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they are not comprehensive nor are they the most current set.
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1

Direct Imaging of Antiferromagnetic Vortex States  

NLE Websites -- All DOE Office Websites (Extended Search)

unique properties for the AFM vortex state. Recently, a research team from Berkeley, Korea, and China has taken the first direct image of an AFM vortex in multilayered magnetic...

2

Twisted vortex state  

E-Print Network (OSTI)

We study a twisted vortex bundle where quantized vortices form helices circling around the axis of the bundle in a "force-free" configuration. Such a state is created by injecting vortices into rotating vortex-free superfluid. Using continuum theory we determine the structure and the relaxation of the twisted state. This is confirmed by numerical calculations. We also present experimental evidence of the twisted vortex state in superfluid 3He-B.

V. B. Eltsov; A. P. Finne; R. Hanninen; J. Kopu; M. Krusius; M. Tsubota; E. V. Thuneberg

2006-02-28T23:59:59.000Z

3

Original articles: Vortex states in axially symmetric superconductors in applied magnetic field  

Science Conference Proceedings (OSTI)

We solve analytically the linearized Ginzburg-Landau (GL) equation in the presence of an uniform magnetic field with cylindrical boundary conditions. The solution of the non-linear GL equation is provided as an expansion in the basis of linearized solutions. ... Keywords: Axial magnetic field, Mesoscopic superconductivity, Nonlinear Ginzburg-Landau equation, Vortex

Andrei Ludu; Milorad V. Miloševi?; Francois M. Peeters

2012-03-01T23:59:59.000Z

4

Direct Imaging of Antiferromagnetic Vortex States  

NLE Websites -- All DOE Office Websites (Extended Search)

Direct Imaging of Antiferromagnetic Vortex States Print Direct Imaging of Antiferromagnetic Vortex States Print Magnetic materials are characterized by the ordering of electron spins, with nearest-neighbor spins parallel to each other in ferromagnetic (FM) materials and antiparallel to each other in antiferromagnetic (AFM) materials. As the size of a magnetic system is reduced to micron scale, it has been shown that the spins in an FM microstructure can curl around to form a magnetic vortex state. While there has been intensive activity in the study of vortex states in FM disks, there has been no direct observation of such states in an AFM microstructure, although theory predicts many interesting and unique properties for the AFM vortex state. Recently, a research team from Berkeley, Korea, and China has taken the first direct image of an AFM vortex in multilayered magnetic disk structures using x-ray magnetic linear dichroism (XMLD) and photoemission electron microscopy (PEEM) at ALS Beamlines 4.0.2 and 11.0.1 , respectively. The experiments observed two types of AFM vortices, one of which has no analogue in FM vortices.

5

Direct Imaging of Antiferromagnetic Vortex States  

NLE Websites -- All DOE Office Websites (Extended Search)

Direct Imaging of Antiferromagnetic Vortex States Print Direct Imaging of Antiferromagnetic Vortex States Print Magnetic materials are characterized by the ordering of electron spins, with nearest-neighbor spins parallel to each other in ferromagnetic (FM) materials and antiparallel to each other in antiferromagnetic (AFM) materials. As the size of a magnetic system is reduced to micron scale, it has been shown that the spins in an FM microstructure can curl around to form a magnetic vortex state. While there has been intensive activity in the study of vortex states in FM disks, there has been no direct observation of such states in an AFM microstructure, although theory predicts many interesting and unique properties for the AFM vortex state. Recently, a research team from Berkeley, Korea, and China has taken the first direct image of an AFM vortex in multilayered magnetic disk structures using x-ray magnetic linear dichroism (XMLD) and photoemission electron microscopy (PEEM) at ALS Beamlines 4.0.2 and 11.0.1 , respectively. The experiments observed two types of AFM vortices, one of which has no analogue in FM vortices.

6

Direct Imaging of Antiferromagnetic Vortex States  

NLE Websites -- All DOE Office Websites (Extended Search)

Direct Imaging of Antiferromagnetic Vortex States Print Direct Imaging of Antiferromagnetic Vortex States Print Magnetic materials are characterized by the ordering of electron spins, with nearest-neighbor spins parallel to each other in ferromagnetic (FM) materials and antiparallel to each other in antiferromagnetic (AFM) materials. As the size of a magnetic system is reduced to micron scale, it has been shown that the spins in an FM microstructure can curl around to form a magnetic vortex state. While there has been intensive activity in the study of vortex states in FM disks, there has been no direct observation of such states in an AFM microstructure, although theory predicts many interesting and unique properties for the AFM vortex state. Recently, a research team from Berkeley, Korea, and China has taken the first direct image of an AFM vortex in multilayered magnetic disk structures using x-ray magnetic linear dichroism (XMLD) and photoemission electron microscopy (PEEM) at ALS Beamlines 4.0.2 and 11.0.1 , respectively. The experiments observed two types of AFM vortices, one of which has no analogue in FM vortices.

7

Magnetic Vortex Core Reversal by Low-Field Excitations  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnetic Vortex Core Reversal by Magnetic Vortex Core Reversal by Low-Field Excitations Magnetic Vortex Core Reversal by Low-Field Excitations Print Wednesday, 28 March 2007 00:00 In micrometer-sized magnetic thin films, the magnetization typically adopts an in-plane, circular configuration known as a magnetic vortex. At the vortex core, the magnetization turns sharply out of the plane, pointing either up or down. Magnetic data storage based on this binary phenomenon is an intriguing concept, but it would require the ability to flip the vortex cores on demand. Because these structures are highly stable, very strong magnetic fields of around half a tesla (approximately one-third the field of the strongest permanent magnet) were previously thought to be necessary to accomplish this. At the ALS, a team of researchers from Germany, Belgium, and the U.S. has used time-resolved scanning transmission x-ray microscopy (STXM) to observe vortex motion and demonstrate the feasibility of using weak magnetic fields as low as 1.5 millitesla (mT) to reverse the direction of a vortex core. The observed switching mechanism, which can be understood within the framework of micromagnetic theory, gives insights into basic magnetization dynamics and their possible application to data storage technologies.

8

A numerical study of steady-state vortex configurations and vortex pinning in type-II superconductors  

E-Print Network (OSTI)

In part I, a numerical study of the mixed states in a mesoscopic type-II superconducting cylinder is described. Steady-state configurations and transient behavior of the magnetic vortices for various values of the applied magnetic field H are presented. Transitions between different multi-vortex states as H is changed is demonstrated by abrupt changes in vortex configurations and jumps in the B vs H plot. An efficient scheme to determine the equilibrium vortex configuration in a mesoscopic system at any given applied field, not limited to the symmetry of the system, is devised and demonstrated. In part II, a superconducting thin film is subject to a non-uniform magnetic field from a vertical magnetic dipole, consisting of two magnetic monopoles of opposite charges. For a film with constant thickness and with no pins, it has been found that the film carries two pairs of vortex-antivortex in the steady state in the imposed flux range of 2.15 < (Phi)+ < 2.90 (in units of flux quantum) and no vortex at all for (Phi)+ <= 2.15. Transitions from a superconducting state with 3 pairs of vortex-antivortex to one with 2 pairs, where a pair of vortex-antivortex annihilates, have been observed in the pseudo-time sequence. With a perturbation with antidots (holes), vortexantivortex pair has been created for lower magnetic fluxes down to (Phi)+ = 1.3. In the sample of size 16(Xi) x 16(Xi), the attraction force between the vortex and antivortex always dominates over the pinning force, so that they eventually come out of pins, move toward each other, and annihilate each other. The annihilation rate, measured with time taken for the annihilation, is reduced noticeably by the increase of the distance between pins, or the increase in the pin size. A simulation of the magnetic vortex pinning in the sample of size 32(Xi) x 32(Xi) suggests we are likely to achieve pinning of the vortex-antivortex pair with the sample size around this and vortex-antivortex separation of 22(Xi). Using this sample as a template, the maximum density of pinned vortices achievable is calculates to be about 7.6 x 10^14 vortices/m2 for (Xi) =~ 1.6A°.

Kim, Sangbum

2004-12-01T23:59:59.000Z

9

Magnetic Vortex Core Reversal by Low-Field Excitations  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnetic Vortex Core Reversal by Low-Field Excitations Print Magnetic Vortex Core Reversal by Low-Field Excitations Print In micrometer-sized magnetic thin films, the magnetization typically adopts an in-plane, circular configuration known as a magnetic vortex. At the vortex core, the magnetization turns sharply out of the plane, pointing either up or down. Magnetic data storage based on this binary phenomenon is an intriguing concept, but it would require the ability to flip the vortex cores on demand. Because these structures are highly stable, very strong magnetic fields of around half a tesla (approximately one-third the field of the strongest permanent magnet) were previously thought to be necessary to accomplish this. At the ALS, a team of researchers from Germany, Belgium, and the U.S. has used time-resolved scanning transmission x-ray microscopy (STXM) to observe vortex motion and demonstrate the feasibility of using weak magnetic fields as low as 1.5 millitesla (mT) to reverse the direction of a vortex core. The observed switching mechanism, which can be understood within the framework of micromagnetic theory, gives insights into basic magnetization dynamics and their possible application to data storage technologies.

10

Magnetic Vortex Core Reversal by Low-Field Excitations  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnetic Vortex Core Reversal by Low-Field Excitations Print Magnetic Vortex Core Reversal by Low-Field Excitations Print In micrometer-sized magnetic thin films, the magnetization typically adopts an in-plane, circular configuration known as a magnetic vortex. At the vortex core, the magnetization turns sharply out of the plane, pointing either up or down. Magnetic data storage based on this binary phenomenon is an intriguing concept, but it would require the ability to flip the vortex cores on demand. Because these structures are highly stable, very strong magnetic fields of around half a tesla (approximately one-third the field of the strongest permanent magnet) were previously thought to be necessary to accomplish this. At the ALS, a team of researchers from Germany, Belgium, and the U.S. has used time-resolved scanning transmission x-ray microscopy (STXM) to observe vortex motion and demonstrate the feasibility of using weak magnetic fields as low as 1.5 millitesla (mT) to reverse the direction of a vortex core. The observed switching mechanism, which can be understood within the framework of micromagnetic theory, gives insights into basic magnetization dynamics and their possible application to data storage technologies.

11

Magnetic Vortex Core Reversal by Low-Field Excitations  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnetic Vortex Core Reversal by Low-Field Excitations Print Magnetic Vortex Core Reversal by Low-Field Excitations Print In micrometer-sized magnetic thin films, the magnetization typically adopts an in-plane, circular configuration known as a magnetic vortex. At the vortex core, the magnetization turns sharply out of the plane, pointing either up or down. Magnetic data storage based on this binary phenomenon is an intriguing concept, but it would require the ability to flip the vortex cores on demand. Because these structures are highly stable, very strong magnetic fields of around half a tesla (approximately one-third the field of the strongest permanent magnet) were previously thought to be necessary to accomplish this. At the ALS, a team of researchers from Germany, Belgium, and the U.S. has used time-resolved scanning transmission x-ray microscopy (STXM) to observe vortex motion and demonstrate the feasibility of using weak magnetic fields as low as 1.5 millitesla (mT) to reverse the direction of a vortex core. The observed switching mechanism, which can be understood within the framework of micromagnetic theory, gives insights into basic magnetization dynamics and their possible application to data storage technologies.

12

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

13

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

14

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

15

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

16

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

17

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Wednesday, 25 November 2009 00:00 Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

18

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Magnetic thin-film nanostructures can exhibit a magnetic vortex state in which the magnetization vectors lie in the film plane and curl around in a closed loop. At the very center of the vortex, a small, stable core exists where the magnetization points either up or down out of the plane. Three years ago, the discovery of an easy core reversal mechanism at the ALS not only made the possibility of using such systems as magnetic memories much more realistic, it also initiated investigation of the core switching mechanism itself. Now, a Belgian-German-ALS collaboration has used high-resolution, time-resolved, magnetic x-ray microscopy to experimentally reveal the first step of the reversal process: the dynamic deformation of the vortex core. The group also measured a critical vortex velocity above which reversal occurs. Both these observations provide the first experimental support for the postulated reversal mechanism.

19

Observation of coupled vortex gyrations by 70-ps-time and 20-nm-space- resolved full-field magnetic transmission soft x-ray microscopy  

SciTech Connect

We employed time-and space-resolved full-field magnetic transmission soft x-ray microscopy to observe vortex-core gyrations in a pair of dipolar-coupled vortex-state Permalloy (Ni{sub 80}Fe{sub 20}) disks. The 70 ps temporal and 20 nm spatial resolution of the microscope enabled us to simultaneously measure vortex gyrations in both disks and to resolve the phases and amplitudes of both vortex-core positions. We observed their correlation for a specific vortex-state configuration. This work provides a robust and direct method of studying vortex gyrations in dipolar-coupled vortex oscillators.

Jung, Hyunsung; Yu, Young-Sang; Lee, Ki-Suk; Im, Mi-Young; Fischer, Peter; Bocklage, Lars; Vogel, Andreas; Bolte, Markus; Meier, Guido; Kim, Sang-Koog

2010-09-01T23:59:59.000Z

20

Argonne CNM Highlight: Biofunctionalized magnetic-vortex microdiscs for  

NLE Websites -- All DOE Office Websites (Extended Search)

Biofunctionalized magnetic-vortex microdiscs for targeted cancer-cell destruction Biofunctionalized magnetic-vortex microdiscs for targeted cancer-cell destruction Magnetic microdisks Reflection optical microscope image of a dried suspension of the discs prepared via magnetron sputtering and optical lithography. Magnetic spin vortex Model of magnetic-vortex spin distribution in a disc. Users from Argonne's Materials Science Division and University of Chicago's Pritzker School of Medicine, working collaboratively on a user science project with CNM's Nanobio Interfaces Group, have discovered that nanostructured magnetic materials offer exciting avenues for probing cell mechanics, activating mechanosensitive ion channels, and advancing potential cancer therapies. Their new report describes an approach based on interfacing cells with lithographically defined microdiscs (1-micron

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Switching a magnetic vortex by interlayer coupling in epitaxially grown Co/Cu/Py/Cu(001) trilayer disks  

SciTech Connect

Epitaxial Py/Cu/Co/Cu(001) trilayers were patterned into micron sized disks and imaged using element-specific photoemission electron microscopy. By varying the Cu spacer layer thickness, we study how the coupling between the two magnetic layers influences the formation of magnetic vortex states. We find that while the Py and Co disks form magnetic vortex domains when the interlayer coupling is ferromagnetic, the magnetic vortex domains of the Py and Co disks break into anti-parallel aligned multidomains when the interlayer coupling is antiferromagnetic. We explain this result in terms of magnetic flux closure between the Py and Co layers for the antiferromagnetic coupling case.

Wu, J.; Carlton, D.; Oelker, E.; Park, J. S.; Jin, E.; Arenholz, E.; Scholl, A.; Hwang, C.; Bokor, J.; Qiu, Z Q

2010-07-16T23:59:59.000Z

22

Ferroelectric nanostructure having switchable multi-stable vortex states  

DOE Patents (OSTI)

A ferroelectric nanostructure formed as a low dimensional nano-scale ferroelectric material having at least one vortex ring of polarization generating an ordered toroid moment switchable between multi-stable states. A stress-free ferroelectric nanodot under open-circuit-like electrical boundary conditions maintains such a vortex structure for their local dipoles when subject to a transverse inhomogeneous static electric field controlling the direction of the macroscopic toroidal moment. Stress is also capable of controlling the vortex's chirality, because of the electromechanical coupling that exists in ferroelectric nanodots.

Naumov, Ivan I. (Fayetteville, AR); Bellaiche, Laurent M. (Fayetteville, AR); Prosandeev, Sergey A. (Fayetteville, AR); Ponomareva, Inna V. (Fayetteville, AR); Kornev, Igor A. (Fayetteville, AR)

2009-09-22T23:59:59.000Z

23

Method for the detection of a magnetic field utilizing a magnetic vortex  

SciTech Connect

The determination of the strength of an in-plane magnetic field utilizing one or more magnetically-soft, ferromagnetic member, having a shape, size and material whereas a single magnetic vortex is formed at remanence in each ferromagnetic member. The preferred shape is a thin circle, or dot. Multiple ferromagnetic members can also be stacked on-top of each other and separated by a non-magnetic spacer. The resulting sensor is hysteresis free. The sensor's sensitivity, and magnetic saturation characteristics may be easily tuned by simply altering the material, size, shape, or a combination thereof to match the desired sensitivity and saturation characteristics. The sensor is self-resetting at remanence and therefore does not require any pinning techniques.

Novosad, Valentyn (Chicago, IL); Buchanan, Kristen (Batavia, IL)

2010-04-13T23:59:59.000Z

24

Magnetic Vortex Core Reversal by Low-Field Excitations  

NLE Websites -- All DOE Office Websites (Extended Search)

on this binary phenomenon is an intriguing concept, but it would require the ability to flip the vortex cores on demand. Because these structures are highly stable, very strong...

25

Evidence of small-scale magnetic concentrations dragged by vortex motion of solar photospheric plasma  

E-Print Network (OSTI)

Vortex-type motions have been measured by tracking bright points in high-resolution observations of the solar photosphere. These small-scale motions are thought to be determinant in the evolution of magnetic footpoints and their interaction with plasma and therefore likely to play a role in heating the upper solar atmosphere by twisting magnetic flux tubes. We report the observation of magnetic concentrations being dragged towards the center of a convective vortex motion in the solar photosphere from high-resolution ground-based and space-borne data. We describe this event by analyzing a series of images at different solar atmospheric layers. By computing horizontal proper motions, we detect a vortex whose center appears to be the draining point for the magnetic concentrations detected in magnetograms and well-correlated with the locations of bright points seen in G-band and CN images.

Balmaceda, L; Palacios, J; Cabello, I; Domingo, V

2010-01-01T23:59:59.000Z

26

Magnetic Edge States in Graphene  

E-Print Network (OSTI)

Magnetic confinement in graphene has been of recent and growing interest because its potential applications in nanotechnology. In particular, the observation of the so called magnetic edge states in graphene has opened the possibility to deepen into the generation of spin currents and its applications in spintronics. We study the magnetic edge states of quasi-particles arising in graphene monolayers due to an inhomogeneous magnetic field of a magnetic barrier in the formalism of the two-dimensional massless Dirac equation. We also show how the solutions of such states in each of both triangular sublattices of the graphene are related through a supersymmetric transformation in the quantum mechanical sense.

Gabriela Murguia

2010-08-29T23:59:59.000Z

27

Simulations of 2D magnetic electron drift vortex mode turbulence in plasmas  

E-Print Network (OSTI)

Simulations are performed to investigate turbulent properties of nonlinearly interacting two-dimensional (2D) magnetic electron drift vortex (MEDV) modes in a nonuniform unmagnetized plasma. The relevant nonlinear equations governing the dynamics of the MEDV modes are the wave magnetic field and electron temperature perturbations in the presence of the equilibrium density and temperature gradients. The important nonlinearities come from the advection of the electron fluid velocity perturbation and the electron temperature, as well as from the nonlinear electron Lorentz force. Computer simulations of the governing equations for the nonlinear MEDV modes reveal the generation of streamer-like electron flows, such that the corresponding gradients in the direction of the inhomogeneities tend to flatten out. By contrast, the gradients in an orthogonal direction vary rapidly. Consequently, the inertial range energy spectrum in decaying MEDV mode turbulence exhibits a much steeper anisotropic spectral index. The magn...

Shaikh, Dastgeer

2008-01-01T23:59:59.000Z

28

3D-vortex labyrinths in the near field of solid-state microchip laser  

E-Print Network (OSTI)

The spatiotemporal vortex lattices generated in high Fresnel number solid-state microchip lasers are studied in connection with Talbot phenomenon generic to spatially periodic electromagnetic fields. The spatial layout of light field is obtained via dynamical model based on Maxwell-Bloch equations for class-B laser, discrete Fox-Lee map with relaxation of inversion and static model based on superposition of copropagating Gaussian beams. The spatial patterns observed experimentally and obtained numerically are interpreted as nonlinear superposition of vortices with helicoidal phase dislocations. The usage of vortex labyrinths and Talbot lattices as optical dipole traps for neutral atoms is considered for the wavelength of trapping radiation in the range 0.98 $\\div$ 2.79 $\\mu m$. The separable optical trapping potential is mounted as a sum of array of vortex lines and additional parabolic subtrap. The factorization of macroscopic wavefunction have led to analytical solution of Gross-Pitaevski equation for ground state of ensemble of quantum particles trapped in vortex labyrinth and in spatially - periodic array of Gaussian beams.

A. Yu. Okulov

2007-01-21T23:59:59.000Z

29

Persistence of Metastable Vortex Lattice Domains in MgB2 in the Presence of Vortex Motion  

Science Conference Proceedings (OSTI)

Recently, extensive vortex lattice metastability was reported in MgB2 in connection with a second-order rotational phase transition. However, the mechanism responsible for these well-ordered metastable vortex lattice phases is not well understood. Using small-angle neutron scattering, we studied the vortex lattice in MgB2 as it was driven from a metastable to the ground state through a series of small changes in the applied magnetic field. Our results show that metastable vortex lattice domains persist in the presence of substantial vortex motion and directly demonstrate that the metastability is not due to vortex pinning. Instead, we propose that it is due to the jamming of counterrotated vortex lattice domains which prevents a rotation to the ground state orientation.

Rastovski, Catherine [University of Notre Dame, IN; Schlesinger, Kimberly [University of Notre Dame, IN; Gannon, William J [Northwestern University, Evanston; Dewhurst, Charles [Institut Laue-Langevin (ILL); Debeer-Schmitt, Lisa M [ORNL; Zhigadlo, Nikolai [ETH Zurich, Switzerland; Karpinski, Janusz [ETH Zurich, Switzerland; Eskildsen, Morten [University of Notre Dame, IN

2013-01-01T23:59:59.000Z

30

Magnetic Blockade Mechanism for Quantum Nucleation of Superconducting Vortex-Antivortex Pairs in Zero External Magnetic Field  

E-Print Network (OSTI)

We propose a magnetic dual of the Coulomb blockade effect for quantum nucleation of flux vortex pairs in high-Tc superconducting (HTS) films and grain boundaries in zero applied field. The magnetic blockade instability occurs at {\\theta} = {\\pi}, where {\\theta} is the "vacuum" or theta angle. The {\\theta} term has recently been discussed in the context of several other systems, including charge and spin density waves, topological insulators, the quantum Hall effect, and spontaneous CP violation. Our model predicts a sharp pair creation threshold current at {\\theta} = {\\pi}, analogous to the Coulomb blockade voltage of a tunnel junction, and explains the observed thickness dependence of critical currents in HTS coated conductors. We use the Schr\\"odinger equation to compute the evolving macrostate amplitudes, coupled by a generalized tunneling matrix element. The simulations yield excellent quantitative agreement with measured voltage-current characteristics of bi-crystal and other HTS grain boundary junctions. The model also predicts non-sinusoidal behavior in the voltage oscillations resulting from time-correlated vortex tunneling.

J. H. Miller Jr.; A. I. Wijesinghe

2011-10-12T23:59:59.000Z

31

Probing the spin polarization of current by soft x-ray imaging of current-induced magnetic vortex dynamics  

SciTech Connect

Time-resolved soft X-ray transmission microscopy is applied to image the current-induced resonant dynamics of the magnetic vortex core realized in a micron-sized Permalloy disk. The high spatial resolution better than 25 nm enables us to observe the resonant motion of the vortex core. The result also provides the spin polarization of the current to be 0.67 {+-} 0.16 for Permalloy by fitting the experimental results with an analytical model in the framework of the spin-transfer torque.

Kasai, Shinya; Fischer, Peter; Im, Mi-Young; Yamada, Keisuke; Nakatani, Yoshinobu; Kobayashi, Kensuke; Kohno, Hiroshi; Ono, Teruo

2008-12-09T23:59:59.000Z

32

Reply to "Comment on 'Vortex-assisted photon counts and their magnetic field dependence in single-photon superconducting detectors'"  

SciTech Connect

The vortex crossing rate in thin current-biased superconducting strips, calculated within the London approach employing the concept of a vortex as a particle, is very sensitive to the cutoff at the vortex core size. To account properly for the vortex core, one needs to use microscopic theory.

Bulaevskii, L.N.; Graf, Matthias; Kogan, Vladimir G.

2012-07-16T23:59:59.000Z

33

X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation  

NLE Websites -- All DOE Office Websites (Extended Search)

new materials with new switching mechanisms. Uncovered by basic research into the fundamentals of magnetism, one such candidate consists of miniscule magnetic vortices like...

34

Vortex lattices in layered superconductors  

Science Conference Proceedings (OSTI)

We study vortex lattices in a superconductor--normal-metal superlattice in a parallel magnetic field. Distorted lattices, resulting from the shear deformations along the layers, are found to be unstable. Under field variation, nonequilibrium configurations undergo an infinite sequence of continuous transitions, typical for soft lattices. The equilibrium vortex arrangement is always a lattice of isocell triangles, without shear.

Prokic, V. (Department of Physics, University of Belgrade, P.O. Box 368, 11001 Belgrade (Yugoslavia)); Davidovic, D. (Department of Physics and Astronomy, The Johns Hopkins University, Bloomberg Center, Baltimore, Maryland 21218 (United States) Institute of Physics, P.O. Box 57, 11001 Belgrade (Yugoslavia)); Dobrosavljevic-Grujic, L. (Institute of Physics, P.O. Box 57, 11001 Belgrade (Yugoslavia))

1995-03-01T23:59:59.000Z

35

Bound states in a strong magnetic field  

SciTech Connect

We expect a strong magnetic field to be produced in the perpendicular direction to the reaction plane, in a noncentral heavy-ion collision . The strength of the magnetic field is estimated to be eB{approx}m{sup 2}{sub {pi}}{approx} 0.02 GeV{sup 2} at the RHIC and eB{approx} 15m{sup 2}{sub {pi}}{approx} 0.3 GeV{sup 2} at the LHC. We investigate the effects of the magnetic field on B{sup 0} and D{sup 0} mesons, focusing on the changes of the energy levels and of the mass of the bound states.

Machado, C. S.; Navarra, F. S.; Noronha, J.; Oliveira, E. G. [Instituto de Fisica, Universidade de Sao Paulo Rua do Matao, Travessa R, 187, 05508-090 Sao Paulo, SP (Brazil); Ferreira Filho, L. G. [Departamento de Matematica e Computacao, Faculdade de Tecnologia, Universidade do Estado do Rio de Janeiro Rodovia Presidente Dutra, km 298, Polo Industrial, CEP 27537-000, Resende, RJ (Brazil)

2013-03-25T23:59:59.000Z

36

Vortex methods and vortex statistics  

SciTech Connect

Vortex methods originated from the observation that in incompressible, inviscid, isentropic flow vorticity (or, more accurately, circulation) is a conserved quantity, as can be readily deduced from the absence of tangential stresses. Thus if the vorticity is known at time t = 0, one can deduce the flow at a later time by simply following it around. In this narrow context, a vortex method is a numerical method that makes use of this observation. Even more generally, the analysis of vortex methods leads, to problems that are closely related to problems in quantum physics and field theory, as well as in harmonic analysis. A broad enough definition of vortex methods ends up by encompassing much of science. Even the purely computational aspects of vortex methods encompass a range of ideas for which vorticity may not be the best unifying theme. The author restricts himself in these lectures to a special class of numerical vortex methods, those that are based on a Lagrangian transport of vorticity in hydrodynamics by smoothed particles (``blobs``) and those whose understanding contributes to the understanding of blob methods. Vortex methods for inviscid flow lead to systems of ordinary differential equations that can be readily clothed in Hamiltonian form, both in three and two space dimensions, and they can preserve exactly a number of invariants of the Euler equations, including topological invariants. Their viscous versions resemble Langevin equations. As a result, they provide a very useful cartoon of statistical hydrodynamics, i.e., of turbulence, one that can to some extent be analyzed analytically and more importantly, explored numerically, with important implications also for superfluids, superconductors, and even polymers. In the authors view, vortex ``blob`` methods provide the most promising path to the understanding of these phenomena.

Chorin, A.J.

1993-05-01T23:59:59.000Z

37

An Intense Small-Scale Wintertime Vortex in the Midwest United States  

Science Conference Proceedings (OSTI)

An intense small-scale low pressure system that moved across portions of the midwest United States is examined. The system produced a continuous band of significant snowfall, typically only 50 km wide but extending over 1500 km in length. The ...

William A. Gallus Jr.; James F. Bresch

1997-11-01T23:59:59.000Z

38

Spontaneous Symmetry-Breaking and the Vortex Lattice ...  

Science Conference Proceedings (OSTI)

... The magnetic vortex lattice of Type-II superconductors, as a quasi ... morphology in single-crystals of pure niobium, a 'conventional' superconductor. ...

39

Equilibrium magnetic states in individual hemispherical permalloy caps  

Science Conference Proceedings (OSTI)

The magnetization distributions in individual soft magnetic permalloy caps on non-magnetic spherical particles with sizes ranging from 50 to 800 nm are investigated. We experimentally visualize the magnetic structures at the resolution limit of the x-ray magnetic circular dichroism photoelectron emission microscopy (XMCD-PEEM). By analyzing the so-called tail contrast in XMCD-PEEM, the spatial resolution is significantly enhanced, which allowed us to explore magnetic vortices and their displacement on curved surfaces. Furthermore, cap nanostructures are modeled as extruded hemispheres to determine theoretically the phase diagram of equilibrium magnetic states. The calculated phase diagram agrees well with the experimental observations.

Streubel, Robert; Schmidt, Oliver G. [Institute for Integrative Nanosciences, IFW Dresden, 01069 Dresden (Germany); Material Systems for Nanoelectronics, Chemnitz University of Technology, 09107 Chemnitz (Germany); Kravchuk, Volodymyr P.; Gaididei, Yuri [Bogolyubov Institute for Theoretical Physics, 03143 Kiev (Ukraine); Sheka, Denis D. [Radiophysics Faculty, Taras Shevchenko National University of Kiev, 01601 Kiev (Ukraine); Makarov, Denys [Institute for Integrative Nanosciences, IFW Dresden, 01069 Dresden (Germany); Kronast, Florian [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, 12489 Berlin (Germany)

2012-09-24T23:59:59.000Z

40

Ionizationexcitation magnetic sublevel cross sections states following fast electron  

E-Print Network (OSTI)

Center for Astrophysics, Cambridge, MA 02138, USA Abstract The first experimental magnetic substate S ground state to the final ionic state Heþ (2p) 2 P0 (also noted as HeII(2p) 2 P0 ) in e� þ He single that these absolute total cross sections do not provide direct information about the magnetic substate populations

Godunov, Alexander L.

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Statistical Behavior of Formation Process of Magnetic Vortex State in Ni80Fe20 Nanodisks  

E-Print Network (OSTI)

This work was supported by the Director, Office of Science,Office of Basic Energy Sciences, Materials Sciences and

Im, Mi-Young

2011-01-01T23:59:59.000Z

42

Vortex Energy | Open Energy Information  

Open Energy Info (EERE)

by expanding it. Vortex Energy is a company located in Germany . References "Vortex Energy" Retrieved from "http:en.openei.orgwindex.php?titleVortexEnergy&oldid352892...

43

Vortex ice in nanostructured superconductors  

SciTech Connect

We demonstrate using numerical simulations of nanostructured superconductors that it is possible to realize vortex ice states that are analogous to square and kagome ice. The system can be brought into a state that obeys either global or local ice rules by applying an external current according to an annealing protocol. We explore the breakdown of the ice rules due to disorder in the nanostructure array and show that in square ice, topological defects appear along grain boundaries, while in kagome ice, individual defects appear. We argue that the vortex system offers significant advantages over other artificial ice systems.

Reichhardt, Charles [Los Alamos National Laboratory; Reichhardt, Cynthia J [Los Alamos National Laboratory; Libal, Andras J [Los Alamos National Laboratory

2008-01-01T23:59:59.000Z

44

Ground State Magnetic Moments of Mirror Nuclei Studied at NSCL  

E-Print Network (OSTI)

Progress in the measurement of the ground state magnetic moments of mirror nuclei at NSCL is presented. The systematic trend of the spin expectation value $$ and the linear behavior of $\\gamma_p$ versus $\\gamma_n$, both extracted from the magnetic moments of mirror partners, are updated to include all available data.

P. F. Mantica; K. Minamisono

2009-01-22T23:59:59.000Z

45

On the energy of bound states for magnetic Schrödinger operators  

E-Print Network (OSTI)

We provide a leading order semiclassical asymptotics of the energy of bound states for magnetic Neumann Schr\\"odinger operators in two dimensional (exterior) domains with smooth boundaries. The asymptotics is valid all the way up to the bottom of the essential spectrum. When the spectral parameter is varied near the value where bound states become allowed in the interior of the domain, we show that the energy has a boundary and a bulk component. The estimates rely on coherent states, in particular on the construction of `boundary coherent states', and magnetic Lieb-Thirring estimates.

S. Fournais; A. Kachmar

2008-10-01T23:59:59.000Z

46

Vortex Breakdown in Atmospheric Columnar Vortices  

Science Conference Proceedings (OSTI)

Vortex breakdown occurs in tornadoes and waterspouts. This phenomenon may give information on the state and future behavior of those whirlwinds. Because of the rarity of recorded events, archival sources are consulted for qualitative descriptions ...

H. J. Lugt

1989-12-01T23:59:59.000Z

47

Understanding and controlling complex states arising from magnetic frustration  

SciTech Connect

Much of our national security relies on capabilities made possible by magnetism, in particular the ability to compute and store huge bodies of information as well as to move things and sense the world. Most of these technologies exploit ferromagnetism, i.e. the global parallel alignment of magnetic spins as seen in a bar magnet. Recent advances in computing technologies, such as spintronics and MRAM, take advantage of antiferromagnetism where the magnetic spins alternate from one to the next. In certain crystal structures, however, the spins take on even more complex arrangements. These are often created by frustration, where the interactions between spins cannot be satisfied locally or globally within the material resulting in complex and often non-coplanar spin textures. Frustration also leads to the close proximity of many different magnetic states, which can be selected by small perturbations in parameters like magnetic fields, temperature and pressure. It is this tunability that makes frustrated systems fundamentally interesting and highly desirable for applications. We move beyond frustration in insulators to itinerant systems where the interaction between mobile electrons and the non-coplanar magnetic states lead to quantum magneto-electric amplification. Here a small external field is amplified by many orders of magnitude by non-coplanar frustrated states. This greatly enhances their sensitivity and opens broader fields for applications. Our objective is to pioneer a new direction for condensed matter science at the Laboratory as well as for international community by discovering, understanding and controlling states that emerge from the coupling of itinerant charges to frustrated spin textures.

Zapf, Vivien [Los Alamos National Laboratory

2012-06-01T23:59:59.000Z

48

Edge states induced by Iwatsuka Hamiltonians with positive magnetic fields  

E-Print Network (OSTI)

We study purely magnetic Schr\\"odinger operators in two-dimensions $(x,y)$ with magnetic fields $b(x)$ that depend only on the $x$-coordinate. The magnetic field $b(x)$ is assumed to be bounded, there are constants $0 \\epsilon$. The case of a jump in the magnetic field at $x=0$ corresponding to $\\epsilon=0$ is also studied. We prove that the magnetic field creates an effective barrier near $x=0$ that causes edge currents to flow along it consistent with the classical interpretation. We prove lower bounds on edge currents carried by states with energy localized inside the energy bands of the Hamiltonian. We prove that these edge current-carrying states are well-localized in $x$ to a region of size $b_-^{-1/2}$, also consistent with the classical interpretation. We demonstrate that the edge currents are stable with respect to various magnetic and electric perturbations. For a family of perturbations compactly supported in the $y$-direction, we prove that the time asymptotic current exists and satisfies the same lower bound.

Peter D. Hislop; Eric Soccorsi

2013-07-23T23:59:59.000Z

49

Bounds on the entanglability of thermal states in liquid-state nuclear magnetic resonance  

E-Print Network (OSTI)

Theorists have recently shown that the states used in current nuclear magnetic resonance (NMIR) quantum computing experiments are not entangled. Yet it is widely believed that entanglement is a necessary resource in the ...

Yu, Terri M. (Terri Mak), 1981-

2003-01-01T23:59:59.000Z

50

Vortex Dynamics in NanoScale Materials  

NLE Websites -- All DOE Office Websites (Extended Search)

Into the Vortex: Dynamics in Nanoscale Materials Into the Vortex: Dynamics in Nanoscale Materials Micron and nanosized magnets are of great interest for their potential applications in new electronic devices, such as magnetic random access memories. As the size of magnets is reduced to a 1-micron scale and below, the boundaries (surfaces, perimeters, etc) of the objects begin to profoundly influence both the static and dynamic behavior of the materials. Researchers from Argonne's Materials Science Division (MSD), Center for Nanoscale Materials (CNM), and Advanced Photon Source (APS) have recently examined the dynamics of 3- to 7-micron-diameter NiFe alloy disks with a combination of theoretical calculations and a new time-resolved magnetic imaging technique using synchrotron-based x-ray photoemission electron

51

Improved vortex reactor system  

DOE Patents (OSTI)

An improved vortex reactor system for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor.

Diebold, James P. (Lakewood, CO); Scahill, John W. (Evergreen, CO)

1995-01-01T23:59:59.000Z

52

Scaling analysis and application: Phase diagram of magnetic nanorings and elliptical nanoparticles  

Science Conference Proceedings (OSTI)

The magnetic properties of single-domain nanoparticles with different geometric shapes, crystalline anisotropies, and lattice structures are investigated. A recently proposed scaling approach is shown to be universal and in agreement with dimensional analysis coupled with the assumption of incomplete self-similarity. It is used to obtain phase diagrams of magnetic nanoparticles featuring three competing configurations: in-plane ferromagnetism, out-of-plane ferromagnetism, and vortex formation. The influence of the vortex core on the scaling behavior and phase diagram is analyzed. Three-dimensional phase diagrams are obtained for cylindrical nanorings depending on their height and outer and inner radii. The triple points in these phase diagrams are shown to be in a linear relationship with the inner radius of the ring. Elliptically shaped magnetic nanoparticles are also studied. A new parametrization for double vortex configurations is proposed, and regions in the phase diagram where the double vortex is a stable ground state are identified.

Zhang Wen; Singh, Rohit; Bray-Ali, Noah; Haas, Stephan [Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089 (United States)

2008-04-01T23:59:59.000Z

53

Magnetic Charge of the Stark States of Hydrogen Atoms  

E-Print Network (OSTI)

It is conjectured that Stark states of excited hydrogen atom posses magnetic charge for which the quantum mechanical operator is $${\\cal G}_{op} = {e\\over \\hbar} (\\vec\\sigma\\cdot\\vec A)$$ where $\\vec A$ is the Runge-Lenz vector. The expectation value $g$ of this operator for Stark states is found to be $$ g = e(n_1-n_2)$$ which obeys a Dirac-Saha type quantization formula $${eg\\over c} = (n_1-n_2)\\alpha$$ where $\\alpha$ is the fine structure constant and $n_1$ and $n_2$ are parabolic quantum numbers. An experimental arrangement is outlined to test this conjecture.

T. Pradhan

2008-09-28T23:59:59.000Z

54

An Investigation of a Three-Dimensional Asymmetric Vortex  

Science Conference Proceedings (OSTI)

A three-dimensional numerical simulation is presented for the asymmetric vortex motion which occurs in a Ward-type vortex chamber. The initial state is taken to be one of axisymmetric irrotational flow where the flow enters through the sides at ...

Richard Rotunno

1984-01-01T23:59:59.000Z

55

Electron trapping by a current vortex F. Bentosela, a;b P. Exner, c;d and V.A. Zagrebnov a;b  

E-Print Network (OSTI)

with the magnetic field due to an electric current forming a localized rotationally symmetric vortex. We show simpler example involves a Pauli electron interacting with a flux tube modelling a vortex magnetic field field Ansatz. To illustrate this point we analyze in this letter the situation where the vortex current

56

Anomalous electron trapping by magnetic flux tubes and electric current vortices  

E-Print Network (OSTI)

Anomalous electron trapping by magnetic flux tubes and electric current vortices F. Bentosela, a current vortex in the plane. In this case the flux is zero; there is a pair of bound states for a weak with a nonhomogeneous magnetic field B , and investigate the corresponding Pauli Hamiltonian. We prove a lower bound

57

VORTEX.PDF  

NLE Websites -- All DOE Office Websites (Extended Search)

vortex generator. Figure 5. The fan in its plenum-a two-speed stove fan mounted in a plywood box. It provides a vacuum at the top of the generator. The ruler is six inches long....

58

Improved vortex reactor system  

DOE Patents (OSTI)

An improved vortex reactor system is described for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor. 12 figs.

Diebold, J.P.; Scahill, J.W.

1995-05-09T23:59:59.000Z

59

Entanglement of a Quantum Optical Elliptic Vortex  

E-Print Network (OSTI)

We calculate the entanglement of a generalized elliptical vortex formed by quantized radiation field, using Wigner quasiprobability distribution function for such states. We find a critical squeezing parameter above which the entanglement is less for higher vorticity, which is counter intuitive.

Abir Bandyopadhyay; Shashi Prabhakar; Ravindra Pratap Singh

2010-10-19T23:59:59.000Z

60

Entanglement of Quantum Optical Elliptic Vortex  

E-Print Network (OSTI)

We calculate the entanglement of a generalized elliptical vortex formed by quantized radiation field, using Wigner quasiprobability distribution function for such states. We find a critical squeezing parameter above which the entanglement is less for higher vorticity, which is counter intuitive.

Bandyopadhyay, Abir; Singh, Ravindra Pratap

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Vortex Hydro Energy LLC | Open Energy Information  

Open Energy Info (EERE)

Hydro Energy LLC Hydro Energy LLC Jump to: navigation, search Name Vortex Hydro Energy LLC Address 4870 West Clark Rd Suite 108 Place Ypsilanti Zip 48197 Sector Marine and Hydrokinetic Phone number 734.971.4020 Website http://www.vortexhydroenergy.c Region United States LinkedIn Connections CrunchBase Profile No CrunchBase profile. Create one now! This company is listed in the Marine and Hydrokinetic Technology Database. This company is involved in the following MHK Projects: Marine Hydrodynamics Laboratory at the University of Michigan This company is involved in the following MHK Technologies: Vortex Induced Vibrations Aquatic Clean Energy VIVACE This article is a stub. You can help OpenEI by expanding it. Retrieved from "http://en.openei.org/w/index.php?title=Vortex_Hydro_Energy_LLC&oldid=678497

62

Structure of quantum vortex tangle in He-4 counterflow turbulence  

E-Print Network (OSTI)

The main goal of this paper is to present a comprehensive characterization of well developed vortex tangles in a turbulent counterflow in quantum fluids (with a laminar normal fluid component). We analyze extensive numerical simulations using the vortex filament method, solving the full Biot-Savart equations for the vortex dynamics in a wide range of temperatures and counter-flow velocities. In addition to a detailed analysis of traditional characteristics such as vortex line density, anisotropic and curvature parameters of the vortex tangle, we stress other dynamical and statistical characteristics which are either much less studied or even unstudied. The latter include reconnection rates, mean mutual friction forces, drift velocities and the probability distribution functions of various tangle parameters: the loop length, the line curvature, the mean curvature of loops with a given length, etc. During these studies we compare the three main reconnection procedures which are widely used in the literature, and identify which properties are strongly affected by the choice of the reconnection criteria and which of them are practically insensitive to the reconnection procedure. The conclusion is that the vortex filament method in the framework of the Biot-Savart equation sufficiently robust and well suited for the description of the steady state vortex tangle in a quantum counterflow. The Local-Induction Approximation to this equation may be successfully used to analytically establish relationships between mean characteristics of the stochastic vortex tangle.

Luiza Kondaurova; Victor L'vov; Anna Pomyalov; Itamar Procaccia

2013-06-26T23:59:59.000Z

63

Circular Rydberg states of atomic hydrogen in an arbitrary magnetic field  

E-Print Network (OSTI)

We report a theoretical scheme using a B-spline basis set to improve the poor computational accuracy of circular Rydberg states of hydrogen atoms in the intermediate magnetic field. This scheme can produce high accuracy energy levels and valid for an arbitrary magnetic field. Energy levels of hydrogen are presented for circular Rydberg states with azimuthal quantum numbers $|m|$ = 10 - 70 as a function of magnetic field strengths ranging from zero to 2.35 $\\times$ 10$^9$ T. The variation of spatial distributions of electron probability densities with magnetic field strengths is discussed and competition between Coulomb and magnetic interactions is illustrated.

Zhao, L B; Du, M L

2011-01-01T23:59:59.000Z

64

Impact of a vortex ring on a density interface using a regularized inviscid vortex sheet method  

Science Conference Proceedings (OSTI)

A new, fully three-dimensional, vortex-in-cell method designed to follow the unsteady motion of inviscid vortex sheets with or without small (Boussinesq) density discontinuities is presented. As is common in front-tracking methods, the vortex sheet is ... Keywords: Density discontinuity, Stratified flow, Vortex methods, Vortex sheet dynamics, Vortex-in-cell

Mark J. Stock; Werner J. A. Dahm; Grétar Tryggvason

2008-11-01T23:59:59.000Z

65

Identification of vortexes obstructing the dynamo mechanism in laboratory experiments  

E-Print Network (OSTI)

The magnetohydrodynamic dynamo effect explains the generation of self-sustained magnetic fields in electrically conducting flows, especially in geo- and astrophysical environments. Yet the details of this mechanism are still unknown, e.g., how and to which extent the geometry, the fluid topology, the forcing mechanism and the turbulence can have a negative effect on this process. We report on numerical simulations carried out in spherical geometry, analyzing the predicted velocity flow with the so-called Singular Value Decomposition, a powerful technique that allows us to precisely identify vortexes in the flow which would be difficult to characterize with conventional spectral methods. We then quantify the contribution of these vortexes to the growth rate of the magnetic energy in the system. We identify an axisymmetric vortex, whose rotational direction changes periodically in time, and whose dynamics are decoupled from those of the large scale background flow, is detrimental for the dynamo effect. A compar...

Limone, Angelo; Forest, Cary B; Jenko, Frank

2013-01-01T23:59:59.000Z

66

Perfectly elastic collisions as origin of quantum states of superconductivity and magnetic order  

E-Print Network (OSTI)

One of the most interesting properties of solid materials is the ability to form different collective quantum states, such as superconductivity and magnetic order. This paper presents a model of perfectly elastic collisions (p.e.c.) as the universal origin of these collective quantum states. The superb agreement between calculated values and experimental data for critical temperatures, moreover, the explanation of the isotope effect in superconductivity and magnetic order confirms that this model successfully describes these two quantum states.

Mushkolaj Shpend

2008-10-23T23:59:59.000Z

67

Free Magnetic Energy in Solar Active Regions above the Minimum-Energy Relaxed State  

E-Print Network (OSTI)

To understand the physics of solar flares, including the local reorganisation of the magnetic field and the acceleration of energetic particles, we have first to estimate the free magnetic energy available for such phenomena, which can be converted into kinetic and thermal energy. The free magnetic energy is the excess energy of a magnetic configuration compared to the minimum-energy state, which is a linear force-free field if the magnetic helicity of the configuration is conserved. We investigate the values of the free magnetic energy estimated from either the excess energy in extrapolated fields or the magnetic virial theorem. For four different active regions, we have reconstructed the nonlinear force-free field and the linear force-free field corresponding to the minimum-energy state. The free magnetic energies are then computed. From the energy budget and the observed magnetic activity in the active region, we conclude that the free energy above the minimum-energy state gives a better estimate and more insights into the flare process than the free energy above the potential field state.

S. Regnier; E. R. Priest

2008-05-12T23:59:59.000Z

68

Evolution of Magnetic Oxygen States in Sr-Doped LaCoO3  

SciTech Connect

Magnetism in La1-xSrxCoO3 as a function of doping is investigated with x-ray absorption spectroscopy and x-ray magnetic circular dicrhoism at the O K edge, and corresponding first principles electronic structure calculations. For small x, the spectra are consistent with the formation of ferromagnetic clusters occurring within a nonmagnetic insulating matrix. Sr-induced, magnetic O-hole states form just above EF and grow with increasing Sr doping. Density functional calculations for x=0 yield a nonmagnetic ground state with the observed rhombohedral distortion and indicates that doping introduces holes at the Fermi level in magnetic states with significant O 2p and Co t2g character for the undistorted pseudocubic structure. Supercell calculations show stronger magnetism on oxygen atoms having more Sr neighbors.

Medling, S.; Lee, Yuen; Zheng, H.; Mitchell, J.F.; Freeland, J.W.; Harmon, Bruce N.; Bridges, F.

2012-10-12T23:59:59.000Z

69

Contribution of Eu 4f states to the magnetic anisotropy of EuO  

Science Conference Proceedings (OSTI)

Anisotropic x-ray magnetic linear dichroism (AXMLD) provides a novel element-, site-, shell-, and symmetry-selective techniques to study the magnetic anisotropy induced by a crystalline electric field. The weak Eu2+ M4,5 AXMLD observed in EuO(001) indicates that the Eu 4f states are not rotationally invariant and hence contribute weakly to the magnetic anisotropy of EuO. The results are contrasted with those obtained for 3d transition metal oxides.

Arenholz, E.; Schmehl, A.; Schlom, D.G.; van der Laan, G.

2008-09-11T23:59:59.000Z

70

Free Magnetic Energy in Solar Active Regions above the Minimum-Energy Relaxed State  

E-Print Network (OSTI)

To understand the physics of solar flares, including the local reorganisation of the magnetic field and the acceleration of energetic particles, we have first to estimate the free magnetic energy available for such phenomena, which can be converted into kinetic and thermal energy. The free magnetic energy is the excess energy of a magnetic configuration compared to the minimum-energy state, which is a linear force-free field if the magnetic helicity of the configuration is conserved. We investigate the values of the free magnetic energy estimated from either the excess energy in extrapolated fields or the magnetic virial theorem. For four different active regions, we have reconstructed the nonlinear force-free field and the linear force-free field corresponding to the minimum-energy state. The free magnetic energies are then computed. From the energy budget and the observed magnetic activity in the active region, we conclude that the free energy above the minimum-energy state gives a better estimate and more ...

Régnier, S

2008-01-01T23:59:59.000Z

71

Variable residence time vortex combustor  

DOE Patents (OSTI)

A variable residence time vortex combustor including a primary combustion chamber for containing a combustion vortex, and a plurality of louvres peripherally disposed about the primary combustion chamber and longitudinally distributed along its primary axis. The louvres are inclined to impel air about the primary combustion chamber to cool its interior surfaces and to impel air inwardly to assist in driving the combustion vortex in a first rotational direction and to feed combustion in the primary combustion chamber. The vortex combustor also includes a second combustion chamber having a secondary zone and a narrowed waist region in the primary combustion chamber interconnecting the output of the primary combustion chamber with the secondary zone for passing only lower density particles and trapping higher density particles in the combustion vortex in the primary combustion chamber for substantial combustion.

Melconian, Jerry O. (76 Beaver Rd., Reading, MA 01867)

1987-01-01T23:59:59.000Z

72

Asymptotics of the ground state energy of heavy molecules in self-generated magnetic field  

E-Print Network (OSTI)

We consider asymptotics of the ground state energy of heavy atoms and molecules in the self-generatedl magnetic field and derive it including Scott, and in some cases even Schwinger and Dirac corrections (if magnetic field is not too strong). We also consider related topics: an excessive negative charge, ionization energy and excessive positive charge when atoms can still bind into molecules.

Victor Ivrii

2013-03-19T23:59:59.000Z

73

Effect of point-like disorder on the vortex phase diagram in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8-{delta}} in oblique field.  

Science Conference Proceedings (OSTI)

The phase diagram of vortex matter in the layered superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8-{delta}} exposed to a magnetic field oblique to the crystalline c-axis contains two first order transition (FOT) lines. The first, H{sub FOT}{sup m}, separates the vortex solid from the vortex liquid, the second, H{sub FOT}{sup ct}, separates the combined lattice state in the vortex solid from a tilted lattice state. The angular dependence of H{sub FOT}{sup m} in the tilted lattice region follows the anisotropic Ginzburg-Landau model, allowing for the determination of the anisotropy factor {gamma}{sub eff} and the contribution of magnetic coupling to the mutual interaction of 'pancake' vortices in the crossed lattice limit. The later parameter is directly related to the in-plane penetration depth {lambda}{sub ab}. We investigate the evolution of the phase diagram of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8-{delta}} in oblique fields with point-like disorder, introduced by irradiation with 2.3 MeV electrons. Apart from the depression of T{sub c}, point-like disorder induces an increase of {gamma}{sub eff} and a depression of the superfluid density.

Konczykowski, M.; van der Beek, C. J.; Mosser, V.; Koshelev, A. E.; Li, M.; Kes, P. H. (Materials Science Division); (Ecole Polytechnique); (ITRON); (Leiden Univ.)

2010-12-01T23:59:59.000Z

74

Method and apparatus for steady-state magnetic measurement of poloidal magnetic field near a tokamak plasma  

DOE Patents (OSTI)

A method and apparatus for the steady-state measurement of poloidal magnetic field near a tokamak plasma, where the tokamak is configured with respect to a cylindrical coordinate system having z, phi (toroidal), and r axes. The method is based on combining the two magnetic field principles of induction and torque. The apparatus includes a rotor assembly having a pair of inductive magnetic field pickup coils which are concentrically mounted, orthogonally oriented in the r and z directions, and coupled to remotely located electronics which include electronic integrators for determining magnetic field changes. The rotor assembly includes an axle oriented in the toroidal direction, with the axle mounted on pivot support brackets which in turn are mounted on a baseplate. First and second springs are located between the baseplate and the rotor assembly restricting rotation of the rotor assembly about its axle, the second spring providing a constant tensile preload in the first spring. A strain gauge is mounted on the first spring, and electronic means to continually monitor strain gauge resistance variations is provided. Electronic means for providing a known current pulse waveform to be periodically injected into each coil to create a time-varying torque on the rotor assembly in the toroidal direction causes mechanical strain variations proportional to the torque in the mounting means and springs so that strain gauge measurement of the variation provides periodic magnetic field measurements independent of the magnetic field measured by the electronic integrators.

Woolley, R.D.

1996-12-31T23:59:59.000Z

75

Method and apparatus for steady-state magnetic measurement of poloidal magnetic field near a tokamak plasma  

DOE Patents (OSTI)

A method and apparatus for the steady-state measurement of poloidal magnetic field near a tokamak plasma, where the tokamak is configured with respect to a cylindrical coordinate system having z, phi (toroidal), and r axes. The method is based on combining the two magnetic field principles of induction and torque. The apparatus includes a rotor assembly having a pair of inductive magnetic field pickup coils which are concentrically mounted, orthogonally oriented in the r and z directions, and coupled to remotely located electronics which include electronic integrators for determining magnetic field changes. The rotor assembly includes an axle oriented in the toroidal direction, with the axle mounted on pivot support brackets which in turn are mounted on a baseplate. First and second springs are located between the baseplate and the rotor assembly restricting rotation of the rotor assembly about its axle, the second spring providing a constant tensile preload in the first spring. A strain gauge is mounted on the first spring, and electronic means to continually monitor strain gauge resistance variations is provided. Electronic means for providing a known current pulse waveform to be periodically injected into each coil to create a time-varying torque on the rotor assembly in the toroidal direction causes mechanical strain variations proportional to the torque in the mounting means and springs so that strain gauge measurement of the variation provides periodic magnetic field measurements independent of the magnetic field measured by the electronic integrators.

Woolley, Robert D. (Hillsborough, NJ)

1998-01-01T23:59:59.000Z

76

Vortex–Vortex Interactions in the Winter Stratosphere  

Science Conference Proceedings (OSTI)

This paper examines the interaction of oppositely signed vortices in the compressible (non-Boussinesq) quasigeostrophic system, with a view to understanding vortex interactions in the polar winter stratosphere. A series of simplifying ...

R. K. Scott; D. G. Dritschel

2006-02-01T23:59:59.000Z

77

Wigner function and entanglement of generalized quantum optical vortex  

E-Print Network (OSTI)

We calculate the Wigner quasiprobability distribution function of the quantum elliptical vortex (QEV), produced by coupling squeezed coherent states of two modes . The coupling between the two modes is performed by using beam splitter (BS) or a dual channel directional coupler (DCDC). The quantum interference due to the coupling between the two modes promises the generation of controlled entanglement for quantum computation and quantum tomography. We calculate the entanglement of such generalized elliptical vortex formed by quantized radiation field (QEV), using Wigner quasiprobability distribution function for such states. We find a critical squeezing parameter above which the entanglement is less for higher vorticity, which is counter intuitive.

Bandyopadhyay, Abir; Singh, R P

2011-01-01T23:59:59.000Z

78

Solving Quantum Ground-State Problems with Nuclear Magnetic Resonance  

E-Print Network (OSTI)

Quantum ground-state problems are computationally hard problems; for general many-body Hamiltonians, there is no classical or quantum algorithm known to be able to solve them efficiently. Nevertheless, if a trial wavefunction approximating the ground state is available, as often happens for many problems in physics and chemistry, a quantum computer could employ this trial wavefunction to project the ground state by means of the phase estimation algorithm (PEA). We performed an experimental realization of this idea by implementing a variational-wavefunction approach to solve the ground-state problem of the Heisenberg spin model with an NMR quantum simulator. Our iterative phase estimation procedure yields a high accuracy for the eigenenergies (to the 10^-5 decimal digit). The ground-state fidelity was distilled to be more than 80%, and the singlet-to-triplet switching near the critical field is reliably captured. This result shows that quantum simulators can better leverage classical trial wavefunctions than c...

Li, Zhaokai; Chen, Hongwei; Lu, Dawei; Whitfield, James D; Peng, Xinhua; Aspuru-Guzik, Alán; Du, Jiangfeng

2011-01-01T23:59:59.000Z

79

Heisenberg-limited measurement of magnetic-field gradient with multipartite entangled states  

E-Print Network (OSTI)

We propose a method to detect the magnetic-field gradient using an atomic spin chain. We consider to use W-states, which are a specific class of multipartite entangled states, for precision measurement. The magnetic-field gradient can be determined by measuring the coherence of the state. We find that the Heisenberg-limited measurement can be obtained even using imperfect W-states and in the presence of various types of noises, respectively. We discuss the implementations of the schemes with trapped ions and ultracold atoms in optical lattices. Our proposal can be realized by using an order of several tens of trapped ions with current technology. This robust method may be useful to the applications of magnetic resonance imaging.

H. T. Ng; K. Kim

2013-09-16T23:59:59.000Z

80

Solving Quantum Ground-State Problems with Nuclear Magnetic Resonance  

E-Print Network (OSTI)

Quantum ground-state problems are computationally hard problems; for general many-body Hamiltonians, there is no classical or quantum algorithm known to be able to solve them efficiently. Nevertheless, if a trial wavefunction approximating the ground state is available, as often happens for many problems in physics and chemistry, a quantum computer could employ this trial wavefunction to project the ground state by means of the phase estimation algorithm (PEA). We performed an experimental realization of this idea by implementing a variational-wavefunction approach to solve the ground-state problem of the Heisenberg spin model with an NMR quantum simulator. Our iterative phase estimation procedure yields a high accuracy for the eigenenergies (to the 10^-5 decimal digit). The ground-state fidelity was distilled to be more than 80%, and the singlet-to-triplet switching near the critical field is reliably captured. This result shows that quantum simulators can better leverage classical trial wavefunctions than classical computers.

Zhaokai Li; Man-Hong Yung; Hongwei Chen; Dawei Lu; James D. Whitfield; Xinhua Peng; Alán Aspuru-Guzik; Jiangfeng Du

2011-06-02T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Attainable entanglement of unitary transformed thermal states in liquid-state nuclear magnetic resonance with the chemical shift  

E-Print Network (OSTI)

Recently, Yu, Brown, and Chuang [Phys. Rev. A {\\bf 71}, 032341 (2005)] investigated the entanglement attainable from unitary transformed thermal states in liquid-state nuclear magnetic resonance (NMR). Their research gave an insight into the role of the entanglement in a liquid-state NMR quantum computer. Moreover, they attempted to reveal the role of mixed-state entanglement in quantum computing. However, they assumed that the Zeeman energy of each nuclear spin which corresponds to a qubit takes a common value for all; there is no chemical shift. In this paper, we research a model with the chemical shifts and analytically derive the physical parameter region where unitary transformed thermal states are entangled, by the positive partial transposition (PPT) criterion with respect to any bipartition. We examine the effect of the chemical shifts on the boundary between the separability and the nonseparability, and find it is negligible.

Yukihiro Ota; Shuji Mikami; Motoyuki Yoshida; Ichiro Ohba

2006-12-19T23:59:59.000Z

82

Magnetic vortices for a Ginzburg-Landau type energy with discontinuous constraint. II  

E-Print Network (OSTI)

We study vortex nucleation for minimizers of a Ginzburg-Landau energy with discontinuous constraint. For applied magnetic fields comparable with the first critical field of vortex nucleation, we determine the limiting vorticities.

Hassen Aydi; Ayman Kachmar

2008-07-08T23:59:59.000Z

83

Verification of RUC 0–1-h Forecasts and SPC Mesoscale Analyses Using VORTEX2 Soundings  

Science Conference Proceedings (OSTI)

This study uses radiosonde observations obtained during the second phase of the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) to verify base-state variables and severe-weather-related parameters calculated from Rapid ...

Michael C. Coniglio

2012-06-01T23:59:59.000Z

84

Mesoscale Convective Vortex Formation in a Weakly Sheared Moist Neutral Environment  

Science Conference Proceedings (OSTI)

Idealized simulations of a diabatic Rossby vortex (DRV) in an initially moist neutral baroclinic environment are performed using the fifth-generation National Center for Atmospheric Research–Pennsylvania State University (NCAR–PSU) Mesoscale ...

Robert J. Conzemius; Richard W. Moore; Michael T. Montgomery; Christopher A. Davis

2007-05-01T23:59:59.000Z

85

Nielsen-Olesen vortex in varying-alpha theories  

E-Print Network (OSTI)

We consider soliton solutions to Bekenstein's theory, for which the fine structure constant $\\alpha=e^2/(4\\pi\\hbar c)$ is allowed to vary due to the presence of a dielectric field pervading the vacuum. More specifically we investigate the effects of a varying $\\alpha$ upon a complex scalar field with a U(1) electromagnetic gauge symmetry subject to spontaneous symmetry breaking. We find vortex solutions to this theory, similar to the Nielsen-Olesen vortex. Near the vortex core the electric charge is typically much larger than far away from the string, lending these strings a superconducting flavour. In general the dielectric field coats the usual local string with a global string envelope. We discuss the cosmological implications of networks of such strings, with particular emphasis on their ability to generate inhomogeneous recombination scenarios. We also consider the possibility of the dielectric being a charged free field. Even though the vacuum of such a field is trivial, we find that the dielectric arranges itself in the shape of a local string, with a quantized magnetic flux at the core -- presumably borrowing these topological features from the underlying Nielsen-Olesen vortex.

J. Magueijo; H. Sandvik; T. W. B. Kibble

2001-01-15T23:59:59.000Z

86

Axial dipolar dynamo action in the Taylor-Green vortex  

E-Print Network (OSTI)

We present a numerical study of the magnetic field generated by the Taylor-Green vortex. We show that periodic boundary conditions can be used to mimic realistic boundary conditions by prescribing the symmetries of the velocity and magnetic fields. This gives insight in some problems of central interest for dynamos: the possible effect of velocity fluctuations on the dynamo threshold, the role of boundary conditions on the threshold and on the geometry of the magnetic field generated by dynamo action. In particular, we show that an axial dipolar dynamo similar to the one observed in a recent experiment can be obtained with an appropriate choice of the symmetries of the magnetic field. The nonlinear saturation is studied and a simple model explaining the magnetic Prandtl number dependence of the super/sub critical nature of the dynamo transition is given.

Giorgio Krstulovic; Gentien Thorner; Julien-Piera Vest; Stephan Fauve; Marc Brachet

2011-09-19T23:59:59.000Z

87

Vortex Ring Dyons of the SU(2) Yang-Mills-Higgs Model  

Science Conference Proceedings (OSTI)

We present an axially symmetric vortex ring dyons solutions of the SU(2) Yang-Mills-Higgs theory. These vortex rings carry electric charges that are determined by a parameter, -1{<=}{eta}{<=}1. They possess vanishing magnetic charge and are located at a ring centered around the z-axis where the Higgs field vanishes. These stationary vortex ring dyon solutions possess finite energy but they do not satisfy the first order Bogomol'nyi equations. In the Bogomol'nyi-Prasad-Sommerfield (BPS) limit where the Higgs field potential is zero, the time component of the gauge field is parallel to the Higgs field in isospace. The total energy, net electric charge and diameter of the vortex ring increase exponentially to infinity when {eta} approaches {+-}1. On the contrary, when {lambda} = 1, all these three values reach their critical value as {eta} approaches {+-}1.

Lim, Kok-Geng; Teh, Rosy; Wong, Khai-Ming [School of Physics, Universiti Sains Malaysia 11800 USM Penang (Malaysia)

2011-03-30T23:59:59.000Z

88

Gravity waves from vortex dipoles and jets  

E-Print Network (OSTI)

The dissertation first investigates gravity wave generation and propagation from jets within idealized vortex dipoles using a nonhydrostatic mesoscale model. Several initially balanced and localized jets induced by vortex dipoles are examined here. Within these dipoles, inertia-gravity waves with intrinsic frequencies 1-2 times the Coriolis parameter are simulated in the jet exit region. The ray tracing analysis reveals strong variation of wave characteristics along ray paths. The dependence of wave amplitude on the Rossby number is examined through experiments in which the two vortices are initially separated by a large distance but subsequently approach each other and form a vortex dipole with an associated amplifying localized jet. The amplitude of stationary gravity waves in the simulations with a 90-km grid spacing increases nearly linearly with the square of the Rossby number but significantly more rapidly when smaller grid spacing is used. To further address the source mechanism of the gravity waves within the vortex dipole, a linear numerical framework is developed based on the framework proposed by Plougonven and Zhang (2007). Using the nonlinearly balanced fields as the basic state and driven by three types of large scale forcing, the vorticity, divergence and thermodynamic forcing, this linear model is utilized to obtain linear wave responses. The wave packets in the linear responses compare reasonably well with the MM5 simulated gravity waves. It is suggested that the vorticity forcing is the leading contribution to both gravity waves in the jet exit region and the ascent/descent feature in the jet core. This linear model is also adopted to study inertia-gravity waves in the vicinity of a baroclinic jet during the life cycle of an idealized baroclinic wave. It is found that the thermodynamic forcing and the vorticity forcing are equally important to the gravity waves in the low stratosphere, but the divergence forcing is again playing a lesser role. Two groups of wave packets are present in the linear responses; their sources appear to locate either near the surface front or near the middle/upper tropospheric jet.

Wang, Shuguang

2008-08-01T23:59:59.000Z

89

Discrete variable representation for highly excited states of hydrogen atoms in magnetic fields  

SciTech Connect

A discrete variable representation (DVR) appropriate for describing the highly excited states of hydrogen atoms in laboratory-strength magnetic fields is constructed by using a symmetry-adapted direct product of one-dimensional DVR{close_quote}s in parabolic coordinates related to generalized Gauss-Laguerre quadratures. The resulting sparse Hamiltonian matrix is used in an iterative (filter-diagonalization) procedure to obtain eigenvalues and eigenvectors in a given spectral domain. The method is applied to calculate eigenvalues and lifetimes of {open_quotes}circular{close_quotes} Rydberg states, as well as oscillator strengths for the excitation of highly excited states. {copyright} {ital 1997} {ital The American Physical Society}

Grozdanov, T.P.; Andric, L.; Manescu, C.; McCarroll, R. [Laboratoire de Dynamique des Ions, Atomes et Molecules (URA 774 du CNRS), Universite Pierre et Marie Curie, 4 Place Jussieu T12-B75, 75252 Paris Cedex 05 (France); Grozdanov, T.P. [Institute of Physics, P.O. Box 57, 11001 Belgrade (Yugoslavia)

1997-09-01T23:59:59.000Z

90

Transformed Eliassen Balanced Vortex Model  

Science Conference Proceedings (OSTI)

We consider the axisymmetric balanced flow occurring in a thermally forced vortex in which the frictional inflow is confined to a thin boundary layer. Above the boundary layer the absolute angular momentum ½fR2=rv+½fr2 is conserved. We refer to R ...

Wayne H. Schubert; James J. Hack

1983-06-01T23:59:59.000Z

91

Measurement of the magnetic fine structure of the 10G and 10H states of helium  

Science Conference Proceedings (OSTI)

The magnetic fine-structure intervals separating the four members of the 10G and 10H manifolds of helium have been measured with a precision of 0.1% using a fast-beam microwave-optical resonance technique. The results are found to be in good agreement with theory, illustrating that the two-electron wave function is very nearly hydrogenic. The measurements are also used to determine the small exchange energies of the 10G and 10H states.

Hessels, E.A.; Sturrus, W.G.; Lundeen, S.R.; Cok, D.R.

1987-06-01T23:59:59.000Z

92

Speedup of quantum state transfer by three- qubit interactions: Implementation by nuclear magnetic resonance  

E-Print Network (OSTI)

Universal quantum information processing requires single-qubit rotations and two-qubit interactions as minimal resources. A possible step beyond this minimal scheme is the use of three-qubit interactions. We consider such three-qubit interactions and show how they can reduce the time required for a quantum state transfer in an XY spin chain. For the experimental implementation, we use liquid-state nuclear magnetic resonance (NMR), where three-qubit interactions can be implemented by sequences of radio-frequency pulses.

Jingfu Zhang; Xinhua Peng; Dieter Suter

2005-12-25T23:59:59.000Z

93

Polarization radiation of vortex electrons with large orbital angular momentum  

E-Print Network (OSTI)

Vortex electrons, - freely propagating electrons whose wavefunction has helical wavefronts, - could become a novel tool in the physics of electromagnetic radiation. They carry a non-zero intrinsic orbital angular momentum (OAM) $\\ell$ with respect to the propagation axis and, for \\ell \\gg 1, a large OAM-induced magnetic moment, \\mu ~ \\ell \\mu_B (\\mu_B is the Bohr magneton), which influences the radiation of electromagnetic waves. Here, we consider in detail the OAM-induced effects by such electrons in two forms of polarization radiation, namely in Cherenkov radiation and transition radiation. Thanks to the large \\ell, we can neglect quantum or spin-induced effects, which are of the order of \\hbar \\omega/E_e \\ll 1, but retain the magnetic moment contribution \\ell \\hbar \\omega/E_e \\lesssim 1, which makes the quasiclassical approach to polarization radiation applicable. We discuss the magnetic moment contribution to polarization radiation, which has never been experimentally observed, and study how its visibility depends on the kinematical parameters and the medium permittivity. In particular, it is shown that this contribution can, in principle, be detected in azimuthally non-symmetrical problems, for example when vortex electrons obliquely cross a metallic screen (transition radiation) or move nearby it (diffraction radiation). We predict a left-right angular asymmetry of the transition radiation (in the plane where the charge radiation distributions would stay symmetric), which appears due to an effective interference between the charge radiation field and the magnetic moment one. Numerical values of this asymmetry for vortex electrons with E_e = 300keV and \\ell = O(100-1000) are O(0.1-1%), and we argue that this effect could be detected with existing technology. The finite conductivity of the target and frequency dispersion play the crucial roles in these predictions.

Igor P. Ivanov; Dmitry V. Karlovets

2013-05-28T23:59:59.000Z

94

Simulations of Dual-Vortex Interaction within Environmental Shear  

Science Conference Proceedings (OSTI)

For over a century it has been known that each vortex in a multiple vortex configuration will move in response to the other vortices. However, despite advances since that time, the complexities of multiple vortex scenarios when sheared ...

Robert E. Hart; Jenni L. Evans

1999-11-01T23:59:59.000Z

95

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states by a small alternating magnetic field, it could serve as a memory bit in future magnetic memory devices. However, these magnetic structures often contain numerous imperfections such as domain wall pinning sites, which have to be taken into account for the practical application of such systems. To study how these defects affect the dynamics of magnetic vortices, researchers from Belgium, Germany, and the United States investigated square-shaped and disk-shaped thin-film structures with artificially introduced imperfections in the form of nanometer-sized holes. They used time-resolved scanning transmission x-ray microscopy (STXM) at ALS Beamline 11.0.2 to determine the frequency at which these vortices vibrate (their eigenfrequency). The imperfections were found to cause a higher vibrational frequency in square-shaped structures, but did not influence the disk-shaped structures. Knowledge of the frequency is crucial for vortex-based memories, since the electric signal for writing data needs to be precisely tuned to it.

96

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states by a small alternating magnetic field, it could serve as a memory bit in future magnetic memory devices. However, these magnetic structures often contain numerous imperfections such as domain wall pinning sites, which have to be taken into account for the practical application of such systems. To study how these defects affect the dynamics of magnetic vortices, researchers from Belgium, Germany, and the United States investigated square-shaped and disk-shaped thin-film structures with artificially introduced imperfections in the form of nanometer-sized holes. They used time-resolved scanning transmission x-ray microscopy (STXM) at ALS Beamline 11.0.2 to determine the frequency at which these vortices vibrate (their eigenfrequency). The imperfections were found to cause a higher vibrational frequency in square-shaped structures, but did not influence the disk-shaped structures. Knowledge of the frequency is crucial for vortex-based memories, since the electric signal for writing data needs to be precisely tuned to it.

97

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states by a small alternating magnetic field, it could serve as a memory bit in future magnetic memory devices. However, these magnetic structures often contain numerous imperfections such as domain wall pinning sites, which have to be taken into account for the practical application of such systems. To study how these defects affect the dynamics of magnetic vortices, researchers from Belgium, Germany, and the United States investigated square-shaped and disk-shaped thin-film structures with artificially introduced imperfections in the form of nanometer-sized holes. They used time-resolved scanning transmission x-ray microscopy (STXM) at ALS Beamline 11.0.2 to determine the frequency at which these vortices vibrate (their eigenfrequency). The imperfections were found to cause a higher vibrational frequency in square-shaped structures, but did not influence the disk-shaped structures. Knowledge of the frequency is crucial for vortex-based memories, since the electric signal for writing data needs to be precisely tuned to it.

98

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic  

NLE Websites -- All DOE Office Websites (Extended Search)

Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in ultrafast computer memories. In such systems, the otherwise in-plane magnetization turns perpendicular to the plane at the center of the vortex, forming the vortex core. Because such a core has two possible polarizations (up or down) and can be switched between these two states by a small alternating magnetic field, it could serve as a memory bit in future magnetic memory devices. However, these magnetic structures often contain numerous imperfections such as domain wall pinning sites, which have to be taken into account for the practical application of such systems. To study how these defects affect the dynamics of magnetic vortices, researchers from Belgium, Germany, and the United States investigated square-shaped and disk-shaped thin-film structures with artificially introduced imperfections in the form of nanometer-sized holes. They used time-resolved scanning transmission x-ray microscopy (STXM) at ALS Beamline 11.0.2 to determine the frequency at which these vortices vibrate (their eigenfrequency). The imperfections were found to cause a higher vibrational frequency in square-shaped structures, but did not influence the disk-shaped structures. Knowledge of the frequency is crucial for vortex-based memories, since the electric signal for writing data needs to be precisely tuned to it.

99

Solid state nuclear magnetic resonance methodology and applications to structure determination of peptides, proteins and amyloid fibrils  

E-Print Network (OSTI)

Several methodological developments and applications of multidimensional solid-state nuclear magnetic resonance to biomolecular structure determination are presented. Studies are performed in uniformly 3C, 15N isotope ...

Jaroniec, Christopher P

2003-01-01T23:59:59.000Z

100

Asymptotics of the ground state energy for atoms and molecules in the self-generated magnetic field  

E-Print Network (OSTI)

Asymptotics of the ground state energy of the heavy atoms and molecules in the self-generated magnetic field has been derived and for minimal energy positions of nuclei remainder estimate $O(N^{16/9})$ has been recovered.

Ivrii, Victor

2011-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Asymptotics of the ground state energy for atoms and molecules in the self-generated magnetic field  

E-Print Network (OSTI)

Asymptotics of the ground state energy of the heavy atoms and molecules in the self-generated magnetic field has been derived and for minimal energy positions of nuclei remainder estimate $O(N^{16/9})$ has been recovered.

Victor Ivrii

2011-12-23T23:59:59.000Z

102

Evidence for the microscopic formation of mixed-symmetry states from magnetic moment measurements  

SciTech Connect

Using the transient field technique, the magnetic moments of the second excited 2{sup +} states in {sup 92,94}Zr have been measured for the first time. The large positive g factors, g(2{sub 2}{sup +};{sup 92}Zr)=+0.76(50) and g(2{sub 2}{sup +};{sup 94}Zr)=+0.88(27), which are in contrast to the known negative g factors of the 2{sub 1}{sup +} states, are found to be a consequence of weak proton-neutron coupling combined with the Z=40 subshell closure. From their large M1 transition strengths to the 2{sub 1}{sup +} states, in earlier works an assignment to the 2{sub 2}{sup +} states as proton-neutron symmetric and mixed-symmetry states has been made, which are now found to be polarized in their proton-neutron content. This fact allows to identify the underlying microscopic main configurations in the wave functions, which form the building blocks of symmetric and mixed-symmetry states in this region as valence nucleons are added and shell structure changes.

Werner, V.; Ai, H.; Casperson, R. J.; Casten, R. F.; Eckel, S.; Heinz, A.; Lambie-Hanson, C.; McCutchan, E. A.; Meyer, D. A.; Qian, J.; Schmidt, A.; Williams, E.; Winkler, R. [Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520-8124 (United States); Benczer-Koller, N.; Kumbartzki, G.; Boutachkov, P. [Department of Physics and Astronomy, Rutgers University, New Brunswick, New Jersey 08903 (United States); Holt, J. D. [TRIUMF, Vancouver (Canada); Stefanova, E. [Department of Physics and Astronomy, Rutgers University, New Brunswick, New Jersey 08903 (United States); Institute for Nuclear Research and Nuclear Energy, BAS, 1784 Sofia (Bulgaria); Perry, M. [Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520-8124 (United States); Department of Physics, Florida State University, Florida (United States); Pietralla, N. [Institut fuer Kernphysik, TU Darmstadt, D-64289 Darmstadt (Germany)] (and others)

2008-09-15T23:59:59.000Z

103

Ground state energy of large atoms in a self-generated magnetic field  

E-Print Network (OSTI)

We consider a large atom with nuclear charge $Z$ described by non-relativistic quantum mechanics with classical or quantized electromagnetic field. We prove that the absolute ground state energy, allowing for minimizing over all possible self-generated electromagnetic fields, is given by the non-magnetic Thomas-Fermi theory to leading order in the simultaneous $Z\\to \\infty$, $\\al\\to 0$ limit if $Z\\al^2\\leq \\kappa$ for some universal $\\kappa$, where $\\al$ is the fine structure constant.

Laszlo Erdos; Jan Philip Solovej

2009-03-10T23:59:59.000Z

104

The idea of vortex energy  

E-Print Network (OSTI)

This work formulates and gives grounds for general principles and theorems that question the energy function doctrine and its quantum version as a genuine law of nature without borders of adequacy. The emphasis is on the domain where the energy of systems is conserved -- I argue that only in its tiny part the energy is in the kinetic, potential and thermal forms describable by a generalized thermodynamic potential, whereas otherwise the conserved energy constitutes a whole linked to vortex forces, and can be a factor of things like persistent currents and dark matter.

V. E. Shapiro

2011-09-12T23:59:59.000Z

105

Nonlinear motion of coupled magnetic vortices in ferromagnetic/non-magnetic/ferromagnetic trilayer  

SciTech Connect

We have investigated a coupled motion of two vortex cores in ferromagnetic/nonmagnetic/ferromagnetic trilayer cynliders by means of micromagnetic simulation. Dynamic motion of two vortex with parallel and antiparallel relative chiralities of curling spins around the vortex cores have been examined after excitation by 1-ns pulsed external field. With systematic variation in non-magnetic spacer layer thickness from 0 to 20 nm, the coupling between two cores becomes significant as the spacer becomes thinner. Significant coupling leads to a nonlinear chaotic coupled motion of two vortex cores for the parallel chiralities and a faster coupled gyrotropic oscillation for the antiparallel chiralities.

Jun, Su-Hyeong; Shim, Je-Ho; Oh, Suhk-Kun; Yu, Seong-Cho; Kim, Dong-Hyun; Mesler, Brooke; Fischer, Peter

2009-07-05T23:59:59.000Z

106

Reversing the Circulation of Magnetic Vortices  

NLE Websites -- All DOE Office Websites (Extended Search)

a magnetic vortex are not actually swirling around the core. What they can do is flip in place, and the core-defined as the area where spins point out of the plane-can be...

107

Stable optical vortex solitons in pair plasmas  

Science Conference Proceedings (OSTI)

It is shown that the pair plasmas with small temperature asymmetry can support existence of localized as well as delocalized optical vortex solitons. Coexistence of such solitons is possible due to peculiar form of saturating nonlinearity which has a focusing-defocusing nature--for weak amplitudes being focusing becoming defocusing for higher amplitudes. It is shown that delocalized vortex soliton is stable in entire region of its existence while single- and multicharged localized vortex solitons are unstable for low amplitudes and become stable for relativistic amplitudes.

Berezhiani, V. I.; Shatashvili, N. L. [Plasma Physics Department, Andronikashvili Institute of Physics, Tbilisi 0177 (Georgia); Department of Physics, Faculty of Exact and Natural Sciences, Javakhishvili Tbilisi State University, Tbilisi 0128 (Georgia); Mahajan, S. M. [Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States)

2010-05-15T23:59:59.000Z

108

Improved methods for calculating thermodynamic properties of magnetic systems using Wang-Landau density of states  

SciTech Connect

The Wang-Landau method [F. Wang and D. P. Landau, Phys. Rev. E 64, 056101 (2001)] is an efficient way to calculate the density of states (DOS) for magnetic systems, and the DOS can then be used to rapidly calculate the thermodynamic properties of the system. A technique is presented that uses the DOS for a simple Hamiltonian to create a stratified sample of configurations which are then used calculate a warped DOS for more realistic Hamiltonians. This technique is validated for classical models of bcc Fe with exchange interactions of increasing range, but its real value is using the DOS for a model Hamiltonian calculated on a workstation to select the stratified set of configurations whose energies can then be calculated for a density-functional Hamiltonian. The result is an efficient first-principles calculation of thermodynamic properties such as the specific heat and magnetic susceptibility. Another technique uses the sample configurations to calculate the parameters of a model exchange interaction using a least-squares approach. The thermodynamic properties can be subsequently evaluated using traditional Monte Carlo techniques for the model exchange interaction. Finally, a technique that uses the configurations to train a neural network to estimate the configuration energy is also discussed. This technique could potentially be useful in identifying the configurations most important in calculating the warped DOS. VC2011 American Institute of Physics. [doi:10.1063/1.3565413

Brown, Greg [ORNL; Rusanu, Aurelian [ORNL; Daene, Markus W [ORNL; Nicholson, Don M [ORNL; Eisenbach, Markus [ORNL; Fidler, Jane L [ORNL

2011-01-01T23:59:59.000Z

109

Bubble Behavior in a Taylor Vortex  

E-Print Network (OSTI)

We present an experimental study on the behavior of bubbles captured in a Taylor vortex. The gap between a rotating inner cylinder and a stationary outer cylinder is filled with a Newtonian mineral oil. Beyond a critical ...

Deng, Rensheng

110

Barotropic Vortex Evolution on a Beta Plane  

Science Conference Proceedings (OSTI)

A barotropic, primitive equation (shallow water) model is used on the beta plane to investigate the influence of divergence, total relative angular momentum (RAM) and advective nonlinearities on the evolution of a hurricane-like vortex. The ...

Lloyd J. Shapiro; Katsuyuki V. Ooyama

1990-01-01T23:59:59.000Z

111

Vortex Hydro Energy - National Renewable Energy Laboratory  

Vortex Hydro Energy, LLC Michael M. Bernitsas Ph.D., CEO and CTO Gus Simiao MSE, MBA, Dir. of Business Development NREL’s 20th Annual, Industry Growth Forum

112

Vortex-Driven Sensitivity in Deformation Flow  

Science Conference Proceedings (OSTI)

A sensitivity mechanism for the interaction of two vortices in a two-dimensional deformation background flow is explored. A nonlinear model describing the vortex interaction up to a critical merging distance is developed. This model shows that in ...

Zhiyuan Liu; Paul J. Roebber

2008-12-01T23:59:59.000Z

113

magnets  

NLE Websites -- All DOE Office Websites (Extended Search)

I I Painless Physics Articles BEAM COOLING August 2, 1996 By Leila Belkora, Office of Public Affairs ACCELERATION August 16, 1996 By Dave Finley, Accelerator Division Head RF August 30, 1996 By Pat Colestock, Accelerator Division FIXED TARGET PHYSICS September 20, 1996 By Peter H. Garbincius, Physics Section FIXED TARGET PHYSICS PART DEUX October 16, 1996 By Peter H. Garbincius, Physics Section and Leila Belkora, Office of Public Affaris CROSS SECTION November 1, 1996 By Doreen Wackeroth, Theoretical Physics Edited by Leila Belkora, Office of Public Affaris MAGNETS PART I November 15, 1996 By Hank Glass, Technical Support Section Edited by Donald Sena, Office of Public Affairs MAGNETS PART II January 10, 1997 By Hank Glass, Technical Support Section Edited by Donald Sena, Office of Public Affairs

114

Synthesis and magnetic reversal of bi-conical Ni nanostructures  

SciTech Connect

Template synthesis in polyethylene terephthalate (PET) membranes has been used to grow hour glass shaped nickel nanowires with a constriction in the range of tens of nanometers at the center. Anisotropic magnetoresistance measurements have been performed on a single nanowire to follow magnetization reversal of the structure. The results are explained via 3D micromagnetic simulations showing the appearance of a complex vortex state close to the constriction whose propagation depends on the angle between the cone axis and the applied field. The interest of this original growth process for spintronics is discussed.

Biziere, N. [Laboratoire des Solides Irradies, CEA/CNRS/Ecole Polytechnique, Ecole Polytechnique, 91128 Palaiseau Cedex (France); CEMES-CNRS, 29 Rue Jeanne Marvig, 31055 Toulouse (France); Lassalle Ballier, R.; Viret, M. [Service de Physique de l' Etat Condense, DSM/IRAMIS/SPEC, CEA Saclay URA CNRS 2464, 91191 Gif-Sur-Yvette Cedex (France); Clochard, M. C.; Wade, T. L.; Wegrowe, J. E. [Laboratoire des Solides Irradies, CEA/CNRS/Ecole Polytechnique, Ecole Polytechnique, 91128 Palaiseau Cedex (France); Balanzat, E. [CIMAP, Unite Mixte CEA-CNRS-ENSICAEN, F-14070 Caen Cedex 5 (France)

2011-09-15T23:59:59.000Z

115

Characterization of proton exchange membrane materials for fuel cells by solid state nuclear magnetic resonance  

Science Conference Proceedings (OSTI)

Solid-state nuclear magnetic resonance (NMR) has been used to explore the nanometer-scale structure of Nafion, the widely used fuel cell membrane, and its composites. We have shown that solid-state NMR can characterize chemical structure and composition, domain size and morphology, internuclear distances, molecular dynamics, etc. The newly-developed water channel model of Nafion has been confirmed, and important characteristic length-scales established. Nafion-based organic and inorganic composites with special properties have also been characterized and their structures elucidated. The morphology of Nafion varies with hydration level, and is reflected in the changes in surface-to-volume (S/V) ratio of the polymer obtained by small-angle X-ray scattering (SAXS). The S/V ratios of different Nafion models have been evaluated numerically. It has been found that only the water channel model gives the measured S/V ratios in the normal hydration range of a working fuel cell, while dispersed water molecules and polymer ribbons account for the structures at low and high hydration levels, respectively.

Kong, Zueqian

2010-03-15T23:59:59.000Z

116

Wigner distribution function and entanglement of generalized quantum optical vortex  

E-Print Network (OSTI)

We calculate the Wigner (quasi)probability distribution function of the quantum optical elliptical vortex (QEV), generated by coupling squeezed vacuum states of two modes. The coupling between the two modes is performed by using beam splitter (BS) or a dual channel directional coupler (DCDC). The quantum interference due to the coupling between the two modes promises the generation of controlled entanglement for quantum computation and quantum tomography. We compute the entanglement of such QEV formed by non-classical radiation field, using Wigner function. We report a critical squeezing parameter above which the entanglement is less for higher vorticity, which is counter intuitive.

Abir Bandyopadhyay; Shashi Prabhakar; R. P. Singh

2011-01-25T23:59:59.000Z

117

Low NOx Advanced Vortex Combustor  

SciTech Connect

A lean-premixed advanced vortex combustor (AVC) has been developed and tested. The natural gas fueled AVC was tested at the U.S. Department of Energy’s National Energy Technology Laboratory in Morgantown, WV. All testing was performed at elevated pressures and inlet temperatures and at lean fuel-air ratios representative of industrial gas turbines. The improved AVC design exhibited simultaneous NOx /CO/unburned hydrocarbon (UHC) emissions of 4/4/0 ppmv (all emissions corrected to 15% O2 dry). The design also achieved less than 3 ppmv NOx with combustion efficiencies in excess of 99.5%. The design demonstrated marked acoustic dynamic stability over a wide range of operating conditions, which potentially makes this approach significantly more attractive than other lean-premixed combustion approaches. In addition, the measured 1.75% pressure drop is significantly lower than conventional gas turbine combustors, which could translate into an overall gas turbine cycle efficiency improvement. The relatively high velocities and low pressure drop achievable with this technology make the AVC approach an attractive alternative for syngas fuel applications.

Edmonds, R.G. (Ramgen Power Systems, Inc., Bellevue, WA); Williams, J.T. (Ramgen Power Systems, Inc., Bellevue, WA); Steele, R.C. (EPRI); Straub, D.L.; Casleton, K.H.; Bining, Avtar (California Energy Commission, Sacramento, CA)

2008-05-01T23:59:59.000Z

118

The Effect of Vorticity-Profile Shape on the Instability of a Two-Dimensional Vortex  

Science Conference Proceedings (OSTI)

A simple linear numerical model is used to study the effect of the shape of the vertical vorticity profile on the stability characteristics of a two-dimensional vortex. In all cases, the basic-state vorticity is confined to an annulus. It is ...

Jerry L. Steffens

1988-01-01T23:59:59.000Z

119

Mitigation of Wind Turbine/Vortex Interaction Using Disturbance Accommodating Control  

DOE Green Energy (OSTI)

Wind turbines, a competitive source of emission-free electricity, are being designed with diameters and hub heights approaching 100 m, to further reduce the cost of the energy they produce. At this height above the ground, the wind turbine is exposed to atmospheric phenomena such as low-level jets, gravity waves, and Kelvin-Helmholtz instabilities, which are not currently modeled in wind turbine design codes. These atmospheric phenomena can generate coherent turbulence that causes high cyclic loads on wind turbine blades. These fluctuating loads lead to fatigue damage accumulation and blade lifetime reduction. Advanced control was used to mitigate vortex-induced blade cyclic loading. A full-state feedback controller that incorporates more detailed vortex inputs achieved significantly greater blade load reduction. Blade loads attributed to vortex passage, then, can be reduced through advanced control, and further reductions appear feasible.

Hand, M. M.

2003-12-01T23:59:59.000Z

120

Direct observation of a magnetic Bose glass  

Science Conference Proceedings (OSTI)

A Bose glass is a novel state of matter that emerges in systems of interacting bosons in the presence of quenched disorder. At sufficiently low temperatures, disorder-free bosons are subject to so-called Bose-Einstein condensation (BEC). BEC can involve atoms in liquid 4He, laser-cooled ions in magnetic traps,2 Cooper pairs in superconductors, or magnons in magnetic systems. Due to peculiarities of Bose statistics, particles lose their individuality and occupy a unique quantum-mechanical state. The wave function of this condensate establishes long-range quantum phase coherence across a macroscopic sample. This, in turn, spawns unique quantum phenomena such as superfluity,5 Josephson effect6 and vortex matter. For repulsive bosons, quenched disorder disrupts the condensate and interferes with phase coherence. The result is a peculiar glassy state with only short-range phase correlations. While some experimental evidence of this was found in ultracold atoms,9 novel high-temperature superconductors,10 and quantum magnets,11, 12 none of the studies were direct. The key characteristic, namely the wave function of the condensate disrupted by disorder on the microscopic scale, remained inaccessible. Hereby we report a direct neutron diffraction observation of short range correlations of the BEC order parameter in a magnetic Bose glass. This phase is realized in the quantum spin ladder compound IPA-Cu(Cl0.96Br0.04)3, where disorder is induced by random chemical substitution.

Hong, Tao [ORNL; Zheludev, Andrey I [ORNL; Manaka, H. [Kagoshima University, Kagoshima JAPAN; Regnault, L.-P. [CEA, Grenoble, France

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Interactions between a Submesoscale Anticyclonic Vortex and a Front  

Science Conference Proceedings (OSTI)

The evolution of a submesoscale anticyclonic vortex was observed by high-frequency Doppler radio current meters and satellite radiometers. The vortex formed between two large cyclones to the southwest of Oahu, Hawaii. The radius of the core was ...

Cédric Chavanne; Pierre Flament; Klaus-Werner Gurgel

2010-08-01T23:59:59.000Z

122

Nonlinear Motion of a Shallow Water Barotropic Vortex  

Science Conference Proceedings (OSTI)

Nonlinear motions of a shallow water barotropic vortex on a ? plane differ substantially from the analogous linear motions. The nonlinear model described here, in which wavenumber 1–3 asymmetries interact with each other and the mean vortex, ...

H. E. Willoughby

1994-12-01T23:59:59.000Z

123

A Highly Configurable Vortex Initialization Method for Tropical Cyclones  

Science Conference Proceedings (OSTI)

A highly configurable vortex initialization methodology has been constructed in order to permit manipulation of the initial vortex structure in numerical models of tropical cyclones. By using distinct specifications of the flow in the boundary ...

Eric D. Rappin; David S. Nolan; Sharanya J. Majumdar

2013-10-01T23:59:59.000Z

124

A Highly Configurable Vortex Initialization Method for Tropical Cyclones  

Science Conference Proceedings (OSTI)

A highly configurable vortex initialization methodology has been constructed in order to permit manipulation of the initial vortex structure in numerical models of tropical cyclones. By using distinct specifications of the flow in the boundary ...

Eric D. Rappin; David S. Nolan; Sharanya J. Majumdar

125

Case Study of an Orographically Induced Mesoscale Vortex (Denver Cyclone)  

Science Conference Proceedings (OSTI)

Observations taken during the Convection Initiation and Downburst Experiment (CINDE) are used to describe the formation and structure of an orographically induced mesoscale vortex that frequently occurs in northeastern Colorado. This vortex, ...

J. M. Wilczak; T. W. Christian

1990-05-01T23:59:59.000Z

126

Stabilization of vortex solitons in nonlocal nonlinear media  

SciTech Connect

We study the evolution of vortex solitons in optical media with a nonlocal nonlinear response. We employ a modulation theory for the vortex parameters based on an averaged Lagrangian, and analyze the azimuthal evolution of both the vortex width and diffractive radiation. We describe analytically the physical mechanism for vortex stabilization due to the long-range nonlocal nonlinear response, the effect observed earlier in numerical simulations only.

Minzoni, Antonmaria A. [Fenomenos Nonlineales y Mecanica (FENOMEC), Department of Mathematics and Mechanics, Instituto de Investigacion en Matematicas Aplicadas y Sistemas, Universidad Nacional Autonoma de Mexico, 01000 Mexico D.F. (Mexico); Smyth, Noel F. [School of Mathematics and Maxwell Institute for Mathematical Sciences, University of Edinburgh, Edinburgh EH9 3JZ, Scotland (United Kingdom); Worthy, Annette L. [School of Mathematics and Applied Statistics, University of Wollongong, Wollongong NSW 2522 (Australia); Kivshar, Yuri S. [Nonlinear Physics Center, Research School of Physical Sciences and Engineering, Australian National University, Canberra ACT 0200 (Australia)

2007-12-15T23:59:59.000Z

127

Liquid-State NMR and Scalar Couplings in Microtesla Magnetic Fields  

ference in free energy of solvation between the ... K. S. Richardson, Mechanism and Theory in Organic Chemistry ... We obtained nuclear magnetic resonance ...

128

A Study of Premixed Propagating Flame Vortex Interaction  

Science Conference Proceedings (OSTI)

Experimental data is presented for the interaction between a propagating flame and a simple vortex flow field structure generated in the wake of solid obstacles. The interaction between gas movement and obstacles creates vortex shedding forming a simple ... Keywords: Combustion, Flame/Vortex, PIV, Visualization

G. K. Hargrave; S. Jarvis

2006-04-01T23:59:59.000Z

129

Simulation of a Heisenberg XY- chain and realization of a perfect state transfer algorithm using liquid nuclear magnetic resonance  

E-Print Network (OSTI)

The three- spin chain with Heisenberg XY- interaction is simulated in a three- qubit nuclear magnetic resonance (NMR) quantum computer. The evolution caused by the XY- interaction is decomposed into a series of single- spin rotations and the $J$- coupling evolutions between the neighboring spins. The perfect state transfer (PST) algorithm proposed by M. Christandl et al [Phys. Rev. Lett, 92, 187902(2004)] is realized in the XY- chain.

Jingfu Zhang; Gui Lu Long; Wei Zhang; Zhiwei Deng; Wenzhang Liu; Zhiheng Lu

2005-03-25T23:59:59.000Z

130

Controlled Vortex Breakdown on Modified Delta Wings  

Science Conference Proceedings (OSTI)

This paper studies the effect of perturbation to the breakdown of the leading-edge vortices over delta wings. The passive perturbation in the normal direction is achieved by installing the hemisphere-like bulges on the delta wing along the projection ... Keywords: Bulge perturbation, Delta wing, Vortex breakdown

S. Srigrarom; N. Lewpiriyawong

2007-08-01T23:59:59.000Z

131

The Tornadic Vortex Signature: An Update  

Science Conference Proceedings (OSTI)

A tornadic vortex signature (TVS) is a degraded Doppler velocity signature of a tornado that occurs when the core region of a tornado is smaller than the half-power beamwidth of the sampling Doppler radar. Soon after the TVS was discovered in the ...

Rodger A. Brown; Vincent T. Wood

2012-04-01T23:59:59.000Z

132

Vortex operators in gauge field theories  

SciTech Connect

Several related aspects of the 't Hooft vortex operator are studied. The current picture of the vacuum of quantum chromodynamics, the idea of dual field theories, and the idea of the vortex operator are reviewed first. The Abelian vortex operator written in terms of elementary fields and the calculation of its Green's functions are considered. A two-dimensional solvable model of a Dirac string is presented. The expression of the Green's functions more neatly in terms of Wu and Yang's geometrical idea of sections is addressed. The renormalization of the Green's functions of two kinds of Abelian looplike operators, the Wilson loop and the vortex operator, is studied; for both operators only an overall multiplicative renormalization is needed. In the case of the vortex this involves a surprising cancellation. Next, the dependence of the Green's functions of the Wilson and 't Hooft operators on the nature of the vacuum is discussed. The cluster properties of the Green's functions are emphasized. It is seen that the vortex operator in a massive Abelian theory always has surface-like clustering. The form of Green's functions in terms of Feynman graphs is the same in Higgs and symmetric phases; the difference appears in the sum over all tadpole trees. Finally, systems having fields in the fundamental representation are considered. When these fields enter only weakly into the dynamics, a vortex-like operator is anticipated. Any such operator can no longer be local looplike, but must have commutators at long range. A U(1) lattice gauge theory with two matter fields, one singly charged (fundamental) and one doubly charged (adjoint), is examined. When the fundamental field is weakly coupled, the expected phase transitions are found. When it is strongly coupled, the operator still appears to be a good order parameter, a discontinuous change in its behavior leads to a new phase transition. 18 figures.

Polchinski, J.

1980-07-01T23:59:59.000Z

133

A polyoxommetalate-based single-molecule magnet with an S = 21/2 ground state  

SciTech Connect

Ligand modification transforms a polyoxometalate-anchored cubane-type [Mn{sup III}{sub 3}Mn{sup IV}O{sub 4}] core into a centrosymmetric [Mn{sup III}{sub 6}Mn{sup IV}O{sub 8}] di-cubane cluster, and restores the slow magnetization relaxation characteristics typical for [Mn{sub 4}O{sub 4}] cubane-based single-molecule magnets.

Fang, Xikui; Koegerler, Paul; Luban, Marshal; Speldrich, Manfred; Schilder, Helmut

2012-01-30T23:59:59.000Z

134

The dependence of chemistry on the inlet equivalence ratio in vortex-flame interactions [Printed LBNL report with title: The effect of stoichiometry on vortex flame interactions  

E-Print Network (OSTI)

of stoichiometry on vortex flame interactions [31] Pember,Rosalik, M . E . , Combust. Flame, 112(3):342-358 (1998).of stoichiometry on vortex flame interactions [15] Mueller,

Tonse, Shaheen R.

2011-01-01T23:59:59.000Z

135

The dependence of chemistry on the inlet equivalence ratio in vortex-flame interactions [Printed LBNL report with title: The effect of stoichiometry on vortex flame interactions  

E-Print Network (OSTI)

of stoichiometry on vortex flame interactions [31] Pember,Rosalik, M . E . , Combust. Flame, 112(3):342-358 (1998).of stoichiometry on vortex flame interactions [15] Mueller,

Bell, John B.; Brown, Nancy J.; Day, Marcus S.; Frenklach, Michael; Grcar, Joseph F.; Tonse, Shaheen R.

1999-01-01T23:59:59.000Z

136

Vortex Generation Through Balanced Adjustment  

Science Conference Proceedings (OSTI)

The problem of geostrophic adjustment, originally considered by C.G. Rossby, is solved in an axisymmetric geometry for a continuously stratified fluid, where the adjusted final state is in hydrostatic, gradient-wind balance. This problem is ...

James C. McWilliams

1988-08-01T23:59:59.000Z

137

Solid-State NMR Studies of Fossil Fuels using One- and Two-Dimensional Methods at High Magnetic Field  

Science Conference Proceedings (OSTI)

We examine the opportunities offered by advancements in solid-state NMR (SSNMR) methods, which increasingly rely on the use of high magnetic fields and fast magic angle spinning (MAS), in the studies of coals and other carbonaceous materials. The sensitivity of one- and two-dimensional experiments tested on several Argonne Premium coal samples is only slightly lower than that of traditional experiments performed at low magnetic fields in large MAS rotors, since higher receptivity per spin and the use of 1H detection of low-gamma nuclei can make up for most of the signal loss due to the small rotor size. The advantages of modern SSNMR methodology in these studies include improved resolution, simplicity of pulse sequences, and the possibility of using J-coupling during mixing.

Althaus, Stacey M.; Mao, Kanmi; Kennedy, Gordon J.; Pruski, Marek

2012-06-24T23:59:59.000Z

138

Effects of Magnetic Field on the Turbulent Wake of a Cylinder in MHD Channel Flow  

SciTech Connect

Results from a free-surface MHD flow experiment are presented detailing the modi cation of vortices in the wake of a circular cylinder with its axis parallel to the applied magnetic fi eld. Experiments were performed with a Reynolds number near Re ~ 104 as the interaction parameter, N = |j x#2; B| / |? (? ? ?), was increased through unity. By concurrently sampling the downstream fluid velocity at sixteen cross-stream locations in the wake, it was possible to extract an ensemble of azimuthal velocity profi les as a function of radius for vortices shed by the cylinder at varying strengths of magnetic field. Results indicate a signi cant change in vortex radius and rotation as N is increased. The lack of deviations from the vortex velocity pro file at high magnetic fi elds suggests the absence of small-scale turbulent features. By sampling the wake at three locations downstream in subsequent experiments, the decay of the vortices was examined and the effective viscosity was found to decrease as N-049±0.4. This reduction in effective viscosity is due to the modi cation of the small-scale eddies by the magnetic fi eld. The slope of the energy spectrum was observed to change from a k-1.8 power-law at low N to a k-3.5 power-law for N > 1. Together, these results suggest the flow smoothly transitioned to a quasi-two-dimensional state in the range 0 < N < 1.

John Rhoads, Eric Edlund and Hantao Ji

2013-04-17T23:59:59.000Z

139

Effective field theory for two-species bosons in an optical lattice: Multiple order, the Nambu-Goldstone bosons, the Higgs mode and vortex lattice  

E-Print Network (OSTI)

In the previous papers, we studied the bosonic t-J mode and derived an effective field theory, which is a kind of quantum XY model. The bosonic t-J model is expected to be realized by experiments of two-component cold atoms in an optical lattice. In this paper, we consider a similar XY model that describes phase diagram of the t-J model with a mass difference. Phase diagram and critical behavior of the quantum XY model are clarified by means of the Monte-Carlo simulations. Effective field theory that describes the phase structure and low-energy excitations of the quantum XY model is derived. Nambu-Goldstone bosons and the Higgs mode are studied by using the effective field theory and interesting findings are obtained for the system with multiple order, i.e., Bose-Einstein condensations and pseudo-spin symmetry. We also investigate physical properties of the quantum XY model in an effective magnetic field that is realized by rotating the optical lattice, etc. We show that low-energy states of the system strongly depend on the strength of the "magnetic field". For some specific strength of the magnetic field, vortex lattice forms and the correlation function of the bosons exhibits solid like behavior, which is a kind of Bose-Einstein condensation.

Y. Kuno; K. Suzuki; I. Ichinose

2013-06-10T23:59:59.000Z

140

A Vortex Contactor for Carbon Dioxide Separations  

NLE Websites -- All DOE Office Websites (Extended Search)

Vortex Contactor for Carbon Dioxide Separations Vortex Contactor for Carbon Dioxide Separations Kevin T. Raterman (ratekt@inel.gov; 208-526-5444) Michael McKellar (mgq@inel.gov; 208-526-1346) Anna Podgorney (poloak@inel.gov; 208-526-0064) Douglas Stacey (stacde@inel.gov; 208-526-3938) Terry Turner (tdt@inel.gov; 208-526-8623) Idaho National Engineering and Environmental Laboratory P.O. Box 1625 Idaho Falls, Idaho 83415-2110 Brian Stokes (bxs9@pge.com; 415-972-5591) John Vranicar (jjv2@pge.com; 415-972-5591) Pacific Gas & Electric Company 123 Mission Street San Francisco, CA 94105 Introduction Many analysts 1,2,3 identify carbon dioxide (CO 2 ) capture and separation as a major roadblock in efforts to cost effectively mitigate greenhouse gas emissions via sequestration. An assessment 4 conducted by the International Energy Agency (IEA)

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Energy harvesting using vortex-induced vibrations of tensioned cables  

E-Print Network (OSTI)

The development of energy harvesting systems based on fluid/structure interactions is part of the global search for innovative tools to produce renewable energy. In this paper, the possibility to harvest energy from a flow using vortex-induced vibrations (VIV) of a tensioned flexible cable is analyzed. The fluid loading on the vibrating solid and resulting dynamics are computed using an appropriate wake-oscillator model, allowing one to perform a systematic parametric study of the efficiency. The generic case of an elastically-mounted rigid cylinder is first investigated, before considering an infinite cable with two different types of energy harvesting : a uniformly spanwise distributed harvesting and then a periodic distribution of discrete harvesting devices. The maximum harvesting efficiency is of the same order for each configuration and is always reached when the solid body and its wake are in a frequency lock-in state.

Grouthier, Clement; de Langre, Emmanuel

2012-01-01T23:59:59.000Z

142

Vortex formation during rf heating of plasma  

SciTech Connect

Experiments on a test plasma show that the linear theory of waveguide coupling to slow plasma waves begins to break down if the rf power flux exceeds approx. 30 W/cm/sup 2/. Probe measurements reveal that within 30 ..mu..s an undulation appears in the surface plasma near the mouth of the twin waveguide. This surface readjustment is part of a vortex, or off-center convective cell, driven by asymmetric rf heating of the plasma column.

Motley, R.W.

1980-05-01T23:59:59.000Z

143

Vortex flow visualization using tetrahedral cell subdivision  

Science Conference Proceedings (OSTI)

Proposes an effective technique for searching for critical points, which are points at which the velocity vector is zero. The previous method, using tetrahedral-cell subdivision, often generates multiple critical points in a hexahedral cell, and this ... Keywords: Newton's method, critical point searching technique, hexahedral cell, linear interpolation function, multiple critical points, numerical integration scheme, precise position calculation, tetrahedral cell subdivision, trilinear interpolation function, velocity vector, vortex flow visualization, vortices

A. Doi; S. Suzuki; K. Koyamada; S. Sannakanishi

1997-10-01T23:59:59.000Z

144

Neutron-Diffraction Evidence for the Ferrimagnetic Ground State of a Molecule-Based Magnet with Weakly Coupled Sublattices  

SciTech Connect

The diruthenium compound [Ru2(O2CMe)4]3[Cr(CN)6] contains two weakly coupled, ferrimag- netically ordered sublattices occupying the same volume. The magnetic field Hc 800 Oe required to align the two sublattice moments is proportional to the antiferromagnetic dipolar interaction Kc B Hc 5 10 3 meV between sublattices. Powder neutron-diffraction measurements on a deuterated sample reveal that the sublattice moments are restricted by the anisotropy of the diruthenium paddle-wheel complexes to the cubic diagonals. Those measurements also suggest that the quantum corrections to the ground state are significant.

Fishman, Randy Scott [ORNL; Campo, Javier [University of Zaragoza, Spain; Vos, Thomas E. [University of Utah; Miller, Joel S. [University of Utah

2012-01-01T23:59:59.000Z

145

QCD String as Vortex String in Seiberg-Dual Theory  

E-Print Network (OSTI)

We construct a classical vortex string solution in a Seiberg-dual theory of N=1 supersymmetric SO(N_c) QCD which flows to a confining phase. We claim that this vortex string is a QCD string, as previouly argued by M.Strassler. In SO(N_c) QCD, it is known that stable QCD strings exist even in the presence of dynamical quarks. We show that our vortex strings are stable in the Seiberg-dual theory.

Eto, Minoru; Terashima, Seiji

2007-01-01T23:59:59.000Z

146

A high transmission analyzing magnet for intense high charge state beams  

DOE Green Energy (OSTI)

The low energy beam transport (LEBT) for VENUS will provide for extraction, mass analysis and transport to the axial injection line for the 88-Inch Cyclotron. The new LEBT was designed from the beginning to handle high intensity beams where space charge forces strongly affect the transmission. The magnet has a unique design with specially shaped poles to apply sextupole correction in both the horizontal and vertical plane.

Leitner, M.; Abbott, S.R.; Leitner, D.; Lyneis, C.

2002-06-11T23:59:59.000Z

147

Nanoscale strain-induced pair suppression as a vortex-pinning mechanism in high- temperature superconductors  

SciTech Connect

Boosting large-scale superconductor applications require nanostructured conductors with artificial pinning centres immobilizing quantized vortices at high temperature and magnetic fields. Here we demonstrate a highly effective mechanism of artificial pinning centers in solution-derived high-temperature superconductor nanocomposites through generation of nanostrained regions where Cooper pair formation is suppressed. The nanostrained regions identified from transmission electron microscopy devise a very high concentration of partial dislocations associated with intergrowths generated between the randomly oriented nanodots and the epitaxial YBa{sub 2}Cu{sub 3}O{sub 7} matrix. Consequently, an outstanding vortex-pinning enhancement correlated to the nanostrain is demonstrated for four types of randomly oriented nanodot, and a unique evolution towards an isotropic vortex-pinning behaviour, even in the effective anisotropy, is achieved as the nanostrain turns isotropic. We suggest a new vortex-pinning mechanism based on the bond-contraction pairing model, where pair formation is quenched under tensile strain, forming new and effective core-pinning regions.

Llordes, Anna [ICMAB, Barcelona, Spain; Palau, A. [ICMAB, Barcelona, Spain; Gazquez, J. [Oak Ridge National Laboratory (ORNL); Coll, M. [ICMAB, Barcelona, Spain; Vlad, R. [ICMAB, Barcelona, Spain; Pomar, A. [ICMAB, Barcelona, Spain; Arbiol, Jordi [ICMAB, Barcelona, Spain; Guzman, Roger [ICMAB, Barcelona, Spain; Ye, S. [ICMAB, Barcelona, Spain; Rouco, V [ICMAB, Barcelona, Spain; Sandiumenge, Felip [ICMAB, Barcelona, Spain; Ricart, Susagna [ICMAB, Barcelona, Spain; Puig, Teresa [ICMAB, Barcelona, Spain; Varela del Arco, Maria [ORNL; Chataigner, D. [CRISMAT, Caen, France; Vanacken, J. [INPAC-Institute for Nanoscale Physics and Chemistry, Leuven, Belgium; Gutierrez, J. [INPAC-Institute for Nanoscale Physics and Chemistry, Leuven, Belgium; Moschalkov, V. [INPAC-Institute for Nanoscale Physics and Chemistry, Leuven, Belgium; Deutscher, G. [Tel Aviv University; Magen Dominguez, Cesar [ORNL; Obradors, Xavier [ICMAB, Barcelona, Spain

2012-01-01T23:59:59.000Z

148

Effect of ion mass and charge state on transport of vacuum ARC plasmas through a biased magnetic filter  

Science Conference Proceedings (OSTI)

The effect of ion mass and charge state on plasma transport through a 90{sup o}-curved magnetic filter is experimentally investigated using a pulsed cathodic arc source. Graphite, copper, and tungsten were selected as test materials. The filter was a bent copper coil biased via the voltage drop across a low-ohm, ''self-bias'' resistor. Ion transport is accomplished via a guiding electric field, whose potential forms a ''trough'' shaped by the magnetic guiding field of the filter coil. Evaluation was done by measuring the filtered ion current and determination of the particle system coefficient, which can be defined as the ratio of filter ion current, divided by the mean ion charge state, to the arc current. It was found that the ion current and particle system coefficient decreased as the mass-to-charge ratio of ions increased. This result can be qualitatively interpreted by a very simply model of ion transport that is based on compensation of the centrifugal force by the electric force associated with the guiding potential trough.

Byon, Eungsun; Kim, Jong-Kuk; Kwon, Sik-Chol; Anders, Andre

2003-12-01T23:59:59.000Z

149

Helicoidal vortex model for wind turbine aeroelastic simulation  

Science Conference Proceedings (OSTI)

The vortex method has been extended to account for blade flexibility, which is a potential source of unsteadiness in the flow past a wind turbine rotor. The code has been validated previously under the assumption of rigid blades. The aerodynamics method ... Keywords: Blade flexibility, Steady and unsteady flows, Tower interference, Vortex model

Jean-Jacques Chattot

2007-06-01T23:59:59.000Z

150

Finned Tube With Vortex Generators For A Heat Exchanger.  

DOE Patents (OSTI)

A system for and method of manufacturing a finned tube for a heat exchanger is disclosed herein. A continuous fin strip is provided with at least one pair of vortex generators. A tube is rotated and linearly displaced while the continuous fin strip with vortex generators is spirally wrapped around the tube.

Sohal, Monohar S. (Idaho Falls, ID); O' Brien, James E. (Idaho Falls, ID)

2004-09-14T23:59:59.000Z

151

Finned Tube With Vortex Generators For A Heat Exchanger.  

DOE Patents (OSTI)

A system for and method of manufacturing a finned tube for a heat exchanger is disclosed herein. A continuous fin strip is provided with at one pair of vortex generators. A tube is rotated and linearly displaced while the continuous fin strip with vortex generators is spirally wrapped around the tube.

Sohal, Manohar S. (Idaho Falls, ID); O' Brien, James E. (Idaho Falls, ID)

2005-12-20T23:59:59.000Z

152

Magnetic turbulence suppression by a helical mode in a cylindrical geometry  

Science Conference Proceedings (OSTI)

To study processes involved in a helical structure formation in reversed field pinch devices, the scaling of a turbulent boundary layer width associated with a vortex structure having large shears of magnetic field and flow is obtained for reduced magnetohydrodynamics. The coherent vortex, with its flow and magnetic shears, interacts with Alfven turbulence, forming a turbulent boundary layer at the edge of the vortex. The layer arises from the balance between turbulence diffusion rates and shearing rates and suppresses the turbulence in the structure. The suppression of turbulence impedes relaxation of the coherent vortex profiles, leading to long coherence times. The scaling of the boundary layer width reveals that both magnetic shear and flow shear can effectively suppress magnetic turbulence.

Kim, J.-H.; Terry, P. W. [Department of Physics and Center for Momentum Transport and Flow Organization, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2012-12-15T23:59:59.000Z

153

Normal-state transport in electron-doped La2-xCexCuO4 thin films in magnetic fields up to 40 Tesla  

E-Print Network (OSTI)

Normal-state transport in electron-doped La2-xCexCuO4 thin films in magnetic fields up to 40 Tesla.17 are studied in magnetic fields up to 40 Tesla. For the whole doping region investigated, the negative, the upper critical mag- netic field Bc2 order of 100 Tesla 8 is too high to be achieved. The n-type HTSCs

Moshchalkov, Victor V.

154

Stability of an optical vortex in a circular nematic cell  

SciTech Connect

The stability of an optical vortex in a cell with a circular cross section containing a nematic liquid crystal is studied. A modulation theory based on an averaged Lagrangian formulation is developed to study this stability. It is found that the vortex is stable unless the radius of the cell is very small, nearly the width of the vortex itself. Based on the analysis of a stationary vortex, the stability of a low-amplitude vortex in a large cell under the influence of its orbital angular momentum and the repelling effect of the cell boundary are studied. The predictions of this modulation theory are found to be in excellent agreement with numerical simulations.

Minzoni, Antonmaria A. [Fenomenos Nonlineales y Mecanica (FENOMEC), Departamento de Matematicas y Mecanica, Instituto de Investigacion en Matematicas Aplicadas y Sistemas, Universidad Nacional Autonoma de Mexico, 01000 Mexico D.F. (Mexico); Smyth, Noel F. [School of Mathematics and Maxwell Institute for Mathematical Sciences, University of Edinburgh, Edinburgh EH9 3JZ, Scotland (United Kingdom); Xu Zhiyong [Nonlinear Physics Center, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

2010-03-15T23:59:59.000Z

155

Stability of a fully magnetized ferromagnetic state in repulsively interacting ultracold Fermi gases  

SciTech Connect

We construct a variational wave function to study whether a fully polarized Fermi sea of ultracold atoms is energetically stable against a single spin flip. Our variational wave function contains short-range correlations at least to the same level as Gutzwiller's projected wave function. For the Hubbard lattice model and the continuum model with pure repulsive interaction, we show that a fully polarized Fermi sea is generally unstable even for infinite repulsive strength. By contrast, for a resonance model, the ferromagnetic state is possible if the s-wave scattering length is positive and sufficiently large and the system is prepared to be orthogonal to the molecular bound state. However, we cannot rule out the possibility that more exotic correlations can destabilize the ferromagnetic state.

Cui Xiaoling [Beijing National Laboratory for Condensed Matter Physics and Institute for Physics, Chinese Academy of Science, Beijing, 100190 (China); Zhai Hui [Institute for Advanced Study, Tsinghua University, Beijing, 100084 (China)

2010-04-15T23:59:59.000Z

156

Cyanide clusters of ReII with 3d metal ions and their magnetic properties: incorporating anisotropic ions into metal-cyanide clusters with high spin magnetic ground states  

E-Print Network (OSTI)

Clusters of metal ions that possess large numbers of magnetically coupled unpaired electrons have attracted much interest in recent years due to their fascinating magnetic behavior. With an appreciable component of magnetic anisotropy, these large-spin paramagnetic molecules can exhibit an energy barrier to inversion of their magnetic dipole, leading to spontaneous magnetization and magnetic hysteresis below a critical temperature. Since this behavior is a property of an individual clusters rather than a collection of molecules, this phenomenon has been dubbed ??Single Molecule Magnetism??. Our approach to the study of new high-spin systems has been to exert a measure of synthetic control in the preparation of clusters. Specifically we are employing highly anisotropic metal ions with the anticipation that these ions would engender large overall magnetic anisotropy in the resulting clusters. The first step in this process was the development of the chemistry of two new d5 ReII (S = ??) complexes, namely [ReII(triphos)(CH3CN)3][PF6]2 and [Et4N][ReII(triphos)(CN)3]. The magnetic, optical and electrochemical properties were studied and theoretical models were developed to describe the origin of the large temperature independent paramagnetism that was observed. Next, we successfully employed transition metal cyanide chemistry using the ReII building blocks to prepare a family of isostructural, cubic clusters of the general formula {[MCl]4[Re(triphos)(CN)3]4} M = Mn, Fe, Co, Ni, Cu, Zn whose 3d ions adopt local tetrahedral geometries. Within the clusters, magnetic exchange is observed between the paramagnetic ions, which has been modeled using an Ising exchange model to account for the dominating anisotropy of the ReII ion. Despite the high pseudo-symmetry of the clusters (Td), this work has yielded a rare example of a metal-cyanide single molecule magnet, {[MCl]4[Re(triphos)(CN)3]4} with an S = 8 ground state, D = -0.39 cm-1 and an effective energy barrier for magnetization reversal of Ueff = 8.8 cm-1. The elucidation of this family of isostructural clusters has also allowed us to pursue fundamental work on the structure/property relationships of the exotic, paramagnetic ReII ion. As the clusters are soluble, stable compounds, the future of this chemistry lies in the development of a true building-block approach to ??super-clusters?? that exhibit very high ground state spin values.

Schelter, Eric John

2003-05-01T23:59:59.000Z

157

Superfluid and magnetic states of an ultracold Bose gas with synthetic three-dimensional spin-orbit coupling in an optical lattice  

E-Print Network (OSTI)

We study ultracold bosonic atoms with the synthetic three-dimensional spin-orbit (SO) coupling in a cubic optical lattice. In the superfluidity phase, the lowest energy band exhibits one, two or four pairs of degenerate single-particle ground states depending on the SO-coupling strengths, which can give rise to the condensate states with spin-stripes for the weak atomic interactions. In the deep Mott-insulator regime, the effective spin Hamiltonian of the system combines three-dimensional Heisenberg exchange interactions, anisotropy interactions and Dzyaloshinskii-Moriya interactions. Based on Monte Carlo simulations, we numerically demonstrate that the resulting Hamiltonian with an additional Zeeman field has a rich phase diagram with spiral, stripe, vortex crystal, and especially Skyrmion crystal spin-textures in each xy-plane layer. The obtained Skyrmion crystals can be tunable with square and hexagonal symmetries in a columnar manner along the z axis, and moreover are stable against the inter-layer spin-spin interactions in a large parameter region.

Dan-Wei Zhang; Ji-Pei Chen; Chuan-Jia Shan; Z. D. Wang; Shi-Liang Zhu

2013-01-14T23:59:59.000Z

158

MHK Technologies/Vortex Induced Vibrations Aquatic Clean Energy VIVACE |  

Open Energy Info (EERE)

Vortex Induced Vibrations Aquatic Clean Energy VIVACE Vortex Induced Vibrations Aquatic Clean Energy VIVACE < MHK Technologies Jump to: navigation, search << Return to the MHK database homepage Vortex Induced Vibrations Aquatic Clean Energy VIVACE.jpg Technology Profile Primary Organization Vortex Hydro Energy LLC Project(s) where this technology is utilized *MHK Projects/Marine Hydrodynamics Laboratory at the University of Michigan Technology Resource Click here Current/Tidal Technology Type Click here Reciprocating Device Technology Readiness Level Click here TRL 4: Proof of Concept Technology Description The VIVACE (Vortex Induced Vibrations Aquatic Clean Energy) device is based on the extensively studied phenomenon of Vortex Induced Vibrations (VIV), which was first observed five-hundred years ago by Leonardo DaVinci in the form of 'Aeolian Tones.' VIV results from vortices forming and shedding on the downstream side of a bluff body in a current. Vortex shedding alternates from one side to the other, thereby creating a vibration or oscillation. The VIV phenomenon is non-linear, which means it can produce useful energy at high efficiency over a wide range of current speeds and directions.This converter is unlike any existing technology, as it does not use turbines, propellers, or dams. VIVACE converts the horizontal hydrokinetic energy of currents into cylinder mechanical energy. The latter is then converted to electricity through electric power generators.

159

Principles of equilibrium statistical mechanics revisited: The idea of vortex energy  

E-Print Network (OSTI)

We show that the law of energy conservation with the fact of matter stability imply the existence of energy complementary to that given by the function of states of interacting systems and treated, with the environment, the function of states of interacting extended systems. The complementary energy, we called it vortex, is integral, not quantized, and causes trends contrary to that prescribed by equilibrium statistical mechanics. We formulate its principles and theorems, and question traditional insights in thermodynamics, entropy law, phase transitions, persistent currents, Brownian motion.

V. E. Shapiro

2013-05-21T23:59:59.000Z

160

Development of tritium technology for the United States magnetic fusion energy program  

SciTech Connect

Tritium technology development for the DOE fusion program is taking place principally at three laboratories, Mound Facility, Argonne National Laboratory and the Los Alamos Scientific Laboratory. This paper will review the major aspects of each of the three programs and look at aspects of the tritium technology being developed at other laboratories within the United States. Facilities and experiments to be discussed include the Tritium Effluent Control Laboratory and the Tritium Storage and Delivery System for the Tokamak Fusion Test Reactor at Mound Facility; the Lithium Processing Test Loop and the solid breeder blanket studies at Argonne; and the Tritium Systems Test Assembly at Los Alamos.

Anderson, J.L.; Wilkes, W.R.

1980-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Vortex flow around the bases of obstacles  

E-Print Network (OSTI)

.2 The horseshoe . vortex formed by a separating turbulent boundary layer 5.3 Scour around obstacles in an erodible bed 114 116 117 . ·4 References Uf'l() I:!~oLtlecl F,'obL.efl):' Llr:cl ~u.g5el:dto/J~ fer ju.iLt(t' wc"..,I" 11 2 119 Figures (vi... , are shmm in figUre 2.3.4. It can be seen that there is a rather high le,el of turbulence in the tunnel free stream. This is poss:l.bly due to the extra screens placed upstream of the \\'lorking section. At the higher speeds used this turbulence...

Baker, Christopher James

1979-02-06T23:59:59.000Z

162

The multiple vortex nature of tropical cyclogenesis  

E-Print Network (OSTI)

This thesis contains an observational analysis of the genesis of Tropical Storm Allison (2001). Using a paradigm of tropical cyclone formation as the superposition of potential vorticity (PV) anomalies, the importance of different scales of PV merger to various aspects of Allison?s formation is discussed. While only the case of Allison is discussed in great detail, other studies have also documented PV superposition on various scales, and superposition could be important for most tropical cyclones. Preceding Allison?s genesis, PV superposition on the large scale destabilized the atmosphere and increased low-level cyclonic vorticity. This presented a more favorable environment for the formation of MCV-type PV anomalies and smaller, surface-based, meso-?-scale vortices. Although these vortices eventually merged to form a more concentrated vortex with stronger surface pressure gradients, the merger happened well after landfall of Allison and no strengthening ensued. The unstable, vorticity-rich environment was also favorable for the development of even smaller, meso-?-scale vortices that accompanied deep convective cells within one of Allison?s meso-?-scale vortices. The observations herein suggest that the meso-?- scale convective cells and vortices are the respective source of PV production and building blocks for the meso-?-scale vortices. Finally, this thesis discusses issues related to the multiple vortex nature of tropical cyclone formation. For instance, the tracking of developing tropical cyclones is greatly complicated by the presence of multiple vortices. For these cases, the paradigm of a single cyclone center is inappropriate and alternative tracking methods are introduced.

Sippel, Jason Allen

2004-12-01T23:59:59.000Z

163

State  

U.S. Energy Information Administration (EIA) Indexed Site

Biodiesel Producers and Production Capacity by State, September 2013 Biodiesel Producers and Production Capacity by State, September 2013 State Number of Producers Annual Production Capacity (million gallons per year) Alabama 3 47 Alaska - - Arizona 1 2 Arkansas 3 85 California

164

MHK Technologies/SeaUrchin Vortex Reaction Turbine | Open Energy  

Open Energy Info (EERE)

SeaUrchin Vortex Reaction Turbine SeaUrchin Vortex Reaction Turbine < MHK Technologies Jump to: navigation, search << Return to the MHK database homepage SeaUrchin Vortex Reaction Turbine.jpg Technology Profile Primary Organization Elemental Energy Technologies Limited ABN 46 128 491 903 Technology Resource Click here Current Technology Type Click here Axial Flow Turbine Technology Readiness Level Click here TRL 4 Proof of Concept Technology Description A revolutionary vortex reaction turbine branded the SeaUrchin an advanced third generation marine turbine technology capable of delivering inexpensive small to large scale baseload or predictable electricity by harnessing the kinetic energy of free flowing ocean currents tides and rivers Technology Dimensions Device Testing Date Submitted 55:15.2

165

Inertia–Gravity Waves Generated within a Dipole Vortex  

Science Conference Proceedings (OSTI)

Vortex dipoles provide a simple representation of localized atmospheric jets. Numerical simulations of a synoptic-scale dipole in surface potential temperature are considered in a rotating, stratified fluid with approximately uniform potential ...

Chris Snyder; David J. Muraki; Riwal Plougonven; Fuqing Zhang

2007-12-01T23:59:59.000Z

166

Ozone Chemistry during the 2002 Antarctic Vortex Split  

Science Conference Proceedings (OSTI)

In September 2002, the Antarctic polar vortex was disturbed, and it split into two parts caused by an unusually early stratospheric major warming. This study discusses the chemical consequences of this event using the Chemical Lagrangian Model of ...

Jens-Uwe Grooß; Paul Konopka; Rolf Müller

2005-03-01T23:59:59.000Z

167

Linear Dynamics of the Multiple-Vortex Phenomenon in Tornadoes  

Science Conference Proceedings (OSTI)

The reason for existence of two separate unstable modes, previously described by Gall for flows in vortex simulators, is explored. When the energy equation for an unstable disturbance is considered, it is clear that the most unstable wave must be ...

Robert L. Gall

1985-04-01T23:59:59.000Z

168

Baroclinic Transition of a Long-Lived Mesoscale Convective Vortex  

Science Conference Proceedings (OSTI)

The period 5–15 June 2003, during the field phase of the Bow Echo and Mesoscale Convective Vortex (MCV) Experiment (BAMEX), was noteworthy for the wide variety of mesoscale convective systems (MCSs) that occurred. Of particular interest was a ...

Thomas J. Galarneau Jr.; Lance F. Bosart; Christopher A. Davis; Ron McTaggart-Cowan

2009-02-01T23:59:59.000Z

169

Reexamining the Vertical Development of Tornadic Vortex Signatures in Supercells  

Science Conference Proceedings (OSTI)

Observations from a hybrid phased-array Doppler radar, the Mobile Weather Radar, 2005 X-band, Phased-Array (MWR-05XP), were used to investigate the vertical development of tornadic vortex signatures (TVSs) during supercell tornadogenesis. Data ...

Michael M. French; Howard B. Bluestein; Ivan PopStefanija; Chad A. Baldi; Robert T. Bluth

170

Assimilating Vortex Position with an Ensemble Kalman Filter  

Science Conference Proceedings (OSTI)

Observations of hurricane position, which in practice might be available from satellite or radar imagery, can be easily assimilated with an ensemble Kalman filter (EnKF) given an operator that computes the position of the vortex in the background ...

Yongsheng Chen; Chris Snyder

2007-05-01T23:59:59.000Z

171

Spontaneous Imbalance and Hybrid Vortex–Gravity Structures  

Science Conference Proceedings (OSTI)

After reviewing the background, this article discusses the recently discovered examples of hybrid propagating structures consisting of vortex dipoles and comoving gravity waves undergoing wave capture. It is shown how these examples fall outside ...

Michael E. McIntyre

2009-05-01T23:59:59.000Z

172

Some Aspects of Vortex Structure Related to Tropical Cyclone Motion  

Science Conference Proceedings (OSTI)

Some effect of tropical cyclone structure on the vortex motion are examined in a nondivergent, barotropic numerical model with no basic current. As suggested earlier by DeMaria, the initial maximum wind speed has little effect on the track. ...

Michael Fiorino; Russell L. Elsberry

1989-04-01T23:59:59.000Z

173

state  

Science Conference Proceedings (OSTI)

NIST. state. (definition). Definition: The condition of a finite state machine or Turing machine at a certain time. Informally, the content of memory. ...

2013-11-08T23:59:59.000Z

174

Closed cycle steam turbine system with liquid vortex pump  

SciTech Connect

A closed cycle steam generating system is described comprising a steam boiler, and a steam turbine includes a vacuum pump of the liquid vortex type for condensing the exhaust steam from the turbine, a feedwater pump being employed for returning the condensate to the boiler. The tank of the vortex pump is maintained filled with water and the pressure in the tank is regulated automatically to maintain a predetermined value thereof.

Brown, K.D.

1976-08-10T23:59:59.000Z

175

Nonclassicality of vortex Airy beams in the Wigner representation  

Science Conference Proceedings (OSTI)

The Wigner distribution function (WDF) of a vortex Airy beam is calculated analytically. The WDF provides intuitive pictures of the intriguing features of vorticity in phase space. The nonclassical property of the vortex Airy beam and the Airy beam is analyzed through the negative parts of the WDF. The study shows that destructive interference of certain classical waves can mimic nonclassical lights such as those due to quantum effects.

Chen Ruipin [School of Sciences, Zhejiang A and F University, Lin'an, Zhejiang Province 311300 (China); Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ooi, C. H. Raymond [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2011-10-15T23:59:59.000Z

176

Depinning of a superfluid vortex line by Kelvin waves  

E-Print Network (OSTI)

We measure the interaction of a single superfluid vortex with surface irregularities. While vortex pinning in superconductors usually becomes weaker at higher temperatures, we find the opposite behavior. The pinning steadily increases throughout our measurement range, from 0.15Tc to over 0.5Tc. We also find that moving the other end of the vortex decreases the pinning, so we propose Kelvin waves along the vortex as a depinning mechanism. PACS numbers: 67.40.Vs, 74.60.Ge Pinning sites can trap vortices in a variety of systems. In superconductors, where vortex motion leads to nonzero resistance, a vast amount of work has been devoted to preventing such motion by introducing defects. Experimental work has shown that defects comparable in size to the vortex core make effective pin centers, and that straight [1] or splayed [2] line defects can increase the pin strength. Yet the mechanisms by which vortices interact with pin sites remain unresolved. Experimentally, pinning in superconductors becomes weaker as

L. A. K. Donev; L. Hough; R. J. Zieve

2001-01-01T23:59:59.000Z

177

State  

Science Conference Proceedings (OSTI)

State NIST. Weights and Measures. Laboratories. Program Handbook. NIST Handbook 143. March 2003. Preface. The National ...

2010-11-30T23:59:59.000Z

178

Magnetic soft x-ray microscopy-imaging fast spin dynamics inmagnetic nanostructures  

SciTech Connect

Magnetic soft X-ray microscopy combines 15nm spatial resolution with 70ps time resolution and elemental sensitivity. Fresnel zone plates are used as X-ray optics and X-ray magnetic circular dichroism serves as magnetic contrast mechanism. Thus scientifically interesting and technologically relevant low dimensional nanomagnetic systems can be imaged at fundamental length and ultrafast time scales in a unique way. Studies include magnetization reversal in magnetic multilayers, nanopatterned systems, vortex dynamics in nanoelements and spin current induced phenomena.

Fischer, Peter; Kim, Dong-Hyun; Mesler, Brooke L.; Chao, Weilun; Sakdinawat, Anne E.; Anderson, Erik H.

2007-06-01T23:59:59.000Z

179

Magnetic Thin Films and Devices  

Science Conference Proceedings (OSTI)

... metal atoms that form small magnets with Curie ... a toggle operation of the magnetic state of ... A high-frequency probe driving a microwave waveguide ...

2010-10-05T23:59:59.000Z

180

Nanoscale strain-induced pair suppression as a source of vortex pinning in high-temperature superconductors  

SciTech Connect

Boosting large-scale superconductor applications require nanostructured conductors with artificial pinning centres immobilizing quantized vortices at high temperature and magnetic fields. Here we demonstrate a highly effective mechanism of artificial pinning centres in solution-derived high-temperature superconductor nanocomposites through generation of nanostrained regions where Cooper pair formation is suppressed. The nanostrained regions identified from transmission electron microscopy devise a very high concentration of partial dislocations associated with intergrowths generated between the randomly oriented nanodots and the epitaxial YBa{sub 2}Cu{sub 3}O{sub 7} matrix. Consequently, an outstanding vortex-pinning enhancement correlated to the nanostrain is demonstrated for four types of randomly oriented nanodot, and a unique evolution towards an isotropic vortex-pinning behaviour, even in the effective anisotropy, is achieved as the nanostrain turns isotropic. We suggest a new vortex-pinning mechanism based on the bond-contraction pairing model, where pair formation is quenched under tensile strain, forming new and effective core-pinning regions.

Llordes, A. [ICMAB, Barcelona, Spain; Palau, A. [ICMAB, Barcelona, Spain; Vlad, R. [ICMAB, Barcelona, Spain; Pomar, A. [ICMAB, Barcelona, Spain; Arbiol, Jordi [ICMAB, Barcelona, Spain; Guzman, Roger [ICMAB, Barcelona, Spain; Gazquez Alabart, Jaume [ORNL; Varela del Arco, Maria [ORNL; Sandiumenge, Felip [ICMAB, Barcelona, Spain; Ricart, Susagna [ICMAB, Barcelona, Spain; Puig, Teresa [ICMAB, Barcelona, Spain; Chataigner, D. [CRISMAT, Caen, France; Vanacken, J. [INPAC-Institute for Nanoscale Physics and Chemistry, Leuven, Belgium; Gutierrez, J. [INPAC-Institute for Nanoscale Physics and Chemistry, Leuven, Belgium; Deutscher, G. [Tel Aviv University; Moschalkov, V. [INPAC-Institute for Nanoscale Physics and Chemistry, Leuven, Belgium; Obradors, Xavier [ICMAB, Barcelona, Spain

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Stratospheric Sudden Warmings as Self-Tuning Resonances. Part I: Vortex Splitting Events  

Science Conference Proceedings (OSTI)

The fundamental dynamics of “vortex splitting” stratospheric sudden warmings (SSWs), which are known to be predominantly barotropic in nature, are reexamined using an idealized single-layer f-plane model of the polar vortex. The aim is to ...

N. Joss Matthewman; J. G. Esler

2011-11-01T23:59:59.000Z

182

A Theory for Mixed Vortex Rossby–Gravity Waves in Tropical Cyclones  

Science Conference Proceedings (OSTI)

Vortex–Rossby waves (VRWs) and inertial gravity waves (IGWs) have been proposed to explain the propagation of spiral rainbands and the development of dynamical instability in tropical cyclones (TCs). In this study, a theory for mixed vortex–...

Wei Zhong; Da-Lin Zhang; Han-Cheng Lu

2009-11-01T23:59:59.000Z

183

Influence of a Strong Bottom Slope on the Evolution of a Surface-Intensified Vortex  

Science Conference Proceedings (OSTI)

The authors investigate the influence of steep bottom topography on the propagation of a vortex in a two-layer quasigeostrophic model. The vortex is intensified in the upper layer and the planetary beta effect is taken into account.

Virginie Thierry; Yves Morel

1999-05-01T23:59:59.000Z

184

Generation and Propagation of Inertia–Gravity Waves from Vortex Dipoles and Jets  

Science Conference Proceedings (OSTI)

This study investigates gravity wave generation and propagation from jets within idealized vortex dipoles using a nonhydrostatic mesoscale model. Two types of initially balanced and localized jets induced by vortex dipoles are examined here. ...

Shuguang Wang; Fuqing Zhang; Chris Snyder

2009-05-01T23:59:59.000Z

185

Barotropic Simulation of Large-Scale Mixing in the Antarctic Polar Vortex  

Science Conference Proceedings (OSTI)

Theory and observations suggest that the Antarctic polar vortex is relatively isolated from midlatitudes, although others have interpreted the observations to indicate that there is substantial mixing from the interior of the vortex into middle ...

Kenneth P. Bowman

1993-09-01T23:59:59.000Z

186

Vortex dynamics : a window into the properties of type-II superconductors  

E-Print Network (OSTI)

DIEGO Vortex Dynamics: A Window Into the Properties of Type-DISSERTATION Vortex Dynamics: A Window Into the Propertiesa ?lm deposits on the window through which the laser beam

Taylor, Benjamin Jeremy

2006-01-01T23:59:59.000Z

187

Combining the vortex-in-cell and parallel fast multipole methods for efficient domain decomposition simulations  

Science Conference Proceedings (OSTI)

A new combination of vortex-in-cell and parallel fast multipole methods is presented which allows to efficiently simulate, in parallel, unbounded and half-unbounded vortical flows (flows with one flat wall). In the classical vortex-in-cell (VIC) method, ... Keywords: Incompressible flows, Lagrangian methods, Parallel fast multipole method, Particle methods, Unbounded flows, Unsteady flows, Vortex methods, Vortex-in-cell method, Wall-bounded flows

Roger Cocle; Grégoire Winckelmans; Goéric Daeninck

2008-02-01T23:59:59.000Z

188

The Data Vortex, an All Optical Path Multicomputer Interconnection Network  

E-Print Network (OSTI)

All optical path interconnection networks employing dense wavelength division multiplexing can provide vast improvements in supercomputer performance. However, the lack of efficient optical buffering requires investigation of new topologies and routing techniques. This paper introduces and evaluates the Data Vortex optical switching architecture which uses cylindrical routing paths as a packet buffering alternative. In addition, the impact of the number of angles on the overall network performance is studied through simulation. Using optimal topology configurations, the Data Vortex is compared to two existing switching architectures—butterfly and omega networks. The three networks are compared in terms of throughput, accepted traffic ratio, and average packet latency. The Data Vortex is shown to exhibit comparable latency and a higher acceptance rate (2x at 50 percent load) than the butterfly and omega topologies.

Cory Hawkins; Benjamin A. Small; D. Scott Wills; Keren Bergman

2007-01-01T23:59:59.000Z

189

Low Head, Vortex Induced Vibrations River Energy Converter  

DOE Green Energy (OSTI)

Vortex Induced Vibrations Aquatic Clean Energy (VIVACE) is a novel, demonstrated approach to extracting energy from water currents. This invention is based on a phenomenon called Vortex Induced Vibrations (VIV), which was first observed by Leonardo da Vinci in 1504AD. He called it ‘Aeolian Tones.’ For decades, engineers have attempted to prevent this type of vibration from damaging structures, such as offshore platforms, nuclear fuel rods, cables, buildings, and bridges. The underlying concept of the VIVACE Converter is the following: Strengthen rather than spoil vortex shedding; enhance rather than suppress VIV; harness rather than mitigate VIV energy. By maximizing and utilizing this unique phenomenon, VIVACE takes this “problem” and successfully transforms it into a valuable resource for mankind.

Bernitsas, Michael B.; Dritz, Tad

2006-06-30T23:59:59.000Z

190

Shock-compressible-vortex interactions: Computing approximate post-shock fields  

E-Print Network (OSTI)

Shock-compressible-vortex interactions: Computing approximate post-shock fields G.K. O'Reilly and D of the passage of a planar shock through a steady compressible vortex is developed. To compute the approximate post-shock fields, the steady pre-shock vortex is decomposed into a sum of frozen sinusoidal modes

Barr, Al

191

Non-Contact Haptic Feedback Using Air Vortex Rings Sidhant Gupta1,2  

E-Print Network (OSTI)

regions of the human body. Author Keywords Non-contact haptic feedback; air vortex rings ACM1 AirWave: Non-Contact Haptic Feedback Using Air Vortex Rings Sidhant Gupta1,2 , Dan Morris1 feedback into such interaction. In this work, we explore the use of air vortex rings for this purpose

Rajamani, Sriram K.

192

Blade-Vortex Interactions in High Pressure Steam Turbines  

E-Print Network (OSTI)

A detailed experimental and numerical investigation of the transport of streamwise (passage) vortices in high-pressure axial turbines and their interaction with the downstream blade rows was performed. The results indicate large variations in the downstream flow field, notably the development of the secondary flows. The mechanism of passage vortex transport was studied in two differently configured high-pressure turbine stages. In the first configuration, the blades are radially stacked while the second configuration features three-dimensionally stacked high-pressure steam turbine blading. The stator hub passage vortex is chopped by the downstream blade row in a similar way to the wake. The bowed vortex tube near the inlet to the rotor appeared to develop two counter-rotating legs extending back to the leading edges of the adjacent blades. These were termed the suction side leg and the pressure side leg. The two legs of the incoming passage vortex then convect with the respective velocities on the blade surfaces. The results are discussed for the radially stacked turbine and the 3-D turbine separately.

Venkata Siva Prasad Chaluvadi

2000-01-01T23:59:59.000Z

193

On the Onset Vortex of the Summer Monsoon  

Science Conference Proceedings (OSTI)

In this paper we examine the evolution of the low-level flow over the Arabian Sea during the onset of the summer monsoon. A detailed examination of the onset vortex that forms over the Arabian Sea just prior to the commencement of heavy rains ...

T. N. Krishnamurti; Philip Ardanuy; Y. Ramanathan; Richard Pasch

1981-02-01T23:59:59.000Z

194

Electronic Structure Theory of the Ground State and Photoemission Spectra of Non-Magnetic {delta}-Pu, fcc-Am, and Pu-Am Alloys  

Science Conference Proceedings (OSTI)

The around-the-mean-field version of the LDA+U correlated band theory is applied to investigate the electronic and magnetic structure of d-Pu, Am, their alloys and compounds. It gives correct non-magnetic ground state for Pu and Am, and provides a good agreement with experimental equilibrium volumes and bulk moduli. For Pu-Am alloys, despite a lattice expansion caused by the Am atoms, neither tendency to 5f localization nor formation of local magnetic moments on Pu atoms in Pu-Am alloys are found. In order to access the experimental photoelectron spectra, we developed a straightforward and efficient procedure to perform dynamical mean-field (DMFT) calculations on the top of the static mean-field LDA+U approximation. Starting from self-consistent LDA+U ground state we included multiplet transitions using the Hubbard-I approximation. We obtained fairly good agreement with experimental photoelectron spectra of {delta}-Pu, Am, Pu0.25Am0.75 alloy, PuTe, and AmX (X=N,Sb). Our calculations show the importance of electron correlations beyond those which are included in conventional (LDA/GGA) band theory for Pu and Am based systems. Furthermore, we have shown that the three narrow features observed in the valence band spectra of Pu and majority of Pu compounds can be identified with the most intense atomic excitations (multiplets). The calculations explain that the atomic-like excitations can be observed even if the 5f states are not fully localized as in {delta}-Pu, and the atomic character fixes the characteristic energies such that similar features are found in spectra of diverse Pu systems. (authors)

Shick, Alexander; Drchal, Vaclav [Condensed Matter Theory, Institute of Physics, Academy of Sciences of Czech Republic, Prague (Czech Republic); Havela, Ladislav [Charles University, CS-121 16 Prague (Czech Republic); Kolorenc, Jindrich [Condensed Matter Theory, Institute of Physics, Academy of Sciences of Czech Republic, Prague (Czech Republic)]|[Department of Physics, North Carolina State University, Raleigh, North Carolina (United States)

2007-07-01T23:59:59.000Z

195

Study of hydrogen in coals, polymers, oxides, and muscle water by nuclear magnetic resonance; extension of solid-state high-resolution techniques. [Hydrogen molybdenum bronze  

DOE Green Energy (OSTI)

Nuclear magnetic resonance (NMR) spectroscopy has been an important analytical and physical research tool for several decades. One area of NMR which has undergone considerable development in recent years is high resolution NMR of solids. In particular, high resolution solid state /sup 13/C NMR spectra exhibiting features similar to those observed in liquids are currently achievable using sophisticated pulse techniques. The work described in this thesis develops analogous methods for high resolution /sup 1/H NMR of rigid solids. Applications include characterization of hydrogen aromaticities in fossil fuels, and studies of hydrogen in oxides and bound water in muscle.

Ryan, L.M.

1981-10-01T23:59:59.000Z

196

Engineering Nanocolumnar Defect Configurations for Optimized Vortex Pinning in High Temperature Superconducting Nanocomposite Wires  

SciTech Connect

High temperature superconducting (HTS), coated conductor wires based on nanocomposite films containing self-assembled, insulating BaZrO3 (BZO) nanocolumnar defects have previously been reported to exhibit enhanced vortex pinning. Here, we report on microstructural design via control of BZO nanocolumns density in YBa2Cu3O7- (YBCO)+BZO nancomposite films to achieve the highest critical current density, Jc(H, ,T). X-ray diffraction and microstructural examination shows increasing number density of epitaxial BZO nanocolumns in the highly cube-textured YBCO matrix with increasing nominal BZO additions. Transport property measurement reveals that an increase in BZO content upto 4 vol% is required to sustain the highest pinning and Jc performance as the magnetic field increases. By growing thicker, single-layer nanocomposite films (~4 m) with controlled density of BZO columnar defects, the critical current (Ic) of ~1000 A/cm at 77 K, self-field and the minimum Ic of 455 A/cm at 65 K and 3 T for all magnetic field orientations were obtained. This is the highest Ic reported to date for films on metallic templates which are the basis for the 2nd generation, coated conductor-based HTS wires.

Wee, Sung Hun [ORNL; Zuev, Yuri L [ORNL; Cantoni, Claudia [ORNL; Goyal, Amit [ORNL; Ahuja, Raj [Waukesha Electric Systems Inc.; Abiade, J. [North Carolina A& T State University

2013-01-01T23:59:59.000Z

197

Minimum Magnetic Energy Theorem  

E-Print Network (OSTI)

The Thomson's Theorem states that static charge distributions in conductors show up at the conducting surfaces in an equipotential configuration, so that the electrostatic energy is a minimum. In this work we study an analogue statement for magnetic systems: in a given set of conductors, the stored magnetic field energy reaches the minimum value for superficial current distributions so that the magnetic vector potential is tangent to the conductors surfaces. This is the counterpart of Thomson's theorem for the magnetic field.

Fiolhais, M C N

2008-01-01T23:59:59.000Z

198

MHK Technologies/Vortex Oscillation | Open Energy Information  

Open Energy Info (EERE)

Oscillation Oscillation < MHK Technologies Jump to: navigation, search << Return to the MHK database homepage Vortex Oscillation.jpg Technology Profile Primary Organization Vortex Oscillation Technology Ltd Technology Resource Click here Current Technology Type Click here Attenuator Technology Readiness Level Click here TRL 1 3 Discovery Concept Def Early Stage Dev Design Engineering Technology Description If cylinder or another body is fixed on a moving bonding this force can set the body or its separate parts into oscillation e g elastic slat If the system of mechanical energy output is organized correctly this device can be considered as generator Technology Dimensions Device Testing Date Submitted 08:12.7 << Return to the MHK database homepage Retrieved from

199

Hairpin vortex formation, a case study for unsteady visualization.  

SciTech Connect

To better understand the vortex dynamics of coherent structures in turbulent and transitional boundary layers, we consider direct numerical simulation of the interaction between a flat-plateboundary-layer flow and an isolated hemispherical roughness element. Of principal interest is the evolution of hairpin vortices that form an interlacing pattern in the wake of the hemisphere, lift away from the wall, and are stretched by the shearing action of the boundary layer. Using animations of unsteady three-dimensional representations of this flow, produced by the vtk toolkit and enhanced to operate in a CAVE virtual environment, we identify and study several key features in the evolution of this complex vortex topology not previously observed in other visualization formats.

Fischer, P. F.; Papka, M. E.; Szymanski, M.; Tufo, H. M.

1999-08-10T23:59:59.000Z

200

Microscopic evidence for a partially gapped density wave state in {alpha}-(BEDT-TTF){sub 2}KHg(SCN){sub 4} in high magnetic fields.  

Science Conference Proceedings (OSTI)

We present NMR measurements on {alpha}-(BEDt-TTF){sub 2}KHg(SCN){sub 4}, in which the six inner carbon sites of BEDT-TTF are labeled with the {sup 13}C isotope, at low temperatures and in magnetic fields up to 28.8 T. We find, based on microscopic measurements which probe the center of the primary molecular orbital, that the density wave ground state of this system persists up to fields well above the so-called 'kink field', a hysteretic transition observed in transport near 23 T below 6 K. The main implication of this result is that in the low temperature limit, the ground state of this material is not fully metallic, but still partially gapped, even to 28.8 T. We obtain a BCS-like relationship between the transition temperature and the energy gap, as derived from the spin relaxation measurements using a simple model. Further, the {sup 13}C NMR spectrum is relatively insensitive to crossing the phase boundary, a result that does not support the notion that the ground state is a conventional spin density wave ground state.

Kuhns, P. L.; Brooks, J. S.; Caldwell, T.; Moulton, W. G.; Reyes, A. P.; Biskup, N.; Kini, A. M.; Schlueter, J. A.; Wang, H. H.; Geiser, U.; Williams, J. M.; Florida State Univ.

1999-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Synoptic-scale nonlinear stationary magnetized Rossby waves in the ionospheric E-layer  

Science Conference Proceedings (OSTI)

Magnetized Rossby waves are produced by a dynamo electric field and represent the ionospheric generalization of tropospheric Rossby waves in a rotating atmosphere with a spatially inhomogeneous geomagnetic field. They are described by the modified Charney-Obukhov equation with a Poisson-bracket convective nonlinearity. This type of equation has solutions in the form of synoptic-scale nonlinear solitary dipole vortex structures of 1000-3000 km in diameter. With the use of equivalence conditions, various stationary nonlinear solutions are obtained and investigated analytically. The basic characteristics of stationary vortex structures for magnetized Rossby waves are investigate000.

Kaladze, T. D. [Tbilisi State University, I. Vekua Institute of Applied Mathematics (Georgia); Horton, W. [University of Texas at Austin, Institute for Fusion Studies (United States)

2006-12-15T23:59:59.000Z

202

Observable Vortex Properties in Finite Temperature Bose Gases  

E-Print Network (OSTI)

We study the dynamics of vortices in finite temperature atomic Bose-Einstein condensates, focussing on decay rates, precession frequencies and core brightness, motivated by a recent experiment (Freilich et al. Science 329, 1182 (2010)) in which real-time dynamics of a single vortex was observed. Using the ZNG formalism based on a dissipative Gross-Pitaevskii equation for the condensate coupled to a semi-classical Boltzmann equation for the thermal cloud, we find a rapid nonlinear increase of both the decay rate and precession frequency with increasing temperatures. The increase, which is dominated by the dynamical condensate-thermal coupling is also dependent on the intrinsic thermal cloud collisional dynamics; the precession frequency also varies with the initial radial coordinate. The integrated thermal cloud density in the vortex core is for the most part independent of the position of the vortex (except when it is near the condensate edge) with its value increasing with temperature. This could potentially be used as a variant to the method of Coddington et al. (Phys. Rev. A 70, 063607 (2004)) for experimentally determining the temperature.

A. J. Allen; E. Zaremba; C. F. Barenghi; N. P. Proukakis

2012-10-30T23:59:59.000Z

203

DETECTION OF NONPOLAR IONS IN {sup 2}{Pi}{sub 3/2} STATES BY RADIOASTRONOMY VIA MAGNETIC DIPOLE TRANSITIONS  

Science Conference Proceedings (OSTI)

The possibility of magnetic dipole-induced pure rotational transitions in the interstellar medium is investi- gated for symmetric Hund's case (a) linear molecules, such as H-C{identical_to}C-H{sup +} (X-tilde {sup 2}{Pi}{sub 3/2u}), CO{sub 2} {sup +} (X-tilde {sup 2}{Pi}{sub 3/2g}), H-C{identical_to}C-C{identical_to}C-H{sup +} (X-tilde {sup 2}{Pi}{sub 3/2g}), and N{sub 3} (X-tilde {sup 2}{Pi}{sub 3/2g}). These species lack an electric dipole moment and therefore cannot undergo pure rotational electric dipole transitions. These species can undergo pure rotational transitions via the parallel component of the magnetic dipole operator, however. The transition moments and Einstein A coefficients for the allowed pure rotational transitions are derived for a general Hund's case (a) linear molecule, and tabulated for the examples of H-C{identical_to}C-H{sup +} ({sup 2}{Pi}{sub 3/2u}) and H-C{identical_to}C-C{identical_to}C-H{sup +} ({sup 2}{Pi}{sub 3/2g}). It is found that the rates of emission are comparable to collision rates in interstellar clouds, suggesting that this decay mechanism may be important in simulating rotational population distributions in diffuse clouds and for detecting these molecules by radioastronomy. Expected line positions for the magnetic dipole-allowed R{sub ef} (J) and R{sub fe} (J) transitions of H-C{identical_to}C-H{sup +} ({sup 2}{Pi}{sub 3/2u}), H-C{identical_to}C-C{identical_to}C-H{sup +} ({sup 2}{Pi}{sub 3/2g}), CO{sub 2}{sup +} ({sup 2}{Pi}{sub 3/2g}), and N{sub 3} ({sup 2}{Pi}{sub 3/2g}) are tabulated to assist in their observation by radioastronomy or in the laboratory.

Morse, Michael D. [Department of Chemistry, University of Utah, Salt Lake City, UT 84112 (United States); Maier, John P., E-mail: morse@chem.utah.edu, E-mail: j.p.maier@unibas.ch [Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland)

2011-05-10T23:59:59.000Z

204

Numerical Simulation of Flame-Vortex Interactions in Natural and Synthetic Gas Mixtures .  

E-Print Network (OSTI)

??The interactions between laminar premixed flames and counter-rotating vortex pairs in natural and synthetic gas mixtures have been computationally investigated through the use of Direct… (more)

Weiler, Justin D.

2004-01-01T23:59:59.000Z

205

Vortex formation of a Bose-Einstein condensate in a rotating deep optical lattice  

Science Conference Proceedings (OSTI)

We study the dynamics of vortex nucleation and lattice formation in a Bose-Einstein condensate in a rotating square optical lattice by numerical simulations of the Gross-Pitaevskii equation. Different dynamical regimes of vortex nucleation are found, depending on the depth and period of the optical lattice. We make an extensive comparison with the experiments by R. A. Williams et al.[Phys. Rev. Lett. 104, 050404 (2010)], especially focusing on the issues of the critical rotation frequency for the first vortex nucleation and the vortex number as a function of rotation frequency.

Kato, Akira; Nakano, Yuki; Kasamatsu, Kenichi; Matsui, Tetsuo [Department of Physics, Kinki University, Higashi-Osaka, Osaka 577-8502 (Japan)

2011-11-15T23:59:59.000Z

206

Annihilation of vortex dipole in an Oblate Bose-Einstein Condensate  

E-Print Network (OSTI)

We theoretically explore the annihilation of vortex dipole, generated when an obstacle moves through a condensate, in an oblate Bose-Einstein Condensate and the possible reasons for the annihilation. We show that the grey soliton, which results from vortex dipole annihilation, is lower in energy than the vortex dipole. We also investigate the annihilation events numerically and observe annihilation occurs only when the vortex dipole overtake the obstacle. Further more, we find that the adding noise reduces the probability of annihilation events. This may explain the lack of annihilation events in experimental realizations.

Prabhakar, Shashi; Gautam, S; Angom, D

2013-01-01T23:59:59.000Z

207

Magnetic state of K0.8Fe1.6Se2 from a five-orbital Hubbard model in the Hartree-Fock approximation  

SciTech Connect

Motivated by the recent discovery of Fe-based superconductors close to an antiferromagnetic insulator in the experimental phase diagram, here the five-orbital Hubbard model (without lattice distortions) is studied using the real-space Hartree-Fock approximation, employing a 10 10 Fe cluster with Fe vacancies in a5 5 pattern. Varying the Hubbard and Hund couplings, and at electronic density n = 6.0, the phase diagram contains an insulating state with the same spin pattern as observed experimentally, involving 2 2 ferromagnetic plaquettes coupled with one another antiferromagnetically. The presence of local ferromagnetic tendencies is in qualitative agreement with Lanczos results for the three-orbital model also reported here. The magnetic moment 3 B /Fe is in good agreement with experiments. Several other phases are also stabilized in the phase diagram, in agreement with recent calculations using phenomenological models.

Luo, Qinlong [ORNL; Nicholson, Andrew D [ORNL; Riera, J. A. [Universidad Nacional de Rosario; Yao, Dao-Xin [Sun Yat-Sen University, Guangzhou, China; Moreo, Adriana [ORNL; Dagotto, Elbio R [ORNL

2011-01-01T23:59:59.000Z

208

Description of Selected Algorithms and Implementation Details of a Concept-Demonstration Aircraft VOrtex Spacing System (AVOSS)  

Science Conference Proceedings (OSTI)

A ground-based system has been developed to demonstrate the feasibility of automating the process of collecting relevant weather data, predicting wake vortex behavior from a data base of aircraft, prescribing safe wake vortex spacing criteria, estimating ...

Hinton David A.

2001-06-01T23:59:59.000Z

209

Cloud-Resolving Simulations of Mesoscale Vortex Intensification and Its Effect on a Serial Mesoscale Convective System  

Science Conference Proceedings (OSTI)

The authors performed numerical simulations of the 27–28 May 1998 mesoscale convective vortex (MCV) and mesoscale convective system (MCS) to understand how the MCV modulated the convection, and how the convection intensified the vortex. The fifth-...

Christopher A. Davis; Stanley B. Trier

2002-12-01T23:59:59.000Z

210

Experimental and semiempirical method to determine the Pauli-limiting field in quasi-two-dimensional superconductors as applied to ?-(BEDT-TTF)2Cu(NCS)2: strong evidence of a FFLO state  

SciTech Connect

We present upper critical field data for {kappa}-(BEDT-TTF){sub 2}Cu(NCS){sub 2} with the magnetic field close to parallel and parallel to the conducting layers. We show that we can eliminate the effect of vortex dynamics in these layered materials if the layers are oriented within 0.3-inch of parallel to the applied magnetic field. Eliminating vortex effects leaves one remaining feature in the data that corresponds to the Pauli paramagnetic limit (H{sub p}). We propose a semiempirical method to calculate the H{sub p} in quasi-2D superconductors. This method takes into account the energy gap of each of the quasi-2D superconductors, which is calculated from specific-heat data, and the influence of many-body effects. The calculated Pauli paramagnetic limits are then compared to critical field data for the title compound and other organic conductors. Many of the examined quasi-2D superconductors, including the above organic superconductors and CeCoIn{sub 5}, exhibit upper critical fields that exceed their calculated H{sub p} suggesting unconventional superconductivity. We show that the high-field low-temperature state in {kappa}-(BEDT-TTF){sub 2}Cu(NCS){sub 2} is consistent with the Fulde-Ferrell-Larkin-Ovchinnikov state.

Agosta, C. C.; Jin, J.; Coniglio, W. A.; Smith, B. E.; Cho, K.; Mihut, I.; Martin, C.; Tozer, S. W.; Murphy, T. P.; Palm, E. C.; Schlueter, J. A.; Kurmoo, M. (Materials Science Division); (Clark Univ.); (Nat. High Field Magnet Lab.); (The Royal Inst.)

2012-01-01T23:59:59.000Z

211

Type I and Two-Gap Superconductivity in Neutron Star Magnetism  

E-Print Network (OSTI)

Neutron-star inner cores with several charged baryonic components are likely to be analogues of the two-gap superconductor which is of current interest in condensed-matter physics. Consequently, type I superconductivity is less probable than type II but may nevertheless be present in some intervals of matter density. The intermediate state structure formed at finite magnetic flux densities after the superconducting transitions is subject to buoyancy, frictional and neutron-vortex interaction forces. These are estimated and it is shown that the most important frictional force is that produced by the stable stratification of neutron-star matter, the irreversible process being diffusion in the normal, finite magnetic-flux density, parts of the structure. The length-scale of the structure, in directions perpendicular to the local magnetic field is of crucial importance. For small scales, the flux comoves with the neutron vortices, as do the proton vortices of a type II superconductor. But for much larger length-scales, flux movement tends to that expected for normal charged Fermi systems.

P B Jones

2006-06-30T23:59:59.000Z

212

Effects of surface roughness and vortex generators on the LS(1)-0417MOD airfoil  

DOE Green Energy (OSTI)

An 18-inch constant-chord model of the LS(l)-0417MOD airfoil section was tested under two dimensional steady state conditions ate University 7{times}10 Subsonic Wind Tunnel. The objective was to document section lift and moment characteristics model and air flow conditions. Surface pressure data was acquired at {minus}60{degrees} through + 230{degrees} geometric angles of attack, at a nominal 1 million Reynolds number. Cases with and without leading edge grit roughness were investigated. The leading edge mulated blade conditions in the field. Additionally, surface pressure data were acquired for Reynolds numbers of 1.5 and 2.0 million, with and without leading edge grit roughness; the angle of attack was limited to a {minus}20{degrees} to 40{degrees} range. In general, results showed lift curve slope sensitivities to Reynolds number and roughness. The maximum lift coefficient was reduced as much as 29% by leading edge roughness. Moment coefficient showed little sensitivity to roughness beyond 50{degrees} angle of attack, but the expected decambering effect of a thicker boundary layer with roughness did show at lower angles. Tests were also conducted with vortex generators located at the 30% chord location on the upper surface only, at 1 and 1.5 million Reynolds numbers, with and without leading edge grit roughness. In general, with leading edge grit roughness applied, the vortex generators restored 85 percent of the baseline level of maximum lift coefficient but with a more sudden stall break and at a higher angle of attack than the baseline.

Reuss, R.L.; Hoffman, M.J.; Gregorek, G.M. [Ohio State Univ., Columbus, OH (United States)

1995-12-01T23:59:59.000Z

213

Generalized London free energy for high-Tc vortex lattices Ian Affleck  

E-Print Network (OSTI)

Generalized London free energy for high-Tc vortex lattices Ian Affleck Department of Physics-1829 97 50402-4 The London free energy provides a very simple way of studying the vortex lattice that this effect can arise from additional quartic derivative terms in the Ginzburg-Landau GL free energy4­7 or

Franz, Marcel

214

Combustion in Meso-scale Vortex Chambers Ming-hsun Wu*  

E-Print Network (OSTI)

1 Combustion in Meso-scale Vortex Chambers Ming-hsun Wu* , Yanxing Wang, Vigor Yang and Richard A) #12;2 COMBUSTION IN MESO-SCALE VORTEX CHAMBERS Ming-hsun Wu, Yanxing Wang, Vigor Yang and Richard A with the chemical energy varying from 25 to 174W. For the largest combustion volume, hydrogen and hydrocarbons

Yang, Vigor

215

Solution of linear problems of the uniform motion of a vortex source in a multilayer fluid  

Science Conference Proceedings (OSTI)

A method of solving linear problems of the uniform motion of a vortex source in a multilayer fluid having an arbitrary finite number of layers is proposed. As an example, the problem of the motion of a vortex source of given intensity in a three-layer fluid is solved. Formulas for the complex velocities and hydrodynamic reactions are obtained.

Gorlov, S.I.

1995-11-01T23:59:59.000Z

216

Research on Vortex Unstablity Caused by Bending Deformation of Drilling Bar in BTA Deep Hole Machining  

Science Conference Proceedings (OSTI)

Vortex and unstability of bending boring bar caused by cutting fluid force are researched, with Timoshenko beam model and mated vibration model, based on which machining quality of BTA deep hole drilling and tools life can be promoted in practice. Linear ... Keywords: deep hole boring, boring bar, Timoshenko beam, mating vibration, vortex motion stability

Zhanqi Hu; Wu Zhao

2009-04-01T23:59:59.000Z

217

On a Graphics Hardware-Based Vortex Detection and Visualization System  

Science Conference Proceedings (OSTI)

We present a graphics hardware-based system for interactive denoising, vortex detection, and visualization of vector data. No intermediate results need to be read back by the application once the vector field has been loaded onto the graphics adapter. ... Keywords: Flow visualization, Graphics hardware, Vortex detection

S. Stegmaier; T. Ertl

2005-04-01T23:59:59.000Z

218

Control of magnetic, nonmagnetic, and superconducting states in annealed Ca(Fe1?xCox)2As2  

Science Conference Proceedings (OSTI)

We have grown single-crystal samples of Co substituted CaFe2As2 using an FeAs flux and systematically studied the effects of annealing/quenching temperature on the physical properties of these samples. Whereas the as-grown samples (quenched from 960 ?C) all enter the collapsed tetragonal phase upon cooling, annealing/quenching temperatures between 350 and 800 ?C can be used to tune the system to low-temperature antiferromagnetic/orthorhomic or superconducting states as well. The progression of the transition temperature versus annealing/quenching temperature (T-Tanneal) phase diagrams with increasing Co concentration shows that, by substituting Co, the antiferromagnetic/orthorhombic and the collapsed tetragonal phase lines are separated and bulk superconductivity is revealed. We established a 3D phase diagram with Co concentration and annealing/quenching temperature as two independent control parameters. At ambient pressure, for modest x and Tanneal values, the Ca(Fe1?xCox)2As2 system offers ready access to the salient low-temperature states associated with Fe-based superconductors: antiferromagnetic/orthorhombic, superconducting, and nonmagnetic/collapsed tetragonal.

Ran, Sheng; Budko, Serguei L.; Straszheim, Warren E.; Soh, Jing-Han; Kim, Min Gyu; Kreyssig, Andreas; Goldman, Alan I.; Canfield, Paul C.

2012-06-22T23:59:59.000Z

219

Vortex nozzle for segmenting and transporting metal chips from turning operations  

DOE Patents (OSTI)

Apparatus for collecting, segmenting and conveying metal chips from machining operations utilizes a compressed gas driven vortex nozzle for receiving the chip and twisting it to cause the chip to segment through the application of torsional forces to the chip. The vortex nozzle is open ended and generally tubular in shape with a converging inlet end, a constant diameter throat section and a diverging exhaust end. Compressed gas is discharged through angled vortex ports in the nozzle throat section to create vortex flow in the nozzle and through an annular inlet at the entrance to the converging inlet end to create suction at the nozzle inlet and cause ambient air to enter the nozzle. The vortex flow in the nozzle causes the metal chip to segment and the segments thus formed to pass out of the discharge end of the nozzle where they are collected, cleaned and compacted as needed.

Bieg, L.F.

1993-04-20T23:59:59.000Z

220

Vortex nozzle for segmenting and transporting metal chips from turning operations  

DOE Patents (OSTI)

This invention is comprised of an apparatus for collecting, segmenting and conveying metal chips from machining operations which utilizes a compressed gas driven vortex nozzle for receiving the chip and twisting it to cause the chip to segment through the application of torsional forces to the chip. The vortex nozzle is open ended and generally tubular in shape with a converging inlet end, a constant diameter throat section and a diverging exhaust end. Compressed gas is discharged through angled vortex ports in the nozzle throat section to create vortex flow in the nozzle and through an annular inlet at the entrance to the converging inlet end to create suction at the nozzle inlet and cause ambient air to enter the nozzle. The vortex flow in the nozzle causes the metal chip to segment and the segments thus formed to pass out of the discharge end of the nozzle where they are collected, cleaned and compacted as needed.

Bieg, L.F.

1992-12-31T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Direct Characterization of Kerogen by X-ray and Solid-State [superscript 13]C Nuclear Magnetic Resonance Methods  

Science Conference Proceedings (OSTI)

A combination of solid-state {sup 13}C NMR, X-ray photoelectron spectroscopy (XPS) and sulfur X-ray absorption near edge structure (S-XANES) techniques are used to characterize organic oxygen, nitrogen, and sulfur species and carbon chemical/structural features in kerogens. The kerogens studied represent a wide range of organic matter types and maturities. A van Krevelen plot based on elemental H/C data and XPS derived O/C data shows the well established pattern for type I, type II, and type III kerogens. The anticipated relationship between the Rock-Eval hydrogen index and H/C is independent of organic matter type. Carbon structural and lattice parameters are derived from solid-state {sup 13}C NMR analysis. As expected, the amount of aromatic carbon, measured by both {sup 13}C NMR and XPS, increases with decreasing H/C. The correlation between aromatic carbon and Rock-Eval T{sub max}, an indicator of maturity, is linear for types II and IIIC kerogens, but each organic matter type follows a different relationship. The average aliphatic carbon chain length (Cn) decreases with an increasing amount of aromatic carbon in a similar manner across all organic matter types. The fraction of aromatic carbons with attachments (FAA) decreases, while the average number of aromatic carbons per cluster (C) increases with an increasing amount of aromatic carbon. FAA values range from 0.2 to 0.4, and C values range from 12 to 20 indicating that kerogens possess on average 2- to 5-ring aromatic carbon units that are highly substituted. There is basic agreement between XPS and {sup 13}C NMR results for the amount and speciation of organic oxygen. XPS results show that the amount of carbon oxygen single bonded species increases and carbonyl-carboxyl species decrease with an increasing amount of aromatic carbon. Patterns for the relative abundances of nitrogen and sulfur species exist regardless of the large differences in the total amount of organic nitrogen and sulfur seen in the kerogens. XPS and S-XANES results indicate that the relative level of aromatic sulfur increases with an increasing amount of aromatic carbon for all kerogens. XPS show that the majority of nitrogen exists as pyrrolic forms in comparable relative abundances in all kerogens studied. The direct characterization results using X-ray and NMR methods for nitrogen, sulfur, oxygen, and carbon chemical structures provide a basis for developing both specific and general average chemical structural models for different organic matter type kerogens.

Kelemen, S. R.; Afeworki, M.; Gorbaty, M.L.; Sansone, M.; Kwiatek, P.J.; Walters, C.C.; Freund, H.; Siskin, M.; Bence, A.E.; Curry, D.J.; Solum, M.; Pugmire, R.J.; Vandenbroucke, M.; Leblond, M.; Behar, F. (ExxonMobil); (ExxonMobil); (IFP); (Utah)

2008-06-12T23:59:59.000Z

222

Direct Characterization of Kerogen By X-Ray And Solid-State **13C Nuclear Magnetic Resonance Methods  

DOE Green Energy (OSTI)

A combination of solid-state {sup 13}C NMR, X-ray photoelectron spectroscopy (XPS) and sulfur X-ray absorption near edge structure (S-XANES) techniques are used to characterize organic oxygen, nitrogen, and sulfur species and carbon chemical/structural features in kerogens. The kerogens studied represent a wide range of organic matter types and maturities. A van Krevelen plot based on elemental H/C data and XPS derived O/C data shows the well established pattern for type I, type II, and type III kerogens. The anticipated relationship between the Rock-Eval hydrogen index and H/C is independent of organic matter type. Carbon structural and lattice parameters are derived from solid-state 13C NMR analysis. As expected, the amount of aromatic carbon, measured by both {sup 13}C NMR and XPS, increases with decreasing H/C. The correlation between aromatic carbon and Rock-Eval Tmax, an indicator of maturity, is linear for types II and IIIC kerogens, but each organic matter type follows a different relationship. The average aliphatic carbon chain length (Cn') decreases with an increasing amount of aromatic carbon in a similar manner across all organic matter types. The fraction of aromatic carbons with attachments (FAA) decreases, while the average number of aromatic carbons per cluster (C) increases with an increasing amount of aromatic carbon. FAA values range from 0.2 to 0.4, and C values range from 12 to 20 indicating that kerogens possess on average 2- to 5-ring aromatic carbon units that are highly substituted. There is basic agreement between XPS and 13C NMR results for the amount and speciation of organic oxygen. XPS results show that the amount of carbon oxygen single bonded species increases and carbonyl-carboxyl species decrease with an increasing amount of aromatic carbon. Patterns for the relative abundances of nitrogen and sulfur species exist regardless of the large differences in the total amount of organic nitrogen and sulfur seen in the kerogens. XPS and S-XANES results indicate that the relative level of aromatic sulfur increases with an increasing amount of aromatic carbon for all kerogens. XPS show that the majority of nitrogen exists as pyrrolic forms in comparable relative abundances in all kerogens studied. The direct characterization results using X-ray and NMR methods for nitrogen, sulfur, oxygen, and carbon chemical structures provide a basis for developing both specific and general average chemical structural models for different organic matter type kerogens.

Keleman, S.R.; Afeworki, M.; Gorbaty, M.L.; Sansone, M.; Kwiatek, P.J.; Walters, C.C.; Freund, H.; Siskin, M.; Bence, A.E.; Curry, D.J.; Solum, M.; Pugmire, R.J.; Vandenbroucke, M.; Leblond, M.; Behar, F.

2007-07-09T23:59:59.000Z

223

Heat Transfer Enhancement in Separated and Vortex Flows  

SciTech Connect

This document summarizes the research performance done at the Heat Transfer Laboratory of the University of Minnesota on heat transfer and energy separation in separated and vortex flow supported by DOE in the period September 1, 1998--August 31, 2003. Unsteady and complicated flow structures in separated or vortex flows are the main reason for a poor understanding of heat transfer under such conditions. The research from the University of Minnesota focused on the following important aspects of understanding such flows: (1) Heat/mass transfer from a circular cylinder; (2) study of energy separation and heat transfer in free jet flows and shear layers; and (3) study of energy separation on the surface and in the wake of a cylinder in crossflow. The current study used three different experimental setups to accomplish these goals. A wind tunnel and a liquid tunnel using water and mixtures of ethylene glycol and water, is used for the study of prandtl number effect with uniform heat flux from the circular cylinder. A high velocity air jet is used to study energy separation in free jets. A high speed wind tunnel, same as used for the first part, is utilized for energy separation effects on the surface and in the wake of the circular cylinder. The final outcome of this study is a substantial advancement in this research area.

Richard J. Goldstein

2004-05-27T23:59:59.000Z

224

MAGNETIC NEUTRON SCATTERING  

SciTech Connect

Much of our understanding of the atomic-scale magnetic structure and the dynamical properties of solids and liquids was gained from neutron-scattering studies. Elastic and inelastic neutron spectroscopy provided physicists with an unprecedented, detailed access to spin structures, magnetic-excitation spectra, soft-modes and critical dynamics at magnetic-phase transitions, which is unrivaled by other experimental techniques. Because the neutron has no electric charge, it is an ideal weakly interacting and highly penetrating probe of matter's inner structure and dynamics. Unlike techniques using photon electric fields or charged particles (e.g., electrons, muons) that significantly modify the local electronic environment, neutron spectroscopy allows determination of a material's intrinsic, unperturbed physical properties. The method is not sensitive to extraneous charges, electric fields, and the imperfection of surface layers. Because the neutron is a highly penetrating and non-destructive probe, neutron spectroscopy can probe the microscopic properties of bulk materials (not just their surface layers) and study samples embedded in complex environments, such as cryostats, magnets, and pressure cells, which are essential for understanding the physical origins of magnetic phenomena. Neutron scattering is arguably the most powerful and versatile experimental tool for studying the microscopic properties of the magnetic materials. The magnitude of the cross-section of the neutron magnetic scattering is similar to the cross-section of nuclear scattering by short-range nuclear forces, and is large enough to provide measurable scattering by the ordered magnetic structures and electron spin fluctuations. In the half-a-century or so that has passed since neutron beams with sufficient intensity for scattering applications became available with the advent of the nuclear reactors, they have became indispensable tools for studying a variety of important areas of modern science, ranging from large-scale structures and dynamics of polymers and biological systems, to electronic properties of today's technological materials. Neutron scattering developed into a vast field, encompassing many different experimental techniques aimed at exploring different aspects of matter's atomic structure and dynamics. Modern magnetic neutron scattering includes several specialized techniques designed for specific studies and/or particular classes of materials. Among these are magnetic reflectometry aimed at investigating surfaces, interfaces, and multilayers, small-angle scattering for the large-scale structures, such as a vortex lattice in a superconductor, and neutron spin-echo spectroscopy for glasses and polymers. Each of these techniques and many others offer exciting opportunities for examining magnetism and warrant extensive reviews, but the aim of this chapter is not to survey how different neutron-scattering methods are used to examine magnetic properties of different materials. Here, we concentrate on reviewing the basics of the magnetic neutron scattering, and on the recent developments in applying one of the oldest methods, the triple axis spectroscopy, that still is among the most extensively used ones. The developments discussed here are new and have not been coherently reviewed. Chapter 2 of this book reviews magnetic small-angle scattering, and modern techniques of neutron magnetic reflectometry are discussed in Chapter 3.

ZALIZNYAK,I.A.; LEE,S.H.

2004-07-30T23:59:59.000Z

225

Dissipative dynamics of vortex arrays in trapped Bose-condensed gases: neutron stars physics on $?$K scale  

E-Print Network (OSTI)

We develop a theory of dissipative dynamics of large vortex arrays in trapped Bose-condensed gases. We show that in a static trap the interaction of the vortex array with thermal excitations leads to a non-exponential decay of the vortex structure, and the characteristic lifetime depends on the initial density of vortices. Drawing an analogy with physics of pulsar glitches, we propose an experiment which employs the heating of the thermal cloud in the course of the decay of the vortex array as a tool for a non-destructive study of the vortex dynamics.

P. O. Fedichev; A. E. Muryshev

2000-04-17T23:59:59.000Z

226

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

227

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

228

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

229

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

230

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

231

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

232

Not All Nanodisk Magnetic Vortices Are Created Equally  

NLE Websites -- All DOE Office Websites (Extended Search)

Not All Nanodisk Magnetic Vortices Are Created Equally Print Not All Nanodisk Magnetic Vortices Are Created Equally Print Magnetic vortices - hurricanes of magnetism only a few atoms across - have generated intense interest in the high-tech community because of their potential application in nonvolatile random access memory (RAM) data storage systems. A team of researchers led by Peter Fischer and Mi-Young Im of the Center for X-Ray Optics (CXRO) worked in collaboration with scientists in Japan to discover that, contrary to what was previously believed, the formation of magnetic vortices in ferromagnetic nanodisks is an asymmetric phenomenon. This breaking of symmetry could lead to failure in a data storage device during its initialization process. These new findings indicate that the road to magnetic vortex RAM might be more difficult to navigate than previously supposed, but there might be unexpected rewards as well.

233

An adaptive mesh method for the simulation of Blade Vortex Interaction  

E-Print Network (OSTI)

An adaptive mesh method for the simulation of parallel ics. Blade Vortex Interaction (BV1) with an active Trailing Edge Flap (TEF) is presented. The two-dimensional 1111-steady problem is solved by a higher order upwind Euler method for an unstructured mesh. A local mesh adaptation technique is employed to maintain vortex strength by capturing the details of the convecting vortex. The computational technique does not require any assumption on the vortex structure, and, therefore is suitable for close interaction of the vortex and the blade. The adaptive method is based on cell subdivisions and allows for frequent mesh adaptation due to its fast speed. To demonstrate the reduction of numerical dissipation of a vortex via mesh adaptation, we first consider a simple case with a convecting vortex in freestream. Finally, we apply tile techniques to examine the effectiveness of an active TEF on BVI in reducing the pressure perturbations at the airfoil leading edge. For the boundary motion due to TEF deployment, a local recessing procedure is utilized to maintain mesh quality by avoiding distorted mesh elements near the flap.

Kim, Kyu-Sup

1998-01-01T23:59:59.000Z

234

Effects of surface roughness and vortex generators on the NACA 4415 airfoil  

DOE Green Energy (OSTI)

Wind turbines in the field can be subjected to many and varying wind conditions, including high winds with rotor locked or with yaw excursions. In some cases the rotor blades may be subjected to unusually large angles of attack that possibly result in unexpected loads and deflections. To better understand loadings at unusual angles of attack, a wind tunnel test was performed. An 18-inch constant chord model of the NACA 4415 airfoil section was tested under two dimensional steady state conditions in the Ohio State University Aeronautical and Astronautical Research Laboratory (OSU/AARL) 7 x 10 Subsonic Wind Tunnel (7 x 10). The objective of these tests was to document section lift and moment characteristics under various model and air flow conditions. These included a normal angle of attack range of {minus}20{degree} to +40{degree}, an extended angle of attack range of {minus}60{degree} to +230{degree}, applications of leading edge grit roughness (LEGR), and use of vortex generators (VGs), all at chord Reynolds numbers as high as possible for the particular model configuration. To realistically satisfy these conditions the 7 x 10 offered a tunnel-height-to-model-chord ratio of 6.7, suggesting low interference effects even at the relatively high lift and drag conditions expected during the test. Significantly, it also provided chord Reynolds numbers up to 2.0 million. 167 figs., 13 tabs.

Reuss, R.L.; Hoffman, M.J.; Gregorek, G.M. [Ohio State Univ., Columbus, OH (United States)

1995-12-01T23:59:59.000Z

235

Vortex flow in the technology of radiation wave cracking (RWC)  

E-Print Network (OSTI)

This article examines the theory of vortex flows in relation to the processes occurring in the radiation-wave cracking of crude oil, when the crude oil is sprayed into the gas stream in the form of a mist and then is fed into the reactor, where it is treated by the accelerated electrons and the UHF radiation. The output of this process are the products with the specified parameters (high-octane petroleum products). This process operates at the ambient pressure and temperature, which makes the process safer for industrial purposes. Besides the process itself, the authors described the equipment used in this process, as well as the parameters of the optimal process.

L. A. Tsoy; V. N. Kolushov; A. G. Komarov; A. N. Tsoy

2012-09-16T23:59:59.000Z

236

Vortex flow in the technology of radiation wave cracking (RWC)  

E-Print Network (OSTI)

This article examines the theory of vortex flows in relation to the processes occurring in the radiation-wave cracking of crude oil, when the crude oil is sprayed into the gas stream in the form of a mist and then is fed into the reactor, where it is treated by the accelerated electrons and the UHF radiation. The output of this process are the products with the specified parameters (high-octane petroleum products). This process operates at the ambient pressure and temperature, which makes the process safer for industrial purposes. Besides the process itself, the authors described the equipment used in this process, as well as the parameters of the optimal process.

Tsoy, L A; Komarov, A G; Tsoy, A N

2012-01-01T23:59:59.000Z

237

SOLAR MAGNETIZED 'TORNADOES': RELATION TO FILAMENTS  

Science Conference Proceedings (OSTI)

Solar magnetized 'tornadoes', a phenomenon discovered in the solar atmosphere, appear as tornado-like structures in the corona but are rooted in the photosphere. Like other solar phenomena, solar tornadoes are a feature of magnetized plasma and therefore differ distinctly from terrestrial tornadoes. Here we report the first analysis of solar 'tornadoes' (two papers which focused on different aspects of solar tornadoes were published in the Astrophysical Journal Letters and Nature, respectively, during the revision of this Letter). A detailed case study of two events indicates that they are rotating vertical magnetic structures probably driven by underlying vortex flows in the photosphere. They usually exist as a group and are related to filaments/prominences, another important solar phenomenon whose formation and eruption are still mysteries. Solar tornadoes may play a distinct role in the supply of mass and twists to filaments. These findings could lead to a new explanation of filament formation and eruption.

Su Yang; Veronig, Astrid; Temmer, Manuela [IGAM-Kanzelhoehe Observatory, Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Wang Tongjiang [Department of Physics, Catholic University of America, Washington, DC 20064 (United States); Gan Weiqun, E-mail: yang.su@uni-graz.at [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

2012-09-10T23:59:59.000Z

238

Magnetically leviated superconducting bearing  

DOE Patents (OSTI)

A magnetically levitated superconducting bearing includes a magnet (2) mounted on a shaft (12) that is rotatable around an axis of rotation and a Type II superconductor (6) supported on a stator (14) in proximity to the magnet (2). The superconductor (6) is positioned so that when it is cooled to its superconducting state in the presence of a magnetic field, it interacts with the magnet (2) to produce an attractive force that levitates the magnet (2) and supports a load on the shaft (12). The interaction between the superconductor (6) and magnet(2) also produces surface screening currents (8) that generate a repulsive force perpendicular to the load. The bearing also has means for maintaining the superconductor at a temperature below its critical temperature (16, 18). The bearing could also be constructed so the magnet (2) is supported on the stator (14) and the superconductor (6) is mounted on the shaft (12). The bearing can be operated by cooling the superconductor (6) to its superconducting state in the presence of a magnetic field.

Weinberger, Bernard R. (Avon, CT); Lynds, Jr., Lahmer (Glastonbury, CT)

1993-01-01T23:59:59.000Z

239

The Kinematics of a Midlatitude, Continental Mesoscale Convective System and Its Mesoscale Vortex  

Science Conference Proceedings (OSTI)

The authors present a unique, scale-discriminating study of the environment-relative circulations within a mesoscale convective system (MCS) and mesoscale convective vortex (MCV). The MCS, a leading convective line and trailing stratiform region ...

Jason C. Knievel; Richard H. Johnson

2002-07-01T23:59:59.000Z

240

Wave–Current Interaction: A Comparison of Radiation-Stress and Vortex-Force Representations  

Science Conference Proceedings (OSTI)

The vortex-force representation of the wave-averaged effects on currents is compared to the radiation-stress representation in a scaling regime appropriate to coastal and shelf waters. Three-dimensional and vertically integrated expressions for ...

E. M. Lane; J. M. Restrepo; J. C. McWilliams

2007-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Evidence against an Antarctic Stratospheric Vortex Split during the Periods of Pre-IGY Temperature Measurements  

Science Conference Proceedings (OSTI)

Historic upper-air observations from Antarctica are inspected to investigate the uniqueness of the vortex split in the Antarctic spring of 2002. No comprehensive meteorological observations are available prior to the International Geophysical ...

Barbara Naujokat; Howard K. Roscoe

2005-03-01T23:59:59.000Z

242

Midtropospheric Anticyclonic Vortex Street Associated with a Cloud Band near a Cold Front  

Science Conference Proceedings (OSTI)

The characteristics and formation mechanism of an anticyclonic vortex street of meso-? scale, which appeared near a cold front around the Ryukyu Islands, Japan, on 11 April 1995, were examined by an analysis of observational data, a numerical ...

Eizi Toyoda; Hiroshi Niino; Kazuhisa Tsuboki; Ryuji Kimura; Masanori Yoshizaki

1999-08-01T23:59:59.000Z

243

The Uses and Limitations of Contour Advection as a Technique for Examining Arctic Vortex Dynamics  

Science Conference Proceedings (OSTI)

A contour advection technique, contour advection with surgery (CAS), is applied to the Northern Hemisphere Arctic vortex during several dynamically active periods in midwinter and at several different levels in the stratosphere. The ability of ...

Michael N. Baker; Derek M. Cunnold

2001-08-01T23:59:59.000Z

244

The Garden City, Kansas, Storm during VORTEX 95. Part II: The Wall Cloud and Tornado  

Science Conference Proceedings (OSTI)

On 16 May 1995, a supercell storm produced an F1 tornado near Garden City, Kansas, during VORTEX (Verification of the Origins of Rotation in Tornadoes Experiment). This event provided the first opportunity to synthesize data collected by a new ...

Roger M. Wakimoto; Chinghwang Liu

1998-02-01T23:59:59.000Z

245

The Effect of Tropospheric Jet Latitude on Coupling between the Stratospheric Polar Vortex and the Troposphere  

Science Conference Proceedings (OSTI)

A dry general circulation model is used to investigate how coupling between the stratospheric polar vortex and the extratropical tropospheric circulation depends on the latitude of the tropospheric jet. The tropospheric response to an identical ...

Chaim I. Garfinkel; Darryn W. Waugh; Edwin P. Gerber

2013-03-01T23:59:59.000Z

246

The Role of Multiple Vortex Tornado Structure in Causing Storm Researcher Fatalities  

Science Conference Proceedings (OSTI)

A large and violent tornado/multiple vortex mesocyclone (MVMC) / tornado tracked east and northeastward near El Reno, Oklahoma on 31-May-2013, causing eight fatalities, including storm-chasers/researchers attempting to deploy in-situ instrumentation. Sub-...

Joshua Wurman; Karen Kosiba; Paul Robinson; Tim Marshall

247

A Concentrated Outbreak of Tornadoes, Downbursts and Microbursts, and Implications Regarding Vortex Classification  

Science Conference Proceedings (OSTI)

A remarkable case of severe weather occurred near Springfield, Illinois on 6 August 1977. Aerial and ground surveys revealed that 17 cyclonic vortices an anticyclonic vortex, 10 downbursts and 19 microbursts occurred in a limited (20 km × 40 km) ...

Gregory S. Forbes; Roger M. Wakimoto

1983-01-01T23:59:59.000Z

248

Jovian Dynamics. Part II: The Genesis and Equilibration of Vortex Sets  

Science Conference Proceedings (OSTI)

To extend studies of the dynamics of thin atmospheric layers, the generation and equilibration of multiple anticyclonic vortex sets associated with long solitary baroclinic Rossby waves are examined numerically using a primitive equation model ...

G. P. Williams

2002-04-01T23:59:59.000Z

249

Structure of a Midtropospheric Vortex Induced by a Mesoscale Convective System  

Science Conference Proceedings (OSTI)

On 9 June 1988 a mesoscale (200-km diameter) convectively generated vortex (MCV) passed through the Colorado wind-profiling network. The generating convective system, which was too small to meet Maddox’s mesoscale convective complex criteria, ...

Diana L. Bartels; John M. Brown; Edward I. Tollerud

1997-02-01T23:59:59.000Z

250

A Vortex-Based Perspective of Eastern Pacific Tropical Cyclone Formation  

Science Conference Proceedings (OSTI)

Tropical cyclone formation over the eastern Pacific during 2005 and 2006 was examined using primarily global operational analyses from the National Centers for Environmental Prediction. This paper represents a “vortex view” of genesis, adding to ...

Christopher Davis; Chris Snyder; Anthony C. Didlake Jr.

2008-07-01T23:59:59.000Z

251

Observations of a Storm Containing Misocyclones, Downbursts, and Horizontal Vortex Circulations  

Science Conference Proceedings (OSTI)

On 30 June 1982, a multicellular storm in Colorado produced four downbursts, three misocyclones, a miso-anticyclone, and horizontal vortex circulations within a relatively small area of the storm. Weather events associated with this storm ...

Cathy J. Kessinger; David B. Parsons; James W. Wilson

1988-10-01T23:59:59.000Z

252

The Role of Vortex and Environment Errors in Genesis Forecasts of Hurricanes Danielle and Karl (2010)  

Science Conference Proceedings (OSTI)

An ensemble of Weather Research and Forecasting Model (WRF) forecasts initialized from a cycling ensemble Kalman filter (EnKF) system is used to evaluate the sensitivity of Hurricanes Danielle and Karl’s (2010) genesis forecasts to vortex and ...

Ryan D. Torn; David Cook

2013-01-01T23:59:59.000Z

253

An Analytic Vortex Initialization Technique for Idealized Tropical Cyclone Studies in AGCMs  

Science Conference Proceedings (OSTI)

The paper discusses the design of idealized tropical cyclone experiments in atmospheric general circulation models (AGCMs). The evolution of an initially weak, warm-core vortex is investigated over a 10-day period with varying initial conditions ...

Kevin A. Reed; Christiane Jablonowski

2011-02-01T23:59:59.000Z

254

Parametric Representation of the Primary Hurricane Vortex. Part II: A New Family of Sectionally Continuous Profiles  

Science Conference Proceedings (OSTI)

For applications such as windstorm underwriting or storm-surge forecasting, hurricane wind profiles are often approximated by continuous functions that are zero at the vortex center, increase to a maximum in the eyewall, and then decrease ...

H. E. Willoughby; R. W. R. Darling; M. E. Rahn

2006-04-01T23:59:59.000Z

255

The Gradient Genesis of Stratospheric Trace Species in the Subtropics and around the Polar Vortex  

Science Conference Proceedings (OSTI)

Mechanisms that control the formation and decay of meridional gradients in stratospheric trace species in the subtropics and around the polar vortex are investigated using a gradient genesis equation that uses mass-weighted isentropic zonal ...

Kazuyuki Miyazaki; Toshiki Iwasaki

2008-02-01T23:59:59.000Z

256

A Mesoscale Vortex Couplet Observed in the Trailing Anvil of a Multicellular Convective Complex  

Science Conference Proceedings (OSTI)

Observations collected during the Oklahoma–Kansas PRE-STORM experiment are used to document the evolution and structure of a mesoscale vortex couplet that developed in the mesoscale convective system that occurred on 16–17 June 1985. The ...

Johannes Verlinde; William R. Cotton

1990-05-01T23:59:59.000Z

257

The Splitting of the Stratospheric Polar Vortex in the Southern Hemisphere, September 2002: Dynamical Evolution  

Science Conference Proceedings (OSTI)

The polar vortex of the Southern Hemisphere (SH) split dramatically during September 2002. The large-scale dynamical effects were manifest throughout the stratosphere and upper troposphere, corresponding to two distinct cyclonic centers in the ...

Andrew J. Charlton; Alan O’Neill; William A. Lahoz; Paul Berrisford

2005-03-01T23:59:59.000Z

258

Ensemble Forecasting of Tropical Cyclone Motion Using a Barotropic Model. Part II: Perturbations of the Vortex  

Science Conference Proceedings (OSTI)

In Part I of this study, the technique of ensemble forecasting is applied to the problem of tropical cyclone motion prediction by perturbing the environmental flow. In this part, the focus is shifted to perturbation of the vortex structure. The ...

Kevin K. W. Cheung; Johnny C. L. Chan

1999-11-01T23:59:59.000Z

259

Influence of Balanced Motions on Heavy Precipitation within a Long-Lived Convectively Generated Vortex  

Science Conference Proceedings (OSTI)

The forcing of heavy precipitation within a long-lived convectively generated mesoscale vortex (MCV) is investigated with the aid of diagnoses from Rapid Update Cycle gridded analyses. Organized convection within the MCV followed a distinct ...

Stanley B. Trier; Christopher A. Davis

2002-04-01T23:59:59.000Z

260

Source of Gravity Waves within a Vortex-Dipole Jet Revealed by a Linear Model  

Science Conference Proceedings (OSTI)

This study develops a linear numerical model to address the source mechanism of the gravity waves generated within a vortex dipole simulated in a fully nonlinear nonhydrostatic mesoscale model. The background flow for this linear model is ...

Shuguang Wang; Fuqing Zhang

2010-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Submonthly Polar Vortex Variability and Stratosphere–Troposphere Coupling in the Arctic  

Science Conference Proceedings (OSTI)

A principal component analysis is performed to characterize intraseasonal variability in the boreal stratospheric polar vortex. In contrast to previous studies, the current analysis examines daily zonal-mean variability within a limited spatial ...

Robert X. Black; Brent A. McDaniel

2009-11-01T23:59:59.000Z

262

A New Parametric Model of Vortex Tangential-Wind Profiles: Development, Testing, and Verification  

Science Conference Proceedings (OSTI)

A new parametric model of vortex tangential-wind profiles is presented that is primarily designed to depict realistic-looking tangential wind profiles such as those in intense atmospheric vortices arising in dust devils, waterspouts, tornadoes, ...

Vincent T. Wood; Luther W. White

2011-05-01T23:59:59.000Z

263

Maximum Likelihood Estimates of Vortex Parameters from Simulated Coherent Doppler Lidar Data  

Science Conference Proceedings (OSTI)

The performance of pulsed coherent Doppler lidar in estimating aircraft trailing wake vortices by scanning across the aircraft flight track is evaluated using Monte Carlo lidar simulations of a simple vortex pair in both a nonturbulent and ...

Rod Frehlich; Robert Sharman

2005-02-01T23:59:59.000Z

264

An Observational Study of the Final Breakdown of the Southern Hemisphere Stratospheric Vortex in 2002  

Science Conference Proceedings (OSTI)

The 2002 Southern Hemisphere final warming occurred early, following an unusually active winter and the first recorded major warming in the Antarctic. The breakdown of the stratospheric polar vortex in October and November 2002 is examined using ...

Yvan J. Orsolini; Cora E. Randall; Gloria L. Manney; Douglas R. Allen

2005-03-01T23:59:59.000Z

265

A Subtropical Oceanic Mesoscale Convective Vortex Observed during SoWMEX/TiMREX  

Science Conference Proceedings (OSTI)

This study examines a subtropical oceanic mesoscale convective vortex (MCV) that occurred from 1800 UTC 4 June to 1200 UTC 6 June 2008 during intensive observing period (IOP) 6 of the Southwest Monsoon Experiment (SoWMEX) and the Terrain-...

Hsiao-Wei Lai; Christopher A. Davis; Ben Jong-Dao Jou

2011-08-01T23:59:59.000Z

266

Intense Vortex Motion on the Beta Plane: Development of the Beta Gyres  

Science Conference Proceedings (OSTI)

An analytical theory is presented for the self-induced translation of an intense vortex relative to a uniform background flow on the ? plane. The equivalent barotropic approximation is used to formulate the initial value problem within a polar ...

Georgi G. Sutyrin; Glenn R. Flierl

1994-03-01T23:59:59.000Z

267

Interaction of a Baroclinic Vortex with Background Shear: Application to Hurricane Movement  

Science Conference Proceedings (OSTI)

Most extant studies of tropical cyclone movement consider a barotropic vortex on a ? plane. However, observations have shown that real tropical cyclones are strongly baroclinic, with broad anticyclones aloft. Also, the distribution of the large-...

Chun-Chieh Wu; Kerry A. Emanuel

1993-01-01T23:59:59.000Z

268

Enhancement of vortex induced forces and motion through surface roughness control  

SciTech Connect

Roughness is added to the surface of a bluff body in a relative motion with respect to a fluid. The amount, size, and distribution of roughness on the body surface is controlled passively or actively to modify the flow around the body and subsequently the Vortex Induced Forces and Motion (VIFM). The added roughness, when designed and implemented appropriately, affects in a predetermined way the boundary layer, the separation of the boundary layer, the level of turbulence, the wake, the drag and lift forces, and consequently the Vortex Induced Motion (VIM), and the fluid-structure interaction. The goal of surface roughness control is to increase Vortex Induced Forces and Motion. Enhancement is needed in such applications as harnessing of clean and renewable energy from ocean/river currents using the ocean energy converter VIVACE (Vortex Induced Vibration for Aquatic Clean Energy).

Bernitsas, Michael M. (Saline, MI); Raghavan, Kamaldev (Houston, TX)

2011-11-01T23:59:59.000Z

269

Vortex Lattice Structures of a Bose-Einstein Condensate in a Rotating Lattice Potential  

E-Print Network (OSTI)

We study vortex lattice structures of a trapped Bose-Einstein condensate in a rotating lattice potential by numerically solving the time-dependent Gross-Pitaevskii equation. By rotating the lattice potential, we observe the transition from the Abrikosov vortex lattice to the pinned lattice. We investigate the transition of the vortex lattice structure by changing conditions such as angular velocity, intensity, and lattice constant of the rotating lattice potential. PACS numbers: 03.75.Lm, 03.75.Kk Quantized vortices are one of the most characteristic manifestations of superfluidity associated with a Bose-Einstein condensate (BEC) in atomic gases. By rotating anisotropic trap potentials, several experimental groups observed formation of triangular Abrikosov lattices of vortices in rotating BECs 1,2,3. Microscopic mechanism of the vortex lattice formation has been extensively studied both analytically and numerically using the Gross-Pitaevskii (GP) equation for the condensate wavefunction 4,5,6,7,8,9,10,11. More recently, the vortex phase diagrams of a BEC in rotating lattice potentials have attracted theoretical attention, since one expects vortex pinning and structural phase transition of vortex lattice structures 12,13,14. Recently, a rotating lattice has been experimentally realized at JILA, makinig use of a laser beam passing through a rotating mask 12. Stimulated by the recent JILA experiment, in this paper, we study vortex lattice structures of a BEC in a rotating triangular lattice potential created by blue-detuned laser beams. We numerically solve the two-dimensional Gross-Pitaevskii (GP) equa-T. Sato, T. Ishiyama and T. Nikuni Fig. 1. Density profile (a) and Structure factor profile (b) of BEC in the lattice potential. The lattice potential geometry is triangular lattice at a/aho = 2.2 and ?/aho = 0.65. tion in a frame rotationg with anguler velocity ?: (i ? ?)¯h ??(r,t)

Toshihiro Sato; Tomohiko Ishiyama; Tetsuro Nikuni

2006-01-01T23:59:59.000Z

270

Dynamic Switching of the Spin Circulation in Tapered Magnetic Nanodisks  

NLE Websites -- All DOE Office Websites (Extended Search)

Dynamic Switching of the Spin Dynamic Switching of the Spin Circulation in Tapered Magnetic Nanodisks Dynamic Switching of the Spin Circulation in Tapered Magnetic Nanodisks Print Monday, 22 April 2013 12:09 fischer-magnetic vortices Ferromagnetic NiFe disks (500-nm-wide and 20-nm-thick), were fabricated by e-beam lithography onto a waveguide structure. Field pulses, generated by launching current pulses into the waveguide trigger the magnetization dynamics in the elements. Using the soft x-ray microscope XM-1 providing 25-nm spatial resolution, circularly polarized soft x-rays give rise to XMCD contrast which allows to record an image of the in-plane circulation of the magnetic vortex. The topology of vortices-areas where there is a spinning motion around an imaginary axis-is a physical phenomenon which is found across a large

271

Near-Surface Vortex Structure in a Tornado and in a Sub-Tornado-Strength, Convective-Storm Vortex Observed by a Mobile, W-Band Radar During VORTEX2  

Science Conference Proceedings (OSTI)

As part of the VORTEX2 field campaign, a very high-resolution, mobile, W-band Doppler radar collected near-surface (?200 m AGL) observations in an EF-0 tornado near Tribune, Kansas on 25 May 2010 and in sub-tornado-strength vortices near Prospect ...

Robin L. Tanamachi; Howard B. Bluestein; Ming Xue; Wen-Chau Lee; Krzysztof A. Orzel; Stephen J. Frasier; Roger M. Wakimoto

272

Superconducting Magnets  

NLE Websites -- All DOE Office Websites (Extended Search)

magnet technology has allowed physicists to attain higher energies in circular accelerators. One can obtain higher magnetic fields because there is no resistance in a...

273

UNIVERSITY OF CALIFORNIA, SAN DIEGO Experiments on Vortex Symmetrization in Magnetized Electron Plasma Columns  

E-Print Network (OSTI)

. Soloshenko IA et al (2000) Plasma Phys Reports 26:792 22. Laroussi M, Mendis DA, Rosenberg M (2003) New J

California at San Diego, University of

274

Bipolar pulse field for magnetic refrigeration  

DOE Patents (OSTI)

A magnetic refrigeration apparatus includes first and second steady state magnets, each having a field of substantially equal strength and opposite polarity, first and second bodies made of magnetocaloric material disposed respectively in the influence of the fields of the first and second steady state magnets, and a pulsed magnet, concentric with the first and second steady state magnets, and having a field which cycles between the fields of the first and second steady state magnets, thereby cyclically magnetizing and demagnetizing and thus heating and cooling the first and second bodies. Heat exchange apparatus of suitable design can be used to expose a working fluid to the first and second bodies of magnetocaloric material. A controller is provided to synchronize the flow of working fluid with the changing states of magnetization of the first and second bodies. 2 figs.

Lubell, M.S.

1994-10-25T23:59:59.000Z

275

Nonlinear dynamics of drift structures in a magnetized dissipative plasma  

SciTech Connect

A study is made of the nonlinear dynamics of solitary vortex structures in an inhomogeneous magnetized dissipative plasma. A nonlinear transport equation for long-wavelength drift wave structures is derived with allowance for the nonuniformity of the plasma density and temperature equilibria, as well as the magnetic and collisional viscosity of the medium and its friction. The dynamic equation describes two types of nonlinearity: scalar (due to the temperature inhomogeneity) and vector (due to the convectively polarized motion of the particles of the medium). The equation is fourth order in the spatial derivatives, in contrast to the second-order Hasegawa-Mima equations. An analytic steady solution to the nonlinear equation is obtained that describes a new type of solitary dipole vortex. The nonlinear dynamic equation is integrated numerically. A new algorithm and a new finite difference scheme for solving the equation are proposed, and it is proved that the solution so obtained is unique. The equation is used to investigate how the initially steady dipole vortex constructed here behaves unsteadily under the action of the factors just mentioned. Numerical simulations revealed that the role of the vector nonlinearity is twofold: it helps the dispersion or the scalar nonlinearity (depending on their magnitude) to ensure the mutual equilibrium and, thereby, promote self-organization of the vortical structures. It is shown that dispersion breaks the initial dipole vortex into a set of tightly packed, smaller scale, less intense monopole vortices-alternating cyclones and anticyclones. When the dispersion of the evolving initial dipole vortex is weak, the scalar nonlinearity symmetrically breaks a cyclone-anticyclone pair into a cyclone and an anticyclone, which are independent of one another and have essentially the same intensity, shape, and size. The stronger the dispersion, the more anisotropic the process whereby the structures break: the anticyclone is more intense and localized, while the cyclone is less intense and has a larger size. In the course of further evolution, the cyclone persists for a relatively longer time, while the anticyclone breaks into small-scale vortices and dissipation hastens this process. It is found that the relaxation of the vortex by viscous dissipation differs in character from that by the frictional force. The time scale on which the vortex is damped depends strongly on its typical size: larger scale vortices are longer lived structures. It is shown that, as the instability develops, the initial vortex is amplified and the lifetime of the dipole pair components-cyclone and anticyclone-becomes longer. As time elapses, small-scale noise is generated in the system, and the spatial structure of the perturbation potential becomes irregular. The pattern of interaction of solitary vortex structures among themselves and with the medium shows that they can take part in strong drift turbulence and anomalous transport of heat and matter in an inhomogeneous magnetized plasma.

Aburjania, G. D.; Rogava, D. L. [Tbilisi State University, I. Vekua Institute of Applied Mathematics (Georgia); Kharshiladze, O. A. [Ivane Javakhishvili Tbilisi State University (Georgia)

2011-06-15T23:59:59.000Z

276

ANALYTICAL STUDY OF SOME ASPECTS OF VORTEX TUBES FOR GAS-PHASE FISSION HEATING  

DOE Green Energy (OSTI)

Several problems connected with vortex cavity reactors were studied analytically. They include, the generation of high-strength vortices by utilization of bleed through a porous tube wall to stabilize the shear layer on the wall; the nuclear criticality problem; the suitability of various compounds of plutonium as gaseous fissionable materials; and the problem of retaining the fission fragments within the vortex tube. It is concluded that the shear layer on the vortex tube wall can be stabilized if a mass flow greater than or equal to the vortex through flow is bled through the porous wall, and that the tangential Mach numbers which can be obtained are then slightly more than one-half the inviscid values. Beryllium oxide or graphite-moderated reactors of reasonable size and weight can attain criticality if the product of the hydrogen pressure in the vortex core and the maximum value of the ratio of fissionable gas density to hydrogen density in the tube is greater than about 100 atm. The reactor weights are then in the order of 10,000 lb or less. Of the several compounds of plutonium considered as gaseous fuel carriers, plutonium trifluoride and plutonium tribromide appear to be the most promising. It is probable that they can be held in gaseous form in hydrogen, under the desired concentrations. The rate of loss of fission fragments from the vortex tube can be reduced to a small fraction of the rate of their generation by making the vortex tubes about twice the minimum size that is allowable for satisfactory retention of the fissionable material. (auth)

Kerrebrock, J.L.; Lafyatis, P.G.

1958-07-21T23:59:59.000Z

277

Magnetically Driven Accretion  

E-Print Network (OSTI)

We carried out 2.5-dimensional resistive magnetohydrodynamic simulations to study the effects of magnetic diffusivity on magnetically driven mass accretion and jet formation. The initial state is a constant angular-momentum torus threaded by large-scale vertical magnetic fields. Since the angular momentum of the torus is extracted due to magnetic braking, the torus medium falls toward the central region. The infalling matter twists the large-scale magnetic fields and drives bipolar jets. We found that (1) when the normalized magnetic diffusivity, ¯? ? ?/(r0VK0), where VK0 is the Keplerian rotation speed at a reference radius r = r0, is small (¯? ? 10 ?3), mass accretion and jet formation take place intermittently; (2) when 10 ?3 ? ¯? ? 10 ?2, the system evolves toward a quasi-steady state; and (3) when ¯? ? 10 ?2 the accretion/mass 1 outflow rate decreases with ¯? and approaches 0. The results of these simulations indicate that in the center of a galaxy which has a super-massive ( ? 10 9 M?) black hole, a massive ( ? 10 8 M?) gas torus and magnetic braking provide a mass accretion rate which is sufficient to explain the activity of AGNs when ¯? ? 5 × 10?2.

Takuhito Kuwabara; Kazunari Shibata; Takahiro Kudoh

2000-01-01T23:59:59.000Z

278

Increase of pinning with temperature for a single vortex line in superfluid helium  

E-Print Network (OSTI)

While vortex pinning in superconductors usually becomes weaker at higher temperatures, we find the opposite behavior for a single vortex line in superfluid 4 He. The pinning steadily increases over our entire measurement range, from 0.15Tc to over 0.5Tc. We propose Kelvin waves along the vortex as a depinning mechanism with the observed temperature behavior. PACS numbers: 67.40.Vs, 74.60.Ge Pinning sites can trap vortices in a variety of systems. In superconductors, where vortex motion leads to non-zero resistance, a vast amount of work has been devoted to preventing such motion by introducing defects. Experimental work has shown that defects comparable in size to the vortex core make effective pin centers, and that straight [1] or splayed [2] line defects can increase the pin strength. Yet the mechanisms by which vortices interact with pin sites remain unresolved. Experimentally, pinning becomes weaker as temperature increases, in accord with the general assumption that depinning

L. A. K. Donev; L. Hough; R. J. Zieve

2000-01-01T23:59:59.000Z

279

OTEC cold water pipe design for problems caused by vortex-excited oscillations  

DOE Green Energy (OSTI)

Vortex-excited oscillations of marine structures result in reduced fatigue life, large hydrodynamic forces and induced stresses, and sometimes lead to structural damage and to diestructive failures. The cold water pipe of an OTEC plant is nominally a bluff, flexible cylinder with a large aspect ratio (L/D = length/diameter), and is likely to be susceptible to resonant vortex-excited oscillations. The objective of this report is to survey recent results pertaining to the vortex-excited oscillations of structures in general and to consider the application of these findings to the design of the OTEC cold water pipe. Practical design calculations are given as examples throughout the various sections of the report. This report is limited in scope to the problems of vortex shedding from bluff, flexible structures in steady currents and the resulting vortex-excited oscillations. The effects of flow non-uniformities, surface roughness of the cylinder, and inclination to the incident flow are considered in addition to the case of a smooth cyliner in a uniform stream. Emphasis is placed upon design procedures, hydrodynamic coefficients applicable in practice, and the specification of structural response parameters relevant to the OTEC cold water pipe. There are important problems associated with in shedding of vortices from cylinders in waves and from the combined action of waves and currents, but these complex fluid/structure interactions are not considered in this report.

Griffin, O. M.

1980-03-14T23:59:59.000Z

280

Characterization of The Dalles Dam Spillbay 6 Vortex Using Surface Entrained Sensor Fish Device: Preliminary Report  

DOE Green Energy (OSTI)

This document summarizes the pilot study to characterize The Dalles Dam Spillbay 6 vortex using a surface entrained Sensor Fish device. It was conducted by Pacific Northwest National Laboratory (PNNL) on April 13 and 14, 2006. The total spill was controlled at approximately 110 kcfs, the forebay elevation was 157.89 ft, and the discharge of Bay 6 at the tested gate opening of 14 ft was approximately 18 kcfs. The objectives of the full study are to (1) develop baseline conditions for the detailed analysis of Sensor Fish measurements by deploying Sensor Fish in different surface locations in the vortex periphery; (2) observe the entrainment pattern and extract hydraulic data of interest such as acceleration, rotation, pressure, and estimated velocity of Sensor Fish or drogues; (3) integrate the experimental results with companion computational fluid dynamics (CFD) simulations and inertial particle tracking studies. A total of 12 Sensor Fish were released in the surface at upstream edge, left edge, downstream edge, and the core of the vortex at Bay 6. Because of the high discharge, the vortex patterns at the test condition were less consistent than the patterns observed at lower discharges. Compared with the Sensor Fish released at mid-bay at Bay 6, Sensor Fish released from the surface at the vortex experienced higher pressure fluctuations, a larger percentage of severe events, and much more rapid angular velocities.

Deng, Zhiqun; Richmond, Marshall C.; Carlson, Thomas J.

2006-06-22T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Fast superconducting magnetic field switch  

DOE Patents (OSTI)

The superconducting magnetic switch or fast kicker magnet is employed with an electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater than the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles. Magnetic switches and particularly fast kicker magnets are used in the accelerator industry to quickly deflect particle beams into and out of various transport lines, storage rings, dumps, and specifically to differentially route individual bunches of particles from a train of bunches which are injected or ejected from a given ring.

Goren, Y.; Mahale, N.K.

1995-12-31T23:59:59.000Z

282

Structure and Evolution of the Large-Scale Flow and an Embedded Upper-Tropospheric Cyclonic Vortex over Northeast Brazil  

Science Conference Proceedings (OSTI)

Horizontal structure and evolution of large-scale flow and an embedded synoptic-scale cyclonic vortex over northeast Brazil as separate systems and dynamical interaction between them are studied at 200 hPa. A quasi-stationary cyclonic vortex with ...

S. K. Mishra; V. B. Rao; M. A. Gan

2001-07-01T23:59:59.000Z

283

Vortex combustor for low NOX emissions when burning lean premixed high hydrogen content fuel  

Science Conference Proceedings (OSTI)

A trapped vortex combustor. The trapped vortex combustor is configured for receiving a lean premixed gaseous fuel and oxidant stream, where the fuel includes hydrogen gas. The trapped vortex combustor is configured to receive the lean premixed fuel and oxidant stream at a velocity which significantly exceeds combustion flame speed in a selected lean premixed fuel and oxidant mixture. The combustor is configured to operate at relatively high bulk fluid velocities while maintaining stable combustion, and low NOx emissions. The combustor is useful in gas turbines in a process of burning synfuels, as it offers the opportunity to avoid use of diluent gas to reduce combustion temperatures. The combustor also offers the possibility of avoiding the use of selected catalytic reaction units for removal of oxides of nitrogen from combustion gases exiting a gas turbine.

Steele, Robert C; Edmonds, Ryan G; Williams, Joseph T; Baldwin, Stephen P

2012-11-20T23:59:59.000Z

284

Vortex combustor for low NOx emissions when burning lean premixed high hydrogen content fuel  

DOE Patents (OSTI)

A trapped vortex combustor. The trapped vortex combustor is configured for receiving a lean premixed gaseous fuel and oxidant stream, where the fuel includes hydrogen gas. The trapped vortex combustor is configured to receive the lean premixed fuel and oxidant stream at a velocity which significantly exceeds combustion flame speed in a selected lean premixed fuel and oxidant mixture. The combustor is configured to operate at relatively high bulk fluid velocities while maintaining stable combustion, and low NOx emissions. The combustor is useful in gas turbines in a process of burning synfuels, as it offers the opportunity to avoid use of diluent gas to reduce combustion temperatures. The combustor also offers the possibility of avoiding the use of selected catalytic reaction units for removal of oxides of nitrogen from combustion gases exiting a gas turbine.

Steele, Robert C. (Woodinville, WA); Edmonds, Ryan G. (Renton, WA); Williams, Joseph T. (Kirkland, WA); Baldwin, Stephen P. (Winchester, MA)

2009-10-20T23:59:59.000Z

285

Scaling laws for the tropical cyclone derived from the stationary atmospheric vortex equation  

E-Print Network (OSTI)

We present results of a numerical study of the differential equation governing the stationary states of the two-dimensional planetary atmosphere and magnetized plasma (within the Charney Hasegawa Mima model). The results show an interesting similarity with the morphology of a tropical cyclone. Quantitative comparisons are also favorable and several scaling laws can be formulated connecting the charactersistic physical parameters of the tropical cyclone.

Spineanu, F; Spineanu, Florin; Vlad, Madalina

2006-01-01T23:59:59.000Z

286

The investigation of anomalous magnetization in the Raft River valley,  

Open Energy Info (EERE)

investigation of anomalous magnetization in the Raft River valley, investigation of anomalous magnetization in the Raft River valley, Idaho Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: The investigation of anomalous magnetization in the Raft River valley, Idaho Details Activities (1) Areas (1) Regions (0) Abstract: Cassia County Idaho; clastic sediments; economic geology; exploration; geophysical methods; geophysical surveys; geothermal energy; gravel; ground methods; Idaho; isothermal remanent magnetization; magnetic anomalies; magnetic methods; magnetic properties; magnetic susceptibility; magnetization; paleomagnetism; Raft River basin; remanent magnetization; sediments; surveys; United States Author(s): Anderson, L.A.; Mabey, D.R. Published: Abstracts - Society of Exploration Geophysicists International

287

Magnetic Storms  

Science Conference Proceedings (OSTI)

... magnetic reversal. As there is no predictive science of geomagnetism, we currently lack even simple forecasts. Our scientific ...

2010-10-05T23:59:59.000Z

288

Magnetic Imaging  

Science Conference Proceedings (OSTI)

... data-storage and permanent magnets with increased energy products, in ... Optimization of future materials, including improved yields, requires an ...

2012-10-02T23:59:59.000Z

289

Magnetic Properties  

Science Conference Proceedings (OSTI)

...Since the discovery of high-temperature superconductors in 1986 (Ref 10), the demonstration of magnetic flux exclusion

290

Magnetic Resonance Facility (Fact Sheet)  

DOE Green Energy (OSTI)

This fact sheet provides information about Magnetic Resonance Facility capabilities and applications at NREL's National Bioenergy Center. Liquid and solid-state analysis capability for a variety of biomass, photovoltaic, and materials characterization applications across NREL. NREL scientists analyze solid and liquid samples on three nuclear magnetic resonance (NMR) spectrometers as well as an electron paramagnetic resonance (EPR) spectrometer.

Not Available

2012-03-01T23:59:59.000Z

291

Laminated composite of magnetic alloy powder and ceramic ...  

Laminated composite of magnetic alloy powder and ceramic powder and process for making same United States Patent

292

Photo of the Week: Controlling Chaos with Magnetic Fields | Department of  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Controlling Chaos with Magnetic Fields Controlling Chaos with Magnetic Fields Photo of the Week: Controlling Chaos with Magnetic Fields January 18, 2013 - 11:26am Addthis This artistic rendition of "spin vortices" illustrates tiny magnetic vortices that spin according to the polarization of each disk's vortex core. At Argonne National Laboratory, scientists are using alternating magnetic fields to control the behavior of these spin vortices, which are small dots made of iron and nickel. The experiments will help to create new, more efficient magnetic devices -- like the random access memory (RAM) in the device you are using to look at this very photo. Learn more about spin vortices. | Photo courtesy of Sander Munster, Dresden University of Technology.

293

Magnetic Nanostructures in Modern Technology: Spintronics, Magnetic MEMS and Recording, 1st edition  

Science Conference Proceedings (OSTI)

A team of outstanding scientists in the field of modern magnetic nanotechnologies illustrates the state of the art in several areas of advanced magneto-electronic devices, magnetic micro-electromechanical systems and high density information storage ...

Bruno Azzerboni; Giovanni Asti; Luigi Pareti; Massimo Ghidini

2007-10-01T23:59:59.000Z

294

Effect on C-axis transport properties of a critical state in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}  

SciTech Connect

At low temperatures, the c-axis transport properties of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} single crystals depend strongly on the magnetic field history for fields applied along the c-axis, indicating the effect of a critical state in the ab direction. In this study, the authors report zero field cooled (ZFC), field cooled warming (FCW), and field cooled cooling (FCC) c-axis transport properties. In addition, they also report magnetic relaxation measurements on the same samples to identify the c-axis dissipation mechanism. They observe a relaxation of the c-axis resistivity that follows the relaxation of the flux profile across the ab plane. By identifying the irreversible temperature vs. magnetic field for H // c, they construct a phase diagram of vortex states. Finally, they will discuss the implication of the phase diagram and the features related to the transport properties of the Josephson-coupled system and the role of pancake vortices in highly two-dimensional superconductors.

Cho, J.H.; Maley, M.P.; Bulaevskii, L.N.

1995-12-31T23:59:59.000Z

295

Fast superconducting magnetic field switch  

DOE Patents (OSTI)

The superconducting magnetic switch or fast kicker magnet is employed with electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater that the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles.

Goren, Yehuda (Mountain View, CA); Mahale, Narayan K. (The Woodlands, TX)

1996-01-01T23:59:59.000Z

296

Linear and Nonlinear Vortex Motion in an Asymmetric Balance Shallow Water Model  

Science Conference Proceedings (OSTI)

This work extends asymmetric balance (AB) theory to the beta plane (?-AB). The physical problem examined is the motion of a coherent vortex on a beta plane in a finite depth fluid in the absence of an environmental steering flow. A useful ...

Michael T. Montgomery; J. Dominique Möller; Christopher T. Nicklas

1999-03-01T23:59:59.000Z

297

Indirect Combustion Noise: Experimental Investigation of the Vortex Sound Generation in a Choked  

E-Print Network (OSTI)

Indirect Combustion Noise: Experimental Investigation of the Vortex Sound Generation in a Choked-27 April 2012, Nantes, France 2315 #12;Combustion noise in gas turbines consists of direct noise related to the unsteady combustion process itself and indirect noise. As known, indirect noise is produced when entropy

Paris-Sud XI, Université de

298

Longitudinally Dependent Ozone Increase in the Antarctic Polar Vortex Revealed by Balloon and Satellite Observations  

Science Conference Proceedings (OSTI)

The horizontal structure of processes causing increases in ozone in the Antarctic polar vortex was examined using data measured in 2003 from an ozonesonde observation campaign at Syowa Station (39.6°E, 69.0°S) and from the Improved Limb ...

K. Sato; Y. Tomikawa; G. Hashida; T. Yamanouchi; H. Nakajima; T. Sugita

2009-06-01T23:59:59.000Z

299

Ozone Forecasts of the Stratospheric Polar Vortex–Splitting Event in September 2002  

Science Conference Proceedings (OSTI)

The Southern Hemisphere major warming event in September 2002 has led to a breakup of the vortex in the middle and higher stratosphere and to a corresponding splitting of the ozone hole. Daily 3D ozone forecasts, produced at the Royal Netherlands ...

Henk Eskes; Arjo Segers; Peter van Velthoven

2005-03-01T23:59:59.000Z

300

Genesis of the Goshen County, Wyoming, Tornado on 5 June 2009 during VORTEX2  

Science Conference Proceedings (OSTI)

The genesis of a strong and long-lived tornado observed during the second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2) in Goshen County, Wyoming, on 5 June 2009 is studied. Mobile radar, mobile mesonet, rawinsonde, and ...

Karen Kosiba; Joshua Wurman; Yvette Richardson; Paul Markowski; Paul Robinson; James Marquis

2013-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Stability of a Two-Layer Quasigeostrophic Vortex over Axisymmetric Localized Topography  

Science Conference Proceedings (OSTI)

The stability of a quasigeostrophic vortex over a radially symmetric topographic feature (elevation or depression) in a two-layer ocean on the f plane is examined. This article’s concern is with compensated vortices, that is, those in which the ...

E. S. Benilov

2005-01-01T23:59:59.000Z

302

Asymptotic and numerical analysis of an inviscid bounded vortex flow at low Mach number  

Science Conference Proceedings (OSTI)

The inviscid low Mach number compressible flow developing from a plane incompressible vortex with constant density in a bounded domain is studied. A reference solution for this model flow is obtained by two-time scale asymptotic development in the zero ... Keywords: Asymptotic development, Compressible low Mach number flow, Explicit Roe scheme, Implicit scheme, WENO and high-order-compact schemes

Anne Cadiou; Lionel Le Penven; Marc Buffat

2008-09-01T23:59:59.000Z

303

Generation and Stability of a Quasi-Permanent Vortex in the Lofoten Basin  

Science Conference Proceedings (OSTI)

In the Nordic seas the Lofoten Basin is a region of high mesoscale activity. The generation mechanism and the conditions for the stability of a quasi-permanent vortex in the center of the Lofoten Basin are studied with a high-resolution ocean ...

Armin Köhl

2007-11-01T23:59:59.000Z

304

Study of a Heavy Rain Vortex Formed over the Eastern Flank of the Tibetan Plateau  

Science Conference Proceedings (OSTI)

A case of the heavy rain vortex which occurred during the period 14–15 July 1979 is studied using a limited-area mesoscale numerical model. This is a representative example of a group of warm southwest vortices that often form over the eastern ...

Bin Wang; Isidoro Orlanski

1987-07-01T23:59:59.000Z

305

The Final Warming Date of the Antarctic Polar Vortex and Influences on its Interannual Variability  

Science Conference Proceedings (OSTI)

More than 40 years of radiosonde data from two Antarctic stations are examined for changes in the date of the final stratospheric warming that occurs each year as the vortex breaks up in spring/summer. A new measure of this date is derived that ...

Joanna D. Haigh; Howard K. Roscoe

2009-11-01T23:59:59.000Z

306

Aging memory and glassiness of a driven vortex , Guohong Li1  

E-Print Network (OSTI)

1 Aging memory and glassiness of a driven vortex system. Xu Du1 , Guohong Li1 , Eva Y. Andrei1 , M memory, aging and nonlinear-dynamics. Glasses[1-11], interfaces[12] and fractures are some examples[13 the deviation from equilibrium. After removing the force, the system ages with time and its subsequent response

Andrei, Eva Y.

307

The Second Verification of the Origins of Rotation in Tornadoes Experiment: VORTEX2  

Science Conference Proceedings (OSTI)

The second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2), which had its field phases in May and June of 2009 and 2010, was designed to explore i) the physical processes of tornadogenesis, maintenance, and demise; ii) the ...

Joshua Wurman; David Dowell; Yvette Richardson; Paul Markowski; Erik Rasmussen; Donald Burgess; Louis Wicker; Howard B. Bluestein

2012-08-01T23:59:59.000Z

308

Magnetic Materials  

Science Conference Proceedings (OSTI)

Oct 27, 2009 ... Extreme magnetic fields (>2 tesla), especially when combined with temperature, are being shown to revolutionize materials processing and ...

309

Correlated magnetic reversal in periodic stripe patterns  

Science Conference Proceedings (OSTI)

The magnetization reversal in a periodic magnetic stripe array has been studied with a combination of direct and reciprocal space methods: Kerr microscopy and polarized neutron scattering. Kerr images show that during magnetization reversal over a considerable magnetic-field range a ripple domain state occurs in the stripes with magnetization components perpendicular to the stripes. Quantitative analysis of polarized neutron specular reflection, Bragg diffraction, and off-specular diffuse scattering provides a detailed picture of the mean magnetization direction in the ripple domains as well as longitudinal and transverse fluctuations, and reveals a strong correlation of those components over a number of stripes.

Theis-Broehl, Katharina; Toperverg, Boris P.; Leiner, Vincent; Westphalen, Andreas; Zabel, Hartmut; McCord, Jeffrey; Rott, Karsten; Brueckl, Hubert [Department of Physics, Ruhr-University Bochum, 44780 Bochum (Germany); Leibniz Institute for Solid State and Materials Research Dresden, Institute for Metallic Materials, Helmholtzstr. 20, D-01169 Dresden (Germany); Department of Physics, University Bielefeld, Universitaetsstr. 25, 33615 Bielefeld (Germany)

2005-01-01T23:59:59.000Z

310

Magnetic filtration process, magnetic filtering material, and methods of forming magnetic filtering material  

SciTech Connect

The present invention provides magnetically responsive activated carbon, and a method of forming magnetically responsive activated carbon. The method of forming magnetically responsive activated carbon typically includes providing activated carbon in a solution containing ions of ferrite forming elements, wherein at least one of the ferrite forming elements has an oxidation state of +3 and at least a second of the ferrite forming elements has an oxidation state of +2, and increasing pH of the solution to precipitate particles of ferrite that bond to the activated carbon, wherein the activated carbon having the ferrite particles bonded thereto have a positive magnetic susceptibility. The present invention also provides a method of filtering waste water using magnetic activated carbon.

2013-10-08T23:59:59.000Z

311

Topological constraints in magnetic field relaxation  

E-Print Network (OSTI)

Stability and reconnection of magnetic fields play a fundamental role in natural and man-made plasma. In these applications the field's topology determines the stability of the magnetic field. Here I will describe the importance of one topology quantifier, the magnetic helicity, which impedes any free decay of the magnetic energy. Further constraints come from the fixed point index which hinders the field to relax into the Taylor state.

Candelaresi, Simon

2013-01-01T23:59:59.000Z

312

Magnetized baryonic matter in holographic QCD  

E-Print Network (OSTI)

We investigate the properties of the Sakai-Sugimoto model at finite magnetic field and baryon chemical potentials. We show that in a finite magnetic field, there exists a spatially homogeneous configuration carrying finite baryon number density. At low magnetic field and baryon chemical potential the equation of state of the matter coincides with that obtained from the chiral perturbation theory Lagrangian with an anomalous term. We discuss the behavior of the system at larger magnetic fields.

Ethan G. Thompson; Dam T. Son

2008-06-02T23:59:59.000Z

313

Verification of the Origins of Rotation in Tornadoes Experiment: VORTEX  

Science Conference Proceedings (OSTI)

This paper describes the Verification of the Origins of Rotation in Tornadoes Experiment planned for 1994 and 1995 to evaluate a set of hypotheses pertaining to tornadogenesis and tornado dynamics. Observations of state variables will be obtained ...

Erik N. Rasmussen; Jerry M. Straka; Robert Davies-Jones; Charles A. Doswell III; Frederick H. Carr; Michael D. Eilts; Donald R. MacGorman

1994-06-01T23:59:59.000Z

314

Particle filtering with Lagrangian data in a point vortex model  

E-Print Network (OSTI)

Particle filtering is a technique used for state estimation from noisy measurements. In fluid dynamics, a popular problem called Lagrangian data assimilation (LaDA) uses Lagrangian measurements in the form of tracer positions ...

Mitra, Subhadeep

2012-01-01T23:59:59.000Z

315

Magnetic nanotubes  

DOE Patents (OSTI)

A magnetic nanotube includes bacterial magnetic nanocrystals contacted onto a nanotube which absorbs the nanocrystals. The nanocrystals are contacted on at least one surface of the nanotube. A method of fabricating a magnetic nanotube includes synthesizing the bacterial magnetic nanocrystals, which have an outer layer of proteins. A nanotube provided is capable of absorbing the nanocrystals and contacting the nanotube with the nanocrystals. The nanotube is preferably a peptide bolaamphiphile. A nanotube solution and a nanocrystal solution including a buffer and a concentration of nanocrystals are mixed. The concentration of nanocrystals is optimized, resulting in a nanocrystal to nanotube ratio for which bacterial magnetic nanocrystals are immobilized on at least one surface of the nanotubes. The ratio controls whether the nanocrystals bind only to the interior or to the exterior surfaces of the nanotubes. Uses include cell manipulation and separation, biological assay, enzyme recovery, and biosensors.

Matsui, Hiroshi (Glen Rock, NJ); Matsunaga, Tadashi (Tokyo, JP)

2010-11-16T23:59:59.000Z

316

Superconducting Magnets  

NLE Websites -- All DOE Office Websites (Extended Search)

Mit Hilfe der Technologie supraleitender Magnete lassen sich in Mit Hilfe der Technologie supraleitender Magnete lassen sich in Ringbeschleunigern höhere Energien erreichen. Weil supraleitende Spulen keinen elektrischen Widerstand aufweisen, können damit stärkere Magnetfelder erzeugt werden. In normal leitenden Elektromagneten wird - wegen des elektrischen Widerstands der Drähte - die Spule aufgeheizt. Auf diese Weise geht sehr viel Energie in Form von Wärme verloren, was die Energiekosten dieser Magnete in die Höhe treibt. Supraleitende Spulen erlauben es, Magnete grosser Feldstärke unter günstigen Bedingungen zu betreiben und damit die Energiekosten zu senken. Durch den Einbau supraleitender Spulen in den Ringbeschleuniger von Fermilab konnte dessen Energie verdoppelt werden.Auch der im Bau befindliche "Large Hadron Collider" am CERN wird supraleitende Magnete

317

Tropical Cyclone Initialization with a Spherical High-Order Filter and an Idealized Three-Dimensional Bogus Vortex  

Science Conference Proceedings (OSTI)

A tropical cyclone initialization method with an idealized three-dimensional bogus vortex of an analytic empirical formula is presented for the track and intensity prediction. The procedure in the new method consists of four steps: the separation ...

In-Hyuk Kwon; Hyeong-Bin Cheong

2010-04-01T23:59:59.000Z

318

Variation in the Stratospheric Aerosol Associated with the North Cyclonic Polar Vortex as Measured by the SAM II Satellite Sensor  

Science Conference Proceedings (OSTI)

Aerosol extinction data obtained by the Stratospheric Aerosol Measurement II (SAM II) satellite instrument during the 1979/80 Northern Hemisphere winter season have been analyzed in relation to the cyclonic polar vortex. A synoptic approach has ...

G. S. Kent; C. R. Trepte; U. O. Farrukh; M. P. McCormick

1985-07-01T23:59:59.000Z

319

Convection-Allowing and Convection-Parameterizing Ensemble Forecasts of a Mesoscale Convective Vortex and Associated Severe Weather Environment  

Science Conference Proceedings (OSTI)

An analysis of a regional severe weather outbreak that was related to a mesoscale convective vortex (MCV) is performed. The MCV-spawning mesoscale convection system (MCS) formed in northwest Kansas along the southern periphery of a large cutoff ...

Adam J. Clark; William A. Gallus Jr.; Ming Xue; Fanyou Kong

2010-08-01T23:59:59.000Z

320

A Spatial Filter Approach to Evaluating the Role of Convection on the Evolution of a Mesoscale Vortex  

Science Conference Proceedings (OSTI)

A new spatial filter is proposed that exploits a spectral gap in power between the convective scale and the system (“vortex”) scale during tropical cyclone (TC) genesis simulations. Using this spatial separation, this study analyzes idealized ...

Glenn A. Creighton; Robert E. Hart; Philip Cunningham

2013-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Probabilistic Evaluation of the Dynamics and Predictability of the Mesoscale Convective Vortex of 10–13 June 2003  

Science Conference Proceedings (OSTI)

This study examines the dynamics and predictability of the mesoscale convective vortex (MCV) of 10–13 June 2003 through ensemble forecasting. The MCV of interest developed from a preexisting upper-level disturbance over the southwest United ...

Daniel P. Hawblitzel; Fuqing Zhang; Zhiyong Meng; Christopher A. Davis

2007-04-01T23:59:59.000Z

322

Observations of a Terrain-Forced Mesoscale Vortex and Canyon Drainage Flows along the Front Range of Colorado  

Science Conference Proceedings (OSTI)

Observations taken during the February 1991 Atmospheric Studies in Complex Terrain (ASCOT) Winter Validation Study are used to describe the wind field associated with a terrain-forced mesoscale vortex and thermally forced canyon drainage flows ...

David H. Levinson; Robert M. Banta

1995-07-01T23:59:59.000Z

323

Observations of a Squall Line and Its Near Environment Using High-Frequency Rawinsonde Launches during VORTEX2  

Science Conference Proceedings (OSTI)

Rawinsonde data were collected before and during passage of a squall line in Oklahoma on 15 May 2009 during the Second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2). Nine soundings were released within 3 h, allowing ...

George H. Bryan; Matthew D. Parker

2010-11-01T23:59:59.000Z

324

Contributions of the wall boundary layer to the formation of the counter-rotating vortex pair in transverse jets  

E-Print Network (OSTI)

Using high-resolution 3-D vortex simulations, this study seeks a mechanistic understanding of vorticity dynamics in transverse jets at a finite Reynolds number. A full no-slip boundary condition, rigorously formulated in ...

Schlegel, Fabrice

325

Turbulence process domination under the combined forcings of wind stress, the Langmuir vortex force, and surface cooling  

Science Conference Proceedings (OSTI)

Turbulence in the ocean surface layer is generated by time-varying combinations of destabilizing surface buoyancy flux, wind stress forcing, and wave forcing through a vortex force associated with the surface wave field. Observations of time- and ...

A. E. Gargett; C. E. Grosch

326

Purely magnetic spacetimes  

E-Print Network (OSTI)

Spacetimes in which the electric part of the Weyl tensor vanishes (relative to some timelike unit vector field) are said to be purely magnetic. Examples of purely magnetic spacetimes are known and are relatively easy to construct, if no restrictions are placed on the energy-momentum tensor. However it has long been conjectured that purely magnetic vacuum spacetimes (with or without a cosmological constant) do not exist. The history of this conjecture is reviewed and some advances made in the last year are described briefly. A generalisation of this conjecture first suggested for type D vacuum spacetimes by Ferrando and Saez is stated and proved in a number of special cases. Finally an approach to a general proof of the conjecture is described using the Newman-Penrose formalism based on a canonical null tetrad of the Weyl tensor.

Alan Barnes

2004-01-15T23:59:59.000Z

327

Heat transfer in a two-pass internally ribbed turbine blade coolant channel with cylindrical vortex generators  

DOE Green Energy (OSTI)

The effect of vortex generators on the mass (heat) transfer from the ribbed passage of a two pass turbine blade coolant channel is investigated with the intent of optimizing the vortex generator geometry so that significant enhancements in mass/heat transfer can be achieved. In the experimental configuration considered, ribs are mounted on two opposite walls; all four walls along each pass are active and have mass transfer from their surfaces but the ribs are non-participating. Mass transfer measurements, in the form of Sherwood number ratios, are made along the centerline and in selected inter-rib modules. Results are presented for Reynolds number in the range of 5,000 to 40,000, pitch to rib height ratios of 10.5 and 21, and vortex generator-rib spacing to rib height ratios of 0.55, and 1.5. Centerline and spanwise averaged Sherwood number ratios are presented along with contours of the Sherwood number ratios. Results indicate that the vortex generators induce substantial increases in the local mass transfer rates, particularly along the side walls, and modest increases in the average mass transfer rates. The vortex generators have the effect of making the inter-rib profiles along the ribbed walls more uniform. Along the side walls, horse-shoe vortices that characterize the vortex generator wake are associated with significant mass transfer enhancements. The wake effects and the levels of enhancement decrease somewhat with increasing Reynolds number and decreasing pitch.

Hibbs, R.; Acharya, S.; Chen, Y. [Louisiana State Univ., Baton Rouge, LA (United States)] [and others

1995-12-31T23:59:59.000Z

328

Evaluation of Suspected Steady-State Magnetic Induction by a 345-kV Double-Circuit Transmission Line onto Railroad Track  

Science Conference Proceedings (OSTI)

CenterPoint Energy operates a double circuit 345-kV transmission line north of Houston that parallels the Burlington Northern Santa Fe Railroad (BNSF) for approximately 15 miles. The railroad is experiencing elevated steady-state 60-Hz voltage in the parallel exposure. AC voltages and currents in railroad track can come from many sources. And, railroad systems can withstand reasonable amounts of this electromagnetic interference (EMI) without problems. When problems with EMI on a railroad do appear, it i...

2008-11-12T23:59:59.000Z

329

Nuclear Magnetic Resonance Laboratory  

Science Conference Proceedings (OSTI)

Nuclear Magnetic Resonance Laboratory. ... A 600 MHz Nuclear Magnetic Resonance Spectrometer. Analytical Data Compilation Reference Materials. ...

2012-10-01T23:59:59.000Z

330

Visualizing Spacetime Curvature via Frame-Drag Vortexes and Tidal Tendexes II. Stationary Black Holes  

E-Print Network (OSTI)

When one splits spacetime into space plus time, the Weyl curvature tensor (which equals the Riemann tensor in vacuum) splits into two spatial, symmetric, traceless tensors: the tidal field $E$, which produces tidal forces, and the frame-drag field $B$, which produces differential frame dragging. In recent papers, we and colleagues have introduced ways to visualize these two fields: tidal tendex lines (integral curves of the three eigenvector fields of $E$) and their tendicities (eigenvalues of these eigenvector fields); and the corresponding entities for the frame-drag field: frame-drag vortex lines and their vorticities. These entities fully characterize the vacuum Riemann tensor. In this paper, we compute and depict the tendex and vortex lines, and their tendicities and vorticities, outside the horizons of stationary (Schwarzschild and Kerr) black holes; and we introduce and depict the black holes' horizon tendicity and vorticity (the normal-normal components of $E$ and $B$ on the horizon). For Schwarzschil...

Zhang, Fan; Nichols, David A; Chen, Yanbei; Lovelace, Geoffrey; Matthews, Keith D; Owen, Robert; Thorne, Kip S

2012-01-01T23:59:59.000Z

331

Effect of NO on extinction and re-ignition of vortex-perturbed hydrogen flames.  

DOE Green Energy (OSTI)

The catalytic effect of nitric oxide (NO) on the dynamics of extinction and re-ignition of a vortex-perturbed non-premixed hydrogen-air flame is studied in a counterflow burner. A diffusion flame is established with counterflowing streams of nitrogen-diluted hydrogen at ambient temperature and air heated to a range of temperatures that brackets the auto-ignition temperature. Localized extinction is induced by impulsively driving a fuel-side toroidal vortex into the steady flame, and the recovery of the extinguished region is monitored by planar laser-induced fluorescence (PLIF) of the hydroxyl radical (OH). The dynamics of flame recovery depend on the air temperature and fuel concentration, and four different recovery modes are identified. These modes involve combinations of edge-flame propagation and the expansion of an auto-ignition kernel that forms within the extinguished region. The addition of a small amount of NO significantly alters the re-ignition process by shifting the balance between chain-termination and chain-propagation reactions to enhance auto-ignition. The ignition enhancement by this catalytic effect causes a shift in the conditions that govern the recovery modes. In addition, the effects of NO concentration and vortex strength on the flame recovery are examined. Direct numerical simulations of the flame-vortex interaction with and without NO doping show how the small amount of OH produced by NO-catalyzed reactions has a significant impact on the development of an auto-ignition kernel. This joint experimental and numerical study provides detailed insight into the interaction between transient flows and ignition processes.

Yoo, Chun Sang; Chen, Jacqueline H.; Frank, Jonathan H.; Lee, Uen Do (KITECH, Cheonan, Chungnam, South Korea)

2009-01-01T23:59:59.000Z

332

Numerical evidence of breaking of vortex lines in an ideal fluid  

E-Print Network (OSTI)

Emergence of singularity of vorticity at a single point, not related to any symmetry of the initial distribution, has been demonstrated numerically for the first time. Behavior of the maximum of vorticity near the point of collapse closely follows the dependence 1/(t0-t), where t0 is the time of collapse. This agrees with the interpretation of collapse in an ideal incompressible fluid as of the process of vortex lines breaking.

Kuznetsov, E A; Zheligovsky, V A

2001-01-01T23:59:59.000Z

333

Tripolar vortex formation in dense quantum plasma with ion-temperature-gradients  

SciTech Connect

We have derived system of nonlinear equations governing the dynamics of low-frequency electrostatic toroidal ion-temperature-gradient mode for dense quantum magnetoplasma. For some specific profiles of the equilibrium density, temperature, and ion velocity gradients, the nonlinear equations admit a stationary solution in the form of a tripolar vortex. These results are relevant to understand nonlinear structure formation in dense quantum plasmas in the presence of equilibrium ion-temperature and density gradients.

Qamar, Anisa; Ata-ur-Rahman [Institute of Physics and Electronics, University of Peshawar, Khyber Pakhtoon Khwa 25000 (Pakistan); National Center for Physics Shahdrah Valley Road, Islamabad 44000 (Pakistan); Mirza, Arshad M. [Theoretical Plasma Physics Group, Physics Department, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

2012-05-15T23:59:59.000Z

334

Visualizing Spacetime Curvature via Frame-Drag Vortexes and Tidal Tendexes II. Stationary Black Holes  

E-Print Network (OSTI)

When one splits spacetime into space plus time, the Weyl curvature tensor (which equals the Riemann tensor in vacuum) splits into two spatial, symmetric, traceless tensors: the tidal field $E$, which produces tidal forces, and the frame-drag field $B$, which produces differential frame dragging. In recent papers, we and colleagues have introduced ways to visualize these two fields: tidal tendex lines (integral curves of the three eigenvector fields of $E$) and their tendicities (eigenvalues of these eigenvector fields); and the corresponding entities for the frame-drag field: frame-drag vortex lines and their vorticities. These entities fully characterize the vacuum Riemann tensor. In this paper, we compute and depict the tendex and vortex lines, and their tendicities and vorticities, outside the horizons of stationary (Schwarzschild and Kerr) black holes; and we introduce and depict the black holes' horizon tendicity and vorticity (the normal-normal components of $E$ and $B$ on the horizon). For Schwarzschild and Kerr black holes, the horizon tendicity is proportional to the horizon's intrinsic scalar curvature, and the horizon vorticity is proportional to an extrinsic scalar curvature. We show that, for horizon-penetrating time slices, all these entities ($E$, $B$, the tendex lines and vortex lines, the lines' tendicities and vorticities, and the horizon tendicities and vorticities) are affected only weakly by changes of slicing and changes of spatial coordinates, within those slicing and coordinate choices that are commonly used for black holes. [Abstract is abbreviated.

Fan Zhang; Aaron Zimmerman; David A. Nichols; Yanbei Chen; Geoffrey Lovelace; Keith D. Matthews; Robert Owen; Kip S. Thorne

2012-08-15T23:59:59.000Z

335

Learning About Magnets!  

NLE Websites -- All DOE Office Websites (Extended Search)

the the National High Magnetic Field Laboratory Learning About Name A magnet is a material or object that creates a magnetic fi eld. This fi eld is invisible, but it creates a force that can "attract" or "repel" other magnets and magnetic materials, like iron or nickel. What is a Magnet? This bar magnet is a permanent magnet. Permanent magnets can be found in the Earth as rocks and metals. Magnets have

336

High Field Magnetic Resonance Facility  

NLE Websites -- All DOE Office Websites (Extended Search)

HFMRF Overview HFMRF Overview Section 2-3-1 High Field Magnetic Resonance Facility The High Field Magnetic Resonance Facility (HFMRF) focuses a significant portion of its research on developing a fundamental, molecular-level understanding of biochemical and biological systems and their response to environmental effects. A secondary focus is materials science, including catalysis and chemical mechanisms and processes. Staff and science consultants within this facility offer expertise in the areas of structural biology, solid-state materials characterization, and magnetic resonance imaging (MRI) techniques. Research activities in the HFMRF include: * structure determination of large molecular assemblies such as protein-DNA (normal and damaged DNA) and protein-RNA complexes

337

Neutrino magnetic moment in a magnetized plasma  

E-Print Network (OSTI)

The contribution of a magnetized plasma to the neutrino magnetic moment is calculated. It is shown that only part of the additional neutrino energy in magnetized plasma connecting with its spin and magnetic field strength defines the neutrino magnetic moment. It is found that the presence of magnetized plasma does not lead to the considerable increase of the neutrino magnetic moment in contrast to the results presented in literature previously.

N. V. Mikheev; E. N. Narynskaya

2010-11-08T23:59:59.000Z

338

Magnetohydrodynamic evolution of magnetic skeletons  

E-Print Network (OSTI)

The heating of the solar corona is likely to be due to reconnection of the highly complex magnetic field that threads throughout its volume. We have run a numerical experiment of an elementary interaction between the magnetic field of two photospheric sources in an overlying field that represents a fundamental building block of the coronal heating process. The key to explaining where, how and how much energy is released during such an interaction is to calculate the resulting evolution of the magnetic skeleton. A skeleton is essentially the web of magnetic flux surfaces (called separatrix surfaces) that separate the coronal volume into topologically distinct parts. For the first time the skeleton of the magnetic field in a 3D numerical MHD experiment is calculated and carefully analysed, as are the ways in which it bifurcates into different topologies. A change in topology normally changes the number of magnetic reconnection sites. In our experiment, the magnetic field evolves through a total of six distinct topologies. Initially, no magnetic flux joins the two sources. Then a new type of bifurcation, called a global double-separator bifurcation, takes place: this bifurcation is likely to be one of the main ways in which new separators are created in the corona (separators are field lines at which 3D reconnection takes place). This is the first of five bifurcations in which the skeleton becomes progressively more complex before simplifying. Surprisingly, for such a simple initial state, at the peak of complexity there are five separators and eight flux domains present.

Andrew L. Haynes; Clare E. Parnell; Klaus Galsgaard; Eric R. Priest

2007-02-22T23:59:59.000Z

339

Dynamics of topological light states in spiraling structures  

E-Print Network (OSTI)

We expose a mechanism for the dynamical generation and control of light states with diverse topologies in spiraling guiding structures. Specifically, we show that spiraling shallow refractive index landscapes induce coupling and periodic energy exchange between states with different topological charges. Such a resonant effect enables excitation of optical vortices by vortex-free inputs and allows the output topological charge of the beam to be controlled. The presence of nonlinearity results in a strong asymmetrization of the resonant curves and a shift of the resonant frequencies. Resonant vortex dynamic generation, including revivals, is shown to be possible not only in waveguides mediated by total internal reflection but also in Bragg-guiding hollow-core geometries.

Kartashov, Yaroslav V; Torner, Lluis

2013-01-01T23:59:59.000Z

340

Soft magnetic lithography and giant magnetoresistance in superconducting/ferromagnetic hybrids.  

Science Conference Proceedings (OSTI)

We demonstrate an approach to create a tunable pinning potential in a superconducting/ferromagnetic (SC/FM) hybrid, allowing the switching of their electronic properties through the application of a small magnetic field. Using direct magneto-optical imaging, macroscopic transport, and magnetic measurements, we show that the alignment of stripe domains in the ferromagnet provides a remarkable directionality for the superconducting vortex motion. An analysis of the anisotropic flux motion demonstrates a substantial critical current anisotropy in the superconductor. The possibility of aligning stable lattices of stripe domains in select directions using in-plane magnetic fields allows the realization of soft magnetic lithography for efficient manipulation of supercurrent flow in SC/FM bilayers. Furthermore, in our samples we observed a pronounced magnetoresistance effect yielding 4 orders of magnitude resistivity change in a few millitesla in-plane field.

Vlasko-Vlasov, V.; Welp, U.; Imre, A.; Rosenmann, D.; Pearson, J.; Kwok, W. K.

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Magnetization Characterization Laboratory  

Science Conference Proceedings (OSTI)

... use of magnetic materials for motors, generators, transformers ... all depend on the specific magnetic characteristics of ... For example, a magnet used in ...

2012-10-23T23:59:59.000Z

342

SUPERCONDUCTING MAGNETIC ENERGY STORAGE  

E-Print Network (OSTI)

Scale Superconducting Magnetic Energy Storage Plant", IEEEfor SlIperconducting Magnetic Energy Storage Unit", inSuperconducting Magnetic Energy Storage Plant, Advances in

Hassenzahl, W.

2011-01-01T23:59:59.000Z

343

MAGNETIC GRID  

DOE Patents (OSTI)

An electronic grid is designed employing magnetic forces for controlling the passage of charged particles. The grid is particularly applicable to use in gas-filled tubes such as ignitrons. thyratrons, etc., since the magnetic grid action is impartial to the polarity of the charged particles and, accordingly. the sheath effects encountered with electrostatic grids are not present. The grid comprises a conductor having sections spaced apart and extending in substantially opposite directions in the same plane, the ends of the conductor being adapted for connection to a current source.

Post, R.F.

1960-08-01T23:59:59.000Z

344

Electronic Structure and Magnetism in Diluted Magnetic Semiconductors  

NLE Websites -- All DOE Office Websites (Extended Search)

Electronic Structure and Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Print Wednesday, 29 November 2006 00:00 The possibility of using electrons' spins in addition to their charge in information technology has created much enthusiasm for a new field of electronics popularly known as "spintronics." An intensely studied approach to obtaining spin-polarized carriers for data-storage devices is the use of diluted magnetic semiconductors created by doping ions like Mn, Fe, or Co having a net spin into a semiconducting host such as GaAs, ZnO, or GaN. The interaction among these spins leads to ferromagnetic order at low temperatures, which is necessary to create spin-polarized carriers. A research team working at ALS Beamline 4.0.2 and European Synchrotron Radiation Facility Beamline ID8 made a big leap forward in clarifying the microscopic picture of magnetism and anisotropy in Mn-doped GaAs by resolving localized and hybridized d states using angle-dependent x-ray magnetic circular dichroism (XMCD) measurements.

345

Electronic Structure and Magnetism in Diluted Magnetic Semiconductors  

NLE Websites -- All DOE Office Websites (Extended Search)

Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Print Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Print The possibility of using electrons' spins in addition to their charge in information technology has created much enthusiasm for a new field of electronics popularly known as "spintronics." An intensely studied approach to obtaining spin-polarized carriers for data-storage devices is the use of diluted magnetic semiconductors created by doping ions like Mn, Fe, or Co having a net spin into a semiconducting host such as GaAs, ZnO, or GaN. The interaction among these spins leads to ferromagnetic order at low temperatures, which is necessary to create spin-polarized carriers. A research team working at ALS Beamline 4.0.2 and European Synchrotron Radiation Facility Beamline ID8 made a big leap forward in clarifying the microscopic picture of magnetism and anisotropy in Mn-doped GaAs by resolving localized and hybridized d states using angle-dependent x-ray magnetic circular dichroism (XMCD) measurements.

346

Electronic Structure and Magnetism in Diluted Magnetic Semiconductors  

NLE Websites -- All DOE Office Websites (Extended Search)

Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Print Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Print The possibility of using electrons' spins in addition to their charge in information technology has created much enthusiasm for a new field of electronics popularly known as "spintronics." An intensely studied approach to obtaining spin-polarized carriers for data-storage devices is the use of diluted magnetic semiconductors created by doping ions like Mn, Fe, or Co having a net spin into a semiconducting host such as GaAs, ZnO, or GaN. The interaction among these spins leads to ferromagnetic order at low temperatures, which is necessary to create spin-polarized carriers. A research team working at ALS Beamline 4.0.2 and European Synchrotron Radiation Facility Beamline ID8 made a big leap forward in clarifying the microscopic picture of magnetism and anisotropy in Mn-doped GaAs by resolving localized and hybridized d states using angle-dependent x-ray magnetic circular dichroism (XMCD) measurements.

347

Questions about Magnets  

NLE Websites -- All DOE Office Websites (Extended Search)

off just the north (or just the south) end of a magnet? Are magnets stronger than gravity? Hold a magnet in the air. Place a nail against it. The magnet holds the nail up...

348

Reversing the Circulation of Magnetic Vortices  

NLE Websites -- All DOE Office Websites (Extended Search)

Reversing the Circulation of Magnetic Vortices Print Reversing the Circulation of Magnetic Vortices Print In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny magnetic whirl has a polarity that can point up or down and a circulation that can be oriented clockwise or counterclockwise. Previous studies have shown that the polarity can be flipped on command. Now, using time-resolved magnetic soft x-ray microscopy at the ALS, researchers have shown for the first time how to use pulsed magnetic fields to reverse the circulation.

349

Reversing the Circulation of Magnetic Vortices  

NLE Websites -- All DOE Office Websites (Extended Search)

Reversing the Circulation of Magnetic Vortices Print Reversing the Circulation of Magnetic Vortices Print In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny magnetic whirl has a polarity that can point up or down and a circulation that can be oriented clockwise or counterclockwise. Previous studies have shown that the polarity can be flipped on command. Now, using time-resolved magnetic soft x-ray microscopy at the ALS, researchers have shown for the first time how to use pulsed magnetic fields to reverse the circulation.

350

Reversing the Circulation of Magnetic Vortices  

NLE Websites -- All DOE Office Websites (Extended Search)

Reversing the Circulation of Magnetic Vortices Print Reversing the Circulation of Magnetic Vortices Print In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny magnetic whirl has a polarity that can point up or down and a circulation that can be oriented clockwise or counterclockwise. Previous studies have shown that the polarity can be flipped on command. Now, using time-resolved magnetic soft x-ray microscopy at the ALS, researchers have shown for the first time how to use pulsed magnetic fields to reverse the circulation.

351

Reversing the Circulation of Magnetic Vortices  

NLE Websites -- All DOE Office Websites (Extended Search)

Reversing the Circulation of Reversing the Circulation of Magnetic Vortices Reversing the Circulation of Magnetic Vortices Print Wednesday, 31 July 2013 00:00 In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny magnetic whirl has a polarity that can point up or down and a circulation that can be oriented clockwise or counterclockwise. Previous studies have shown that the polarity can be flipped on command. Now, using time-resolved magnetic soft x-ray microscopy at the ALS, researchers have shown for the first time how to use pulsed magnetic fields to reverse the circulation.

352

Reversing the Circulation of Magnetic Vortices  

NLE Websites -- All DOE Office Websites (Extended Search)

Reversing the Circulation of Magnetic Vortices Print Reversing the Circulation of Magnetic Vortices Print In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny magnetic whirl has a polarity that can point up or down and a circulation that can be oriented clockwise or counterclockwise. Previous studies have shown that the polarity can be flipped on command. Now, using time-resolved magnetic soft x-ray microscopy at the ALS, researchers have shown for the first time how to use pulsed magnetic fields to reverse the circulation.

353

Reversing the Circulation of Magnetic Vortices  

NLE Websites -- All DOE Office Websites (Extended Search)

Reversing the Circulation of Magnetic Vortices Print Reversing the Circulation of Magnetic Vortices Print In magnetic media, information is stored in binary form-one or zero, depending on which way the electronic spins are aligned in a given section of the medium. Recently, however, magnetic vortices have drawn scientists toward a new possibility: multibit storage in which each logic unit has four states instead of two and can store twice the information. Each tiny magnetic whirl has a polarity that can point up or down and a circulation that can be oriented clockwise or counterclockwise. Previous studies have shown that the polarity can be flipped on command. Now, using time-resolved magnetic soft x-ray microscopy at the ALS, researchers have shown for the first time how to use pulsed magnetic fields to reverse the circulation.

354

Interconversion of dark soliton and Josephson vortex in a quasi-1D long Bose Josephson junction  

E-Print Network (OSTI)

Dark soliton (DS) and Josephson vortex (JV) in quasi-1D long Bose Josephson junction (BJJ) can be interconverted by tuning Josephson coupling. Rates of the interconversion as well as of the thermally activated phase-slip effect, resulting in the JV switching its vorticity, have been evaluated. The role of quantum phase-slip in creating superposition of JVs with opposite vorticities as a qubit is discussed as well. Utilization of the JV for controlled and coherent transfer of atomic Bose-Einstein condensate (BEC) is suggested.

V. M. Kaurov; A. B. Kuklov

2003-12-03T23:59:59.000Z

355

Campbell penetration depth of a superconductor in the critical state.  

SciTech Connect

The magnetic penetration depth {lambda}(T,H{sub J}) was measured in the presence of a slowly relaxing supercurrent j. In single crystal Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} below approximately 25 K, {lambda}(T,H{sub J}) is strongly hysteretic. We propose that the irreversibility arises from a shift of the vortex position within its pinning well as j changes. The Campbell length depends upon the ratio j/j{sub c} where j{sub c} is the critical current defined through the Labusch parameter. Similar effects were observed in other cuprates and in an organic superconductor.

Prozorov, R.; Giannetta, R. W.; Tamegai, T.; Schlueter, J.; Kini, A. M.; Fournier, P.; Greene, R. L.; Materials Science Division; Univ. of Illinois; Univ. of South Carolina; Univ. of Tokyo; Univ. of Sherbrooke; Univ. of Maryland

2003-05-01T23:59:59.000Z

356

magnets2  

NLE Websites -- All DOE Office Websites (Extended Search)

II II Painless Physics Articles BEAM COOLING August 2, 1996 By Leila Belkora, Office of Public Affairs ACCELERATION August 16, 1996 By Dave Finley, Accelerator Division Head RF August 30, 1996 By Pat Colestock, Accelerator Division FIXED TARGET PHYSICS September 20, 1996 By Peter H. Garbincius, Physics Section FIXED TARGET PHYSICS PART DEUX October 16, 1996 By Peter H. Garbincius, Physics Section and Leila Belkora, Office of Public Affaris CROSS SECTION November 1, 1996 By Doreen Wackeroth, Theoretical Physics Edited by Leila Belkora, Office of Public Affaris MAGNETS PART I November 15, 1996 By Hank Glass, Technical Support Section Edited by Donald Sena, Office of Public Affairs MAGNETS PART II January 10, 1997 By Hank Glass, Technical Support Section Edited by Donald Sena, Office of Public Affairs

357

Novel nuclear magnetic resonance techniques for studying biological molecules  

E-Print Network (OSTI)

parameters by solid-state nuclear magnetic resonance." J.and R. V. Pound. "Nuclear audiofrequency spectroscopy byresonant heating of the nuclear spin system." Phys. Rev. ,

Laws, David D.

2010-01-01T23:59:59.000Z

358

Advanced Magnetic Materials for Next Generation Data Storage ...  

Science Conference Proceedings (OSTI)

All Solid State 2-Dimensional Li Battery · Alloy Design and ... Rare-Earth Magnets · Challenge to Development of Diamond Power Devices for Saving Energy.

359

Magnetic Reconnection  

SciTech Connect

We review the fundamental physics of magnetic reconnection in laboratory and space plasmas, by discussing results from theory, numerical simulations, observations from space satellites, and the recent results from laboratory plasma experiments. After a brief review of the well-known early work, we discuss representative recent experimental and theoretical work and attempt to interpret the essence of significant modern findings. In the area of local reconnection physics, many significant findings have been made with regard to two- uid physics and are related to the cause of fast reconnection. Profiles of the neutral sheet, Hall currents, and the effects of guide field, collisions, and micro-turbulence are discussed to understand the fundamental processes in a local reconnection layer both in space and laboratory plasmas. While the understanding of the global reconnection dynamics is less developed, notable findings have been made on this issue through detailed documentation of magnetic self-organization phenomena in fusion plasmas. Application of magnetic reconnection physics to astrophysical plasmas is also brie y discussed.

Masaaki Yamada, Russell Kulsrud and Hantao Ji

2009-09-17T23:59:59.000Z

360

On the dynamics of flame edges in diffusion-flame/vortex interactions  

Science Conference Proceedings (OSTI)

We analyze the local flame extinction and reignition of a counterflow diffusion flame perturbed by a laminar vortex ring. Local flame extinction leads to the appearance of flame edges separating the burning and extinguished regions of the distorted mixing layer. The dynamics of these edges is modeled based on previous numerical results, with heat release effects fully taken into account, which provide the propagation velocity of triple and edge flames in terms of the upstream unperturbed value of the scalar dissipation. The temporal evolution of the mixing layer is determined using the classical mixture fraction approach, with both unsteady and curvature effects taken into account. Although variable density effects play an important role in exothermic reacting mixing layers, in this paper the description of the mixing layer is carried out using the constant density approximation, leading to a simplified analytical description of the flow field. The mathematical model reveals the relevant nondimensional parameters governing diffusion-flame/vortex interactions and provides the parameter range for the more relevant regime of local flame extinction followed by reignition via flame edges. Despite the simplicity of the model, the results show very good agreement with previously published experimental results. (author)

Hermanns, Miguel; Linan, Amable [Departamento de Motopropulsion y Termofluidodinamica, Universidad Politecnica de Madrid, Pza. Cardenal Cisneros 3, 28040 Madrid (Spain); Vera, Marcos [Area de Mecanica de Fluidos, Universidad Carlos III de Madrid, 28911 Leganes (Spain)

2007-04-15T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Combustion of pulverized coal in vortex structures. Final report, October 1, 1993--December 31, 1995  

Science Conference Proceedings (OSTI)

The objectives of the project were: (i) to understand the effects of heating one of the streams on the characteristics of shear layers, (ii) to investigate the changes in the characteristics of large scale vortex structures in the shear layer caused by the introduction of inert solid particles in one of the feed streams; (iii) to understand the effects of pyrolyzing solids on the shear layer behavior; and (iv) to study the effects of combustion of particles and their pyrolysis products on the shear layer structure, heat release rate, and pollutant emission characteristics. An experimental facility for generating two-dimensional shear layers containing vortex structures has been designed and fabricated. The experimental facility is essentially a low speed wind tunnel designed to (i) provide two gas streams, initially with uniform velocity profiles and isotropic turbulence, mixing at the end of a splitter plate, (ii) introduce vorticity by passively perturbing one of the streams, (iii) allow heating of one of the streams to temperatures high enough to cause pyrolysis of coal particles, and (iv) provide a natural gas flame in one of the streams to result in ignition and burning of coal particles.

Gollahalli, S.R.; Butuk, N.

1996-03-01T23:59:59.000Z

362

Lensless Imaging of Magnetic Nanostructures  

NLE Websites -- All DOE Office Websites (Extended Search)

Lensless Imaging of Magnetic Lensless Imaging of Magnetic Nanostructures Lensless Imaging of Magnetic Nanostructures Print Wednesday, 28 March 2012 00:00 Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the ALS's soft x-rays have enabled scientists to apply lensless x-ray imaging for the first time to nanometer-scale magnetic structures in an alloy. Many Ways To See You open your eyes and detect the light rays streaming through your bedroom window (transmission), illuminating your socks on the floor (scattering). You put on your glasses (refraction) to detect the state of your image in the mirror (reflection). If you are an ALS scientist, perhaps you go to work and shine some x-ray light on a crystal to detect the arrangement of the atoms in the crystal (diffraction). Now, thanks to Turner et al., you can also shine some x-ray light on a magnetic sample to detect the arrangement of its electron spins through a method known as lensless imaging. This last example is an equally valid way to "see," but instead of using windows, lenses, or mirrors to manipulate light and construct an image, mathematical formulas are used to describe the effects that particles and fields in the sample have on the light. These formulas have always contained terms that relate to the electron spin of magnetic atoms, but they were previously ignored. Using the full formula allows for the determination of not only crystal structure, but magnetic spin distribution and orientation as well, with a spatial resolution limited only by the wavelength of x-rays used. This promising method can be used at any coherent light source, including modern x-ray free-electron lasers, where ultrashort pulses would freeze-frame magnetic changes, offering the potential for imaging in unprecedented detail the structure and motion of boundaries between regions with different magnetic orientation.

363

Vortex creep and critical current densities in superconducting (Ba,K)Fe2As2 single crystals  

Science Conference Proceedings (OSTI)

The surprisingly rapid relaxation of the sustainable current density in the critical state of single-crystalline Ba1?xKxFe2As2 is investigated for magnetic fields oriented parallel to the c axis and to the ab plane, respectively. Due to the inadequacy of standard analysis procedures developed for flux creep in the high-temperature superconducting cuprates, we develop a simple, straightforward data treatment technique that reveals the creep mechanism and the creep exponent ?. At low magnetic fields, below the second magnetization peak, ? varies only slightly as a function of temperature and magnetic flux density B. From the data, we determine the temperature and field dependencies of the effective activation barrier for creep. At low temperatures, the measured current density approaches the zero-temperature critical current density (in the absence of creep) to within a factor 2, thus lending credence to earlier conclusions drawn with respect to the pinning mechanism. The comparable values of the experimental screening current density and the zero-temperature critical current density reveal the limited usefulness of the widely used “interpolation formula.”

Konczykowski, M.; van Der Beek, C.J.; Tanatar, Makariy A.; Luo, Huiqian; Wang, Zhaosheng; Shen, Bing; Wen, Hai Hu; Prozorov, Ruslan

2012-07-13T23:59:59.000Z

364

Optimizing the WSR-88D Mesocyclone/Tornadic Vortex Signature Algorithm Using WATADS—A Case Study  

Science Conference Proceedings (OSTI)

A tornado outbreak occurred in east-central Minnesota around 0000 UTC 22 July 1995, within 80 km of the KMPX WSR-88D, at the Minneapolis–Chanhassen Weather Service Forecast Office (WSFO). The WSR-88D Mesocyclone/Tornadic Vortex Signature ...

Gregory A. Tipton; Eric D. Howieson; John A. Margraf; Robert R. Lee

1998-06-01T23:59:59.000Z

365

ECMWF Analyses and Forecasts of Stratospheric Winter Polar Vortex Breakup: September 2002 in the Southern Hemisphere and Related Events  

Science Conference Proceedings (OSTI)

Breakup of the polar stratospheric vortex in the Northern Hemisphere is an event that is known to be predictable for up to a week or so ahead. This is illustrated using data from the 45-yr ECMWF Re-Analysis (ERA-40) for the sudden warmings of ...

Adrian Simmons; Mariano Hortal; Graeme Kelly; Anthony McNally; Agathe Untch; Sakari Uppala

2005-03-01T23:59:59.000Z

366

Tracking Waves and Vortex Nucleation in Excitable Systems with Anomalous Dispersion N. Manz, C.T. Hamik, and O. Steinbock  

E-Print Network (OSTI)

Tracking Waves and Vortex Nucleation in Excitable Systems with Anomalous Dispersion N. Manz, C of the underlying anomalous dispersion relation. DOI: 10.1103/PhysRevLett.92.248301 PACS numbers: 82.40.Ck, 05.45.­a and physicochemical systems [1,2]. Important examples include neuronal and cardiac tissue as well as gas discharge

Steinbock, Oliver

367

Vortex Rossby Waves in a Numerically Simulated Tropical Cyclone. Part II: The Role in Tropical Cyclone Structure and Intensity Changes  

Science Conference Proceedings (OSTI)

In Part I, the author analyzed the asymmetric structure in the inner core of a numerically simulated tropical cyclone and found that the asymmetry near the eyewall in the mid–lower troposphere is dominated by wavenumber-1 and -2 vortex Rossby ...

Yuqing Wang

2002-04-01T23:59:59.000Z

368

Soliton trains and vortex streets as a form of Cerenkov radiation in trapped Bose-Einstein condensates  

Science Conference Proceedings (OSTI)

We numerically study the nucleation of gray solitons and vortex-antivortex pairs created by a moving impurity in, respectively, 1D and 2D Bose-Einstein condensates (BECs) confined by a parabolic potential. The simulations emulate the motion of a localized ... Keywords: Bose-Einstein condensation, Matter waves, Nucleation, Solitons, Vortices

R. Carretero-González; P. G. Kevrekidis; D. J. Frantzeskakis; B. A. Malomed; S. Nandi; A. R. Bishop

2007-03-01T23:59:59.000Z

369

Lensless Imaging of Magnetic Nanostructures  

NLE Websites -- All DOE Office Websites (Extended Search)

Lensless Imaging of Magnetic Nanostructures Print Lensless Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the ALS's soft x-rays have enabled scientists to apply lensless x-ray imaging for the first time to nanometer-scale magnetic structures in an alloy. Many Ways To See You open your eyes and detect the light rays streaming through your bedroom window (transmission), illuminating your socks on the floor (scattering). You put on your glasses (refraction) to detect the state of your image in the mirror (reflection). If you are an ALS scientist, perhaps you go to work and shine some x-ray light on a crystal to detect the arrangement of the atoms in the crystal (diffraction). Now, thanks to Turner et al., you can also shine some x-ray light on a magnetic sample to detect the arrangement of its electron spins through a method known as lensless imaging. This last example is an equally valid way to "see," but instead of using windows, lenses, or mirrors to manipulate light and construct an image, mathematical formulas are used to describe the effects that particles and fields in the sample have on the light. These formulas have always contained terms that relate to the electron spin of magnetic atoms, but they were previously ignored. Using the full formula allows for the determination of not only crystal structure, but magnetic spin distribution and orientation as well, with a spatial resolution limited only by the wavelength of x-rays used. This promising method can be used at any coherent light source, including modern x-ray free-electron lasers, where ultrashort pulses would freeze-frame magnetic changes, offering the potential for imaging in unprecedented detail the structure and motion of boundaries between regions with different magnetic orientation.

370

Lensless Imaging of Magnetic Nanostructures  

NLE Websites -- All DOE Office Websites (Extended Search)

Lensless Imaging of Magnetic Nanostructures Print Lensless Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the ALS's soft x-rays have enabled scientists to apply lensless x-ray imaging for the first time to nanometer-scale magnetic structures in an alloy. Many Ways To See You open your eyes and detect the light rays streaming through your bedroom window (transmission), illuminating your socks on the floor (scattering). You put on your glasses (refraction) to detect the state of your image in the mirror (reflection). If you are an ALS scientist, perhaps you go to work and shine some x-ray light on a crystal to detect the arrangement of the atoms in the crystal (diffraction). Now, thanks to Turner et al., you can also shine some x-ray light on a magnetic sample to detect the arrangement of its electron spins through a method known as lensless imaging. This last example is an equally valid way to "see," but instead of using windows, lenses, or mirrors to manipulate light and construct an image, mathematical formulas are used to describe the effects that particles and fields in the sample have on the light. These formulas have always contained terms that relate to the electron spin of magnetic atoms, but they were previously ignored. Using the full formula allows for the determination of not only crystal structure, but magnetic spin distribution and orientation as well, with a spatial resolution limited only by the wavelength of x-rays used. This promising method can be used at any coherent light source, including modern x-ray free-electron lasers, where ultrashort pulses would freeze-frame magnetic changes, offering the potential for imaging in unprecedented detail the structure and motion of boundaries between regions with different magnetic orientation.

371

Lensless Imaging of Magnetic Nanostructures  

NLE Websites -- All DOE Office Websites (Extended Search)

Lensless Imaging of Magnetic Nanostructures Print Lensless Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the ALS's soft x-rays have enabled scientists to apply lensless x-ray imaging for the first time to nanometer-scale magnetic structures in an alloy. Many Ways To See You open your eyes and detect the light rays streaming through your bedroom window (transmission), illuminating your socks on the floor (scattering). You put on your glasses (refraction) to detect the state of your image in the mirror (reflection). If you are an ALS scientist, perhaps you go to work and shine some x-ray light on a crystal to detect the arrangement of the atoms in the crystal (diffraction). Now, thanks to Turner et al., you can also shine some x-ray light on a magnetic sample to detect the arrangement of its electron spins through a method known as lensless imaging. This last example is an equally valid way to "see," but instead of using windows, lenses, or mirrors to manipulate light and construct an image, mathematical formulas are used to describe the effects that particles and fields in the sample have on the light. These formulas have always contained terms that relate to the electron spin of magnetic atoms, but they were previously ignored. Using the full formula allows for the determination of not only crystal structure, but magnetic spin distribution and orientation as well, with a spatial resolution limited only by the wavelength of x-rays used. This promising method can be used at any coherent light source, including modern x-ray free-electron lasers, where ultrashort pulses would freeze-frame magnetic changes, offering the potential for imaging in unprecedented detail the structure and motion of boundaries between regions with different magnetic orientation.

372

Lensless Imaging of Magnetic Nanostructures  

NLE Websites -- All DOE Office Websites (Extended Search)

Lensless Imaging of Magnetic Nanostructures Print Lensless Imaging of Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine. By studying the basics of magnetism, scientists aim to better understand the fundamental physical principles that govern magnetic systems, perhaps leading to important new technologies. The high brightness and coherence of the ALS's soft x-rays have enabled scientists to apply lensless x-ray imaging for the first time to nanometer-scale magnetic structures in an alloy. Many Ways To See You open your eyes and detect the light rays streaming through your bedroom window (transmission), illuminating your socks on the floor (scattering). You put on your glasses (refraction) to detect the state of your image in the mirror (reflection). If you are an ALS scientist, perhaps you go to work and shine some x-ray light on a crystal to detect the arrangement of the atoms in the crystal (diffraction). Now, thanks to Turner et al., you can also shine some x-ray light on a magnetic sample to detect the arrangement of its electron spins through a method known as lensless imaging. This last example is an equally valid way to "see," but instead of using windows, lenses, or mirrors to manipulate light and construct an image, mathematical formulas are used to describe the effects that particles and fields in the sample have on the light. These formulas have always contained terms that relate to the electron spin of magnetic atoms, but they were previously ignored. Using the full formula allows for the determination of not only crystal structure, but magnetic spin distribution and orientation as well, with a spatial resolution limited only by the wavelength of x-rays used. This promising method can be used at any coherent light source, including modern x-ray free-electron lasers, where ultrashort pulses would freeze-frame magnetic changes, offering the potential for imaging in unprecedented detail the structure and motion of boundaries between regions with different magnetic orientation.

373

Knot energy in unstretching ergodic magnetic flux tubes  

E-Print Network (OSTI)

Recently Titov et al [ApJ \\textbf{693},(2009) and ApJ (2007)] have made use of a covariant model to investigate magnetic reconnection of astrophysical plasmas. Earlier R Ricca [Phys Rev A (1991)] has used another covariant formalism, to investigated vortex filaments and solitons. This formalism, called Ricci rotation coefficients (RRC), is applied here, to the Chui and Moffatt [PRSA (1995)] knotted magnetic flux tube (MFT) Riemann metric in the case of vanishing stretch. It is shown that, the vanishing of some components of the (RRC) leads to unstretching knotted tubes. Computing of magnetic knot energy in terms of the RCC, shows that, uniform, unstretching and constant cross-section tubes leads to a marginal dynamo action over magnetic surfaces. Recent investigation on the role of stretching in plasma dynamo action showed that in diffusive media [Phys Plasma \\textbf{14} (2008)], unstretching unknotted tubes would not support fast dynamo action. This result was generalized here to much more general knotted MF...

de Andrade, Garcia

2009-01-01T23:59:59.000Z

374

Carbon Joins the Magnetic Club  

NLE Websites -- All DOE Office Websites (Extended Search)

Press Release 29 May 2007 Carbon Joins the Magnetic Club summary written by Brad Plummer, SLAC Communication Office The exclusive club of magnetic elements officially has a new member-carbon. Using a proton beam and advanced x-ray techniques, SLAC researchers in collaboration with colleagues from LBNL and the University of Leipzig in Germany have finally put to rest doubts about carbon's ability to be made magnetic. "In the past, some groups thought they had discovered magnetic carbon," said Hendrik Ohldag, the paper's lead author and SSRL staff scientist. "Unfortunately, they realized later that they were misled by small amounts of iron, cobalt or nickel in their samples." In Leipzig, Ohldag's team applied a beam of protons to disrupt and align a portion of the electrons in samples of pure carbon, magnetizing tiny, measurable spots within the carbon. The team then used the x-ray microscope at ALS to obtain images of the magnetized portions-a measurement only possible with a state-of-the-art microscope that uses the brilliant x-ray beams generated when electrons accelerate around the ring of a synchrotron. The x-ray beam also enabled the team to verify beyond doubt that the sample remained free of impurities during the experiments, unlike the case in previous studies.

375

Effect of self-magnetic fields on the nonlinear dynamics of relativistic electron beam with virtual cathode  

Science Conference Proceedings (OSTI)

The report is devoted to the results of the numerical study of the virtual cathode (VC) formation conditions in the relativistic electron beam (REB) under the influence of the self-magnetic and external axial magnetic fields. The azimuthal instability of the relativistic electron beam leading to the formation of the vortex electron structure in the system was found out. This instability is determined by the influence of the self-magnetic fields of the relativistic electron beam, and it leads to the decrease of the critical value of the electron beam current (current when the non-stationary virtual cathode is formed in the drift space). The typical dependencies of the critical current on the external uniform magnetic field value were discovered. The effect of the beam thickness on the virtual cathode formation conditions was also analyzed.

Hramov, A. E.; Koronovskii, A. A. [Saratov State University, Astrakhanskaja 83, Saratov 410012, Russia Saratov State Technical University, Politechnicheskaja 77, Saratov 410028 (Russian Federation); Kurkin, S. A. [Saratov State University, Astrakhanskaja 83, Saratov 410012 (Russian Federation); Filatova, A. E. [Saratov State Technical University, Politechnicheskaja 77, Saratov 410028 (Russian Federation)

2012-11-15T23:59:59.000Z

376

Superconducting magnet  

DOE Patents (OSTI)

A superconducting magnet designed to produce magnetic flux densities of the order of 4 to 5 Webers per square meter is constructed by first forming a cable of a plurality of matrixed superconductor wires with each wire of the plurality insulated from each other one. The cable is shaped into a rectangular cross-section and is wound with tape in an open spiral to create cooling channels. Coils are wound in a calculated pattern in saddle shapes to produce desired fields, such as dipoles, quadrupoles, and the like. Wedges are inserted between adjacent cables as needed to maintain substantially radial placement of the long dimensions of cross sections of the cables. After winding, individual strands in each of the cables are brought out to terminals and are interconnected to place all of the strands in series and to maximize the propagation of a quench by alternating conduction from an inner layer to an outer layer and from top half to bottom half as often as possible. Individual layers are separated from others by spiraled aluminum spacers to facilitate cooling. The wound coil is wrapped with an epoxy tape that is cured by heat and then machined to an interference fit with an outer aluminum pipe which is then affixed securely to the assembled coil by heating it to make a shrink fit. In an alternate embodiment, one wire of the cable is made of copper or the like to be heated externally to propagate a quench.

Satti, John A. (Naperville, IL)

1980-01-01T23:59:59.000Z

377

Thermomagnetic burn control for magnetic fusion reactor  

DOE Patents (OSTI)

Apparatus is provided for controlling the plasma energy production rate of a magnetic-confinement fusion reactor, by controlling the magnetic field ripple. The apparatus includes a group of shield sectors formed of ferromagnetic material which has a temperature-dependent saturation magnetization, with each shield lying between the plasma and a toroidal field coil. A mechanism for controlling the temperature of the magnetic shields, as by controlling the flow of cooling water therethrough, thereby controls the saturation magnetization of the shields and therefore the amount of ripple in the magnetic field that confines the plasma, to thereby control the amount of heat loss from the plasma. This heat loss in turn determines the plasma state and thus the rate of energy production.

Rawls, J.M.; Peuron, A.U.

1980-07-01T23:59:59.000Z

378

Thermomagnetic burn control for magnetic fusion reactor  

DOE Patents (OSTI)

Apparatus is provided for controlling the plasma energy production rate of a magnetic-confinement fusion reactor, by controlling the magnetic field ripple. The apparatus includes a group of shield sectors (30a, 30b, etc.) formed of ferromagnetic material which has a temperature-dependent saturation magnetization, with each shield lying between the plasma (12) and a toroidal field coil (18). A mechanism (60) for controlling the temperature of the magnetic shields, as by controlling the flow of cooling water therethrough, thereby controls the saturation magnetization of the shields and therefore the amount of ripple in the magnetic field that confines the plasma, to thereby control the amount of heat loss from the plasma. This heat loss in turn determines the plasma state and thus the rate of energy production.

Rawls, John M. (Del Mar, CA); Peuron, Unto A. (Solana Beach, CA)

1982-01-01T23:59:59.000Z

379

Magnet innovations for linacs  

Science Conference Proceedings (OSTI)

It is possible to produce large magnetic fields at the aperture of permanent magnet quadrupoles, even when the magnetic aperture is very small. That, combined with their compactness, makes permanent magnet quadrupoles very powerful components of small aperture linacs. Results will be presented about past and present work on both fixed and variable strength permanent magnets suitable for use in and around linacs.

Halbach, K.

1986-06-01T23:59:59.000Z

380

Origin State Destination State  

U.S. Energy Information Administration (EIA) Indexed Site

8. Estimated truck transportation rates for coal, state to state, EIA data 8. Estimated truck transportation rates for coal, state to state, EIA data Origin State Destination State 2008 2009 2010 2008-2010 2009-2010 Alabama Alabama W W W W W Alabama Georgia - - W - - Alabama Indiana W W - - - Colorado Colorado W W W W W Colorado Michigan - - W - - Illinois Florida W - - - - Illinois Illinois $7.51 $4.74 $3.37 -33.0 -28.8 Illinois Indiana W W - - - Illinois Minnesota W W - - - Illinois Missouri $21.73 $20.23 $13.30 -21.8 -34.3 Indiana Alabama - W - - -

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Origin State Destination State  

U.S. Energy Information Administration (EIA) Indexed Site

5. Estimated rail transportation rates for coal, state to state, STB data 5. Estimated rail transportation rates for coal, state to state, STB data Origin State Destination State 2001 2002 2003 2004 2005 2006 2007 2008 2009 2001-2009 2008-2009 Alabama Alabama W W W W W W W W W W W Alabama Georgia W W W W W W W W W W W Alabama Illinois - - - - - W W W W - W Colorado Alabama - W W W W W W W W - W Colorado Arizona W W W W W W W W W W W Colorado Arkansas - - - - W W W W - - -

382

Origin State Destination State  

U.S. Energy Information Administration (EIA) Indexed Site

4. Estimated rail transportation rates for coal, state to state, STB data 4. Estimated rail transportation rates for coal, state to state, STB data Origin State Destination State 2001 2002 2003 2004 2005 2006 2007 2008 2009 2001-2009 2008-2009 Alabama Alabama W W W W W W W W W W W Alabama Georgia W W W W W W W W W W W Alabama Illinois - - - - - W W W W - W Colorado Alabama - W W W W W W W W - W Colorado Arizona W W W W W W W W W W W Colorado Arkansas - - - - W W W W - - -

383

Origin State Destination State  

U.S. Energy Information Administration (EIA) Indexed Site

6. Estimated rail transportation rates for coal, state to state, STB data 6. Estimated rail transportation rates for coal, state to state, STB data Origin State Destination State 2001 2002 2003 2004 2005 2006 2007 2008 2009 2001-2009 2008-2009 Alabama Alabama W W W W W W W W W W W Alabama Georgia W W W W W W W W W W W Alabama Illinois - - - - - W W W W - W Colorado Alabama - W W W W W W W W - W Colorado Arizona W W W W W W W W W W W Colorado Arkansas - - - - W W W W - - -

384

Origin State Destination State  

U.S. Energy Information Administration (EIA) Indexed Site

5. Estimated barge transportation rates for coal, state to state, EIA data 5. Estimated barge transportation rates for coal, state to state, EIA data Origin State Destination State 2008 2009 2010 2008-2010 2009-2010 Alabama Alabama $4.31 $4.36 $5.01 7.9 15.0 Alabama Ohio W - - - - Colorado Alabama W - - - - Colorado Florida $11.08 $12.65 $13.27 9.4 4.9 Colorado Indiana $6.29 W - - - Colorado Iowa W - - - - Colorado Kentucky W - - - - Colorado Mississippi - - W - - Colorado Ohio - W - - - Colorado Tennessee W - - - - Illinois Alabama W $13.15 $14.28 W 8.6

385

Origin State Destination State  

U.S. Energy Information Administration (EIA) Indexed Site

6. Estimated barge transportation rates for coal, state to state, EIA data 6. Estimated barge transportation rates for coal, state to state, EIA data Origin State Destination State 2008 2009 2010 2008-2010 2009-2010 Alabama Alabama $3.97 $3.97 $4.52 6.7 13.7 Alabama Ohio W - - - - Colorado Alabama W - - - - Colorado Florida $10.21 $11.53 $11.95 8.2 3.7 Colorado Indiana $5.79 W - - - Colorado Iowa W - - - - Colorado Kentucky W - - - - Colorado Mississippi - - W - - Colorado Ohio - W - - - Colorado Tennessee W - - - - Illinois Alabama W $11.99 $12.87 W 7.3

386

Origin State Destination State  

U.S. Energy Information Administration (EIA) Indexed Site

7. Estimated truck transportation rates for coal, state to state, EIA data 7. Estimated truck transportation rates for coal, state to state, EIA data Origin State Destination State 2008 2009 2010 2008-2010 2009-2010 Alabama Alabama W W W W W Alabama Georgia - - W - - Alabama Indiana W W - - - Colorado Colorado W W W W W Colorado Michigan - - W - - Illinois Florida W - - - - Illinois Illinois $8.16 $5.20 $3.75 -32.2 -27.9 Illinois Indiana W W - - - Illinois Minnesota W W - - - Illinois Missouri $23.60 $22.20 $14.77 -20.9 -33.5 Indiana Alabama - W - - -

387

Magnetics and the body  

NLE Websites -- All DOE Office Websites (Extended Search)

no magnetic "charges"), such as from electromagnets. Magnetic fields are measured in Tesla (T) or Gauss (G). The Tesla is a very large unit (1 T 10,000 G). Most large magnets...

388

Learning About Magnets!  

NLE Websites -- All DOE Office Websites (Extended Search)

the National High Magnetic Field Laboratory Learning About Name A magnet is a material or object that creates a magnetic fi eld. This fi eld is invisible, but it creates a force...

389

ALS superbend magnet system  

E-Print Network (OSTI)

ALS Superbend Magnet System J. Zbasnik † , S. T. Wang †† ,of a High-Field Magnet for the ALS,” Transactions AppliedRefrigeration options for the ALS Superbend dipole magnets”,

2000-01-01T23:59:59.000Z

390

Characterization of waste tire incineration in a prototype vortexing fluidized bed combustor  

Science Conference Proceedings (OSTI)

To investigate the characteristics of incinerating waste tires in a prototype vortexing fluidized bed combustor, performance tests were conducted with two sizes of waste tire fragments. The results from the combustion experiments showed that increasing the tire particle size caused less of the volatiles to be burned in the freeboard and thus lowered freeboard temperature. Uniform bed temperature could also be achieved by increasing the size of the tire particles. Variations in the secondary and tertiary air rates simultaneously affected the swirling intensity and the axial gas velocity in the freeboard, and thus resulted in the variations in ash elutriation, combustion efficiency, and pollutant emissions for the combustion systems. 21 refs., 17 figs., 1 tab.

Teng, H.; Chyang, C.S.; Shang, S.H.; Ho, J.A. [Chung Yuan Christian Univ., Chung-Li (Taiwan, Province of China)

1997-01-01T23:59:59.000Z

391

Helical Magnets Project | Superconducting Magnet Division  

NLE Websites -- All DOE Office Websites (Extended Search)

RHIC, the basic construction unit is a superconducting dipole magnet producing a four tesla dipole field that rotates through 360 degrees in a length of 2.4 meters. The magnets...

392

Magnetization of neutron matter  

SciTech Connect

In this paper, we compute magnetization of neutron matter at strong magnetic field using the lowest order constrained variational (LOCV) technique.

Bigdeli, M. [Department of Physics, Zanjan University, P.O. Box 45195-313, Zanjan (Iran, Islamic Republic of)

2011-09-21T23:59:59.000Z

393

SUPERCONDUCTING MAGNETIC ENERGY STORAGE  

E-Print Network (OSTI)

Superconducting 30-MJ Energy Storage Coil", Proc. 19 80 ASC,Superconducting Magnetic Energy Storage Plant", IEEE Trans.SlIperconducting Magnetic Energy Storage Unit", in Advances

Hassenzahl, W.

2011-01-01T23:59:59.000Z

394

Magnetic Materials Group Homepage  

Science Conference Proceedings (OSTI)

... and simulation to become the driving force in ... develop a real-time magnetic domain imaging ... data-storage and permanent magnets with increased ...

2012-12-03T23:59:59.000Z

395

NSLS II: Magnetism  

NLE Websites -- All DOE Office Websites (Extended Search)

spatial ordering of the magnetic moments that is superimposed on the crystal lattice. Why these atomic magnetic moments survive and how they arrange in the solid is the...

396

Regenerator for Magnetic Refrigerants  

Ames Laboratory researchers have developed a new magnetic material that can be used at low temperatures (sub liquid hydrogen) for magnetic refrigerators.

397

Satellite Data Assimilation in Numerical Weather Prediction Models. Part II: Uses of Rain-Affected Radiances from Microwave Observations for Hurricane Vortex Analysis  

Science Conference Proceedings (OSTI)

A hybrid variational scheme (HVAR) is developed to produce the vortex analysis associated with tropical storms. This scheme allows for direct assimilation of rain-affected radiances from satellite microwave instruments. In the HVAR, the ...

Fuzhong Weng; Tong Zhu; Banghua Yan

2007-11-01T23:59:59.000Z

398

Vortex dynamics : a window into the properties of type-II superconductors  

E-Print Network (OSTI)

3. Electrical resistivity & Electric ?eld-current densityof magnetization, electrical resistivity, and speci?c heatdirection. II.B.3 Electrical resistivity & Electric ?eld-

Taylor, Benjamin Jeremy

2006-01-01T23:59:59.000Z

399

Origin State Destination State  

U.S. Energy Information Administration (EIA) Indexed Site

8. Estimated rail transportation rates for coal, state to state, EIA data 8. Estimated rail transportation rates for coal, state to state, EIA data Origin State Destination State 2008 2009 2010 2008-2010 2009-2010 Alabama Alabama $13.29 $12.39 $13.93 2.4 12.5 Alabama Georgia $17.62 $17.84 $20.09 6.8 12.6 Alabama Kentucky - W - - - Alabama New Jersey W - - - - Alabama Pennsylvania - W - - - Arizona Arizona W W W W W Colorado Alabama $31.79 $27.66 $24.93 -11.5 -9.9 Colorado Arizona $25.97 W - - - Colorado Arkansas W - - - - Colorado California - $34.20 $46.22 - 35.1 Colorado Colorado $13.04 $7.72 $8.13 -21.1 5.3

400

Origin State Destination State  

U.S. Energy Information Administration (EIA) Indexed Site

Estimated rail transportation rates for coal, state to state, EIA data Estimated rail transportation rates for coal, state to state, EIA data Origin State Destination State 2008 2009 2010 2008-2010 2009-2010 Alabama Alabama $14.43 $13.59 $15.46 3.5 13.8 Alabama Georgia $19.13 $19.58 $22.30 8.0 13.9 Alabama Kentucky - W - - - Alabama New Jersey W - - - - Alabama Pennsylvania - W - - - Arizona Arizona W W W W W Colorado Alabama $34.52 $30.35 $27.67 -10.5 -8.8 Colorado Arizona $28.20 W - - - Colorado Arkansas W - - - - Colorado California - $37.53 $51.30 - 36.7 Colorado Colorado $14.16 $8.47 $9.02 -20.2 6.6

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Progress in Steady-State Scenario Development in the DIII-D Tokamak (A26981)  

E-Print Network (OSTI)

Proc. Of 6th IAEA Technical Meeting On Steady-State Operation Of Magnetic Fusion Devices6th IAEA Technical Committee Meeting on Steady State Operation of Magnetic Fusion Devices Vienna, AT, 2010999617785

Luce, T.C.

2011-01-19T23:59:59.000Z

402

Local thermodynamics of a magnetized, anisotropic plasma  

SciTech Connect

An expression for the internal energy of a fluid element in a weakly coupled, magnetized, anisotropic plasma is derived from first principles. The result is a function of entropy, particle density and magnetic field, and as such plays the role of a thermodynamic potential: it determines in principle all thermodynamic properties of the fluid element. In particular it provides equations of state for the magnetized plasma. The derivation uses familiar fluid equations, a few elements of kinetic theory, the MHD version of Faraday's law, and certain familiar stability and regularity conditions.

Hazeltine, R. D.; Mahajan, S. M.; Morrison, P. J. [Department of Physics and Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712-1060 (United States)

2013-02-15T23:59:59.000Z

403

Magnetic frustration effects in uranium intermetallics  

SciTech Connect

The effect of geometrical frustration on the development of the heavy-fermion state and quantum criticality is studied in UAuCu{sub 4}, UAuPt{sub 4}, UAu{sub 3}Ni{sub 2} samples through measurements of their magnetic susceptibility, heat capacity, and electrical resistivity. In addition, since lattice disorder can play a large role in defining magnetic properties in frustrated systems, extended X-ray absorption fine structure (EXAFS) data have also been obtained. The local structure results show a strong correlation with the magnetic properties in these samples.

Jiang, Yu; Booth, C. H.; Tobash, P. H.; Gofryk, K.; Torrez, M. A.; Ronning, F.; Bauer, E. D.; Thompson, J. D.

2010-06-10T23:59:59.000Z

404

Meson Spectrum in Strong Magnetic Fields  

E-Print Network (OSTI)

We study the relativistic quark-antiquark system embedded in magnetic field. The Hamiltonian containing confinement, one gluon exchange and spin-spin interaction is derived. We analytically follow the evolution of the lowest meson states as a functions of MF strength. Calculating the one gluon exchange interaction energy and spin-spin contribution we have observed, that these corrections remain finite at large magnetic fields, preventing the vanishing of the total rho-meson mass at some B_crit, as previously thought. We display the rho masses as functions of magnetic field in comparison with recent lattice data.

M. A. Andreichikov; B. O. Kerbikov; V. D. Orlovsky; Yu. A. Simonov

2013-04-09T23:59:59.000Z

405

Vortex Diode Analysis and Testing for Fluoride Salt-Cooled High-Temperature Reactors  

SciTech Connect

Fluidic diodes are presently being considered for use in several fluoride salt-cooled high-temperature reactor designs. A fluidic diode is a passive device that acts as a leaky check valve. These devices are installed in emergency heat removal systems that are designed to passively remove reactor decay heat using natural circulation. The direct reactor auxiliary cooling system (DRACS) uses DRACS salt-to-salt heat exchangers (DHXs) that operate in a path parallel to the core flow. Because of this geometry, under normal operating conditions some flow bypasses the core and flows through the DHX. A flow diode, operating in reverse direction, is-used to minimize this flow when the primary coolant pumps are in operation, while allowing forward flow through the DHX under natural circulation conditions. The DRACSs reject the core decay heat to the environment under loss-of-flow accident conditions and as such are a reactor safety feature. Fluidic diodes have not previously been used in an operating reactor system, and therefore their characteristics must be quantified to ensure successful operation. This report parametrically examines multiple design parameters of a vortex-type fluidic diode to determine the size of diode needed to reject a particular amount of decay heat. Additional calculations were performed to size a scaled diode that could be tested in the Oak Ridge National Laboratory Liquid Salt Flow Loop. These parametric studies have shown that a 152.4 mm diode could be used as a test article in that facility. A design for this diode is developed, and changes to the loop that will be necessary to test the diode are discussed. Initial testing of a scaled flow diode has been carried out in a water loop. The 150 mm diode design discussed above was modified to improve performance, and the final design tested was a 171.45 mm diameter vortex diode. The results of this testing indicate that diodicities of about 20 can be obtained for diodes of this size. Experimental results show similar trends as the computational fluid dynamics (CFD) results presented in this report; however, some differences exist that will need to be assessed in future studies. The results of this testing will be used to improve the diode design to be tested in the liquid salt loop system.

Yoder Jr, Graydon L [ORNL; Elkassabgi, Yousri M. [Texas A& M University, Kingsville; De Leon, Gerardo I. [Texas A& M University, Kingsville; Fetterly, Caitlin N. [Texas A& M University, Kingsville; Ramos, Jorge A. [Texas A& M University, Kingsville; Cunningham, Richard Burns [University of Tennessee, Knoxville (UTK)

2012-02-01T23:59:59.000Z

406

Reduced gravity rankine cycle design and optimization with passive vortex phase separation  

E-Print Network (OSTI)

Liquid-metal Rankine power conversion systems (PCS) coupled with a fission reactor remain an attractive option for space power applications because system specific power and efficiency is very favorable for plant designs of 100 kW(e) or higher. Potential drawbacks to the technology in a reduced gravity environment include two-phase fluid management processes such as liquid-vapor phase separation. The most critical location for phase separation is at the boiler exit where only vapor must be sent to the turbine because blade erosion occurs from high velocity liquid droplets entrained by vapor flow. Previous studies have proposed that rotary separators be used to separate the liquid and vapor from a two phase mixture. However these devices have complex turbo machinery, require kilowatts of power and are untested for high vapor flow conditions. The Interphase Transport Phenomena (ITP) laboratory has developed a low-power, passive microgravity vortex phase separator (MVS) which has already proven to be an essential component of two-phase systems operating in low gravity environments. This thesis presents results from flight experiments where a Rankine cycle was operated in a reduced gravity environment for the first time by utilizing the MVS for liquid and vapor phase separation. The MVS was able to operate under saturated conditions and adjust to system transients as it would in the Rankine cycle by controlling the amount of liquid and vapor within the device. A new model is developed for the MVS to predict separation performance at high vapor flow conditions for sizing the separator at the boiler, condenser, and turbine locations within the cycle by using a volume limiting method. This model factors in the following separator characteristics: mass, pumping power, and available buffer volume for system transients. The study is concluded with overall Rankine efficiency and performance changes due to adding vortex phase separation and a schematic of the Rankine cycle with the integration of the MVS is presented. The results from this thesis indicate the thermal to electric efficiency and specific mass of the cycle can be improved by using the MVS to separate the two phases instead of a rotary separator.

Supak, Kevin Robert

2007-12-01T23:59:59.000Z

407

Reduced gravity Rankine cycle system design and optimization study with passive vortex phase separation  

E-Print Network (OSTI)

Liquid-metal Rankine power conversion systems (PCS) coupled with a fission reactor remain an attractive option for space power applications because system specific power and efficiency is very favorable for plant designs of 100 kW(e) or higher. Potential drawbacks to the technology in a reduced gravity environment include two-phase fluid management processes such as liquid-vapor phase separation. The most critical location for phase separation is at the boiler exit where only vapor must be sent to the turbine because blade erosion occurs from high velocity liquid droplets entrained by vapor flow. Previous studies have proposed that rotary separators be used to separate the liquid and vapor from a two phase mixture. However these devices have complex turbo machinery, require kilowatts of power and are untested for high vapor flow conditions. The Interphase Transport Phenomena (ITP) laboratory has developed a low-power, passive microgravity vortex phase separator (MVS) which has already proven to be an essential component of two-phase systems operating in low gravity environments. This thesis presents results from flight experiments where a Rankine cycle was operated in a reduced gravity environment for the first time by utilizing the MVS for liquid and vapor phase separation. The MVS was able to operate under saturated conditions and adjust to system transients as it would in the Rankine cycle by controlling the amount of liquid and vapor within the device. A new model is developed for the MVS to predict separation performance at high vapor flow conditions for sizing the separator at the boiler, condenser, and turbine locations within the cycle by using a volume limiting method. This model factors in the following separator characteristics: mass, pumping power, and available buffer volume for system transients. The study is concluded with overall Rankine efficiency and performance changes due to adding vortex phase separation and a schematic of the Rankine cycle with the integration of the MVS is presented. The results from this thesis indicate the thermal to electric efficiency and specific mass of the cycle can be improved by using the MVS to separate the two phases instead of a rotary separator.

Supak, Kevin Robert

2007-12-01T23:59:59.000Z

408

Nanocomposite Magnets: Transformational Nanostructured Permanent Magnets  

SciTech Connect

Broad Funding Opportunity Announcement Project: GE is using nanomaterials technology to develop advanced magnets that contain fewer rare earth materials than their predecessors. Nanomaterials technology involves manipulating matter at the atomic or molecular scale, which can represent a stumbling block for magnets because it is difficult to create a finely grained magnet at that scale. GE is developing bulk magnets with finely tuned structures using iron-based mixtures that contain 80% less rare earth materials than traditional magnets, which will reduce their overall cost. These magnets will enable further commercialization of HEVs, EVs, and wind turbine generators while enhancing U.S. competitiveness in industries that heavily utilize these alternatives to rare earth minerals.

None

2010-10-01T23:59:59.000Z

409

HTS Magnet Program | Superconducting Magnet Division  

NLE Websites -- All DOE Office Websites (Extended Search)

HTS Magnet Program HTS Magnet Program High Temperature Superconductors (HTS) have the potential to revolutionize the field of superconducting magnets for particle accelerators, energy storage and medical applications. This is because of the fact that as compared to the conventional Low Temperature Superconductors (LTS), the critical current density (Jc ) of HTS falls slowly both: as a function of increasing field, and as a function of increasing temperature These unique properties can be utilized to design and build: HTS magnets that produce very high fields (20 - 50 T) HTS magnets that operate at elevated temperatures (20 - 77 K) This is a significant step forward over the convention LTS magnets which generally operate at a temperature of ~4 K and with field usually limited

410

Proposed Detection of Dynamically Oriented Nuclei by Acoustic Nuclear Magnetic Resonance  

Science Conference Proceedings (OSTI)

It is proposed that acoustic nuclear magnetic resonance be used to detect steady?state nuclear orientation achieved by the Jeffries Abragam effect. This is a new scheme for double magnetic resonance (ADMR) in contrast with conventional DMR

Mary Duns Scotus Breitbart; W. A. Barker

1967-01-01T23:59:59.000Z

411

Tamper resistant magnetic stripes  

DOE Patents (OSTI)

This invention relates to a magnetic stripe comprising a medium in which magnetized particles are suspended and in which the encoded information is recorded by actual physical rotation or alignment of the previously magnetized particles within the flux reversals of the stripe which are 180.degree. opposed in their magnetic polarity. The magnetized particles are suspended in a medium which is solid, or physically rigid, at ambient temperatures but which at moderately elevated temperatures, such as 40.degree. C., is thinable to a viscosity permissive of rotation of the particles therein under applications of moderate external magnetic field strengths within acceptable time limits.

Naylor, Richard Brian (Albuquerque, NM); Sharp, Donald J. (Albuquerque, NM)

1999-01-01T23:59:59.000Z

412

Winding numbers and scaling tilts from random vortex-antivortex pairs  

E-Print Network (OSTI)

I show that random distributions of vortex-antivortex pairs (rather than of individual vortices) lead to scaling of typical winding numbers W trapped inside a loop of circumference C with the square root of C when the expected winding numbers are large. Such scaling is consistent with the Kibble-Zurek mechanism (KZM). By contrast, distribution of individual vortices with randomly assigned topological charges would result in the dispersion of W scaling with the square root of the area inside C. Scaling of the dispersion of W and of the probability of detection of non-zero W with C can be also studied for loops so small that non-zero windings are rare. In this case I show a doubling of the scaling of dispersion with C when compared to the scaling of dispersion in the large W regime. Moreover, probability of trapping of a non-zero W becomes, in this case, proportional to the area subtended by C (hence, to the square of circumference). This quadruples, as compared with large winding numbers regime, the exponent in the power law dependence of the frequency of trapping of W=+1 or W=-1 on C. Such change of the power law exponent by a FACTOR OF FOUR implies quadrupling of the scaling of the frequency of winding number trapping with the quench rate, and is of key importance for experimental tests of KZM.

Wojciech H. Zurek

2013-05-21T23:59:59.000Z

413

Lensless Imaging of Magnetic Nanostructures  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnetic Nanostructures Print Magnetism is useful for many devices and techniques, from electric motors and computer hard drives to magnetic resonance imaging used in medicine....

414

State Agencies  

NLE Websites -- All DOE Office Websites (Extended Search)

Agencies Beatrice State Developmental Center, Nebraska Black Hills State University, SD, South Dakota Fergus Falls State Hospital, Minnesota Hastings Regional Center, Nebraska...

415

LHC Magnet Program | Superconducting Magnet Division  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnet Program Magnet Program The Superconducting Magnet Division is building a number of dipole magnets for the Large Hadron Collider (LHC), which is now under construction at CERN in Geneva, Switzerland. Scheduled to begin operation in 2007, this machine will collide beams of protons with the unprecedented energy of 7 TeV per beam to explore the nature of matter at its most basic level (RHIC can collide beams of protons with energies of 0.25 TeV, but is mostly used to collide heavy ions with energies of 0.1 TeV per nucleon). The magnets are being built as part of the US program, recommended by the High Energy Physics Advisory Panel (HEPAP) and approved by Congress, to contribute to the construction and, later, use of that frontier machine by the US high energy physics community. Fermi National Accelerator Laboratory (FNAL) and

416

Active magnetic regenerator  

SciTech Connect

The disclosure is directed to an active magnetic regenerator apparatus and method. Brayton, Stirling, Ericsson, and Carnot cycles and the like may be utilized in an active magnetic regenerator to provide efficient refrigeration over relatively large temperature ranges.

Barclay, John A. (Los Alamos, NM); Steyert, William A. (Los Alamos, NM)

1982-01-01T23:59:59.000Z

417

ALS superbend magnet performance  

E-Print Network (OSTI)

ALS Superbend Magnet Performance S. Marks, J. Zbasnik, W.the Advanced Light Source (ALS), with the fourth magnet as ahe Advanced Light Source (ALS) at the Lawrence Berkeley

2001-01-01T23:59:59.000Z

418

Scanning Hall Probe Microscopy of Magnetic Vortices inVery Underdoped yttrium-barium-copper-oxide  

Science Conference Proceedings (OSTI)

Since their discovery by Bednorz and Mueller (1986), high-temperature cuprate superconductors have been the subject of intense experimental research and theoretical work. Despite this large-scale effort, agreement on the mechanism of high-T{sub c} has not been reached. Many theories make their strongest predictions for underdoped superconductors with very low superfluid density n{sub s}/m*. For this dissertation I implemented a scanning Hall probe microscope and used it to study magnetic vortices in newly available single crystals of very underdoped YBa{sub 2}Cu{sub 3}O{sub 6+x} (Liang et al. 1998, 2002). These studies have disproved a promising theory of spin-charge separation, measured the apparent vortex size (an upper bound on the penetration depth {lambda}{sub ab}), and revealed an intriguing phenomenon of ''split'' vortices. Scanning Hall probe microscopy is a non-invasive and direct method for magnetic field imaging. It is one of the few techniques capable of submicron spatial resolution coupled with sub-{Phi}{sub 0} (flux quantum) sensitivity, and it operates over a wide temperature range. Chapter 2 introduces the variable temperature scanning microscope and discusses the scanning Hall probe set-up and scanner characterizations. Chapter 3 details my fabrication of submicron GaAs/AlGaAs Hall probes and discusses noise studies for a range of probe sizes, which suggest that sub-100 nm probes could be made without compromising flux sensitivity. The subsequent chapters detail scanning Hall probe (and SQUID) microscopy studies of very underdoped YBa{sub 2}Cu{sub 3}O{sub 6+x} crystals with T{sub c} {le} 15 K. Chapter 4 describes two experimental tests for visons, essential excitations of a spin-charge separation theory proposed by Senthil and Fisher (2000, 2001b). We searched for predicted hc/e vortices (Wynn et al. 2001) and a vortex memory effect (Bonn et al. 2001) with null results, placing upper bounds on the vison energy inconsistent with the theory. Chapter 5 discusses imaging of isolated vortices as a function of T{sub c}. Vortex images were fit with theoretical magnetic field profiles in order to extract the apparent vortex size. The data for the lowest T{sub c}'s (5 and 6.5 K) show some inhomogeneity and suggest that {lambda}{sub ab} might be larger than predicted by the T{sub c} {proportional_to} n{sub s}(0)/m* relation first suggested by results of Uemura et al. (1989) for underdoped cuprates. Finally, Chapter 6 examines observations of apparent ''partial vortices'' in the crystals. My studies of these features indicate that they are likely split pancake vortex stacks. Qualitatively, these split stacks reveal information about pinning and anisotropy in the samples. Collectively these magnetic imaging studies deepen our knowledge of cuprate superconductivity, especially in the important regime of low superfluid density.

Guikema, Janice Wynn; /SLAC, SSRL

2005-12-02T23:59:59.000Z

419

Superconducting magnet of Aurora  

Science Conference Proceedings (OSTI)

The AURORAsuperconducting magnet system is composed of a cylindrical single?body magnet and a refrigeration system for superconducting coils. The magnet generates B z =1 T on the central orbit at the 150 MeV electron beam injection energy and B z =4.3 T at the 650 MeV storage energy. The diameter of the central orbit is 1 m. Iron poles and yokes are used for shielding the magnetic field

T. Takayama; SHI Accelerator Research Group

1989-01-01T23:59:59.000Z

420

Magnetic Materials Staff  

Science Conference Proceedings (OSTI)

... Materials Science and Engineering Division Staff Directory; MML Organization. Contact. Magnetic Materials Group Robert Shull, Group Leader. ...

2012-10-09T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Magnetic Nanoparticle Metrology  

Science Conference Proceedings (OSTI)

... T2 relaxation times, hysteretic energy loss, etc ... Optimization of magnetic nanoparticle synthesis for ... competition between lattice energies and dipolar ...

2012-12-03T23:59:59.000Z

422

Irreversible magnetic switch  

DOE Patents (OSTI)

This invention is comprised of an irreversible magnetic switch containing a ferromagnetic amorphous metal having a predetermined crystallization temperature in its inductor magnetic path. With the incorporation of such material, the magnetic properties after cooling from a high temperature excursion above its crystallization temperature are only a fraction of the original value. The difference is used to provide a safety feature in the magnetic switch.

Karnowsky, M.M.; Yost, F.G.

1991-12-31T23:59:59.000Z

423

Baldrige Impacts, State by State  

Science Conference Proceedings (OSTI)

... Several states are providing coverage for other states without current programs. To learn more about impacts and benefits in each state select a ...

424

Magnetic nanohole superlattices  

DOE Patents (OSTI)

A magnetic material is disclosed including a two-dimensional array of carbon atoms and a two-dimensional array of nanoholes patterned in the two-dimensional array of carbon atoms. The magnetic material has long-range magnetic ordering at a temperature below a critical temperature Tc.

Liu, Feng

2013-05-14T23:59:59.000Z

425

Tunable Magnetic Regenerator/Refrigerant  

Magnetic regenerators utilize the magnetocaloric effect--the ability of a magnetic field to reduce the magnetic part of a solid materials entropy, generating heat, and then removing the magnetic field, permitting the reduction of temperature with the ...

426

Whirlpools on the Nanoscale Could Multiply Magnetic Memory  

NLE Websites -- All DOE Office Websites (Extended Search)

Whirlpools on the Nanoscale Could Whirlpools on the Nanoscale Could Multiply Magnetic Memory Whirlpools on the Nanoscale Could Multiply Magnetic Memory Print Tuesday, 21 May 2013 00:00 Research at the Advanced Light Source may lead to four-bit magnetic cells housed on nanoscale metal disks, instead of the two-bit magnetic domains of standard magnetic memories. In magnetic vortices, parallel electron spins point either clockwise or counterclockwise, while in their crowded centers the spins point either down or up. "From the scientist's point of view, magnetism is about controlling electron spin," says Peter Fischer of the Materials Sciences Division, who leads the work at beamline 6.1.2. Four orientations could provide multibits in a new kind of memory. The next step is to control the states independently and simultaneously.

427

Streamline magnetic inspection of OCTGs  

Science Conference Proceedings (OSTI)

This article reports that supply and demand imbalances in the drilling industry are allowing operators to make drilling contracts more stringent, despite reduced day rates. One typical requirement is more thorough inspection of drill string and bottomhole assemblies to ensure equipment-related failures don't increase costs. Magnetic inspection techniques for oil country tubular goods are becoming more advanced. However, common misperceptions often needlessly plague the inspection process. Today, almost all high-grade tubular goods are inspected in the plain-end state according to guidelines which are more stringent than those outlined by API inspection specification 5AX. Most tubular goods are inspected three to four times before the operator is satisfied they are suitable to run downhole. Often such inspections are conducted by different companies employing at least two techniques: magnetic flux leakage (MFL) and ultrasonics (US).

Stanley, R.

1987-01-01T23:59:59.000Z

428

Separation of magnetic field lines  

SciTech Connect

The field lines of magnetic fields that depend on three spatial coordinates are shown to have a fundamentally different behavior from those that depend on two coordinates. Unlike two-coordinate cases, a flux tube in a magnetic field that depends on all three spatial coordinates that has a circular cross section at one location along the tube characteristically has a highly distorted cross section at other locations. In an ideal evolution of a magnetic field, the current densities typically increase. Crudely stated, if the current densities increase by a factor {sigma}, the ratio of the long to the short distance across a cross section of a flux tube characteristically increases by e{sup 2{sigma}}, and the ratio of the longer distance to the initial radius increases as e{sup {sigma}}. Electron inertia prevents a plasma from isolating two magnetic field structures on a distance scale shorter than c/{omega}{sub pe}, which is about 10 cm in the solar corona, and reconnection must be triggered if {sigma} becomes sufficiently large. The radius of the sun, R{sub Circled-Dot-Operator }=7 Multiplication-Sign 10{sup 10}cm is about e{sup 23} times larger, so when {sigma} Greater-Than-Or-Equivalent-To 23, two lines separated by c/{omega}{sub pe} at one location can be separated by the full scale of any magnetic structures in the corona at another. The conditions for achieving a large exponentiation, {sigma}, are derived, and the importance of exponentiation is discussed.

Boozer, Allen H. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)

2012-11-15T23:59:59.000Z

429

Magnetic damping for maglev  

DOE Green Energy (OSTI)

Magnetic damping is one of the important parameters to control the response and stability of maglev systems. An experimental study is presented to measure the magnetic damping using a direct method. A plate attached to a permanent magnet levitated on a rotating drum was tested to investigate the effect of various parameters on magnetic damping such as conductivity, gap, excitation frequency, and oscillation amplitude. The experimental technique is capable of measuring all magnetic damping coefficients, some of which can not be measured by an indirect method.

Chen, S.S.; Zhu, S.; Cai, Y.; Rote, D.M. [Argonne National Lab., IL (United States). Energy Technology Div.

1994-12-31T23:59:59.000Z

430

Magnetically attached sputter targets  

DOE Patents (OSTI)

An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material is described. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly. 11 figures.

Makowiecki, D.M.; McKernan, M.A.

1994-02-15T23:59:59.000Z

431

Heat Transfer Enhancement for Finned-Tube Heat Exchangers with Vortex Generators: Experimental and Numerical Results  

Science Conference Proceedings (OSTI)

A combined experimental and numerical investigation is under way to investigate heat transfer enhancement techniques that may be applicable to large-scale air-cooled condensers such as those used in geothermal power applications. The research is focused on whether air-side heat transfer can be improved through the use of finsurface vortex generators (winglets,) while maintaining low heat exchanger pressure drop. A transient heat transfer visualization and measurement technique has been employed in order to obtain detailed distributions of local heat transfer coefficients on model fin surfaces. Pressure drop measurements have also been acquired in a separate multiple-tube row apparatus. In addition, numerical modeling techniques have been developed to allow prediction of local and average heat transfer for these low-Reynolds-number flows with and without winglets. Representative experimental and numerical results presented in this paper reveal quantitative details of local fin-surface heat transfer in the vicinity of a circular tube with a single delta winglet pair downstream of the cylinder. The winglets were triangular (delta) with a 1:2 height/length aspect ratio and a height equal to 90% of the channel height. Overall mean fin-surface Nusselt-number results indicate a significant level of heat transfer enhancement (average enhancement ratio 35%) associated with the deployment of the winglets with oval tubes. Pressure drop measurements have also been obtained for a variety of tube and winglet configurations using a single-channel flow apparatus that includes four tube rows in a staggered array. Comparisons of heat transfer and pressure drop results for the elliptical tube versus a circular tube with and without winglets are provided. Heat transfer and pressure-drop results have been obtained for flow Reynolds numbers based on channel height and mean flow velocity ranging from 700 to 6500.

O'Brien, James Edward; Sohal, Manohar Singh; Huff, George Albert

2002-08-01T23:59:59.000Z

432

Investigation of vortex generators for augmentation of wind turbine power performance  

SciTech Connect

This study focuses on the use of vortex generators (VGs) for performance augmentation of the stall-regulated AWT-26 wind turbine. The goal was to design a VG array which would increase annual energy production (AEP) by increasing power output at moderate wind speeds, without adversely affecting the loads or stall-regulation performance of the turbine. Wind tunnel experiments were conducted at the University of Washington to evaluate the effect of VGs on the AWT-26 blade, which is lofted from National Renewable Energy Laboratory (NREL) S-series airfoils. Based on wind-tunnel results and analysis, a VG array was designed and then tested on the AWT-26 prototype, designated P1. Performance and loads data were measured for P1, both with and without VGs installed. the turbine performance with VGs met most of the design requirements; power output was increased at moderate wind speeds with a negligible effect on peak power. However, VG drag penalties caused a loss in power output for low wind speeds, such that performance with VGs resulted in a net decrease in AEP for sites having annual average wind speeds up to 8.5 m/s. While the present work did not lead to improved AEP for the AWT-2 turbine, it does provide insight into performance augmentation of wind turbines with VGs. The safe design of a VG array for a stall-regulated turbine has been demonstrated, and several issues involving optimal performance with VGs have been identified and addressed. 15 refs., 34 figs., 10 tabs.

Griffin, D.A. [Lynette (R.) and Associates, Seattle, WA (United States)

1996-12-01T23:59:59.000Z

433

Steady state compact toroidal plasma production  

DOE Patents (OSTI)

Apparatus and method for maintaining steady state compact toroidal plasmas. A compact toroidal plasma is formed by a magnetized coaxial plasma gun and held in close proximity to the gun electrodes by applied magnetic fields or magnetic fields produced by image currents in conducting walls. Voltage supply means maintains a constant potential across the electrodes producing an increasing magnetic helicity which drives the plasma away from a minimum energy state. The plasma globally relaxes to a new minimum energy state, conserving helicity according to Taylor's relaxation hypothesis, and injecting net helicity into the core of the compact toroidal plasma. Controlling the voltage so as to inject net helicity at a predetermined rate based on dissipative processes maintains or increases the compact toroidal plasma in a time averaged steady state mode.

Turner, William C. (Livermore, CA)

1986-01-01T23:59:59.000Z

434

Vortex induced vibration for aquatic clean power (VIVACE)NOTE FROM ACM: It has been determined that the author of this article plagiarized the contents from a previously published paper. Therefore ACM has shut off access to this paper.  

Science Conference Proceedings (OSTI)

NOTE FROM ACM: It has been determined that the author of this article plagiarized the contents from a previously published paper. Therefore ACM has shut off access to this paper. The paper by M. K. Raj and B. G. Muthuraj plagiarizes the ... Keywords: VIVACE, reynolds number, undulations, vortex shedding, vortex vibrations

M. K. Raj; B. G. Muthuraj

2011-02-01T23:59:59.000Z

435

Theory of magnetization transport in a spatially varying magnetic field derived from entropic considerations  

E-Print Network (OSTI)

A theory of magnetization transport of a single spin-species in a spatially varying magnetic field is derived from entropic considerations. The theory describes thermodynamic transport in the language of differential geometry. Both magnetization diffusion and separation are predicted from a sample geometry, a magnetic field geometry, an entropy density function, and a single space-time scale. It is expressed first and most generally as coupled nonlinear partial differential equations, which are valid for the regime of high dipole-energy and magnetization. Second, the nonlinear model is explored in the limit of low dipole-energy (semi-linear), from which is derived a physical parameter characterizing separative magnetization transport (SMT). It is shown that the necessary and sufficient condition for SMT to occur is that the SMT parameter is spatially inhomogeneous. Third, the high spin-temperature (linear) limit is derived, and is shown to be equivalent to the model of nuclear spin transport of Genack and Redfield. Differences among the three models are illustrated by numerical solution. A family of analytic, steady-state solutions to the nonlinear transport equation is derived and shown to be the spin-temperature analog of the Langevin paramagnetic equation and Curie's law. A steady-state solution for the magnetization is shown to be equivalent to the widely applied separation equation of Fenske. Moreover, we show that the SMT parameter is functionally related to the relative volatility parameter of Fenske.

Rico A. R. Picone; Joseph L. Garbini; John A. Sidles

2013-10-28T23:59:59.000Z

436

Propagation of an arbitrary vortex pair through an astigmatic optical system and determination of its net topological charge  

E-Print Network (OSTI)

We embed a pair of vortices with different topological charges in a Gaussian beam and study its evolution through an astigmatic optical system, a tilted lens. The propagation dynamics is explained by a closed-form analytical expression. Furthermore, we show that a careful examination of the intensity distribution at a predicted position past the lens can provide us with the net charge present in the beam. To the best of our knowledge, our method is the first non-interferometric technique to measure the net charge of an arbitrary vortex pair. Our experimental results are in close agreement with the theoretical predictions.

Reddy, Salla Gangi; Aadhi, A; Banerji, J; Singh, R P

2013-01-01T23:59:59.000Z

437

Magnetic field switching in parallel quantum dots  

E-Print Network (OSTI)

We show that the Coulomb blockade in parallel dots pierced by magnetic flux $\\Phi$ completely blocks the resonant current for any value of $\\Phi$ except for integer multiples of the flux quantum $\\Phi_0$. This non-analytic (switching) dependence of the current on $\\Phi$ arises only when the dot states that carry the current are of the same energy. The time needed to reach the steady state, however, diverges when $\\Phi\\to n\\Phi_0$.

Feng Li; Xin-Qi Li; Wei-Min Zhang; S. A. Gurvitz

2008-03-11T23:59:59.000Z

438

FIRST 100 T NON-DESTRUCTIVE MAGNET  

DOE Green Energy (OSTI)

The first 100 T non-destructive (100 T ND) magnet and power supplies as currently designed are described. This magnet will be installed as part of the user facility research equipment at the National High Magnetic Field Laboratory (NHMFL) Pulsed Field Facility at Los Alamos National Laboratory. The 100 T ND magnet will provide a 100 T pulsed field of 5 ms duration (above 90% of full field) in a 15 mm diameter bore once per hour. Magnet operation will be non-destructive. The magnet will consist of a controlled power outer coil set which produces a 47 T platform field in a 225 mm diameter bore. Located within the outer coil set will be a 220 mm outer diameter capacitor powered insert coil. Using inertial energy storage a synchronous motor/generator will provide ac power to a set of seven ac-dc converters rated at 64 MW/80 MVA each. These converters will energize three independent coil circuits to create 170 MJ of field energy in the outer coil set at the platform field of 47 T. The insert will then be energized to produce the balance of the 100 T peak field using a 2.3 MJ, 18 kV (charged to 15 kV), 14.4 mF capacitor bank controlled with solid-state switches. The magnet will be the first of its kind and the first non-destructive, reusable 100 T pulsed magnet. The operation of the magnet will be described along with special features of its design and construction.

J. R. SIMS; ET AL

1999-10-01T23:59:59.000Z

439

Quark-gluon plasma in an external magnetic field  

E-Print Network (OSTI)

Using numerical simulations of lattice QCD we calculate the effect of an external magnetic field on the equation of state of the quark-gluon plasma. The results are obtained using a Taylor expansion of the pressure with respect to the magnetic field for the first time. The coefficients of the expansion are computed to second order in the magnetic field. Our setup for the external magnetic field avoids complications arising from toroidal boundary conditions, making a Taylor series expansion straightforward. This study is exploratory and is meant to serve as a proof of principle.

L. Levkova; C. DeTar

2013-09-04T23:59:59.000Z

440

High Field Magnet R&D |Superconducting Magnet Division  

NLE Websites -- All DOE Office Websites (Extended Search)

High Field Magnet R&D High Field Magnet R&D The Superconducting Magnet Division is developing advanced magnet designs and magnet-related technologies for high field accelerator magnets. We are currently working on magnets for three inter-related programs: High Field Magnets for Muon Collider Papers, Presentations Common Coil Magnets Papers, Presentations Interaction Region Magnets Papers, Presentations High Temperature Superconductor (HTS) Magnets Papers, Presentations This is part of a multi-lab superconducting magnet development program for new accelerator facilities that would be part of the U.S. High Energy Physics program. These programs (@BNL, @FNAL, @LBNL) are quite complimentary to each other, so that magnet designs and technologies developed at one laboratory can be easily transferred to another. The BNL

Note: This page contains sample records for the topic "magnetic vortex state" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Model Predictive Control of a Permanent Magnet Synchronous Motor with Experimental Validation  

E-Print Network (OSTI)

Model Predictive Control of a Permanent Magnet Synchronous Motor with Experimental Validation Shan to regulate the speed of a permanent magnet synchronous motor where the design is based on a linearized state rejection, constraints, quadratic programming. 1. Introduction Permanent Magnet Synchronous Motors (PMSMs

442

Cool Magnetic Molecules  

NLE Websites -- All DOE Office Websites (Extended Search)

Cool Magnetic Molecules Cool Magnetic Molecules Cool Magnetic Molecules Print Wednesday, 25 May 2011 00:00 Certain materials are known to heat up or cool down when they are exposed to a changing magnetic field. This is known as the magnetocaloric effect. All magnetic materials exhibit this effect, but in most cases, it is too small to be technologically useful. Recently, however, the search for special molecules with a surprisingly large capacity to keep cool has heated up, driven by environmental and cost considerations as well as by recent improvements in our ability to design, assemble, and probe the structure and chemistry of small molecules. An international collaboration of researchers from Spain, Scotland, and the U.S. has utilized ALS Beamline 11.3.1 (small-molecule crystallography) to characterize the design of such "molecular coolers." The work targets the synthesis of molecular cluster compounds containing many unpaired electrons ("nanomagnets") for applications involving enhanced magnetic refrigeration at very low temperatures.

443

Flame-vortex interaction and mixing behaviors of turbulent non-premixed jet flames under acoustic forcing  

SciTech Connect

This study examines the effect of acoustic excitation using forced coaxial air on the flame characteristics of turbulent hydrogen non-premixed flames. A resonance frequency was selected to acoustically excite the coaxial air jet due to its ability to effectively amplify the acoustic amplitude and reduce flame length and NO{sub x} emissions. Acoustic excitation causes the flame length to decrease by 15% and consequently, a 25% reduction in EINO{sub x} is achieved, compared to coaxial air flames without acoustic excitation at the same coaxial air to fuel velocity ratio. Moreover, acoustic excitation induces periodical fluctuation of the coaxial air velocity, thus resulting in slight fluctuation of the fuel velocity. From phase-lock PIV and OH PLIF measurement, the local flow properties at the flame surface were investigated under acoustic forcing. During flame-vortex interaction in the near field region, the entrainment velocity and the flame surface area increased locally near the vortex. This increase in flame surface area and entrainment velocity is believed to be a crucial factor in reducing flame length and NO{sub x} emission in coaxial jet flames with acoustic excitation. Local flame extinction occurred frequently when subjected to an excessive strain rate, indicating that intense mass transfer of fuel and air occurs radially inward at the flame surface. (author)

Kim, Munki; Choi, Youngil; Oh, Jeongseog; Yoon, Youngbin [School of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea)

2009-12-15T23:59:59.000Z

444

Pulse magnetic welder  

DOE Patents (OSTI)

A welder is described for automated closure of fuel pins by a pulsed magnetic process in which the open end of a length of cladding is positioned within a complementary tube surrounded by a pulsed magnetic welder. Seals are provided at each end of the tube, which can be evacuated or can receive tag gas for direct introduction to the cladding interior. Loading of magnetic rings and end caps is accomplished automatically in conjunction with the welding steps carried out within the tube.

Christiansen, D.W.; Brown, W.F.

1984-01-01T23:59:59.000Z

445

Magnetic latching solenoid  

DOE Patents (OSTI)

This invention discloses a D.C. magnetic latching solenoid that retains a moving armature in a first or second position by means of a pair of magnets, thereby having a zero-power requirement after actuation. The first or second position is selected by reversing the polarity of the D.C. voltage which is enough to overcome the holding power of either magnet and transfer the armature to an opposite position. The coil is then de-energized.

Marts, Donna J. (Idaho Falls, ID); Richardson, John G. (Idaho Falls, ID); Albano, Richard K. (Idaho Falls, ID); Morrison, Jr., John L. (Idaho Falls, ID)

1995-01-01T23:59:59.000Z

446

VOLUME 77, NUMBER 22 P H Y S I C A L R E V I E W L E T T E R S 25 NOVEMBER 1996 Effect of Magnetic Scattering on the 3He Superfluid State in Aerogel  

E-Print Network (OSTI)

Scattering on the 3He Superfluid State in Aerogel D. T. Sprague, T. M. Haard, J. B. Kycia, M. R. Rand, Y. Lee, Evanston, Illinois 60208 (Received 6 August 1996) Pure 3 He in highly porous aerogel forms an equal and nonmagnetic quasiparticle scattering from solid 3 He at the aerogel surface is important to the superfluid

Le Roy, Robert J.

447

Nanostructrured Magnetic Materials  

Science Conference Proceedings (OSTI)

Aug 8, 2013 ... The demand for OFF-ON becomes increasingly important as ... The residual magnetic flux density and maximum energy product of the ...

448

Rare Earth Magnets  

Science Conference Proceedings (OSTI)

Mar 6, 2013 ... Performance and Endurance of Nd-Fe-B Sintered Magnets in E-Motor Application Conditions: Martina Moore1; Ralph Sueptitz1; Margitta ...

449

Rare Earth Magnets  

Science Conference Proceedings (OSTI)

Aug 8, 2013 ... Current high performance permanent magnets (PM) for traction motors of (hybrid) electric vehicles use substantial amount of Dy in Nd-Fe-B ...

450

Magnetic Materials and Properties  

Science Conference Proceedings (OSTI)

Aug 5, 2013 ... Following vacuum distillation of the Mg-RE alloy, 98% pure RE metals can be recovered, which are then used to synthesize permanent magnet ...

451

Quantum Computation with Magnetic Clusters  

E-Print Network (OSTI)

We propose a complete, quantitative quantum computing system which satisfies the five DiVincenzo criteria. The model is based on magnetic clusters with uniaxial anisotropy, where standard, two-state qubits are formed utilizing the two lowest-lying states of an anisotropic potential energy. We outline the quantum dynamics required by quantum computing for single qubit structures, and then define a novel measurement scheme in which qubit sates can be measured by sharp changes in current as voltage across the cluster is varied. We then extend the single qubit description to multiple qubit interactions, facilitated specifically by a new entanglement method which propagates the controlled-NOT (C-NOT) quantum gate.

Daniel D. Dorroh; Serkay Olmez; Jian-Ping Wang

2013-05-17T23:59:59.000Z

452

Next-generation magnetic nozzle prototype  

SciTech Connect

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project sought to develop a next-generation magnetic nozzle. The project engaged the fundamental physics of plasma- magnetic field interactions to attain plasma accelerator control that is significantly more advanced than the present state-of-the-art. Central to next-generation magnetic nozzle design and development is the ability to precisely predict the interaction of flowing magnetized plasma with self-generated and applied magnetic fields. This predictive capability must order physical processes in a way that preserves accuracy while allowing for the rapid evaluation of many different nozzle configurations. Large, ``off-the-shelf``, numerical codes are not well suited to nozzle design applications in that they lack the necessary non-ideal physics and are not well disposed to rapid design evaluation. For example, we know that both non-ideal magnetohydrodynamic effects, such as Hall drifts and finite ion- gyro-radius kinetics, are important constituents of magnetic nozzle performance. We built a special purpose code to allow system design.

Wagner, H.P.; Schoenberg, K.F.; Moses, R.W. Jr.; Gerwin, R.A.

1996-11-01T23:59:59.000Z

453

Magnetism Highlights| Neutron Science | ORNL  

NLE Websites -- All DOE Office Websites (Extended Search)

Magnetism Magnetism SHARE Magnetism Highlights 1-5 of 5 Results ARCS maps collaborative magnetic spin behavior in iron telluride December 01, 2011 - Researchers have long thought that magnetism and superconductivity are mutually exclusive. The former typically involves localized atomic electrons. The latter requires freely propagating, itinerant electrons. Unexpected Magnetic Excitations in Doped Insulator Surprise Researchers October 01, 2011 - When doping a disordered magnetic insulator material with atoms of a nonmagnetic material, the conventional wisdom is that the magnetic interactions between the magnetic ions in the material will be weakened. Neutron Analysis Reveals Unique Atomic-Scale Behavior of "Cobalt Blue" September 01, 2011 - Neutron scattering studies of "cobalt blue," a

454

Nuclear magnetic resonance offers new insights into Pu 239  

NLE Websites -- All DOE Office Websites (Extended Search)

Nuclear magnetic resonance offers new insights into Pu 239 Nuclear magnetic resonance offers new insights into Pu 239 Nuclear magnetic resonance offers new insights into Pu 239 Fingerprint of element found by LANL/Japanese team. May 29, 2012 How would the detonation of a nuclear energy source afffect an incoming asteroid? Georgios Koutroulakis and H. Yasuoka in the condensed-matter NMR lab at Los Alamos National Laboratory after having observed the magnetic resonance signal of Pu 239 for the first time. Get Expertise Scientist Eric Bauer Condensed Matter & Magnet Science Email Professor Hiroshi Yasuoka Japan Atomic Energy Agency "This discovery of the plutonium 239 magnetic resonance promises to revolutionize our understanding of plutonium solid state physics, chemistry, biology and materials science."

455

Nonlinear stability of magnetic islands in a rotating helical plasma  

Science Conference Proceedings (OSTI)

Coexistence of the forced magnetic reconnection by a resonant magnetic perturbation (RMP) and the curvature-driven tearing mode is investigated in a helical (stellarator) plasma rotated by helical trapped particle-induced neoclassical flows. A set of Rutherford-type equations of rotating magnetic islands and a poloidal flow evolution equation is revisited. Using the model, analytical expressions of criteria of spontaneous shrinkage (self-healing) of magnetic islands and sudden growth of locked magnetic islands (penetration of RMP) are obtained, where nonlinear saturation states of islands show bifurcation structures and hysteresis characteristics. Considering radial profile of poloidal flows across magnetic islands, it is found that the self-healing is driven by neoclassical viscosity even in the absence of micro-turbulence-induced anomalous viscosity. Effects of unfavorable curvature in stellarators are found to modify the critical values. The scalings of criteria are consistent with low-{beta} experiments in the large helical device.

Nishimura, S.; Toda, S.; Narushima, Y. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan); Yagi, M. [Japan Atomic Energy Agency, Rokkasho, Aomori 039-3212 (Japan)

2012-12-15T23:59:59.000Z

456

Magneto-electric Effect and Magnetic Charge  

E-Print Network (OSTI)

It is shown that both the electric and magnetic dipole moment vectors of hydrogen atom in the excited states with wave function $$ u_n^{(\\pm)} = {1\\over\\sqrt 2} [R_{n,n-1}(r) Y_{n-1,\\pm (n-2)}(\\theta\\phi) \\pm R_{n,n-2}(r) Y_{n-2,\\pm (n-2)}(\\theta\\phi)]$$ align themselves in the direction of an external uniform electric field which is characteristic of magneto-electric effect. These states are found to have magnetic charge $g={3n\\over (n-2)e}$ on account of this effect. This result is confirmed by an independent method. An experiment is suggested to fabricate these states and detect the magnetic charge. It ma be worth noting that inspite of many experimental searchs, magnetic charge, whose existence has been theorized both in electrodynamics and non-abelian gauge theories, none have been found so far, nor there exist any suggstion as to where these are to be found.

T. Pradhan

2003-12-10T23:59:59.000Z

457

Simultaneous ionization-excitation of helium to He ,,2p... magnetic sublevels by proton impact  

E-Print Network (OSTI)

-5698 Received 3 October 2001; published 12 December 2001 Experimental magnetic substate cross section ratios 0 ionization- excitation mechanism from the He(1s2 ) 1 S ground state to the final ionic state He (2p) 2 P0

Godunov, Alexander L.

458

BEPC-II Magnet Project | Superconducting Magnet Division  

NLE Websites -- All DOE Office Websites (Extended Search)

BEPC-II Magnet Project BEPC-II Magnet Project Project Overview The BEPC-II magnets are Interaction Region magnets to be used as part of an upgrade to the Beijing Electron Positron Collider. Two magnets will be produced, both of which will be inserted within the solenoidal detector at one of the collision points. Since the best use of the quadrupole focusing in this case requires placing the magnet as close to the collision point as possible, these magnets will be used within the magnetic field of the detector. This constrains the materials that can be used for construction to only non-magnetic materials. It also places severe demands on the structure of the magnet and it's holding supports due to the reaction forces between the solenoid and the magnet. To create the coil pattern for the final magnet, the coils will be

459

Multiscale dynamics of solar magnetic structures  

E-Print Network (OSTI)

Multiscale topological complexity of solar magnetic field is among the primary factors controlling energy release in the corona, including associated processes in the photospheric and chromospheric boundaries. We present a new approach for analyzing multiscale behavior of the photospheric magnetic flux underlying this dynamics as depicted by a sequence of high-resolution solar magnetograms. The approach involves two basic processing steps: (1) identification of timing and location of magnetic flux origin and demise events (as defined by DeForest et al., 2007) by tracking spatiotemporal evolution of unipolar and bipolar photospheric regions, and (2) analysis of collective behavior of the detected magnetic events using a generalized version of Grassberger - Procaccia correlation integral algorithm. The scale-free nature of the developed algorithms makes it possible to characterize the dynamics of the photospheric network across a wide range of distances and relaxation times. Three types of photospheric conditions are considered to test the method: a quiet photosphere, a solar active region (NOAA 10365) in a quiescent non-flaring state, and the same active region during a period of M-class flares. The results obtained show (1) the presence of a topologically complex asymmetrically fragmented magnetic network in the quiet photosphere driven by meso- and supergranulation, (2) the formation of non-potential magnetic structures with complex polarity separation lines inside the active region, and (3) statistical signatures of canceling bipolar magnetic structures coinciding with flaring activity in the active region. Each of these effects can represent an unstable magnetic configuration acting as an energy source for coronal dissipation and heating.

Vadim M. Uritsky; Joseph M. Davila

2011-11-21T23:59:59.000Z

460

MAXIMIZING MAGNETIC ENERGY STORAGE IN THE SOLAR CORONA  

Science Conference Proceedings (OSTI)

The energy that drives solar eruptive events such as coronal mass ejections (CMEs) almost certainly originates in coronal magnetic fields. Such energy may build up gradually on timescales of days or longer before its sudden release in an eruptive event, and the presence of free magnetic energy capable of rapid release requires nonpotential magnetic fields and associated electric currents. For magnetic energy to power a CME, that energy must be sufficient to open the magnetic field to interplanetary space, to lift the ejecta against solar gravity, and to accelerate the material to speeds of typically several hundred km s{sup -1}. Although CMEs are large-scale structures, many originate from relatively compact active regions on the solar surface-suggesting that magnetic energy storage may be enhanced when it takes place in smaller magnetic structures. This paper builds on our earlier work exploring energy storage in large-scale dipolar and related bipolar magnetic fields. Here we consider two additional cases: quadrupolar fields and concentrated magnetic bipoles intended to simulate active regions. Our models yield stored energies whose excess over that of the corresponding open field state can be greater than 100% of the associated potential field energy; this contrasts with maximum excess energies of only about 20% for dipolar and symmetric bipolar configurations. As in our previous work, energy storage is enhanced when we surround a nonpotential field with a strong overlying potential field that acts to 'hold down' the nonpotential flux as its magnetic energy increases.

Wolfson, Richard; Drake, Christina; Kennedy, Max, E-mail: wolfson@middlebury.edu [Department of Physics, Middlebury College, Middlebury, VT 05753 (United States)

2012-05-01T23:59:59.000Z

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461

Passive magnetic bearing configurations  

Science Conference Proceedings (OSTI)

A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

Post, Richard F. (Walnut Creek, CA)

2011-01-25T23:59:59.000Z

462

EXOTIC MAGNETS FOR ACCELERATORS.  

SciTech Connect

Over the last few years, several novel magnet designs have been introduced to meet the requirements of new, high performance accelerators and beam lines. For example, the FAIR project at GSI requires superconducting magnets ramped at high rates ({approx} 4 T/s) in order to achieve the design intensity. Magnets for the RIA and FAIR projects and for the next generation of LHC interaction regions will need to withstand high doses of radiation. Helical magnets are required to maintain and control the polarization of high energy protons at RHIC. In other cases, novel magnets have been designed in response to limited budgets and space. For example, it is planned to use combined function superconducting magnets for the 50 GeV proton transport line at J-PARC to satisfy both budget and performance requirements. Novel coil winding methods have been developed for short, large aperture magnets such as those used in the insertion region upgrade at BEPC. This paper will highlight the novel features of these exotic magnets.

WANDERER, P.

2005-09-18T23:59:59.000Z

463

Superconducting Magnet Division  

NLE Websites -- All DOE Office Websites (Extended Search)

3 - 6/13/06 3 - 6/13/06 Superconducting Magnet Division S&T Committee Program Review June 22-23, 2006 Conference Room A, Bldg. 725, BNL DRAFT AGENDA Thursday, June 22 0830 Executive Session to address the charge S. Aronson (25 min) 0855 Welcome S. Aronson (5 min) 0900 Superconducting Magnet Division Status & M. Harrison (45 + 15 min) Issues - mission statement, core competencies, themes, program, problems, etc. 1000 Themes - Nb3Sn, HTS, Direct wind, Accelerator integration, P. Wanderer (20 + 10 min) rapid cycling Core Competencies 1030 Superconducting Materials A. Ghosh (20 + 5 min) 1055 Break 1110 Magnetic Design R. Gupta (20 + 5 min) 1135 Magnet Construction M. Anerella (20 + 5 min) 1200 Magnet Testing G. Ganetis (20 + 5 min)

464

Cool Magnetic Molecules  

NLE Websites -- All DOE Office Websites (Extended Search)

Cool Magnetic Molecules Print Cool Magnetic Molecules Print Certain materials are known to heat up or cool down when they are exposed to a changing magnetic field. This is known as the magnetocaloric effect. All magnetic materials exhibit this effect, but in most cases, it is too small to be technologically useful. Recently, however, the search for special molecules with a surprisingly large capacity to keep cool has heated up, driven by environmental and cost considerations as well as by recent improvements in our ability to design, assemble, and probe the structure and chemistry of small molecules. An international collaboration of researchers from Spain, Scotland, and the U.S. has utilized ALS Beamline 11.3.1 (small-molecule crystallography) to characterize the design of such "molecular coolers." The work targets the synthesis of molecular cluster compounds containing many unpaired electrons ("nanomagnets") for applications involving enhanced magnetic refrigeration at very low temperatures.

465

Cool Magnetic Molecules  

NLE Websites -- All DOE Office Websites (Extended Search)

Cool Magnetic Molecules Print Cool Magnetic Molecules Print Certain materials are known to heat up or cool down when they are exposed to a changing magnetic field. This is known as the magnetocaloric effect. All magnetic materials exhibit this effect, but in most cases, it is too small to be technologically useful. Recently, however, the search for special molecules with a surprisingly large capacity to keep cool has heated up, driven by environmental and cost considerations as well as by recent improvements in our ability to design, assemble, and probe the structure and chemistry of small molecules. An international collaboration of researchers from Spain, Scotland, and the U.S. has utilized ALS Beamline 11.3.1 (small-molecule crystallography) to characterize the design of such "molecular coolers." The work targets the synthesis of molecular cluster compounds containing many unpaired electrons ("nanomagnets") for applications involving enhanced magnetic refrigeration at very low temperatures.