast waves in the National Spherical Torus Experiment (NSTX) [M. Ono, S. Kaye, M. Peng, et al., Proceedings 17th IAEA Fusion Energy Conference (IAEA, Vienna, Austria, 1999), Vol.3, p. 1135]. The EBW to electromagnetic mode coupling efficiency was measured to be 0.8 {+-} 0.2, compared to a numerical EBW modeling prediction of 0.65. The observation of efficient EBW coupling to O-mode, in relatively good agreement with numerical modeling, is a necessary prerequisite for implementing a proposed high power EBW current drive system on NSTX.
Podesta, M; Fredrickson, E D; Gorelenkov, N N; LeBlanc, B P; Heidbrink, W W; Crocker, N A; Kubota, S
2010-08-19T23:59:59.000Z
The effects of a sheared toroidal rotation on the dynamics of bursting Toroidicity-induced Alfven eigenmodes are investigated in neutral beam heated plasmas on the National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40 557 (2000)]. The modes have a global character, extending over most of the minor radius. A toroidal rotation shear layer is measured at the location of maximum drive for the modes. Contrary to results from other devices, no clear evidence of increased damping is found. Instead, experiments with simultaneous neutral beam and radio-frequency auxiliary heating show a strong correlation between the dynamics of the modes and the instability drive. It is argued that kinetic effects involving changes in the mode drive and damping mechanisms other than rotation shear, such as continuum damping, are mostly responsible for the bursting dynamics of the modes.
S.S. Medley; D.S. Darrow; A.L. Roquemore
2005-06-15T23:59:59.000Z
A change in the response of the neutron detectors on the National Spherical Torus Experiment occurred between the 2002-2003 and 2004 experimental run periods. An analysis of this behavior by investigating the neutron diagnostic operating conditions and comparing measured and TRANSP-calculated neutron rates is presented. Also a revised procedure for cross calibration of the neutron scintillator detectors with the fission chamber detectors was implemented that delivers good agreement amongst the measured neutron rates for all neutron detectors and all run periods. For L-mode discharges, the measured and TRANSP-calculated neutron rates now match closely for all run years. For H-mode discharges over the entire 2002-2004 period, the 2FG scintillator and fission chamber measurements match each other but imply a neutron deficit of 11.5% relative to the TRANSP-calculated neutron. The results of this report impose a modification on all of the previously used calibration factors for the entire neutron detector suite over the 2002-2004 period. A tabular summary of the new calibration factors is provided including certified calibration factors for the 2005 run.
Kaye, S. M., E-mail: skaye@pppl.gov; Guttenfelder, W.; Bell, R. E.; Gerhardt, S. P.; LeBlanc, B. P.; Maingi, R. [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)
2014-08-15T23:59:59.000Z
A representative H-mode discharge from the National Spherical Torus eXperiment is studied in detail to utilize it as a basis for a time-evolving prediction of the electron temperature profile using an appropriate reduced transport model. The time evolution of characteristic plasma variables such as ?{sub e},??{sub e}{sup ?}, the MHD ? parameter, and the gradient scale lengths of T{sub e}, T{sub i}, and n{sub e} were examined as a prelude to performing linear gyrokinetic calculations to determine the fastest growing micro instability at various times and locations throughout the discharge. The inferences from the parameter evolutions and the linear stability calculations were consistent. Early in the discharge, when ?{sub e} and ?{sub e}{sup ?} were relatively low, ballooning parity modes were dominant. As time progressed and both ?{sub e} and ?{sub e}{sup ?} increased, microtearing became the dominant low-k{sub ?} mode, especially in the outer half of the plasma. There are instances in time and radius, however, where other modes, at higher-k{sub ?}, may, in addition to microtearing, be important for driving electron transport. Given these results, the Rebut-Lallia-Watkins (RLW) electron thermal diffusivity model, which is based on microtearing-induced transport, was used to predict the time-evolving electron temperature across most of the profile. The results indicate that RLW does a good job of predicting T{sub e} for times and locations where microtearing was determined to be important, but not as well when microtearing was predicted to be stable or subdominant.
Soukhanovskii, V A; Maingi, R; Gates, D; Menard, J; Paul, S F; Raman, R; Roquemore, A L; Bell, R E; Bush, C; Kaita, R
2008-09-22T23:59:59.000Z
Experiments conducted in high-performance 1.0-1.2 MA 6 MW NBI-heated H-mode plasmas with a high flux expansion radiative divertor in NSTX demonstrate that significant divertor peak heat flux reduction and access to detachment may be facilitated naturally in a highly-shaped spherical torus (ST) configuration. Improved plasma performance with high {beta}{sub p} = 15-25%, a high bootstrap current fraction f{sub BS} = 45-50%, longer plasma pulses, and an H-mode regime with smaller ELMs has been achieved in the lower single null configuration with higher-end elongation 2.2-2.4 and triangularity 0.6-0.8. Divertor peak heat fluxes were reduced from 6-12 MW/m{sup 2} to 0.5-2 MW/m{sup 2} in ELMy H-mode discharges using high magnetic flux expansion and partial detachment of the outer strike point at several D{sub 2} injection rates, while good core confinement and pedestal characteristics were maintained. The partially detached divertor regime was characterized by a 30-60% increase in divertor plasma radiation, a peak heat flux reduction by up to 70%, measured in a 10 cm radial zone, a five-fold increase in divertor neutral pressure, and a significant volume recombination rate increase.
Soukhanovskii, V A; Maingi, R; Gates, D; Menard, J
2008-12-31T23:59:59.000Z
Experiments conducted in high-performance 1.0 MA and 1.2 MA 6 MW NBI-heated H-mode discharges with a high magnetic flux expansion radiative divertor in NSTX demonstrate that significant divertor peak heat flux reduction and access to detachment may be facilitated naturally in a highly-shaped spherical torus (ST) configuration. Improved plasma performance with high {beta}{sub t} = 15-25%, a high bootstrap current fraction f{sub BS} = 45-50%, longer plasma pulses, and an H-mode regime with smaller ELMs has been achieved in the strongly-shaped lower single null configuration with elongation {kappa} = 2.2-2.4 and triangularity {delta} = 0.6-0.8. Divertor peak heat fluxes were reduced from 6-12 MW/m{sup 2} to 0.5-2 MW/m{sup 2} in ELMy H-mode discharges using the inherently high magnetic flux expansion f{sub m} = 16-25 and the partial detachment of the outer strike point at several D{sub 2} injection rates. A good core confinement and pedestal characteristics were maintained, while the core carbon concentration and the associated Z{sub eff} were reduced. The partially detached divertor regime was characterized by an increase in divertor radiated power, a reduction of ion flux to the plate, and a large neutral compression ratio. Spectroscopic measurements indicated a formation of a high-density, low temperature region adjacent to the outer strike point, where substantial increases in the volume recombination rate and CII, CIII emission rates was measured.
R.J. Maqueda, D.P. Stotler, S.J. Zweben, and the NSTX Team
2010-11-22T23:59:59.000Z
A gas puff imaging diagnostic is used in the National Spherical Tokamak Experiment [M. Ono, et al., Nucl. Fusion 40, 557 (2000)] to study the edge turbulence and intermittency present during H-mode discharges. In the case of low power Ohmic H-modes the suppression of turbulence/blobs is maintained through the duration of the (short lived) H-modes. Similar quiescent edges are seen during the early stages of H-modes created with the use of neutral beam injection. Nevertheless, as time progresses following the L-H transition, turbulence and blobs reappear although at a lower level than that typically seen during L-mode confinement. It is also seen that the time-averaged SOL emission profile broadens, as the power loss across the separatrix increases. These broad profiles are characterized by a large level of fluctuations and intermittent events.
A feasibility study for the spherical torus experiment
Lazarus, E [Oak Ridge National Laboratory (ORNL); Peng, Yueng Kay Martin [ORNL
1985-10-01T23:59:59.000Z
Oak Ridge National Laboratory (ORNL) proposes to build the Spherical Torus Experiment (STX), a very low aspect ratio toroidal confinement device. This proposal concentrates on tokamak operation of the experiment; however, it can in principle be operated as a pinch or reversed-field pinch as well. As a tokamak, the spherical torus confines a plasma that is characterized by high toroidal beta, low poloidal beta, large natural elongation, high plasma current for a given edge q, and strong paramagnetism. These features combine to offer the possibility of a compact, low-field fusion device. The figure below shows that when compared to a conventional tokamak the spherical torus represents a major change in geometry. The primary goals of the experiment will be to demonstrate a capability for high beta (20%) in the first stability regime, to extend our knowledge of tokamak confinement scaling, and to test oscillating-field current drive. The experiment will operate in the high-beta, collisionless regime, which is achieved in STX at low temperatures because of the geometry. At a minimum, operation of STX will help to resolve fundamental questions regarding the scaling of beta and confinement in tokamaks. Complete success in this program would have a significant impact on toroidal fusion research in that it would demonstrate solutions to the problems of beta and steady-state operation in the tokamak. The proposed device has a major radius of 0.45 m, a toroidai field of 0.5 T, a plasma current of 900 kA, and heating by neutral beam injection. We estimate 30 months for design, construction, and assembly. The budget estimate, including contingency and escalation, is $6.8 million.
Princeton Plasma Physics Laboratory
Demonstration of Tokamak Ohmic Flux Saving by Transient Coaxial Helicity Injection in the National: 52.55.Fa, 52.25.Vy, 52.35.Vd, 52.50.Nr Toroidal magnetic configurations based on the tokamak concept component in conventional tokamak reactor designs could be elimi- nated [1,2]. The central solenoid also
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.
2011-01-10T23:59:59.000Z
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 inmore »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.« 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)
2011-01-10T23:59:59.000Z
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.
NATIONAL SPHERICAL TORUS CENTER STACK
Princeton Plasma Physics Laboratory
.................................. 2.4 Shear/Compression Tests ................................ INSULATION ELECTRICAL TESTS Conductor ............ 24 7.6 Winding Tension vs. Insulation Compression ......... 26 8.0 CONCLUSIONS SHEAR TESTS . . . 111 #12;INDEX OF TABLES 2-l 2-2 2-3 2-4 2-5 2-6 2-7 3-8 3-9 4-10 4-11 5-12 5-13 5-14 5
Modeling of Spherical Torus Plasmas for Liquid Lithium Wall Experiments
R. Kaita; S. Jardin; B. Jones; C. Kessel; R. Majeski; J. Spaleta; R. Woolley; L. Zakharo; B. Nelson; M. Ulrickson
2002-01-29T23:59:59.000Z
Liquid metal walls have the potential to solve first-wall problems for fusion reactors, such as heat load and erosion of dry walls, neutron damage and activation, and tritium inventory and breeding. In the near term, such walls can serve as the basis for schemes to stabilize magnetohydrodynamic (MHD) modes. Furthermore, the low recycling characteristics of lithium walls can be used for particle control. Liquid lithium experiments have already begun in the Current Drive eXperiment-Upgrade (CDX-U). Plasmas limited with a toroidally localized limiter have been investigated, and experiments with a fully toroidal lithium limiter are in progress. A liquid surface module (LSM) has been proposed for the National Spherical Torus Experiment (NSTX). In this larger ST, plasma currents are in excess of 1 MA and a typical discharge radius is about 68 cm. The primary motivation for the LSM is particle control, and options for mounting it on the horizontal midplane or in the divertor region are under consideration. A key consideration is the magnitude of the eddy currents at the location of a liquid lithium surface. During plasma start up and disruptions, the force due to such currents and the magnetic field can force a conducting liquid off of the surface behind it. The Tokamak Simulation Code (TSC) has been used to estimate the magnitude of this effect. This program is a two dimensional, time dependent, free boundary simulation code that solves the MHD equations for an axisymmetric toroidal plasma. From calculations that match actual ST equilibria, the eddy current densities can be determined at the locations of the liquid lithium. Initial results have shown that the effects could be significant, and ways of explicitly treating toroidally local structures are under investigation.
Spherical Torus Plasma Interactions with Large-Area Liquid Lithium Surfaces in CDX-U
California at Los Angeles, University of
- 1 - Spherical Torus Plasma Interactions with Large-Area Liquid Lithium Surfaces in CDX-U R. KAITA of this concept, key liquid lithium-plasma interaction questions are being addressed in the CDX-U device[2 (PPPL) is a spherical torus (ST) dedicated to the exploration of liquid lithium as a potential solution
S. S. Medley, N. N. Gorelenkov, R. E. Bell, E. D. Fredrickson, S. P. Gerhardt, B. P. LeBlanc, M. Podestà, A. L. Roquemore, and the NSTX Team
2010-06-09T23:59:59.000Z
An increase of up to four-fold in the E||B Neutral Particle Analyzer (NPA) charge exchange neutral flux localized at the Neutral Beam (NB) injection full energy is observed in the National Spherical Torus Experiment (NSTX). Termed the High-Energy Feature (HEF), it appears on the NB-injected energetic ion spectrum only in discharges where tearing or kink-type modes (f < 10 kHz) are absent, TAE activity (f ~ 10-150 kHz) is weak (?Brms < 75 mGauss) and CAE/GAE activity (f ~ 400 – 1200 kHz) is robust. The feature exhibits a growth time of ~ 20 - 80 ms and occasionally develops a slowing down distribution that continues to evolve over periods of 100?s of milliseconds, a time scale long compared with the typical ~ 10?s ms equilibration time of the NB injected particles. The HEF is observed only in H-mode (not L-mode) discharges with injected NB power of 4 MW or greater and in the field pitch range v||/v ~ 0.7 – 0.9; i.e. only for passing (never trapped) energetic ions. The HEF is suppressed by vessel conditioning using lithium deposition at rates ~ 100 mg/shot, a level sufficient to suppress ELM activity. Increases of ~ 10 - 30 % in the measured neutron yield and total stored energy are observed to coincide with the feature along with broadening of measured Te(r), Ti(r) and ne(r) profiles. However, TRANSP analysis shows that such increases are driven by plasma profile changes and not the HEF phenomenon itself. Though a definitive mechanism has yet to be developed, the HEF appears to be caused by a form of TAE/CAE wave-particle interaction that distorts of the NB fast ion distribution in phase space.
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
Supported by National Spherical Torus Experiment
-Materials Interactions, Advanced Physics, Nuclear Component Testing Burning Plasma Physics ST offers compact geometry / ITER Operations Passive plates Blanket modules Port Control Coils Control Coils ITER vessel ITER plasma
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
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
Advanced tokamak reactors based on the spherical torus (ATR/ST). Preliminary design considerations
Miller, R.L.; Krakowski, R.A.; Bathke, C.G.; Copenhaver, C.; Schnurr, N.M.; Engelhardt, A.G.; Seed, T.J.; Zubrin, R.M.
1986-06-01T23:59:59.000Z
Preliminary design results relating to an advanced magnetic fusion reactor concept based on the high-beta, low-aspect-ratio, spherical-torus tokamak are summarized. The concept includes resistive (demountable) toroidal-field coils, magnetic-divertor impurity control, oscillating-field current drive, and a flowing liquid-metal breeding blanket. Results of parametric tradeoff studies, plasma engineering modeling, fusion-power-core mechanical design, neutronics analyses, and blanket thermalhydraulics studies are described. The approach, models, and interim results described here provide a basis for a more detailed design. Key issues quantified for the spherical-torus reactor center on the need for an efficient drive for this high-current (approx.40 MA) device as well as the economic desirability to increase the net electrical power from the nominal 500-MWe(net) value adopted for the baseline system. Although a direct extension of present tokamak scaling, the stablity and transport of this high-beta (approx.0.3) plasma is a key unknown that is resoluble only by experiment. The spherical torus generally provides a route to improved tokamak reactors as measured by considerably simplified coil technology in a configuration that allows a realistic magnetic divertor design, both leading to increased mass power density and reduced cost.
First Observation Of ELM Pacing With Vertical Jogs In A Spherical Torus
Gerhardt, S P; Canik, J M; Maingi, R; Bell, R; Gates, d; Goldston, R; Hawryluk, R; Le Blanc, B P; Menard, J; Sontag, A C; Sabbagh, S
2010-07-15T23:59:59.000Z
Experiments in a number of conventional aspect ratio tokamaks have been successful in pacing edge localized modes (ELMs) by rapid vertical jogging of the plasma. This paper demonstrates the first pacing of ELMs in a spherical torus plasma. Applied 30 Hz vertical jogs synchronized the ELMs with the upward motion of the plasma. 45 Hz jogs also lead to an increase in the ELM frequency, though the synchronization of the ELMs and jogs was unclear. A reduction in the ELM energy was observed at the higher driven ELM frequencies. __________________________________________________
Berkery, J. W.; Sabbagh, S. A.; Balbaky, A. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)] [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States); Bell, R. E.; Diallo, A.; Gerhardt, S. P.; LeBlanc, B. P.; Manickam, J.; Menard, J. E.; Podestà, M. [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Betti, R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)] [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)
2014-05-15T23:59:59.000Z
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.
Surface Treatment of a Lithium Limiter for Spherical Torus Plasma Experiments
Kaita, R.; Majeski, R.; Doerner, R.; Antar, G.; Timberlake, J.; Spaleta, J.; Hoffman, D.; Jones, B.; Munsat, T.; Kugel, H.; Taylor, G.; Stutman, D.; Soukhanovskii, V.; Maingi, R.; Molesa, S.; Efthimion, P.; Menard, J.; Finkenthal, M.; Luckhardt, S.
2001-03-20T23:59:59.000Z
The concept of a flowing lithium first wall for a fusion reactor may lead to a significant advance in reactor design, since it could virtually eliminate the concerns with power density and erosion, tritium retention, and cooling associated with solid walls. As part of investigations to determine the feasibility of this approach, plasma interaction questions in a toroidal plasma geometry are being addressed in the Current Drive eXperiment-Upgrade (CDX-U) spherical torus (ST). The first experiments involved a toroidally local lithium limiter (L3). Measurements of pumpout rates indicated that deuterium pumping was greater for the L3 compared to conventional boron carbide limiters. The difference in the pumpout rates between the two limiter types decreased with plasma exposure, but argon glow discharge cleaning was able to restore the pumping effectiveness of the L3. At no point, however, was the extremely low recycling regime reported in previous lithium experiments achieved. This may be due to the much larger lithium surfaces that were exposed to the plasma in the earlier work. The possibility will be studied in the next set of CDX-U experiments, which are to be conducted with a large area, fully toroidal lithium limiter.
Spherical Torus Plasma Interactions with Large-area Liquid Lithium Surfaces in CDX-U
R. Kaita; R. Majeski; M. Boaz; P. Efthimion; B. Jones; D. Hoffman; H. Kugel; J. Menard; T. Munsat; A. Post-Zwicker; V. Soukhanovskii; J. Spaleta; G. Taylor; J. Timberlake; R. Woolley; L. Zakharov; M. Finkenthal; D. Stutman; G. Antar; R. Doerner; S. Luckhardt; R. Maingi; M. Maiorano; S. Smith
2002-01-18T23:59:59.000Z
The Current Drive Experiment-Upgrade (CDX-U) device at the Princeton Plasma Physics Laboratory (PPPL) is a spherical torus (ST) dedicated to the exploration of liquid lithium as a potential solution to reactor first-wall problems such as heat load and erosion, neutron damage and activation, and tritium inventory and breeding. Initial lithium limiter experiments were conducted with a toroidally-local liquid lithium rail limiter (L3) from the University of California at San Diego. Spectroscopic measurements showed a clear reduction of impurities in plasmas with the L3, compared to discharges with a boron carbide limiter. The evidence for a reduction in recycling was less apparent, however. This may be attributable to the relatively small area in contact with the plasma, and the presence of high-recycling surfaces elsewhere in the vacuum chamber. This conclusion was tested in subsequent experiments with a fully toroidal lithium limiter that was installed above the floor of the vacuum vessel. The new limiter covered over ten times the area of the L3 facing the plasma. Experiments with the toroidal lithium limiter have recently begun. This paper describes the conditioning required to prepare the lithium surface for plasma operations, and effect of the toroidal liquid lithium limiter on discharge performance.
National Spherical Torus Experiment Upgrade Status and Plans*
ANS 20th Topical Meeting on the Technology of Fusion Energy (TOFE-2012) Nashville, TN USA August 27 confinement physics predictive capability for ITER and beyond · Develop ST as fusion energy system Lithium fusion nuclear environment of copious neutrons to develop an experimental database on: Nuclear
National Spherical Torus Experiment (NSTX) Construction, Commissioning, and Initial Operations
supplies, and RF sources, cooling water systems, etc., is made to minimize the overall cost 350 C PFCs, 150C VV PROGRESS AND ACCOMPLISHMENTS Tremendous progress was made during the past year
National Spherical Torus Experiment (NSTX) Construction, Commissioning, and Initial Operations
magnet power supplies, and RF sources, cooling water systems, etc., is made to minimize the overall cost 350 C PFCs, 150C VV PROGRESS AND ACCOMPLISHMENTS Tremendous progress was made during the past year
National Spherical Torus Experiment (NSTX) Center Stack Upgrade
Neumeyer, C; Chrzanowski, J; Dudek, L; Fan, H; Hatcher, R; Heitzenroeder, P; Menard, J; Ono, M; Ramakrishnan, S; Titus, P; Woolley, R
2009-09-24T23:59:59.000Z
The purpose of the NSTX Center Stack Upgrade project is to expand the NSTX operational space and thereby the physics basis for next-step ST facilities. The plasma aspect ratio (ratio of plasma major to minor radius) of the upgrade is increased to 1.5 from the original value of 1.26, which increases the cross sectional area of the center stack by a factor of ~ 3 and makes possible higher levels of performance and pulse duration.
National Spherical Torus Experiment (NSTX) Center Stack Upgrade
Princeton Plasma Physics Laboratory
) coil surrounded by an ohmic heating (OH) solenoid and a several poloidal field (PF) shaping coils, all
National Spherical Torus Experiment-Upgrade SAFETY ASSESSMENT DOCUMENT
Princeton Plasma Physics Laboratory
-00 Revision 6 DECEMBER 2014 Prepared by: _______________________ Jerry Levine Head, PPPL ESH&S Reviewed by Chair, PPPL ES&H Executive Board #12;#12;NSTX-U SAFETY ASSESSMENT DOCUMENT (SAD) Table of Contents 1
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
Choe, Kyumin; Jung, Bongki [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)] [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Chung, Kyoung-Jae, E-mail: jkjlsh1@snu.ac.kr [Center for Advance Research in Fusion Reactor Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)] [Center for Advance Research in Fusion Reactor Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Hwang, Y. S. [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of) [Department of Nuclear Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Center for Advance Research in Fusion Reactor Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)
2014-02-15T23:59:59.000Z
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.
in an underestimation of its cost and a more prolonged construction process. An 18-month series of project reviews spherical torus program Page 1 of 2http://www.princeton.edu/main/news/archive/S21/15/04A97/index://www.pppl.gov/> (PPPL) will phase out construction of the National Compact Stellarator Experiment (NCSX) and instead
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
2012-09-26T23:59:59.000Z
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.
Scientific Opportunities and Challenges in the Upgraded National Spherical
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Abdou, Mohamed Fusion nuclear technology, VNS UCLA Gates, Dave NSTX plasma experimentation PPPL Hegna 100 IEA ST Agreement, FPCC, 2/27-28/07 3 Tritium self-sufficiency goal (%) ~0 ~100 100 # Abdou et al
Vessel Eddy Current Measurement for the National Spherical Torus Experiment (NSTX)
D.A. Gates; J. Menard; R. Marsala
2004-11-19T23:59:59.000Z
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.
Closeout Report for theCloseout Report for the National Spherical Torus
Princeton Plasma Physics Laboratory
in recommendations to improve techniques for soldering cooling tubes in the TF conductor to prevent flux from techniques (e.
Advances in High-harmonic Fast Wave Physics in the National Spherical Torus Experiment
Taylor, G; Hosea, J C; LeBlanc, B P; Phillips, C K; Podesta, M; Valeo, E J; Wilson, J R; Ahn, J -W; Chen, G; Green, D L; Jaeger, E F; Maingi, R; Ryan, P M; Wilgen, J B; Heidbrink, W W; Liu, D; Bonoli, P T; Brecht, T; Choi, M
2009-12-01T23:59:59.000Z
Improved core high-harmonic fast wave (HHFW) heating at longer wavelengths and during start-up and plasma current ramp-up, has now been obtained by lowering the edge density with lithium wall conditioning, thereby moving the critical density for perpendicular fast-wave propagation away from the vessel wall. Lithium conditioning allowed significant HHFW core electron heating of deuterium neutral beam injection (NBI) fuelled H-mode plasmas to be observed for the first time. Large edge localized modes were observed immediately after the termination of rf power. Visible and infrared camera images show that fast wave interactions can deposit considerable rf energy on the outboard divertor. HHFW-generated parametric decay instabilities were observed to heat ions in the plasma edge and may be the cause for a measured drag on edge toroidal rotation during HHFW heating. A significant enhancement in neutron rate and fast-ion profile were measured in NBI-fuelled plasmas when HHFW heating was applied. __________________________________________________
Physics Design Requirements for the National Spherical Torus Experiment Liquid Lithium Divertor
Kugel, W.; Bell, M.; Berzak,L.; Brooks, A.; Ellis, R.; Gerhardt, S.; Harjes, H.; Kaita, R.; Kallman, J.; Maingi, R.; Majeski, R.; Mansfield, D.; Menard, J.; Nygren,R. E.; Soukhanovskii, V.; Stotler, D.; Wakeland, P.; Zakharov L. E.
2008-09-26T23:59:59.000Z
Recent NSTX high power divertor experiments have shown significant and recurring benefits of solid lithium coatings on PFC's to the performance of divertor plasmas in both L- and H- mode confinement regimes heated by high-power neutral beams. The next step in this work is installation of a liquid lithium divertor (LLD) to achieve density control for inductionless current drive capability (e.g., about a 15-25% ne decrease from present highest non-inductionless fraction discharges which often evolve toward the density limit, ne/nGW~1), to enable ne scan capability (x2) in the H-mode, to test the ability to operate at significantly lower density for future ST-CTF reactor designs (e.g., ne/nGW = 0.25), and eventually to investigate high heat-flux power handling (10 MW/m2) with longpulse discharges (>1.5s). The first step (LLD-1) physics design encompasses the desired plasma requirements, the experimental capabilities and conditions, power handling, radial location, pumping capability, operating temperature, lithium filling, MHD forces, and diagnostics for control and characterization.
Fast ion absorption of the high harmonic fast wave in the National Spherical Torus Experimenta...
Egedal, Jan
, Princeton, New Jersey 08543 R. W. Harvey CompX, Del Mar, California 92014 T. K. Mau University of California, Columbia University, New York, New York 10027 J. Egedal Plasma Science and Fusion Center, Massachusetts on Energetic Particles in Magnetic Confinement Systems, 2000, p. 109 and CONBEAM J. Egedal et al., Phys
Parametric Dependence Of Fast-ion Transport Events On The National Spherical Torus Experiment
Fredrickson, Erik; Gorelenkov, N. N.; Podesta, M.; Gerhardt, S. P.; Bell, R. E.; Diallo, A.; LeBlanc, B. [Princeton Plasma Physics Lab., NJ (United States)] [Princeton Plasma Physics Lab., NJ (United States); Bortolon, A. [Univ. of Tennessee, Knoxville, TN (United States)] [Univ. of Tennessee, Knoxville, TN (United States)
2014-03-31T23:59:59.000Z
Neutral-beam heated tokamak plasmas commonly have more than one third of the plasma kinetic energy in the non-thermal energetic beam ion population. This population of fast ions heats the plasma, provides some of the current drive, and can affect the stability (positively or negatively) of magnetohydrodynamic instabilities. This population of energetic ions is not in thermodynamic equilibrium, thus there is free-energy available to drive instabilities, which may lead to redistribution of the fast ion population. Understanding under what conditions beam-driven instabilities arise, and the extent of the resulting perturbation to the fast ion population, is important for predicting and eventually demonstrating non-inductive current ramp-up and sustainment in NSTX-U, as well as the performance of future fusion plasma experiments such as ITER. This paper presents an empirical approach towards characterizing the stability boundaries for some common energetic-ion-driven instabilities seen on NSTX.
Confinement and Local Transport in the National Spherical Torus Experiment NSTX
Kaye, S M; Stutman, D; Tritz, K; Yuh, H; Bell, M G; Bell, R E; Domier, C W; Gates, D; Horton, W; Kim, J; LeBlanc, B P; Luhmann Jr, N C; Maingi, R; Mazzucato, E; Menard, J E; Mikkelsen, D; Mueller, D; Park, H; Rewoldt, G; Sabbagh, S A; Smith, D R
2007-03-15T23:59:59.000Z
NSTX operates at low aspect ratio (R/a~1.3) and high beta (up to 40%), allowing tests of global confinement and local transport properties that have been established from higher aspect ratio devices. NSTX plasmas are heated by up to 7 MW of deuterium neutral beams with preferential electron heating as expected for ITER. Confinement scaling studies indicate a strong ?? dependence, with a current dependence that is weaker than that observed at higher aspect ratio. Dimensionless scaling experiments indicate a strong increase of confinement with decreasing collisionality and a weak degradation with beta. The increase of confinement with ?? is due to reduced transport in the electron channel, while the improvement with plasma current is due to reduced transport in the ion channel related to the decrease in the neoclassical transport level. Improved electron confinement has been observed in plasmas with strong reversed magnetic shear, showing the existence of an electron internal transport barrier (eITB). The development of the eITB may be associated with a reduction in the growth of microtearing modes in the plasma core. Perturbative studies show that while L-mode plasmas with reversed magnetic shear and an eITB exhibit slow changes of L?e across the profile after the pellet injection, H-mode plasmas with a monotonic q-profile and no eITB show no change in this parameter after pellet injection, indicating the existence of a critical gradient that may be related to the q-profile. Both linear and non-linear simulations indicate the potential importance of ETG modes at the lowest ??. Localized measurements of high-? fluctuations exhibit a sharp decrease in signal amplitude levels across the L-H transition, associated with a decrease in both ion and electron transport, and a decrease in calculated linear microinstability growth rates across a wide ?-range, from the ITG/TEM regime up to the ETG regime.
National Spherical Torus Experiment (NSTX) | U.S. DOE Office of Science
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Physics Design of the National High-power Advanced Torus Experiment
Menard, J E; Fu, G -Y; Gorelenkov, N; Kaye, S M; Kramer, G; Maingi, R; Neumeyer, C L; Sabbagh, S A; Soukhanovskii, V A
2007-07-18T23:59:59.000Z
Moving beyond ITER toward a demonstration power reactor (Demo) will require the integration of stable high fusion gain in steady-state, advanced methods for dissipating very high divertor heat-fluxes, and adherence to strict limits on in-vessel tritium retention. While ITER will clearly address the issue of high fusion gain, and new and planned long-pulse experiments (EAST, JT60-SA, KSTAR, SST-1) will collectively address stable steady-state highperformance operation, none of these devices will adequately address the integrated heat-flux, tritium retention, and plasma performance requirements needed for extrapolation to Demo. Expressing power exhaust requirements in terms of Pheat/R, future ARIES reactors are projected to operate with 60-200MW/m, a Component Test Facility (CTF) or Fusion Development Facility (FDF) for nuclear component testing (NCT) with 40-50MW/m, and ITER 20-25MW/m. However, new and planned long-pulse experiments are currently projected to operate at values of Pheat/R no more than 16MW/m. Furthermore, none of the existing or planned experiments are capable of operating with very high temperature first-wall (Twall = 600-1000C) which may be critical for understanding and ultimately minimizing tritium retention with a reactor-relevant metallic first-wall. The considerable gap between present and near-term experiments and the performance needed for NCT and Demo motivates the development of the concept for a new experiment — the National High-power advanced-Torus eXperiment (NHTX) — whose mission is to study the integration of a fusion-relevant plasma-material interface with stable steady-state high-performance plasma operation.
Princeton Plasma Physics Laboratory
-wall interactions. Recently, there is growing use of lithium coatings, in particular, to control edge recyclingContinuous Improvement of H-Mode Discharge Performance with Progressively Increasing Lithium September 2011) Lithium wall coatings have been shown to reduce recycling, improve energy confinement
None
2013-08-27T23:59:59.000Z
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.
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)
2012-06-15T23:59:59.000Z
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.
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.
1999-11-14T23:59:59.000Z
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.
2009-10-21T23:59:59.000Z
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.
Princeton Plasma Physics Laboratory
a pulsed power load that would limit the lifetime of plasma-facing components (PFCs) unless the energyEdge-Localized-Mode Suppression through Density-Profile Modification with Lithium-Wall Coatings to low-n peeling or ballooning modes, while broader pressure profiles stabilized the post-Li discharges
The Columbia Non-neutral Torus
Thomas Sunn Pedersen
2009-09-23T23:59:59.000Z
Final report for the Columbia Non-neutral Torus. This details the results from the design, construction and initial operation of the Columbia Non-neutral Torus.
The Condensate from Torus Knots
A. Gorsky; A. Milekhin; N. Sopenko
2015-06-22T23:59:59.000Z
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.
Reactor assessments of advanced bumpy torus configurations
Uckan, N.A.; Owen, L.W.; Spong, D.A.; Miller, R.L.; Ard, W.B.; Pipkins, J.F.; Schmitt, R.J.
1983-01-01T23:59:59.000Z
Recently, several configurational approaches and concept improvement schemes were introduced for enhancing the performance of the basic ELMO Bumpy Torus (EBT) concept and for improving its reactor potential. These configurations include planar racetrack and square geometries, Andreoletti coil systems, and bumpy torus-stellarator hybrids (which include twisted racetrack and helical axis stellarator-snakey torus). Preliminary evaluations of reactor implications of each of these configurations have been carried out based on magnetics (vacuum) calculations, transport and scaling relationships, and stability properties. Results indicate favorable reactor projections with a significant reduction in reactor physical size as compared to conventional EBT reactor designs carried out in the past.
Methanol in the L1551 Circumbinary Torus
Glenn J. White; C. W. M. Fridlund; P. Bergman; A. Beardsmore; Rene Liseau; R. R. Phillips
2006-09-25T23:59:59.000Z
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.
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
Initial Data for General Relativity Containing a Marginally Outer Trapped Torus
Sascha Husa
1996-06-15T23:59:59.000Z
Asymptotically flat, time-symmetric, axially symmetric and conformally flat initial data for vacuum general relativity are studied numerically on $R^3$ with the interior of a standard torus cut out. By the choice of boundary condition the torus is marginally outer trapped, and thus a surface of minimal area. Apart from pure scaling the standard tori are parameterized by a radius $a\\in [0,1]$, where $a=0$ corresponds to the limit where the boundary torus degenerates to a circle and $a=1$ to a torus that touches the axis of symmetry. Noting that these tori are the orbits of a $U(1)\\times U(1)$ conformal isometry allows for a simple scheme to solve the constraint, involving numerical solution of only ordinary differential equations.The tori are unstable minimal surfaces (i.e. only saddle points of the area functional) and thus can not be apparent horizons, but are always surrounded by an apparent horizon of spherical topology, which is analyzed in the context of the hoop conjecture and isoperimetric inequality for black holes.
Major Milestone: PPPL completes first quadrant of the heart of the National
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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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn12electron 9November 6,Bradbury ScienceSpherical Torus
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
2007-04-25T23:59:59.000Z
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
2008-03-28T23:59:59.000Z
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
2006-11-21T23:59:59.000Z
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.
FY 2006 Miniature Spherical Retroreflectors Final Report
Anheier, Norman C.; Bernacki, Bruce E.; Krishnaswami, Kannan
2006-12-28T23:59:59.000Z
Research done by the Infrared Photonics team at Pacific Northwest National Laboratory (PNNL) is focused on developing miniature spherical retroreflectors using the unique optical and material properties of chalcogenide glass to reduce both performance limiting spherical aberrations. The optimized optical performance will provide efficient signal retroreflection that enables a broad range of remote detection scenarios for mid-wave infrared (MWIR) and long-wave infrared (LWIR) sensing applications. Miniature spherical retroreflectors can be developed to aid in the detection of signatures of nuclear proliferation or other chemical vapor or radiation signatures. Miniature spherical retroreflectors are not only well suited to traditional LIDAR methods for chemical plume detection and identification, but could enable remote detection of difficult semi-volatile chemical materials or low level radiation sources.
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)
2007-12-25T23:59:59.000Z
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.
A Novel Demountable TF Joint Design for Low Aspect Ratio Spherical Torus Tokamaks
Robert D. Woolley
2009-06-11T23:59:59.000Z
A novel shaped design for the radial conductors and demountable electrical joints connecting inner and outer legs of copper TF system conductors in low aspect ratio tokamaks is described and analysis results are presented. Specially shaped designs can optimize profiles of electrical current density, magnetic force, heating, and mechanical stress.
A Novel Demountable TF Joint Design for Low Aspect Ratio Spherical Torus Tokamaks
R.D. Woolley
2009-05-29T23:59:59.000Z
A novel shaped design for the radial conductors and demountable electrical joints connecting inner and outer legs of copper TF system conductors in low aspect ratio tokamaks is described and analysis results are presented. Specially shaped designs can optimize profiles of electrical current density, magnetic force, heating, and mechanical stress.
Effects of Large Area Liquid Lithium Limiters on Spherical Torus Plasmas
R. Kaita; R. Majeski; M. Boaz; P. Efthimion; G. Gettelfinger; T. Gray; D. Hoffman; S. Jardin; H. Kugel; P. Marfuta; T. Munsat; C. Neumeyer; S. Raftopoulos; V. Soukhanovskii; J. Spaleta; G. Taylor; J. Timberlake; R. Woolley; L. Zakharov; M. Finkenthal; D. Stutman; L. Delgado-Aparicio; R.P. Seraydarian; G. Antar; R. Doerner; S. Luckhardt; M. Baldwin; R.W. Conn; R. Maingi; M. Menon; R. Causey; D. Buchenauer; M. Ulrickson; B. Jones; D. Rodgers
2004-06-07T23:59:59.000Z
Use of a large-area liquid lithium surface as a first wall has significantly improved the plasma performance in the Current Drive Experiment-Upgrade (CDX-U) at the Princeton Plasma Physics Laboratory. Previous CDX-U experiments with a partially-covered toroidal lithium limiter tray have shown a decrease in impurities and the recycling of hydrogenic species. Improvements in loading techniques have permitted nearly full coverage of the tray surface with liquid lithium. Under these conditions, there was a large drop in the loop voltage needed to sustain the plasma current. The data are consistent with simulations that indicate more stable plasmas having broader current profiles, higher temperatures, and lowered impurities with liquid lithium walls. As further evidence for reduced recycling with a liquid lithium limiter, the gas puffing had to be increased by up to a factor of eight for the same plasma density achieved with an empty toroidal tray limiter.
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
2010-05-19T23:59:59.000Z
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.
Torus CLAS12-Superconducting Magnet Quench Analysis
Kashikhin, V S; Elouadhiri, L; Ghoshal, P K; Kashy, D; Makarov, A; Pastor, O; Quettier, L; Velev, G; Wiseman, M
2014-06-01T23:59:59.000Z
The JLAB Torus magnet system consists of six superconducting trapezoidal racetrack-type coils assembled in a toroidal configuration. These coils are wound with SSC-36 Nb-Ti superconductor and have the peak magnetic field of 3.6 T. The first coil manufacturing based on the JLAB design began at FNAL. The large magnet system dimensions (8 m diameter and 14 MJ of stored energy) dictate the need for quench protection. Each coil is placed in an aluminum case mounted inside a cryostat and cooled by 4.6 K supercritical helium gas flowing through a copper tube attached to the coil ID. The large coil dimensions and small cryostat thickness drove the design to challenging technical solutions, suggesting that Lorentz forces due to transport currents and eddy currents during quench and various failure scenarios are analyzed. The paper covers the magnet system quench analysis using the OPERA3d Quench code.
Persistent Density Perturbations at Rational q Surfaces Following Pellet Injection in the Joint European Torus
From Use Cases of the Joint European Torus towards Integrated Commissioning Requirements of the ITER Tokamak
Zero point energy on extra dimensions: Noncommutative torus
Fabi, S.; Harms, B.; Karatheodoris, G. [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, Alabama 35487-0324 (United States)
2007-09-15T23:59:59.000Z
In this paper we calculate the zero point energy density experienced by observers on M{sup 4} due to a massless scalar field defined throughout M{sup 4}xT{sub F}{sup 2}, where T{sub F}{sup 2} are fuzzy extra dimensions. Using the Green's function approach we calculate the energy density for the commutative torus and the fuzzy torus. We also calculate the energy density for the fuzzy torus using the Hamiltonian approach. Agreement is shown between the Green's function and Hamiltonian approaches.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Michael, J. Robert; Volkov, Anatoliy
2015-01-23T23:59:59.000Z
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; Paturlemore »& 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.« less
Fermions in spherical field theory
Dean Lee
1999-01-07T23:59:59.000Z
We derive the spherical field formalism for fermions. We find that the spherical field method is free from certain difficulties which complicate lattice calculations, such as fermion doubling, missing axial anomalies, and computational problems regarding internal fermion loops.
SPHERICALLY-ACTUATED PLATFORM MANIPULATOR
Williams II, Robert L.
1 SPHERICALLY-ACTUATED PLATFORM MANIPULATOR Robert L. Williams II Dana B. Poling Ohio University://www.ent.ohiou.edu/~bobw #12;2 SPHERICALLY-ACTUATED PLATFORM MANIPULATOR Robert L. Williams II and Dana B. Poling Ohio University Athens, OH 45701 KEYWORDS: Spherical Actuation, Platform Manipulator, Parallel Robot ABSTRACT
Efficient Subtorus Processor Allocation in a Multi-Dimensional Torus
Weizhen Mao; Jie Chen; William Watson
2005-11-30T23:59:59.000Z
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.
Hollow spherical shell manufacture
O'Holleran, Thomas P. (Belleville, MI)
1991-01-01T23:59:59.000Z
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.
Hollow spherical shell manufacture
O'Holleran, T.P.
1991-11-26T23:59:59.000Z
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.
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)
2009-08-31T23:59:59.000Z
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)
Admissibility condition and nontrivial indices on a noncommutative torus
Nagao, Keiichi [Theoretical Physics Laboratory, College of Education, Ibaraki University, Mito 310-8512 (Japan)
2006-03-15T23:59:59.000Z
We study the index of the Ginsparg-Wilson Dirac operator on a noncommutative torus numerically. To do this, we first formulate an admissibility condition which suppresses the fluctuation of gauge fields. Assuming this condition, we generate gauge configurations randomly, and find various configurations with nontrivial indices. We show one example of configurations with index 1 explicitly. This result provides the first evidence that nontrivial indices can be naturally defined on the noncommutative torus by utilizing the Ginsparg-Wilson relation and the admissibility condition.
Introduction to spherical field theory
Dean Lee
1998-11-12T23:59:59.000Z
Spherical field theory is a new non-perturbative method for studying quantum field theories. It uses the spherical partial wave expansion to reduce a general d-dimensional Euclidean field theory into a set of coupled one-dimensional systems. The coupled one-dimensional systems are then converted to partial differential equations and solved numerically. We demonstrate the methods of spherical field theory by analyzing Euclidean phi^4 theory in two dimensions.
Nonlinear spherical Alfven waves
Ulf Torkelsson; G. Christopher Boynton
1997-09-23T23:59:59.000Z
We present an one-dimensional numerical study of Alfven waves propagating along a radial magnetic field. Neglecting losses, any spherical Alfven wave, no matter how small its initial amplitude is, becomes nonlinear at sufficiently large radii. From previous simulations of Alfven waves in plane parallel atmospheres we did expect the waves to steepen and produce current sheets in the nonlinear regime, which was confirmed by our new calculations. On the other hand we did find that even the least nonlinear waves were damped out almost completely before 10 solar radii. A damping of that kind is required by models of Alfven wave-driven winds from old low-mass stars as these winds are mainly accelerated within a few stellar radii.
UCID-20974 Spherical Explosions
Office of Scientific and Technical Information (OSTI)
be those of the Laboratory. Work prrformed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under Contract W-7405-Eng-48. 7 ' ....
The Gauss-Bonnet Theorem for the noncommutative two torus
Connes, Alain
2009-01-01T23:59:59.000Z
In this paper we show that the value at zero of the zeta function of the Laplacian on the non-commutative two torus, endowed with its canonical conformal structure, is independent of the choice of the volume element (Weyl factor) given by a (non-unimodular) state. We had obtained, in the late eighties, in an unpublished computation, a general formula for this value at zero involving modified logarithms of the modular operator of the state. We give here the detailed computation and prove that the result is independent of the Weyl factor as in the classical case, thus proving the analogue of the Gauss-Bonnet theorem for the noncommutative two torus.
Spherically symmetric cosmology: resource paper
A. A. Coley; W. C. Lim; G. Leon
2008-03-06T23:59:59.000Z
We use the 1+3 frame formalism to write down the evolution equations for spherically symmetric models as a well-posed system of first order PDEs in two variables, suitable for numerical and qualitative analysis.
UCID-20974 Spherical Explosions
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem Not FoundInformation DOEInformation Summary Big*The LA:UR-EnergyUCID-20974
facility, the National Spherical Torus Experiment, came into operation in 1999, ahead of schedule reaction possible. · Materials and by-products unsuitable for weapons production. · Radiological hazards
Major Milestone: PPPL completes first quadrant of the heart of...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
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...
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
Egedal, Jan
Calibration of the Joint European Torus energetic ion and alpha particle collective Thomson is calibrated assuming blackbody emission from the torus vacuum vessel ~VV! and using electron cyclotron emission ~ECE!. The 32 receiver channels are absolutely calibrated with a mechanical chopper
Egedal, Jan
Calibration of the Joint European Torus energetic ion and alpha particle collective Thomson Torus JET energetic ion and alpha particle collective Thomson scattering diagnostic is calibrated . The 32 receiver channels are absolutely calibrated with a mechanical chopper in the quasioptical arm
Fast waves and electron current drive in the Irvine Torus
Platt, R.C.
1987-01-01T23:59:59.000Z
This work reports the results of experimental studies of the fast wave with frequencies near the mean gyro-frequency in magnetized, toroidal plasmas with comparison to theory. Experiment investigating fast-wave dispersion and damping, and the use of unidirectional fast waves to drive steady-state electron currents were performed on the Irvine Torus. The wave was excited in the plasmas by a phased array antenna which allowed launching of uni- or bi-directional fast waves around the torus. Probe measurements of the angle of propagation of wave energy, radial wavelengths, and the direction and magnitude of radial wave phase velocities were found to be in good agreement with predictions from cold plasma theory. Measurements of fast-wave damping showed the observed damping lengths to be anomalously short when compared to predictions for electron Landau damping, transit-time magnetic pumping, and collisional damping, but may be explained by effects due to fast-wave scattering from drift-wave density fluctuations. Steady-state electron currents were driven by unidirectional fast waves. Up to 14% of the wave energy was converted to poloidal magnetic field energy. The maximum current observed was found to be in rough agreement with a prediction from quasi-linear theory.
Low-Recycling Conditions and Improved Core Confinement in Steady-State Operation Scenarios in JET (Joint European Torus)
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
2015-01-23T23:59:59.000Z
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.
Exponential Time Decay Estimates for the Landau Equation on Torus
Kung-Chien Wu
2013-01-04T23:59:59.000Z
We study the time decay estimates for the linearized Landau equation on torus when the initial perturbation is not necessarily smooth. Our result reveals the kinetic and fluid aspects of the equation. We design a Picard-type iteration and Mixture lemma for constructing the increasingly regular kinetic like waves, they are carried by transport equations and have exponential time decay rate. The fluid like waves are constructed as part of the long-wave expansion in the spectrum of the Fourier mode for the space variable and the time decay rate depends on the size of the domain. The Mixture lemma plays an important role in this paper, this lemma is parallel to Boltzmann equation but the proof is more challenge.
Pointwise Behavior of the Linearized Boltzmann Equation on Torus
Kung-Chien Wu
2013-01-04T23:59:59.000Z
We study the pointwise behavior of the linearized Boltzmann equation on torus for non-smooth initial perturbation. The result reveals both the fluid and kinetic aspects of this model. The fluid-like waves are constructed as part of the long-wave expansion in the spectrum of the Fourier mode for the space variable, the time decay rate of the fluid-like waves depends on the size of the domain. We design a Picard-type iteration for constructing the increasingly regular kinetic-like waves, which are carried by the transport equations and have exponential time decay rate. Moreover, the mixture lemma plays an important role in constructing the kinetic-like waves, we supply a new proof of this lemma to avoid constructing explicit solution of the damped transport equations
Charged particle driver for ICF using an accelerated, focused compact torus
Meeker, D.J.; Hammer, J.H.; Hartman, C.W.
1986-06-01T23:59:59.000Z
We report the status of evaluating an accelerated and focused compact torus as a driver for ICF. We are studying the acceleration and focusing aspects experimentally in the RACE facility, a recently completed ring generator coupled to a 260 kJ acceleration bank. Compact torus and ICF target interaction is being investigated with PIC codes and LASNEX, a 2D magneto-hydrodynamics code. Final conditions required of the CT are discussed as well as coupling issues such as superthermal electron production. We conclude with an economic evaluation of a few 100 MW reactor driven by a compact torus. 9 refs., 5 figs., 1 tab.
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)
2013-08-15T23:59:59.000Z
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.
MODELING RESULTS FROM CESIUM ION EXCHANGE PROCESSING WITH SPHERICAL RESINS
Nash, C.; Hang, T.; Aleman, S.
2011-01-03T23:59:59.000Z
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.
Spherically symmetric scalar field collapse
Koyel Ganguly; Narayan Banerjee
2012-10-03T23:59:59.000Z
It is shown that a scalar field, minimally coupled to gravity may have collapsing modes even when the energy condition is violated, that is, for $(\\rho+3p)<0$. This result may be useful in the investigation of the possible clustering of dark energy. All the examples dealt with have apparent horizons which form before the formation of the singularity. The singularities formed are shell focusing in nature. The density of the scalar field distribution is seen to diverge at singularity. The Ricci scalar also diverges at the singularity. The interior spherically symmetric metric is matched with exterior Vaidya metric at the hypersurface and the appropriate junction conditions are obtained.
Nonlinear coupling of tearing fluctuations in the Madison Symmetric Torus
Sarff, J.S.; Almagri, A.F.; Cekic, M.; Den Hartog, D.J.; Fiksel, G.; Hokin, S.A.; Ji, H.; Prager, S.C.; Shen, W.; Stoneking, M.R. (Wisconsin Univ., Madison, WI (United States)); Assadi, S. (Fermi National Accelerator Lab., Batavia, IL (United States)); Sidikman, K.L. (Oak Ridge National Lab., TN (United States))
1992-11-01T23:59:59.000Z
Three-wave, nonlinear, tearing mode coupling has been measured in the Madison Symmetric Torus (MST) reversed-field pinch (RFP) [Fusion Technol. 19, 131 (1991)] using bispectral analysis of edge magnetic fluctuations resolved in k-space. The strength of nonlinear three-wave interactions satisfying the sum rules m[sub 1] + m[sub 2] = m[sub 3] and n[sub 1] + n[sub 2] = n[sub 3] is measured by the bicoherency. In the RFP, m=l, n[approximately]2R/a (6 for MST) internally resonant modes are linearly unstable and grow to large amplitude. Large values of bicoherency occur for two m=l modes coupled to an m=2 mode and the coupling of intermediate toroidal modes, e.g., n=6 and 7 coupled to n=13. These experimental bispectral features agree with predicted bispectral features derived from MHD computation. However, in the experiment, enhanced coupling occurs in the crash'' phase of a sawtooth oscillation concomitant with a broadened mode spectrum suggesting the onset of a nonlinear cascade.
Reversed-field pinch studies in the Madison Symmetric Torus
Hokin, S.; Almagri, A.; Cekic, M.; Chapman, B.; Crocker, N.; Den Hartog, D.J.; Fiksel, G.; Henry, J.; Ji, H.; Prager, S.; Sarff, J.; Scime, E.; Shen, W.; Stoneking, M.; Watts, C.
1993-04-03T23:59:59.000Z
Studies of large-size (R = 1.5 m, a = 0.5 m), moderate current (I < 750 kA) reversed-field pinch (RFP) plasmas are carried out in the Madison Symmetric Torus in order to evaluate and improve RFP confinement, study general toroidal plasma MHD issues, determine the mechanism of the RFP dynamo, and measure fluctuation-induced transport and anomalous ion heating. MST confinement has been improved by reduction of magnetic field errors with correction coils in the primary circuit and reduction of impurities using boronization; high densities have been achieved with hydrogen pellet injection. MHD tearing modes with poloidal mode number m = 1 and toroidal mode numbers n = 5--7 are prevalent and nonlinearly couple to produce sudden relaxations akin to tokamak sawteeth. Edge fluctuation-induced transport has been measured with a variety of insertable probes. Ions exhibit anomalous heating, with increases of ion temperature occuring during strong MHD relaxation. The RFP dynamo has been studied with attention to various possible mechanisms, including motion-EMF drive, the Hall effect, and superthermal electrons. Initial profile control experiments have begun using insertable biased probes and plasma guns. The toroidal field capacity of MST will be upgraded during Summer, 1993 to allow low-current tokamak operation as well as improved RFP operation.
Nonlinear coupling of tearing fluctuations in the Madison Symmetric Torus
Sarff, J.S.; Almagri, A.F.; Cekic, M.; Den Hartog, D.J.; Fiksel, G.; Hokin, S.A.; Ji, H.; Prager, S.C.; Shen, W.; Stoneking, M.R. [Wisconsin Univ., Madison, WI (United States); Assadi, S. [Fermi National Accelerator Lab., Batavia, IL (United States); Sidikman, K.L. [Oak Ridge National Lab., TN (United States)
1992-11-01T23:59:59.000Z
Three-wave, nonlinear, tearing mode coupling has been measured in the Madison Symmetric Torus (MST) reversed-field pinch (RFP) [Fusion Technol. 19, 131 (1991)] using bispectral analysis of edge magnetic fluctuations resolved in ``k-space. The strength of nonlinear three-wave interactions satisfying the sum rules m{sub 1} + m{sub 2} = m{sub 3} and n{sub 1} + n{sub 2} = n{sub 3} is measured by the bicoherency. In the RFP, m=l, n{approximately}2R/a (6 for MST) internally resonant modes are linearly unstable and grow to large amplitude. Large values of bicoherency occur for two m=l modes coupled to an m=2 mode and the coupling of intermediate toroidal modes, e.g., n=6 and 7 coupled to n=13. These experimental bispectral features agree with predicted bispectral features derived from MHD computation. However, in the experiment, enhanced coupling occurs in the ``crash`` phase of a sawtooth oscillation concomitant with a broadened mode spectrum suggesting the onset of a nonlinear cascade.
Ideal magnetohydrodynamic equilibrium in a non-symmetric topological torus
Weitzner, Harold [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States)] [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States)
2014-02-15T23:59:59.000Z
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.
Electron Bernstein Wave Experiment on the Madison Symmetric Torus
Anderson, J. K.; Burke, D. R.; Forest, C. B.; Goetz, J. A.; Kaufman, M. C.; Seltzman, A. H. [Department of Physics, University of Wisconsin, Madison WI 53706 (United States)
2009-11-26T23:59:59.000Z
A system to heat electrons and possibly drive off-axis field-aligned current is under development on the Madison Symmetric Torus RFP. Staged experiments have reached an input power of 150 kW at 3.6G Hz and have produced a localized increase in SXR emission during rf injection. This measured emission is consistent with modeling in its location, energy spectrum and dependence on radial diffusion within the plasma. The emission is strongest in the region where ray tracing predicts deposition of the injected power. The multi-chord SXR camera used is sensitive to 4-7 keV photons. Enhanced emission in this energy range is consistent with Fokker-Plank modeling of EBW injection. The enhanced SXR emission vanishes quickly when radial diffusion in the plasma is high (as indicated by m = 0 magnetic activity); this is also consistent with Fokker-Plank modeling. An increase of boron emission (and presumably boron within the plasma) is also observed during EBW injection. This presents an alternative explanation to the enhanced SXR emission. Subsequent experiments with a different antenna at 100 kW input showed a small increase in SXR emission near 3 keV. A higher frequency experiment (5.5 GHz) with more input power available is currently under construction. Initial tests are centered on a circular waveguide launcher which requires only a 5 cm circular port in the vacuum vessel and has a target launch power of 400 kW.
A component test facility based on the spherical tokamak
Peng, Yueng Kay Martin [ORNL; Fogarty, P. J. [Oak Ridge National Laboratory (ORNL); Burgess, Thomas W [ORNL; Strickler, Dennis J [ORNL; Nelson, Brad E [ORNL; Tsai, C. C. [Oak Ridge National Laboratory (ORNL)
2005-01-01T23:59:59.000Z
Recent experiments (Synakowski et al 2004 Nucl. Fusion 43 1648, Lloyd et al 2004 Plasma Phys. Control. Fusion 46 13477) on the Spherical Tokamak (or Spherical Torus, ST) (Peng 2000 Phys. Plasmas 7 1681) have discovered robust plasma conditions, easing shaping, stability limits, energy confinement, self-driven current and sustainment. This progress has encouraged an update of the plasma conditions and engineering of a Component Test Facility (CTF), (Cheng 1998 Fusion Eng. Des. 38 219) which is a very valuable step in the development of practical fusion energy. The testing conditions in a CTF are characterized by high fusion neutron fluxes Gamma(n) approximate to 8.8 x 10(13) n s(-1) cm(-2) ('wall loading' W-L approximate to 2 MW m(-2)), over size-scale > 10(5) cm(2) and depth-scale > 50 cm, delivering > 3 accumulated displacement per atom per year ('neutron fluence' > 0.3 MW yr(-1) m(-2)) (Abdou et al 1999 Fusion Technol. 29 1). Such conditions are estimated to be achievable in a CTF with R-0 = 1.2 m, A = 1.5, elongation similar to 3, I-p similar to 12 MA, B-T similar to 2.5 T, producing a driven fusion burn using 47 MW of combined neutral beam and RF heating power. A design concept that allows straight-line access via remote handling to all activated fusion core components is developed and presented. The ST CTF will test the lifetime of single-turn, copper alloy centre leg for the toroidal field coil without an induction solenoid and neutron shielding and require physics data on solenoid-free plasma current initiation, ramp-up to and sustainment at multiple megaampere level. A systems code that combines the key required plasma and engineering science conditions of CTF has been prepared and utilized as part of this study. The results show high potential for a family of relatively low cost CTF devices to suit a range of fusion engineering and technology test missions.
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
2008-05-27T23:59:59.000Z
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.
Three-point spherical mirror mount
Cutburth, R.W.
1984-01-23T23:59:59.000Z
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.
DOEIEA-1108 ENVIRONMENTAL ASSESSMENT THE NATIONAL SPHERICAL TOKAMAK...
Broader source: Energy.gov (indexed) [DOE]
"no action" alternative, Le., not dismantling PLT and not constructing NSTX for plasma research. This alternative would preclude efforts to investigate a promising alternative...
Preliminary Physics Motivation and Engineering Design Assessment of the National High Power Torus
Robert D. Woolley
2009-06-11T23:59:59.000Z
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.
Gravitational Energy in Spherical Symmetry
Sean A. Hayward
2002-02-17T23:59:59.000Z
Various properties of the Misner-Sharp spherically symmetric gravitational energy E are established or reviewed. In the Newtonian limit of a perfect fluid, E yields the Newtonian mass to leading order and the Newtonian kinetic and potential energy to the next order. For test particles, the corresponding Hajicek energy is conserved and has the behaviour appropriate to energy in the Newtonian and special-relativistic limits. In the small-sphere limit, the leading term in E is the product of volume and the energy density of the matter. In vacuo, E reduces to the Schwarzschild energy. At null and spatial infinity, E reduces to the Bondi-Sachs and Arnowitt-Deser-Misner energies respectively. The conserved Kodama current has charge E. A sphere is trapped if E>r/2, marginal if E=r/2 and untrapped if E0, and temporal and untrapped if Eenergy condition. It follows that E>=0 on an untrapped spatial hypersurface with regular centre, and E>=r_0/2 on an untrapped spatial hypersurface bounded at the inward end by a marginal sphere of radius r_0. All these inequalities extend to the asymptotic energies, recovering the Bondi-Sachs energy loss and the positivity of the asymptotic energies, as well as proving the conjectured Penrose inequality for black or white holes. Implications for the cosmic censorship hypothesis and for general definitions of gravitational energy are discussed.
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
2015-06-01T23:59:59.000Z
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
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)
2011-12-15T23:59:59.000Z
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.
FY 2008 Miniature Spherical Retroreflectors – Final Report
Anheier, Norman C.; Bernacki, Bruce E.; Klymyshyn, Nicholas A.; Krishnaswami, Kannan; Rodriguez, Carmen P.
2009-02-01T23:59:59.000Z
Through the duration of the NNSA Office of Nuclear Nonproliferation Research and Development (NA-22) Miniature Spherical Retroreflectors lifecycle project, our research team focused on developing solutions to the fabrication bottleneck that has inhibited development and deployment of wide-angle optically interrogated chemical and radiological remote sensing technology. Our team advanced the concept of step-index clad retroreflectors to approximate an optimized, but yet unrealized spherical gradient index design. An intensive numerical simulation effort was undertaken that resulted in optimized step-index optical designs for mid-infrared applications. Geometric optics ray trace modeling was performed to better understand the geometrical dependencies of the miniature spherical retroreflector application. We adopted and advanced the concept of optical cross section, a metric that provides relative performance comparisons between different retroreflector designs and our cross-section analysis demonstrated that our step-index design provided 90% of the range capacity of the ideal spherical index design.
Method for making spherical binderless pellets
Grubbs, Donald K. (Rector, PA); Kochanowski, Andrew T. (Spring Church, PA)
1983-01-01T23:59:59.000Z
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.
Localized waves with spherical harmonic symmetries
Mills, M. S.
We introduce a class of propagation invariant spatiotemporal optical wave packets with spherical harmonic symmetries in their field configurations. The evolution of these light orbitals is considered theoretically in ...
DEPLETED MAGNETIC FLUX TUBES AS PROBES OF THE IO TORUS PLASMA
Russell, Christopher T.
and Astronomy, University of Iowa, Iowa City, IA 52242, USA ABSTRACT On the initial pass by Io the Galileo that they were depleted in their energy content. These tubes have not been seen on every return to the Io torus balance with neighboring flux tubes in steady state. Figure 1 shows such pressure balance. The magnitude
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
Local well-posedness for the Zakharov system on multidimensional torus
Kishimoto, Nobu
2011-01-01T23:59:59.000Z
The initial value problem of the Zakharov system on two dimensional torus with general period is shown to be locally well-posed in the Sobolev spaces of optimal regularity, including the energy space. Proof relies on a standard iteration argument using the Bourgain norms. The same strategy is also applicable to three and higher dimensional cases.
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
Direct-illumination spherical-target experiments
Johnson, R.R.
1982-01-01T23:59:59.000Z
A set of spherical target experiments was designed to evaluate the effectiveness of three techniques for achieving higher convergence implosions. They are (1) cryogenically frozen fuel layers, (2) submicron wavelength laser light, and (3) temporally tailored pulse shapes. A second set of experiments provides information about energy transport by thermal and suprathermal electrons and uses multilayered targets as an integral component of the diagnostics. These results, in conjunction with existing laser-target coupling data, provide a more comprehensive test of our understanding of laser plasma interaction, energy transport, and hydrodynamic response of small scale spherical laser fusion experiments.
Spherical Harmonic Decomposition on a Cubic Grid
Charles W. Misner
1999-10-12T23:59:59.000Z
A method is described by which a function defined on a cubic grid (as from a finite difference solution of a partial differential equation) can be resolved into spherical harmonic components at some fixed radius. This has applications to the treatment of boundary conditions imposed at radii larger than the size of the grid, following Abrahams, Rezzola, Rupright et al.(gr-qc/9709082}. In the method described here, the interpolation of the grid data to the integration 2-sphere is combined in the same step as the integrations to extract the spherical harmonic amplitudes, which become sums over grid points. Coordinates adapted to the integration sphere are not needed.
Simple flexible polymers in a spherical cage
M. Marenz; J. Zierenberg; H. Arkin; W. Janke
2012-12-26T23:59:59.000Z
We report the results of Monte Carlo simulations investigating the effect of a spherical confinement within a simple model for a flexible homopolymer. We use the parallel tempering method combined with multi-histogram reweighting analysis and multicanonical simulations to investigate thermodynamical observables over a broad range of temperatures, which enables us to describe the behavior of the polymer and to locate the freezing and collapse transitions. We find a strong effect of the spherical confinement on the location of the collapse transition, whereas the freezing transition is hardly effected.
ELECTRON THERMAL TRANSPORT IN THE MADISON SYMMETRIC TORUS
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power AdministrationField Campaign:INEA :Work withJerseyMarketsWhy Report419: RecordlELECTRON
Filamentary current structures in the Madison Symmetric Torus
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power AdministrationField8,Dist.New Mexico Feb.Information 9 Default Caption and Credits8
Line-tension effects on heterogeneous nucleation on a spherical substrate and in a spherical cavity
Masao Iwamatsu
2015-03-17T23:59:59.000Z
The line-tension effects on heterogeneous nucleation are considered when a spherical lens-shaped nucleus is nucleated on top of a spherical substrate and on the bottom of the wall of a spherical cavity. The effect of line tension on the nucleation barrier can be separated from the usual volume term. As the radius of the substrate increases, the nucleation barrier decreases and approaches that of a flat substrate. However, as the radius of the cavity increases, the nucleation barrier increases and approaches that of a flat substrate. A small spherical substrate is a less active nucleation site than a flat substrate, and a small spherical cavity is a more active nucleation site than a flat substrate. In contrast, the line-tension effect on the nucleation barrier is maximum when the radii of the nucleus and the substrate or cavity become comparable. Therefore, by tuning the size of the spherical substrate or spherical cavity, the effect of the line tension can be optimized. These results will be useful in broad range of applications from material processing to understanding of global climate, where the heterogeneous nucleation plays a vital role.
Traces of holomorphic families of operators on the noncommutative torus and on Hilbert modules
Sara Azzali; Cyril Lévy; Carolina Neira Jiménez; Sylvie Paycha
2015-01-26T23:59:59.000Z
We revisit traces of holomorphic families of pseudodifferential operators on a closed manifold in view of geometric applications. We then transpose the corresponding analytic constructions to two different geometric frameworks; the noncommutative torus and Hilbert modules. These traces are meromorphic functions whose residues at the poles as well as the constant term of the Laurent expansion at zero (the latter when the family at zero is a differential operator) can be expressed in terms of Wodzicki residues and extended Wodzicki residues involving logarithmic operators. They are therefore local and contain geometric information. For holomorphic families leading to zeta regularised traces, they relate to the heat-kernel asymptotic coefficients via an inverse Mellin mapping theorem. We revisit Atiyah's L^2-index theorem by means of the (extended) Wodzicki residue and interpret the scalar curvature on the noncommutative two torus as an (extended) Wodzicki residue.
High-speed three-wave polarimeter-interferometer diagnostic for Madison symmetric torus
Deng, B. H.; Brower, D. L.; Ding, W. X.; Wyman, M. D.; Chapman, B. E.; Sarff, J. S. [Electrical Engineering Department, University of California, Los Angeles, California 90095 (United States); Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States)
2006-10-15T23:59:59.000Z
A high-speed three-wave polarimeter-interferometer diagnostic has been developed on the Madison symmetric torus reversed field pinch to provide simultaneous measurement of electron density and poloidal magnetic field profile evolution. With increased digitizer bandwidth, polarimetry noise due to aliasing and cross-talk is minimized, and time response improved. System performance is demonstrated by measurements of equilibrium profile evolution during fast events such as the sawtooth crash and pellet injection.
Brachistochrone of a Spherical Uniform Mass Distribution
David R. Mitchell
2008-08-23T23:59:59.000Z
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.
ATM SPHERIC SCIENCES THE DEPARTMENT OF
-time faculty and 143 undergraduates (Fall 2006), students in the Department of Atmospher- ic Sciences enjoyATM SPHERIC SCIENCES THE DEPARTMENT OF Department of Atmospheric Sciences Texas A&M University Atmospheric science, the study of the physics and chemistry of the atmosphere, includes meteorology
Spherically symmetric monopoles in noncommutative space
Moreno, E.F. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina) and Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315 (United States)
2005-08-15T23:59:59.000Z
We construct a spherically symmetric noncommutative space in three dimensions by foliating the space with concentric fuzzy spheres. We show how to construct a gauge theory in this space, and, in particular, we derive the noncommutative version of a Yang-Mills-Higgs theory. We find numerical monopole solutions of the equations of motion.
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
Multipole polarizability of a graded spherical particle
L. Dong; J. P. Huang; K. W. Yu; G. Q. Gu
2005-12-01T23:59:59.000Z
We have studied the multipole polarizability of a graded spherical particle in a nonuniform electric field, in which the conductivity can vary radially inside the particle. The main objective of this work is to access the effects of multipole interactions at small interparticle separations, which can be important in non-dilute suspensions of functionally graded materials. The nonuniform electric field arises either from that applied on the particle or from the local field of all other particles. We developed a differential effective multipole moment approximation (DEMMA) to compute the multipole moment of a graded spherical particle in a nonuniform external field. Moreover, we compare the DEMMA results with the exact results of the power-law graded profile and the agreement is excellent. The extension to anisotropic DEMMA will be studied in an Appendix.
Imaging with Spherically Bent Crystals or Reflectors
Bitter, M; Hill, K W; Scott, S; Ince-Cushman, A; Reinke, M; Podpaly, Y; Rice, J E; Beiersdorfer, P
2010-06-01T23:59:59.000Z
This paper consists of two parts: Part I describes the working principle of a recently developed x-ray imaging crystal spectrometer, where the astigmatism of spherically bent crystals is being used with advantage to record spatially resolved spectra of highly charged ions for Doppler measurements of the ion-temperature and toroidal plasmarotation- velocity profiles in tokamak plasmas. This type of spectrometer was thoroughly tested on NSTX and Alcator C-Mod, and its concept was recently adopted for the design of the ITER crystal spectrometers. Part II describes imaging schemes, where the astigmatism has been eliminated by the use of matched pairs of spherically bent crystals or reflectors. These imaging schemes are applicable over a wide range of the electromagnetic radiation, which includes microwaves, visible light, EUV radiation, and x-rays. Potential applications with EUV radiation and x-rays are the diagnosis of laserproduced plasmas, imaging of biological samples with synchrotron radiation, and lithography.
Generalized harmonic formulation in spherical symmetry
Evgeny Sorkin; Matthew W. Choptuik
2010-04-30T23:59:59.000Z
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.
Structure of the Spherical Black Hole Interior
A. Bonanno; S. Droz; W. Israel; S. M. Morsink
1994-11-18T23:59:59.000Z
The internal structure of a charged spherical black hole is still a topic of debate. In a nonrotating but aspherical gravitational collapse to form a spherical charged black hole, the backscattered gravitational wave tails enter the black hole and are blueshifted at the Cauchy horizon. This has a catastrophic effect if combined with an outflux crossing the Cauchy horizon: a singularity develops at the Cauchy horizon and the effective mass inflates. Recently a numerical study of a massless scalar field in the \\RN background suggested that a spacelike singularity may form before the Cauchy horizon forms. We will show that there exists an approximate analytic solution of the scalar field equations which allows the mass inflation singularity at the Cauchy horizon to exist. In particular, we see no evidence that the Cauchy horizon is preceded by a spacelike singularity.
Simulation of spherically expanding turbulent premixed flames
Ahmed, I.; Swaminathan, N.
2013-09-16T23:59:59.000Z
canonically im- portant configuration and its investigation is helpful to understand combustion in prac- tical devices such as the spark ignited internal combustion engine, modern stratified charge engines and accidental explosions of fuel vapour cloud... Simulation of spherically expanding turbulent premixed flames I. Ahmed, N. Swaminathan? Department of Engineering, Cambridge University, Cambridge, CB2 1PZ, UK. ?Corresponding author: Department of Engineering, Cambridge University, Trumpington...
Initial Results from the Lost Alpha Diagnostics on Joint European Torus
Darrow, Doug; Cecil, Ed; Ellis, Bob; Fullard, Keith; Hill, Ken; Horton, Alan; Kiptily, Vasily; Pedrick, Les; Reich, Matthias
2007-07-25T23:59:59.000Z
Two devices have been installed in the Joint European Torus (JET) vacuum vessel near the plasma boundary to investigate the loss of energetic ions and fusion products in general and alpha particles in particular during the upcoming JET experiments. These devices are (i) a set of multichannel thin foil Faraday collectors, and (ii) a well collimated scintillator which is optically connected to a charge-coupled device. Initial results, including the radial energy and poloidal dependence of lost ions from hydrogen and deuterium plasmas during the 2005–06 JET restart campaign, will be presented.
Topological Invariants and Ground-State Wave Functions of Topological Insulators on a Torus
Zhong Wang; Shou-Cheng Zhang
2014-01-25T23:59:59.000Z
We define topological invariants in terms of the ground states wave functions on a torus. This approach leads to precisely defined formulas for the Hall conductance in four dimensions and the topological magneto-electric $\\theta$ term in three dimensions, and their generalizations in higher dimensions. They are valid in the presence of arbitrary many-body interaction and disorder. These topological invariants systematically generalize the two-dimensional Niu-Thouless-Wu formula, and will be useful in numerical calculations of disordered topological insulators and strongly correlated topological insulators, especially fractional topological insulators.
Simulations of LH coupling in the Madison Symmetric Torus Reversed Field Pinch
Carlsson, J.; Smithe, D. [Tech-X Corporation, Boulder USA (United States); Cartert, M. [Oak Ridge National Laboratory, Oak Ridge (United States); Burke, D.; Kaufman, M.; Goetz, J. [University of Wisconsin, Madison (United States)
2007-09-28T23:59:59.000Z
Simulations using several codes are being performed in support of the LH experiment in the Madison Symmetric Torus (MST) Reversed Field Pinch (RFP). Due to the special requirements of the MST RFP configuration (tight-fitting conducting shell in which only minimal portholes can be tolerated), a novel interdigital line slow-wave launch structure is used, mounted below the mid plane on the inboard side. The unusual configuration made it necessary to modify the main RF coupling code, RANT3D/AORSA1D-H, which was primarily developed for tokamak simulations. Preliminary results will be presented.
Simulations of lower-hybrid coupling in the Madison Symmetric Torus
Carlsson, Johan; Smithe, David [Tech-X Corporation, Boulder, Colorado (United States); Carter, Mark [Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States); Kaufman, Mike [University of Wisconsin, Madison, Wisconsin (United States)
2009-11-26T23:59:59.000Z
Simulations of Lower Hybrid (LH) coupling in the Madison Symmetric Torus (MST) Reversed Field Pinch (RFP) will be presented. Due to the special requirements of the RFP configuration (tight-fitting conducting shell in which only minimal portholes are acceptable), an unusual interdigital line slow-wave antenna is used, mounted below the mid plane on the inboard side. A number of codes are used, including VORPAL, RANT3D/AORSA1D-H and MWS, each solving different equations and using different algorithms. Output from the different codes will be presented and compared to verify the simulation results.
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
Soret Motion of a Charged Spherical Colloid
Seyyed Nader Rasuli; Ramin Golestanian
2008-08-05T23:59:59.000Z
The thermophoretic motion of a charged spherical colloidal particle and its accompanying cloud of counterions and co-ions in a temperature gradient is studied theoretically. Using the Debye-Huckel approximation, the Soret drift velocity of a weakly charged colloid is calculated analytically. For highly charged colloids, the nonlinear system of electrokinetic equations is solved numerically, and the effects of high surface potential, dielectrophoresis, and convection are examined. Our results are in good agreement with some of the recent experiments on highly charged colloids without using adjustable parameters.
Casimir Energy of a Spherical Shell
M. E. Bowers; C. R. Hagen
1998-06-23T23:59:59.000Z
The Casimir energy for a conducting spherical shell of radius $a$ is computed using a direct mode summation approach. An essential ingredient is the implementation of a recently proposed method based on Cauchy's theorem for an evaluation of the eigenfrequencies of the system. It is shown, however, that this earlier calculation uses an improper set of modes to describe the waves exterior to the sphere. Upon making the necessary corrections and taking care to ensure that no mathematically ill-defined expressions occur, the technique is shown to leave numerical results unaltered while avoiding a longstanding criticism raised against earlier calculations of the Casimir energy.
Spherically Symmetric Gravitational Collapse of Perfect Fluids
P. D. Lasky; A. W. C. Lun
2006-10-31T23:59:59.000Z
Formulating a perfect fluid filled spherically symmetric metric utilizing the 3+1 formalism for general relativity, we show that the metric coefficients are completely determined by the mass-energy distribution, and its time rate of change on an initial spacelike hypersurface. Rather than specifying Schwarzschild coordinates for the exterior of the collapsing region, we let the interior dictate the form of the solution in the exterior, and thus both regions are found to be written in one coordinate patch. This not only alleviates the need for complicated matching schemes at the interface, but also finds a new coordinate system for the Schwarzschild spacetime expressed in generalized Painleve-Gullstrand coordinates.
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
2011-02-24T23:59:59.000Z
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.
Conformal perturbation theory and higher spin entanglement entropy on the torus
Shouvik Datta; Justin R. David; S. Prem Kumar
2014-12-12T23:59:59.000Z
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.
B. Kliem; T. Toeroek
2006-08-04T23:59:59.000Z
The expansion instability of a toroidal current ring in low-beta magnetized plasma is investigated. Qualitative agreement is obtained with experiments on spheromak expansion and with essential properties of solar coronal mass ejections, unifying the two apparently disparate classes of fast and slow coronal mass ejections.
Spherically symmetric conformal gravity and "gravitational bubbles"
V. A. Berezin; V. I. Dokuchaev; Yu. N. Eroshenko
2014-12-09T23:59:59.000Z
The general structure of the spherically symmetric solutions in the Weyl conformal gravity is described. The corresponding Bach equation are derived for the special type of metrics, which can be considered as the representative of the general class. The complete set of the pure vacuum solutions is found. It consists of two classes. The first one contains the solutions with constant two-dimensional curvature scalar of our specific metrics, and the representatives are the famous Robertson-Walker metrics. One of them we called the "gravitational bubbles", which is compact and with zero Weyl tensor. The second class is more general, with varying curvature scalar. We found its representative as the one-parameter family. It appears that it can be conformally covered by the thee-parameter Mannheim-Kazanas solution. We also investigated the general structure of the energy-momentum tensor in the spherical conformal gravity and constructed the vectorial equation that reveals clearly the same features of non-vacuum solutions. One of them, the metrics a la Vaidya, is explicitly written.
Neutrino oscillations in the general spherically symmetric gravitational field
Godunov, S. I., E-mail: sgodunov@itep.ru; Pastukhov, G. S., E-mail: grigoriypas@gmail.com [Institute for Theoretical and Experimental Physics (Russian Federation)
2012-09-15T23:59:59.000Z
The results for neutrino oscillations in the gravitational field described by the Schwarzschild metric are generalized to the general spherically symmetric gravitational field.
A spherical joint piston design for high speed diesel engines
Wiczynski, P.D. [Cummins Engine Co., Inc., Columbus, IN (United States); Mielke, S. [Kolbenschmidt AG, Neckarsulm (Germany); Conrow, R.
1996-09-01T23:59:59.000Z
A spherical joint piston and connecting rod have been developed through design proof-of-concept. The spherical joint allows piston rotation. The benefits of a rotating, symmetrical piston are: mechanical and thermal load symmetry, improved ring sealing and lubrication, and reduced bearing loads, scuffing, clearances and oil consumption. The assembly includes a squeeze cast, fiber reinforced aluminum spherical joint piston. Reinforcement is located in the piston bowl and skirt. The connecting rod consists of a spherical small end positioned on an elliptical cross-sectioned shank blended into a conventional big end. The assembly has operated at cylinder pressures exceeding of 24 MPa.
All spherically symmetric charged anisotropic solutions for compact star
Maurya, S K; Ray, Saibal
2015-01-01T23:59:59.000Z
In the present paper we develop an algorithm for all spherically symmetric anisotropic charged fluid distribution. Considering a new source function $\
All spherically symmetric charged anisotropic solutions for compact star
S. K. Maurya; Y. K. Gupta; Saibal Ray
2015-02-05T23:59:59.000Z
In the present paper we develop an algorithm for all spherically symmetric anisotropic charged fluid distribution. Considering a new source function $\
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
Dynamical friction force exerted on spherical bodies
O. Esquivel; B. Fuchs
2007-04-30T23:59:59.000Z
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
2015-06-14T23:59:59.000Z
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
2015-01-01T23:59:59.000Z
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.
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)
2013-11-15T23:59:59.000Z
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.
Electron cyclotron emission radiometer upgrade on the Joint European Torus (JET) tokamak
Luna, E. de la; Sanchez, J.; Tribaldos, V.; Conway, G.; Suttrop, W.; Fessey, J.; Prentice, R.; Gowers, C.; Chareau, J. M. [Asociacion EURATOM-CIEMAT para Fusion, CIEMAT, Madrid (Spain); IPP-EURATOM Association, Garching (Germany); EURATOM-UKAEA Fusion Associations, Culham Science Centre, Abingdon (United Kingdom); European Commission, Institute for Transuranium Elements, Karlsruhe (Germany)
2004-10-01T23:59:59.000Z
The capabilities of the Joint European Torus (JET) electron cyclotron emission (ECE) diagnostics have recently been extended with an upgrading of the heterodyne radiometer. The number of channels has been doubled to 96 channels, with a frequency separation corresponding to <1 cm for JET magnetic field gradient, and with a frequency response of 1 MHz. This enhancement has increased the radial coverage of the ECE electron temperature measurements in JET to approximately the full plasma column (limited at R>2.6 m for the X-mode due to harmonic overlap) at almost all magnetic field values used at JET (1.7 T
Cartolano, M. S.; Craig, D., E-mail: darren.craig@wheaton.edu [Wheaton College, Wheaton, Illinois 60187 (United States); Den Hartog, D. J.; Kumar, S. T. A.; Nornberg, M. D. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States) [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, Madison, Wisconsin 53706 (United States)
2014-01-15T23:59:59.000Z
The connection between impurity ion heating and other physical processes in the plasma is evaluated by studying variations in the amount of ion heating at reconnection events in the Madison Symmetric Torus (MST). Correlation of the change in ion temperature with individual tearing mode amplitudes indicates that the edge-resonant modes are better predictors for the amount of global ion heating than the core-resonant modes. There is also a strong correlation between ion heating and current profile relaxation. Simultaneous measurements of the ion temperature at different toroidal locations reveal, for the first time, a toroidal asymmetry to the ion heating in MST. These results present challenges for existing heating theories and suggest a stronger connection between edge-resonant tearing modes, current profile relaxation, and ion heating than has been previously thought.
First Studies of Pure Electron Plasmas in the Columbia Non-neutral Torus
Berkery, J. W.; Pedersen, T. S.; Kremer, J. P.; Lefrancois, R. G.; Marksteiner, Q. R.; Boozer, A. H. [Dept. of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027 (United States); Mynick, H. E.; Pomphrey, N.; Reiersen, W.; Dahlgreen, F. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Himura, H. [Kyoto Institute of Technology, Kyoto (Japan); Sarasola, X. [CIEMAT, Madrid (Spain)
2006-10-18T23:59:59.000Z
The first studies of pure electron plasmas confined on magnetic surfaces in the Columbia Non-neutral Torus are overviewed. The electron plasma is created by a thermionic emitter filament and similar filaments mounted on ceramic rods are used as Langmuir and emissive probes. The equilibrium density, temperature and potential profiles are experimentally measured. Numerical calculations of the equilibrium agree well with measurements and also predict a toroidal density variation of a factor of four. The confinement time is found to decrease with increased neutral pressure and emitter bias voltage, and it is presently limited to 20 ms by the insulated emitter and probe rods. A retractable electron emitter and external diagnostics will be used to determine the confinement time in the absence of rods. Ion driven instabilities are observed at high neutral pressure and low magnetic field strength. Further research of these instabilities will be carried out.
Group-Theoretical Quantization of 2+1 Geavity in the Metric-Torus Sector
P. Hajicek
1997-05-29T23:59:59.000Z
A symmetry based quantization method of reparametrization invariant systems is described; it will work for all systems that possess complete sets of perennials whose Lie algebras close and which generate a sufficiently large symmetry groups. The construction leads to a quantum theory including a Hilbert space, a complete system of operator observables and a unitary time evolution. The method is applied to the 2+1 gravity. The paper is restricted to the metric-torus sector, zero cosmological constant $\\Lambda$ and it makes strong use of the so-called homogeneous gauge; the chosen algebra of perennials is that due to Martin. Two frequent problems are tackled. First, the Lie algebra of perennials does not generate a group of symmetries. The notion of group completion of a reparametrization invariant system is introduced so that the group does act; the group completion of the physical phase space of our model is shown to add only some limit points to it so that the ranges of observables are not unduly changed. Second, a relatively large number of relations between observables exists; they are transferred to the quantum theory by the well-known methods due to Kostant and Kirillov. In this way, a uniqueness of the physical representation of some extension of Martin's algebra is shown. The Hamiltonian is defined by a systematic procedure due to Dirac; for the torus sector, the result coincides with that by Moncrief. The construction may be extensible to higher genera and non-zero $\\Lambda$ of the 2+1 gravity, because some complete sets of perennials are well-known and there are no obstructions to the closure of the algebra.
Static Solutions of Einstein's Equations with Spherical Symmetry
Iftikhar Ahmad; Maqsoom Fatima; Najam-ul-Basat
2014-05-02T23:59:59.000Z
The Schwarzschild solution is a complete solution of Einstein's field equations for a static spherically symmetric field. The Einstein's field equations solutions appear in the literature, but in different ways corresponding to different definitions of the radial coordinate. We attempt to compare them to the solutions with nonvanishing energy density and pressure. We also calculate some special cases with changes in spherical symmetry.
BROOKHAVEN NATIONAL LABORATORY'S HIGH FLUX BEAM REACTOR
Ohta, Shigemi
1 BROOKHAVEN NATIONAL LABORATORY'S HIGH FLUX BEAM REACTOR Compiled by S. M. Shapiro I. PICTORIAL with fiberglass insulation and a protective aluminum skin. The reactor vessel is shaped somewhat like a very large at the spherical end. It is located at the center of the reactor building and is surrounded by a lead and steel
PREPARED FOR THE U.S. DEPARTMENT OF ENERGY, UNDER CONTRACT DE-AC02-76CH03073
Spherical Torus Experiment (NSTX) by G.Taylor, P.C. Efthimion, B. Jones, B.P. LeBlanc, J.R. Wilson, J.B. Wilgen, G.L. Bell, T.S. Bigelow, R. Maingi, D.A. Rasmussen, R.W. Harvey, A.P. Smirnov, F. Paoletti, and S to the extraordinary electromagnetic mode on the National Spherical Torus Experiment (NSTX) G. Taylor, P.C. Efthimion
Small spherical tokamaks for nuclear applications
Peng, Y.K. M. [Oak Ridge National Lab, TN (United States); Abdou, M.A. [Univ. of California, Los Angeles, CA (United States)] [and others
1994-12-31T23:59:59.000Z
Recent experimental tests have produced encouraging data concerning plasma properties in the spherical tokamak (ST), a tokamak configuration with the aspect ratio (R{sub 0}/a) significantly below two. Here R{sub 0} and a are the major and minor radii, respectively. Large gains in plasma performance and external field utilization are projected as R{sub 0}/a is reduced from the normal range (2.5 and higher) to 1.5 or less. This introduces the possibility for small, D-T fueled, driven, steady-state ST devices capable of producing a fusion neutron wall loading in the range of 0.5 to 2.0 MW/m{sup 2}. The cases with neutron wall loads in the range of 1 to 2 MW/m{sup 2} could serve as the fusion volume neutron source for testing full-function nuclear blankets of significant sizes (about 1 m by 1 m facing the plasma). Those in the range of 0.5 to 1 MW/m{sup 2} could serve as the fusion driver for transmutation of nuclear wastes. Important plasma physics, technology, and engineering issues in implementing such small fusion devices will be identified and discussed, together with the potential contributions by this line of research to reducing time and cost of fusion energy development.
Brown, Michael R.
A compact torus (CT), or spheromak, is a toroidal mag- netofluid configuration in which plasma is cot tokamak by the Caltech Spheromak Ijec- tion experiment to study helicity injection and refueling,3
Stephan Gekle; Jörg Main; Thomas Bartsch; T. Uzer
2006-10-02T23:59:59.000Z
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.
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)
2013-10-20T23:59:59.000Z
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.
An axisymmetric hydrodynamical model for the torus wind in AGN. II: X-ray excited funnel flow
A. Dorodnitsyn; T. Kallman; D. Proga
2008-06-23T23:59:59.000Z
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.
An axisymmetric hydrodynamical model for the torus wind in AGN. II: X-ray excited funnel flow
Dorodnitsyn, A; Proga, D
2008-01-01T23:59:59.000Z
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...
BACKSCATTERING BY NON-SPHERICAL NATURAL PARTICLES: INSTRUMENT DEVELOPMENT, IOP'S,
Boss, Emmanuel S.
of the proposed instrument. Figure 1: Engineering view of the self-contained battery powered instrument. In light-spherical effects on backscatter. b. Characterization of scattering from terrigenous and biological size-sorted non
Water adsorption on aggregates of spherical aerosol nano particles
Nie, Chu
2005-11-01T23:59:59.000Z
A three dimensional integral equation is developed in order to compute water adsorption onto aggregates of spherical aerosol nano particles. The integral equation is derived from molecular density functional theory, with a weighted density...
Elastic–Plastic Spherical Contact Modeling Including Roughness Effects
Li, L.; Etsion, I.; Talke, F. E.
2010-01-01T23:59:59.000Z
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
Spherically Symmetric Considerations for a Higher Order Theory of Gravitation
S. N. Pandey; B. K. Sinha
2009-11-03T23:59:59.000Z
A higher order theory of gravitation is considered which is obtained by modifying Einstein field equations. The Lagrange used to modify this in the form a polynomial in (scalar curvature) R. In this equation we have studied spherical symmetric metric.
Free energy and complexity of spherical bipartite models
Antonio Auffinger; Wei-Kuo Chen
2014-05-09T23:59:59.000Z
We investigate both free energy and complexity of the spherical bipartite spin glass model. We first prove a variational formula in high temperature for the limiting free energy based on the well-known Crisanti-Sommers representation of the mixed p-spin spherical model. Next, we show that the mean number of local minima at low levels of energy is exponentially large in the size of the system and we derive a bound on the location of the ground state energy.
Reusch, J. A.; Anderson, J. K.; Eilerman, S. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Belykh, V.; Polosatkin, S. [Budker Institute of Nuclear Physics SB RAS, Novosibirsk (Russian Federation); Liu, D. [University of California-Irvine, Irvine, California 92697 (United States); Fiksel, G. [University of Rochester, Rochester, New York 14623 (United States)
2012-10-15T23:59:59.000Z
A new E Parallel-To B neutral particle analyzer, which has recently been installed on Madison Symmetric Torus (MST) reversed-field pinch (RFP), has now been calibrated, allowing the measurement of the fast ion density and energy distribution. This diagnostic, dubbed the advanced neutral particle analyzer (ANPA), can simultaneously produce time resolved measurements of the efflux of both hydrogen and deuterium ions from the plasma over a 35 keV energy range with an energy resolution of 2-4 keV and a time resolution of 10 {mu}s. These capabilities are needed to measure both majority ion heating that occurs during magnetic reconnection events in MST and the behavior of the fast ions from the 1 MW hydrogen neutral beam injector on MST. Calibration of the ANPA was performed using a custom ion source that resides in the flight tube between the MST and the ANPA. In this work, the ANPA will be described, the calibration procedure and results will be discussed, and initial measurements of the time evolution of 25 keV neutral beam injection-born fast ions will be presented.
Plasma behaviour at high beta and high density in the Madison Symmetric Torus RFP
Wyman, M. [University of Wisconsin, Madison; Chapman, B. E. [University of Wisconsin, Madison; Ahn, J. W. [University of Wisconsin, Madison; Almagri, A. F. [University of Wisconsin, Madison; Anderson, J. [University of Wisconsin, Madison; Bonomo, F. [Consorzio RFX, Italy; Bower, D L [University of California, Los Angeles; Combs, Stephen Kirk [ORNL; Craig, D. [University of Wisconsin, Madison; Foust, Charles R [ORNL
2009-01-01T23:59:59.000Z
Pellet fuelling of improved confinement Madison Symmetric Torus (MST) plasmas has resulted in high density and high plasma beta. The density in improved confinement discharges has been increased fourfold, and a record plasma beta (beta(tot) = 26%) for the improved confinement reversed-field pinch (RFP) has been achieved. At higher beta, a new regime for instabilities is accessed in which local interchange and global tearing instabilities are calculated to be linearly unstable, but experimentally, no severe effect, e. g., a disruption, is observed. The tearing instability, normally driven by the current gradient, is driven by the pressure gradient in this case, and there are indications of increased energy transport ( as compared with low-density improved confinement). Pellet fuelling is also compared with enhanced edge fuelling of standard confinement RFP discharges for the purpose of searching for a density limit in MST. In standard-confinement discharges, pellet fuelling peaks the density profile where edge fuelling cannot, but transport appears unchanged. For a limited range of plasma current, MST discharges with edge fuelling are constrained to a maximum density corresponding to the Greenwald limit. This limit is surpassed in pellet-fuelled improved confinement discharges.
Confinement of pure electron plasmas in the Columbia Non-neutral Torus
Berkery, John W.; Pedersen, Thomas Sunn; Kremer, Jason P.; Marksteiner, Quinn R.; Lefrancois, Remi G.; Hahn, Michael S.; Brenner, Paul W. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)
2007-06-15T23:59:59.000Z
The Columbia Non-neutral Torus (CNT) [T. S. Pedersen, J. P. Kremer, R. G. Lefrancois, Q. Marksteiner, N. Pomphrey, W. Reiersen, F. Dahlgreen, and X. Sarasola, Fusion Sci. Technol. 50, 372 (2006)] is a stellarator used to study non-neutral plasmas confined on magnetic surfaces. A detailed experimental study of confinement of pure electron plasmas in CNT is described here. Electrons are introduced into the magnetic surfaces by placing a biased thermionic emitter on the magnetic axis. As reported previously, the insulated rods holding this and other emitter filaments contribute to the radial transport by charging up negatively and creating ExB convective transport cells. A model for the rod-driven transport is presented and compared to the measured transport rates under a number of different conditions, finding good agreement. Neutrals also drive transport, and by varying the neutral pressure in the experiment, the effects of rod-driven and neutral-driven transport are separated. The neutral-driven electron loss rate scales linearly with neutral pressure. The neutral driven transport, presumably caused by electron-neutral collisions, is much greater than theoretical estimates for neoclassical diffusion in a classical stellarator with strong radial electric fields. In fact the confinement time is on the order of the electron-neutral collision time. Ion accumulation, electron attachment, and other effects are considered, but do not explain the observed transport rates.
Method to produce large, uniform hollow spherical shells
Hendricks, C.D.
1983-09-26T23:59:59.000Z
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.
Collective neutrino oscillations in non-spherical geometry
Basudeb Dasgupta; Amol Dighe; Alessandro Mirizzi; Georg G. Raffelt
2008-05-21T23:59:59.000Z
The rich phenomenology of collective neutrino oscillations has been studied only in one-dimensional or spherically symmetric systems. Motivated by the non-spherical example of coalescing neutron stars, presumably the central engines of short gamma-ray bursts, we use the Liouville equation to formulate the problem for general source geometries. Assuming the neutrino ensemble displays self-maintained coherence, the problem once more becomes effectively one-dimensional along the streamlines of the overall neutrino flux. This approach for the first time provides a formal definition of the ``single-angle approximation'' frequently used for supernova neutrinos and allows for a natural generalization to non-spherical geometries. We study the explicit example of a disk-shaped source as a proxy for coalescing neutron stars.
CHARACTERIZATION OF CYCLED SPHERICAL RESORCINOL-FORMALDEHYDE ION EXCHANGE RESIN
Nash, C.; Duignan, M.
2010-02-23T23:59:59.000Z
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)
2013-11-15T23:59:59.000Z
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.
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)
2014-06-15T23:59:59.000Z
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.
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
2013-08-27T23:59:59.000Z
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.
Thermochemical structures within a spherical mantle: Superplumes or piles?
Zhong, Shijie
Thermochemical structures within a spherical mantle: Superplumes or piles? Allen K. Mc interpreted as being either piles or superplumes of dense material. We perform numerical modeling a dense chemical component into a small number of isolated, rounded piles or superplumes of material. We
Decay Rates for Spherical Scalar Waves in the Schwarzschild Geometry
Johann Kronthaler
2007-09-24T23:59:59.000Z
The Cauchy problem is considered for the scalar wave equation in the Schwarzschild geometry. Using an integral spectral representation we derive the exact decay rate for solutions of the Cauchy problem with spherical symmetric initial data, which is smooth and compactly supported outside the event horizon.
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)
2014-02-07T23:59:59.000Z
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.
Møller energy of the nonstatic spherically symmetric metrics
S. S. Xulu
2000-10-19T23:59:59.000Z
The energy distribution in the most general nonstatic spherically symmetric space-time is obtained using M{\\o}ller's energy-momentum complex. This result is compared with the energy expression obtained by using the energy-momentum complex of Einstein. Some examples of energy distributions in different prescriptions are discussed.
Shell Crossing Singularities in Quasi-Spherical Szekeres Models
Subenoy Chakraborty; Ujjal Debnath
2007-12-16T23:59:59.000Z
We investigate the occurrence of shell crossing singularities in quasi-spherical Szekeres dust models with or without a cosmological constant. We study the conditions for shell crossing singularity both from physical and geometrical point of view and they are in agreement.
Casimir energy of a spherical shell in $?-$Minkowski spacetime
Hyeong-Chan Kim; Chaiho Rim; Jae Hyung Yee
2008-12-12T23:59:59.000Z
We study the Casimir energy of a spherical shell of radius $a$ in $\\kappa$-Minkowski spacetime for a complex field with an asymmetric ordering and obtain the energy up to $O(1/\\kappa^2)$. We show that the vacuum breaks particle and anti-particle symmetry if one requires the spectra to be consistent with the blackbody radiation at the commutative limit.
The Einstein-Vlasov-Maxwell(EVM) System with Spherical Symmetry
P. Noundjeu
2005-05-23T23:59:59.000Z
We look for the global in time solution of the Cauchy problem corresponding to the asymptotically flat spherically symmetric EVM system with small initial data. Using an estimate, we also prove that if solution of the system stated above develops a singularity at all time, then the first one has to appear at the center of symmetry.
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
ABAREX: A neutron spherical optical-statistical model code
Lawson, R.D.
1992-06-01T23:59:59.000Z
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 radon transforms and mathematical problems of thermoacoustic tomography
Ambartsoumian, Gaik
2009-06-02T23:59:59.000Z
The spherical Radon transform (SRT) integrates a function over the set of all spheres with a given set of centers. Such transforms play an important role in some newly developing types of tomography as well as in several areas of mathematics...
No Scalar Hair Theorem for a Charged Spherical Black Hole
N. Banerjee; S. Sen
1998-08-11T23:59:59.000Z
This paper consolidates noscalar hair theorem for a charged spherically symmetric black hole in four dimension in general relativity as well as in all scalar tensor theories, both minimally and nonminimally coupled, when the effective Newtonian constant of gravity is positive. However, there is an exception when the matter field itself is coupled to the scalar field, such as in dilaton gravity.
Collapse of non-spherically symmetric scalar field distributions
Koyel Ganguly; Narayan Banerjee
2011-05-23T23:59:59.000Z
In the present work the collapse scenario of some exact non-spherical models with a minimally coupled scalar field is studied. Scalar field collapse with planar as well as toroidal, cylindrical and pseudoplanar symmetries have been investigated. It is shown that the scalar field may have collapsing modes even if it has the equation of state corresponding to that of a dark energy.
A. -C. Donea; R. J. Protheroe
2002-02-04T23:59:59.000Z
The radiation fields external to the jets and originating from within a few parsecs from the black hole, are discussed in this paper. They are the direct radiation from an accretion disk in symbiosis with jets, the radiation field from the broad line region (BLR) surrounding the accretion disk, and the infrared radiation from a dusty torus. The jet/disk symbiosis modifies the energetics in the central parsec of AGN such that for a given accretion rate, a powerful jet would occur at the expense of the disk luminosity, and consequently the disk would less efficiently ionize the BRL clouds or heat the dust in the torus, thereby affecting potentially important target photon fields for interactions of gamma-rays, accelerated electrons and protons along the jet. Motivated by unification schemes of active galactic nuclei, we briefly review the evidence for the existence of broad line regions and small-scale dust tori in BL Lacs and Fanaroff-Riley Class I (FR-I) radio galaxies. We propose that an existing jet-accretion disk symbiosis can be extrapolated to provide a large scale-symbiosis between other important dusty constituents of the blazar/FR-I family. In the present paper, we discuss in the context of this symbiosis interactions of GeV and TeV gamma-rays produced in the jet with the various radiation fields external to the jet in quasars and blazars, taking account the anisotropy of the radiation.
Etheridge, A M
2011-01-01T23:59:59.000Z
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
2015-06-19T23:59:59.000Z
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.
2010-07-14T23:59:59.000Z
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 sphere. The sphere acts as a...
Patterns of convection in rotating spherical R Simitev and F H Busse
Simitev, Radostin D
Patterns of convection in rotating spherical shells R Simitev and F H Busse Institute of Physics of rotating spherical shells. For recent reviews we refer to the papers by Zhang and Busse [23] and Busse [6
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
Luciano Rezzolla; Luca Baiotti; Bruno Giacomazzo; David Link; Jose A. Font
2010-05-13T23:59:59.000Z
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.
Free falling and rising of spherical and angular particles
Rahmani, M., E-mail: mona.rahmani@ifpen.fr; Wachs, A., E-mail: anthony.wachs@ifpen.fr [Fluid Mechanics Department, IFP Energies nouvelles, Etablissement de Lyon, 69360 Solaize (France)
2014-08-15T23:59:59.000Z
Direct numerical simulations of freely falling and rising particles in an infinitely long domain, with periodic lateral boundary conditions, are performed. The focus is on characterizing the free motion of cubical and tetrahedral particles for different Reynolds numbers, as an extension to the well-studied behaviour of freely falling and rising spherical bodies. The vortical structure of the wake, dynamics of particle movement, and the interaction of the particle with its wake are studied. The results reveal mechanisms of path instabilities for angular particles, which are different from those for spherical ones. The rotation of the particle plays a more significant role in the transition to chaos for angular particles. Following a framework similar to that of Mougin and Magnaudet [“Wake-induced forces and torques on a zigzagging/spiralling bubble,” J. Fluid Mech. 567, 185–194 (2006)], the balance of forces and torques acting on particles is discussed to gain more insight into the path instabilities of angular particles.
Global energy conservation in nonlinear spherical characteristic evolutions
Barreto, W
2014-01-01T23:59:59.000Z
Associated to the subgroup unique and four--parametric of translations, normal to the Bondi--Metzner--Sachs group, there exists a generator of the temporal translation asymptotic symmetry. {Such a descriptor of the motion along the conformal orbit near null infinity is propagated to finite regions. This allow us to observe the global energy conservation even in extreme situations near critical behavior of the massless scalar field collapse in spherical symmetry.
Critical adsorption on non-spherical colloidal particles
S. Kondrat; L. Harnau; S. Dietrich
2007-05-24T23:59:59.000Z
We consider a non-spherical colloidal particle immersed in a fluid close to its critical point. The temperature dependence of the corresponding order parameter profile is calculated explicitly. We perform a systematic expansion of the order parameter profile in powers of the local curvatures of the surface of the colloidal particle. This curvature expansion reduces to the short distance expansion of the order parameter profile in the case that the solvent is at the critical composition.
Self-similar spherical shock solution with sustained energy injection
V. I. Dokuchaev
2002-09-20T23:59:59.000Z
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 $k\
Global energy conservation in nonlinear spherical characteristic evolutions
W. Barreto
2014-04-20T23:59:59.000Z
Associated to the unique 4-parametric subgroup of translations, normal to the Bondi-Metzner-Sachs group, there exists a generator of the temporal translation asymptotic symmetry. Such a descriptor of the motion along the conformal orbit near null infinity is propagated to finite regions. This allows us to observe the global energy conservation even in extreme situations near the critical behavior of the massless scalar field collapse in spherical symmetry.
TDHF fusion calculations for spherical+deformed systems
A. S. Umar; V. E. Oberacker
2006-04-04T23:59:59.000Z
We outline a formalism to carry out TDHF calculations of fusion cross sections for spherical + deformed nuclei. The procedure incorporates the dynamic alignment of the deformed nucleus into the calculation of the fusion cross section. The alignment results from multiple E2/E4 Coulomb excitation of the ground state rotational band. Implications for TDHF fusion calculations are discussed. TDHF calculations are done in an unrestricted three-dimensional geometry using modern Skyrme force parametrizations.
Energy of spherically symmetric spacetimes on regularizing teleparallelism
G. G. L. Nashed
2010-04-11T23:59:59.000Z
We calculate the total energy of an exact spherically symmetric solutions, i.e., Schwarzschild and Reissner Nordstr$\\ddot{o}$m, using the gravitational energy-momentum 3-form within the tetrad formulation of general relativity. We explain how the effect of the inertial makes the total energy unphysical! Therefore, we use the covariant teleparallel approach which makes the energy always physical one. We also show that the inertial has no effect on the calculation of momentum.
Spherically Symmetric Solutions to Fourth-Order Theories of Gravity
T. Clifton
2006-11-10T23:59:59.000Z
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.
A New Result on the Dynamical Symmetry of Spherical Collapse
Subenoy Chakraborty; Asit Banerjee; Ujjal Debnath
2006-02-27T23:59:59.000Z
A dynamical symmetry for spherical collapse has been studied using a linear transformation of the initial data set (mass and kinetic energy function) and the area radius. With proper choice of the initial area radius, the evolution as well as the physical parameters namely energy density and shear remain invariant both initially and at any time instant. Finally, it is found that the final outcome of collapse depends on the initial choice of the area radius.
Spherical Resorcinol-Formaldehyde Synthesis by Inverse Suspension Polymerization
Ray, Robert J.; Scrivens, Walter A.; Nash, Charles
2005-10-21T23:59:59.000Z
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.
Spherical codes, maximal local packing density, and the golden ratio
A. B. Hopkins; F. H. Stillinger; S. Torquato
2010-03-18T23:59:59.000Z
The densest local packing (DLP) problem in d-dimensional Euclidean space Rd involves the placement of N nonoverlapping spheres of unit diameter near an additional fixed unit-diameter sphere such that the greatest distance from the center of the fixed sphere to the centers of any of the N surrounding spheres is minimized. Solutions to the DLP problem are relevant to the realizability of pair correlation functions for packings of nonoverlapping spheres and might prove useful in improving upon the best known upper bounds on the maximum packing fraction of sphere packings in dimensions greater than three. The optimal spherical code problem in Rd involves the placement of the centers of N nonoverlapping spheres of unit diameter onto the surface of a sphere of radius R such that R is minimized. It is proved that in any dimension, all solutions between unity and the golden ratio to the optimal spherical code problem for N spheres are also solutions to the corresponding DLP problem. It follows that for any packing of nonoverlapping spheres of unit diameter, a spherical region of radius less than or equal to the golden ratio centered on an arbitrary sphere center cannot enclose a number of sphere centers greater than one more than the number that can be placed on the region's surface.
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)
2002-01-01T23:59:59.000Z
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.
Design of interferometer system for Keda Torus eXperiment using terahertz solid-state diode sources
Xie, Jinlin, E-mail: jlxie@ustc.edu.cn; Wang, Haibo; Li, Hong; Lan, Tao; Liu, Adi; Liu, Wandong; Yu, Changxuan [School of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Ding, Weixing [School of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); University of California-Los Angeles, P. O. Box 957099, Los Angeles, California 90095-7099 (United States)
2014-11-15T23:59:59.000Z
A solid-state source based terahertz (THz) interferometer diagnostic system has been designed and characterized for the Keda Torus eXperiment (KTX). The THz interferometer utilizes the planar diodes based frequency multiplier (X48) to provide the probing beam at fixed frequency 0.650 THz, and local oscillator is provided by an independent solid-state diode source with tunable frequency (0.650 THz +/? 10 MHz). Both solid-state sources have approximately 1 mW power. The planar-diode mixers optimized for high sensitivity, ?750 mV/mW, are used in the heterodyne detection system, which permits multichannel interferometer on KTX with a low phase noise. A sensitivity of
Basic Routines for the Rank2k Update: 2D Torus vs Reconfigurable Network
Desprez, Frédéric
by the National Science Foundation Science and Technology Center Cooperative Agreement No. CCR8809615, CNRS Center Cooperative Agreement CCR8809615, the DARPA and ARO under contract DAAL0391C0047, PRC C 3 , CNRSNSF grant 950.223/07, Archipel SA and MRE under grant 974, and DRET. 1 #12; interconnection
FOR APPLICATION IN THE ETE SPHERICAL TOKAMAKAPPLICATION IN THE ETE SPHERICAL TOKAMAK Luis Filipe de F. P. Wiltgen tokamak based on Artificial Neural Networks (tokamak based on Artificial Neural Networks (ANNANN).). ETEETE is ais a low aspect ratio tokamak that should operate with highly elongated plasmas, which
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 ...
The 2m <= r property of spherically symmetric static spacetimes
Marc Mars; M. M. Martin-Prats; Jose M. M. Senovilla
2002-02-01T23:59:59.000Z
We prove that all spherically symmetric static spacetimes which are both regular at r=0 and satisfying the single energy condition rho + p_r + p_t >= 0 cannot contain any black hole region (equivalently, they must satisfy 2m/r <= 1 everywhere). This result holds even when the spacetime is allowed to contain a finite number of matching hypersurfaces. This theorem generalizes a result by Baumgarte and Rendall when the matter contents of the space-time is a perfect fluid and also complements their results in the general non-isotropic case.
Spherical thin-shell wormholes and modified Chaplygin gas
Sharif, M.; Azam, M., E-mail: msharif.math@pu.edu.pk, E-mail: azammath@gmail.com [Department of Mathematics, University of the Punjab, Quaid-e-Azam Campus, Lahore-54590 (Pakistan)
2013-05-01T23:59:59.000Z
The purpose of this paper is to construct spherical thin-shell wormhole solutions through cut and paste technique and investigate the stability of these solutions in the vicinity of modified Chaplygin gas. The Darmois-Israel formalism is used to formulate the stresses of the surface concentrating the exotic matter. We explore the stability of the wormhole solutions by using the standard potential method. We conclude that there exist more stable as well as unstable solutions than the previous study with generalized Chaplygin gas [19].
Casimir interactions of an object inside a spherical metal shell
Saad Zaheer; Sahand Jamal Rahi; Thorsten Emig; Robert L. Jaffe
2009-11-03T23:59:59.000Z
We investigate the electromagnetic Casimir interactions of an object contained within an otherwise empty, perfectly conducting spherical shell. For a small object we present analytical calculations of the force, which is directed away from the center of the cavity, and the torque, which tends to align the object opposite to the preferred alignment outside the cavity. For a perfectly conducting sphere as the interior object, we compute the corrections to the proximity force approximation (PFA) numerically. In both cases the results for the interior configuration match smoothly onto those for the corresponding exterior configuration.
A non-conforming 3D spherical harmonic transport solver
Van Criekingen, S. [Commissariat a l'Energie Atomique CEA-Saclay, DEN/DM2S/SERMA/LENR Bat 470, 91191 Gif-sur-Yvette, Cedex (France)
2006-07-01T23:59:59.000Z
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)
On the vacuum energy of a spherical plasma shell
M. Bordag; N. Khusnutdinov
2008-01-14T23:59:59.000Z
We consider the vacuum energy of the electromagnetic field interacting with a spherical plasma shell together with a model for the classical motion of the shell. We calculate the heat kernel coefficients, especially that for the TM mode, and carry out the renormalization by redefining the parameters of the classical model. It turns out that this is possible and results in a model, which in the limit of the plasma shell becoming an ideal conductor reproduces the vacuum energy found by Boyer in 1968.
Casimir energy for spherical shell in Schwarzchild black hole background
M. R. Setare; M. B. Altaie
2003-08-28T23:59:59.000Z
In this paper, we consider the Casimir energy of massless scalar field which satisfy Dirichlet boundary condition on a spherical shell. Outside the shell, the spacetime is assumed to be described by the Schwarzschild metric, while inside the shell it is taken to be the flat Minkowski space. Using zeta function regularization and heat kernel coefficients we isolate the divergent contributions of the Casimir energy inside and outside the shell, then using the renormalization procedure of the bag model the divergent parts are cancelled, finally obtaining a renormalized expression for the total Casimir energy.
Spherical Accretion onto Neutron Stars Revisited: Are Hot Solutions Possible ?
Roberto Turolla; Luca Zampieri; Monica Colpi; Aldo Treves
1994-02-21T23:59:59.000Z
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.
Angular Momentum Mixing in a Non-spherical Color Superconductor
Bo Feng; Defu Hou; Hai-cang Ren
2007-11-28T23:59:59.000Z
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.
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
2015-01-01T23:59:59.000Z
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.
Spherical Wave Propagation in a Nonlinear Elastic Medium
Korneev, Valeri A.
2009-07-01T23:59:59.000Z
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.
Numerical Analysis of Spherically Convergent Rayleigh-Taylor Experiments
Galmiche, D.; Cherfils, C.; Glendinning, S.G.; Remington, B.A.; Richard, A.
2000-05-17T23:59:59.000Z
In the frame of a CEA/US DOE collaboration, radiation driven spherically convergent experiments were performed on the Nova laser in order m measure the Rayleigh-Taylor growth at the ablation front. Numerical simulations using the 2D Lagrangian code FCI2 have correctly reproduced experiments in moderate convergent geometry. [C. Cherfils et al., PRL 83, 5507 (1999)]. Experiments have addressed convergence ratios up to 4 by considering larger capsules, larger hohlraum and longer laser pulses [S.G. Glendinning et al., to be published in Physics of Plasmas]. Numerical analysis of these high convergence implosions is presented, and the effect of convergence on the Rayleigh-Taylor growth is investigated.
Geometrodynamics in a spherically symmetric, static crossflow of null dust
Zsolt Horváth; Zoltán Kovács; László Á. Gergely
2006-10-12T23:59:59.000Z
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
2006-01-01T23:59:59.000Z
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.
Large scale properties in turbulent spherically symmetric accretion
Arnab K. Ray; J. K. Bhattacharjee
2005-10-05T23:59:59.000Z
The role of turbulence in a spherically symmetric accreting system has been studied on very large spatial scales of the system. This is also a highly subsonic flow region and here the accreting fluid has been treated as nearly incompressible. It has been shown here that the coupling of the mean flow and the turbulent fluctuations, gives rise to a scaling relation for an effective "turbulent viscosity". This in turn leads to a dynamic scaling for sound propagation in the accretion process. As a consequence of this scaling, the sonic horizon of the transonic inflow solution is shifted inwards, in comparison with the inviscid flow.
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Locked modes and magnetic field errors in the Madison Symmetric Torus
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Jantzen, Robert T
2012-01-01T23:59:59.000Z
In considering the mathematical problem of describing the geodesics on a torus or any other surface of revolution, there is a tremendous advantage in conceptual understanding that derives from taking the point of view of a physicist by interpreting parametrized geodesics as the paths traced out in time by the motion of a point in the surface, identifying the parameter with the time. Considering energy levels in an effective potential for the reduced motion then proves to be an extremely useful tool in studying the behavior and properties of the geodesics. The same approach can be easily tweaked to extend to both the nonrelativistic and relativistic Kepler problems. The spectrum of closed geodesics on the torus is analogous to the quantization of energy levels in models of atoms.
Robert T. Jantzen
2012-12-26T23:59:59.000Z
In considering the mathematical problem of describing the geodesics on a torus or any other surface of revolution, there is a tremendous advantage in conceptual understanding that derives from taking the point of view of a physicist by interpreting parametrized geodesics as the paths traced out in time by the motion of a point in the surface, identifying the parameter with the time. Considering energy levels in an effective potential for the reduced motion then proves to be an extremely useful tool in studying the behavior and properties of the geodesics. The same approach can be easily tweaked to extend to both the nonrelativistic and relativistic Kepler problems. The spectrum of closed geodesics on the torus is analogous to the quantization of energy levels in models of atoms.
Spherically symmetric gravitating shell as a reparametrization invariant system
P. Hajicek; Berne
1997-08-18T23:59:59.000Z
The subject of this paper are spherically symmetric thin shells made of barotropic ideal fluid and moving under the influence of their own gravitational field as well as that of a central black hole; the cosmological constant is assumed to be zero. The general super-Hamiltonian derived in a previous paper is rewritten for this spherically symmetric special case. The dependence of the resulting action on the gravitational variables is trivialized by a transformation due to Kucha\\v{r}. The resulting variational principle depends only on shell variables, is reparametrization invariant, and includes both first- and second-class constraints. Several equivalent forms of the constrained system are written down. Exclusion of the second-class constraints leads to a super-Hamiltonian which appears to overlap with that by Ansoldi et al. in a quarter of the phase space. As Kucha\\v{r}' variables are singular at the horizons of both Schwarzschild spacetimes inside and outside the shell, the dynamics is first well-defined only inside of 16 disjoint sectors. The 16 sectors are, however, shown to be contained in a single, connected symplectic manifold and the constraints are extended to this manifold by continuity. Poisson bracket between no two independent spacetime coordinates of the shell vanish at any intersection of two horizons.
Numerical Relativity in Spherical Polar Coordinates: Off-center Simulations
Thomas W. Baumgarte; Pedro J. Montero; Ewald Müller
2015-06-03T23:59:59.000Z
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.
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)
2010-03-15T23:59:59.000Z
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.
Rheotaxis of spherical active particles near a planar wall
W. E. Uspal; M. N. Popescu; S. Dietrich; M. Tasinkevych
2015-02-16T23:59:59.000Z
For active particles the interplay between the self-generated hydrodynamic flow and an external shear flow, especially near bounding surfaces, can result in a rich behavior of the particles not easily foreseen from the consideration of the active and external driving mechanisms in isolation. For instance, under certain conditions, the particles exhibit "rheotaxis," i.e., they align their direction of motion with the plane of shear spanned by the direction of the flow and the normal of the bounding surface and move with or against the flow. To date, studies of rheotaxis have focused on elongated particles (e.g., spermatozoa), for which rheotaxis can be understood intuitively in terms of a "weather vane" mechanism. Here we investigate the possibility that spherical active particles, for which the "weather vane" mechanism is excluded due to the symmetry of the shape, may nevertheless exhibit rheotaxis. Combining analytical and numerical calculations, we show that, for a broad class of spherical active particles, rheotactic behavior may emerge via a mechanism which involves "self-trapping" near a hard wall owing to the active propulsion of the particles, combined with their rotation, alignment, and "locking" of the direction of motion into the shear plane. In this state, the particles move solely up- or downstream at a steady height and orientation.
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Electrostatic self-energy in static black holes with spherical symmetry
B. Linet
2000-06-28T23:59:59.000Z
We determine the expression of the electrostatic self-energy for a point charge in the static black holes with spherical symmetry having suitable properties
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Brane solutions of a spherical sigma model in six dimensions
Hyun Min Lee; Antonios Papazoglou
2004-11-16T23:59:59.000Z
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.
Reactive self-heating model of aluminum spherical nanoparticles
Karen S. Martirosyan; Maxim Zyskin
2012-12-17T23:59:59.000Z
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
2012-01-01T23:59:59.000Z
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.
Regularization of spherical and axisymmetric evolution codes in numerical relativity
Milton Ruiz; Miguel Alcubierre; Dario Nunez
2007-09-11T23:59:59.000Z
Several interesting astrophysical phenomena are symmetric with respect to the rotation axis, like the head-on collision of compact bodies, the collapse and/or accretion of fields with a large variety of geometries, or some forms of gravitational waves. Most current numerical relativity codes, however, can not take advantage of these symmetries due to the fact that singularities in the adapted coordinates, either at the origin or at the axis of symmetry, rapidly cause the simulation to crash. Because of this regularity problem it has become common practice to use full-blown Cartesian three-dimensional codes to simulate axi-symmetric systems. In this work we follow a recent idea idea of Rinne and Stewart and present a simple procedure to regularize the equations both in spherical and axi-symmetric spaces. We explicitly show the regularity of the evolution equations, describe the corresponding numerical code, and present several examples clearly showing the regularity of our evolutions.
On the gravitational self-energy of a spherical shell
G. Dillon
2013-03-14T23:59:59.000Z
According to Einstein's mass-energy equivalence, a body with a given mass extending in a large region of space, will get a smaller mass when confined into a smaller region, because of its own gravitational energy. The classical self-energy problem has been studied in the past in connection with the renormalization of a charged point particle. Still exact consistent solutions have not been thoroughly discussed in the simpler framework of Newtonian gravity. Here we exploit a spherical symmetrical shell model and find two possible solutions, depending on some additional assumption. The first solution goes back to Arnowitt, Deser and Misner (1960). The second is new and yields a new vanishingly small value (10^-55 cm) for the classical electron radius.
Self Tuning Scalar Fields in Spherically Symmetric Spacetimes
Appleby, Stephen
2015-01-01T23:59:59.000Z
We search for self tuning solutions to the Einstein-scalar field equations for the simplest class of `Fab-Four' models with constant potentials. We first review the conditions under which self tuning occurs in a cosmological spacetime, and by introducing a small modification to the original theory - introducing the second and third Galileon terms - show how one can obtain de Sitter states where the expansion rate is independent of the vacuum energy. We then consider whether the same self tuning mechanism can persist in a spherically symmetric inhomogeneous spacetime. We show that there are no asymptotically flat solutions to the field equations in which the vacuum energy is screened, other than the trivial one (Minkowski space). We then consider the possibility of constructing Schwarzschild de Sitter spacetimes for the modified Fab Four plus Galileon theory. We argue that the only model that can successfully screen the vacuum energy in both an FLRW and Schwarzschild de Sitter spacetime is one containing `John...
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)
2013-10-01T23:59:59.000Z
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.
Anisotropic diffusion of spherical particles in closely confining microchannels
Dettmer, Simon L; Misiunas, Karolis; Keyser, Ulrich F
2014-01-01T23:59:59.000Z
We present here the measurement of the diffusivity of spherical particles closely confined by narrow microchannels. Our experiments yield a 2D map of the position-dependent diffusion coefficients parallel and perpendicular to the channel axis with a resolution down to 129 nm. The diffusivity was measured simultaneously in the channel interior, the bulk reservoirs as well as the channel entrance region. In the channel interior we found strongly anisotropic diffusion. While the perpendicular diffusion coefficient close to the confining walls decreased down to approximately 25 % of the value on the channel axis, the parallel diffusion coefficient remained constant throughout the entire channel width. In addition to the experiment, we performed finite element simulations for the diffusivity in the channel interior and found good agreement with the measurements. Our results reveal the distinctive influence of strong confinement on Brownian motion which is of significance to microfluidics as well as quantitative mo...
Exit time distribution in spherically symmetric two-dimensional domains
Rupprecht, J -F; Grebenkov, D S; Voituriez, R
2014-01-01T23:59:59.000Z
The distribution of exit times is computed for a Brownian particle in spherically symmetric two- dimensional domains (disks, angular sectors, annuli) and in rectangles that contain an exit on their boundary. The governing partial differential equation of Helmholtz type with mixed Dirichlet- Neumann boundary conditions is solved analytically. We propose both an exact solution relying on a matrix inversion, and an approximate explicit solution. The approximate solution is shown to be exact for an exit of vanishing size and to be accurate even for large exits. For angular sectors, we also derive exact explicit formulas for the moments of the exit time. For annuli and rectangles, the approximate expression of the mean exit time is shown to be very accurate even for large exits. The analysis is also extended to biased diffusion. Since the Helmholtz equation with mixed boundary conditions is encountered in microfluidics, heat propagation, quantum billiards, and acoustics, the developed method can find numerous appl...
Structures of Spherical Viral Capsids as Quasicrystalline Tilings
O. V. Konevtsova; V. L. Lorman; S. B. Rochal
2015-01-16T23:59:59.000Z
Spherical viral shells with icosahedral symmetry are considered as quasicrystalline tilings. Similarly to known Caspar-Klug quasi-equivalence theory, the presented approach also minimizes the number of conformations necessary for the protein molecule bonding with its neighbors in the shell, but is based on different geometrical principles. It is assumed that protein molecule centers are located at vertices of tiles with identical edges, and the number of different tile types is minimal. Idealized coordinates of nonequivalent by symmetry protein positions in six various capsid types are obtained. The approach describes in a uniform way both the structures satisfying the well-known Caspar and Klug geometrical model and the structures contradicting this model.
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)
2009-04-02T23:59:59.000Z
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.
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.
1983-01-01T23:59:59.000Z
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.
On spherically-symmetric accretion by a collisionless polytrope
B. M. Lewis
2001-04-02T23:59:59.000Z
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 Cesium-Loaded Spherical Resorcinol Formaldehyde Resin: Data Summary Report
Kim, Dong-Sang; Schweiger, Michael J.; Peterson, Reid A.
2012-09-01T23:59:59.000Z
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.
Fire Safety Tests for Spherical Resorcinol Formaldehyde Resin: Data Summary Report
Kim, Dong-Sang; Peterson, Reid A.; Schweiger, Michael J.
2012-07-30T23:59:59.000Z
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.
An exact solution for the Casimir force in a spherically symmetric medium
Ulf Leonhardt; William M. R. Simpson
2011-07-03T23:59:59.000Z
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.
A Multipole Based Treecode Using Spherical Harmonics for Potentials of the Form r-
Sarin, Vivek
A Multipole Based Treecode Using Spherical Harmonics for Potentials of the Form r- Kasthuri spherical harmonics to compute multipole coefficients that are used to evaluate these potentials. The key of the multipole expansion theorem used in the classical fast multipole algorithm [2]. This theorem is used
Study of plasma heating in ohmically and auxiliary heated regimes in spherical tokamak Globus-M.
Boyer, Edmond
Study of plasma heating in ohmically and auxiliary heated regimes in spherical tokamak Globus-M. N, Russia INTRODUCTION This paper describes the basic features of the plasma heating in spherical tokamak direction in the tokamak midplane. The beam axis was aimed into the inner plasma region at the radius R = 0
McEwen, Jason
spherical wavelet transform algorithms J. D. McEwen, M. P. Hobson, D. J. Mortlock, A. N. Lasenby Abstract-- We describe the construction of a spherical wavelet analysis through the inverse stereographic projection of the Euclidean planar wavelet framework, introduced originally by Antoine and Vandergheynst
Identification of the hardening law of materials with spherical indentation using the average
the load-displacement curve of a spherical indentation test is proposed. This method is based on the use tensile test [19] . Identification of plastic hardening parameters from a load-penetration depth spherical indentation curve (F-h curve) is mostly used and the methods based on the representative strain
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
Processes for making dense, spherical active materials for lithium-ion cells
Kang, Sun-Ho (Naperville, IL); Amine, Khalil (Downers Grove, IL)
2011-11-22T23:59:59.000Z
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.
Zhang Yang [Institute of Applied Physics and Computational Mathematics, P. O. Box 8009-09, Beijing 100094 (China); Institute of Nuclear Physics and Chemistry, P. O. Box 919-212, Mianyang 621900 (China); Ding Ning; Sun Shunkai; Xue Chuang; Ning Cheng; Xiao Delong; Huang Jun [Institute of Applied Physics and Computational Mathematics, P. O. Box 8009-09, Beijing 100094 (China); Li Zhenghong [Institute of Nuclear Physics and Chemistry, P. O. Box 919-212, Mianyang 621900 (China)
2012-12-15T23:59:59.000Z
Implosions of (quasi-)spherical loads with mass redistribution and displacement modification are investigated numerically. Both methods can theoretically counterbalance the nonuniformity of magnetic pressure along the load surface and realize quasi-spherical Z-pinch implosions. Mass redistribution is feasible for spherical loads with large radius and weight, while the displacement modification is more suitable for light loads, such as those composed of wire arrays. Simulation results suggest that, for mass redistributed spherical loads, wall instabilities induced by polar mass flows will deform the imploding shell. For prolate spherical loads, in which the wall instability cannot develop, the kinetic energy distribution is disturbed at high latitude. These passive behaviors and their possible mitigation methods, such as reshaping the electrode, are investigated numerically in this paper.
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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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItemResearch > The EnergyCenterDioxide CaptureSeeNUCLEAR SCIENCE WEEKSecurity LLNL's
Office of Scientific and Technical Information (OSTI)
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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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742 33Frequently Asked QuestionsDepartment of Energy 3Services and LowersSafety andNASAand North
An "adiabatic-hindered-rotor" treatment allows para-H2 to be treated as if it were spherical
Le Roy, Robert J.
An "adiabatic-hindered-rotor" treatment allows para-H2 to be treated as if it were spherical Hui LiÂ molecule interactions, the common assumption that para-H2 may be treated as a spherical particle is often K , it is often considered a good approximation to treat para-H2 as a spherical particle.1
Fractal boundary basins in spherically symmetric $?^4$ theory
Ethan P. Honda
2011-06-14T23:59:59.000Z
Results are presented from numerical simulations of the flat-space nonlinear Klein-Gordon equa- tion with an asymmetric double-well potential in spherical symmetry. Exit criteria are defined for the simulations that are used to help understand the boundaries of the basins of attraction for Gaussian "bubble" initial data. The first exit criteria, based on the immediate collapse or expan- sion of bubble radius, is used to observe the departure of the scalar field from a static intermediate attractor solution. The boundary separating these two behaviors in parameter space is smooth and demonstrates a time-scaling law with an exponent that depends on the asymmetry of the potential. The second exit criteria differentiates between the creation of an expanding true-vacuum bubble and dispersion of the field leaving the false vacuum; the boundary separating these basins of attraction is shown to demonstrate fractal behavior. The basins are defined by the number of bounces that the field undergoes before inducing a phase transition. A third, hybrid exit criteria is used to determine the location of the boundary to arbitrary precision and to characterize the threshold behavior. The possible effects this behavior might have on cosmological phase transitions are briefly discussed.
THE SPHERICALIZATION OF DARK MATTER HALOS BY GALAXY DISKS
Kazantzidis, Stelios [Center for Cosmology and Astro-Particle Physics, Ohio State University, Columbus, OH 43210 (United States); Abadi, Mario G. [Instituto de Astronomia Teorica y Experimental (IATE), Observatorio Astronomico de Cordoba and CONICET, Laprida 854 X5000BGR Cordoba (Argentina); Navarro, Julio F., E-mail: stelios@mps.ohio-state.ed, E-mail: mario@oac.uncor.ed, E-mail: jfn@uvic.c [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2 (Canada)
2010-09-01T23:59:59.000Z
Cosmological simulations indicate that cold dark matter (CDM) halos should be triaxial. Validating this theoretical prediction is, however, less than straightforward because the assembly of galaxies is expected to modify halo shapes and to render them more axisymmetric. We use a suite of N-body simulations to quantitatively investigate the effect of the growth of a central disk galaxy on the shape of triaxial dark matter halos. In most circumstances, the halo responds to the presence of the disk by becoming more spherical. The net effect depends weakly on the timescale of the disk assembly but noticeably on the orientation of the disk relative to the halo principal axes, and it is maximal when the disk symmetry axis is aligned with the major axis of the halo. The effect depends most sensitively on the overall gravitational importance of the disk. Our results indicate that exponential disks whose contribution peaks at less than {approx}50% of their circular velocity are unable to noticeably modify the shape of the gravitational potential of their surrounding halos. Many dwarf and low surface brightness galaxies are expected to be in this regime, and therefore their detailed kinematics could be used to probe halo triaxiality, one of the basic predictions of the CDM paradigm. We argue that the complex disk kinematics of the dwarf galaxy NGC 2976 might be the reflection of a triaxial halo. Such signatures of halo triaxiality should be common in galaxies where the luminous component is subdominant.
Self Assembled Clusters of Spheres Related to Spherical Codes
Carolyn L. Phillips; Eric Jankowski; Michelle Marval; Sharon C. Glotzer
2012-01-24T23:59:59.000Z
We consider the thermodynamically driven self-assembly of spheres onto the surface of a central sphere. This assembly process forms self-limiting, or terminal, anisotropic clusters (N-clusters) with well defined structures. We use Brownian dynamics to model the assembly of N-clusters varying in size from two to twelve outer spheres, and free energy calculations to predict the expected cluster sizes and shapes as a function of temperature and inner particle diameter. We show that the arrangements of outer spheres at finite temperatures are related to spherical codes, an ideal mathematical sequence of points corresponding to densest possible sphere packings. We demonstrate that temperature and the ratio of the diameters of the inner and outer spheres dictate cluster morphology and dynamics. We find that some N-clusters exhibit collective particle rearrangements, and these collective modes are unique to a given cluster size N. We present a surprising result for the equilibrium structure of a 5-cluster, which prefers an asymmetric square pyramid arrangement over a more symmetric arrangement. Our results suggest a promising way to assemble anisotropic building blocks from constituent colloidal spheres.
A Keplerian Limit to Static Spherical Spacetimes in Curvature Coordinates
Tyler J. Lemmon; Antonio R. Mondragon
2008-09-04T23:59:59.000Z
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.
Local Casimir Energies for a Thin Spherical Shell
Ines Cavero-Pelaez; Kimball A. Milton; Jeffrey Wagner
2006-02-01T23:59:59.000Z
The local Casimir energy density for a massless scalar field associated with step-function potentials in a 3+1 dimensional spherical geometry is considered. The potential is chosen to be zero except in a shell of thickness $\\delta$, where it has height $h$, with the constraint $h\\delta=1$. In the limit of zero thickness, an ideal $\\delta$-function shell is recovered. The behavior of the energy density as the surface of the shell is approached is studied in both the strong and weak coupling regimes. The former case corresponds to the well-known Dirichlet shell limit. New results, which shed light on the nature of surface divergences and on the energy contained within the shell, are obtained in the weak coupling limit, and for a shell of finite thickness. In the case of zero thickness, the energy has a contribution not only from the local energy density, but from an energy term residing entirely on the surface. It is shown that the latter coincides with the integrated local energy density within the shell. We also study the dependence of local and global quantities on the conformal parameter. In particular new insight is provided on the reason for the divergence in the global Casimir energy in third order in the coupling.
Relaxation in N-body simulations of spherical systems
Sellwood, J A
2015-01-01T23:59:59.000Z
I present empirical measurements of the rate of relaxation in N-body simulations of stable spherical systems and distinguish two separate causes of relaxation: two-body effects, which cause energy exchange between particles of differing masses, and collective oscillations driven by shot noise that lead to an enhanced energy diffusion rate. I use four different methods to compute the gravitational field, and a 100-fold range in the numbers of particles in each case. I find the rate at which energy is exchanged between particles of differing masses does not depend at all on the force determination method, but I do find the energy diffusion rate, which is substantially enhanced by collective modes, is marginally lower when a field method is used. The relaxation rate in 3D is virtually independent of the method used because it is dominated by distant encounters; any method to estimate the gravitational field that correctly captures the contributions from distant particles must also capture their statistical fluct...
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)
2014-05-15T23:59:59.000Z
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.
Analysis of spherically symmetric black holes in Braneworld models
A. B. Pavan
2010-05-25T23:59:59.000Z
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.
Spherical Collapse Model And Dark Energy(I)
Ding-fang Zeng; Yi-hong Gao
2005-05-09T23:59:59.000Z
In existing literatures about the top-hat spherical collapse model of galaxy clusters formation in cosmology containing dark energies, dark energies are usually assumed not to cluster on this scale. But all these literatures ignored the current describing the flowing of dark energies outside the clusters which should exist under this assumption, so the conclusions of these literatures are worth further explorations. In this paper we study this model in QCDM or Phantom-CDM cosmologies(flat) by assuming that dark energies will cluster synchronously with ordinary matters on the scale of galaxy clusters so the dark energy current flowing outside the clusters does not exist at all and find that in this case, the key parameters of the model exhibit rather non-trivial and remarkable dependence on the equation of state coefficients of dark energies. We then apply the results in Press-Scheter theory and calculate the number density of galaxy clusters and its evolutions. We find that this two quantities are both affected exponentially by the equation of state coefficients of dark energies. We leave the study of this model with the assumption that dark energies do not cluster on the scale of galaxy clusters at all as the topic of another paper where similar conclusions will be obtained also.
MFE Concept Integration and Performance Measures Magnetic Fusion Concept Working Group
, spherical torus, compact stellarator, reversed-field pinch, and spheromak The goal was to identify, for each
National System Templates: Building Sustainable National Inventory...
Templates: Building Sustainable National Inventory Management Systems Jump to: navigation, search Tool Summary LAUNCH TOOL Name: National System Templates: Building Sustainable...
New framework for studying spherically symmetric static solutions in f(R) gravity
Nzioki, Anne Marie; Goswami, Rituparno [Astrophysics, Cosmology and Gravity Centre (ACGC), University of Cape Town, Rondebosch, 7701 (South Africa); Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch, 7701 (South Africa); Carloni, Sante [Institut d'Estudis Espacials de Catalunya (IEEC), Campus UAB, Facultat Ciencies, Torre C5-Par-2a pl, E-08193 Bellaterra (Barcelona) (Spain); Dunsby, Peter K. S. [Astrophysics, Cosmology and Gravity Centre (ACGC), University of Cape Town, Rondebosch, 7701 (South Africa); Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch, 7701 (South Africa); South African Astronomical Observatory, Observatory, Cape Town (South Africa)
2010-04-15T23:59:59.000Z
We develop a new covariant formalism to treat spherically symmetric spacetimes in metric f(R) theories of gravity. Using this formalism we derive the general equations for a static and spherically symmetric metric in a general f(R) gravity. These equations are used to determine the conditions for which the Schwarzschild metric is the only vacuum solution with vanishing Ricci scalar. We also show that our general framework provides a clear way of showing that the Schwarzschild solution is not a unique static spherically symmetric solution, providing some insight into how the current form of Birkhoff's theorem breaks down for these theories.
Energy-momentum Prescriptions in General Spherically Symmetric Space-times
Saeed Mirshekari; Amir M. Abbassi
2014-11-29T23:59:59.000Z
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.
Facilities | Argonne National Laboratory
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Some of the nation's most powerful and sophisticated facilities for energy research Argonne National Laboratory is home to some of the nation's most powerful and sophisticated...
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
2009-10-29T23:59:59.000Z
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.
. Sabbagh Â Columbia University 12/14/11 v1 Dear Dale and the FESAC International Collaboration Panel Professor of Applied Physics Columbia University National Spherical Torus Experiment Run Coordinator. Sabbagh Â Columbia University 12/14/11 v1 Suggestions are arranged in the following manner: (A) Research
NSTX Weekly Report (May 21, 2010) FY 2010 NSTX plasma operations
Princeton Plasma Physics Laboratory
Diagnostics for Liquid Lithium Divertor Studies on the National Spherical Torus Experiment" by V University), "Modeling the Polarization Properties of Propagating Electromagnetic Waves in NSTX" by J. Zhang Plasma Physics and Plasma Material Interactions in the Fusion Power Plant Regime" 20-21 May 2010 at UC
PREPARED FOR THE U.S. DEPARTMENT OF ENERGY, UNDER CONTRACT DE-AC02-76CH03073
Ion Loss in the National Spherical Torus Experiment by E.D. Fredrickson, C.Z. Cheng, D. Darrow, G. Fu Experiment E.D. Fredrickson, C.Z. Cheng, D. Darrow, G. Fu, N.N. Gorelenkov, G Kramer, S S Medley, J. Menard
PREPARED FOR THE U.S. DEPARTMENT OF ENERGY, UNDER CONTRACT DE-AC02-76CH03073
.D. Fredrickson, N. Gorelenkov, C.Z. Cheng, R. Bell, D. Darrow, D. Johnson, S. Kaye, B. LeBlanc, J. Menard, S on the National Spherical Torus Experiment E.D. Fredrickson, N. Gorelenkov, C.Z. Cheng, R. Bell, D. Darrow, D
PREPARED FOR THE U.S. DEPARTMENT OF ENERGY, UNDER CONTRACT DE-AC02-76CH03073
.D. Fredrickson, N. Gorelenkov, C.Z. Cheng, R. Bell, D. Darrow, D. Johnson, S. Kaye, B. LeBlanc, J. Menard, S Beam Heating on the National Spherical Torus Experiment E.D. Fredrickson, N. Gorelenkov, C.Z. Cheng, R
DIMENSIONS of DISCOVERY Sponsored Program Awards
Ginzel, Matthew
of a Stent Prototype to Induce Closure of Post-Traumatic Blast-Induced Pseudo-Aneurysms; Modification 1) and its Effect on High Performance Plasmas in National Spherical Torus Experiment (NSTX)." Allebach, Jan P." Applegate, Todd J; animal sciences, from Purac, $43,632, "Effect of Form and Dos- age of Lactylate
PREPARED FOR THE U.S. DEPARTMENT OF ENERGY, UNDER CONTRACT DE-AC02-76CH03073
in Calendar Year 2001. The home page for PPPL Reports and Publications is: http://www.pppl.gov/pub_report/ DOE, Princeton, New Jersey 08543, USA Abstract Neutral beam (NB) heating in the National Spherical Torus auxiliary heating. NB heating experiments in NSTX began in September 2000 using up to 5 MW of 80 keV D beams
Den Hartog, D. J.; Craig, D.; Ennis, D. A.; Fiksel, G.; Gangadhara, S.; Holly, D. J.; Reardon, J. C.; Davydenko, V. I.; Ivanov, A. A.; Lizunov, A. A.; O'Mullane, M. G.; Summers, H. P. [Department of Physics, and Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation); University of Strathclyde, Glasgow, G1 1XQ Scotland (United Kingdom)
2006-10-15T23:59:59.000Z
Innovative charge-exchange recombination spectroscopy (CHERS), motional Stark effect (MSE), and Rutherford scattering diagnostics are now in operation on the Madison Symmetric Torus (MST) reversed-field pinch (RFP). The CHERS diagnostic measures impurity ion flow and temperature, localized to 2 cm with high time resolution ({approx}100 kHz). A spectral MSE diagnostic has been in use for five years, measuring |B| down to 0.2 T with high precision ({approx}2%) and good time resolution (10 kHz). The Rutherford scattering diagnostic has demonstrated the robustness of this technique for reliable measurement of majority (D) ion temperature, also with high time resolution. MST is a large RFP (R=1.5 m, a=0.52 m) operated at moderate current (I{sub p}{<=}600 kA), with n{sub e} typically (1-2)x10{sup 19} m{sup -3} and T{sub e}, T{sub i}{<=}2 keV. Two compact and reliable diagnostic neutral beams are installed on MST. These beams are short pulse, intense, monoenergetic, and low divergence. The first, a neutral H beam, is used in combination with ultraviolet and visible spectroscopy to make the CHERS and MSE measurements. For CHERS, the C VI line at 343.4 nm is collected by a custom high-throughput double grating spectrometer which simultaneously records both charge-exchange and background emissions. The spectrum is analyzed using a sophisticated model derived from the Atomic Database and Analysis Structure (ADAS) package. The MSE system records the entire H{alpha} Stark spectrum; |B| is derived from the measured splitting of the {pi}{sup +} and {pi}{sup -} manifolds. Measurement of |B| is critical to accurate equilibrium reconstruction in the RFP. The second diagnostic beam is a 20 keV neutral He beam and is used for the Rutherford scattering measurements. A pair of neutral particle analyzers is used to record the energy spectrum of the small-angle Rutherford scattered He atoms.
A classification of spherically symmetric self-similar dust models
B. J. Carr
2000-03-02T23:59:59.000Z
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.
Arbanas, G; Elster, C; Escher, J; Mukhamedzanov, A; Nunes, F; Thompson, I J
2012-02-24T23:59:59.000Z
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 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.
A two-phase spherical electric machine for generating rotating uniform magnetic fields
Lawler, Clinton T. (Clinton Thomas)
2007-01-01T23:59:59.000Z
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 ...
Kapila Bala, Phani Neehar
2012-10-19T23:59:59.000Z
of the failure recovery technique were obtained for the case of Elbow failure in robot manipulators. The thesis considers two applications of the synthesis of spherical five –degree-of-freedom serial chains: Power assist for human therapeutic movement...
Conformally flat Einstein-Yang-Mills-Higgs solutions with spherical symmetry
Mondaini, R.P.; Santos, N.O.
1983-10-15T23:59:59.000Z
We solve the Einstein-Yang-Mills-Higgs equations in a conformally flat metric with spherical symmetry. Two solutions are obtained corresponding to magnetic monopoles in the Higgs vacuum and outside of it.
Laverty, Stephen Michael
2005-01-01T23:59:59.000Z
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 ...
Radio emission from weak spherical shocks in the outskirts of galaxy clusters
Kang, Hyesung
2015-01-01T23:59:59.000Z
In Kang (2015) we calculated the acceleration of cosmic-ray electrons and the ensuing radio synchrotron emission at weak spherical shocks that are expected to form in the outskirts of galaxy clusters.There we demonstrated that, at decelerating spherical shocks, the volume integrated spectra of both electrons and radiation deviate significantly from the test-particle power-laws predicted for constant planar shocks, because the shock compression ratio and the flux of injected electrons decrease in time. In this study, we consider spherical blast waves propagating into a constant density core surrounded by an isothermal halo with a decreasing density profile in order to explore how the deceleration rate of the shock speed affects the radio emission from accelerated electrons. The surface brightness profile and the volume-integrated radio spectrum of the model shocks are calculated by assuming a ribbon-like shock surface on a spherical shell and the associated downstream region of relativistic electrons. If the p...
Spherically symmetric brane spacetime with bulk $f(\\mathcal{R})$ gravity
Sumanta Chakraborty; Soumitra SenGupta
2015-01-15T23:59:59.000Z
Introducing $f(\\mathcal{R})$ term in the five-dimensional bulk action we derive effective Einstein's equation on the brane using Gauss-Codazzi equation. This effective equation is then solved for different conditions on dark radiation and dark pressure to obtain various spherically symmetric solutions. Some of these static spherically symmetric solutions correspond to black hole solutions, with parameters induced from the bulk. Specially, the dark pressure and dark radiation terms (electric part of Weyl curvature) affect the brane spherically symmetric solutions significantly. We have solved for one parameter group of conformal motions where the dark radiation and dark pressure terms are exactly obtained exploiting the corresponding Lie symmetry. Various thermodynamic features of these spherically symmetric space-times are studied, showing existence of second order phase transition. This phenomenon has its origin in the higher curvature term with $f(\\mathcal{R})$ gravity in the bulk.
Design of a spherical vehicle with flywheel momentum storage for high torque capabilities
Schroll, Gregory C. (Gregory Cordner)
2008-01-01T23:59:59.000Z
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 ...
Gravitational radiation, energy and reaction on quasi-spherical black holes
Sean A. Hayward
2001-02-05T23:59:59.000Z
Gravitational radiation is locally defined where the wavefronts are roughly spherical. A local energy tensor is defined for the gravitational radiation. Including this energy tensor as a source in the truncated Einstein equations describes gravitational radiation reaction, such as back-reaction on a roughly spherical black hole. The energy-momentum in a canonical frame is covariantly conserved. The strain to be measured by a distant detector is simply defined.
Kliem, B
2006-01-01T23:59:59.000Z
The expansion instability of a toroidal current ring in low-beta magnetized plasma is investigated. Qualitative agreement is obtained with experiments on spheromak expansion and with essential properties of solar coronal mass ejections (CMEs), unifying the two apparently disparate classes of fast and slow CMEs.
Investigation of Gas Solid Fluidized Bed Dynamics with Non-Spherical Particles
Choudhuri, Ahsan
2013-06-30T23:59:59.000Z
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.
Hydrodynamic and numerical modeling of a spherical homogeneous.pdf
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Hysteresis cycle in a turbulent, spherically bounded MHD dynamo model
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Brookhaven National Laboratory National Synchrotron Light Source
Ohta, Shigemi
Brookhaven National Laboratory National Synchrotron Light Source Number: Revision: LS-ESH-0027 06 copy of this file is the one on-line in the NSLS ESH website. Before using a printed copy, verify that it is the most current version by checking the document issue date on the NSLS ESH website. BROOKHAVEN NATIONAL
Brookhaven National Laboratory National Synchrotron Light Source
Ohta, Shigemi
Brookhaven National Laboratory National Synchrotron Light Source Number: Revision: PS-ESH-0025 01 of this file is the one on-line in the NSLS ESH website. Before using a printed copy, verify that it is the most current version by checking the document issue date on the NSLS ESH website. BROOKHAVEN NATIONAL
Brookhaven National Laboratory National Synchrotron Light Source
Ohta, Shigemi
Brookhaven National Laboratory National Synchrotron Light Source Number: Revision: LS-ESH-0026 4 of this file is the one on-line in the PS ESH website. Before using a printed copy, verify that it is the most current version by checking the document issue date on the PS ESH website. BROOKHAVEN NATIONAL LABORATORY
Kuritsyn, A.; Fiksel, G.; Miller, M. C.; Almagri, A. F.; Reyfman, M.; Sarff, J. S. [Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas and Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
2008-10-15T23:59:59.000Z
Several probes have been constructed to measure fluctuation-induced Maxwell and Reynolds stresses in the edge of the Madison Symmetric Torus reversed field pinch (RFP). The magnetic probe is composed of six magnetic pickup coil triplets. The triplets are separated spatially, which allows for local measurements of the Maxwell stress. To measure the plasma flow components for evaluation of the Reynolds stress, we employ a combination of an optical probe [Kuritsyn et al., Rev. Sci. Indrum. 77, 10F112 (2006)] and a Mach probe. The optical probe measures the radial ion flow locally using Doppler spectroscopy. The Mach probe consists of four current collectors biased negatively with respect to a reference tip and allows for measurements of the poloidal and toroidal components of the bulk plasma flow. The stresses are observed to play an important role in the momentum balance in the RFP edge during internal reconnection events.
Angelone, M. (JET Joint Undertaking Abingdon, Oxon (United Kingdom))
1993-08-01T23:59:59.000Z
The first attempt to calculate the parameters for [sup 238]U and [sup 232]Th used in the analysis of delayed neutron counter measurements of the total neutron yield from deuterium-tritium (D-T) plasmas is described. The nuclear theory of systematics is employed, together with nuclear data from the literature. As a check on the methods used, the delayed neutron parameters were also calculated for deuterium-deuterium plasma conditions; the resulting neutron yields agreed within [+-]7% with the results obtained using the experimentally calibrated delayed neutron counter assemblies. After the calculations were completed, the first D-T plasma experiment was performed at the Joint European Torus (JET). Delayed neutron measurements were made using [sup 232]Th samples. The calculated delayed neutron parameters gave neutron yields that agreed within [+-]8% with those obtained with conventional activation methods, using iron and silicon samples. 30 refs., 5 figs., 8 tabs.
Hossack, Aaron C.; Jarboe, Thomas R.; Victor, Brian S. [Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195 (United States)] [Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195 (United States); Firman, Taylor; Prager, James R.; Ziemba, Timothy [Eagle Harbor Technologies, Inc., 119 W. Denny Way, Suite 210, Seattle, Washington 98119 (United States)] [Eagle Harbor Technologies, Inc., 119 W. Denny Way, Suite 210, Seattle, Washington 98119 (United States); Wrobel, Jonathan S. [979B West Moorhead Circle, Boulder, Colorado 80305 (United States)] [979B West Moorhead Circle, Boulder, Colorado 80305 (United States)
2013-10-15T23:59:59.000Z
A helicon based pre-ionization source has been developed and installed on the Helicity Injected Torus with Steady Inductance (HIT-SI) spheromak. The source initiates plasma breakdown by injecting impurity-free, unmagnetized plasma into the HIT-SI confinement volume. Typical helium spheromaks have electron density reduced from (2–3) × 10{sup 19} m{sup ?3} to 1 × 10{sup 19} m{sup ?3}. Deuterium spheromak formation is possible with density as low as 2 × 10{sup 18} m{sup ?3}. The source also enables HIT-SI to be operated with only one helicity injector at injector frequencies above 14.5 kHz. A theory explaining the physical mechanism driving the reduction of breakdown density is presented.
The construction of non-spherical models of quasi-relaxed stellar systems
G. Bertin; A. L. Varri
2008-08-18T23:59:59.000Z
Spherical models of collisionless but quasi-relaxed stellar systems have long been studied as a natural framework for the description of globular clusters. Here we consider the construction of self-consistent models under the same physical conditions, but including explicitly the ingredients that lead to departures from spherical symmetry. In particular, we focus on the effects of the tidal field associated with the hosting galaxy. We then take a stellar system on a circular orbit inside a galaxy represented as a "frozen" external field. The equilibrium distribution function is obtained from the one describing the spherical case by replacing the energy integral with the relevant Jacobi integral in the presence of the external tidal field. Then the construction of the model requires the investigation of a singular perturbation problem for an elliptic partial differential equation with a free boundary, for which we provide a method of solution to any desired order, with explicit solutions to two orders. We outline the relevant parameter space, thus opening the way to a systematic study of the properties of a two-parameter family of physically justified non-spherical models of quasi-relaxed stellar systems. The general method developed here can also be used to construct models for which the non-spherical shape is due to internal rotation. Eventually, the models will be a useful tool to investigate whether the shapes of globular clusters are primarily determined by internal rotation, by external tides, or by pressure anisotropy.
Non-astigmatic imaging with matched pairs of spherically bent reflectors
Bitter, Manfred Ludwig (Princeton, NJ); Hill, Kenneth Wayne (Plainsboro, NJ); Scott, Steven Douglas (Wellesley, MA); Feder, Russell (Newton, PA); Ko, Jinseok (Cambridge, MA); Rice, John E. (N. Billerica, MA); Ince-Cushman, Alexander Charles (New York, NY); Jones, Frank (Manalapan, NJ)
2012-07-10T23:59:59.000Z
Arrangements for the point-to-point imaging of a broad spectrum of electromagnetic radiation and ultrasound at large angles of incidence employ matched pairs of spherically bent reflectors to eliminate astigmatic imaging errors. Matched pairs of spherically bent crystals or spherically bent multi-layers are used for X-rays and EUV radiation; and matched pairs of spherically bent mirrors that are appropriate for the type of radiation are used with microwaves, infrared and visible light, or ultrasound. The arrangements encompass the two cases, where the Bragg angle--the complement to the angle of incidence in optics--is between 45.degree. and 90.degree. on both crystals/mirrors or between 0.degree. and 45.degree. on the first crystal/mirror and between 45.degree. and 90.degree. on the second crystal/mirror, where the angles of convergence and divergence are equal. For x-rays and EUV radiation, also the Bragg condition is satisfied on both spherically bent crystals/multi-layers.
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...
None
2010-09-01T23:59:59.000Z
National Science Bowl finals and awards at the National Building Museum in Washington D.C. Monday 5/3/2010
Sandia National Laboratories: solar
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Interactive Tour Operated by Sandia National Laboratories for the U.S. Department of Energy (DOE), the National Solar Thermal Test Facility (NSTTF) is the only test facility...
Sandia National Laboratories: PV
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2014 Sandia Corporation | Questions & Comments | Privacy & Security U.S. Department of Energy National Nuclear Security Administration Sandia National Laboratories is a...
Sandia National Laboratories: Energy
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National Solar Thermal Test Facility, News, News & Events, Partnership, Renewable Energy, Solar, Solar Newsletter On November 24, 2012 the National Solar Thermal Test...
Sandia National Laboratories: ACEC
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ACEC Sandia Solar Energy Test System Cited in National Engineering Competition On May 16, 2013, in Concentrating Solar Power, Energy, Energy Storage, Facilities, National Solar...
2010-05-03T23:59:59.000Z
National Science Bowl finals and awards at the National Building Museum in Washington D.C. Monday 5/3/2010
National Nuclear Security Administration
Broader source: Energy.gov (indexed) [DOE]
and Related Structures within TA-3 at Los Alamos National Laboratory, Los Alamos, New Mexico U. S. Department of Energy National Nuclear Security Administration Los Alamos Area...
Self-Gravitating Spherically Symmetric Solutions in Scalar-Torsion Theories
Kofinas, Georgios; Saridakis, Emmanuel N
2015-01-01T23:59:59.000Z
We studied spherically symmetric solutions in scalar-torsion gravity theories in which a scalar field is coupled to torsion with a derivative coupling. We obtained the general field equations from which we extracted a decoupled master equation, the solution of which leads to the specification of all other unknown functions. We first obtained an exact solution which represents a new wormhole-like solution dressed with a regular scalar field. Then, we found large distance linearized spherically symmetric solutions in which the space asymptotically is AdS.
Photoplastic analysis of polycarbonate loaded by spherical indentator using strain-freezing method
Shimamoto, Akira [Saitama Institute of Technology (Japan); Umezaki, Eisaku [Nippon Institute of Technology, Saitama (Japan); Nogata, Fumio [Himeji Institute of Technology, Hyogo (Japan); Takahashi, Susumu [Kanto Gakuin Univ., Yokohama (Japan)
1996-12-31T23:59:59.000Z
Hardness test is one of the basic material testings. This investigates strain behavior in polycarbonate loaded by a spherical indentator using the strain-freezing method to establish a method of evaluating the material properties of polymers which have been widely used as machine parts and structural members because of a high elastic modulus and strength. As a result, the strain-freezing method was found to be effective for analyzing strains in polycarbonate loaded by a spherical indentator. Furthermore, the relation between the photoelastic fringe order and principal strain difference is found to be proportional as well as the relation between the total strain.
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
Sandia National Laboratories: Sandia National Laboratories
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in Hosted by Sandia National Laboratories and the Electric Power Research Institute (EPRI) Inverter reliability drives project life cycle costs and plant performance. This...
Sandia National Laboratories: National Rotor Testbed Functional...
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of the National Rotor Testbed: An Aeroelastically Relevant Research-Scale Wind Turbine Rotor." Approximately 60 researchers from various institutions and countries attended...
Consent Order, Lawrence Livermore National National Security...
for deficiencies associated with the Lawrence Livermore National Laboratory Chronic Beryllium Disease Prevention Program On October 29, 2010, the U.S. Department of Energy (DOE)...
Sandia National Laboratories: Jawaharlal Nehru Solar National...
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Jawaharlal Nehru Solar National Solar Energy Mission Solar Energy Research Institute for India and the United States Kick-Off On November 27, 2012, in Concentrating Solar Power,...
National Security Photo Gallery | Argonne National Laboratory
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National Security Photo Gallery Richard Cirillo 1 of 10 Richard Cirillo RICHARD R. CIRILLO Dr. Richard R. Cirillo serves as Director of the Decision and Information Sciences...
Sandia National Laboratories: national reliability database
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national reliability database Third Annual Continuous Reliability Enhancement for Wind (CREW) Database Report Now Available On October 17, 2013, in Energy, News, News & Events,...
Argonne National Laboratory | Argonne National Laboratory
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Argonne National Laboratory Slip sliding away Graphene and diamonds prove a slippery combination Read More ACT-SO winners Argonne mentors students for the next generation of...
Sengun, Mehmet Haluk
Spherical Tokamak J. R. Robinson1, B. Hnat1, P. Dura1, A. Kirk2, P. Tamain3, A. Thyagaraja4, K. G. Mc Acoustic Mode (GAM) at the edge of an Ohmic plasma on the Mega Amp Spherical Tokamak (MAST). A strong 10 k
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
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
Boss, Emmanuel S.
-Pi measured roughly 0.5m diameter x 1 m long and did not incorporate batteries or computer; contrasted with LISST at 0.12 m dia x 0.7 m long, roughly 20 times smaller, yet complete with battery and data logger-spherical effects on backscatter. b. Characterization of scattering from terrigenous and biological size-sorted non
Comment on "Static and spherically symmetric black holes in f(R) theories"
S. Habib Mazharimousavi; M. Halilsoy
2012-10-17T23:59:59.000Z
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
Walter, M.Todd
.48/7.28/22.83, respectively, were previously shown to replicate certain gas phase combustion properties of JetSpherically symmetric droplet combustion of three and four component miscible mixtures This study examines the droplet combustion characteristics of three and four component miscible liquid
Walter, M.Todd
.53Â0.57 mm and the combustion gas is normal atmospheric pressure air. A detailed numerical simulationOn the spherically symmetrical combustion of methyl decanoate droplets and comparisons Biodiesel Biofuel Microgravity Numerical Droplet combustion a b s t r a c t This study presents
Calibration of broadband active acoustic systems using a single standard spherical target
Stanton, Tim
Calibration of broadband active acoustic systems using a single standard spherical target Timothy K 8 April 2008 When calibrating a broadband active acoustic system with a single standard target the concept of using this echo for calibration in the work of Dragonette et al. J. Acoust. Soc. Am. 69, 1186
Farhad Ali
2014-12-30T23:59:59.000Z
In this paper we present Plane symmetric, Cylindrically Symmetric and Spherically Symmetric Black hole or Vacuum solutions of Einstein Field Equations(EFEs). Some of these solutions are new which we have not seen in the literature. This calculation will help us in understanding the gravitational wave and gravitational wave spacetimes.
Local Casimir Energies for a Thin Spherical Shell Ines Cavero-Pelaez,
Milton, Kim
Local Casimir Energies for a Thin Spherical Shell InÂ´es Cavero-PelÂ´aez, Kimball A. Milton. In the limit of zero thickness, an ideal -function shell is recovered. The behavior of the energy density of surface divergences and on the energy contained within the shell, are obtained in the weak coupling limit
Phenomenological study of parabolic and spherical indentation of elastic-ideally plastic material
Paris-Sud XI, Université de
Phenomenological study of parabolic and spherical indentation of elastic-ideally plastic material O ideally plastic materials was carried out by using precise results of finite elements calculations behaviour is found. Two elastic-plastic regimes and two plastic regimes are observed for materials of very
Braatz, Richard D.
, but are immiscible with each other as the solvent volume decreases.4Â9 Water-in-oil emulsions, where the water, evaporation, population balance, pervaporation, mathematical modeling, transport Introduction The emulsionPervaporation of Emulsion Droplets for the Templated Assembly of Spherical Particles: A Population
Sánchez, Juan
by differentially-heated solid spherical shells is mainly considered. Asymptotic power laws for the mean physical and compositional buoy- ancy forces (Lister and Buffet (1995); Poirier (2000)) in this paper we focus on the imprint- tial bodies. Good reviews can be found in the literature, see for instance Cardin and Olson (1994
Extended Soft Binding Mean Spherical- Contact Probability Approximation for Hard Ions
Blum, L. [Department of Mathematics, Rutgers University (United States); Arias, M.; Veloz, D. V. Perez [Physics Department, University of Puerto Rico (Puerto Rico)
2009-03-09T23:59:59.000Z
We propose a new analytical theory of electrolytes that extends the range of the Mean Spherical Approximation (MSA) to include extremely high charges [1, 2, 3, 4, 5]. In the MSA the thermodynamics and structure of the most general electrolyte are given in terms of a single screening parameter {gamma}, [1] which is obtained from the simple algebraic equation.
Levis, Aviad; Aides, Amit; Davis, Anthony B
2015-01-01T23:59:59.000Z
This paper introduces a method to preform optical tomography, using 3D radiative transfer as the forward model. We use an iterative approach predicated on the Spherical Harmonics Discrete Ordinates Method (SHDOM) to solve the optimization problem in a scalable manner. We illustrate with an application in remote sensing of a cloudy atmosphere.
Adiabatic Quasi-Spherical Compressions Driven by Magnetic Pressure for Inertial Confinement Fusion
NASH,THOMAS J.
2000-11-01T23:59:59.000Z
The magnetic implosion of a high-Z quasi-spherical shell filled with DT fuel by the 20-MA Z accelerator can heat the fuel to near-ignition temperature. The attainable implosion velocity on Z, 13-cm/{micro}s, is fast enough that thermal losses from the fuel to the shell are small. The high-Z shell traps radiation losses from the fuel, and the fuel reaches a high enough density to reabsorb the trapped radiation. The implosion is then nearly adiabatic. In this case the temperature of the fuel increases as the square of the convergence. The initial temperature of the fuel is set by the heating of an ion acoustic wave to be about 200-eV after a convergence of 4. To reach the ignition temperature of 5-keV an additional convergence of 5 is required. The implosion dynamics of the quasi-spherical implosion is modeled with the 2-D radiation hydrodynamic code LASNEX. LASNEX shows an 8-mm diameter quasi-spherical tungsten shell on Z driving 6-atmospheres of DT fuel nearly to ignition at 3.5-keV with a convergence of 20. The convergence is limited by mass flow along the surface of the quasi-spherical shell. With a convergence of 20 the final spot size is 400-{micro}m in diameter.
On the critical flame radius and minimum ignition energy for spherical flame initiation
Chen, Zheng; Burke, M. P.; Ju, Yiguang
2011-01-01T23:59:59.000Z
Spherical flame initiation from an ignition kernel is studied theoretically and numerically using different fuel/oxygen/helium/argon mixtures (fuel: hydrogen, methane, and propane). The emphasis is placed on investigating the critical flame radius controlling spherical flame initiation and its correlation with the minimum ignition energy. It is found that the critical flame radius is different from the flame thickness and the flame ball radius and that their relationship depends strongly on the Lewis number. Three different flame regimes in terms of the Lewis number are observed and a new criterion for the critical flame radius is introduced. For mixtures with Lewis number larger than a critical Lewis number above unity, the critical flame radius is smaller than the flame ball radius but larger than the flame thickness. As a result, the minimum ignition energy can be substantially over-predicted (under-predicted) based on the flame ball radius (the flame thickness). The results also show that the minimum ignition energy for successful spherical flame initiation is proportional to the cube of the critical flame radius. Furthermore, preferential diffusion of heat and mass (i.e. the Lewis number effect) is found to play an important role in both spherical flame initiation and flame kernel evolution after ignition. It is shown that the critical flame radius and the minimum ignition energy increase significantly with the Lewis number. Therefore, for transportation fuels with large Lewis numbers, blending of small molecule fuels or thermal and catalytic cracking will significantly reduce the minimum ignition energy.
Analysis of grid imprinting on geodesic spherical icosahedral grids Pedro S. Peixoto, Saulo R. M-090 S~ao Paulo, Brazil Abstract Numerical grid imprinting errors have often been observed in global atmospheric models on icosahedral grids. In this paper we analyse the sources of grid imprinting error related
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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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office511041clothAdvanced Materials Advanced Materials Find More Like3.3 PrintVulture
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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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh School footballHydrogenITLaboratoryImprovingPetroleum
Synthesis of spherical LiMnPO{sub 4}/C composite microparticles
Bakenov, Zhumabay [Department of Chemical Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552 (Japan)] [Department of Chemical Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552 (Japan); Taniguchi, Izumi, E-mail: taniguchi.i.aa@m.titech.ac.jp [Department of Chemical Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552 (Japan)] [Department of Chemical Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552 (Japan)
2011-08-15T23:59:59.000Z
Highlights: {yields} We could prepare LiMnPO{sub 4}/C composites by a novel preparation method. {yields} The LiMnPO{sub 4}/C composites were spherical particles with a mean diameter of 3.65 {mu}m. {yields} The LiMnPO{sub 4}/C composite cathode exhibited 112 mAh g{sup -1} at 0.05 C. {yields} It also showed a good rate capability up to 5 C at room temperature and 55 {sup o}C. -- Abstract: Spherical LiMnPO{sub 4}/C composite microparticles were prepared by a combination of spray pyrolysis and spray drying followed by heat treatment and examined as a cathode material for lithium batteries. The structure, morphology and electrochemical performance of the resulting spherical LiMnPO{sub 4}/C microparticles were characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electronic microscopy and standard electrochemical techniques. The final sample was identified as a single phase orthorhombic structure of LiMnPO{sub 4} and spherical powders with a geometric mean diameter of 3.65 {mu}m and a geometric standard deviation of 1.34. The electrochemical cells contained the spherical LiMnPO{sub 4}/C microparticles exhibited first discharge capacities of 112 and 130 mAh g{sup -1} at 0.05 C at room temperature and 55 {sup o}C, respectively. These also showed a good rate capability up to 5 C at room temperature and 55 {sup o}C.
Pacific Northwest National Laboratory
Pacific Northwest National Laboratory Operated by Battelle for the U.S. Department of Energy Northwest National Laboratory (PNNL) operated by Battelle Memorial Institute. Battelle has a unique contract
Argonne National Laboratory's Nondestructive
Kemner, Ken
Argonne National Laboratory's Nondestructive Evaluation Technologies NDE #12;Over45yearsexperienceinNondestructiveEvaluation... Argonne National Laboratory's world-renowned researchers have a proven the safe operationof advanced nuclear reactors. Argonne's World-Class Nondestructive Evaluation
Mentoring | Argonne National Laboratory
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
As one of the largest laboratories in the nation for science and engineering research, Argonne National Laboratory is home to some of the most prolific and well-renowned scientists...
National Energy Education Summit
Broader source: Energy.gov [DOE]
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...
Sandia National Laboratories: Facilities
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Laboratory (PSEL) National Supervisory Control and Data Acquisition (SCADA) Test Bed Center for Integrated Nanotechnologies (CINT) Distributed Energy Technologies Laboratory...
Broader source: Energy.gov [DOE]
High-resolution map produced by Oak Ridge National Laboratory showing hydropower resources throughout the United States.
National Nuclear Security Administration
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
FROM: SUBJECT: USIUK Memorandum of Understanding between National Nuclear Security Administration's (NNSA) Associate Administrator for Defense Nuclear Security (AADNS)...
Sandia National Laboratories: AREVA
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Concentrating Solar Power, Energy, Energy Storage, Facilities, National Solar Thermal Test Facility, News, News & Events, Partnership, Renewable Energy, Research &...
Sandia National Laboratories: National Rotor Testbed
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Energy, SWIFT, Systems Analysis, Wind Energy The National Rotor Testbed (NRT) team is examining the effect of airfoil choice on the final design of the new rotor for the Scaled...
NATIONAL HYDROGEN ENERGY ROADMAP
NATIONAL HYDROGEN ENERGY ROADMAP NATIONAL HYDROGEN ENERGY ROADMAP . . Toward a More Secure and Cleaner Energy Future for America Based on the results of the National Hydrogen Energy Roadmap Workshop to make it a reality. This Roadmap provides a framework that can make a hydrogen economy a reality
Markowitz, Alex; Nikutta, Robert
2014-01-01T23:59:59.000Z
We present an analysis of multi-timescale variability in line-of-sight X-ray absorbing gas as a function of optical classification in a large sample of Seyfert AGN to derive the first X-ray statistical constraints for clumpy-torus models. We systematically search for discrete absorption events in the vast archive of RXTE monitoring of dozens of nearby type I and Compton-thin type II AGN. We are sensitive to discrete absorption events due to clouds of full-covering, neutral or mildly ionized gas with columns <~ 10^(22-25) cm^-2 transiting the line of sight. We detect 12 eclipse events in 8 objects, roughly tripling the number previously published from this archive. Peak column densities span ~ 4-26 x 10^22 cm^-2. Event durations span hours to months. The column density profile for an eclipsing cloud in NGC 3783 is doubly spiked, possibly indicating a cloud that is being tidally sheared. We infer the clouds' distances from the black hole to span ~0.3 -140 x 10^4 R_g. In seven objects, the clouds' distances a...
Fate of Accidental Symmetries of the Relativistic Hydrogen Atom in a Spherical Cavity
Al-Hashimi, M H; Wiese, U -J
2015-01-01T23:59:59.000Z
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 ...
Non-Singular Spherically Symmetric Solution in Einstein-Scalar-Tensor Gravity
J. W. Moffat
2008-06-11T23:59:59.000Z
A static spherically symmetric metric in Einstein-scalar-tensor gravity theory with a scalar field potential $V[\\phi]$ is non-singular for all real values of the coordinates. It does not have a black hole event horizon and there is no essential singularity at the origin of coordinates. The weak energy condition $\\rho_\\phi > 0$ fails to be satisfied for $r\\lesssim 1.3r_S$ (where $r_S$ is the Schwarzschild radius) but the strong energy condition $\\rho_\\phi+3p_\\phi > 0$ is satisfied. The classical Einstein-scalar-tensor solution is regular everywhere in spacetime without a black hole event horizon. However, the violation of the weak energy condition may signal the need for quantum physics anti-gravity as $r\\to 0$. The non-singular static spherically symmetric solution is stable against the addition of ordinary matter.
Light-emitting diode spherical packages: an equation for the light transmission efficiency
Moreno, Ivan; Avendano-Alejo, Maximino; 10.1364/AO.49.000012
2011-01-01T23:59:59.000Z
Virtually all light-emitting diodes (LEDs) are encapsulated with a transparent epoxy or silicone-gel. In this paper we analyze the optical efficiency of spherical encapsulants. We develop a quasi-radiometric equation for the light transmission efficiency, which incorporates some ideas of Monte-Carlo ray tracing into the context of radiometry. The approach includes the extended source nature of the LED chip, and the chip radiance distribution. The equation is an explicit function of the size and the refractive index of the package, and also of several chip parameters such as shape, size, radiance, and location inside the package. To illustrate the use of this equation, we analyze several packaging configurations of practical interest; for example, a hemispherical dome with multiple chips, a flat encapsulation as a special case of the spherical package, and approximate calculations of an encapsulant with a photonic crystal LED or with a photonic quasi crystal LED. These calculations are compared with Monte-Carl...
T. Thiemann
1999-10-04T23:59:59.000Z
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
1999-10-04T23:59:59.000Z
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.
Marushka, Viktor; Zabeida, Oleg, E-mail: oleg.zabeida@polymtl.ca; Martinu, Ludvik [Engineering Physics Department, Polytechnique Montréal, P.O. Box 6079, Downtown station, Montreal, Quebec H3C 3A7 (Canada)
2014-11-01T23:59:59.000Z
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.
Adler, Thomas A. (Corvallis, OR)
1996-01-01T23:59:59.000Z
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.
A spherically symmetric and stationary universe from a weak modification of general relativity
Christian Corda; Herman J. Mosquera Cuesta
2009-04-01T23:59:59.000Z
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.
The Energy Distribution in a Static Spherically Symmetric Nonsingular Black Hole Space-Time
I. Radinschi
2000-08-14T23:59:59.000Z
We calculate the energy distribution in a static spherically symmetric nonsingular black hole space-time by using the Tolman's energy-momentum complex. All the calculations are performed in quasi-Cartesian coordinates. The energy distribution is positive everywhere and be equal to zero at origin. We get the same result as obtained by Y-Ching Yang by using the Einstein's and Weinberg's prescriptions.
Why Professor Richard Feynman was upset solving the Laplace equation for spherical waves?
Anzor Khelashvili; Teimuraz Nadareishvili
2013-02-04T23:59:59.000Z
We take attention to the singular behavior of the Laplace operator in spherical coordinates, which was established in our earlier work. This singularity has many non-trivial consequences. In this article we consider only the simplest ones, which are connected to the solution of Laplace equation in Feynman classical books and Lectures. Feynman was upset looking in his derived solutions, which have a fictitious singular behavior at the origin. We show how these inconsistencies can be avoided.
Thermal stability of a spherical shell heated by convection and cooled by boiling
Qaim-Maqami, Hassan
1973-01-01T23:59:59.000Z
such high heat transfer rates by forced convection would require extremely high veloc- ities with subsequent high pressure dropsy With nuclee, boiling, however, such high heat transfe. rates an be obtained at much smaller velocities. Boiling heat...THERMAL STABILITY OF A. SPHERICAL SHELL HEATED BY CONVECTION AND COOLED BY BOILING A Thesis HASSAN @AIM-MAQAMI Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER...
Casimir energy for self-interacting scalar field in a spherical shell
M. R. Setare; R. Mansouri
2002-01-27T23:59:59.000Z
In this paper we calculate the Casimir energy for spherical shell with massless self-interacting scalar filed which satisfying Dirichlet boundary conditions on the shell. Using zeta function regularization and heat kernel coefficients we obtain the divergent contributions inside and outside of Casimir energy. The effect of self-interacting term is similar with existing of mass for filed. In this case some divergent part arises. Using the renormalization procedure of bag model we can cancel these divergent parts.
Francine Luppé; Jean-Marc Conoir; Andrew N. Norris
2011-10-06T23:59:59.000Z
The dispersion relation is derived for the coherent waves in fluid or elastic media supporting viscous and thermal effects and containing randomly distributed spherical scatterers. The formula obtained is the generalization of Lloyd and Berry's [Proc. Phys. Soc. Lond. 91, 678-688, 1067], the latter being limited to fluid host media, and it is the three-dimensional counterpart of that derived by Conoir and Norris [Wave Motion 47, 183-197, 2010] for cylindrical scatterers in an elastic host medium.
A special exact spherically symmetric solution in f(T) gravity theories
Nashed, G G L
2015-01-01T23:59:59.000Z
A non-diagonal spherically symmetric tetrad field, involving four unknown functions of radial coordinate $r$, is applied to the equations of motion of f(T) gravity theory. A special exact vacuum solution with one constant of integration is obtained. The scalar torsion related to this special solution vanishes. To understand the physical meaning of the constant of integration we calculate the energy associated with this solution and show how it is related to the gravitational mass of the system.
A special exact spherically symmetric solution in f(T) gravity theories
G. G. L. Nashed
2015-02-17T23:59:59.000Z
A non-diagonal spherically symmetric tetrad field, involving four unknown functions of radial coordinate $r$, is applied to the equations of motion of f(T) gravity theory. A special exact vacuum solution with one constant of integration is obtained. The scalar torsion related to this special solution vanishes. To understand the physical meaning of the constant of integration we calculate the energy associated with this solution and show how it is related to the gravitational mass of the system.
Decay of Dirac Massive Hair in the Background of Spherical Black Hole
Rafa? Moderski; Marek Rogatko
2008-05-06T23:59:59.000Z
The intermediate and late-time behaviour of massive Dirac hair in the static spherically symmetric black hole spacetime was studied. It was revealed that the intermediate asymptotic pattern of decay of massive Dirac spinor hair is dependent on the mass of the field under consideration as well as the multiple number of the wave mode. The long-lived oscillatory tail observed at timelike infinity in the considered background decays slowly as t^{-5/6}.
Spherically symmetric self-similar solutions and their astrophysical and cosmological applications
B. J. Carr
2000-03-02T23:59:59.000Z
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.
A hyper-spherical adaptive sparse-grid method for high-dimensional discontinuity detection
Zhang, Guannan [ORNL; Webster, Clayton G [ORNL; Gunzburger, Max D [ORNL; Burkardt, John V [ORNL
2014-03-01T23:59:59.000Z
This work proposes and analyzes a hyper-spherical adaptive hi- erarchical sparse-grid method for detecting jump discontinuities of functions in high-dimensional spaces is proposed. The method is motivated by the the- oretical and computational inefficiencies of well-known adaptive sparse-grid methods for discontinuity detection. Our novel approach constructs a func- tion representation of the discontinuity hyper-surface of an N-dimensional dis- continuous quantity of interest, by virtue of a hyper-spherical transformation. Then, a sparse-grid approximation of the transformed function is built in the hyper-spherical coordinate system, whose value at each point is estimated by solving a one-dimensional discontinuity detection problem. Due to the smooth- ness of the hyper-surface, the new technique can identify jump discontinuities with significantly reduced computational cost, compared to existing methods. Moreover, hierarchical acceleration techniques are also incorporated to further reduce the overall complexity. Rigorous error estimates and complexity anal- yses of the new method are provided as are several numerical examples that illustrate the effectiveness of the approach.
Sandia National Laboratories: Renewable Energy
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10, 2012, in Concentrating Solar Power, EC, National Solar Thermal Test Facility, Renewable Energy Dr. David Danielson visited Sandia National Laboratories and toured the National...
Cognitive Informatics, Pacific Northwest National Laboratory | National
National Nuclear Security Administration (NNSA)
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA groupTubahq.na.gov Office of theNuclearNanotechnologies | NationalNuclear
Sandia National Laboratories | National Nuclear Security Administration
National Nuclear Security Administration (NNSA)
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA Approved: 5-13-14 FEDERALAmerica HighSTART Signed | National|Operations /
Sandia National Laboratories | National Nuclear Security Administration
National Nuclear Security Administration (NNSA)
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA Approved: 5-13-14 FEDERALAmerica HighSTART Signed | National|Operations /Allison
Sandia National Laboratories | National Nuclear Security Administration
National Nuclear Security Administration (NNSA)
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA Approved: 5-13-14 FEDERALAmerica HighSTART Signed | National|Operations
Sandia National Laboratories | National Nuclear Security Administration
National Nuclear Security Administration (NNSA)
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA Approved: 5-13-14 FEDERALAmerica HighSTART Signed | National|OperationsSandia
Sandia National Laboratory | National Nuclear Security Administration
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: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del Sol HomeFacebook Twitter YouTubeCenters:FacebookContractor/Bidder| National Nuclear
Dale M. Meade 2002 Fusion Summer Study
and Technolgy Feasibility Electric Power Feasibility Economic Feasibility Spherical Torus, RFP Spheromak, FRC Torus, RFP Spheromak, FRC, MTF Three Large Tokamaks JT-60 U JET TFTR Several Large Facilities FIRE KSTAR
Employment at National Laboratories
E. S. Peterson; C. A. Allen
2007-04-01T23:59:59.000Z
Scientists enter the National Laboratory System for many different reasons. For some, faculty positions are scarce, so they take staff-scientist position at national laboratories (i.e. Pacific Northwest, Idaho, Los Alamos, and Brookhaven). Many plan to work at the National Laboratory for 5 to 7 years and then seek an academic post. For many (these authors included), before they know it it’s 15 or 20 years later and they never seriously considered leaving the laboratory system.
Sandia National Laboratories: AMI
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Manufacturing Initiative (AMI) is a multiple-year, 3-way collaboration among TPI Composites, Iowa State University, and Sandia National Laboratories. The goal of this...
Sandia National Laboratories: Microgrid
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to solve many of the nation's most complex challenges in satisfying its electric energy needs. Initial focus has been on enabling resilient and reliable performance when...
None
2013-03-01T23:59:59.000Z
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.
Sandia National Laboratories: Photovoltaics
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Security National Solar Thermal Test Facility NSTTF Nuclear Energy photovoltaic Photovoltaics PV Renewable Energy solar Solar Energy solar power Solar Research Solid-State...
Sandia National Laboratories: Photovoltaics
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
2013 Inverter Reliability Workshop On May 31, 2013, in Hosted by Sandia National Laboratories and the Electric Power Research Institute (EPRI) Inverter reliability drives project...
Sandia National Laboratories: photovoltaic
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photovoltaic Microsystems Enabled Photovoltaics (MEPV) On April 14, 2011, in About MEPV Flexible MEPV MEPV Publications MEPV Awards Researchers at Sandia National Laboratories are...
News | Argonne National Laboratory
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Researchers from Argonne National Laboratory modeled several scenarios to add more solar power to the electric grid, using real-world data from the southwestern power...
Sandia National Laboratories: SPI
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Conference, the Department of Energy (DOE), the Electric Power Research Instisute (EPRI), Sandia National Laboratories, ... Last Updated: September 10, 2012 Go To Top ...
Sandia National Laboratories: IRED
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SMART Grid, Solar Sandia National Laboratories, the Electric Power Research Institute (EPRI) and European Distributed Energies Research Laboratories (DERlab) have organized a...
Sandia National Laboratories: PV
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... Photovoltaic Technology and Tour of PV Test Facilities On February 12, 2013, in The Photovoltaics and Distributed Systems Integration Department at Sandia National...
Sandia National Laboratories: Climate
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Climate A Model for the Nation: Promoting Education and Innovation in Vermont's Electricity Sector On May 8, 2012, in Climate, Customers & Partners, Energy, Energy Surety,...
Sandia National Laboratories: Energy
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Summit and Technology Forum will convene the ... A Model for the Nation: Promoting Education and Innovation in Vermont's Electricity Sector On May 8, 2012, in Climate,...
Sandia National Laboratories: Infrastructure
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Quallion Eaton Corp. Air Products ExxonTonen ... A Model for the Nation: Promoting Education and Innovation in Vermont's Electricity Sector On May 8, 2012, in Climate,...
Sandia National Laboratories: CETI
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CETI A Model for the Nation: Promoting Education and Innovation in Vermont's Electricity Sector On May 8, 2012, in Climate, Customers & Partners, Energy, Energy Surety,...
Sandia National Laboratories: Vermont
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Vermont A Model for the Nation: Promoting Education and Innovation in Vermont's Electricity Sector On May 8, 2012, in Climate, Customers & Partners, Energy, Energy Surety,...
Sandia National Laboratories: Publications
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This public benchmark represents analysis ... A Model for the Nation: Promoting Education and Innovation in Vermont's Electricity Sector On May 8, 2012, in Climate,...
Sandia National Laboratories: Workshops
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Geoscience, Climate and Consequence Effect at Sandia National Laboratories presented on "Hydraulic Fracturing: Role of Government-Sponsored R&D." Marianne's presentation was part...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
place huge demand on the nation's electrical grid, while the increased use of wind and solar energy will challenge the grid's ability to provide a stable electrical supply...
Sandia National Laboratories: publications
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Laboratories, August 2010. 2009 Adrian R. Chavez, Position Paper: Protecting Process Control Systems against Lifecycle Attacks Using Trust Anchors Sandia National ... Page 1...
None
2010-01-01T23:59:59.000Z
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.
Transportation | Argonne National Laboratory
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Patented technologies created by Argonne - which includes solutions for the smart grid, electric vehicles, emissions control and more - will help our nation conserve energy and...
Sandia National Laboratories: performance
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performance Photovoltaic (PV) Regional Test Center (RTC) Website Goes Live On February 26, 2013, in Energy, National Solar Thermal Test Facility, News, News & Events, Partnership,...
Los Alamos National Laboratory
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the first results of joint work by scientists from Lawrence Berkeley, Pacific Northwest, Savannah River, and Los Alamos national laboratories at the Savannah River Site to model...
Sandia National Laboratories: Combustion
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security and economic prosperity. Energy security research at Sandia seeks to address key challenges facing our nation and the world. We work ... Page 2 of 212 Last...
National Laboratory Photovoltaics Research
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DOE supports photovoltaic (PV) research and development and facilities at its national laboratories to accelerate progress toward achieving the SunShot Initiative's technological and economic...
Discoveries | Argonne National Laboratory
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nation's pressing scientific and technological challenges. Robert Fischetti and Janet Smith developed the first micro X-ray beam for structural biology at Argonne's Advanced...
Sandia National Laboratories: Solar
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Photovoltaic (PV) Regional Test Center (RTC) Website Goes Live On February 26, 2013, in Energy, National Solar Thermal Test Facility, News, News & Events, Partnership,...
Sandia National Laboratories: photostability
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Updated: May 23, 2013 Go To Top Exceptional service in the national interest EC About Energy and Climate (EC) Energy Security Climate Security Infrastructure Security Energy...
Sandia National Laboratories: CCT
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Updated: May 23, 2013 Go To Top Exceptional service in the national interest EC About Energy and Climate (EC) Energy Security Climate Security Infrastructure Security Energy...
Sandia National Laboratories: QY
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Updated: May 23, 2013 Go To Top Exceptional service in the national interest EC About Energy and Climate (EC) Energy Security Climate Security Infrastructure Security Energy...
Los Alamos National Laboratory
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23, 2013-Nearly 400 Los Alamos National Laboratory employees on 47 teams received Pollution Prevention awards for protecting the environment and saving taxpayers more than 8...
Sandia National Laboratories: HRSAM
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and the National Renewable Energy Laboratory (NREL) announce the publication of two new Hydrogen Fueling Infrastructure Research and Station Technology (H2FIRST) reports on...
National Women's History Month
Broader source: Energy.gov [DOE]
NATIONAL WOMEN’S HISTORY MONTH is an annual declared month that highlights the contributions of women to events in history and contemporary society.
Sandia National Laboratories: NASA
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National Laboratories (partnering with Northrup Grumman Aerospace Systems and the University of Michigan) has developed a solar electric propulsion concept capable of a wide...
Sandia National Laboratories: Energy
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at a critical juncture where pressing issues in energy security, climate change, and economic competitiveness are converging. Aggressive national goals for reducing petroleum use...
ARGONNE NATIONAL LABORATORY May
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ARGONNE NATIONAL LABORATORY May 9, 1994 Light Source Note: LS234 Comparison of the APS and UGIMAG Helmholtz Coil Systems David W. Carnegie Accelerator Systems Division Advanced...
Licensing | Argonne National Laboratory
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(TDC) Division negotiates and manages license agreements on behalf of UChicago Argonne, LLC, which operates Argonne National Laboratory for the U.S. Department of Energy....
Procurement | Argonne National Laboratory
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Procurement More than 150 attend second joint Argonne-Fermilab small business fairSeptember 2, 2014 On Thursday, Aug. 28, Illinois' two national laboratories - Argonne and Fermi...
Procurement | Argonne National Laboratory
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Video "Doing business with Argonne and Fermi national labs" - Aug. 21, 2013 Procurement Argonne spends approximately 300,000,000 annually through procurements to a diverse group...
Research | Argonne National Laboratory
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our dependence on imported energy and to enhance our national security. In addition, Argonne provides many ways for researchers from academia, industry and other government...
Sandia National Laboratories: NSTTF
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& Events, Partnership, Renewable Energy, Solar, Solar Newsletter SolarReserve is testing engineering units at the National Solar Thermal Test Facility (NSTTF) operated by Sandia....
Los Alamos National Laboratory
National Nuclear Security Administration (NNSA)
for national defense and homeland security programs; and U.S. Department of Energy (DOE) waste management activities. The Plutonium Facility at Technical Area 55 (TA-55) is...
Sandia National Laboratories: solar
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Gas Sectors in the United States View all EC Publications Related Topics Concentrating Solar Power CRF CSP EFRC Energy Energy Efficiency Energy Security National Solar Thermal...
Sandia National Laboratories: Partnership
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Armstrong using deep level optical spectroscopy to investigate defects in the m-plane GaN. Jim is a professor ... Vermont and Sandia National Laboratories Announce Energy...
Los Alamos National Laboratory
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this tenth member of our National Centers for Systems Biology program," said James Anderson, who oversees systems biology awards at NIGMS. "The new center will apply...
National Park Service- Yellowstone National Park, Wyoming
Broader source: Energy.gov [DOE]
Yellowstone National Park, Wyoming, has many historical sites within its boundaries. One of these is the Lamar Buffalo Ranch, a ranch that was set up in the early 1900s to breed buffalo for replacement stock within the park during a time when their numbers were very low. The ranch buildings are currently being used by the Yellowstone Association Institute for ecology classes.
Xudong Liang; Shengqiang Cai
2015-05-29T23:59:59.000Z
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.
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...
National Research Council Canada
Fleming, Michael W.
National Research Council Canada Institute for Information Technology Conseil national de recherches Canada Institut de technologie de l'information Determining Internet Users' Values for Private in The Second Annual Conference on Privacy, Security and Trust (PST'04). Fredericton, New Brunswick, Canada
The National Cancer Institute,
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
National Osteoporosis Prevention Month
MAY National Osteoporosis Prevention Month JUNE National Dairy Month Texas AgriLife Extension - Bone Health Power Point # P4-1 Eat Smart for Bone Health # P4-2 Osteoporosis Disease Statistics # P4-3 Osteoporosis = Porous Bones # P4-4 Risk Factors # P4-5 Risk Factors (continued) # P4-6 Steps to Prevention # P4
INDIAN NATIONAL SCIENCE ACADEMY
Srinivasan, N.
INDIAN NATIONAL SCIENCE ACADEMY Science academies play a crucial role in promoting, recognizing and bring out proceedings and monographs. The academies promote public awareness and understanding the country. In this section the growth of the Indian National Science Academy and its functions
Overview of the preliminary safety analysis of the National Ignition Facility
Brereton, S.; McLouth, L.; Odell, B. [Lawrence Livermore National Lab., CA (United States)] [and others] [Lawrence Livermore National Lab., CA (United States); and others
1997-06-01T23:59:59.000Z
The National Ignition Facility (NIF) is a proposed U.S. Department of Energy inertial confinement laser fusion facility. The candidate sites for locating the NIF are: Los Alamos National Laboratory, Sandia National Laboratory, New Mexico, the Nevada Test Site, and Lawrence Livermore National Laboratory (LLNL), the preferred site. The NIF will operate by focusing 192 individual laser beams onto a tiny deuterium-tritium target located at the center of a spherical target chamber. The NIF has been classified as a low hazard, radiological facility on the basis of a preliminary hazards analysis and according to the DOE methodology for facility classification. This requires that a safety analysis report be prepared under DOE Order 5481.1B, Safety Analysis and Review System. A Preliminary Safety Analysis Report (PSAR) has been approved, which documents and evaluates the safety issues associated with the construction, operation, and decommissioning of the NIF. 10 refs., 6 figs., 4 tabs.
Spherical Shell Cosmological Model and Uniformity of Cosmic Microwave Background Radiation
Branislav Vlahovic
2012-07-06T23:59:59.000Z
Considered is spherical shell as a model for visible universe and parameters that such model must have to comply with the observable data. The topology of the model requires that motion of all galaxies and light must be confined inside a spherical shell. Consequently the observable universe cannot be defined as a sphere centered on the observer, rather it is an arc length within the volume of the spherical shell. The radius of the shell is 4.46 $\\pm$ 0.06 Gpc, which is for factor $\\pi$ smaller than radius of a corresponding 3-sphere. However the event horizon, defined as the arc length inside the shell, has the size of 14.0 $\\pm$ 0.2 Gpc, which is in agreement with the observable data. The model predicts, without inflation theory, the isotropy and uniformity of the CMB. It predicts the correct value for the Hubble constant $H_0$ = 67.26 $\\pm$ 0.90 km/s/Mpc, the cosmic expansion rate $H(z)$, and the speed of the event horizon in agreement with observations. The theoretical suport for shell model comes from general relativity, curvature of space by mass, and from holographic principle. The model explains the reason for the established discrepancy between the non-covariant version of the holographic principle and the calculated dimensionless entropy $(S/k)$ for the visible universe, which exceeds the entropy of a black hole. The model is in accordance with the distribution of radio sources in space, type Ia data, and data from the Hubble Ultra Deep Field optical and near-infrared survey.
Classic tests of General Relativity described by brane-based spherically symmetric solutions
R. R. Cuzinatto; P. J. Pompeia; M. de Montigny; F. C. Khanna; J. M. Hoff da Silva
2014-09-03T23:59:59.000Z
We discuss a way to obtain information about higher dimensions from observations by studying a brane-based spherically symmetric solution. The three classic tests of General Relativity are analyzed in details: the perihelion shift of the planet Mercury, the deflection of light by the Sun, and the gravitational redshift of atomic spectral lines. The braneworld version of these tests exhibits an additional parameter $b$ related to the fifth-coordinate. This constant $b$ can be constrained by comparison with observational data for massive and massless particles.
Explicit Solution of Worst-Case Secrecy Rate for MISO Wiretap Channels with Spherical Uncertainty
Li, Jiangyuan
2011-01-01T23:59:59.000Z
A multiple-input single-output (MISO) wiretap channel model is considered, that includes a multi-antenna transmitter, a single-antenna legitimate receiver and a single-antenna eavesdropper. For the scenario in which spherical uncertainty for both the legitimate and the eavesdropper channels is included, the problem of finding the optimal input covariance that maximizes the worst-case secrecy rate subject to a power constraint, is considered, and an explicit expression for the maximum worst-case secrecy rate is provided.
Machine imparting complex rotary motion for lapping a spherical inner diameter
Carroll, T.A.; Yetter, H.H.
1985-01-30T23:59:59.000Z
An apparatus for imparting complex rotary motion is used to lap an inner spherical diameter surface of a workpiece. A lapping tool consists of a dome and rod mounted along the dome's vertical axis. The workpiece containing the lapping tool is held in a gimbal which uses power derived from a secondary takeoff means to impart rotary motion about a horizontal axis. The gimbal is rotated about a vertical axis by a take means while mounted at a radially outward position on a rotating arm.
Martin Schaden
2010-06-16T23:59:59.000Z
The leading semiclassical estimates of the electromagnetic Casimir stresses on a spherical and a cylindrical metallic shell are within 1% of the field theoretical values. The electromagnetic Casimir energy for both geometries is given by two decoupled massless scalars that satisfy conformally covariant boundary conditions. Surface contributions vanish for smooth metallic boundaries and the finite electromagnetic Casimir energy in leading semiclassical approximation is due to quadratic fluctuations about periodic rays in the interior of the cavity only. Semiclassically the non-vanishing Casimir energy of a metallic cylindrical shell is almost entirely due to Fresnel diffraction.
On the non-relativistic limit of the spherically symmetric Einstein-Vlasov-Maxwell system
P. Noundjeu
2005-08-19T23:59:59.000Z
The Einstein-Vlasov-Maxwell (EVM) system can be viewed as a relativistic generalization of the Vlasov-Poisson (VP) system. As it is proved below, one of nice property obeys by the first system is that the strong energy condition holds and this allows to conclude that the above system is physically viable. We show in this paper that in the context of spherical symmetry, solutions of the perturbed (EVM) system by $\\gamma := 1/c^{2}$, $c$ being the speed of light, exist and converge uniformly in $L^{\\infty}$-norm, as $c$ goes to infinity on compact time intervals to solutions of the non-relativistic (VP) system.
Instability localized at the inner surface of an imploding spherical shell
Han, S.J.
1983-01-01T23:59:59.000Z
It is shown that in an imploding spherical shell the surface instabilities are of two different types. The first, which occurs at the outer surfaces, is the Rayleigh-Taylor instability. The second instability occurs at the inner surface. This latter instability is not as disruptive as R-T modes, but it has three basic properties which differ considerably from those of the R-T instability: (1) it is oscillatory at early times; (2) it grows faster in the long wavelength modes; (3) it depends on the equation of state. It is further shown that this new instability is driven by amplified sound waves in the shell.
In-medium nucleon-nucleon cross-sections with non-spherical Pauli blocking
L. White; F. Sammarruca
2014-06-14T23:59:59.000Z
We present a formalism to solve the Bethe-Goldstone scattering equation without the use of partial wave expansion which is alternative to the one we developed in a previous work. The present approach is more suitable for the calculation of in-medium nucleon-nucleon cross sections, which are the focal point of this paper. The impact of removing the spherical approximation on the angle and energy dependence of, particularly, in-medium proton-proton and proton-neutron differential cross sections is discussed along with its potential implication.
Testing the neutrality of matter by acoustic means in a spherical resonator
Bressi, G.; Carugno, G.; Della Valle, F.; Galeazzi, G.; Ruoso, G.; Sartori, G. [INFN, Sezione di Pavia, Via U. Bassi 6, I-27100 Pavia (Italy); INFN, Sezione di Padova, Via F. Marzolo 8, I-35131 Padova (Italy); Dipartimento di Fisica, Universita di Trieste and INFN, Sezione di Trieste, Via A. Valerio 2, I-34127 Trieste (Italy); INFN, Laboratori Nazionali di Legnaro, Viale dell'Universita 2, I-35020 Legnaro (PD) (Italy); INFN, Sezione di Padova and Dipartimento di Fisica, Universita di Padova, Via F. Marzolo 8, I-35131 Padova (Italy)
2011-05-15T23:59:59.000Z
Measurements to test the neutrality of matter by acoustic means are reported. The apparatus is based on a spherical capacitor filled with gaseous SF{sub 6} excited by an oscillating electric field. The apparatus has been calibrated measuring the electric polarizability. Assuming charge conservation in the {beta} decay of the neutron, the experiment gives a limit of {epsilon}{sub p-e} < or approx. 1x10{sup -21} for the electron-proton charge difference, the same limit holding for the charge of the neutron. Previous measurements are critically reviewed and found to be inaccurate.
PRECONDITIONED BI-CONJUGATE GRADIENT METHOD FOR RADIATIVE TRANSFER IN SPHERICAL MEDIA
Anusha, L. S.; Nagendra, K. N. [Indian Institute of Astrophysics, Koramangala, Bangalore 560 034 (India); Paletou, F.; Leger, L. [Laboratoire d'Astrophysique de Toulouse-Tarbes, Universite de Toulouse, CNRS, 14 Ave. E. Belin, 31400 Toulouse (France)
2009-10-10T23:59:59.000Z
A robust numerical method called the Preconditioned Bi-Conjugate Gradient (Pre-BiCG) method is proposed for the solution of the radiative transfer equation in spherical geometry. A variant of this method called Stabilized Preconditioned Bi-Conjugate Gradient (Pre-BiCG-STAB) is also presented. These are iterative methods based on the construction of a set of bi-orthogonal vectors. The application of the Pre-BiCG method in some benchmark tests shows that the method is quite versatile, and can handle difficult problems that may arise in astrophysical radiative transfer theory.
ABAREX -- A neutron spherical optical-statistical-model code -- A user`s manual
Smith, A.B. [ed.; Lawson, R.D.
1998-06-01T23:59:59.000Z
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.
SPHERICALLY SYMMETRIC NLTE MODEL ATMOSPHERES OF HOT HYDROGEN-HELIUM FIRST STARS
Kubat, Jiri [Astronomicky ustav, Akademie ved Ceske Republiky, CZ-251 65 Ondrejov (Czech Republic)
2012-12-15T23:59:59.000Z
We present results of our calculations of NLTE model stellar atmospheres for hot Population III stars composed of hydrogen and helium. We use our own computer code for the calculation of spherically symmetric NLTE model atmospheres in hydrostatic and radiative equilibrium. The model atmospheres are then used for the calculation of emergent fluxes. These fluxes serve to evaluate the flow of high-energy photons for energies higher than ionization energies of hydrogen and helium, the so-called ionizing photon fluxes. We also present the time evolution of the ionizing photon fluxes.
On spherically symmetric metric satisfying the positive kinetic energy coordinate condition
T. Mei
2008-02-28T23:59:59.000Z
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.
Unconstrained hyperboloidal evolution of black holes in spherical symmetry with GBSSN and Z4c
Alex Vañó-Viñuales; Sascha Husa
2014-12-15T23:59:59.000Z
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.
National Institutes of Health National Institute of Mental Health
Baker, Chris I.
National Institutes of Health National Institute of Mental Health Department of Health and HumanNational Institute of Mental Health Division of Intramural Research Programs http://intramural.nimh.nih.gov/ [NIMH of Fellowship Training] National Institutes of Health National Institute of Mental Health Department of Health
NSTX-U Digital Coil Protection System Software Detailed Design
none,
2014-06-01T23:59:59.000Z
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.