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1

Dynamics of Magnetized Vortex Tubes in the Solar Chromosphere  

E-Print Network (OSTI)

We use 3D radiative MHD simulations to investigate the formation and dynamics of small-scale (less than 0.5 Mm in diameter) vortex tubes spontaneously generated by turbulent convection in quiet-Sun regions with initially weak mean magnetic fields. The results show that the vortex tubes penetrate into the chromosphere and substantially affect the structure and dynamics of the solar atmosphere. The vortex tubes are mostly concentrated in intergranular lanes and are characterized by strong (near sonic) downflows and swirling motions that capture and twist magnetic field lines, forming magnetic flux tubes that expand with height and which attain magnetic field strengths ranging from 200 G in the chromosphere to more than 1 kG in the photosphere. We investigate in detail the physical properties of these vortex tubes, including thermodynamic properties, flow dynamics, and kinetic and current helicities, and conclude that magnetized vortex tubes provide an important path for energy and momentum transfer from the con...

Kitiashvili, I N; Mansour, N N; Wray, A A

2012-01-01T23:59:59.000Z

2

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 X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation Print Wednesday, 25 November 2009 00:00 Magnetic...

3

Magnetic Vortex Dynamics Roman ANTOS1  

E-Print Network (OSTI)

background of the research topic and briefly list the analytical and experimental approaches dealing interest due to their possible applications in high density magnetic data storage,3) magnetic field sensors background of the research topic according to the description by Hubert and Schafer6) (§2) and briefly

Otani, Yoshichika

4

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.

5

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.

6

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.

7

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.

8

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.

9

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.

10

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.

11

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

12

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.

13

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.

14

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.

15

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.

16

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 In micrometer-sized magnetic thin films, the magnetization typically adopts an in-plane, circular configuration known...

17

Tunable negligible-loss energy transfer between dipolar-coupled magnetic disks by stimulated vortex gyration  

E-Print Network (OSTI)

structure of magnetic vortex cores. Science 298, 577– Park,Magnetic vortex core observation in circular dots of Permalloy. Science

Jung, Hyunsung

2014-01-01T23:59:59.000Z

18

Dynamic decay of a single vortex into vortex-antivortex pairs  

SciTech Connect

A variety of metastable states, including vortices, antivortices, and their combinations, is typical for magnetically soft, thin films and patterned structures. The physics of individual spin vortices in patterned structures has been rather extensively explored. In contrast, there are few studies of the vortex–antivortex–vortex (v-av-v) system, in part because the configuration is rather challenging to obtain experimentally. We demonstrate herein how a recently proposed resonant-spin-ordering technique can be used to induce the dynamic decay of a single vortex into v-av states in elongated elements. The approach is based on first driving the system from the linear regime of constant vortex gyrations to the non-linear regime of vortex-core reversals at a fixed excitation frequency, and then subsequently reducing the excitation field back to the linear regime. This procedure stabilizes the system into a v-av-v state that is completely decoupled from the initialization excitation frequency. The newly acquired state is stable in remanence. The dynamic response of this system is expected to demonstrate a number of collective modes, depending on the combination of the vortex core polarities, and/or the excitation field direction, and, hence, is of interest for future studies.

Lendínez, Sergi [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Universidad Barcelona, Departamento Fisica Fonamental, E-08028 Barcelona (Spain); Jain, Shikha; Novosad, Valentyn, E-mail: novosad@anl.gov; Fradin, Frank Y.; Pearson, John E. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Tejada, Javier [Universidad Barcelona, Departamento Fisica Fonamental, E-08028 Barcelona (Spain); Bader, Samuel D. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2014-05-07T23:59:59.000Z

19

Symmetry breaking in the formation of magnetic vortex states in a permalloy nanodisk  

E-Print Network (OSTI)

structure of magnetic vortex cores. Science 298, 6. Fischer,Magnetic Material Center, National Institute for Materials Science (Magnetic vortex core observation in circular dots of Permalloy. Science

Im, Mi-Young

2014-01-01T23:59:59.000Z

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 "dynamic magnetic vortex" 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

Low-temperature vortex dynamics in a high-temperature superconductor  

Science Journals Connector (OSTI)

Magnetic-field gradients in the mixed state of a type-II superconductor are studied using Tl205 nuclear magnetic resonance (NMR) on Tl2Ba2Ca2Cu3O10+?. An anomalous peak was observed in the temperature dependence of the transverse relaxation rate at T/Tc?0.25. We attribute this behavior to magnetic-field flucutations from vortex dynamics. We interpret this behavior as a crossover of the principal time scale for vortex dynamics with that of the NMR experiment, approximately 100 ?s. The temperature dependence of this time scale is discussed.

Y.-Q. Song; S. Tripp; W. P. Halperin; L. Tonge; T. J. Marks

1994-12-01T23:59:59.000Z

22

Vortex-vacancy interactions in two-dimensional easy-plane magnets G. M. Wysin  

E-Print Network (OSTI)

Vortex-vacancy interactions in two-dimensional easy-plane magnets G. M. Wysin Department of Physics of a magnetic vacancy site on a nearby magnetic vortex are analyzed on square, hexagonal and triangular lattices. When the vortex is centered on a vacancy, the critical anisotropies where the stable vortex structure

Wysin, Gary

23

High-frequency vortex dynamics and dissipation of high-temperature superconductors  

Science Journals Connector (OSTI)

The high-frequency vortex dynamics of high-temperature superconductors near the flux-line depinning threshold is investigated based on a thermally activated flux-flow (TAFF) model. Dissipation due to vortex motion driven by a microwave electromagnetic field is studied as a function of the frequency, temperature, dc magnetic field, and microwave power. The generalized TAFF model is also compared to the conventional flux-creep theory and is found qualitatively consistent.

N.-C. Yeh

1991-01-01T23:59:59.000Z

24

Ubiquitous Solar Eruptions Driven by Magnetized Vortex Tubes  

E-Print Network (OSTI)

The solar surface is covered by high-speed jets transporting mass and energy into the solar corona and feeding the solar wind. The most prominent of these jets have been known as spicules. However, the mechanism initiating these eruptions events is still unknown. Using realistic numerical simulations we find that small-scale eruptions are produced by ubiquitous magnetized vortex tubes generated by the Sun's turbulent convection in subsurface layers. The swirling vortex tubes (resembling tornadoes) penetrate into the solar atmosphere, capture and stretch background magnetic field, and push surrounding material up, generating quasiperiodic shocks. Our simulations reveal a complicated high-speed flow patterns, and thermodynamic and magnetic structure in the erupting vortex tubes. We found that the eruptions are initiated in the subsurface layers and are driven by the high-pressure gradients in the subphotosphere and photosphere, and by the Lorentz force in the higher atmosphere layers.

Kitiashvili, I N; Lele, S K; Mansour, N N; Wray, A A

2013-01-01T23:59:59.000Z

25

Dynamic switching of the circulation in tapered magnetic nanodisks  

E-Print Network (OSTI)

spin structure of magnetic vortex cores. Science 298, 577 (Magnetic vortex core observation in circular dots of permalloy. Science

Uhlir, V.

2014-01-01T23:59:59.000Z

26

UBIQUITOUS SOLAR ERUPTIONS DRIVEN BY MAGNETIZED VORTEX TUBES  

SciTech Connect

The solar surface is covered by high-speed jets transporting mass and energy into the solar corona and feeding the solar wind. The most prominent of these jets have been known as spicules. However, the mechanism initiating these eruption events is still unknown. Using realistic numerical simulations we find that small-scale eruptions are produced by ubiquitous magnetized vortex tubes generated by the Sun's turbulent convection in subsurface layers. The swirling vortex tubes (resembling tornadoes) penetrate into the solar atmosphere, capture and stretch background magnetic field, and push the surrounding material up, generating shocks. Our simulations reveal complicated high-speed flow patterns and thermodynamic and magnetic structure in the erupting vortex tubes. The main new results are: (1) the eruptions are initiated in the subsurface layers and are driven by high-pressure gradients in the subphotosphere and photosphere and by the Lorentz force in the higher atmosphere layers; (2) the fluctuations in the vortex tubes penetrating into the chromosphere are quasi-periodic with a characteristic period of 2-5 minutes; and (3) the eruptions are highly non-uniform: the flows are predominantly downward in the vortex tube cores and upward in their surroundings; the plasma density and temperature vary significantly across the eruptions.

Kitiashvili, I. N.; Kosovichev, A. G. [Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States); Lele, S. K.; Mansour, N. N.; Wray, A. A., E-mail: irinasun@stanford.edu [Center for Turbulence Research, Stanford University, Stanford, CA 94305 (United States)

2013-06-10T23:59:59.000Z

27

Development of vortex state in circular magnetic nanodots: Theory and experiment RID A-9247-2009  

E-Print Network (OSTI)

magnetic vortex. The vortex-core diameter is controlled by competing magnetic energy contributions. For 20-nm-thick Fe dots, the values of the critical diameter (58-60 nm) and the vortex core (16-19 nm) are in very good agreement between the different...

Mejia-Lopez, J.; Altbir, D.; Landeros, P.; Escrig, J.; Romero, A. H.; Roshchin, Igor V.; Li, C-P; Fitzsimmons, M. R.; Batlle, X.; Schuller, Ivan K.

2010-01-01T23:59:59.000Z

28

Vortex dynamics in 4 Banavara N. Shashikanth  

E-Print Network (OSTI)

during the interaction of a pair of counter-rotating vortices Phys. Fluids 24, 014107 (2012) The onset of oblique vortex shedding behind a heated circular cylinder in laminar wake regime Phys. Fluids 24, 011701 fluids Phys. Fluids 23, 115106 (2011) Asymptotic properties of wall-induced chaotic mixing in point

Shashikanth, Banavara N.

29

Laboratory Analysis of Vortex Dynamics For Shallow Tidal Inlets  

E-Print Network (OSTI)

LABORATORY ANALYSIS OF VORTEX DYNAMICS FOR SHALLOW TIDAL INLETS A Thesis by KERRI ANN WHILDEN Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements for the degree of MASTER OF SCIENCE August 2009... Major Subject: Ocean Engineering LABORATORY ANALYSIS OF VORTEX DYNAMICS FOR SHALLOW TIDAL INLETS A Thesis by KERRI ANN WHILDEN Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements for the degree...

Whilden, Kerri Ann

2010-10-12T23:59:59.000Z

30

Resonant amplification of vortex-core oscillations by coherent magnetic-field pulses  

E-Print Network (OSTI)

structure of magnetic vortex cores. Science 298, 577–580 (D. A. et al. Magnetic domain-wall logic. Science 309, 1688 (L. Magnetic domain-wall racetrack memory. Science 320, 190–

Yu, Young-Sang

2014-01-01T23:59:59.000Z

31

Magnetization reversal via single and double vortex states in submicron Permalloy ellipses P. Vavassori,1  

E-Print Network (OSTI)

Magnetization reversal via single and double vortex states in submicron Permalloy ellipses P University, Ithaca, New York, USA Received December 5, 2003; published 3 June 2004 The magnetization reversal of the magnetic field and to occur via the formation of one or two vortices; the one vortex state is nucleated

Metlushko, Vitali

32

The effect of surface tension on the Moore singularity of vortex sheet dynamics  

E-Print Network (OSTI)

The effect of surface tension on the Moore singularity of vortex sheet dynamics F. de la Hoz , M's singularities by surface tension in the evolution of vortex sheets and its dependence on Weber number (which is inversely proportional to surface tension coefficient). The curvature of the vortex sheet, instead

Fontelos, Marco

33

Vortex driven flame dynamics and combustion instability  

E-Print Network (OSTI)

Combustion instability in premixed combustors mostly arises due to the coupling between heat release rate dynamics and system acoustics. It is crucial to understand the instability mechanisms to design reliable, high ...

Altay, Hurrem Murat

2005-01-01T23:59:59.000Z

34

Low-amplitude magnetic vortex core reversal by non-linear interaction between azimuthal spin waves and the vortex gyromode  

SciTech Connect

We show, by experiments and micromagnetic simulations in vortex structures, that an active “dual frequency” excitation of both the sub-GHz vortex gyromode and multi-GHz spin waves considerably changes the frequency response of spin wave mediated vortex core reversal. Besides additional minima in the switching threshold, a significant broadband reduction of the switching amplitudes is observed, which can be explained by non-linear interaction between the vortex gyromode and the spin waves. We conclude that the well known frequency spectra of azimuthal spin waves in vortex structures are altered substantially, when the vortex gyromode is actively excited simultaneously.

Sproll, Markus; Noske, Matthias; Kammerer, Matthias; Dieterle, Georg; Weigand, Markus; Stoll, Hermann; Schütz, Gisela [Max Planck Institute for Intelligent Systems (formerly MPI for Metals Research), Heisenbergstr. 3, 70569 Stuttgart (Germany)] [Max Planck Institute for Intelligent Systems (formerly MPI for Metals Research), Heisenbergstr. 3, 70569 Stuttgart (Germany); Bauer, Hans; Gangwar, Ajay; Woltersdorf, Georg; Back, Christian H. [Department of Physics, University of Regensburg, Universitätsstr. 31, 93040 Regensburg (Germany)] [Department of Physics, University of Regensburg, Universitätsstr. 31, 93040 Regensburg (Germany)

2014-01-06T23:59:59.000Z

35

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

36

Dynamical mass of a quantum vortex in a Josephson junction array  

SciTech Connect

The real-time response to a small external perturbation of a vortex in a quantum Josephson junction array, with long-range Coulomb interaction between Cooper pairs, is analyzed. While the static damping is zero for vortex velocities below some threshold value v{sub th} (which implies the possibility of ballistic motion), a dynamical friction due to the coupling to the plasma oscillations is always present for frequencies higher than a given threshold {omega}{sub th}. The latter approaches zero when the velocity increases to v{sub th}. However, radiative dissipation of the vortex affects the threshold for ballistic motion. We discuss the conditions under which a mass can be defined for the vortex as a quantum particle. {copyright} {ital 1997} {ital The American Physical Society}

Eckern, U. [Institut fuer Physik, Universitaet Augsburg, D-86135 Augsburg (Germany)] [Institut fuer Physik, Universitaet Augsburg, D-86135 Augsburg (Germany); Luciano, G.; Tagliacozzo, A. [Dipartimento di Scienze Fisiche, Universita di Napoli, Mostra dOltremare Pad. 19, I-80125 Napoli (Italy)] [Dipartimento di Scienze Fisiche, Universita di Napoli, Mostra dOltremare Pad. 19, I-80125 Napoli (Italy); [Istituto Nazionale di Fisica della Materia (INFM), I-16152 Genova (Italy)

1997-12-01T23:59:59.000Z

37

Kelvin-Helmholtz instability in a current-vortex sheet at a 3D magnetic null  

SciTech Connect

We report here, for the first time, an observed instability of a Kelvin-Helmholtz nature occurring in a fully three-dimensional (3D) current-vortex sheet at the fan plane of a 3D magnetic null point. The current-vortex layer forms self-consistently in response to foot point driving around the spine lines of the null. The layer first becomes unstable at an intermediate distance from the null point, with the instability being characterized by a rippling of the fan surface and a filamentation of the current density and vorticity in the shear layer. Owing to the 3D geometry of the shear layer, a branching of the current filaments and vortices is observed. The instability results in a mixing of plasma between the two topologically distinct regions of magnetic flux on either side of the fan separatrix surface, as flux is reconnected across this surface. We make a preliminary investigation of the scaling of the system with the dissipation parameters. Our results indicate that the fan plane separatrix surface is an ideal candidate for the formation of current-vortex sheets in complex magnetic fields and, therefore, the enhanced heating and connectivity change associated with the instabilities of such layers.

Wyper, P. F. [School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH (United Kingdom); Pontin, D. I. [Division of Mathematics, University of Dundee, Dundee DD1 4HN (United Kingdom)

2013-03-15T23:59:59.000Z

38

Quantum dynamics of a vortex in a Josephson junction  

SciTech Connect

We investigate the tunneling character of vortex in an asymmetrical potential well with a finite barrier by using the periodic instanton method. We obtain the total decay rate which is valid for the entire range of temperature and show how it reduces to the appropriate results for the classical thermal activation at high temperatures, the thermally assisted tunneling at intermediate temperatures, and the pure quantum tunneling at low temperature. We can even give the exact definition of the 'crossover' temperature and find experimental data to support our theoretical analysis.

Li Hong; Liu Wuming [Joint Laboratory of Advanced Technology in Measurements, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Shen Shunqing [Department of Physics, University of Hong Kong, Pokfulam Road, Hong Kong (China); Liang Jiuqing [Institute of Theoretical Physics, Shanxi University, Taiyuan, Shanxi 030006 (China)

2005-07-01T23:59:59.000Z

39

Plasma resonance at low magnetic fields as a probe of vortex line meandering in layered superconductors  

Science Journals Connector (OSTI)

We consider the magnetic-field dependence of the plasma resonance frequency in pristine and in irradiated Bi2Sr2CaCu2O8 crystals near Tc. At low magnetic fields we relate linear in field corrections to the plasma frequency to the average distance between the pancake vortices in the neighboring layers (wandering length). We calculate the wandering length in the case of thermal wiggling of vortex lines, taking into account both Josephson and magnetic interlayer coupling of pancakes. Analyzing experimental data, we found that (i) the wandering length becomes comparable with the London penetration depth near Tc and (ii) at small melting fields (line liquid phase in this field range. We also found that pinning by columnar defects affects weakly the field dependence of the plasma resonance frequency near Tc.

L. N. Bulaevskii; A. E. Koshelev; V. M. Vinokur; M. P. Maley

2000-02-01T23:59:59.000Z

40

Plasma resonance at low magnetic fields as a probe of vortex line meandering in layered superconductors  

E-Print Network (OSTI)

We consider the magnetic field dependence of the plasma resonance frequency in pristine and in irradiated Bi$_2$Sr$_2$CaCu$_2$O$_8$ crystals near $T_c$. At low magnetic fields we relate linear in field corrections to the plasma frequency to the average distance between the pancake vortices in the neighboring layers (wandering length). We calculate the wandering length in the case of thermal wiggling of vortex lines, taking into account both Josephson and magnetic interlayer coupling of pancakes. Analyzing experimental data, we found that (i) the wandering length becomes comparable with the London penetration depth near T$_{c}$ and (ii) at small melting fields ($line liquid phase in this field range. We also found that pinning by columnar defects affects weakly the field dependence of the plasma resonance frequency near $T_c$.

L. N. Bulaevskii; A. E. Koshelev; V. M. Vinokur; M. P. Maley

1999-07-29T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

Vortex Dynamics for the Ginzburg-Landau-Schrödinger Equation  

E-Print Network (OSTI)

The initial value problem for the Ginzburg-Landau-Schr\\"odinger equation is examined in the $\\epsilon \\rightarrow 0$ limit under two main assumptions on the initial data $\\phi^\\epsilon$. The first assumption is that $\\phi^\\epsilon$ exhibits $m$ distinct vortices of degree $\\pm 1$; these are described as points of concentration of the Jacobian $[J\\phi^\\epsilon]$ of $\\phi^\\epsilon$. Second, we assume energy bounds consistent with vortices at the points of concentration. Under these assumptions, we identify ``vortex structures'' in the $\\epsilon \\rightarrow 0$ limit of $\\phi^\\epsilon$ and show that these structures persist in the solution $u^\\epsilon(t)$ of $GLS_\\epsilon$. We derive ordinary differential equations which govern the motion of the vortices in the $\\epsilon \\rightarrow 0$ limit. The limiting system of ordinary differential equations is a Hamitonian flow governed by the renormalized energy of Bethuel, Brezis and H\\'elein. Our arguments rely on results about the structural stability of vortices which are proved in a separate paper.

James Ellis Colliander; Robert L. Jerrard

1997-12-12T23:59:59.000Z

42

Novel vortex dynamics in untwinned YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} single crystals  

SciTech Connect

Magnetotransport measurements on a clean, untwinned YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} single crystal show that the vortex dynamics at temperatures just below the vortex lattice melting transition are highly dependent on the type of modulation of the probing current. While in the case of DC current the flux flow is disordered, the {open_quotes}shaking{close_quotes} of the vortex lattice by a square-wave current leads to a more uniform vortex motion. A small asymmetry ({approximately}10%) in the durations of the positive and negative parts of the square-wave period induces periodical oscillations of the voltage response amplitude. The period of oscillations ({approximately}100 s) is the same order of magnitude as the time needed for vortices to cross the sample (transit time). The authors relate the observed voltage oscillations to a periodically ordered vortex motion.

Gordeev, S.N.; Oussena, M.; Pinfold, S.; Langan, R.M. [Univ. of Southampton (United Kingdom)] [and others

1996-12-01T23:59:59.000Z

43

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.

44

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.

45

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.

46

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.

47

Incoherent interaction of propagating spin waves with precessing magnetic moments  

E-Print Network (OSTI)

The magnetization dynamics of the magnetic vortex state occurring in response to subnanosecond transitions of the externally applied magnetic field was investigated in Ni[subscript 80]Fe[subscript 20](12?nm)/Ir[subscript ...

Ross, Caroline A.

48

Moving vortex phases, dynamical symmetry breaking, and jamming for vortices in honeycomb pinning arrays  

SciTech Connect

We show using numerical simulations that vortices in honeycomb pinning arrays can exhibit a remarkable variety of dynamical phases that are distinct from those found for triangular and square pinning arrays. In the honeycomb arrays, it is possible for the interstitial vortices to form dimer or higher n-mer states which have an additional orientational degree of freedom that can lead to the formation of vortex molecular crystals. For filling fractions where dimer states appear, a dynamical symmetry breaking can occur when the dimers flow in one of two possible alignment directions. This leads to transport in the direction transverse to the applied drive. We show that dimerization produces distinct types of moving phases which depend on the direction of the driving force with respect to the pinning lattice symmetry. When the dimers are driven along certain directions, a reorientation of the dimers can produce a jamming phenomenon which results in a strong enhancement in the critical depinning force. The jamming can also cause unusual effects such as an increase in the critical depinning force when the size of the pinning sites is reduced.

Reichhardt, Charles [Los Alamos National Laboratory; Reichhardt, Cynthia [Los Alamos National Laboratory

2008-01-01T23:59:59.000Z

49

Dynamics of magnetic nanoparticle suspensions  

E-Print Network (OSTI)

We study the dynamics of a suspension of magnetic nanoparticles. Their relaxation times are strongly size-dependent. The dominant mode of relaxation is also governed by the size of the particles. As a result the dynamics is greatly altered due to polydispersity in the sample. We study the effect of polydispersity on the response functions. These exhibit significant changes as the parameters characterizing polydispersity are varied. We also provide a procedure to extract the particle size distribution in a polydisperse sample using Cole-Cole plots. Further the presence of attractive interactions causes aggregation of particles leading to the formation of clusters. Repulsive interactions along with thermal disorder not only hinder aggregation, but also introduce the possibility of removal of particles or "fragmentation" from clusters. The competing mechanisms of aggregation and fragmentation yield a distribution of cluster sizes in the steady-state. We attempt to understand the formation of clusters and their distributions using a model incorporating the phenomena of aggregation and fragmentation. Scaling forms for quantities of interest have been obtained. Finally we compare our numerical results with experimental data. These comparisons are satisfactory.

Vanchna Singh; Varsha Banerjee; Manish Sharma

2012-08-20T23:59:59.000Z

50

LANGEVIN DYNAMICS OF THE TWO STAGE MELTING TRANSITION OF VORTEX MATTER IN Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} IN THE PRESENCE OF STRAIGHT AND OF TILTED COLUMNAR DEFECTS  

SciTech Connect

In this paper we use London Langevin molecular dynamics simulations to investigate the vortex matter melting transition in the highly anisotropic high-temperature superconductor material Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}#14; in the presence of low concentration of columnar defects (CDs). We reproduce with further details our previous results obtained by using Multilevel Monte Carlo simulations that showed that the melting of the nanocrystalline vortex matter occurs in two stages: a first stage melting into nanoliquid vortex matter and a second stage delocalization transition into a homogeneous liquid. Furthermore, we report on new dynamical measurements in the presence of a current that identifies clearly the irreversibility line and the second stage delocalization transition. In addition to CDs aligned along the c-axis we also simulate the case of tilted CDs which are aligned at an angle with respect to the applied magnetic field. Results for CDs tilted by 45{degree} with respect to c-axis show that the locations of the melting and delocalization transitions are not affected by the tilt when the ratio of flux lines to CDs remains constant. On the other hand we argue that some dynamical properties and in particular the position of the irreversibility line should be affected.

GOLDSCHMIDT, YADIN Y.; LIU, Jin-Tao

2007-08-07T23:59:59.000Z

51

Effects of trailing edge flap dynamic deployment on blade-vortex interactions  

E-Print Network (OSTI)

A theoretical and experimental investigation is undertaken to determine the effects of an actively deployable trailing edge flap on the disturbances created during blade-vortex interactions (BVI). The theoretical model consists of an unsteady panel...

Nelson, Carter T.

2012-06-07T23:59:59.000Z

52

Control of magnetic vortex chirality in square ring micromagnets Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 and Materials Science  

E-Print Network (OSTI)

Control of magnetic vortex chirality in square ring micromagnets A. Libála Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 and Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 M. Grimsditch Materials Science Division, Argonne National Laboratory

Metlushko, Vitali

53

Anisotropic superconductivity and vortex dynamics in magnetially coupled F/S and F/S/F hybrids.  

SciTech Connect

Magnetically coupled superconductor-ferromagnet hybrids offer advanced routes for nanoscale control of superconductivity. Magnetotransport characteristics and scanning tunneling microscopy images of vortex structures in superconductor-ferromagnet hybrids reveal rich superconducting phase diagrams. Focusing on a particular combination of a ferromagnet with a well-ordered periodic magnetic domain structure with alternating out-of-plane component of magnetization, and a small coherence length superconductor, we find directed nucleation of superconductivity above the domain wall boundaries. We show that near the superconductor-normal state phase boundary the superconductivity is localized in narrow mesoscopic channels. In order to explore the Abrikosov flux line ordering in F/S hybrids, we use a combination of scanning tunneling microscopy and Ginzburg-Landau simulations. The magnetic stripe domain structure induces periodic local magnetic induction in the superconductor, creating a series of pinning-anti-pinning channels for externally added magnetic flux quanta. Such laterally confined Abrikosov vortices form quasi-1D arrays (chains). The transitions between multichain states occur through propagation of kinks at the intermediate fields. At high fields we show that the system becomes nonlinear due to a change in both the number of vortices and the confining potential. In F/S/F hybrids we demonstrate the evolution of the anisotropic conductivity in the superconductor that is magnetically coupled with two adjacent ferromagnetic layers. Stripe magnetic domain structures in both F-layers are aligned under each other, resulting in a directional superconducting order parameter in the superconducting layer. The conductance anisotropy strongly depends on the period of the magnetic domains and the strength of the local magnetization. The anisotropic conductivity of up to three orders of magnitude can be achieved with a spatial critical temperature modulation of 5% of T{sub c}. Induced anisotropic properties in the F/S and F/S/F hybrids have a potential for future application in switching and nonvolatile memory elements operating at low temperatures.

Karapetrov, G.; Belkin, A.; Iavarone, M.; Fedor, J.; Novosad, V.; Milosevic, M. V.; Peeters, F. M. (Materials Science Division); (Illinois Inst. of Tech.); (Temple Univ.); (Slovak Academy of Sciences); (Univ. Antwerpen)

2011-01-01T23:59:59.000Z

54

Nuclear Magnetic Resonance Studies of Macroscopic Morphology and Dynamics  

E-Print Network (OSTI)

Applications in Materials Magnetic Science, Agriculture andApplications in Materials Magnetic Science, Agriculture andMagnetic Resonance Studies of Macroscopic Morphology and Dynamics Geoffrey Alden Barrali Department of Chemistry University of California, Berkeley and Materials Sciences

Barrall, G.A.

2010-01-01T23:59:59.000Z

55

Vortex Structure in Charged Condensate  

E-Print Network (OSTI)

We study magnetic fields in the charged condensate that we have previously argued should be present in helium-core white dwarf stars. We show that below a certain critical value the magnetic field is entirely expelled from the condensate, while for larger values it penetrates the condensate within flux-tubes that are similar to Abrikosov vortex lines; yet higher fields lead to the disruption of the condensate. We find the solution for the vortex lines in both relativistic and nonrelativistic theories that exhibit the charged condensation. We calculate the energy density of the vortex solution and the values of the critical magnetic fields. The minimum magnetic field required for vortices to penetrate the helium white dwarf cores ranges from roughly 10^7 to 10^9 Gauss. Fields of this strength have been observed in white dwarfs. We also calculate the London magnetic field due to the rotation of a dwarf star and show that its value is rather small.

Gabadadze, Gregory

2009-01-01T23:59:59.000Z

56

Vortex Structure in Charged Condensate  

E-Print Network (OSTI)

We study magnetic fields in the charged condensate that we have previously argued should be present in helium-core white dwarf stars. We show that below a certain critical value the magnetic field is entirely expelled from the condensate, while for larger values it penetrates the condensate within flux-tubes that are similar to Abrikosov vortex lines; yet higher fields lead to the disruption of the condensate. We find the solution for the vortex lines in both relativistic and nonrelativistic theories that exhibit the charged condensation. We calculate the energy density of the vortex solution and the values of the critical magnetic fields. The minimum magnetic field required for vortices to penetrate the helium white dwarf cores ranges from roughly 10^7 to 10^9 Gauss. Fields of this strength have been observed in white dwarfs. We also calculate the London magnetic field due to the rotation of a dwarf star and show that its value is rather small.

Gregory Gabadadze; Rachel A. Rosen

2009-05-14T23:59:59.000Z

57

Analysis of Vortex Dynamics of Lateral Circulation in a Straight Tidal Estuary  

Science Journals Connector (OSTI)

The dynamics associated with lateral circulation in a tidally driven estuarine channel is analyzed on the basis of streamwise vorticity. Without rotational effects, differential advection and diffusive boundary mixing produce two counterrotating ...

Ming Li; Peng Cheng; Robert Chant; Arnoldo Valle-Levinson; Kim Arnott

2014-10-01T23:59:59.000Z

58

Vortex reconnections between coreless vortices in binary condensates  

SciTech Connect

Vortex reconnections plays an important role in the turbulent flows associated with the superfluids. To understand the dynamics, we examine the reconnections of vortex rings in the superfluids of dilute atomic gases confined in trapping potentials using Gross-Petaevskii equation. Further more we study the reconnection dynamics of coreless vortex rings, where one of the species can act as a tracer.

Gautam, S. [Indian Institute of Science, Bangalore-560 012 (India); Suthar, K.; Angom, D. [Physical Research Laboratory, Ahmedabad-380 009 (India)

2014-02-11T23:59:59.000Z

59

Understanding Nanoscale Magnetization Dynamics Gregory S. Boebinger...  

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

exhibit slow relaxation upon removal from a polarizing magnetic field, referred to as single-molecule magnets (SMMs), are of considerable interest in terms of their potential...

60

Vortex properties in superconducting Nb/Pd multilayers  

Science Journals Connector (OSTI)

We have investigated the upper critical magnetic field Hc2, the critical current density Jc, and the pinning force Fp in sputtered Nb/Pd multilayers, varying the temperatures T, the Pd thicknesses dPd and the magnetic field H orientation (parallel and perpendicular to the plane of the sample). In perpendicular fields, the vortex dynamics was strongly influenced by grain-boundary pinning. In parallel fields, a peak was observed in the Jc(H) curves for samples with Pd thicknesses dPd>100 Å. After comparing the experimental results with the existing theories, we have related the presence of this peak effect to the matching of vortex kinks with the layered artificial structure.

C. Coccorese; C. Attanasio; L. V. Mercaldo; M. Salvato; L. Maritato; J. M. Slaughter; C. M. Falco; S. L. Prischepa; B. I. Ivlev

1998-04-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

On the dynamics of magnetic fluids in magnetic resonance imaging  

E-Print Network (OSTI)

The hydrodynamics of magnetic fluids, often termed ferrofluids, has been an active area of research since the mid 1960s. However, it is only in the past twenty years that these fluids have begun to be used in magnetic ...

Cantillon-Murphy, Pádraig J

2008-01-01T23:59:59.000Z

62

Studying Nanoscale Magnetism and its Dynamics with Soft X-ray Microscopy  

E-Print Network (OSTI)

and H.C. Siegmann, „Magnetism”, Springer (2006) P. Grünberg,HERE) magnetism and its dynamics withreasons [1]. Research of magnetism in low dimensions has led

Fischer, Peter

2008-01-01T23:59:59.000Z

63

Magnetic Soret effect: Application of the ferrofluid dynamics theory  

E-Print Network (OSTI)

The ferrofluid dynamics theory is applied to thermodiffusive problems in magnetic fluids in the presence of magnetic fields. The analytical form for the magnetic part of the chemical potential and the most general expression of the mass flux are given. By employing these results to experiments, global Soret coefficients in agreement with measurements are determined. Also an estimate for a hitherto unknown transport coefficient is made.

Adrian Lange

2004-11-11T23:59:59.000Z

64

Amplitude distribution of magnetoelastic waves propagating in a vortex field in a superconducting layer  

Science Journals Connector (OSTI)

Magnetic field enters the type ? II superconducting body along a discrete arrangement of magnetic vortex lines. In the dynamic case when the magnetic field vary in time around each such a line a supercurrent flows. So the vorticesinteract one to another with the help of the Lorentz force forming this way a new mechanical field of elastic properties. Moreover those lines arrange themselves in a triangular or quadratic lattice. Such a set is observed if the intensity of the applied to the materialmagnetic field is close to its lower limiting value. The paper aims at investigating amplitude distributions of magnetoelastic waves propagating solely in the vortex field of the superconducting layer. Our attention have been focused on the applied magnetic field intensity influence on those amplitudes for various wave frequencies.

Bogdan T. Maruszewski; Andrzej Drzewiecki; Roman Starosta

2008-01-01T23:59:59.000Z

65

RG analysis of magnetic catalysis in dynamical symmetry breaking  

SciTech Connect

We perform the renormalization group analysis on the dynamical symmetry breaking under strong external magnetic field, studied recently by Gusynin, Miransky and Shovkovy. We find that any attractive four-Fermi interaction becomes strong in the low energy, thus leading to dynamical symmetry breaking. When the four-Fermi interaction is absent, the {beta}-function for the electromagnetic coupling vanishes in the leading order in 1/N. By solving the Schwinger-Dyson equation for the fermion propagator, we show that in 1/N expansion, for any electromagnetic coupling, dynamical symmetry breaking occurs due to the presence of Landau energy gap by the external magnetic field. 5 refs.

Hong, Deog Ki [Pusan National Univ., (Korea). Dept. of Physics]|[Florida Univ., Gainesville, FL (United States); Kim, Youngman [Hanyang Univ., Seoul (Korea). Dept. of Physics

1996-05-01T23:59:59.000Z

66

On the Dynamics of Magnetic Fluids in Magnetic Resonance Padraig J. Cantillon-Murphy  

E-Print Network (OSTI)

On the Dynamics of Magnetic Fluids in Magnetic Resonance Imaging by Padraig J. Cantillon-Murphy Submitted to the Department of Electrical Engineering and Computer Science in partial fulfillment of Electric'algngineering and Computer Science May 22nd, 2008. Certified

67

Observation of the growth of a magnetic vortex in the transition layer of a mildly relativistic oblique plasma shock  

E-Print Network (OSTI)

A 2D particle simulation models the collision of two electron-ion plasma clouds along a quasi-parallel magnetic field. The collision speed is 0.9c and the density ratio 10. A current sheet forms at the front of the dense cloud, in which the electrons and the magnetic field reach energy equipartition with the ions. A structure composed of a solenoidal and a toroidal magnetic field grows in this sheet. It resembles that in the cross-section of the torus of a force-free spheromak, which may provide the coherent magnetic fields in gamma-ray burst (GRB) jets needed for their prompt emissions.

Murphy, G C; Drury, L O'C

2010-01-01T23:59:59.000Z

68

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.

69

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.

70

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.

71

Particle resuspension by an impacting vortex ring  

Science Journals Connector (OSTI)

Coherent vortex structures play a significant and important role in the dynamics of many commonly occurring natural flows, for example turbulent boundary layers and channel flows. One particularly important fe...

Rick J. Munro; Stuart B. Dalziel

2003-01-01T23:59:59.000Z

72

Magnetization dynamics of cobalt grown on graphene  

SciTech Connect

Ferromagnetic resonance (FMR) spin pumping is a rapidly growing field which has demonstrated promising results in a variety of material systems. This technique utilizes the resonant precession of magnetization in a ferromagnet to inject spin into an adjacent non-magnetic material. Spin pumping into graphene is attractive on account of its exceptional spin transport properties. This article reports on FMR characterization of cobalt grown on chemical vapor deposition graphene and examines the validity of linewidth broadening as an indicator of spin pumping. In comparison to cobalt samples without graphene, direct contact cobalt-on-graphene exhibits increased FMR linewidth—an often used signature of spin pumping. Similar results are obtained in Co/MgO/graphene structures, where a 1?nm MgO layer acts as a tunnel barrier. However, magnetometry, magnetic force microscopy, and Kerr microscopy measurements demonstrate increased magnetic disorder in cobalt grown on graphene, perhaps due to changes in the growth process and an increase in defects. This magnetic disorder may account for the observed linewidth enhancement due to effects such as two-magnon scattering or mosaicity. As such, it is not possible to conclude successful spin injection into graphene from FMR linewidth measurements alone.

Berger, A. J.; White, S. P.; Adur, R.; Pu, Y.; Hammel, P. C., E-mail: hammel@physics.osu.edu [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States); Amamou, W. [Department of Physics and Astronomy, University of California, Riverside, California 92521 (United States); Kawakami, R. K. [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Physics and Astronomy, University of California, Riverside, California 92521 (United States)

2014-05-07T23:59:59.000Z

73

Dynamical constraints from field line topology in magnetic flux tubes  

E-Print Network (OSTI)

A topological constraint on the dynamics of a magnetic field in a flux tube arises from the fixed point indices of its field line mapping. This can explain unexpected behaviour in recent resistive-magnetohydrodynamic simulations of magnetic relaxation. Here we present the theory for a general periodic flux tube, representing, for example, a toroidal confinement device or a solar coronal loop. We show how an ideal dynamics on the side boundary of the tube implies that the sum of indices over all interior fixed points is invariant. This constraint applies to any continuous evolution inside the tube, which may be turbulent and/or dissipative. We also consider the analogous invariants obtained from periodic points (fixed points of the iterated mapping). Although there is a countably infinite family of invariants, we show that they lead to at most two independent dynamical constraints. The second constraint applies only in certain magnetic configurations. Several examples illustrate the theory.

A. R. Yeates; G. Hornig

2011-03-11T23:59:59.000Z

74

Tunable dynamic response of magnetic gels: impact of structural properties and magnetic fields  

E-Print Network (OSTI)

Ferrogels and magnetic elastomers feature mechanical properties that can be reversibly tuned from outside through magnetic fields. Here we concentrate on the question how their dynamic response can be adjusted. The influence of three factors on the dynamic behavior is demonstrated using appropriate minimal models: first, the orientational memory imprinted into one class of the materials during their synthesis; second, the structural arrangement of the magnetic particles in the materials; and third, the strength of an external magnetic field. To illustrate the latter point, structural data are extracted from a real experimental sample and analyzed. Understanding how internal structural properties and external influences impact the dominant dynamical properties helps to design materials that optimize the requested behavior.

Mitsusuke Tarama; Peet Cremer; Dmitry Y. Borin; Stefan Odenbach; Hartmut Löwen; Andreas M. Menzel

2014-06-26T23:59:59.000Z

75

Dynamics of Whistler Spheromaks in Magnetized Plasmas  

Science Journals Connector (OSTI)

Recent laboratory experiments [Stenzel et al., Phys. Rev. Lett. 96, 095004 (2006)] have demonstrated interesting phenomena of propagating nonlinear whistler structures (spheromaks) and stationary field-reversed configurations, whose magnetic fields exceed the ambient magnetic field strength. Our objective here is to present simulation studies for these nonlinear whistler structures based on the three-dimensional nonlinear electron magnetohydrodynamic equations. The robustness and longevity of the propagating whistler spheromaks found in the experiments are confirmed numerically. Varying the toroidal field of the spheromak in the initial conditions, we find that the polarity and the amplitude of the toroidal field determine the propagation direction and speed of the spheromak. Our simulation results are in excellent agreement with those observed in the laboratory experiments.

B. Eliasson and P. K. Shukla

2007-11-15T23:59:59.000Z

76

Polarization of the vacuum of a quantized scalar field by an impenetrable magnetic vortex of finite thickness  

E-Print Network (OSTI)

We consider the effect of the magnetic field background in the form of a tube of the finite transverse size on the vacuum of the quantized charged massive scalar field which is subject to the Dirichlet boundary condition at the tube. It is shown that, if the Compton wavelength associated with the scalar field exceeds considerably the transverse size of the tube, then the vacuum energy which is finite and periodic in the value of the magnetic flux enclosed in the tube is induced on a plane transverse to the tube. Some consequences for generic features of the vacuum polarization in the cosmic-string background are discussed.

V. M. Gorkavenko; Yu. A. Sitenko; O. B. Stepanov

2009-11-15T23:59:59.000Z

77

Magnetic flux emergence and associated dynamic phenomena in the Sun  

Science Journals Connector (OSTI)

...and H. Zirin 1985 Magnetic shear. I. Hale region 16918. Astrophys. J. 288, 363-372...The dynamical state of the interstellar gas and field. Astrophys. J. 145, 811...and application to the origin of X-ray gas in the galactic halo. Astrophys. J. 582...

2012-01-01T23:59:59.000Z

78

Journal of Magnetism and Magnetic Materials 290291 (2005) 836838 Dynamic response limits of an elastic magnet  

E-Print Network (OSTI)

on the elastomagnetic coupling but also on the interaction among the microparticles magnetic moments depending as for possible applications [1,2]. When the magnetic particles are permanently magnetized and the matrix material. Bar shaped samples have been produced with the permanent magnetic moments preferentially oriented

Franzese, Giancarlo

79

Vortex lines in films: Fields and interactions  

Science Journals Connector (OSTI)

General expressions are given for the magnetic field and energy of arbitrary arrangements of straight and curved vortices in an anisotropic superconductor film of finite thickness within anisotropic London theory. As examples we consider the magnetic field and interaction of straight perpendicular vortex lines in films of finite thickness.

Gilson Carneiro and Ernst Helmut Brandt

2000-03-01T23:59:59.000Z

80

Knots and dynamics tienne Ghys  

E-Print Network (OSTI)

was the starting point of the (now forgotten) theory of "vortex atoms", trying to explain elementary "atoms-hydrodynamics: the dynamics of electrically conducting fluids (like a plasma). If one assumes that the fluid is perfect and has no resistance (ideal MHD), the magnetic (divergence free) vector field is merely tran

Ghys, Ã?tienne

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

Ultrafast Magnetism Dynamics Measure Using Tabletop Ultrafast EUV Sources  

SciTech Connect

In our work to date, we made two significant advances. First we demonstrated element-selective demagnetization dynamics for the first time, with a record time resolution for x-ray probing of 55 fs. Second, in new work, we were able to probe the timescale of the exchange interaction in magnetic materials, also for the first time. Our measurements were made using the transverse magneto-optic Kerr effect (T-MOKE) geometry, since the reflectivity of a magnetic material changes with the direction of the magnetization vector of a surface. In our experiment, we periodically reversed the magnetization direction of a grating structure made of Permalloy (Ni80Fe20) using an external magnetic field. To achieve maximum contrast, we used HHG light spanning the M-shell (3p) absorption edges of Fe and Ni. Our characterization of the static magnetization of a Permalloy sample shows high magnetic asymmetry at photon energies just above and below the absorption edges at 55 eV and 65 eV, respectively. This result is in excellent agreement with measurements done on the same using a synchrotron source.

Silva, Thomas J. [NIST] [NIST; Murnane, Margaret [University of Colorado] [University of Colorado

2013-08-21T23:59:59.000Z

82

PHYSICAL REVIEW B 89, 144404 (2014) Subpicosecond magnetization dynamics in TbCo alloys  

E-Print Network (OSTI)

for magneto-optical recording and the permanent magnet industry. The magnetization of the alloy results from, the magnetizations of the two sublattices are exchange coupled antiferromagnetically and the alloys are called magnetization dynamics of the two antiparallel coupled magnetic sublattices (i.e., Gd and FeCo) after laser

Aeschlimann, Martin

83

Vortex precession frequency and its amplitude-dependent shift in cylindrical nanomagnets  

SciTech Connect

Frequency of free magnetic vortex precession in circular soft ferromagnetic nano-cylinders (magnetic dots) of various sizes is an important parameter, used in design of spintronic devices (such as spin-torque microwave nano-oscillators) and characterization of magnetic nanostructures. Here, using a recently developed collective-variable approach to non-linear dynamics of magnetic textures in planar nano-magnets, this frequency and its amplitude-dependent shift are computed analytically and plotted for the full range of cylinder geometries. The frequency shift is positive in large planar dots, but becomes negative in smaller and more elongated ones. At certain dot dimensions, a zero frequency shift is realized, which can be important for enhancing frequency stability of magnetic nano-oscillators.

Metlov, Konstantin L., E-mail: metlov@fti.dn.ua [Donetsk Institute for Physics and Technology NAS, Donetsk 83114 (Ukraine)

2013-12-14T23:59:59.000Z

84

Vortex reconnections in atomic condensates at finite temperature A. J. Allen1  

E-Print Network (OSTI)

, reconnections of stream lines, vortex lines and magnetic flux tubes change the topology of the flowVortex reconnections in atomic condensates at finite temperature A. J. Allen1 , S. Zuccher2 , M (Dated: May 28, 2014) The study of vortex reconnections is an essential ingredient of understanding

Zuccher, Simone

85

Magnetic field topology and field lines structure in the Dynamic Ergodic Divertor of TEXTOR-94  

Science Journals Connector (OSTI)

An analytical model of the magnetic field perturbations and the mapping technique to study field line dynamics in an ergodic divertor tokamak are developed. The analytical formulas for the vacuum magnetic field p...

S. S. Abdullaev; K. H. Finken; A. Kaleck…

1998-01-01T23:59:59.000Z

86

Dynamic control of spin states in interacting magnetic elements  

DOE Patents (OSTI)

A method for the control of the magnetic states of interacting magnetic elements comprising providing a magnetic structure with a plurality of interacting magnetic elements. The magnetic structure comprises a plurality of magnetic states based on the state of each interacting magnetic element. The desired magnetic state of the magnetic structure is determined. The active resonance frequency and amplitude curve of the desired magnetic state is determined. Each magnetic element of the magnetic structure is then subjected to an alternating magnetic field or electrical current having a frequency and amplitude below the active resonance frequency and amplitude curve of said desired magnetic state and above the active resonance frequency and amplitude curve of the current state of the magnetic structure until the magnetic state of the magnetic structure is at the desired magnetic state.

Jain, Shikha; Novosad, Valentyn

2014-10-07T23:59:59.000Z

87

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

88

Creation and pinning of vortex-antivortex pairs  

E-Print Network (OSTI)

Computer modeling is reported about the creation and pinning of a magnetic vortex-antivortex (V-AV) pair in a superconducting thin film, due to the magnetic field of a vertical magnetic dipole above the film, and two antidot pins inside the film...

Kim, Sangbum; Hu, Chia-Ren; Andrews, Malcolm J.

2006-01-01T23:59:59.000Z

89

Dynamic magnetic susceptibility of systems with long-range magnetic order  

SciTech Connect

The utility of the TDR as an instrument in the study of magnetically ordered materials has been expanded beyond the simple demonstration purposes. Results of static applied magnetic field dependent measurements of the dynamic magnetic susceptibility, ?, of various ferromagnetic (FM) and antiferromagnetic (AFM) materials showing a range of transition temperatures (1-800 K) are presented. Data was collected primarily with a tunnel diode resonator (TDR) at different radio-frequencies ({approx}10-30 MHz). In the vicinity of TC local moment ferromagnets show a very sharp, narrow peak in ? which is suppressed in amplitude and shifted to higher temperatures as the static bias field is increased. Unexpectedly, critical scaling analysis fails for these data. It is seen that these data are frequency dependent, however there is no simple method whereby measurement frequency can be changed in a controllable fashion. In contrast, itinerant ferromagnets show a broad maximum in ? well below TC which is suppressed and shifts to lower temperatures as the dc bias field is increased. The data on itinerant ferromagnets is fitted to a semi-phenomenological model that suggests the sample response is dominated by the uncompensated minority spins in the conduction band. Concluding remarks suggest possible scenarios to achieve frequency resolved data using the TDR as well as other fields in which the apparatus may be exploited.

Vannette, Matthew Dano

2009-05-15T23:59:59.000Z

90

Vortex and gap generation in gauge models of graphene  

E-Print Network (OSTI)

Effective quantum field theoretical continuum models for graphene are investigated. The models include a complex scalar field and a vector gauge field. Different gauge theories are considered and their gap patterns for the scalar, vector, and fermion excitations are investigated. Different gauge groups lead to different relations between the gaps, which can be used to experimentally distinguish the gauge theories. In this class of models the fermionic gap is a dynamic quantity. The finite-energy vortex solutions of the gauge models have the flux of the "magnetic field" quantized, making the Bohm-Aharonov effect active even when external electromagnetic fields are absent. The flux comes proportional to the scalar field angular momentum quantum number. The zero modes of the Dirac equation show that the gauge models considered here are compatible with fractionalization.

O. Oliveira; C. E. Cordeiro; A. Delfino; W. de Paula; T. Frederico

2010-12-21T23:59:59.000Z

91

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

92

Nonlinear dynamics of feedback modulated magnetic islands in toroidal plasmas  

E-Print Network (OSTI)

'' tear and reconnect magnetic field lines to produce helical chains of magnetic islands inside the plasma one side of an island chain to the other by flowing along magnetic field lines, which is a relatively plasmas, give rise to the ergodization of the magnetic field, and the conse- quent destruction of ordered

Fitzpatrick, Richard

93

Magnetic Field Control of the Quantum Chaotic Dynamics of Hydrogen Analogues in an Anisotropic Crystal Field  

E-Print Network (OSTI)

We report magnetic field control of the quantum chaotic dynamics of hydrogen analogues in an anisotropic solid state environment. The chaoticity of the system dynamics was quantified by means of energy level statistics. We analyzed the magnetic field dependence of the statistical distribution of the impurity energy levels and found a smooth transition between the Poisson limit and the Wigner limit, i.e. transition between regular Poisson and fully chaotic Wigner dynamics. Effect of the crystal field anisotropy on the quantum chaotic dynamics, which manifests itself in characteristic transitions between regularity and chaos for different field orientations, was demonstrated.

Weihang Zhou; Zhanghai Chen; Bo Zhang; C. H. Yu; Wei Lu; S. C. Shen

2010-03-09T23:59:59.000Z

94

Vortex Characterization for Engineering Applications  

SciTech Connect

Realistic engineering simulation data often have features that are not optimally resolved due to practical limitations on mesh resolution. To be useful to application engineers, vortex characterization techniques must be sufficiently robust to handle realistic data with complex vortex topologies. In this paper, we present enhancements to the vortex topology identification component of an existing vortex characterization algorithm. The modified techniques are demonstrated by application to three realistic data sets that illustrate the strengths and weaknesses of our approach.

Jankun-Kelly, M; Thompson, D S; Jiang, M; Shannahan, B; Machiraju, R

2008-01-30T23:59:59.000Z

95

Formation and dynamics of easy orientation axis in magnetic field on PVCN-F surface  

E-Print Network (OSTI)

of Sciences of Ukraine, 46 Nauki Str., 03-039 Kyiv, Ukraine 2Condensed Phase Dynamics Group, University University, 6 Glushkova Str., 03-680, Kyiv, Ukraine We describe the experiments on a magnetically

Reznikov, Yuri

96

Dynamic Transitions in Pure Ising Magnets under Pulsed and Oscillating Fields  

E-Print Network (OSTI)

Dynamic Transitions in Pure Ising Magnets under Pulsed and Oscillating Fields Bikas K. Chakrabarti. Abstract Response of pure Ising systems to time-dependent external magnetic #28;elds, like pulsed case is that of an Ising ferromagnet below its static critical temperature, when it is perturbed

Usadel, K. D.

97

Dynamics of chaotic magnetic lines and noble ITB's in the Tokamap J. H. Misguich and Fusion BFR Working Group (*)  

E-Print Network (OSTI)

Dynamics of chaotic magnetic lines and noble ITB's in the Tokamap J. H. Misguich and Fusion BFR and study the dynamics of magnetic lines in a situation of " incomplete chaos". Several previous studies have used Hamiltonian mapping to represent magnetic lines. Here we use the Hamiltonian twist map

98

Nucleation-controlled vortex entry in a square-columnar Josephson-junction array  

SciTech Connect

The initial magnetization curve of square-columnar Josephson-junction arrays is calculated from fundamental laws. It is found that the first vortex entry is controlled by vortex nucleation rather than surface depinning and it occurs at a field greater than that predicted by the traditional surface-barrier theory. {copyright} {ital 1997} {ital The American Physical Society}

Chen, D.; Moreno, J.J.; Hernando, A. [Instituto de Magnetismo Aplicado, RENFE-UCM-CSIC, 28230 Las Rozas, Madrid (Spain)] [Instituto de Magnetismo Aplicado, RENFE-UCM-CSIC, 28230 Las Rozas, Madrid (Spain)

1997-08-01T23:59:59.000Z

99

The Ising Model on a Dynamically Triangulated Disk with a Boundary Magnetic Field  

E-Print Network (OSTI)

We use Monte Carlo simulations to study a dynamically triangulated disk with Ising spins on the vertices and a boundary magnetic field. For the case of zero magnetic field we show that the model possesses three phases. For one of these the boundary length grows linearly with disk area, while the other two phases are characterized by a boundary whose size is on the order of the cut-off. A line of continuous magnetic transitions separates the two small boundary phases. We determine the critical exponents of the continuous magnetic phase transition and relate them to predictions from continuum 2-d quantum gravity. This line of continuous transitions appears to terminate on a line of discontinuous phase transitions dividing the small boundary phases from the large boundary phase. We examine the scaling of bulk magnetization and boundary magnetization as a function of boundary magnetic field in the vicinity of this tricritical point.

Scott McGuire; Simon Catterall; Mark Bowick; Simeon Warner

2001-05-02T23:59:59.000Z

100

Magnetic and electric contributions to the energy loss in a dynamical QCD medium  

E-Print Network (OSTI)

The computation of radiative energy loss in a finite size QCD medium with dynamical constituents is a key ingredient for obtaining reliable predictions for jet quenching in ultra-relativistic heavy ion collisions. It was previously shown that energy loss in dynamical QCD medium is significantly higher compared to static QCD medium. To understand this difference, we here analyze magnetic and electric contributions to energy loss in dynamical QCD medium. We find that the significantly higher energy loss in the dynamical case is entirely due to appearance of magnetic contribution in the dynamical medium. While for asymptotically high energies, the energy loss in static and dynamical medium approach the same value, we find that the physical origin of the energy loss in these two cases is different.

Magdalena Djordjevic

2011-05-21T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

Investigation of relaxation phenomena in high-temperature superconductors HoBa2Cu3O7-d at the action of pulsed magnetic fields  

E-Print Network (OSTI)

It is used the mechanical method of Abrikosov vortex stimulated dynamics investigation in superconductors. With its help it was studied relaxation phenomena in vortex matter of high-temperature superconductors. It established that pulsed magnetic fields change the course of relaxation processes taking place in vortex matter. The study of the influence of magnetic pulses differing by their durations and amplitudes on vortex system of isotropic high-temperature superconductors system HoBa2Cu3O7-d showed the presence of threshold phenomena. The small duration pulses does not change the course of relaxation processes taking place in vortex matter. When the duration of pulses exceeds some critical value (threshold), then their influence change the course of relaxation process which is revealed by stepwise change of relaxing mechanical moment . These investigations showed that the time for formatting of Abrikosov vortex lattice in HoBa2Cu3O7-d is of the order of 20 microsec. which on the order of value exceeds the time necessary for formation of a single vortex observed in type II superconductors.

J. G. Chigvinadze; J. V. Acrivos; S. M. Ashimov; A. A. Iashvili; T. V. Machaidze; Th. Wolf

2007-04-03T23:59:59.000Z

102

Magnetic soft x-ray microscopy-imaging fast spin dynamics in magnetic nanostructures  

E-Print Network (OSTI)

fundamental time scale in magnetism is given by the time required to transfer energy and momentum from the electronic

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

2007-01-01T23:59:59.000Z

103

SU(2s+1) symmetry and nonlinear dynamic equations of spin s magnets  

E-Print Network (OSTI)

The article is devoted to the description of dynamics of magnets with arbitrary spin on the basis of the Hamiltonian formalism. The relationship between the magnetic ordering and Poisson bracket subalgebras of the magnetic degrees of freedom for spin s=1/2; 1; 3/2 has been established. We have been obtained non-linear dynamic equations without damping for normal and degenerate non-equilibrium states of high-spin magnets with the properties of the SO(3), SU(4), SU(2)$\\times$SU(2), SU(3), SO(4), SO(5) symmetry of exchange interaction. The connection between models of the magnetic exchange energy and the Casimir invariants has been discussed.

M. Y. Kovalevsky; A. V. Glushchenko

2013-12-20T23:59:59.000Z

104

Axisymmetric-coherent-vortex states in current-driven Josephson-junction arrays  

SciTech Connect

We present results from an extensive analysis of the dynamic response of Josephson-junction arrays driven by external currents of the form [ital I]=[ital I][sub dc]+[ital I][sub ac]sin(2[pi][nu][ital t]). The dynamics is given by the resistively shunted Josephson-junction model with Johnson noise. We find a stationary [ital axisymmetric][minus][ital coherent][minus][ital vortex] [ital state] (ACVS) away from equilibrium and above a minimum lattice size ([similar to]20[times]20) whenever the initial state has at least one antivortex and a vortex. The ACVS is characterized by tilted rows of oscillating positive and negative vortices, produced by the combined effect of the driving current plus the collective coupling of the nonlinear Josephson oscillators. The ACVS is manifested in the current-voltage characteristics as giant half-integer Shapiro steps, leading to period-two resonances in the spectral function. The stability and properties of the ACVS are studied as a function of frequency, temperature, disorder, edge magnetic fields, and lattice sizes. It is found that the ACVS is a very robust two-dimensional dynamical state that is produced under very diverse circumstances. A connection between the ACVS and half-integer steps seen in proximity effect arrays in zero field is also discussed.

Dominguez, D.; Jose, J.V. (Physics Department, Northeastern University, Boston, Massachusetts 02115 (United States))

1993-11-01T23:59:59.000Z

105

Vortex motion in Josephson-junction arrays near f=0 and f=1/2  

Science Journals Connector (OSTI)

We study vortex motion in two-dimensional Josephson arrays at magnetic fields near zero and one-half flux quanta per plaquette (f=0 and f=1/2). The array is modeled as a network of resistively and capacitively shunted Josephson junctions at temperature T=0. Calculations are carried out over a range of the McCumber-Stewart junction damping parameter ?. Near both f=0 and f=1/2, the I-V characteristics exhibit two critical currents, Ic1(f) and Ic2(f), representing the critical current for depinning a single vortex, and for depinning the entire ground-state phase configuration. Near f=0, single vortex motion just above Ic1(0) leads to Josephson-like voltage oscillations. The motion of the vortex is seemingly overdamped (i.e., nonhysteretic) even when the individual junction parameters are highly underdamped, in agreement with experiments. At sufficiently large ?, and sufficiently high vortex velocity, the vortex breaks up into a row of resistively switched junctions perpendicular to the current. Near f=1/2, the vortex potential, and corresponding vortex trajectories, are more complicated than near f=0. Nevertheless, the vortex is still ‘‘overdamped’’ even when the individual junctions are highly underdamped, and there is still row-switching behavior at large values of ?. A high-energy vortex in a very underdamped array tends to generate resistively switched rows rather than to move ballistically. Some possible explanations for this behavior are discussed.

Wenbin Yu; K. H. Lee; D. Stroud

1993-03-01T23:59:59.000Z

106

Dynamic Control of Spin Sates in Interacting Magnetic Elements...  

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

Contact GRANT About This Technology Technology Marketing Summary U.S. patent 8,885,871 issued on an invention from Argonne National Laboratory (ANL) entitled, "Dynamic...

107

DYNAMICAL FRICTION IN A GASEOUS MEDIUM WITH A LARGE-SCALE MAGNETIC FIELD  

SciTech Connect

The dynamical friction force experienced by a massive gravitating body moving through a gaseous medium is modified by sufficiently strong large-scale magnetic fields. Using linear perturbation theory, we calculate the structure of the wake generated by, and the gravitational drag force on, a body traveling in a straight-line trajectory in a uniformly magnetized medium. The functional form of the drag force as a function of the Mach number ({identical_to} V{sub 0}/c{sub s} , where V{sub 0} is the velocity of the body and c{sub s} is the sound speed) depends on the strength of the magnetic field and on the angle between the velocity of the perturber and the direction of the magnetic field. In particular, the peak value of the drag force is not near Mach number {approx}1 for a perturber moving in a sufficiently magnetized medium. As a rule of thumb, we may state that for supersonic motion, magnetic fields act to suppress dynamical friction; for subsonic motion, they tend to enhance dynamical friction. For perturbers moving along the magnetic field lines, the drag force at some subsonic Mach numbers may be stronger than at supersonic velocities. We also mention the relevance of our findings to black hole coalescence in galactic nuclei.

Sanchez-Salcedo, F. J., E-mail: jsanchez@astroscu.unam.mx [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, 04510 Mexico City (Mexico)

2012-02-01T23:59:59.000Z

108

Low-field vortex matter in YBa2Cu3O7 : An atomic beam magnetic-resonance study Harald Hauglin  

E-Print Network (OSTI)

the rate that rf magnetic-resonance hyperfine tran- sitions are excited in atoms as they pass over Department of Physics, University of Oslo, N-0316 Oslo, Norway Nathan G. Woodard, Samuel Dapore-Schwartz, and Gregory P. Lafyatis Department of Physics, The Ohio State University, Columbus, Ohio 43210-1106 Received

Johansen, Tom Henning

109

Electronic and Magnetization Dynamics of Cobalt Substituted Iron Oxide Nanocrystals  

E-Print Network (OSTI)

4.3 Electronic Structures of Inverse Spinel Fe 3 O 4 Nanocrystals ... 62 4.4 Electronic Dynamics of Photoexcited Colloidal Fe 3 O 4 Nanocrystals... 4.3 Electronic Structures of Inverse Spinel Fe 3 O 4 Nanocrystals ... 62 4.4 Electronic Dynamics of Photoexcited Colloidal Fe 3 O 4 Nanocrystals...

Chen, Tai-Yen

2011-02-22T23:59:59.000Z

110

Cylindrical Ising nanowire in an oscillating magnetic field and dynamic compensation temperature  

Science Journals Connector (OSTI)

Abstract The nonequilibrium magnetic properties of a spin-1/2 cylindrical Ising nanowire system with core/shell in an oscillating magnetic field are studied by using a mean-field approach based on the Glauber-type stochastic dynamics (DMFT). We employ the Glauber-type stochastic dynamics to construct set of the coupled mean-field dynamic equations. First, we study the temperature dependence of the dynamic order parameters to characterize the nature of the phase transitions and to obtain the dynamic phase transition points. Then, we investigate the temperature dependence of the total magnetization to find the dynamic compensation points as well as to determine the type of behavior. The phase diagrams in which contain the paramagnetic, ferromagnetic, ferrimagnetic, partially nonmagnetic, surface fundamental phases and tree mixed phases as well as reentrant behavior are presented in the reduced magnetic field amplitude and reduced temperature plane. According to values of Hamiltonian parameters, the compensation temperatures, or the N-, Q-, P-, R-, S-type behaviors.

Ersin Kantar; Mehmet Erta?

2014-01-01T23:59:59.000Z

111

The design of a test rig for the identification of dynamic coefficients of a high temperature magnetic bearing  

E-Print Network (OSTI)

This thesis is a report on the research and Micrographics. development to design a test rig for the identification of the dynamic coefficients of a radial magnetic bearing. The test rig development is intended for dynamic coefficient observation...

Rahtika, I Putu Gede Sopan

1998-01-01T23:59:59.000Z

112

Application of Landau-Lifshitz-Bloch dynamics to grain switching in heat-assisted magnetic recording  

Science Journals Connector (OSTI)

Magnetization dynamics in heat-assisted magnetic recording (HAMR) involves magnetization collapse and re-formation under rapid local temperature excursion in a temporally varying applied magnetic field with temperature likely moving above and below the medium Curie point on nanosecond timescales. Traditional micromagnetic simulation of the writing process in magnetic data storage has been restricted to isothermal processes in which macrospin magnetization dynamics are handled with the well-established Landau-Lifshitz-Gilbert (LLG) algorithm or close variants. Classical LLG treats the magnitude of material magnetization M as fixed (at zero Kelvin) so initial attempts at micromagnetic analysis of HAMR have typically dealt with the effects of temperature variation in HAMR in a somewhat ad hoc manner (e.g. insertion of M(T) A(T) K(T)) and have not been rigorous. A much improved treatment of this problem substitutes the Landau-Lifshitz-Bloch (LLB) algorithm in which thermally driven magnetization variation is treated more correctly in an extended semi-classical Landau-Lifshitz framework Here we study single-grain switching with this method under application of time-varying temperature and H-field. For a typical system setup we map phase diagrams of grain switching probability over the space of important HAMR parameters such as peak temperature elevation applied H-field strength and the synchronization of temperature and field.

Terry W. McDaniel

2012-01-01T23:59:59.000Z

113

Non-equilibrium coherent vortex states and subharmonic giant Shapiro steps in Josephson junction arrays  

E-Print Network (OSTI)

This is a review of recent work on the dynamic response of Josephson junction arrays driven by dc and ac currents. The arrays are modeled by the resistively shunted Josephson junction model, appropriate for proximity effect junctions, including self-induced magnetic fields as well as disorder. The relevance of the self-induced fields is measured as a function of a parameter $\\kappa=\\lambda_L/a$, with $\\lambda_L$ the London penetration depth of the arrays, and $a$ the lattice spacing. The transition from Type II ($\\kappa>1$) to Type I ($\\kappa <1$) behavior is studied in detail. We compare the results for models with self, self+nearest-neighbor, and full inductance matrices. In the $\\kappa=\\infty$ limit, we find that when the initial state has at least one vortex-antivortex pair, after a characteristic transient time these vortices unbind and {\\it radiate} other vortices. These radiated vortices settle into a parity-broken, time-periodic, {\\em axisymmetric coherent vortex state} (ACVS), characterized by alternate rows of positive and negative vortices lying along a tilted axis. The ACVS produces subharmonic steps in the current voltage (IV) characteristics, typical of giant Shapiro steps. For finite $\\kappa$ we find that the IV's show subharmonic giant Shapiro steps, even at zero external magnetic field. We find that these subharmonic steps are produced by a whole family of coherent vortex oscillating patterns, with their structure changing as a function of $\\kappa$. In general, we find that these patterns are due to a break down of translational invariance produced, for example, by disorder or antisymmetric edge-fields. The zero field case results are in good qualitative agreement with experiments

Daniel Domínguez; Jorge V. José

1994-07-11T23:59:59.000Z

114

Liquid Vortex Shielding for Fusion Energy Applications  

SciTech Connect

Swirling liquid vortices can be used in fusion chambers to protect their first walls and critical elements from the harmful conditions resulting from fusion reactions. The beam tube structures in heavy ion fusion (HIF) must be shielded from high energy particles, such as neutrons, x-rays and vaporized coolant, that will cause damage. Here an annular wall jet, or vortex tube, is proposed for shielding and is generated by injecting liquid tangent to the inner surface of the tube both azimuthally and axially. Its effectiveness is closely related to the vortex tube flow properties. 3-D particle image velocimetry (PIV) is being conducted to precisely characterize its turbulent structure. The concept of annular vortex flow can be extended to a larger scale to serve as a liquid blanket for other inertial fusion and even magnetic fusion systems. For this purpose a periodic arrangement of injection and suction holes around the chamber circumference are used, generating the layer. Because it is important to match the index of refraction of the fluid with the tube material for optical measurement like PIV, a low viscosity mineral oil was identified and used that can also be employed to do scaled experiments of molten salts at high temperature.

Bardet, Philippe M. [University of California, Berkeley (United States); Supiot, Boris F. [University of California, Berkeley (United States); Peterson, Per F. [University of California, Berkeley (United States); Savas, Oemer [University of California, Berkeley (United States)

2005-05-15T23:59:59.000Z

115

Magnetic flux dynamics in a hexagonal network of superconducting islands  

E-Print Network (OSTI)

critical states, of inter- and intra-granular screening currents. The rate of flux penetration-based tapes. The magneto-optical observation showed a flux penetration/reversal process consisting of two Bean penetration into the grains. The grain magnetization was non- uniform and asymmetrical. Although grains stood

Johansen, Tom Henning

116

Electromagnetic Behavior of the Vortex Sponge  

Science Journals Connector (OSTI)

In an introductory paper the vortex sponge was shown to be governed in restricted cases by Maxwell's free-space equations. In the present paper analogs to electric and magnetic energies and Poynting's theorem are derived by simple mechanical considerations. Rotational stability suggested originally by MacCullagh as a fundamental property of a luminiferous ether turns out to be a quality of the medium as do the stresses introduced by Faraday and Maxwell to explain the mechanical actions of electric and magnetic fields. A rudimentary model for the electrostatic field is suggested on this basis. A conventional definition of charge and the laws of Coulomb and Biot complete Maxwell's equations for cases including charges and currents. A model of the magnetic field based on the bulk rotation and the Faraday-Maxwell stresses combined with the laws of Coulomb and Biot permits the inference of the Lorentz force. Although numerous gaps occur in the treatment it seems not unlikely that the vortex sponge has the qualities described by the electromagnetic field equations as well as the mechanical attributes required for a model of these fields.

Edward M. Kelly

1964-01-01T23:59:59.000Z

117

Dynamics of Runaway Electrons in the Magnetic Field of a Tokamak  

Science Journals Connector (OSTI)

An energy cap of runaway electrons is found experimentally by observing their bremsstrahlung spectra in the ASDEX tokamak. This observation is explained by analyzing the dynamics of runaway electrons, including acceleration in the toroidal electric field, deceleration due to synchrotron radiation losses, collisions with plasma particles, and a resonance between gyromotion and magnetic field ripple of the tokamak. For the dynamics of runaway electrons a Fokker-Planck equation in momentum space is developed.

B. Kurzan; K. -H. Steuer; G. Fussmann

1995-12-18T23:59:59.000Z

118

Symmetry Constraints on the Dynamics of Magnetically Confined Plasma  

SciTech Connect

In respect of their symmetry properties, toroidal magnetically confined plasmas have much in common with the Taylor-Couette flow. A symmetry-based analysis (equivalent bifurction theory) has proved very powerful in the analysis of the latter problem. This Letter discusses the applicability of the method to nuclear fusion experiments such as tokamaks and pinches. The likely behavior of the simplest models of rotationally symmetric tokamaks is described, and found to be potentially consistent with observation.

Arter, Wayne [EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom)

2009-05-15T23:59:59.000Z

119

Ising-like dynamics and frozen states in systems of ultrafine magnetic particles Stefanie Russ and Armin Bunde  

E-Print Network (OSTI)

Ising-like dynamics and frozen states in systems of ultrafine magnetic particles Stefanie Russ flips of the magnetic moments, as in Ising systems. Since the dipolar interaction favorizes- polar and anisotropy energy, the magnetic moments have a tendency to align in an Ising-like manner

von Oppen, Felix

120

Dynamical Feedback of Self-generated Magnetic Fields in Cosmic Rays Modified Shocks  

SciTech Connect

We present a semi-analytical kinetic calculation of the process of non-linear diffusive shock acceleration (NLDSA) which includes magnetic field amplification due to cosmic ray induced streaming instability, the dynamical reaction of the amplified magnetic field and the possible effects of turbulent heating. This kinetic calculation allows us to show that the net effect of the amplified magnetic field is to enhance the maximum momentum of accelerated particles while reducing the concavity of the spectra, with respect to the standard predictions of NLDSA. This is mainly due to the dynamical reaction of the amplified field on the shock, which smoothens the shock precursor. The total compression factors which are obtained for parameters typical of supernova remnants are R{sub tot} {approx} 7-10, in good agreement with the values inferred from observations. The strength of the magnetic field produced through excitation of streaming instability is found in good agreement with the values inferred for several remnants if the thickness of the X-ray rims are interpreted as due to severe synchrotron losses of high energy electrons. We also discuss the relative role of turbulent heating and magnetic dynamical reaction in smoothening the shock precursor.

Caprioli, D.; /Pisa, Scuola Normale Superiore; Blasi, P.; /Arcetri Observ. /Fermilab; Amato, E.; /Arcetri Observ.; Vietri, M.; /Pisa, Scuola Normale Superiore

2008-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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.
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121

Short-time dynamics of Fe{sub 2}/V{sub 13} magnetic superlattice models  

SciTech Connect

Critical relaxation from a low-temperature fully ordered state of Fe{sub 2}/V{sub 13} iron-vanadium magnetic superlattice models has been studied using the method of short-time dynamics. Systems with three variants of the ratio R of inter-to intralayer exchange coupling have been considered. Particles with N = 262144 spins have been simulated with periodic boundary conditions. Calculations have been performed using the standard Metropolis algorithm of the Monte Carlo method. The static critical exponents of magnetization and correlation radius, as well as the dynamic critical exponent, have been calculated for three R values. It is established that a small decrease in the exchange ratio (from R = 1.0 to 0.8) does not significantly influence the character of the short-time dynamics in the models studied. A further significant decrease in this ratio (to R = 0.01), for which a transition from three-dimensional to quasi-two-dimensional magnetism is possible, leads to significant changes in the dynamic behavior of iron-vanadium magnetic superlattice models.

Murtazaev, A. K.; Mutailamov, V. A., E-mail: vadim.mut@mail.ru [Russian Academy of Sciences, Amirkhanov Institute of Physics, Daghestan Scientific Center (Russian Federation)

2013-04-15T23:59:59.000Z

122

WAVE-VORTEX INTERACTIONS IN THE ATMOSPHERE, AND CLIMATE  

E-Print Network (OSTI)

parcel dynamics, linear modes, balan- ced models, gravity waves, weather and climate prediction Introduction Numerical weather and climate prediction is complicated because only the flow scales larger thanWAVE-VORTEX INTERACTIONS IN THE ATMOSPHERE, AND CLIMATE PREDICTION Onno Bokhove Numerical Analysis

Vellekoop, Michel

123

Direct measurements of ion dynamics in collisional magnetic presheaths  

SciTech Connect

Ion velocities and temperatures are measured in the presheath of a grounded plate downstream from an argon helicon plasma source using laser-induced fluorescence (P{sub rf}?450?750?W, T{sub e}=2.5?5?eV, T{sub i}=0.1?0.6?eV, n{sub 0}?1×10{sup 12}cm{sup ?3},?p{sub n}=1?6.5?mTorr, ?=0.3?2?cm, ?{sub i}??0.5?cm). The plate is held 16°?60° relative to the 1?kG background axial magnetic field. The velocity profiles are compared to a 1D fluid model similar to those presented by Riemann [Phys. Plasmas 1, 552 (1994)] and Ahedo [Phys. Plasmas 4, 4419 (1997)] for the 1 mTorr dataset and are shown to agree well. The model is sensitive to parameters such as collision and ionization frequencies and simplified models, such one presented by Chodura [Phys. Fluids 25, 1628 (1982)], are shown to be inaccurate. E{sup ?}×B{sup ?} flows as large as 40% of c{sub s} at the sheath edge are inferred. Definitions for the term “magnetic presheath” and implications for ion flow to tokamak divertors and Hall thruster walls are discussed.

Siddiqui, M. Umair [Department of Physics, West Virginia University, Morgantown, West Virginia 26506 (United States); Jackson, Cory D.; Kim, Justin F.; Hershkowitz, Noah [Department of Engineering Physics, The University of Wisconsin–Madison, Madison, Wisconsin 53706 (United States)

2014-10-15T23:59:59.000Z

124

Observation of Hybrid Soliton Vortex-Ring Structures in Bose-Einstein Condensates Naomi S. Ginsberg,1,* Joachim Brand,2  

E-Print Network (OSTI)

-Einstein condensates. We examine both their creation via soliton-vortex collisions and their subsequent development into vortex rings (VRs) [7,8] via the Kadomtsev-Petviashvili, or ``snake,'' instability [9]. In this Letter frequencies !z 2 21 Hz and !x !y 3:0!z in our 4-Dee magnetic trap [14]. We work at temperatures well below

Hau, Lene Vestergaard

125

Wave–vortex interactions in the nonlinear Schrödinger equation  

SciTech Connect

This is a theoretical study of wave–vortex interaction effects in the two-dimensional nonlinear Schrödinger equation, which is a useful conceptual model for the limiting dynamics of superfluid quantum condensates at zero temperature. The particular wave–vortex interaction effects are associated with the scattering and refraction of small-scale linear waves by the straining flows induced by quantized point vortices and, crucially, with the concomitant nonlinear back-reaction, the remote recoil, that these scattered waves exert on the vortices. Our detailed model is a narrow, slowly varying wavetrain of small-amplitude waves refracted by one or two vortices. Weak interactions are studied using a suitable perturbation method in which the nonlinear recoil force on the vortex then arises at second order in wave amplitude, and is computed in terms of a Magnus-type force expression for both finite and infinite wavetrains. In the case of an infinite wavetrain, an explicit asymptotic formula for the scattering angle is also derived and cross-checked against numerical ray tracing. Finally, under suitable conditions a wavetrain can be so strongly refracted that it collapses all the way onto a zero-size point vortex. This is a strong wave–vortex interaction by definition. The conditions for such a collapse are derived and the validity of ray tracing theory during the singular collapse is investigated.

Guo, Yuan, E-mail: yuanguo@cims.nyu.edu; Bühler, Oliver [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States)] [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States)

2014-02-15T23:59:59.000Z

126

Effect of Electric and Magnetic Fields on Spin Dynamics in the Resonant Electric Dipole Moment Experiment  

E-Print Network (OSTI)

A buildup of the vertical polarization in the resonant electric dipole moment (EDM) experiment [Y. F. Orlov, W. M. Morse, and Y. K. Semertzidis, Phys. Rev. Lett. 96, 214802 (2006)] is affected by a horizontal electric field in the particle rest frame oscillating at a resonant frequency. This field is defined by the Lorentz transformation of an oscillating longitudinal electric field and a uniform vertical magnetic one. The effect of a longitudinal electric field is significant, while the contribution from a magnetic field caused by forced coherent longitudinal oscillations of particles is dominant. The effect of electric field on the spin dynamics was not taken into account in previous calculations. This effect is considerable and leads to decreasing the EDM effect for the deuteron and increasing it for the proton. The formula for resonance strengths in the EDM experiment has been derived. The spin dynamics has been calculated.

Alexander J. Silenko

2007-10-02T23:59:59.000Z

127

Method for the assessment of airborne off-target pesticide spray concentrations due to aircraft wing-tip vortex  

E-Print Network (OSTI)

that spherical spray droplets are transported by a two dimensional parametric representation of a spray-engulfing aircraft wing-tip vortex pair. Two distinctive flow regions were considered for the spray-vortex dynamics. The first occurs in the vicinity...

Oliva, Sergio Eduardo

2012-06-07T23:59:59.000Z

128

Physica A 347 (2005) 363374 Dynamic roughening of the magnetic flux  

E-Print Network (OSTI)

Physica A 347 (2005) 363­374 Dynamic roughening of the magnetic flux landscape in YBa2Cu3O7�x C a ¼ 0:76ð3� and a growth exponent b ¼ 0:57ð6�: The roughening is caused by flux avalanches in a self in the context of other roughening systems in the presence of quenched disorder. r 2004 Elsevier B.V. All rights

Wijngaarden, Rinke J.

129

Magnetic Moments of Delta and Omega^- Baryons with Dynamical Clover Fermions  

E-Print Network (OSTI)

We calculate the magnetic dipole moment of the Delta(1232) and Omega^- baryons with 2+1-flavors of clover fermions on anisotropic lattices using a background magnetic field. This is the first dynamical calculation of these magnetic moments using a background field technique. The calculation for Omega^- is done at the physical strange quark mass, with the result in units of the physical nuclear magneton mu_Omega^-= -1.93(8)(12) (where the first error is statistical and the second is systematic) compared to the experimental number: -2.02(5). The Delta has been studied at three unphysical quark masses, corresponding to pion mass m_pi = 366, 438, and 548 MeV. The pion mass dependence is compared with the behavior obtained from chiral effective field theory.

C. Aubin; K. Orginos; V. Pascalutsa; M. Vanderhaeghen

2008-11-17T23:59:59.000Z

130

LONG-TERM EVOLUTION OF MAGNETIC AND DYNAMICAL PROPERTIES IN A SUNSPOT LIGHT BRIDGE  

SciTech Connect

Sunspot light bridges (LBs)-long bright lanes appearing in umbra-sometimes show dynamical behaviors such as plasma ejections, brightenings, and fast gas flows in the photosphere and lower chromosphere, but we have not understood what causes these dynamics. The Hinode Solar Optical Telescope successfully captured the entire period of the evolution of an LB formed at the southeast of the well-developed sunspot in NOAA Active Region 10953, allowing us to track how magnetic and dynamical properties change with time for 3.5 days. The LB produced chromospheric upward ejections intermittently and recurrently on 2007 April 30, and fewer upward ejections were observed on May 1. We found that G-band intensity features morphologically changed from cellar or patchy on April 30 to filamentary on May 1, although there were small changes in the magnetic flux density and inclination. This suggests that the chromospheric activity is related to the change of morphology in the photosphere. Fast gas flows and a pair of strong enhanced vertical electrical currents were also observed in the photosphere after the filamentary structures were dominant. The end of a large H{alpha} filament (or prominence) was extended very close to the LB on May 1, suggesting that the filamentary structures formed along the LB may be magnetically connected to the large H{alpha} filament and the gas flows may originate far from the LB region, although other mechanisms cannot be ruled out.

Shimizu, Toshifumi, E-mail: shimizu.toshifumi@isas.jaxa.jp [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan)

2011-09-01T23:59:59.000Z

131

On the interaction of mesoscopic magnetic textures with superconductors  

E-Print Network (OSTI)

, and established the required conditions for that. In particular, we studied two configurations for the magnetization distribution, namely the magnetic vortex and magnetic dot. We found that the dot was capable of simultaneously creating vortices...

Kayali, Mohammad Amin

2012-06-07T23:59:59.000Z

132

Vortex lines and transitions in superfluid hydrodynamics  

Science Journals Connector (OSTI)

...Preface to Vortices, dislocations, and line singularities in partial differential equations...Leslie and J. R. Ockendon. Vortex lines and transitions in superfluid hydrodynamics...nature and the motion of qunatized vortex lines. This paper illustrates the transitions...

1997-01-01T23:59:59.000Z

133

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...

Wang, Shuguang

2009-05-15T23:59:59.000Z

134

Monopole-Antimonopole Chains and Vortex Rings  

E-Print Network (OSTI)

We consider static axially symmetric solutions of SU(2) Yang-Mills-Higgs theory. The simplest such solutions represent monopoles, multimonopoles and monopole-antimonopole pairs. In general such solutions are characterized by two integers, the winding number m of their polar angle, and the winding number n of their azimuthal angle. For solutions with n=1 and n=2, the Higgs field vanishes at m isolated points along the symmetry axis, which are associated with the locations of m monopoles and antimonopoles of charge n. These solutions represent chains of m monopoles and antimonopoles in static equilibrium. For larger values of n, totally different configurations arise, where the Higgs field vanishes on one or more rings, centered around the symmetry axis. We discuss the properties of such monopole-antimonopole chains and vortex rings, in particular their energies and magnetic dipole moments, and we study the influence of a finite Higgs self-coupling constant on these solutions.

Burkhard Kleihaus; Jutta Kunz; Yasha Shnir

2004-05-19T23:59:59.000Z

135

New vortex ring configurations for the MAP dyon solutions  

Science Journals Connector (OSTI)

Electrically charged magnetic solutions of SU (2) Yang-Mills-Higgs theory with net zero topological charge has been obtained as axially symmetric saddle-point solutions in Ref. [1]. These solutions are characterized by an integer the winding number n of their azimuthal angle ? and an electric charge parameter 0vortex ring configuration with n=2 ?=0.65 and varying Higgs field strength. Our observations showed that beside the fundamental solution which is an electrically charged MAP solution there also exist two other branches of eclectically charged vortex ring solutions which both appear at ?=20.45. The difference in total energy between these two branches of solution is very small but the difference in diameter of vortex rings of the two branches is quite significant. Finding of a branching phenomena in presence of a fundamental MAP solution has been for the first time. In Ref. [2] new branching solutions occur for the electrically neutral case in presence of fundamental vortex ring solutions but not for the fundamental MAP solution.

2014-01-01T23:59:59.000Z

136

Vortex strings in electric dipole radiation near a mirror  

Science Journals Connector (OSTI)

Abstract The energy flow pattern of the radiation emitted by an oscillating electric dipole near a mirror has a complicated structure, including numerous singularities and vortices. We consider the flow lines of energy in the plane through the surface normal and the oscillation direction of the dipole. It is shown that the vortices are due to the vanishing of the magnetic field at their centers. The locations of the vortices have the appearance of beads on strings, and there are four such strings. The rotation direction of the energy flow for each vortex on a given string is the same. There are two strings with clockwise rotation and two strings with counterclockwise rotation. Field lines of energy flow either start or end at the center of a vortex. For a given string, field lines end at each vortex or field lines start at each vortex. There are two strings on which field lines end at the centers of the vortices, and there are two strings on which field lines start inside the vortices.

Xin Li; Henk F. Arnoldus

2013-01-01T23:59:59.000Z

137

Magnetism  

Science Journals Connector (OSTI)

Historically, magnetism is related to rock magnetism, due to a few minerals exhibiting spontaneous magnetization. Attractive properties of magnetite were already known in Antiquity and were used for navigation...

Guillaume Morin

1998-01-01T23:59:59.000Z

138

Memory-bit selection and recording by rotating fields in vortex-core cross-point architecture  

SciTech Connect

In one of our earlier studies [Appl. Phys. Lett. 92, 022509 (2008)], we proposed a concept of robust information storage, recording and readout, which can be implementaed in nonvolatile magnetic random-access memories and is based on the energetically degenerated twofold ground states of vortex-core magnetizations. In the present study, we experimentally demonstrate reliable memory-bit selection and information recording in vortex-core cross-point architecture, specifically using a two-by-two vortex-state disk array. In order to efficiently switch a vortex core positioned at the intersection of crossed electrodes, two orthogonal addressing electrodes are selected, and then two Gaussian pulse currents of optimal pulse width and time delay are applied. Such tailored pulse-type rotating magnetic fields which occurs only at the selected intersection is prerequisite for a reliable memory-bit selection and low-power-consumption recording of information in the existing cross-point architecture.

Yu, Y. -S.; Jung, H.; Lee, K. -S.; Fischer, P.; Kim, S. -K.

2010-10-21T23:59:59.000Z

139

magnetism  

Science Journals Connector (OSTI)

magnetism [A class of physical phenomena associated with moving electricity, including the mutual mechanical forces among magnets and electric currents] ? Magnetismus m

2014-08-01T23:59:59.000Z

140

Particle Dynamics around Riessner-Nordstr\\"om Black Hole with Magnetic Field  

E-Print Network (OSTI)

We investigate the dynamics of a neutral and a charged particle around the Reissner-Nordstr\\"om (RN) black hole immersed in magnetic field. We are interested to explore the conditions under which the moving charged particle can escape to infinity after collision with another neutral particle or a photon in the vicinity of the BH. We have calculated the expressions of the escape velocity. Further we have studied that how does the presence of magnetic field in the vicinity of BH, effect the motion of the orbiting particle. There are more than one stable regions if we consider the magnetic field in the accretion disk of BH so the stability of ISCO increases in the presence of magnetic field. We have also discussed the Lyapunov exponent in detail. Time-like geodesics of the moving particle are also studied. It is observed that the particle goes closer to the extremal RN-BH as compared to the case when it is moving around RN-BH.

Majeed, Bushra; Jamil, Mubasher

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

Particle Dynamics around Riessner-Nordström Black Hole with Magnetic Field  

E-Print Network (OSTI)

We investigate the dynamics of a neutral and a charged particle around the Reissner-Nordstr\\"om (RN) black hole immersed in magnetic field. We are interested to explore the conditions under which the moving charged particle can escape to infinity after collision with another neutral particle or a photon in the vicinity of the BH. We have calculated the expressions of the escape velocity. Further we have studied that how does the presence of magnetic field in the vicinity of BH, effect the motion of the orbiting particle. There are more than one stable regions if we consider the magnetic field in the accretion disk of BH so the stability of ISCO increases in the presence of magnetic field. We have also discussed the Lyapunov exponent in detail. Time-like geodesics of the moving particle are also studied. It is observed that the particle goes closer to the extremal RN-BH as compared to the case when it is moving around RN-BH.

Bushra Majeed; Saqib Hussain; Mubasher Jamil

2014-11-18T23:59:59.000Z

142

Flame–vortex interaction in a reacting vortex ring  

Science Journals Connector (OSTI)

Direct numerical simulations are used to study the flame–vortex interaction in a laminar reacting vortex ring. The chemical reaction occurs by a one-step Arrhenius-type reaction that mimics the combustion of typical hydrocarbon and air. The ring is generated by an axisymmetric jet that is impulsed to emit a cold fuel through a nozzle. The fuel enters a quiescent ambient at a much higher temperature. By adjusting the ratio of the ambient and fuel temperatures the ignition either occurs during the formation or post-formation phase of the ring. When ignition occurs during the formation phase of the ring the bulk of combustion is by a flame at the front of the vortex bubble. When ignition is delayed until after the formation phase most of the reaction occurs inside the vortex ring. It is found that premixing the fuel and the oxidizer enhances the amount of product formation. The heat released from the reaction significantly affects production redistribution and diffusion of the vorticity throughout the field. The results of the simulations also reveal that the heat of reaction affects the strain rate fields differently depending on when the ignition of the ring occurs.

J. S. Hewett; C. K. Madnia

1998-01-01T23:59:59.000Z

143

Canonicalization and symplectic simulation of the gyrocenter dynamics in time-independent magnetic fields  

SciTech Connect

The gyrocenter dynamics of charged particles in time-independent magnetic fields is a non-canonical Hamiltonian system. The canonical description of the gyrocenter has both theoretical and practical importance. We provide a general procedure of the gyrocenter canonicalization, which is expressed by the series of a small variable ? depending only on the parallel velocity u and can be expressed in a recursive manner. We prove that the truncation of the series to any given order generates a set of exact canonical coordinates for a system, whose Lagrangian approximates to that of the original gyrocenter system in the same order. If flux surfaces exist for the magnetic field, the series stops simply at the second order and an exact canonical form of the gyrocenter system is obtained. With the canonicalization schemes, the canonical symplectic simulation of gyrocenter dynamics is realized for the first time. The canonical symplectic algorithm has the advantage of good conservation properties and long-term numerical accuracy, while avoiding numerical instability. It is worth mentioning that explicitly expressing the canonical Hamiltonian in new coordinates is usually difficult and impractical. We give an iteration procedure that is easy to implement in the original coordinates associated with the coordinate transformation. This is crucial for modern large-scale simulation studies in plasma physics. The dynamics of gyrocenters in the dipole magnetic field and in the toroidal geometry are simulated using the canonical symplectic algorithm by comparison with the higher-order non symplectic Runge-Kutta scheme. The overwhelming superiorities of the symplectic method for the gyrocenter system are evidently exhibited.

Zhang, Ruili; Tang, Yifa; Zhu, Beibei [LSEC, ICMSEC, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190 (China)] [LSEC, ICMSEC, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190 (China); Liu, Jian, E-mail: jliuphy@ustc.edu.cn; Xiao, Jianyuan [Department of Modern Physics and Collaborative Innovation Center for Advanced Fusion Energy and Plasma Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [Department of Modern Physics and Collaborative Innovation Center for Advanced Fusion Energy and Plasma Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China); Qin, Hong [Department of Modern Physics and Collaborative Innovation Center for Advanced Fusion Energy and Plasma Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China) [Department of Modern Physics and Collaborative Innovation Center for Advanced Fusion Energy and Plasma Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China); Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

2014-03-15T23:59:59.000Z

144

CORONAL MAGNETIC FIELD MEASUREMENT FROM EUV IMAGES MADE BY THE SOLAR DYNAMICS OBSERVATORY  

SciTech Connect

By measuring the geometrical properties of the coronal mass ejection (CME) flux rope and the leading shock observed on 2010 June 13 by the Solar Dynamics Observatory (SDO) mission's Atmospheric Imaging Assembly we determine the Alfven speed and the magnetic field strength in the inner corona at a heliocentric distance of {approx}1.4 Rs. The basic measurements are the shock standoff distance ({Delta}R) ahead of the CME flux rope, the radius of curvature of the flux rope (R{sub c}), and the shock speed. We first derive the Alfvenic Mach number (M) using the relationship, {Delta}R/R{sub c} = 0.81[({gamma}-1) M{sup 2} + 2]/[({gamma}+1)(M{sup 2} - 1)], where {gamma} is the only parameter that needed to be assumed. For {gamma} = 4/3, the Mach number declined from 3.7 to 1.5 indicating shock weakening within the field of view of the imager. The shock formation coincided with the appearance of a type II radio burst at a frequency of {approx}300 MHz (harmonic component), providing an independent confirmation of the shock. The shock compression ratio derived from the radio dynamic spectrum was found to be consistent with that derived from the theory of fast-mode MHD shocks. From the measured shock speed and the derived Mach number, we found the Alfven speed to increase from {approx}140 km s{sup -1} to 460 km s{sup -1} over the distance range 1.2-1.5 Rs. By deriving the upstream plasma density from the emission frequency of the associated type II radio burst, we determined the coronal magnetic field to be in the range 1.3-1.5 G. The derived magnetic field values are consistent with other estimates in a similar distance range. This work demonstrates that the EUV imagers, in the presence of radio dynamic spectra, can be used as coronal magnetometers.

Gopalswamy, Nat; Akiyama, Sachiko; Maekelae, Pertti; Yashiro, Seiji [NASA Goddard Space Flight Center, Greenbelt, MD 20771-0001 (United States); Nitta, Nariaki [Lockheed-Martin Solar and Astrophysics Laboratory, Palo Alto, CA 94304 (United States)

2012-01-01T23:59:59.000Z

145

Role of the core energy in the vortex Nernst effect  

Science Journals Connector (OSTI)

We present an analytical study of diamagnetism and transport in a film with superconducting phase fluctuations, formulated in terms of vortex dynamics within the Debye-Hückel approximation. We find that the diamagnetic and Nernst signals decay strongly with temperature in a manner that is dictated by the vortex core energy. Using the theory to interpret Nernst measurements of underdoped La2?xSrxCuO4 above the critical temperature regime, we obtain a considerably better fit to the data than a fit based on Gaussian order-parameter fluctuations. Our results indicate that the core energy in this system scales roughly with the critical temperature and is significantly smaller than expected from BCS theory. Furthermore, it is necessary to assume that the vortex mobility is much larger than the Bardeen-Stephen value in order to reconcile conductivity measurements with the same vortex picture. Therefore, either the Nernst signal is not due to fluctuating vortices, or vortices in underdoped La2?xSrxCuO4 have highly unconventional properties.

Gideon Wachtel and Dror Orgad

2014-11-11T23:59:59.000Z

146

Nano and picosecond magnetization dynamics of weakly coupled CoFe/Cr/NiFe trilayers studied by a multitechnique approach  

Science Journals Connector (OSTI)

We present results on the magnetization dynamics in heterostructures of the CoFe/Cr/NiFe type. We have employed a combination of different layer-selective methods covering a broad range from quasistatic hysteresis measurements by x-ray magnetic circular dichroism (XMCD), over time-resolved photoemission electron microscopy (PEEM) at subnanosecond timescales to high-frequency ferromagnetic resonance (FMR) experiments. With increasing driving frequency, we found a different influence of the coupling between the two ferromagnetic layers on the dynamic behavior. Employing the spatial resolution of the PEEM method, we have been able to discern various dynamic responses in different regions of the sample that could be attributed to magnetodynamic processes with a different degree of coupling. In conjunction with the complementary FMR and XMCD measurements, we attribute the inhomogeneous influence of interlayer coupling to a shift from domain-wall-motion-dominated dynamics at low frequencies to precession-dominated dynamics at higher frequencies.

A. M. Kaiser; C. Schöppner; F. M. Römer; C. Hassel; C. Wiemann; S. Cramm; F. Nickel; P. Grychtol; C. Tieg; J. Lindner; C. M. Schneider

2011-10-10T23:59:59.000Z

147

Helical magnetocumulative generators with magnetic flux amplification: Comparative advantages of amplification schemes and the operational efficiency of generators with dynamic transformation  

Science Journals Connector (OSTI)

The amplification capabilities of two types of helical magnetocumulative generators based on the cascade scheme of magnetic flux amplification, generators with dynamic transformation, and those with transformer ....

A. A. Bazanov

2011-09-01T23:59:59.000Z

148

Magnetism  

Science Journals Connector (OSTI)

... dipoles in applied fields". It deals with the classical (Langevin) theory of para-magnetism, anisotropy fields and magnetic measurements. In the next chapter "Atomic structure" the author ... special relevance to ferrites and the inclusion of a quite lengthy discussion of Pauli para-magnetism and of Stoner's treatment of itinerant electron ferromagnetism, though it does much to ...

E. W. LEE

1972-03-31T23:59:59.000Z

149

Polarization-selective vortex-core switching by tailored orthogonal Gaussian-pulse currents  

SciTech Connect

We experimentally demonstrate low-power-consumption vortex-core switching in magnetic nanodisks using tailored rotating magnetic fields produced with orthogonal and unipolar Gaussian-pulse currents. The optimal width of the orthogonal pulses and their time delay are found, from analytical and micromagnetic numerical calculations, to be determined only by the angular eigenfrequency {omega}{sub D} for a given vortex-state disk of polarization p, such that {sigma}=1/{omega}{sub D} and ?{Delta}t={pi}/2 p/{omega}{sub D} . The estimated optimal pulse parameters are in good agreement with the experimental results. This work lays a foundation for energy-efficient information recording in vortex-core cross-point architecture.

Jung, H.; Choi, Y. -S.; Yoo, M. -W.; Im, M. -Y.; Kim, S. -K.

2010-10-13T23:59:59.000Z

150

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

151

Vortex molecules in Bose-Einstein condensates  

E-Print Network (OSTI)

Stable vortex dimers are known to exist in coherently coupled two component Bose-Einstein condensates (BECs). We construct stable vortex trimers in three component BECs and find that the shape can be controlled by changing the internal coherent (Rabi) couplings. Stable vortex N-omers are also constructed in coherently coupled N-component BECs. We classify all possible N-omers in terms of the mathematical graph theory. Next, we study effects of the Rabi coupling in vortex lattices in two-component BECs. We find how the vortex lattices without the Rabi coupling known before are connected to the Abrikosov lattice of integer vortices with increasing the Rabi coupling. In this process, vortex dimers change their partners in various ways at large couplings. We then find that the Abrikosov lattices are robust in three-component BECs.

Muneto Nitta; Minoru Eto; Mattia Cipriani

2013-07-16T23:59:59.000Z

152

Reconnection of vortex filaments and Kolmogorov spectrum  

E-Print Network (OSTI)

The energy spectrum of the 3D velocity field, induced by collapsing vortex filaments is studied. One of the aims of this work is to clarify the appearance of the Kolmogorov type energy spectrum $E(k)\\varpropto k^{-5/3}$, observed in many numerical works on discrete vortex tubes (quantized vortex filaments in quantum fluids). Usually, explaining classical turbulent properties of quantum turbulence, the model of vortex bundles, is used. This model is necessary to mimic the vortex stretching, which is responsible for the energy transfer in classical turbulence. In our consideration we do not appeal to the possible "bundle arrangement" but explore alternative idea that the turbulent spectra appear from singular solution, which describe the collapsing line at moments of reconnection. One more aim is related to an important and intensively discussed topic - a role of hydrodynamic collapse in the formation of turbulent spectra. We demonstrated that the specific vortex filament configuration generated the spectrum $E...

Nemirovskii, Sergey K

2014-01-01T23:59:59.000Z

153

Quantum Kinematics of Bosonic Vortex Loops  

SciTech Connect

Poisson structure for vortex filaments (loops and arcs) in 2D ideal incompressible fluid is analyzed in detail. Canonical coordinates and momenta on coadjoint orbits of the area-preserving diffeomorphism group, associated with such vortices, are found. The quantum space of states in the simplest case of ''bosonic'' vortex loops is built within a geometric quantization approach to the description of a quantum fluid. Fock-like structure and non-local creation and annihilation operators of quantum vortex filaments are introduced.

Goldin, G.A.; Owczarek, R.; Sharp, D.H.

1999-05-06T23:59:59.000Z

154

Coherent dynamical recoupling of diffusion-driven decoherence in magnetic resonance  

E-Print Network (OSTI)

During recent years, dynamical decoupling (DD) has gained relevance as a tool for manipulating quantum systems and extracting information from them. This is particularly relevant for spins involved in nuclear magnetic resonance (NMR), where DD sequences can be used to prolong quantum coherences, or for selectively couple/decouple the effects imposed by random environmental fluctuations. In this Letter, we show that one can exploit these concepts in order to selectively recouple diffusion processes in restricted spaces. The ensuing method provides a novel tool to measure restriction lengths in confined systems such as capillaries, pores or cells. The principles of this method for selectively recoupling diffusion-driven decoherence, its standing within the context of diffusion NMR, and corroborating experiments, are presented.

Gonzalo A. Alvarez; Noam Shemesh; Lucio Frydman

2014-09-07T23:59:59.000Z

155

Cherenkov resonances in vortex dissipation in superconductors B. I. Ivlev and S. Mejia-Rosales  

E-Print Network (OSTI)

, Mexico M. N. Kunchur Department of Physics and Astronomy, University of South Carolina, Columbia, South-two superconductors the magnetic flux is carried by vortices. If the transport electric current greatly exceeds in the crystal the dissipa- tion increases due to Cherenkov emission of sound waves. Each moving vortex creates

Kunchur, Milind N.

156

Photonic Labyrinths: Two-Dimensional Dynamic Magnetic Assembly and in Situ Solidification  

Science Journals Connector (OSTI)

A NdFeB magnet placed underneath the sample can be moved freely for convenient control of the strength and orientation of the external magnetic fields. ... Similar to the well-developed “magnetic hole” effect in which nonmagnetic particles dispersed in a magnetized ferrofluid solution behave as magnetic “holes”, the nonmagnetic templates exposed to the Fe3O4 CNCs behave as “reverse magnets” in an external magnetic field due to the difference in magnetization. ... Berkovsky, B. M.; Medvedev, V. F.; Krakov, M. S. Magnetic Fluids Engineering Applications; Oxford Science Publications: Oxford, 1993. ...

Qiao Zhang; Michael Janner; Le He; Mingsheng Wang; Yongxing Hu; Yu Lu; Yadong Yin

2013-03-06T23:59:59.000Z

157

Vortex Hydro Energy Develops Transformational Technology to Harness...  

Energy Savers (EERE)

Vortex Hydro Energy Develops Transformational Technology to Harness Energy from Water Currents Vortex Hydro Energy Develops Transformational Technology to Harness Energy from Water...

158

Spontaneous vortex phase and pinning in ferromagnetic-superconducting systems  

E-Print Network (OSTI)

of epsilon10 as a function of rho0lambda for the case when n = 1, lambdaxi = 10,R1 = lambda,R2 = 2lambda and deltam = 10. . . . . . . . . . . . . . . 31 ix FIGURE Page 12 A superconducting thin film pierced by a ferromagnetic nano rod of radius R, length L... circle of radius rho0 that depends on the radii and magnetization per unit area of the annulus, and on the SC pene- tration depth lambda. In section five I focus on pinning and spontaneous vortex creation by a ferromagnetic rod which penetrates...

Kayali, Mohammad Amin

2004-09-30T23:59:59.000Z

159

Magnetism  

Science Journals Connector (OSTI)

... THIS is a good book, and we are glad to see the subject of magnetism fully treated in a popularly written text-book. It is a second edition of ... of importance, accuracy, and exhaustiveness, places the present treatise, as far as terrestrial magnetism is concerned, much before any similar book with which we are acquainted. The correction ...

JAMES STUART

1872-03-07T23:59:59.000Z

160

Dynamics of Particles Around a Schwarzschild-like Black Hole in the Presence of Quintessence and Magnetic Field  

E-Print Network (OSTI)

We have investigated the dynamics of a neutral and a charged particle around a static and spherically symmetric black hole in the presence of quintessence matter and external magnetic field. We explore the conditions under which the particle moving around the black hole could escape to infinity after colliding with another particle. The innermost stable circular orbit (ISCO) for the particles are studied in detail. Mainly the dependence of ISCO on dark energy and on the presence of external magnetic field in the vicinity of black hole is discussed. By using the Lyapunov exponent, we compare the stabilities of the orbits of the particles in the presence and absence of dark energy and magnetic field. The expressions for the center of mass energies of the colliding particles near the horizon of the black hole are derived. The effective force on the particle due to dark energy and magnetic field in the vicinity of black hole is also discussed.

Mubasher Jamil; Saqib Hussain; Bushra Majeed

2014-04-28T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" from the National Library of EnergyBeta (NLEBeta).
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161

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

2011-09-22T23:59:59.000Z

162

Interaction of mesoscopic magnetic textures with superconductors  

E-Print Network (OSTI)

Here we report a method to calculate the vortex and magnetization arrangement for a system of interacting superconductors and ferromagnets separated in space. The method is based on static London-Maxwell equations and the corresponding energy...

Erdin, S.; Kayali, AF; Lyuksyutov, Igor F.; Pokrovsky, Valery L.

2002-01-01T23:59:59.000Z

163

Vortex Ring Interaction with a Particle Layer: Implications for Sediment Transport  

E-Print Network (OSTI)

resuspension has been studied much less. This is an important mechanism, however, as it represents an integral conducted to study particle resuspension by vortex rings colliding with a particle bed. The dynamics at the resuspension onset are investigated, showing that the deformable particle bed resembles a free slip boundary

Dalziel, Stuart

164

Resuspension onset and crater erosion by a vortex ring interacting with a particle layer  

E-Print Network (OSTI)

Resuspension onset and crater erosion by a vortex ring interacting with a particle layer N. Bethke://pof.aip.org/features/most_downloaded Information for Authors: http://pof.aip.org/authors #12;PHYSICS OF FLUIDS 24, 063301 (2012) Resuspension onset layer. The flow dynamics during the onset of particle resuspension are analysed using particle image

Dalziel, Stuart

165

Stability of vortex solitons in a photorefractive optical lattice  

E-Print Network (OSTI)

://www.njp.org/ DOI: 10.1088/1367-2630/6/1/047 Abstract. Stability of on- and off-site vortex solitons with unit stable than off-site ones. Increasing the DC field stabilizes both types of vortex solitons. Contents 1. Introduction 2 2. Off-site vortex solitons 4 3. On-site vortex solitons 9 4. Summary 11 Acknowledgments 11

Yang, Jianke

166

Ultra-Low NOx Advanced Vortex Combustor  

SciTech Connect

An ultra 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 (USDOE NETL) test facility 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/UHC emissions of 4/4/0 ppmv (all emissions are at 15% O2 dry). The design also achieved less than 3 ppmv NOx with combustion efficiencies in excess of 99.5%. The design demonstrated tremendous 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, a pressure drop of 1.75% was measured which is significantly lower than conventional gas turbine combustors. Potentially, this lower pressure drop characteristic of the AVC concept translates into overall gas turbine cycle efficiency improvements of up to one full percentage point. The relatively high velocities and low pressure drops achievable with this technology make the AVC approach an attractive alternative for syngas fuel applications.

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

2006-05-01T23:59:59.000Z

167

ULTRA-LOW NOX ADVANCED VORTEX COMBUSTOR  

SciTech Connect

An ultra 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 (USDOE NETL) test facility 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/UHC emissions of 4/4/0 ppmv (all emissions are at 15% O2 dry). The design also achieved less than 3 ppmv NOx with combustion efficiencies in excess of 99.5%. The design demonstrated tremendous 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, a pressure drop of 1.75% was measured which is significantly lower than conventional gas turbine combustors. Potentially, this lower pressure drop characteristic of the AVC concept translates into overall gas turbine cycle efficiency improvements of up to one full percentage point. The relatively high velocities and low pressure drops achievable with this technology make the AVC approach an attractive alternative for syngas fuel applications.

Ryan G. Edmonds; Robert C. Steele; Joseph T. Williams; Douglas L. Straub; Kent H. Casleton; Avtar Bining

2006-05-01T23:59:59.000Z

168

Lower pseudogap phase of Mott insulators: A spin/vortex liquid state  

Science Journals Connector (OSTI)

The pseudogap phase is considered to be a new state of matter in the phase string model of the doped Mott insulator, which is composed of two distinct regimes known as the upper and lower pseudogap phases, respectively. The former corresponds to the formation of spin-singlet pairing, the magnetic characterizations of which have been recently studied [Phys. Rev. B 72, 104520 (2005)]. The latter, as a low-temperature regime of the pseudogap phase, is systematically explored in this work, which is characterized by the formation of the Cooper pair amplitude and described by a generalized Ginzburg-Landau theory. Elementary excitation in this phase is a charge-neutral object carrying spin-1?2 and locking with a supercurrent vortex, known as a spinon-vortex composite. Such a lower pseudogap phase can be regarded as a vortex liquid state due to the presence of free spinon vortices. Here thermally excited spinon vortices destroy the phase coherence and are responsible for the nontrivial Nernst effect and diamagnetism. The transport entropy and core energy associated with a spinon vortex are determined by the spin degrees of freedom. Such a spontaneous vortex liquid phase can be also considered as a spin liquid with a finite correlation length and gaped S=1?2 excitations, where a resonancelike nonpropagating spin mode emerges at the antiferromagnetic wavevector (?,?) with a doping-dependent characteristic energy. The superconducting phase is closely related to the lower pseudogap phase by a topological transition with spinon vortices and antivortices forming bound pairs and the emergence of fermionic quasiparticles as holon-spinon-vortex bound objects. A quantitative phase diagram in the parameter space of doping, temperature, and magnetic field is determined. Comparisons with experiments are also made.

Zheng-Yu Weng and Xiao-Liang Qi

2006-10-26T23:59:59.000Z

169

Effects of spin on the dynamics of the 2D Dirac oscillator in the magnetic cosmic string background  

E-Print Network (OSTI)

In this work the dynamics of a 2D Dirac oscillator in the spacetime of a magnetic cosmic string is considered. It is shown that earlier approaches to this problem have neglected a $\\delta$ function contribution to the full Hamiltonian, which comes from the Zeeman interaction. The inclusion of spin effects leads to results which confirm a modified dynamics. Based on the self-adjoint extension method, we determined the most relevant physical quantities, such as energy spectrum, wave functions and the self-adjoint extension parameter by applying boundary conditions allowed by the system.

Fabiano M. Andrade; Edilberto O. Silva

2014-03-17T23:59:59.000Z

170

Effects of spin on the dynamics of the 2D Dirac oscillator in the magnetic cosmic string background  

E-Print Network (OSTI)

In this work the dynamics of a 2D Dirac oscillator in the spacetime of a magnetic cosmic string is considered. It is shown that earlier approaches to this problem have neglected a $\\delta$ function contribution to the full Hamiltonian, which comes from the Zeeman interaction. The inclusion of spin effects leads to results which confirm a modified dynamics. Based on the self-adjoint extension method, we determined the most relevant physical quantities, such as energy spectrum, wave functions and the self-adjoint extension parameter by applying boundary conditions allowed by the system.

Andrade, Fabiano M

2014-01-01T23:59:59.000Z

171

Coronal Magnetic Field Measurement from EUV Images made by the Solar Dynamics Observatory  

E-Print Network (OSTI)

By measuring the geometrical properties of the coronal mass ejection (CME) flux rope and the leading shock observed on 2010 June 13 by the Solar Dynamics Observatory (SDO) mission's Atmospheric Imaging Assembly (AIA) we determine the Alfv\\'en speed and the magnetic field strength in the inner corona at a heliocentric distance of ~ 1.4 Rs. The basic measurements are the shock standoff distance (deltaR) ahead of the CME flux rope, the radius of curvature of the flux rope (Rc), and the shock speed. We first derive the Alfv\\'enic Mach number (M) using the relationship, deltaR/Rc = 0.81[(gamma-1) M^2 + 2]/[(gamma+1)(M^2-1)], where gamma is the only parameter that needed to be assumed. For gamma =4/3, the Mach number declined from 3.7 to 1.5 indicating shock weakening within the field of view of the imager. The shock formation coincided with the appearance of a type II radio burst at a frequency of ~300 MHz (harmonic component), providing an independent confirmation of the shock. The shock compression ratio derived...

Gopalswamy, Nat; Akiyama, Sachiko; Mäkelä, Pertti; Yashiro, Seiji

2011-01-01T23:59:59.000Z

172

Laboratory studies of the dynamic of resonance cones formation in magnetized plasmas  

SciTech Connect

The paper is devoted to experimental studies of formation of resonance cones in magnetized plasmas by pulsed RF source in the lower-hybrid (whistler) and the upper-hybrid frequency ranges. It is shown that in both frequency ranges, resonance cones exhibit similar dynamics after switching-on the RF source: at first, wide maxima of radiation are formed in non-resonance directions, which then become narrower, with their direction approaching the resonance one. While the resonance cones are being formed, one observes a fine structure in the form of secondary radiation maxima. It is shown that the characteristic formation time of stationary resonance cones is determined by the minimal value of the group velocity of the quasi-electrostatic waves excited by the antenna. In the low-temperature plasma, this value is limited in the lower-hybrid frequency range by the spatial spectrum of the emitting antenna and in the upper-hybrid range, by the effects of spatial plasma dispersion.

Nazarov, V. V.; Starodubtsev, M. V.; Kostrov, A. V. [Russian Academy of Sciences, Institute of Applied Physics, Nizhny Novgorod (Russian Federation)

2013-03-15T23:59:59.000Z

173

Dynamics of the Solar Magnetic Network: Two-dimensional MHD Simulations  

E-Print Network (OSTI)

The aim of this work is to identify the physical processes that occur in the network and contribute to its dynamics and heating. We model the network as consisting of individual flux tubes with a non-potential field structure that are located in intergranular lanes. With a typical horizontal size of 200 km at the base of the photosphere, they expand upward and merge with their neighbors at a height of about 600 km. Above a height of approximately 1000 km the magnetic field starts to become uniform. Waves are generated in this medium by means of motions at the lower boundary. We focus on transverse driving, which generates both fast and slow waves within a flux tube and acoustic waves at the interface of the tube and the field-free medium. The acoustic waves at the interface are due to compression of the gas on one side of the flux tube and expansion on the other. These waves travel upward along the two sides of the (2D) flux tube and enter it, where they become longitudinal waves. For impulsive excitation with a time constant of 120 s, we find that a dominant feature is the creation of vortical motions that propagate upward. We have identified an efficient mechanism for the generation of longitudinal waves and shock formation in the chromospheric part of the flux concentration. We examine some broad implications of our results.

S. S. Hasan; A. A. van Ballegoiijen; W. Kalkofen; O. Steiner

2005-03-24T23:59:59.000Z

174

Numerical simulation of a viscous vortex ring interaction with a density interface  

SciTech Connect

When a vortex-dominated flow interacts with a sharp density interface, the dynamics are characterized by the interaction of baroclinically generated vorticity with the already existing vorticity field. This can be seen in many natural and technology settings; examples are the interaction of a ship or submarine wake with a thermocline, the collision of a buoyant thermal with a temperature inversion, and the interaction of a vortex flow with a flame front. This problem also serves as a generic model for turbulent mixing and entrainment processes across sharp density interfaces. The interaction between vortices and a free surface, with corresponds to the case where the density jump is very large, has been studied fairly extensively, both experimentally and computationally. By comparison, the literature for the more general case of vortex pairs and rings interacting with sharp density interfaces is relatively sparse. Experiments and numerical studies have been performed, but the numerical simulations were confined primarily to vortex pairs, restricted to the inviscid case, and the effect of density variation modeled under the Boussinesq approximation. The experiments were also confined to the Boussinesq regime. In this paper, we study the motion of a vortex ring in a sharply stratified, viscous fluid via a numerical solution of the full Navier-Stokes equations with finite-amplitude density variation. both Boussinesq and non-Boussinesq flow regimes will be studied, the effect of viscosity on the interaction will be examined, and three-dimensional aspects of the motion will be addressed, such as Widnall instability of the vortex ring and vortex reconnection at the interface.

Marcus, D.L.; Bell, J.B.

1990-10-01T23:59:59.000Z

175

Reversal modes in magnetic nanotubes  

E-Print Network (OSTI)

The magnetic switching of ferromagnetic nanotubes is investigated as a function of their geometry. Two independent methods are used: Numerical simulations and analytical calculations. It is found that for long tubes the reversal of magnetization is achieved by two mechanism: The propagation of a transverse or a vortex domain wall depending on the internal and external radii of the tube.

P. Landeros; S. Allende; J. Escrig; E. Salcedo; D. Altbir; E. E. Vogel

2006-11-08T23:59:59.000Z

176

398 IEEE TRANSACTIONS ON MAGNETICS, VOL. 42, NO. 3, MARCH 2006 Introducing Dynamic Behavior of Magnetic Materials  

E-Print Network (OSTI)

of Magnetic Materials Into a Model of a Switched Reluctance Motor Drive F. Sixdenier, L. Morel, and J. P, we present the model of an ultrafast switched reluctance motor, in which the control of the power switched reluctance motor (SRM) drive [9], [10] designed by the Labora- toire de genie industriel et

Boyer, Edmond

177

Low-temperature dynamics of magnetic colloids studied by time-resolved small-angle neutron scattering  

Science Journals Connector (OSTI)

The dynamics of ordering and relaxation processes in magnetic colloids has been studied by means of stroboscopic small angle neutron scattering techniques in an oscillating magnetic field. Surfactant stabilized ferrofluids (FFs) of Fe3O4 and Co nanoparticles have been investigated as a function of temperature and frequency and compared to a solid Cu alloy with 0.8vol% Co precipitates. This technique allowed elucidating the dynamical nature of the locally ordered domains in both ferrofluids as “living objects” becoming arrested below the freezing temperature of the solvent. The time-dependent intensities have been analyzed in terms of Langevin statistics including dynamical interparticle structure factors, which scale with the square of the Langevin function. The local ordering is mainly determined by the effective dipole-dipole interaction, which is enhanced by the partial alignment of the particle moments in an external magnetic field. Starting from the frozen state, the amount of freely rotating particle moments increases continuously with increasing temperature. The dynamical structure factors describing the hexagonal (Fe3O4-FF) or chainlike (Co-FF) ordering reach a maximum around the melting temperature. The alignment of particle moments along the applied field is governed by the fast Brownian rotation of individual nanoparticles and small aggregates, while the magnetic relaxation of longer dipolar chains and local hexagonal domains is much slower. In contrast, no field-induced interparticle correlations occur in the diluted solid CuCo alloy where the moment relaxation is purely of fast Néel type, which—due to a low anisotropy constant—follows the oscillating field at all temperatures.

A. Wiedenmann; U. Keiderling; M. Meissner; D. Wallacher; R. Gähler; R. P. May; S. Prévost; M. Klokkenburg; B. H. Erné; J. Kohlbrecher

2008-05-15T23:59:59.000Z

178

Specification of fields quality in the interaction region magnets of the high luminosity LHC based on dynamic aperture  

E-Print Network (OSTI)

New large aperture Inner Triplet quadrupoles, separation dipoles and the nearby matching quadrupoles will be installed in the low-beta interaction regions (IR) of the high luminosity LHC upgrade (HL-LHC) [1]. The large aperture is necessary for accommodating the increased beam size due to much higher beta functions in these magnets for the low collision optics. The high beta functionswill amplify the effects of field errors in the new magnets leading to a smaller dynamic aperture (DA). It is, therefore, critical to evaluate the impact of these errors on the DA and specify the magnet field quality (FQ) satisfying an acceptable DA while being realistically achievable. The study is performed for the HL-LHC lattice layouts SLHCV3.1b and HLLHCV1.0 for collision and injection energies.

Nosochkov, Y; Wang, M H; Fartoukh, S; Giovannozzi, M; De Maria, R; McIntosh, E

2014-01-01T23:59:59.000Z

179

Dynamic high pressure process for fabricating superconducting and permanent magnetic materials  

DOE Patents (OSTI)

Shock wave formation of superconductive ceramic oxide electric and magnetic circuit elements with improved microstructures and mechanical properties. 10 figs.

Nellis, W.J.; Maple, M.B.; Geballe, T.H.

1987-10-23T23:59:59.000Z

180

Bulk nanocomposite magnets produced by dynamic shock compaction K. H. Chen and Z. Q. Jin  

E-Print Network (OSTI)

single-phaselike behavior, indicating effective exchange coupling between hard and soft magnetic phases. © 2004 American Institute of Physics. DOI: 10.1063/1.1760834 The figure of merit for a permanent magnet of bulk exchange-coupled nanocomposite magnets still remains a great challenge. Shock compaction employs

Wang, Zhong L.

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

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

SciTech Connect

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

182

‘Optimal’ vortex rings and aquatic propulsion mechanisms  

Science Journals Connector (OSTI)

...vortex rings and aquatic propulsion mechanisms P. F. Linden...fluid mechanics behind these propulsion mechanisms and show that...over the cycle. 4. FISH PROPULSION BY UNDULATORY SWIMMING Most marine organisms have only discrete...

2004-01-01T23:59:59.000Z

183

Polarization dependent forces in optical vortex pipeline  

Science Journals Connector (OSTI)

We study both, theoretically and in experiments, the dependence of optical forces acting on a spherical particle guided in air with an optical vortex beam, on the light polarization...

Eckerskorn, Niko; Krolikowski, Wieslaw; Shvedov, Vladlen; Rode, Andrei

184

Airfoil Vortex Induced Vibration suppression devices  

E-Print Network (OSTI)

Vortex Induced Vibrations (VIV) is a major concern of the offshore oil industry. This problem leads to fatigue failure in the marine risers and causes costly replacement of the risers. Appendages such as helical strakes ...

Lee, Evan J. (Evan Joseph)

2007-01-01T23:59:59.000Z

185

Holographic Vortex Liquids and Superfluid Turbulence  

Science Journals Connector (OSTI)

...of Kelvin waves flowing along vortex strings in 3D quantum turbulence...theory correlators from non-critical string theory . Phys. Lett. B...S. , Emergence of turbulence in an oscillating Bose-Einstein condensate . Phys. Rev...

Paul M. Chesler; Hong Liu; Allan Adams

2013-07-26T23:59:59.000Z

186

Field-line transport in stochastic magnetic fields: Percolation, Lévy flights, and non-Gaussian dynamics  

Science Journals Connector (OSTI)

The transport of magnetic field lines is studied numerically in the case where strong three-dimensional magnetic fluctuations are superimposed to a uniform average magnetic field. The magnetic percolation of field lines between magnetic islands is found, as well as a non-Gaussian regime where the field lines exhibit Lévy random walks, changing from Lévy flights to trapped motion. Anomalous diffusion laws ??xi2??s? with ?>1 and ?<1 are found for low fluctuation levels, while normal diffusion and Gaussian random walks are recovered for sufficiently high fluctuation levels.

G. Zimbardo and P. Veltri

1995-02-01T23:59:59.000Z

187

Interface boundary conditions for dynamic magnetization and spin wave dynamics in a ferromagnetic layer with the interface Dzyaloshinskii-Moriya interaction  

SciTech Connect

In this work, we derive the interface exchange boundary conditions for the classical linear dynamics of magnetization in ferromagnetic layers with the interface Dzyaloshinskii-Moriya interaction (IDMI). We show that IDMI leads to pinning of dynamic magnetization at the interface. An unusual peculiarity of the IDMI-based pinning is that its scales as the spin-wave wave number. We incorporate these boundary conditions into an existing numerical model for the dynamics of the Damon-Eshbach spin wave in ferromagnetic films. IDMI affects the dispersion and the frequency non-reciprocity of the travelling Damon-Eshbach spin wave. For a broad range of film thicknesses L and wave numbers, the results of the numerical simulations of the spin wave dispersion are in a good agreement with a simple analytical expression, which shows that the contribution of IDMI to the dispersion scales as 1/L, similarly to the effect of other types of interfacial anisotropy. Suggestions to experimentalists how to detect the presence of IDMI in a spin wave experiment are given.

Kostylev, M. [School of Physics, M013, University of Western Australia, Crawley, Perth 6009, Western Australia (Australia)

2014-06-21T23:59:59.000Z

188

Numerical calculation of dynamical friction in electron cooling systems, including magnetic field perturbations and finite time effects  

SciTech Connect

The orders-of-magnitude higher luminosities required by future electron-ion collider concepts require a dissipative force to counteract the numerous factors acting to gradually increase the phase space volume of relativistic ion beams. High-energy electron cooling systems could provide the necessary dissipation via dynamical friction, but will have to be designed for new parameter regimes. It is expected that magnetic field errors, finite interaction time and other effects will reduce the dynamical friction and hence increase the cooling time, so improved understanding of the underlying dynamics is important. We present a generalized form of the classical field-free friction force equation, which conveniently captures some of these effects. Previous work (Bell et al 2008 J. Comput. Phys. 227 8714) shows both numerical and conceptual subtleties associated with undersampling of strong collisions, and we present a rigorous mathematical treatment of such difficulties, based on the use of a modified Pareto distribution for the electron-ion impact parameters. We also present a very efficient numerical algorithm for calculating the dynamical friction on a single ion in the field free case. For the case of arbitrary magnetic field errors, we present numerical simulation results, showing agreement with our generalized friction force formula.

Sobol, A.V.; Fedotov, A.; Bruhwiler, D.L.; Bell, G.I.; Litvinenko, V.

2010-09-24T23:59:59.000Z

189

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

190

Magnetorotational instability, current relaxation, and current-vortex sheet  

SciTech Connect

The conjugate effect of current relaxation and of current-vortex sheet formation on the magnetorotational instability is explored in a conducting fluid. It is found that the relative amplification of the magnetic viscosity from marginal stability to the instability determined by the maximum growth rate is around 924% when resistive effects dominate, while the corresponding quantity is around 220% in the ideal limit. This shows that the conjugate influence is much more efficient to amplify the magnetic viscosity than just the effect due to the standard magnetic tension. It is also found that the magnitude of the magnetic viscosity is effectively enhanced by the conjugate influence. The results presented here may contribute to the understanding of the various processes that play a significant role in the mechanism of anomalous viscosity observed in Keplerian disks. It is argued that the new effect shall be relevant in thin accretion disks. It is also mentioned that the proposed formulation may be of interest for some theories of magnetic reconnection. Possible extensions of this work are suggested.

Silveira, F. E. M. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adélia, 166, CEP 09210-170, Bairro Bangu, Santo André, SP (Brazil)] [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adélia, 166, CEP 09210-170, Bairro Bangu, Santo André, SP (Brazil); Galvão, R. M. O. [Instituto de Física, Universidade de São Paulo, Rua do Matão, Travessa R, 187, CEP 05508-090, Cidade Universitária, São Paulo, SP (Brazil)] [Instituto de Física, Universidade de São Paulo, Rua do Matão, Travessa R, 187, CEP 05508-090, Cidade Universitária, São Paulo, SP (Brazil)

2013-08-15T23:59:59.000Z

191

Reconnection of vortex filaments and Kolmogorov spectrum  

E-Print Network (OSTI)

The energy spectrum of the 3D velocity field, induced by collapsing vortex filaments is studied. One of the aims of this work is to clarify the appearance of the Kolmogorov type energy spectrum $E(k)\\varpropto k^{-5/3}$, observed in many numerical works on discrete vortex tubes (quantized vortex filaments in quantum fluids). Usually, explaining classical turbulent properties of quantum turbulence, the model of vortex bundles, is used. This model is necessary to mimic the vortex stretching, which is responsible for the energy transfer in classical turbulence. In our consideration we do not appeal to the possible "bundle arrangement" but explore alternative idea that the turbulent spectra appear from singular solution, which describe the collapsing line at moments of reconnection. One more aim is related to an important and intensively discussed topic - a role of hydrodynamic collapse in the formation of turbulent spectra. We demonstrated that the specific vortex filament configuration generated the spectrum $E(k)$ close to the Kolmogorov dependence and discussed the reason for this as well as the reason for deviation. We also discuss the obtained results from point of view of the both classical and quantum turbulence.

Sergey K. Nemirovskii

2014-04-19T23:59:59.000Z

192

Calorimetric study of the transitions between the different vortex states in YBa{sub 2}Cu{sub 3}O{sub 7}.  

SciTech Connect

We have studied the vortex phase diagram of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) in very strong magnetic field (0-26 Tesla) by a.c. calorimetry. We describe the anomalies associated with the transitions between the different vortex states (solid, liquid, and glass), with special emphasis on the first order flux lattice melting.

Bouquet, F.; Calemczuk, R.; Crabtree, G. W.; Erb, A.; Fisher, R. A.; Junod, A.; Kwok, W. K.; Marcenat, C.; Phillips, N. E.; Roulin, M.; Schilling, A.; Welp, U.

1999-08-17T23:59:59.000Z

193

Magnetic properties of small multi-layered rings  

E-Print Network (OSTI)

Thin film rings can be an alternative geometry of magnetic memory cells, in which data bits are stored by the chirality of the flux-closed or 'vortex' state of the ring. The absence of the stray field in the vortex state ...

Jung, Wonjoon

2007-01-01T23:59:59.000Z

194

Pseudospin magnetism in graphene  

Science Journals Connector (OSTI)

We predict that neutral graphene bilayers are pseudospin magnets in which the charge density contribution from each valley and spin spontaneously shifts to one of the two layers. The band structure of this system is characterized by a momentum-space vortex, which is responsible for unusual competition between band and kinetic energies, leading to symmetry breaking in the vortex core. We discuss the possibility of realizing a pseudospin version of ferromagnetic metal spintronics in graphene bilayers based on hysteresis associated with this broken symmetry.

Hongki Min; Giovanni Borghi; Marco Polini; A. H. MacDonald

2008-01-17T23:59:59.000Z

195

MAP, MAC, and Vortex-rings Configurations in the Weinberg-Salam Model  

E-Print Network (OSTI)

We report on the presence of new axially symmetric monopoles, antimonopoles and vortex-rings solutions of the SU(2)$\\times$U(1) Weinberg-Salam model of electromagnetic and weak interactions. When the $\\phi$-winding number $n=1$, and 2, the configurations are monopole-antimonopole pair (MAP) and monopole-antimonopole chain (MAC) with poles of alternating sign magnetic charge arranged along the $z$-axis. Vortex-rings start to appear from the MAP and MAC configurations when the winding number $n=3$. The MAP configurations possess zero net magnetic charge whereas the MAC configurations possess net magnetic charge of $4\\pi n/e$. In the MAP configurations, the monopole-antimonopole pair is bounded by the ${\\cal Z}^0$ field flux string and there is an electromagnetic current loop encircling it. The monopole and antimonopole possess magnetic charges $\\pm\\frac{2\\pi n}{e}$ respectively. In the MAC configurations there is no string connecting the monopole and the adjacent antimonopole and they possess magnetic charges $\\pm\\frac{4\\pi n}{e}$ respectively. The MAC configurations possess infinite total energy and zero magnetic dipole moment whereas the MAP configurations which are actually sphalerons possess finite total energy and magnetic dipole moment. The configurations were investigated for varying value of Higgs boson mass $0\\leq M_H^2\\leq 80$ at Weinberg angle $\\theta_W=\\frac{\\pi}{4}$.

Rosy Teh; Ban-Loong Ng; Khai-Ming Wong

2014-08-20T23:59:59.000Z

196

Investigation of the ion dynamics in a multispecies plasma under pulsed magnetic fields  

E-Print Network (OSTI)

of the dissipated magnetic-field energy. The rate of magnetic-field penetration into plasmas is often determined (EMHD)] and experimentally11,12 that the rate of field penetration into non- uniform plasmas can, in which the light-ion plasma (protons) is reflected while the heavy-ion plasma (carbon) is penetrated

197

Improved UTE-based attenuation correction for cranial PET-MR using dynamic magnetic field monitoring  

SciTech Connect

Purpose: Ultrashort echo time (UTE) MRI has been proposed as a way to produce segmented attenuation maps for PET, as it provides contrast between bone, air, and soft tissue. However, UTE sequences require samples to be acquired during rapidly changing gradient fields, which makes the resulting images prone to eddy current artifacts. In this work it is demonstrated that this can lead to misclassification of tissues in segmented attenuation maps (AC maps) and that these effects can be corrected for by measuring the true k-space trajectories using a magnetic field camera. Methods: The k-space trajectories during a dual echo UTE sequence were measured using a dynamic magnetic field camera. UTE images were reconstructed using nominal trajectories and again using the measured trajectories. A numerical phantom was used to demonstrate the effect of reconstructing with incorrect trajectories. Images of an ovine leg phantom were reconstructed and segmented and the resulting attenuation maps were compared to a segmented map derived from a CT scan of the same phantom, using the Dice similarity measure. The feasibility of the proposed method was demonstrated inin vivo cranial imaging in five healthy volunteers. Simulated PET data were generated for one volunteer to show the impact of misclassifications on the PET reconstruction. Results: Images of the numerical phantom exhibited blurring and edge artifacts on the bone–tissue and air–tissue interfaces when nominal k-space trajectories were used, leading to misclassification of soft tissue as bone and misclassification of bone as air. Images of the tissue phantom and thein vivo cranial images exhibited the same artifacts. The artifacts were greatly reduced when the measured trajectories were used. For the tissue phantom, the Dice coefficient for bone in MR relative to CT was 0.616 using the nominal trajectories and 0.814 using the measured trajectories. The Dice coefficients for soft tissue were 0.933 and 0.934 for the nominal and measured cases, respectively. For air the corresponding figures were 0.991 and 0.993. Compared to an unattenuated reference image, the mean error in simulated PET uptake in the brain was 9.16% when AC maps derived from nominal trajectories was used, with errors in the SUV{sub max} for simulated lesions in the range of 7.17%–12.19%. Corresponding figures when AC maps derived from measured trajectories were used were 0.34% (mean error) and ?0.21% to +1.81% (lesions). Conclusions: Eddy current artifacts in UTE imaging can be corrected for by measuring the true k-space trajectories during a calibration scan and using them in subsequent image reconstructions. This improves the accuracy of segmented PET attenuation maps derived from UTE sequences and subsequent PET reconstruction.

Aitken, A. P.; Giese, D.; Tsoumpas, C.; Schleyer, P.; Kozerke, S.; Prieto, C.; Schaeffter, T., E-mail: Tobias.Schaeffter@kcl.ac.uk [Department of Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St. Thomas Hospital, London SE1 7EH (United Kingdom)

2014-01-15T23:59:59.000Z

198

Fabrication and Characterization of Nano-Sized Magnetic Structures and Their Flux-Pinning Effects on Superconducting Thin Films  

E-Print Network (OSTI)

Energy Dissipation due to Vortex Motion .................................. 7 Vortex Pinning in the Ferromagnet-Superconductor Hybrid (FSH) . 9 II FABRICATION OF EMBEDDED FERROMAGNET..., as the external magnetic field increases above the lower critical field and below an upper critical field ??2 (?), the magnetic flux partially penetrates the sample in the form of tubes, or vortices (Fig.4). This state is said to be a vortex state or mixed...

Lee, Han Gil

2011-02-22T23:59:59.000Z

199

Probing nonlinear magnetization dynamics in Fe/MgO(001) film by all optical pump-probe technique  

SciTech Connect

An all-optical pump-probe technique has been employed to investigate the nonlinear magnetization dynamics of a 10?nm Fe/MgO(001) thin film in time domain. The magnetization precession was excited by pump-laser pulses and modulated by laser fluence variations. With increasing the laser fluence up to 7.1 mJ/cm{sup 2}, in addition to the uniform precession mode, a second harmonic signal was detected. The time evolution of the second harmonic signal was obtained in time-frequency domain. Based on the Landau-Lifshitz-Gilbert equation, the numerical simulation was performed to reproduce the observed the frequency doubling behaviors in Fe/MgO(001) film.

He, Wei; Hu, Bo; Zhang, Xiang-Qun; Cheng, Zhao-Hua, E-mail: zhcheng@iphy.ac.cn [State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Zhan, Qing-Feng [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China)

2014-04-07T23:59:59.000Z

200

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

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

Sediment resuspension and erosion by vortex rings  

Science Journals Connector (OSTI)

Particle resuspension and erosion induced by a vortex ringinteracting with a sediment layer was investigated experimentally using flow visualization (particle image velocimetry) high-speed video and a recently developed light attenuation method for measuring displacements in bed level. Near-spherical sediment particles were used throughout with relative densities of 1.2–7 and diameters ( d ) ranging between 90 and 1600 ? ? m . Attention was focused on initially smooth horizontal bedforms with the vortex ring aligned to approach the bed vertically. Interaction characteristics were investigated in terms of the dimensionless Shields parameter defined using the vortex-ring propagation speed. The critical conditions for resuspension (whereby particles are only just resuspended) were determined as a function of particle Reynolds number (based on the particle settling velocity and d ). The effects of viscous damping were found to be significant for d / ? resuspension volumes are analyzed as a function interaction time impact condition and sediment size.

R. J. Munro; N. Bethke; S. B. Dalziel

2009-01-01T23:59:59.000Z

202

Influence of magnetic field on laser-produced barium plasmas: Spectral and dynamic behaviour of neutral and ionic species  

SciTech Connect

The expansion dynamics and spectral behaviour of plasma produced by a Nd:YAG laser (??=?1.064??m, pulse width: 8?ns) from barium target and expanding in 0.45?T transverse magnetic field in vacuum (10{sup ?5?}Torr pressure) are investigated using time-of-flight optical emission spectroscopy. The experiments are carried out at various laser fluences from 12 to 31?J/cm{sup 2}. The temporal profiles of neutral (Ba I 553.5 and 577.7?nm) lines are temporally broadened, while that of ionic (Ba II 413.0 and 455.4?nm) lines show strong confinement in the presence of a magnetic field. In the absence of magnetic field, the temporal profile of Ba I 553.5?nm is exactly reproduced by fitting with two Shifted Maxwell Boltzmann (SMB) Distribution components, while in the presence of a magnetic field the profile could only be fitted with three components. The field enhanced and field induced SMB components of neutral profile are correlated with populations of ground state, metastable states, and long-lived Rydberg states present in the barium plasma, while SMB components of ionic lines are explained on the basis of the presence of super-elastic collisions among the excited species in the plasma. The spatial variation of electron temperature and temporal variation of electron density are deduced and correlated to the different collisional processes in the barium plasma. The ionic profiles show efficient confinement in the presence of a magnetic field at higher fluences.

Raju, Makaraju Srinivasa; Gopinath, Pramod, E-mail: pramod@iist.ac.in [Department of Physics, Indian Institute of Space Science and Technology, Thiruvananthapuram 695547 (India); Singh, R. K.; Kumar, Ajai [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

2014-10-21T23:59:59.000Z

203

PHYSICS OF FLUIDS 24, 125108 (2012) Quantum vortex reconnections  

E-Print Network (OSTI)

is continuous, not discrete, and parts of the initial vortical tubes can be left behind as vortex threads, whichPHYSICS OF FLUIDS 24, 125108 (2012) Quantum vortex reconnections S. Zuccher,1 M. Caliari,1 A. W that the minimum distance between vortices scales differently with time before and after the vortex reconnection

Zuccher, Simone

204

Not All Nanodisk Magnetic Vortices Are Created Equally  

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

T. Sato, S. Kasai, Y. Nakatani, and T. Ono, "Symmetry breaking in the formation of magnetic vortex states in a permalloy nanodisk," Nat. Comm. 3, 983 (2012). ALS Science...

205

Resuspension onset and crater erosion by a vortex ring interacting with a particle layer  

Science Journals Connector (OSTI)

This paper presents results from an experimental investigation of the interaction of a vortex ring with a particle layer. The flowdynamics during the onset of particle resuspension are analysed using particle image velocimetry while a light attenuation method provides accurate measurements of the final eroded crater shape. This work is a continuation of the research described in R. J. Munro N. Bethke and S. B. Dalziel “Sediment resuspension and erosion by vortex rings ” Phys. Fluids21 046601 (2009)10.1063/1.3083318 which focussed on the general resuspension onset dynamics and initial crater formation. Here we analyse the velocity induced by the vortex ring on the particle layer surface during the resuspension of particles for different particle sizes and the shape and size of the final craters that are formed by the impact of the vortex ring. We find that the boundary condition is characterised by a quasi-slip velocity at the particle layer surface independent of the particle size. The particle diameter and thus bed permeability is found to have a significant effect on the final crater characteristics.

N. Bethke; S. B. Dalziel

2012-01-01T23:59:59.000Z

206

Dynamics of rising magnetized cavities and UHECR acceleration in clusters of galaxies  

E-Print Network (OSTI)

We study the expansion of low density cavities produced by Active Galactic Nuclei jets in clusters of galaxies. The long term stability of these cavities requires the presence of linked magnetic fields. We find solutions describing the self-similar expansion of structures containing large-scale electromagnetic fields. Unlike the force-free spheromak-like configurations, these solutions have no surface currents and, thus, are less susceptible to resistive decay. The cavities are internally confined by external pressure, with zero gradient at the surface. If the adiabatic index of the plasma within the cavity is $\\Gamma>4/3$, the expansion ultimately leads to the formation of large-scale current sheets. The resulting dissipation of the magnetic field can only partially offset the adiabatic and radiative losses of radio emitting electrons. We demonstrate that if the formation of large-scale current sheets is accompanied by explosive reconnection of the magnetic field, the resulting reconnection layer can acceler...

Gourgouliatos, Konstantinos N

2011-01-01T23:59:59.000Z

207

Dynamics of ion acoustic double layers in a magnetized two-population electrons plasma  

SciTech Connect

The obliquely propagating ion acoustic (IA) double-layers are investigated in a magnetized two population electron plasmas. The extended Korteweg–de Vries equation is derived by using the reductive perturbation technique. The effect of obliqueness (l{sub z}) and magnitude of the external magnetic field (?{sub ci}), as well as the electron number density (?) on the double-layer profile, is studied, and then the ranges of parameters for which the double-layers exist are investigated in detail. We found that the combined effects of l{sub z}, ?{sub ci}, and ? significantly modify the basic properties (viz. amplitude and width) of the IA double-layers.

Shahmansouri, M. [Department of Physics, Faculty of Science, Arak University, Arak 38156-8-8349 (Iran, Islamic Republic of)] [Department of Physics, Faculty of Science, Arak University, Arak 38156-8-8349 (Iran, Islamic Republic of)

2013-10-15T23:59:59.000Z

208

Jammed vortex matter Hajime Yoshino1  

E-Print Network (OSTI)

. Abstract: Irrationally frustrated Josephson junction array (JJA), namely JJA with irrational number density point. Figure 1: Josephson junction array (JJA) on a square lattice. The vertexes and bonds represent- not develop usual periodic vortex lattices. 1 Introduction Josephson junction array under mag- netic field

Katsumoto, Shingo

209

Vortex Jitter in Hover Swathi M. Mula  

E-Print Network (OSTI)

78712, USA Abstract The trajectory of the tip vortex of a reduced-scale, 1 m diameter, four-bladed rotor condition of the rotor is at a blade loading of CT / = 0.0645 and a rotational speed of 1240RPM wake dominated by the tip vortices shed from the rotor blades. The complexity of the flow

Tinney, Charles E.

210

The multiple vortex nature of tropical cyclogenesis  

E-Print Network (OSTI)

) __________________________ __________________________ John Nielsen-Gammon Craig Epifanio (Chair of Committee) (Member) __________________________ __________________________ Fuqing Zhang Hongxing Liu (Member) (Member) December 2004 Major Subject: Atmospheric Sciences... iii ABSTRACT The Multiple Vortex Nature of Tropical Cyclogenesis. (December 2004) Jason Allen Sippel, B.S., Texas A&M University Chair of Advisory Committee: Dr. John Nielsen-Gammon This thesis contains an observational analysis...

Sippel, Jason Allen

2005-02-17T23:59:59.000Z

211

Quenching Processes in Flame-Vortex Interactions  

E-Print Network (OSTI)

for Astrophysical Thermonuclear Flashes 1 , Chicago, IL 60637 y Department of Astronomy and Astrophysics, University-vortex interactions in order to understand quenching of thermonuclear ames. The key question is|can a ther- monuclear. If a ame encounters a 1) The Center for Astrophysical Thermonuclear Flashes is supported by the Department

Zingale, Michael

212

Quantitative Determination of Chemical Processes by Dynamic Nuclear Polarization Enhanced Nuclear Magnetic Resonance Spectroscopy  

E-Print Network (OSTI)

Dissolution dynamic nuclear polarization (DNP) provides several orders of magnitude of NMR signal enhancement by converting the much larger electron spin polarization to nuclear spin polarization. Polarization occurs at low temperature (1.4K...

Zeng, Haifeng

2012-07-16T23:59:59.000Z

213

Dynamics and waves near multiple magnetic null points in reconnection diffusion region  

E-Print Network (OSTI)

reconnection, a process through which magnetic energy can be converted into kinetic and thermal energy. used the data from the four-spacecraft Cluster constellation to first identify the presence of single observed by the Cluster constellation on 1 October 2001. The topological and physical properties

Ng, Chung-Sang

214

Magnetic Diffusion: Disseminating Mission-Critical Data for Dynamic Sensor Networks  

E-Print Network (OSTI)

of the magnetic field, the sensor data, functioning like the metallic nails, are attracted towards the sink. We-sensing of the room tem- perature allows tuning of the air conditioning to the level just as necessary. Auto, the sensor nodes are likely to run on limited battery power for the ease of deployment. Thus, energy

Huang, Polly

215

Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects  

SciTech Connect

Topics covered are: anomalous transport and E x B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies.

Pankin, Alexei Y.; Kritz, Arnold H.

2011-07-19T23:59:59.000Z

216

Current-Excited Magnetization Dynamics in Narrow Ferromagnetic Wires Yoshihiko TOGAWA1  

E-Print Network (OSTI)

wires is mounted on a special holder for the current application, installed in the column of the 300 kV microscopy. Quantitative distribution of the magnetic flux line is obtained by means of electron holography field-emission transmission electron microscope above the objective lens where the sample is free from

Otani, Yoshichika

217

Neutron Scattering Studies of Vortex Matter in Type-II Superconductors  

SciTech Connect

The proposed program is an experimental study of the fundamental properties of Abrikosov vortex matter in type-II superconductors. Most superconducting materials used in applications such as MRI are type II and their transport properties are determined by the interplay between random pinning, interaction and thermal fluctuation effects in the vortex state. Given the technological importance of these materials, a fundamental understanding of the vortex matter is necessary. The vortex lines in type-II superconductors also form a useful model system for fundamental studies of a number of important issues in condensed matter physics, such as the presence of a symmetry-breaking phase transition in the presence of random pinning. Recent advances in neutron scattering facilities such as the major upgrade of the NIST cold source and the Spallation Neutron Source are providing unprecedented opportunities in addressing some of the longstanding issues in vortex physics. The core component of the proposed program is to use small angle neutron scattering and Bitter decoration experiments to provide the most stringent test of the Bragg glass theory by measuring the structure factor in both the real and reciprocal spaces. The proposed experiments include a neutron reflectometry experiment to measure the precise Q-dependence of the structure factor of the vortex lattice in the Bragg glass state. A second set of SANS experiments will be on a shear-strained Nb single crystal for testing a recently proposed theory of the stability of Bragg glass. The objective is to artificially create a set of parallel grain boundaries into a Nb single crystal and use SANS to measure the vortex matter diffraction pattern as a function of the changing angle between the applied magnetic field to the grain boundaries. The intrinsic merits of the proposed work are a new fundamental understanding of type-II superconductors on which superconducting technology is based, and a firm understanding of phases and phase transitions in condensed matter systems with random pinning. The broader impact of the program includes the training of future generation of neutron scientists, and further development of neutron scattering and complementary techniques for studies of superconducting materials. The graduate and undergraduate students participating in this project will learn the state-of-the-art neutron scattering techniques, acquire a wide range of materials research experiences, and participate in the frontier research of superconductivity. This should best prepare the students for future careers in academia, industry, or government.

Xinsheng Ling

2012-02-02T23:59:59.000Z

218

Nuclear Magnetic Resonance and Nuclear-Spin Dynamics in InP  

Science Journals Connector (OSTI)

Pulsed- and steady-state nuclear-magnetic-resonance measurements are reported for P31 in InP. Measurements on "solid echoes" permit identification of various contributions to the second moment of the resonance. The dominant P31-In115,113 contribution is found to be about a factor of 2 smaller than expected from dipole-dipole interactions alone. A proposed explanation is based on interference between pseudodipolar and dipolar interactions of similar magnitude but opposite sign. The time evolution of the P31 magnetization along the effective field in the rotating frame indicates the presence of a significant cross-relaxation effect involving the resonant spin-Zeeman reservoir and the nonresonant spin-spin reservoir.

M. Engelsberg and R. E. Norberg

1972-05-01T23:59:59.000Z

219

Dynamic high pressure process for fabricating superconducting and permanent magnetic materials  

DOE Patents (OSTI)

Shock wave formation of thin layers of materials with improved superconducting and permanent magnetic properties and improved microstructures is disclosed. The material fabrication system includes a sandwiched structure including a powder material placed between two solid members to enable explosive shock consolidation. The two solid members are precooled to about 80--100 K to reduce the residual temperatures attained as a result of the shock wave treatment, and thereby increase the quench rate of the consolidated powder. 9 figs.

Nellis, W.J.; Geballe, T.H.; Maple, M.B.

1990-03-13T23:59:59.000Z

220

A concept for a magnetic field detector underpinned by the nonlinear dynamics of coupled multiferroic devices  

SciTech Connect

Multiferroic (MF) composites, in which magnetic and ferroelectric orders coexist, represent a very attractive class of materials with promising applications in areas, such as spintronics, memories, and sensors. One of the most important multiferroics is the perovskite phase of bismuth ferrite, which exhibits weak magnetoelectric properties at room temperature; its properties can be enhanced by doping with other elements such as dysprosium. A recent paper has demonstrated that a thin film of Bi{sub 0.7}Dy{sub 0.3}FeO{sub 3} shows good magnetoelectric coupling. In separate work it has been shown that a carefully crafted ring connection of N (N odd and N???3) ferroelectric capacitors yields, past a critical point, nonlinear oscillations that can be exploited for electric (E) field sensing. These two results represent the starting point of our work. In this paper the (electrical) hysteresis, experimentally measured in the MF material Bi{sub 0.7}Dy{sub 0.3}FeO{sub 3}, is characterized with the applied magnetic field (B) taken as a control parameter. This yields a “blueprint” for a magnetic (B) field sensor: a ring-oscillator coupling of N?=?3 Sawyer-Tower circuits each underpinned by a mutliferroic element. In this configuration, the changes induced in the ferroelectric behavior by the external or “target” B-field are quantified, thus providing a pathway for very low power and high sensitivity B-field sensing.

Beninato, A.; Baglio, S.; Andò, B. [Dipartimento di Ingegneria Elettrica Elettronica e dei Sistemi, Università degli Studi di Catania, Viale A. Doria 6, 95125 Catania (Italy)] [Dipartimento di Ingegneria Elettrica Elettronica e dei Sistemi, Università degli Studi di Catania, Viale A. Doria 6, 95125 Catania (Italy); Emery, T.; Bulsara, A. R. [Space and Naval Warfare Systems Center, Code 71000, 53560 Hull Street, San Diego, California 92152-5001 (United States)] [Space and Naval Warfare Systems Center, Code 71000, 53560 Hull Street, San Diego, California 92152-5001 (United States); Jenkins, C. [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd MS6-R2100, Berkeley, California 94720 (United States)] [Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Rd MS6-R2100, Berkeley, California 94720 (United States); Palkar, V. [Center for Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology, Mumbai 400076 (India)] [Center for Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology, Mumbai 400076 (India)

2013-12-09T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

Dynamics of slender monopoles and anti-monopoles in non-Abelian superconductor  

E-Print Network (OSTI)

Low energy dynamics of magnetic monopoles and anti-monopoles in the U(2) gauge theory is studied in the Higgs (non-Abelian superconducting) phase. The monopoles in this superconducting phase are not spherical but are of slender ellipsoid which are pierced by a vortex string. We investigate scattering of the slender monopole and anti-monopole, and find that they do not always decay into radiation, contrary to our naive intuition. They can repel, make bound states (magnetic mesons) or resonances. Analytical solutions including any number of monopoles and anti-monopoles are obtained in the first non-trivial order of rigid-body approximation. We point out that some part of solutions of slender monopole system in 1+3 dimensions can be mapped exactly onto the sine-Gordon system in 1+1 dimensions. This observation allows us to visualize dynamics of monopole and anti-monopole scattering easily.

Masato Arai; Filip Blaschke; Minoru Eto; Norisuke Sakai

2014-07-09T23:59:59.000Z

222

Dynamical instability of white dwarfs and breaking of spherical symmetry under the presence of extreme magnetic fields  

E-Print Network (OSTI)

Massive, highly magnetized white dwarfs with fields up to $10^9$ G have been observed and theoretically used for the description of a variety of astrophysical phenomena. Ultramagnetized white dwarfs with uniform interior fields up to $10^{18}$ G, have been recently purported to obey a new maximum mass limit, $M_{\\rm max}\\approx 2.58~M_\\odot$, which largely overcomes the traditional Chandrasekhar value, $M_{\\rm Ch}\\approx 1.44~M_\\odot$. Such a much larger limit would make these astrophysical objects viable candidates for the explanation of the superluminous population of type Ia supernovae. We show that several macro and micro physical aspects such as gravitational, dynamical stability, breaking of spherical symmetry, general relativity, inverse $\\beta$-decay, and pycnonuclear fusion reactions are of most relevance for the self-consistent description of the structure and assessment of stability of these objects. It is shown in this work that the first family of magnetized white dwarfs indeed satisfy all the criteria of stability, while the ultramagnetized white dwarfs are very unlikely to exist in nature since they violate minimal requests of stability. Therefore, the canonical Chandrasekhar mass limit of white dwarfs has to be still applied.

J. G. Coelho; R. M. Marinho; M. Malheiro; R. Negreiros; D. L. Cáceres; J. A. Rueda; R. Ruffini

2014-09-26T23:59:59.000Z

223

Ultrafast Magnetization Dynamics of SrRuO3 Thin Films  

SciTech Connect

Itinerant ferromagnet SrRuO3 has drawn interest from physicists due to its unusual transport and magnetic properties as well as from engineers due to its low resistivity and good lattice-matching to other oxide materials. The exact electronic structure remains a mystery, as well as details of the interactions between magnetic and electron transport properties. This thesis describes the use of time-resolved magneto-optical Kerr spectroscopy to study the ferromagnetic resonance of SrRuO3 thin films, where the ferromagnetic resonance is initiated by a sudden change in the easy axis direction in response to a pump pulse. The rotation of the easy axis is induced by laser heating, taking advantage of a temperature-dependent easy axis direction in SrRuO3 thin films. By measuring the change in temperature of the magnetic system in response to the laser pulse, we find that the specific heat is dominated by magnons up to unusually high temperature, ~;;100 K, and thermal diffusion is limited by a boundary resistance between the film and the substrate that is not consistent with standard phonon reflection and scattering models. We observe a high FMR frequency, 250 GHz, and large Gilbert damping parameter, alpha ~;; 1, consistent with strong spin-orbit coupling. We observe a time-dependent change in the easy axis direction on a ps time-scale, and we find that parameters associated with the change in easy axis, as well as the damping parameter, have a non-monotonic temperature dependence similar to that observed in anomalous Hall measurements.

Langner, Matthew C

2009-05-19T23:59:59.000Z

224

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)

225

Nuclear magnetic resonance investigation of dynamics in poly(ethylene oxide)-based lithium polyether-ester-sulfonate ionomers  

Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies for motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.

Roach, David J. [Pennsylvania State University, University Park, PA (United States); Dou, Shichen [Pennsylvania State University, University Park, PA (United States); Colby, Ralph H. [Pennsylvania State University, University Park, PA (United States); Mueller, Karl T. [Pacific Northwest Lab., Richland, WA (United States)

2012-01-06T23:59:59.000Z

226

Contour dynamics, waves, and solitons in the quantum Hall effect  

Science Journals Connector (OSTI)

We present a theoretical study of the excitations on the edge of a two-dimensional electron system in a perpendicular magnetic field in terms of a contour dynamics formalism. In particular, we focus on edge excitations in the quantum Hall effect. Beyond the usual linear approximation, a nonlinear analysis of the shape deformations of an incompressible droplet yields soliton solutions which correspond to shapes that propagate without distortion. A perturbative analysis is used and the results are compared to analogous systems, like vortex patches in ideal hydrodynamics. Under a local induction approximation, we find that the contour dynamics is described by a nonlinear partial differential equation for the curvature: the modified Korteweg–de Vries equation.

C. Wexler and Alan T. Dorsey

1999-10-15T23:59:59.000Z

227

Temperature dependence of vortex charges in high-temperature superconductors  

Science Journals Connector (OSTI)

Using a model Hamiltonian with d-wave superconductivity and competing antiferromagnetic (AF) interactions, the temperature (T) dependence of the vortex charge in high-Tc superconductors is investigated by numerically solving the Bogoliubov–de Gennes equations. The strength of the induced AF order inside the vortex core is T dependent. The vortex charge could be negative when the AF order with sufficient strength is present at low temperatures. At higher temperatures, the AF order may be completely suppressed and the vortex charge becomes positive. A first-order-like transition in the T-dependent vortex charge is seen near the critical temperature TAF. For an underdoped sample, the spatial profiles of the induced spin-density wave and the charge-density wave orders could have stripelike structures at TTs. As a result, a vortex charge discontinuity occurs at Ts.

Yan Chen; Z. D. Wang; C. S. Ting

2003-06-03T23:59:59.000Z

228

Effect of Field Errors in Muon Collider IR Magnets on Beam Dynamics  

SciTech Connect

In order to achieve peak luminosity of a Muon Collider (MC) in the 10{sup 35} cm{sup -2}s{sup -1} range very small values of beta-function at the interaction point (IP) are necessary ({beta}* {le} 1 cm) while the distance from IP to the first quadrupole can not be made shorter than {approx}6 m as dictated by the necessity of detector protection from backgrounds. In the result the beta-function at the final focus quadrupoles can reach 100 km making beam dynamics very sensitive to all kind of errors. In the present report we consider the effects on momentum acceptance and dynamic aperture of multipole field errors in the body of IR dipoles as well as of fringe-fields in both dipoles and quadrupoles in the ase of 1.5 TeV (c.o.m.) MC. Analysis shows these effects to be strong but correctable with dedicated multipole correctors.

Alexahin, Y.; Gianfelice-Wendt, E.; Kapin, V.V.; /Fermilab

2012-05-01T23:59:59.000Z

229

Acceleration and vortex filaments in turbulence  

E-Print Network (OSTI)

We report recent results from a high resolution numerical study of fluid particles transported by a fully developed turbulent flow. Single particle trajectories were followed for a time range spanning more than three decades, from less than a tenth of the Kolmogorov time-scale up to one large-eddy turnover time. We present some results concerning acceleration statistics and the statistics of trapping by vortex filaments.

F. Toschi; L. Biferale; G. Boffetta; A. Celani; B. J. Devenish; A. Lanotte

2005-01-23T23:59:59.000Z

230

Jet?vortex Interaction: A Numerical Study  

Science Journals Connector (OSTI)

The interaction of a vortex and a jet plays an important role for many industrial processes such as Carbon Black formation or combustion in diesel engines. The knowledge of physics of these phenomena is crucial for engineers but also for scientists who wish to reveal many interesting and complex issues hidden there. In this research we numerically investigate cases where a cylindrical reactor is charged with gas injected through five ports. The first one is located along the main axis of the cylinder and this leads to the formation of the main jet. The other four ports are situated along the side walls such that the gas entering the cylinder tangentially through them causes a vortex to be formed. The objective of this paper is to show the fundamental physical phenomena and also how the initial and boundary conditions influence the results. Our most important observation at this stage is that the mixing process is more intense if the vortex is inclined towards x?axis. The results are mainly shown as snapshots of gas velocity.

Catalin G. Ilea; Pawel Kosinski; Alex C. Hoffmann

2009-01-01T23:59:59.000Z

231

Magnetic and dynamical photospheric disturbances observed during an M3.2 solar flare  

E-Print Network (OSTI)

This letter reports on a set of full-Stokes spectropolarimetric observations in the near infrared He I 10830 A spectral region covering the pre-, flare, and post-flare phases of an M3.2 class solar flare. The flare originated on 2013 May 17 and belonged to active region NOAA 11748. We detected strong He I 10830 A emission in the flare. The red component of the He I triplet peaks at an intensity ratio to the continuum of about 1.86. During the flare, He I Stokes V is substantially larger and appears reversed compared to the usually larger Si I Stokes V profile. The photospheric Si I inversions of the four Stokes profiles reveal the following: (1) the magnetic field strength in the photosphere decreases or is even absent during the flare phase, as compared to the pre-flare phase. However, this decrease is not permanent. After the flare the magnetic field recovers its pre-flare configuration in a short time (i.e., in 30 minutes after the flare). (2) In the photosphere, the line-of-sight velocities show a regular...

Kuckein, C; Sainz, R Manso

2015-01-01T23:59:59.000Z

232

Novel Vortex Generator and Mode Converter for Electron Beams  

Science Journals Connector (OSTI)

A mode converter for electron vortex beams is described. Numerical simulations, confirmed by experiment, show that the converter transforms a vortex beam with a topological charge m=±1 into beams closely resembling Hermite-Gaussian HG10 and HG01 modes. The converter can be used as a mode discriminator or filter for electron vortex beams. Combining the converter with a phase plate turns a plane wave into modes with topological charge m=±1. This combination serves as a generator of electron vortex beams of high brilliance.

P. Schattschneider; M. Stöger-Pollach; J. Verbeeck

2012-08-22T23:59:59.000Z

233

Energy Separation And Lox Separation Studies In Vortex Tubes.  

E-Print Network (OSTI)

??Vortex Tube (VT) is a simple device having no moving mechanical parts, in which compressed gas at high pressure is injected through one or more… (more)

Behera, Upendra

2011-01-01T23:59:59.000Z

234

Magnetic-field variance in layered superconductors  

Science Journals Connector (OSTI)

In highly anisotropic or layered high-Tc superconductors with magnetic field along the c axis, both pinning-caused and thermal fluctuations of the highly flexible vortex cores, or of chains of vortex dots, threading the cuperconducting layers may drastically reduce the variance ? of the magnetic-field fluctuation. In contrast, the fluctuations of the averaged flux lines (smoothed over the in-plane penetration depth ?) increase ?. As a consequence, muon-spin-rotation lines may be sharpened not only the thermal motional narrowing, but also by pinning-caused static disorder.

Ernst Helmut Brandt

1991-06-17T23:59:59.000Z

235

Vortex motion rectification in Josephson junction arrays with a ratchet potential  

E-Print Network (OSTI)

By means of electrical transport measurements we have studied the rectified motion of vortices in ratchet potentials engineered on over-damped Josephson junction arrays. The rectified voltage as a function of the vortex density shows a maximum efficiency close a matching condition to the period of the ratchet potential indicating a collective vortex motion. Vortex current reversals where detected varying the driving force and vortex density revealing the influence of vortex-vortex interaction in the ratchet effect.

D. E. Shalom; H. Pastoriza

2004-11-19T23:59:59.000Z

236

An application of vortex cancellation to vortex generator techniques in low speed wind tunnels  

E-Print Network (OSTI)

'lugs/ft-sec Axial distance between sets of vortex generators root chord lengths /Y Vertical dimension of duct cross section Tube height/Y in. none ~St i t ()i ()2 (), ( )?q Measured at station g 1 Measured at Station 0 8 Upstream srl... TABLE I II BOUNDARY LAYER PROFILE DATA IN THE VICINITY OF A VORTEX FILAMENT AT STATION 0 7 Tube Number I 2 3 4. 5 6 7 8 9 '10 I 2 3 4 5 6 7 8 9 10 I 2 3 4 5 6 7 8 9 10 Ft-Fs in. H 0 1. 31 1. 31 1. 31 I . 26 1. 20...

Mount, Glynn O., Jr

2012-06-07T23:59:59.000Z

237

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

238

E-Print Network 3.0 - advanced vortex element Sample Search Results  

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

method of plasma Summary: with the new simple explanation of the energy separation in vortex tubes described here. Advanced numerical... vortex method of plasma insulation and...

239

E-Print Network 3.0 - accelerated vortex ring Sample Search Results  

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

left behind... forces were derived from the vortex rings, assuming all propulsive energy to be compiled in the rings... , ending up in a separate vortex ... Source:...

240

Transverse energy circulation and the edge diffraction of an optical vortex beam  

Science Journals Connector (OSTI)

Edge diffraction of a circular Laguerre–Gaussian beam represents an example of the optical vortex symmetry breakdown in which the hidden “vortex” energy...

Bekshaev, Aleksandr Ya; Mohammed, Kadhim A; Kurka, Ivan A

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

Polaron-like vortices, dissociation transition, and self-induced pinning in magnetic superconductors  

SciTech Connect

Vortices in magnetic superconductors polarize spins nonuniformly and repolarize them when moving. At a low spin relaxation rate and at low bias currents, vortices carrying magnetic polarization clouds become polaron-like and their velocities are determined by the effective drag coefficient that is significantly bigger than the Bardeen-Stephen (BS) one. As the current increases, vortices release polarization clouds and the velocity as well as the voltage in the I-V characteristics jump to values corresponding to the BS drag coefficient at a critical current J{sub c}. The nonuniform components of the magnetic field and magnetization drop as the velocity increases, resulting in weaker polarization and a discontinuous dynamic dissociation depinning transition. Experimentally, the jump shows up as a depinning transition and the corresponding current at the jump is the depinning current. As the current decreases, on the way back, vortices are retrapped by polarization clouds at the current J{sub r} < J{sub c}. As a result, the polaronic effect suppresses dissipation and enhances the critical current. Borocarbides (RE)Ni{sub 2}B{sub 2}C with a short penetration length and highly polarizable rare earth spins seem to be optimal systems for a detailed study of vortex polaron formation by measuring I-V characteristics. We also propose to use a superconductor-magnet multilayer structure to study polaronic mechanism of pinning with the goal to achieve high critical currents. The magnetic layers should have large magnetic susceptibility to enhance the coupling between vortices and magnetization in magnetic layers while the relaxation of the magnetization should be slow. For Nb and a proper magnet multilayer structure, we estimate the critical current density J{sub c} {approx} 10{sup 9} A/m{sup 2} at the magnetic field B Almost-Equal-To 1 T.

Bulaevskii, L. N., E-mail: lnb@lanl.gov; Lin, S.-Z. [Los Alamos National Laboratory, Theoretical Division (United States)] [Los Alamos National Laboratory, Theoretical Division (United States)

2013-09-15T23:59:59.000Z

242

STATIC AND DYNAMIC MEASUREMENTS OF A PERMANENT MAGNET INDUCTION GENERATOR: TEST RESULTS OF A NEW WIND GENERATOR CONCEPT  

Science Journals Connector (OSTI)

The Permanent Magnet Induction Machine, a new wind generator concept, is considered to be a highly...

Gabriele Gail; Thomas Hartkopf…

2006-01-01T23:59:59.000Z

243

Mechanical (acoustic?like) wave propagation along a vortex array in the superconducting heterostructure  

Science Journals Connector (OSTI)

Magnetic flux can penetrate the type ? II superconductor in the form of Abrikosov vortices (also called flux lines flux tubes or fluxons) each carrying a quantum of magnetic flux. These tiny vortices of supercurrent tend to arrange themselves in a triangular or quadratic flux?line lattice. Since the vortices are formed by the applied magnetic field around of each of them the supercurrent flows. Moreover there also exist some Lorentz force interactions among them. Those interactions form an origin of an additional mechanical (stress) field occurring in the type?II superconductor. The paper deals with an analysis of elastic (acoustic?like) wave propagation solely along vortices in a heterostructure consisted of the superconducting layer put on the superconducting substrate. Dispersion and the amplitude distribution of those waves in the vortex field existing in that structure has been presented.

Bogdan T. Maruszewski; Andrzej Drzewiecki; Roman Starosta

2008-01-01T23:59:59.000Z

244

Optical excitation of quasiparticle pairs in the vortex core of high- T sub c superconductors  

SciTech Connect

A far-infrared resonance has been observed in superconducting YBa{sub 2}Cu{sub 3}O{sub 7} thin films in the presence of high magnetic fields. It corresponds to the quasiparticle pair creation process inside the vortex core. The resonance frequency is {omega}{sub 0}=1.3{ital kT}{sub {ital c}}/{h bar} with a linewidth 1/{tau}{congruent}0.6{omega}. This value for {omega}{sub 0} implies, within BCS theory, a large energy gap in YBa{sub 2}Cu{sub 3}O{sub 7}.

Karraie, K.; Choi, E.J.; Dunmore, F.; Liu, S.H.; Drew, H.D. (Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, Maryland 20742 (United States) Laboratory for Physical Sciences, College Park, Maryland 20740 (United States)); Li, Q.; Fenner, D.B. (Advanced Fuel Research, E. Hartford, Connecticut 06138 (United States)); Zhu, Y.D.; Zhang, F. (Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221 (United States))

1992-07-06T23:59:59.000Z

245

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

246

ENERGY LEVEL SPECTROSCOPY OF A BOUND VORTEX-ANTIVORTEX PAIR  

E-Print Network (OSTI)

vortex- antivortex (VAV) state in an annular Josephson junction. The bound VAV pair is formed microwave spectroscopy. Keywords: Macroscopic quantum effects, long Josephson junctions, vortex­9]. Most of the studied systems, such as dc-biased Josephson junctions (JJ), supercon- ducting quantum

Wallraff, Andreas

247

The Impact of Cold Dark Matter Variants on the Halos of the First Stars and Galaxies: Angular Momentum and Vortex Creation in BEC Dark Matter  

SciTech Connect

If cold dark matter elementary particles form a Bose-Einstein condensate, their superfluidity may distinguish them from other forms of cold dark matter, including the creation of quantum vortices. We have shown that such vortices are favored in strongly-coupled condensates. Vortex creation causes central densities to drop, thus affecting the dynamics of the gaseous baryonic component and subsequently star formation.

Rindler-Daller, Tanja [Department of Astronomy and Texas Cosmology Center, University of Texas at Austin (United States); Institut fuer Theoretische Physik, Universitaet zu Koeln, Cologne (Germany); Shapiro, Paul R. [Department of Astronomy and Texas Cosmology Center, University of Texas at Austin (United States)

2010-11-03T23:59:59.000Z

248

Quantum Hasimoto transformation and nonlinear waves on a superfluid vortex filament under the quantum local induction approximation  

E-Print Network (OSTI)

The Hasimoto transformation between the classical LIA (local induction approximation, a model approximating the motion of a thin vortex filament) and the nonlinear Schr\\"odinger equation (NLS) has proven very useful in the past, since it allows one to construct new solutions to the LIA once a solution to the NLS is known. In the present paper, the quantum form of the LIA (which includes mutual friction effects) is put into correspondence with a type of complex nonlinear dispersive partial differential equation (PDE) with cubic nonlinearity (similar in form to a Ginsburg-Landau equation, with additional nonlinear terms). Transforming the quantum LIA in such a way enables one to obtain quantum vortex filament solutions once solutions to this dispersive PDE are known. From our quantum Hasimoto transformation, we determine the form and behavior of Stokes waves and a standing 1-soliton solution under normal and binormal friction effects. The soliton solution on a quantum vortex filament is a natural generalization of the classical 1-soliton solution constructed mathematically by Hasimoto (which motivated subsequent real-world experiments). The quantum Hasimoto transformation is useful when normal fluid velocity is relatively weak, so for the case where the normal fluid velocity is dominant we resort to other approaches. We consider the dynamics of the tangent vector to the vortex filament directly from the quantum LIA, and this approach, while less elegant than the quantum Hasimoto transformation, enables us to study waves primarily driven by the normal fluid velocity.

Robert A. Van Gorder

2014-11-19T23:59:59.000Z

249

Irreversible flow of vortex matter: Polycrystal and amorphous phases Paolo Moretti and M.-Carmen Miguel  

E-Print Network (OSTI)

systems exhibiting this phenomenol- ogy, flux line vortex lattices in type II superconductors rep- resent

Miguel-Lopez, Carmen

250

Potential Flow Model of a Vortex Street Near a Fish-like Body  

E-Print Network (OSTI)

Potential Flow Model of a Vortex Street Near a Fish-like Body Joshua Brulé, University of Maryland to inviscid, irrotational solutions of Navier-Stokes · Vortex potential: "A model of the lateral line of fish for vortex sensing." Ren Z, Mohseni K. 2012 #12;Vortex near a (circular) fish · (Insert your own spherical

Anlage, Steven

251

Spin Torques in Magnetic and Superconducting Tunnel Junctions  

E-Print Network (OSTI)

Josephson Junctions . . . . . . . . . . . . . . . . . . . . .Nonlinear Dynamics in a Magnetic Josephson Junction . . . .in a magnetic Josephson junction. ” Phys. Rev. B, 86:

Hoffman, Silas Eli

2012-01-01T23:59:59.000Z

252

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.

253

Using Realistic MHD Simulations for Modeling and Interpretation of Quiet-Sun Observations with the Solar Dynamics Observatory Helioseismic and Magnetic Imager  

E-Print Network (OSTI)

The solar atmosphere is extremely dynamic, and many important phenomena develop on small scales that are unresolved in observations with the Helioseismic and Magnetic Imager (HMI) instrument on the Solar Dynamics Observatory (SDO). For correct calibration and interpretation, it is very important to investigate the effects of small-scale structures and dynamics on the HMI observables, such as Doppler shift, continuum intensity, spectral line depth, and width. We use 3D radiative hydrodynamics simulations of the upper turbulent convective layer and the atmosphere of the Sun, and a spectro-polarimetric radiative transfer code to study observational characteristics of the Fe I 6173A line observed by HMI in quiet-Sun regions. We use the modeling results to investigate the sensitivity of the line Doppler shift to plasma velocity, and also sensitivities of the line parameters to plasma temperature and density, and determine effective line formation heights for observations of solar regions located at different dista...

Kitiashvili, Irina N; Lagg, Andreas

2014-01-01T23:59:59.000Z

254

Dynamic  

Office of Legacy Management (LM)

Dynamic Dynamic , and Static , Res.ponse of the Government Oil Shale Mine at ' , . , Rifle, Colorado, to the Rulison Event. , . ; . . DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. p ( y c - - a 2-1 0 -4- REPORT AT (29-2) 914 USBM 1 0 0 1 UNITED STATES DEPARTMENT O F THE I NTERIOR BUREAU OF MINES e s.09 P. L. R U S S E L L RESEARCH D l RECTOR Februory 2, lB7O DYNAMIC AND STATIC RESPONSE 'OF THE GOVERNMENT OIL SHALE MINE A T RIFLE, COLORADO, T O THE, RULISON EVENT ORDER FROM CFSTl A S ~ B ~ &J C / This page intentionally left blank CONTENTS Page . . . . . . . . . . . . . . . . . . . . . . . . . H i s t o r i c . a l Des c r i p t i o n 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Summary 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction 3

255

Vortex configurations of bosons in an optical lattice  

SciTech Connect

The single-vortex problem in a strongly correlated bosonic system is investigated self-consistently within the mean-field theory of the Bose-Hubbard model. Near the superfluid-Mott-insulator transition, the vortex core has a tendency toward the Mott-insulating phase, with the core particle density approaching the nearest commensurate value. If the nearest-neighbor repulsion exists, the charge-density wave order may develop locally in the core. The evolution of the vortex configuration from the strong- to weak-coupling regions is studied. This phenomenon can be observed in systems of rotating ultracold atoms in optical lattices and Josephson-junction arrays.

Wu Congjun; Zhang Shoucheng [Department of Physics, McCullough Building, Stanford University, Stanford, California 94305-4045 (United States); Chen Handong [Department of Applied Physics, McCullough Building, Stanford University, Stanford, California 94305-4045 (United States); Hu Jiangpiang [Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547 (United States)

2004-04-01T23:59:59.000Z

256

Integrated multi vector vortex beam generator  

E-Print Network (OSTI)

A novel method to generate and manipulate vector vortex beams in an integrated, ring resonator based geometry is proposed. We show numerically that a ring resonator, with an appropriate grating, addressed by a vertically displaced access waveguide emits a complex optical field. The emitted beam possesses a specific polarization topology, and consequently a transverse intensity profile and orbital angular momentum. We propose a combination of several concentric ring resonators, addressed with different bus guides, to generate arbitrary orbital angular momentum qudit states, which could potentially be used for classical and quantum communications. Finally, we demonstrate numerically that this device works as an orbital angular momentum sorter with an average cross-talk of -10 dB between different orbital angular momentum channels.

Sebastian A. Schulz; Taras Machula; Ebrahim Karimi; Robert W. Boyd

2013-03-19T23:59:59.000Z

257

A study on passive methods of vortex induced vibrations suppression  

E-Print Network (OSTI)

A number of engineering systems, including those found in offshore operations, are often affected by vortex-induced vibrations (VIV). This phenomenon is caused by the interaction between a structure and shed vortices which ...

Galvao, Richardo A

2008-01-01T23:59:59.000Z

258

Experimental demonstration of vortex pancake in high temperature superconductor  

Science Journals Connector (OSTI)

In order to demonstrate the existence of the vortex pancake in high temperature superconductor experimentally, a configuration in which the current...E-j relation obtained with this electrodes spatial configurati...

Wei-xian Wang; Yu-heng Zhang

2006-09-01T23:59:59.000Z

259

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

260

Dynamics  

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

Hydration Hydration Water on Rutile Studied by Backscattering Neutron Spectroscopy and Molecular Dynamics Simulation E. Mamontov,* ,† D. J. Wesolowski, ‡ L. Vlcek, § P. T. Cummings, §,| J. Rosenqvist, ‡ W. Wang, ⊥ and D. R. Cole ‡ Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6473, Chemical Sciences DiVision, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6110, Department of Chemical Engineering, Vanderbilt UniVersity, NashVille, Tennessee 37235-1604, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6496, and EnVironmental Sciences DiVision, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6036 ReceiVed: December 20, 2007; ReVised Manuscript ReceiVed: June 4, 2008 The high energy resolution, coupled with the wide dynamic range, of the new backscattering

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261

Investigating the Structural Dynamics of 1,4-Galactosyltransferase C from Neisseria meningitidis by Nuclear Magnetic Resonance  

E-Print Network (OSTI)

by Nuclear Magnetic Resonance Spectroscopy Patrick H. W. Chan,, Adrienne H. Cheung, Mark Okon,,§ Hong mobility. Accordingly, we have used nuclear magnetic resonance spectroscopy to probe the structural, and only the "b" state is competent for substrate binding. For both states, relaxation dispersion studies

McIntosh, Lawrence P.

262

WAVE-VORTEX MODE COUPLING IN ASTROPHYSICAL ACCRETION DISKS UNDER COMBINED RADIAL AND VERTICAL STRATIFICATION  

SciTech Connect

We examine accretion disk flow under combined radial and vertical stratification utilizing a local Cartesian (or ''shearing box'') approximation. We investigate both axisymmetric and nonaxisymmetric disturbances with the Boussinesq approximation. Under axisymmetric disturbances, a new dispersion relation is derived. It reduces to the Solberg-Hoieland criterion in the case without vertical stratification. It shows that, asymptotically, stable radial and vertical stratification cannot induce any linear instability; Keplerian flow is accordingly stable. Previous investigations strongly suggest that the so-called bypass concept of turbulence (i.e., that fine-tuned disturbances of any inviscid smooth shear flow can reach arbitrarily large transient growth) can also be applied to Keplerian disks. We present an analysis of this process for three-dimensional plane-wave disturbances comoving with the shear flow of a general rotating shear flow under combined stable radial and vertical rotation. We demonstrate that large transient growth occurs for K{sub 2}/k{sub 1} >> 1 and k{sub 3} = 0 or k{sub 1} {approx} k{sub 3}, where k{sub 1}, K{sub 2}, and k{sub 3} are the azimuthal, radial, and vertical components of the initial wave vector, respectively. By using a generalized ''wave-vortex'' decomposition of the disturbance, we show that the large transient energy growth in a Keplerian disk is mainly generated by the transient dynamics of the vortex mode. The analysis of the power spectrum of total (kinetic+potential) energy in the azimuthal or vertical directions shows that the contribution coming from the vortex mode is dominant at large scales, while the contribution coming from the wave mode is important at small scales. These findings may be confirmed by appropriate numerical simulations in the high Reynolds number regime.

Salhi, A. [Departement de Physique, Faculte des Sciences de Tunis, 1060 Tunis (Tunisia); Lehner, T. [LUTH, UMR 8102 CNRS, Observatoire de Paris-Meudon, 5 place de Janssen, F-92195 Meudon (France); Godeferd, F.; Cambon, C. [Laboratoire de Mecanique des Fluides et d'Acoustique, Ecole Centrale de Lyon, Universite de Lyon, UMR 5509, CNRS, INSA, UCB, F-69134 Ecully Cedex (France)

2013-07-10T23:59:59.000Z

263

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

264

Dynamic roughening of directed lines  

Science Journals Connector (OSTI)

We study the fluctuations of a stretched string, e.g., a vortex line, moving in a random medium. A pair of nonlinear equations are proposed to describe the evolution of longitudinal and transverse coordinates. The dynamic scaling of the fluctuations is studied analytically (by renormalization group) and numerically. In most cases the fluctuations are superdiffusive, governed by a dynamic exponent z=3/2.

Deniz Erta? and Mehran Kardar

1992-08-10T23:59:59.000Z

265

Effective world-sheet theory of color magnetic flux tubes in dense QCD  

SciTech Connect

Color magnetic flux tubes appear in the color-flavor locked phase of high density QCD, which exhibits color superconductivity as well as superfluidity. They are non-Abelian superfluid vortices and are accompanied by orientational zero modes in the internal space associated with the color-flavor locked symmetry spontaneously broken in the presence of the vortex. We show that those zero modes are localized around the vortex in spite of the logarithmic divergence of its tension and derive the low-energy effective theory of them on the world sheet of the vortex string.

Eto, Minoru [Theoretical Physics Laboratory, RIKEN, Saitama 351-0198 (Japan); Nakano, Eiji [Extreme Matter Institute, GSI, Planckstrasse 1, D-64291 Darmstadt (Germany); Nitta, Muneto [Department of Physics, and Research and Education Center for Natural Sciences, Keio University, 4-1-1 Hiyoshi, Yokohama, Kanagawa 223-8521 (Japan)

2009-12-15T23:59:59.000Z

266

Color Magnetic Flux Tubes in Dense QCD. II: Effective World-Sheet Theory  

E-Print Network (OSTI)

Color magnetic flux tubes appear in the color-flavor locked phase of high density QCD, which exhibits color superconductivity as well as superfluidity. They are non-Abelian superfluid vortices and are accompanied by orientational zero modes in the internal space associated with the color-flavor locked symmetry spontaneously broken in the presence of the vortex. We show that those zero modes are localized around the vortex in spite of the logarithmic divergence of its tension, and derive the low-energy effective theory of them on the world-sheet of the vortex-string.

Minoru Eto; Eiji Nakano; Muneto Nitta

2009-08-31T23:59:59.000Z

267

Color Magnetic Flux Tubes in Dense QCD. II: Effective World-Sheet Theory  

E-Print Network (OSTI)

Color magnetic flux tubes appear in the color-flavor locked phase of high density QCD, which exhibits color superconductivity as well as superfluidity. They are non-Abelian superfluid vortices and are accompanied by orientational zero modes in the internal space associated with the color-flavor locked symmetry spontaneously broken in the presence of the vortex. We show that those zero modes are localized around the vortex in spite of the logarithmic divergence of its tension, and derive the low-energy effective theory of them on the world-sheet of the vortex-string.

Eto, Minoru; Nitta, Muneto

2009-01-01T23:59:59.000Z

268

Experimental Investigations of Vortex Induced Vibration of A Flat Plate in Pitch Oscillation  

E-Print Network (OSTI)

A bluff structure placed in a flowing fluid, may be subjected to vortex-induced vibrations (VIV). For a flat plate with only rotational degree of freedom, the VIV is rotational oscillation. Based on the experimental investigation, vortex...

Yang, Yi

2012-02-14T23:59:59.000Z

269

Generation and Propagation of Inertia Gravity Waves from Vortex Dipoles and Jets Shuguang Wang  

E-Print Network (OSTI)

Generation and Propagation of Inertia Gravity Waves from Vortex Dipoles and Jets Shuguang Wang generation and propagation from jets within idealized vortex dipoles using a nonhydrostatic mesoscale model, moist convection, fronts, upper level jets, geostrophic adjustment and spontaneous generation (Fritts

270

Self-Consistent Electronic Structure of a dx2-y2 and a dx2-y2 + idxy Vortex  

Science Journals Connector (OSTI)

We investigate quasiparticle states associated with an isolated vortex in a d-wave superconductor using a self-consistent Bogoliubov–de Gennes formalism. For a pure dx2-y2 superconductor we find that there exist no bound states in the core; all the states are extended with continuous energy spectrum. This result is inconsistent with the existing experimental data on cuprates. We propose an explanation for this data in terms of a magnetic-field-induced dx2-y2+idxy state recently invoked in connection with the thermal conductivity measurements on Bi2Sr2CaCu2O8.

M. Franz and Z. Tešanovi?

1998-05-25T23:59:59.000Z

271

Dynamics of positive probes in underdense, strongly magnetized, E×B drifting plasma: Particle-in-cell simulations  

SciTech Connect

Electron trapping, electron heating, space-charge wings, wake eddies, and current collection by a positive probe in E×B drifting plasma were studied in three-dimensional electromagnetic particle-in-cell simulations. In these simulations, electrons and ions were magnetized with respect to the probe and the plasma was underdense (?{sub pe}magnetic fields. Four distinct regions developed in the presences of the positive probe: a quasi-trapped electron region, an electron-depletion wing, an ion-rich wing, and a wake region. We report on the observations of strong electron heating mechanisms, space-charge wings, ion cyclotron charge-density eddies in the wake, electron acceleration due to a magnetic presheath, and the current-voltage relationship.

Heinrich, Jonathon R.; Cooke, David L. [Air Force Research Laboratory, Kirtland Air Force Base, New Mexico 87117 (United States)] [Air Force Research Laboratory, Kirtland Air Force Base, New Mexico 87117 (United States)

2013-09-15T23:59:59.000Z

272

Superconducting strip in an oblique magnetic field  

Science Journals Connector (OSTI)

As an example for a seemingly simple but actually intricate problem, we study the Bean critical state in a superconducting strip of finite thickness d and width 2w?d placed in an oblique magnetic field. The analytical solution is obtained to leading order in the small parameter d?w. The critical state depends on how the applied magnetic field is switched on, e.g., at a constant tilt angle, or first the perpendicular and then the parallel field component. For these two basic scenarios we obtain the distributions of current density and magnetic field in the critical states. In particular, we find the shapes of the flux-free core and of the lines separating regions with opposite direction of the critical currents, the detailed magnetic field lines (along the vortex lines), and both components of the magnetic moment. The component of the magnetic moment parallel to the strip plane is a nonmonotonic function of the applied magnetic field.

G. P. Mikitik; E. H. Brandt; M. Indenbom

2004-07-30T23:59:59.000Z

273

Mutual Chern-Simons gauge theory of spontaneous vortex phase  

Science Journals Connector (OSTI)

We apply the mutual Chern-Simons effective theory [Kou, Qi, and Weng, Phys. Rev. B 71, 235102 (2005)] of the doped Mott insulator to the study of the so-called spontaneous vortex phase in the low-temperature pseudogap region, which is characterized by strong unconventional superconducting fluctuations. An effective description for the spontaneous vortex phase is derived from the general mutual Chern-Simons Lagrangian, based on which the physical properties including the diamagnetism, spin paramagnetism, magnetoresistance, and the Nernst coefficient, have been quantitatively calculated. The phase boundaries of the spontaneous vortex phase, which sits between the onset temperature Tv and the superconducting transition temperature Tc, are also determined within the same framework. The results are consistent with the experimental measurements of the cuprates.

Xiao-Liang Qi and Zheng-Yu Weng

2007-09-07T23:59:59.000Z

274

Core sizes and dynamical instabilities of giant vortices in dilute Bose-Einstein condensates  

SciTech Connect

Motivated by a recent demonstration of cyclic addition of quantized vorticity into a Bose-Einstein condensate, the vortex pump, we study dynamical instabilities and core sizes of giant vortices. The core size is found to increase roughly as a square-root function of the quantum number of the vortex, whereas the strength of the dynamical instability either saturates to a fairly low value or increases extremely slowly for large quantum numbers. Our studies suggest that giant vortices of very high angular momenta may be achieved by gradually increasing the operation frequency of the vortex pump.

Kuopanportti, Pekko; Lundh, Emil; Huhtamaeki, Jukka A. M.; Pietilae, Ville; Moettoenen, Mikko [Department of Applied Physics/COMP, Aalto University School of Science and Technology, P.O. Box 15100, FI-00076 AALTO (Finland); Department of Physics, Umeaa University, SE-90187 Umeaa (Sweden); Department of Applied Physics/COMP, Aalto University School of Science and Technology, P.O. Box 15100, FI-00076 AALTO, Finland and Department of Physics, Okayama University, Okayama 700-8530 (Japan); Department of Applied Physics/COMP, Aalto University School of Science and Technology, P.O. Box 15100, FI-00076 AALTO, Finland and Australian Research Council Centre of Excellence for Quantum Computer Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney NSW 2052 (Australia); Department of Applied Physics/COMP, Aalto University School of Science and Technology, P.O. Box 15100, FI-00076 AALTO, Finland, Australian Research Council Centre of Excellence for Quantum Computer Technology, School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney NSW 2052 (Australia) and Low Temperature Laboratory, Aalto University School of Science and Technology, P.O. Box 13500, FI-00076 AALTO (Finland)

2010-02-15T23:59:59.000Z

275

Traveling Waves from the Arclength Parameterization: Vortex Sheets with Surface Tension  

E-Print Network (OSTI)

Traveling Waves from the Arclength Parameterization: Vortex Sheets with Surface Tension Benjamin for the vortex sheet with surface tension. We use the angle- arclength description of the interface rather than prove that there exist traveling vortex sheets with surface tension bifurcating from equilibrium. We

Wright, J. Douglas

276

CALTECH ASCI TECHNICAL REPORT 129 On Velocity Structure Functions and the Spherical Vortex Model for  

E-Print Network (OSTI)

the stretched-spiral vortex has been suc- cessfully applied to the calculation of the energy spectrum,6 and some for larger scales is perhaps questionable. Most quantitative vortex-based models have utilized tube and sheetCALTECH ASCI TECHNICAL REPORT 129 On Velocity Structure Functions and the Spherical Vortex Model

Barr, Al

277

Spin dynamics in a spin-correlated radical pair of photosystem I. Pulsed time-resolved EPR at high magnetic field.  

SciTech Connect

Spin-dynamics of the spin-correlated radical pair (SCRP) P{sub 700}{sup +}A{sub 1A}{sup -} in the photosystem I (PSI) reaction center protein have been investigated with high-frequency (HF), time-resolved EPR spectroscopy. The superior spectral resolution of HF EPR enables spin-dynamics for both the donor and acceptor radicals in the pair to be monitored independently. Decay constants of each spin were measured as a function of temperature and compared to data obtained at X-band EPR. Relaxation times, T{sub 1}, and decay rates, k{sub S}, are the same at both X- and D-band magnetic fields. The spin-dynamics within the radical pair were determined from theoretical simulation of experimental time-resolved HF EPR spectra. At low temperatures, T < 60 K, the decay of the SCRP from the singlet state, k{sub S}, is the predominant process, while at high temperatures, T > 130 K, the T{sub 1} relaxation is much faster than k{sub S}. The recombination rate k{sub S} was observed to decrease as the temperature is increased. These EPR spectral results are in agreement with previously reported optical measurements of P{sub 700}{sup +}A{sub 1}{sup -} radical pair recombination.

Poluektov, O. G.; Paschenko, S. V.; Utschig, L. M.; Chemical Sciences and Engineering Division

2009-01-01T23:59:59.000Z

278

Dynamical simulations of magnetically channelled line-driven stellar winds – II. The effects of field-aligned rotation  

Science Journals Connector (OSTI)

......previous magnetohydrodynamics (MHD) simulation study of magnetic...and form the basis for a full MHD description of the rigid body...computed. Figure 4 Schematic diagram illustrating the computation...from the wind. Figure 5 For MHD simulations of the standard model......

Asif Ud-Doula; Stanley P. Owocki; Richard H. D. Townsend

2008-03-21T23:59:59.000Z

279

Vortex Formation in a Plasma Interacting with Neutral Flow  

SciTech Connect

Recently, it has been observed that there exists a class of vortices which rotates in the opposite direction to ExB drift (referred to as anti-ExB vortex). This result suggests that a predominant force other than electric field is acting on ions. It is found that momentum transport and resultant force generation through the interaction between ions and neutral flow play an essential role on anti-ExB vortex formation. The existence of inward neutral flow, which drives the ions in the anti-ExB direction, has been confirmed using a newly-developed high-resolution laser induced fluorescence (LIF) spectroscopy system.

Tanaka, M. Y.; Ogiwara, K.; Etoh, S. [Department of High Energy Engineering Science, Kyushu University, Kasuga-koen 6-1, Kasuga 816-8580 (Japan); Aramaki, M. [Department of Electrical Engineering, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Yoshimura, S. [National Institute for Fusion Science, Oroshi 322-6, Toki 509-5292 (Japan); Varanjes, J. [Center for Plasma Astrophysics, Celestijnenlaan 200 B 3001 Leuven (Belgium)

2008-10-15T23:59:59.000Z

280

Revival of Classical Vortex Generators Now for Transition Delay  

Science Journals Connector (OSTI)

Classical vortex generators, known for their efficiency in delaying or even inhibiting boundary layer separation, are here shown to be coveted devices for transition to turbulence delay. The present devices are miniature with respect to classical vortex generators but are tremendously powerful in modulating the laminar boundary layer in the direction orthogonal to the base flow and parallel to the surface. The modulation generates an additional term in the perturbation energy equation, which counteracts the wall-normal production term and, hence, stabilizes the flow. Our experimental results show that these devices are really effective in delaying transition, but we also reveal their Achilles’ heel.

Shahab Shahinfar; Sohrab S. Sattarzadeh; Jens H. M. Fransson; Alessandro Talamelli

2012-08-16T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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.
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to obtain the most current and comprehensive results.


281

PHYSICAL REVIEW B 85, 134414 (2012) Nonlinear motion of magnetic vortex cores during fast magnetic pulses  

E-Print Network (OSTI)

pulses Keiki Fukumoto* Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198, Japan 351-0198, Japan Toyohiko Kinoshita Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679 Kuniaki Arai Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan

Otani, Yoshichika

282

Field dependence of the vortex structure in d-wave and s-wave superconductors  

Science Journals Connector (OSTI)

We study the vortex structure and its field dependence within the framework of the quasiclassical Eilenberger theory to find the difference between the dx2-y2- and s-wave pairings. We clarify the effect of the dx2-y2-wave nature and the vortex lattice effect on the vortex structure of the pair potential, the internal field and the local density of states. The dx2-y2-wave pairing introduces a fourfold-symmetric structure around each vortex core. With increasing field, their contribution becomes significant to the whole structure of the vortex lattice state, depending on the vortex lattice’s configuration. It is reflected in the form factor of the internal field, which may be detected by small-angle neutron scattering, or the resonance line shape of muon spin resonance and NMR experiments. We also study the induced s- and dxy-wave components around the vortex in dx2-y2-wave superconductors.

Masanori Ichioka; Akiko Hasegawa; Kazushige Machida

1999-04-01T23:59:59.000Z

283

Vortex trimer in three-component Bose-Einstein condensates  

E-Print Network (OSTI)

Vortex trimer is predicted in three-component Bose-Einstein condensates with internal coherent couplings. The molecule is made by three constituent vortices which are bounded by domain walls of the relative phases. We show that the shape and the size of the molecule can be controlled by changing the internal coherent couplings.

Minoru Eto; Muneto Nitta

2012-01-01T23:59:59.000Z

284

High-Resolution Simulations of Parallel BladeVortex Interactions  

E-Print Network (OSTI)

= perturbation pressure coefficient, p ps= 1 2 1U2 1 c = rotor blade chord p = instantaneous airfoil surface­vortex interaction computations Introduction A MAJOR source of rotorcraft noise is generated by the rotor blades on the rotor blades. BVI noise is especially important because it is known to propagate out

Alonso, Juan J.

285

Modified Black Hole with Polar Jet and Vortex  

E-Print Network (OSTI)

There are many models relating an accretion disk of Black Hole to jet outflow. The herein heuristic model describes the continuation of an external accretion disk to an internal accretion disk for less than Black Hole horizon, and subsequent polar jet outflow along polar axis out of polar vortex wherein the event horizon is no longer descriptive.

T. Tmmalm

2001-12-06T23:59:59.000Z

286

Solid State Nuclear Magnetic Resonance Investigation of Polymer Backbone Dynamics in Poly(Ethylene Oxide) Based Lithium and Sodium Polyether-ester-sulfonate Ionomers  

SciTech Connect

Polymer backbone dynamics of single ion conducting poly(ethylene oxide) (PEO)-based ionomer samples with low glass transition temperatures (Tg) have been investigated using solid-state nuclear magnetic resonance (NMR). Experiments detecting 13C with 1H decoupling under magic angle spinning (MAS) conditions identified the different components of the polymer backbone (PEO spacer and isophthalate groups) and their relative mobilities for a suite of lithium- and sodium-containing ionomer samples with varying cation contents. Variable temperature (203-373 K) 1H-13C cross-polarization MAS (CP-MAS) experiments also provided qualitative assessment of the differences in the motions of the polymer backbone components as a function of cation content and identity. Each of the main backbone components exhibit distinct motions, following the trends expected for motional characteristics based on earlier Quasi Elastic Neutron Scattering and 1H spin-lattice relaxation rate measurements. Previous 1H and 7Li spin-lattice relaxation measurements focused on both the polymer backbone and cation motion on the nanosecond timescale. The studies presented here assess the slower timescale motion of the polymer backbone allowing for a more comprehensive understanding of the polymer dynamics. The temperature dependences of 13C linewidths were used to both qualitatively and quantitatively examine the effects of cation content and identity on PEO spacer mobility. Variable contact time 1H-13C CP-MAS experiments were used to further assess the motions of the polymer backbone on the microsecond timescale. The motion of the PEO spacer, reported via the rate of magnetization transfer from 1H to 13C nuclei, becomes similar for T ? 1.1 Tg in all ionic samples, indicating that at similar elevated reduced temperatures the motions of the polymer backbones on the microsecond timescale become insensitive to ion interactions. These results present an improved picture, beyond those of previous findings, for the dependence of backbone dynamics on cation density (and here, cation identity as well) in these amorphous PEO-based ionomer systems.

Roach, David J. [Penn State Univ., State College, PA (United States). Dept. of Chemistry; Dou, Shichen [Penn State Univ., State College, PA (United States). Dept. of Materials Science and Engineering; Colby, Ralph H. [Penn State Univ., State College, PA (United States). Dept. of Materials Science and Engineering; Mueller, Karl T. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Penn State Univ., State College, PA (United States). Dept. of Chemistry

2013-05-21T23:59:59.000Z

287

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

288

Higher Derivative Corrections to Non-Abelian Vortex Effective Theory  

E-Print Network (OSTI)

We give a systematic method to calculate higher derivative corrections to low-energy effective theories of solitons, which are in general non-linear sigma models on the moduli spaces of the solitons. By applying it to the effective theory of a single BPS non-Abelian vortex in U(N) gauge theory with N fundamental Higgs fields, we obtain four derivative corrections to the effective sigma model on the moduli space C \\times CP^{N-1}. We compare them with the Nambu-Goto action and the Faddeev-Skyrme model. We also show that Yang-Mills instantons/monopoles trapped inside a non-Abelian vortex membrane/string are not modified in the presence of higher derivative terms.

Minoru Eto; Toshiaki Fujimori; Muneto Nitta; Keisuke Ohashi; Norisuke Sakai

2012-04-03T23:59:59.000Z

289

Precession of a single vortex line in superfluid B3  

Science Journals Connector (OSTI)

This paper reports the discovery of a new vortex phenomenon in superfluid B3. A single filament of quantized vortex line precesses as a solid body around a wire extending along the axis of a cylinder. The precession frequency equals the angular velocity of the apparatus at which the presence of a single quantum of circulation minimizes the system’s free energy. The period of precession is related to the circulation quantum and the dimensions of the apparatus. Thus a measurement of the precession period is an accurate determination of the quantum unit. We find ?=(1.020±0.03)h/2m3, where m3 is the mass of the He3 atom.

R. J. Zieve; Yu. Mukharsky; J. D. Close; J. C. Davis; R. E. Packard

1992-03-02T23:59:59.000Z

290

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

291

Vortex energy and 360 Neel walls in thinfilm  

E-Print Network (OSTI)

.Ignat@math.u-psud.fr) Courant Institute, New York University, New York, NY 10012, USA (e-mail: knuepfer@cims.nyu.edu) 1 #12Vortex energy and 360 ­N´eel walls in thin­film micromagnetics Radu Ignat , Hans Kn¨upfer October-section. The model is based on the following energy functional: E2d (m) = Z B2 |m|2 dx + | ln | 2 Z R2 ||-1

292

Coherence Current, Coherence Vortex, and the Conservation Law of Coherence  

Science Journals Connector (OSTI)

Introducing scalar and vector densities for a mutual coherence function, we present a new conservation law for optical coherence of scalar wave fields in the form of a continuity equation. This coherence conservation law provides new insights into topological phenomena for the complex coherence function. Some properties related to the newly introduced coherence vector density, such as a circulating coherence current associated with a coherence vortex, are investigated both theoretically and experimentally for the first time.

Wei Wang and Mitsuo Takeda

2006-06-08T23:59:59.000Z

293

Transient vortex events in the initial value problem for turbulence  

E-Print Network (OSTI)

A vorticity surge event that could be a paradigm for a wide class of bursting events in turbulence is studied to examine how the energy cascade is established and how this event could serve as a new test of LES turbulence models. This vorticity surge event is tied to the formation of the energy cascade in a direct numerical simulation by the traditional signatures of a turbulent energy cascade such as spectra approaching -5/3 and strongly Beltramized vortex tubes. A coherent mechanism is suggested by the nearly simultaneous development of a maximum of the peak vorticity $\\|\\omega\\|_\\infty$, growth of the dissipation, the appearance of a helically aligned local vortex configuration and strong, transient oscillations in the helicity wavenumber spectrum. This coherence is also examined for two LES models, a traditional purely dissipative eddy viscosity model and a modern method (LANS$-\\alpha$) that respects the nonlinear transport properties of fluids. Both LES models properly represent the spectral energy and energy dissipation associated with this vorticity surge event. However, only the model that preserves nonlinear fluid transport properties reproduces the helical properties, including Beltrami-like vortex tubes.

Darryl D. Holm; Robert M. Kerr

2001-10-19T23:59:59.000Z

294

Coherence Holography and Spatial Frequency Comb for 3-D Coherence Imaging and Coherence Vortex Generation  

Science Journals Connector (OSTI)

The principle and the applications of a recently proposed unconventional holography technique, coherence holography, applied for coherence vortex generation, and a related technique...

Takeda, Mitsuo; Wang, Wei; Duan, Zhihui; Miyamoto, Yoko; Rosen, Joseph

295

Vortex shedding from square plates near a ground plane: an experimental study.  

E-Print Network (OSTI)

??Vortex shedding frequencies were obtained experimentally for square plates near a ground plane in the Texas Tech wind tunnel. These frequencies, in the form of… (more)

Matty, Rosemary Ricohermoso

1979-01-01T23:59:59.000Z

296

Rotational Doppler-effect due to selective excitation of vector-vortex field in optical fiber  

Science Journals Connector (OSTI)

Experimental demonstration of rotational Doppler-effect due to direct and simultaneous excitation of orthogonal elliptically-polarized fundamental and vortex modes in a two-mode...

Inavalli, V V G Krishna; Viswanathan, Nirmal K

2011-01-01T23:59:59.000Z

297

residual magnetism  

Science Journals Connector (OSTI)

The magnetization, i.e., the magnetic polarization, that remains in a magnetized material after all attempts to remove the magnetization have been made. Note: An example of residual magnetization is the magnetiza...

2001-01-01T23:59:59.000Z

298

NUMERICAL EXPERIMENTS ON THE TWO-STEP EMERGENCE OF TWISTED MAGNETIC FLUX TUBES IN THE SUN  

SciTech Connect

We present the new results of the two-dimensional numerical experiments on the cross-sectional evolution of a twisted magnetic flux tube rising from the deeper solar convection zone (-20,000 km) to the corona through the surface. The initial depth is 10 times deeper than most of the previous calculations focusing on the flux emergence from the uppermost convection zone. We find that the evolution is illustrated by the following two-step process. The initial tube rises due to its buoyancy, subject to aerodynamic drag due to the external flow. Because of the azimuthal component of the magnetic field, the tube maintains its coherency and does not deform to become a vortex roll pair. When the flux tube approaches the photosphere and expands sufficiently, the plasma on the rising tube accumulates to suppress the tube's emergence. Therefore, the flux decelerates and extends horizontally beneath the surface. This new finding owes to our large-scale simulation, which simultaneously calculates the dynamics within the interior as well as above the surface. As the magnetic pressure gradient increases around the surface, magnetic buoyancy instability is triggered locally and, as a result, the flux rises further into the solar corona. We also find that the deceleration occurs at a higher altitude than assumed in our previous experiment using magnetic flux sheets. By conducting parametric studies, we investigate the conditions for the two-step emergence of the rising flux tube: field strength {approx}> 1.5 x 10{sup 4} G and the twist {approx}> 5.0 x 10{sup -4} km{sup -1} at -20,000 km depth.

Toriumi, S.; Yokoyama, T., E-mail: toriumi@eps.s.u-tokyo.ac.jp [Department of Earth and Planetary Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2011-07-10T23:59:59.000Z

299

Evolution of small-scale magnetic elements in the vicinity of granular-size swirl convective motions  

E-Print Network (OSTI)

Advances in solar instrumentation have led to a widespread usage of time series to study the dynamics of solar features, specially at small spatial scales and at very fast cadences. Physical processes at such scales are determinant as building blocks for many others occurring from the lower to the upper layers of the solar atmosphere and beyond, ultimately for understanding the bigger picture of solar activity. Ground-based (SST) and space-borne (Hinode) high-resolution solar data are analyzed in a quiet Sun region displaying negative polarity small-scale magnetic concentrations and a cluster of bright points observed in G-band and Ca II H images. The studied region is characterized by the presence of two small-scale convective vortex-type plasma motions, one of which appears to be affecting the dynamics of both, magnetic features and bright points in its vicinity and therefore the main target of our investigations. We followed the evolution of bright points, intensity variations at different atmospheric heig...

Dominguez, S Vargas; Balmaceda, L; Cabello, I; Domingo, V

2014-01-01T23:59:59.000Z

300

VOLUME 84, NUMBER 2 P H Y S I C A L R E V I E W L E T T E R S 10 JANUARY 2000 Collapse Dynamics of Liquid Bridges Investigated by Time-Varying Magnetic Levitation  

E-Print Network (OSTI)

VOLUME 84, NUMBER 2 P H Y S I C A L R E V I E W L E T T E R S 10 JANUARY 2000 Collapse Dynamics of Liquid Bridges Investigated by Time-Varying Magnetic Levitation Milind P. Mahajan,1 Mesfin Tsige,1 was discovered for the collapse time of a liquid bridge. A paramagnetic liquid was suspended between the tips

Taylor, Philip L.

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

Manifestations of magnetic vortices in equation of state of Yang-Mills plasma  

E-Print Network (OSTI)

The vacuum of Yang-Mills theory contains singular stringlike objects identified with center (magnetic) vortices. Percolation of magnetic vortices is known to be responsible for the color confinement in the low-temperature phase of the theory. In our work we study properties of the vortices at finite temperature using lattice simulations of SU(2) gauge theory. We show that magnetic vortices provide a numerically large contribution to thermodynamic quantities of the gluon plasma in Yang-Mills theory. In particular, we observe that in the deconfinement phase at temperatures T_c energy-momentum tensor. In the confinement phase the vortex contribution is positive. The thermodynamical significance of the magnetic objects allows us to suggest that the quark-gluon plasma may contain a developed network of magnetic flux tubes. The existence of the vortex network may lead to observable effects in the quark-gluon plasma because the chromomagnetic field of the vortices should scatter and drag quarks.

M. N. Chernodub; Atsushi Nakamura; V. I. Zakharov

2008-07-31T23:59:59.000Z

302

Manifestations of magnetic vortices in equation of state of Yang-Mills plasma  

E-Print Network (OSTI)

The vacuum of Yang-Mills theory contains singular stringlike objects identified with center (magnetic) vortices. The percolation of the magnetic vortices is known to be responsible for the color confinement in the low-temperature phase of the theory. In our work we study properties of the vortices at finite temperature using lattice simulations of SU(2) gauge theory. We show that magnetic vortices provide numerically large contribution to thermodynamic quantities of gluon plasma in Yang-Mills theory. In particular, we observe that in the deconfinement phase at temperatures Tc energy-momentum tensor. In the confinement phase the vortex contribution is positive. The thermodynamical significance of the magnetic objects allows us to suggest that the quark gluon plasma may contain a developed network of the magnetic flux tubes. The existence of the vortex network may lead to observable eff...

Chernodub, M N; Zakharov, V I

2008-01-01T23:59:59.000Z

303

IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 16, NO. 3, MAY/JUNE 2010 691 Dynamics of Magnetic Nanoparticle-Based Contrast  

E-Print Network (OSTI)

of Magnetic Nanoparticle-Based Contrast Agents in Tissues Tracked Using Magnetomotive Optical Coherence assessment of magnetic nanoparticles in tissues. In this study, we demonstrate the use of MM-OCT for quantitative measurement of magnetic iron oxide nanoparticle transport and concentration in ex vivo muscle

Boppart, Stephen

304

Vortex-induced vibration of a circular cylinder with combined in-line and cross-flow motion  

E-Print Network (OSTI)

Deep water, string-like, marine risers subject to strong ocean currents, suffer from vortex-induced vibrations (VIV), where vortex shedding interacts with the structural properties of the riser, resulting in large amplitude ...

Dahl, Jason (Jason Michael)

2008-01-01T23:59:59.000Z

305

Probing the anisotropic vortex lattice in the Fe-based superconductor KFe2As2 using small angle neutron scattering  

SciTech Connect

Using small angle neutron scattering, the anisotropy of the magnetic vortex lattice (VL), in the heavily hole-doped pnictide superconductor, KFe2As2, was studied. Well-ordered VL scattering patterns were measured with elds applied in directions between B k c and the basal plane, rotating either towards [100] or [110]. Slightly distorted hexagonal patterns were observed when B k c. However, the scattering pattern distorted strongly as the eld was rotated away from the c- axis. At low eld, the arrangement of vortices is strongly aected by the anisotropy of penetration depth in the plane perpendicular to the eld. By tting the distortion with the anisotropic London model, we obtained an estimate of 3:4 for the anisotropy factor, , between the in-plane and c-axis penetration depths at the lowest temperature studied. The results further reveal VL phase transitions as a function of eld direction. We discuss these transitions using the "Hairy Ball" theorem.

Debeer-Schmitt, Lisa M [ORNL] [ORNL; Dewhurst, Charles [Institut Laue-Langevin (ILL)] [Institut Laue-Langevin (ILL); Kikuchi, Hiroko [Ochanomizu University, Japan] [Ochanomizu University, Japan; Cameron, Alistair [University of Birmingham, The, Birmingham, United Kingdom] [University of Birmingham, The, Birmingham, United Kingdom; Heslop, Richard [University of Birmingham, The, Birmingham, United Kingdom] [University of Birmingham, The, Birmingham, United Kingdom; Forgan, E. M. [University of Birmingham, The, Birmingham, United Kingdom] [University of Birmingham, The, Birmingham, United Kingdom; Bowell, Charlotte [University of Cambridge] [University of Cambridge; White, Jonathon [Laboratory for Neutron Scattering ETHZ & PSI] [Laboratory for Neutron Scattering ETHZ & PSI; Gavilano, Jorge [ETH Zurich, Switzerland] [ETH Zurich, Switzerland

2013-01-01T23:59:59.000Z

306

van Hove singularities and vortex motion in superconductors B. I. Ivlev,1,2  

E-Print Network (OSTI)

´ 78000, Mexico Received 16 February 2001; published 18 June 2001 When vortices move in a type by an electric current, any peculiarity of the vortex radiation friction due to emission of acoustic waves vortices. When a vortex moves under the action of a transport electric current, an electric field

Kunchur, Milind N.

307

Modeling bubble-vortex interactions Modeling and simulation of multiple bubble entrainment and interactions with two  

E-Print Network (OSTI)

Modeling bubble-vortex interactions Modeling and simulation of multiple bubble entrainment, OR 97331. (Dated: 5 November 2010) 1 #12;Modeling bubble-vortex interactions Simulations of bubble direct numerical simulation whereas motion of subgrid bubbles is modeled using Lagrangian track- ing

Apte, Sourabh V.

308

Generation and Propagation of InertiaGravity Waves from Vortex Dipoles and Jets SHUGUANG WANG*  

E-Print Network (OSTI)

Generation and Propagation of Inertia­Gravity Waves from Vortex Dipoles and Jets SHUGUANG WANG) ABSTRACT This study investigates gravity wave generation and propagation from jets within idealized vortex, geostrophic adjust- ment, and spontaneous generation (Fritts and Alexander 2003, and references therein

309

Dynamics of strings between walls  

SciTech Connect

Configurations of vortex-strings stretched between or ending on domain walls were previously found to be 1/4 BPS states. Among zero modes of string positions, the center of mass of strings in each region between two adjacent domain walls is shown to be non-normalizable whereas the rests are normalizable. We study dynamics of vortex-strings stretched between separated domain walls by using two methods, the moduli space (geodesic) approximation of full 1/4 BPS states and the charged particle approximation for string endpoints in the wall effective action. In the first method we obtain the effective Lagrangian explicitly and find the 90 degree scattering for head-on collision. In the second method the domain wall effective action is assumed to be U(1){sup N} gauge theory, and we find a good agreement between two methods for well separated strings. This talk is based on the work [1].

Eto, Minoru [INFN, Sezione di Pisa, Largo Pontecorvo, 3, Ed. C, 56127 Pisa (Italy); Fujimori, Toshiaki; Nagashima, Takayuki [Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551 (Japan); Nitta, Muneto [Department of Physics, Keio University, Hiyoshi, Yokohama, Kanagawa 223-8521 (Japan); Ohashi, Keisuke [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, CB3 0WA (United Kingdom); Sakai, Norisuke [Department of Mathematics, Tokyo Woman's Christian University, Tokyo 167-8585 (Japan)

2008-11-23T23:59:59.000Z

310

Stripe Domains and First-Order Phase Transition in the Vortex Matter of Anisotropic High-Temperature Superconductors  

E-Print Network (OSTI)

Stripe Domains and First-Order Phase Transition in the Vortex Matter of Anisotropic High-Temperature temperature superconductor and reveal a sharp transition in the state of this phase resulting in regular that can subsequently melt at high temperatures to a vortex liquid, a pinned vortex glassy state that can

Alexei, Koshelev

311

Effect of time-dependent piston velocity program on vortex ring formation in a piston/cylinder arrangement  

E-Print Network (OSTI)

Effect of time-dependent piston velocity program on vortex ring formation in a piston An analytical model describing laminar vortex ring formation in a nozzle flow generator piston/ cylinder.1063/1.2188918 I. INTRODUCTION Vortex rings are usually generated in the laboratory by the motion of a piston

Dabiri, John O.

312

arXiv:1206.2498v2[cond-mat.other]19Nov2012 Quantum vortex reconnections  

E-Print Network (OSTI)

, and parts of the initial vortical tubes can be left behind as vortex threads, which then undergo successivearXiv:1206.2498v2[cond-mat.other]19Nov2012 Quantum vortex reconnections S. Zuccher,1 M. Caliari,1 A with time before and after the vor- tex reconnection. We also compute vortex reconnections using the Biot

Caliari, Marco

313

The role of boundary conditions in a simple model of incipient vortex breakdown F. Gallaire and J.-M. Chomaz  

E-Print Network (OSTI)

. In the labora- tory, it is preferentially studied in vortex tubes, where it is seen in many cases to give riseThe role of boundary conditions in a simple model of incipient vortex breakdown F. Gallaire and J of a hairpin vortex in a shear-thinning fluid governed by a power-law model Phys. Fluids 25, 101703 (2013); 10

Boyer, Edmond

314

Collective Effects in Vortex Movements in Complex Plasmas  

Science Journals Connector (OSTI)

We study the onset and characteristics of vortices in complex (dusty) plasmas using two-dimensional simulations in a setup modeled after the PK-3 Plus laboratory. A small number of microparticles initially self-arranges in a monolayer around the void. As additional particles are introduced, an extended system of vortices develops due to a nonzero curl of the plasma forces. We demonstrate a shear-thinning effect in the vortices. Velocity structure functions and the energy and enstrophy spectra show that vortex flow turbulence is present that is in essence of the “classical” Kolmogorov type.

Mierk Schwabe, Sergey Zhdanov, Christoph Räth, David B. Graves, Hubertus M. Thomas, and Gregor E. Morfill

2014-03-19T23:59:59.000Z

315

Noninvasive Monitoring of Microvascular Changes With Partial Irradiation Using Dynamic Contrast-Enhanced and Blood Oxygen Level-Dependent Magnetic Resonance Imaging  

SciTech Connect

Purpose: The microvasculature of a tumor plays an important role in its response to radiation therapy. Dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) and blood oxygen level-dependent (BOLD) MRI are both sensitive to vascular characteristics. The present study proposed a partial irradiation approach to a xenograft tumor to investigate the intratumoral response to radiation therapy using DCE and BOLD MRI. Methods and Materials: TRAMP-C1 tumors were grown in C57BL/6J mice. Partial irradiation was performed on the distal half of the tumor with a single dose of 15 Gy. DCE MRI was performed to derive the endothelium transfer constant, K{sup trans}, using pharmacokinetic analysis. BOLD MRI was performed using quantitative R2* measurements with carbogen breathing. The histology of the tumor was analyzed using hematoxylin and eosin staining and CD31 staining to detect endothelial cells. The differences between the irradiated and nonirradiated regions of the tumor were assessed using K{sup trans} values, ?R2* values in response to carbogen and microvascular density (MVD) measurements. Results: A significantly increased K{sup trans} and reduced BOLD response to carbogen were found in the irradiated region of the tumor compared with the nonirradiated region (P<.05). Histologic analysis showed a significant aggregation of giant cells and a reduced MVD in the irradiated region of the tumor. The radiation-induced difference in the BOLD response was associated with differences in MVD and K{sup trans}. Conclusions: We demonstrated that DCE MRI and carbogen-challenge BOLD MRI can detect differential responses within a tumor that may potentially serve as noninvasive imaging biomarkers to detect microvascular changes in response to radiation therapy.

Lin, Yu-Chun [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China) [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Department of Electrical Engineering, Chang Gung University, Linkou, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Wang, Jiun-Jie [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China) [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Hong, Ji-Hong [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China) [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Lin, Yi-Ping [Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China)] [Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Lee, Chung-Chi [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China) [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Wai, Yau-Yau; Ng, Shu-Hang; Wu, Yi-Ming [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China) [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Wang, Chun-Chieh, E-mail: jjwang@adm.cgmh.org.tw [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China) [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China)

2013-04-01T23:59:59.000Z

316

Noninvasive Assessment of Tumor Microenvironment Using Dynamic Contrast-Enhanced Magnetic Resonance Imaging and {sup 18}F-Fluoromisonidazole Positron Emission Tomography Imaging in Neck Nodal Metastases  

SciTech Connect

Purpose: To assess noninvasively the tumor microenvironment of neck nodal metastases in patients with head-and-neck cancer by investigating the relationship between tumor perfusion measured using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and hypoxia measured by {sup 18}F-fluoromisonidazole ({sup 18}F-FMISO) positron emission tomography (PET). Methods and Materials: Thirteen newly diagnosed head-and-neck cancer patients with metastatic neck nodes underwent DCE-MRI and {sup 18}F-FMISO PET imaging before chemotherapy and radiotherapy. The matched regions of interests from both modalities were analyzed. To examine the correlations between DCE-MRI parameters and standard uptake value (SUV) measurements from {sup 18}F-FMISO PET, the nonparametric Spearman correlation coefficient was calculated. Furthermore, DCE-MRI parameters were compared between nodes with {sup 18}F-FMISO uptake and nodes with no {sup 18}F-FMISO uptake using Mann-Whitney U tests. Results: For the 13 patients, a total of 18 nodes were analyzed. The nodal size strongly correlated with the {sup 18}F-FMISO SUV ({rho} = 0.74, p < 0.001). There was a strong negative correlation between the median k{sub ep} (redistribution rate constant) value ({rho} = -0.58, p = 0.042) and the {sup 18}F-FMISO SUV. Hypoxic nodes (moderate to severe {sup 18}F-FMISO uptake) had significantly lower median K{sup trans} (volume transfer constant) (p = 0.049) and median k{sub ep} (p = 0.027) values than did nonhypoxic nodes (no {sup 18}F-FMISO uptake). Conclusion: This initial evaluation of the preliminary results support the hypothesis that in metastatic neck lymph nodes, hypoxic nodes are poorly perfused (i.e., have significantly lower K{sup trans} and k{sub ep} values) compared with nonhypoxic nodes.

Jansen, Jacobus [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Schoeder, Heiko [Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Lee, Nancy Y. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Wang Ya [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States)

2010-08-01T23:59:59.000Z

317

Interaction of Josephson Junction and Distant Vortex in Narrow Thin-Film Superconducting Strips  

SciTech Connect

The phase difference between the banks of an edge-type planar Josephson junction crossing the narrow thin-film strip depends on wether or not vortices are present in the junction banks. For a vortex close to the junction this effect has been seen by Golod, Rydh, and Krasnov [Phys. Rev. Lett. 104, 227003 (2010)], who showed that the vortex may turn the junction into ? type. It is shown here that even if the vortex is far away from the junction, it still changes the 0 junction to a ? junction when situated close to the strip edges. Within the approximation used, the effect is independent of the vortex-junction separation, a manifestation of the topology of the vortex phase which extends to macroscopic distances of superconducting coherence.

Kogan, V. G. [Ames Laboratory; Mints, R. G. [Tel Aviv University

2014-01-31T23:59:59.000Z

318

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

319

Static solitons of the sine-Gordon equation and equilibrium vortex structure in Josephson junctions  

SciTech Connect

The problem of vortex structure in a single Josephson junction in an external magnetic field, in the absence of transport currents, is reconsidered from a new mathematical point of view. In particular, we derive a complete set of exact analytical solutions representing all the stationary points (minima and saddle-points) of the relevant Gibbs free-energy functional. The type of these solutions is determined by explicit evaluation of the second variation of the Gibbs free-energy functional. The stable (physical) solutions minimizing the Gibbs free-energy functional form an infinite set and are labeled by a topological number N{sub v}=0,1,2,... . Mathematically, they can be interpreted as nontrivial 'vacuum' (N{sub v}=0) and static topological solitons (N{sub v}=1,2,...) of the sine-Gordon equation for the phase difference in a finite spatial interval: solutions of this kind were not considered in previous literature. Physically, they represent the Meissner state (N{sub v}=0) and Josephson vortices (N{sub v}=1,2,...). Major properties of the new physical solutions are thoroughly discussed. An exact, closed-form analytical expression for the Gibbs free energy is derived and analyzed numerically. Unstable (saddle-point) solutions are also classified and discussed.

Kuplevakhsky, S. V.; Glukhov, A. M. [B. I. Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, 47 Lenin Avenue, 61103 Kharkov (Ukraine)

2006-01-01T23:59:59.000Z

320

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.

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

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.

322

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.

323

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.

324

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.

325

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.

326

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.

327

Development of a free vortex wake method code for offshore floating wind turbines  

Science Journals Connector (OSTI)

Offshore floating wind turbines (OFWTs) present unique aerodynamic analysis challenges. Motion–derived velocity perturbations in the wake necessitate higher–fidelity aerodynamic analysis methods than the ubiquitous momentum balance techniques currently in use. A more physically–sound approach is to model the wake generated by a wind turbine rotor as a freely convecting lattice, using the resultant inflow to estimate rotor loads, as it done with a free vortex wake method (FVM). The FVM code Wake Induced Dynamics Simulator (WInDS) was developed at the University of Massachusetts at Amherst to predict the aerodynamic loading and wake evolution of an OFWT to a higher degree of accuracy than is possible via momentum balance methods. A series of validation cases were conducted to provide some basis for applying \\{WInDS\\} to floating wind turbine cases, for which no aerodynamic experimental data is currently available. The results from these tests show that \\{WInDS\\} is able to accurately predict the aerodynamically–derived loads and wake structures generated by various fixed and rotary–wing cases, and may therefore be applied to more complex cases, like OFWTs, with a degree of confidence.

T. Sebastian; M.A. Lackner

2012-01-01T23:59:59.000Z

328

866 IEEE TRANSACTIONS ON MAGNETICS, VOL. 44, NO. 6, JUNE 2008 Dynamical Models for Eddy Current in Ferromagnetic Cores Introduced in  

E-Print Network (OSTI)

is composed of a magnet, a mas- sive circuit, a mobile vane linked to a spring, and a coil. Fig. 1 shows a current appears in the coil, the force created by the spring becomes inferior to the one created by the magnet and the coil; thus, the relay trips. A. Modeling of the Device Thanks to 3-D nonlinear FE model

Boyer, Edmond

329

Random center vortex lines in continuous 3D space-time  

E-Print Network (OSTI)

We present a model of center vortices, represented by closed random lines in continuous 2+1- dimensional space- time. These random lines are modeled as being piece-wise linear and an ensemble is generated by Monte Carlo methods. The physical space in which the vortex lines are defined is a cuboid with periodic boundary conditions. Besides moving, growing and shrinking of the vortex configuration, also reconnections are allowed. Our ensemble therefore contains not a fixed, but a variable number of closed vortex lines. This is expected to be important for realizing the deconfining phase transition. Using the model, we study both vortex percolation and the potential V (R) between quark and anti-quark as a function of distance R at different vortex densities, vortex segment lengths, reconnection conditions and at different temperatures. We have found three deconfinement phase transitions, as a function of density, as a function of vortex segment length, and as a function of temperature. The model reproduces the qualitative features of confinement physics seen in SU(2) Yang-Mills theory.

Roman Höllwieser; Derar Altarawneh; Michael Engelhardt

2014-11-26T23:59:59.000Z

330

Nano-crystallization and magnetic mechanisms of Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} amorphous alloy by ab initio molecular dynamics simulation  

SciTech Connect

Iron-based amorphous and nano-crystalline alloys have attracted a growing interest due to their potential in the application of magnetic coil production. However, fundamental understanding of the nano-crystallization mechanisms and magnetic features in the amorphous structure are still lack of knowledge. In the present work, we performed ab initio molecular dynamics simulation to clarify the ionic and electronic structure in atomic scale, and to derive the origin of the good magnetic property of Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} amorphous alloy. The simulation gave a direct evidence of the Cu-P bonding preference in the amorphous alloy, which may promote nucleation in nano-crystallization process. On the other hand, the electron transfer and the band/orbital features in the amorphous alloy suggests that alloying elements with large electronegativity and the potential to expand Fe disordered matrix are preferred for enhancing the magnetization.

Wang, Yaocen; Takeuchi, Akira; Makino, Akihiro [Institute for Material Research, Tohoku University, Sendai 980-8577 (Japan); Liang, Yunye [New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579 (Japan); Kawazoe, Yoshiyuki [New Industry Creation Hatchery Center, Tohoku University, Sendai 980-8579 (Japan); Kutateladze Institute of Thermophysics, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk (Russian Federation)

2014-05-07T23:59:59.000Z

331

ASSESSMENT OF WAKE VORTEX SEPARATION DISTANCES USING THE WAVIR TOOLSET  

E-Print Network (OSTI)

) and Failure Modes and Effects Analysis (FMEA), are not easily applied due the dynamic stochastic nature

332

Experimental optimization of a free vortex propeller runner for micro hydro application  

SciTech Connect

The turbine technology for low head application in the micro hydro range has been vastly neglected despite niche available in scattered regions of valley flows as well as in wastewater canals and other energy recovery schemes, where the available head does not exceed 2 meters. The goal of this study is to develop hydraulically optimized propeller turbines for the micro hydro range with a particular focus on ease of manufacture. This paper presents a wide range of geometrical optimization steps carried out on a propeller runner, whose blades have been designed using the free vortex theory, and operating with a gross head from 1.5 to 2 m and discharge of approximately 75 l/s. It further illustrates 3 stages of geometrical modifications carried out on the runner with an objective of optimizing the runner performance. These modifications comprised of changes to the tip angles (both at the runner inlet and exit) as well as the hub angles (at the runner inlet) of the runner blades. The paper also presents an interesting theoretical methodology to analyze the effects of each optimization stage. This method looks at the relative changes to shaft power and discharge at constant head and speed and gives wonderful insight as to how the internal parameters like Euler shaft work and runner hydraulic losses are behaving with respect to each optimization stage. It was found that the performance of the runner was very sensitive to changes to exit tip angle. At two levels of modification, the discharge increased in the range of 15-30%, while shaft power increased in the range of 12-45%, thus influencing the efficiency characteristics. The results of the runner inlet tip modification were very interesting in that a very significant rise of turbine efficiency was recorded from 55% to 74% at the best efficiency point, which was caused by a reduced discharge consumption as well as a higher power generation. It was also found that the optimization study on a propeller runner has reasonably validated the estimates of the free vortex theory despite small deviations. The final runner configuration demonstrated a maximum efficiency of 74% ({+-}1.8%), which is very encouraging from the perspectives of micro hydro application. The paper concludes with recommendations of a series of optimization steps to increase the efficiency of the runner. It also recommends the attempt of Computational Fluid Dynamics both as a validation and optimization tool for future research on propeller runners. (author)

Singh, Punit; Nestmann, Franz [Institute for Water and River Basin Management (IWG), University of Karlsruhe, Kaiser Str. 12, D 76128 Karlsruhe (Germany)

2009-09-15T23:59:59.000Z

333

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

334

Magnetic Spinner  

Science Journals Connector (OSTI)

A science toy sometimes called the “magnetic spinner” is an interesting class demonstration to illustrate the principles of magnetic levitation. It can also be used to demonstrate Faraday's law and a horizontally suspended physical pendulum. The levitated part contains two circular magnets encased in a plastic housing. Each magnet stays above two triangular magnets fixed to the base. The magnetic repulsive force experienced by the circular magnets is independent of their orientation; therefore the holder of these magnets can be rotated without affecting its stability. The holder with the circular magnets can be oscillated up and down as a horizontally suspended physical pendulum.

P. J. Ouseph

2006-01-01T23:59:59.000Z

335

Magnetism Digest  

Science Journals Connector (OSTI)

... and Institute of Electrical and Electronic Engineers, on the occasion of their annual conferences on magnetism and magnetic materials in the United States, have sponsored the production of a Magnetic ... references, drawn from a large number of sources, to work in the field of magnetism and magnetic materials published in the preceding year. They therefore provide a very convenient ...

J. H. PHILLIPS

1966-06-25T23:59:59.000Z

336

Observation of Dirac Monopoles in a Synthetic Magnetic Field  

E-Print Network (OSTI)

Magnetic monopoles --- particles that behave as isolated north or south magnetic poles --- have been the subject of speculation since the first detailed observations of magnetism several hundred years ago. Numerous theoretical investigations and hitherto unsuccessful experimental searches have followed Dirac's 1931 development of a theory of monopoles consistent with both quantum mechanics and the gauge invariance of the electromagnetic field. The existence of even a single Dirac magnetic monopole would have far-reaching physical consequences, most famously explaining the quantization of electric charge. Although analogues of magnetic monopoles have been found in exotic spin-ices and other systems, there has been no direct experimental observation of Dirac monopoles within a medium described by a quantum field, such as superfluid helium-3. Here we demonstrate the controlled creation of Dirac monopoles in the synthetic magnetic field produced by a spinor Bose-Einstein condensate. Monopoles are identified, in both experiments and matching numerical simulations, at the termini of vortex lines within the condensate. By directly imaging such a vortex line, the presence of a monopole may be discerned from the experimental data alone. These real-space images provide conclusive and long-awaited experimental evidence of the existence of Dirac monopoles. Our result provides an unprecedented opportunity to observe and manipulate these quantum-mechanical entities in a controlled environment.

M. W. Ray; E. Ruokokoski; S. Kandel; M. Möttönen; D. S. Hall

2014-08-13T23:59:59.000Z

337

CFD Numerical Simulation of Vortex-Induced Vibration of a Stay Cable under a Wind Profile  

Science Journals Connector (OSTI)

VIV (Vortex-induced vibration) of a stay cable subjected to a wind profile is numerically simulated through combining CFD ... numerical model. Under a profile of mean wind speed, unsteady aerodynamic lift coeffic...

Wenli Chen; Hui Li

2009-01-01T23:59:59.000Z

338

Optimal Excitation of Asymmetric Perturbations on an Axisymmetric Barotropic Vortex: A linear Singular Value Analysis  

Science Journals Connector (OSTI)

Singular vectors on a barotropic circular vortex consisting of three regions of piecewise-constant vorticity are investigated under the L2-norm to reveal the shape and growth rate of possible perturbations that may contribute to the formation of ...

Toshihisa Itano

339

E-Print Network 3.0 - axially-symmetric cyclonic vortex Sample...  

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

> >> 1 1 APRIL 2002 1213W A N G 2002 American Meteorological Society Summary: and wind fields of the vortex Rossby waves are quasi-balanced, with confluent cyclonic (divergent... ,...

340

Ultraviolet vortex generation using periodically bonded ?-BaB2O4 device  

Science Journals Connector (OSTI)

This paper describes the first demonstration of ultraviolet (266nm) vortex generation using the combination of a frequency-doubled nanosecond green laser, a spiral phase plate, and a...

Sasaki, Yuta; Koyama, Mio; Miyamoto, Katsuhiko; Ariga, Yoshimi; Onda, Tomomi; Shoji, Ichiro; Omatsu, Takashige

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

Vortex-Induced Vibration of a slender horizontal cylinder in currents and waves  

E-Print Network (OSTI)

Vortex-Induced Vibration (VIV) is a concern when dealing with slender, flexible structural members of deepwater platforms. While much is known about the characteristics of VIV in uniform and sheared current flows, very little is known about...

Chitwood, James Scott

2012-06-07T23:59:59.000Z

342

Application of fiber Bragg grating based strain sensor in pipeline vortex-induced vibration measurement  

Science Journals Connector (OSTI)

The vortex-induced vibrations (VIV) is an important topic of ... of different methods have been applied to the measurement of VIV, especially for the elongated, ... in stainless steel tubes were applied to the measurement

Liang Ren; ZiGuang Jia; Michael Siu Chun Ho…

2014-09-01T23:59:59.000Z

343

The Roles of Vortex Rossby Waves in Hurricane Secondary Eyewall Formation  

Science Journals Connector (OSTI)

A high-resolution, full-physics model initiated with an idealized tropical cyclone–like vortex is used to simulate and investigate the secondary eyewall formation. The beta skirt axisymmetrization (BSA) hypothesis previously proposed is examined ...

Xin Qiu; Zhe-Min Tan; Qingnong Xiao

2010-06-01T23:59:59.000Z

344

Vortex life cycles in two-and three-layer quasi-geostrophic models  

E-Print Network (OSTI)

Coherent vortices and their properties were studied in two- and three-layer quasi-geostrophic beta-plane turbulence. Much research has discussed vortex characteristics in a number of applications, but no significant study of vortices in turbulent...

Fox, Amanda Katherine

2012-06-07T23:59:59.000Z

345

Vortex Induced Vibrations of cylinders : experiments in reducing drag force and amplitude of motion  

E-Print Network (OSTI)

Reducing the deleterious effect of Vortex Induced Vibrations (VIV) in marine risers is an important task for ocean engineers; and many competing factors exist in the design of VIV suppression devices. This thesis explores ...

Farrell, David Emmanuel

2007-01-01T23:59:59.000Z

346

Steady-state and equilibrium vortex configurations, transitions, and evolution in a mesoscopic superconducting cylinder  

E-Print Network (OSTI)

that the system passes through nearly metastable intermediate configurations while seeking the final minimum-energy steady state consistent with the square symmetry of the sample. An efficient scheme to determine the equilibrium vortex configuration in a...

Kim, S.; Hu, Chia-Ren; Andrews, MJ.

2004-01-01T23:59:59.000Z

347

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...

Kim, Kyu-Sup

2012-06-07T23:59:59.000Z

348

MEC E 638 VORTEX FLOWS Winter 2014 LARGE-SCALE STRUCTURES IN TURBULENCE PROF L. SIGURDSON  

E-Print Network (OSTI)

to find the characteristic vortex structures; to read the literature, nomenclature, terminology. TOPICS: Professor Lorenz Sigurdson, 5-1B Mech Eng Bldg, lorenz@ualberta.ca, http://websrv.mece.ualberta.ca/intranet

Flynn, Morris R.

349

Visualization of Intricate Flow Structures for Vortex Breakdown Analysis Xavier Tricoche  

E-Print Network (OSTI)

Hansen University of Utah Figure 1: Vortex breakdown bubble in numerical simulation of a cylindrical to study their impact on flight stability. Yet, to fully exploit the huge amount of information contained

Utah, University of

350

Annular Vortex Generation for Inertial Fusion Energy Beam-Line Protection  

SciTech Connect

The use of swirling annular vortex flow inside beam entrance tubes can protect beam-line structural materials in chambers for heavy-ion inertial fusion energy (IFE) applications. An annular wall jet, or vortex tube, is generated by injecting liquid tangent to the inner surface of a tube wall with both axially and azimuthally directed velocity components. A layer of liquid then lines the beam tube wall, which may improve the effectiveness of neutron shielding, and condenses and removes vaporized coolant that may enter the beam tubes. Vortex tubes have been constructed and tested with a thickness of three-tenths the pipe radius. Analysis of the flow is given, along with experimental examples of vortex tube fluid mechanics and an estimate of the layer thickness, based on simple mass conservation considerations.

Pemberton, Steven J.; Abbott, Ryan P.; Peterson, Per F. [University of California (United States)

2003-05-15T23:59:59.000Z

351

E-Print Network 3.0 - alternative magnetic fields Sample Search...  

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

the interface between two immiscible liquids and energized by an alternating magnetic field. Depending... on the frequency and amplitude of magnetic field, a variety of dynamic...

352

Effect of a surface boundary layer on an intensifying, downward-propagating vortex  

E-Print Network (OSTI)

EFFECT OF A SURFACE BOUNDARY LAYER ON AN INTENSIFYING, DOWNWARD-PROPAGATING VORTEX A Thesis by VINCENT TUNSTALL WOOD Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER... OF SCIENCE May 1977 Major Subject: Meteorology EFFECT OF A SURFACE BOUNDARY LAYER ON AN INTENSIFYING, DOWNWARD-PROPAGATING VORTEX A Thesis by VINCENT TUNSTALL WOOD Approved as to style and content by: (Chairman of Committee) (Head of Department...

Wood, Vincent Tunstall

2012-06-07T23:59:59.000Z

353

Explicit mean-field radius for nearly parallel vortex filaments in statistical equilibrium  

E-Print Network (OSTI)

Geophysical research has focused on flows, such as ocean currents, as two dimensional. Two dimensional point or blob vortex models have the advantage of having a Hamiltonian, whereas 3D vortex filament or tube systems do not necessarily have one, although they do have action functionals. On the other hand, certain classes of 3D vortex models called nearly parallel vortex filament models do have a Hamiltonian and are more accurate descriptions of geophysical and atmospheric flows than purely 2D models, especially at smaller scales. In these ``quasi-2D'' models we replace 2D point vortices with vortex filaments that are very straight and nearly parallel but have Brownian variations along their lengths due to local self-induction. When very straight, quasi-2D filaments are expected to have virtually the same planar density distributions as 2D models. An open problem is when quasi-2D model statistics behave differently than those of the related 2D system and how this difference is manifested. In this paper we study the nearly parallel vortex filament model of Klein, Majda, Damodaran in statistical equilibrium. We are able to obtain a free-energy functional for the system in a non-extensive thermodynamic limit that is a function of the mean square vortex position $R^2$ and solve \\emph{explicitly} for $R^2$. Such an explicit formula has never been obtained for a non-2D model. We compare the results of our formula to a 2-D formula of \\cite{Lim:2005} and show qualitatively different behavior even when we disallow vortex braiding. We further confirm our results using Path Integral Monte Carlo (Ceperley (1995)) \\emph{without} permutations and that the Klein, Majda, Damodaran model's asymptotic assumptions \\emph{are valid} for parameters where these deviations occur.

Timothy D. Andersen; Chjan C. Lim

2006-11-19T23:59:59.000Z

354

Journal of Magnetism and Magnetic Materials 293 (2005) 578583 Theoretical comparison of magnetic and hydrodynamic  

E-Print Network (OSTI)

Ã?, Mikkel Fougt Hansen, Henrik Bruus MIC--Department of Micro and Nanotechnology, Technical University). #12;inhomogeneous magnetic field created by micro- structures that are magnetized by either electro wish to highlight the importance of hydro- dynamic interactions in connection with bead capturing

355

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

356

Model for characterization of a vortex pair formed by shock passage over a light-gas inhomogeneity  

SciTech Connect

This work investigates the two-dimensional flow of a shock wave over a circular light-gas inhomogeneity in a channel with finite width. The pressure gradient from the shock wave interacts with the density gradient at the edge of the inhomogeneity to deposit vorticity around the perimeter, and the structure rolls up into a pair of counter-rotating vortices. The aim of this study is to develop an understanding of the scaling laws for the flow field produced by this interaction at times long after the passage of the shock across the inhomogeneity. Numerical simulations are performed for various initial conditions and the results are used to guide the development of relatively simple algebraic models that characterize the dynamics of the vortex pair, and that allow extrapolation of the numerical results to conditions more nearly of interest in practical situations. The models are not derived directly from the equations of motion but depend on these equations and on intuition guided by the numerical results. Agreement between simulations and models is generally good except for a vortex-spacing model which is less satisfactory. A practical application of this shock-induced vortical flow is rapid and efficient mixing of fuel and oxidizer in a SCRAMJET combustion chamber. One possible injector design uses the interaction of an oblique shock wave with a jet of light fuel to generate vorticity which stirs and mixes the two fluids and lifts the burning jet away from the combustor wall. Marble proposed an analogy between this three-dimensional steady flow and the two-dimensional unsteady problem of the present investigation. Comparison is made between closely corresponding three-dimensional steady and two-dimensional unsteady flows, and a mathematical description of Marble`s analogy is proposed. 17 refs.

Yang, J.; Kubota, T.; Zukoski, E.E. [California Inst of Technology, Pasadena, CA (United States)

1994-01-01T23:59:59.000Z

357

Vortex-lattice activation energy deduced from irreversibility lines for (PrBa2Cu3-xGaxO7)M/(YBa2Cu3O7)N superlattices  

Science Journals Connector (OSTI)

The activation energy of the vortex structure in high anisotropic (PrBa2Cu3-xGaxO7)M/(YBa2Cu3O7)N superlattices with a layer thickness of the superconductor in the range 1.2–4.8 nm and with no Josephson coupling between the YBa2Cu3O7 elementary layers has been deduced from irreversibility lines Tirr(H). The activation energy is proportional to the thickness of the elementary YBa2Cu3O7 layer and to the logarithm of the field H, whereas it follows a TAFF behavior for a YBa2Cu3O7 single film. The origin of the activation energy is discussed in light of recent theories on vortex dynamic. The anisotropies deduced from both Tirr(H) and the Kosterlitz-Thouless analysis of the resistive transition are found to be strongly correlated.

D. Ravelosona, J. P. Contour, and N. Bontemps

2000-03-01T23:59:59.000Z

358

Magnetism.1  

Science Journals Connector (OSTI)

... each complete magnets with a pair of poles. The general character of the earth's magnetism has long been known—that the earth behaves with regard to magnets as though it ... and that these poles have a slow secular motion. For many years the earth's magnetism has been the subject of careful study by the most powerful minds. Gauss organized ...

1890-01-16T23:59:59.000Z

359

Magnetic catalysis in flavored ABJM  

E-Print Network (OSTI)

We study the magnetic catalysis of chiral symmetry breaking in the ABJM Chern-Simons matter theory with unquenched flavors in the Veneziano limit. We consider a magnetized D6-brane probe in the background of a flavored black hole which includes the backreaction of massless smeared flavors in the ABJM geometry. We find a holographic realization for the running of the quark mass due to the dynamical flavors. We compute several thermodynamic quantities of the brane probe and analyze the effects of the dynamical quarks on the fundamental condensate and on the phase diagram of the model. The dynamical flavors have an interesting effect on the magnetic catalysis. At zero temperature and fixed magnetic field, the magnetic catalysis is suppressed for small bare quark masses whereas it is enhanced for large values of the mass. When the temperature is non-zero there is a critical magnetic field, above which the magnetic catalysis takes place. This critical magnetic field decreases with the number of flavors, which we interpret as an enhancement of the catalysis.

Niko Jokela; Alfonso V. Ramallo; Dimitrios Zoakos

2013-11-25T23:59:59.000Z

360

Vortex erosion and amalgamation in a new model of large scale flow on the sphere  

SciTech Connect

The pseudo-spectral methodology that is typically employed to simulate fluid flow in spherical geometry exhibits, among other limitations, a severe degradation of performance at high resolution. Finite element models based upon the application of multigrid methods may be designed so as to avoid this defect while also allowing for greater local control over the computational mesh. We describe herein the details of the mathematical methods that are required to implement such a computational structure and apply these methods to design a model based upon the two dimensional spherical barotropic vorticity equation, the simplest framework within which their viability may be tested. The model is thereafter employed in the analysis of two essentially inviscid nonlinear dynamical problems in order to provide proof of concept. The first of these test problems entails repeating a well known pseudospectral calculation of the erosion of a polar vortex under slow, quasi-steady, Rossby wave forcing at low zonal wavenumber. The second test problem concerns the simulation of the nonlinear development of the instability of a zonal shear band into a train of like signed vortices which subsequently amalgamate through the nonlinear pairing interaction. Results of these test calculations, as well as those based upon additional analyses that we discuss herein, demonstrate that the performance of our initial methodology meets the basic criteria of fluid flow simulation. This suggests, on the basis of theoretical efficiency, that optimized versions could eventually compete with the large production codes which are in operation today. Our future intent is to further develop this computational structure so as to create a new class of three-dimensional general circulation models that may be employed in a wide variety of astrophysical and atmosphere-ocean applications. 25 refs., 11 figs.

Stuhne, G.R.; Peltier, W.R. [Univ. of Toronto, Ontario (Canada)] [Univ. of Toronto, Ontario (Canada)

1996-10-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

Earth’s magnetism  

Science Journals Connector (OSTI)

Earth’s magnetism, geomagnetism, terrestrial magnetism [The magnetism of the Earth] ? Erdmagnetismus m, Geomagnetismus

2014-08-01T23:59:59.000Z

362

Increasing liquid hydrocarbon recovery from natural gas: Evaluation of the vortex-tube device  

SciTech Connect

The vortex-tube device provides a useful addition to the range of equipment available to the gas industry. It has been shown that the use of vortex-tube equipment permits improved separation in comparison with a Joule-Thomson system, without entering into the cost and complexity of a true isentropic system such as a turbo-expander unit. The comparative advantage of the vortex tube depends upon the inlet conditions of the gas and the pressure drop that is available. An optimum pressure drop of 25--35% of the inlet gas pressure has been confirmed in practice. Although not yet tested on operating plant, it is expected that a loss of performance of vortex-tube units will occur for inlet liquid-to-gas ratios of greater than 20%. Units with up to 5% liquid at the inlet have been successfully operated showing that a single phase gas at the unit inlet is not essential. It is expected that future application of vortex tube units will be concentrated where performance improvements over Joule-Thomson units, at low capital cost, are required.

Hajdik, B. [CBS Engineering, Houston, TX (United States); Steinle, J. [BEB Erdoel and Erdgas GmbH, Hannover (Germany); Lorey, M. [Filtan Analgenbau GmbH, Langenselbold (Germany); Thomas, K. [Falk and Thomas Engineering GmbH, Wettenberg (Germany)

1997-12-31T23:59:59.000Z

363

Turbulence may be key to "fast magnetic reconnection" mystery  

E-Print Network (OSTI)

, 1970) showed that magnetic field lines are "frozen" into a perfectly conducting (or ideal) plasma implication of Alfven's Theorem is that magnetic field lines cannot break and change connections. If magnetic astrophysical situations is essentially fluid-dynamic, where magnetic field lines break and reconnect over fast

364

Numerical Simulation of the Meso-? Scale Structure and Evolution of the 1977 Johnstown Flood. Part II: Inertially Stable Warm-Core Vortex and the Mesoscale Convective Complex  

Science Journals Connector (OSTI)

A mesoscale warm-core vortex associated with the mesoscale convective complex (MCC) that produced the 1977 Johnstown flood is examined using a three-dimensional nested-grid model simulation of the flood episode. In the simulation, the vortex ...

Da-Lin Zhang; J. Michael Fritsch

1987-09-01T23:59:59.000Z

365

Fabrication and characterization of nanostructured magnetic particles for applications in data storage  

E-Print Network (OSTI)

Arrays of nanostructured magnetic particles ('nanomagnets') have potential applications in ultra-high-density data storage devices and dynamic magnetic memories, and are model systems for the study of magnetic phenomena ...

Farhoud, Maya S. (Maya Sami)

2001-01-01T23:59:59.000Z

366

Brett Parker | Superconducting Magnet Division  

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

Brett Parker Brett Parker Recent Presentations "BNL Direct Wind Magnets," (pdf) presentation dedicated to the memory of Pat Thompson given at the 22nd Magnet Technology Conference (MT22), September 11 - 16, 2011, Marseille, France A Review of BNL Direct-Wind Superconducting IR Magnet Experience, (pdf) presented at the 30th Advanced ICFA Beam Dynamics Workshop on High Luminosity e+e- Collisions, October 13 - 16, 2003, Stanford, California The Serpentine Coil Design for BEPC-II Superconducting IR Magnets, (pdf) presented at the "Mini-Workshop on BEPC-II IR Design", January 12 - 16, 2004, Beijing, P.R. China Ma nufacture of a Superconducting Octupole Magnet for the ALPHA Experiment at CERN using the Direct Wind Machine Presentations Prior to 2004 Superconducting Final Focus Magnet Issues (pdf), presented at

367

Joule heating induced by vortex motion in a type-II superconductor Z. L. Xiao and E. Y. Andrei  

E-Print Network (OSTI)

Joule heating induced by vortex motion in a type-II superconductor Z. L. Xiao and E. Y. Andrei-II superconductor due to Joule heating induced by vortex motion. The effect of Joule heating is detected s duration, where the Joule heating is negligible and saturates, respectively. The thermometry is based

Andrei, Eva Y.

368

Counter-rotating vortex patches in shear: a model of the effect of wind shear on aircraft trailing vortices  

Science Journals Connector (OSTI)

...significantly a following passenger-containing aircraft and cause an accident. For example, the vortex wake of a Boeing 747 can rotate a Boeing 737 through 45 . This problem is called the trailing-vortex hazard, and since the trailing vortices can...

2002-01-01T23:59:59.000Z

369

Slowing of vortex rings by development of Kelvin waves Robert E. Hershberger, Diogo Bolster, and Russell J. Donnelly*  

E-Print Network (OSTI)

of existence, their duration a problem of stability and if there are several we have a problem of vortex mecha- nism is that the bubble loses impulse as the radius of the ring grows due to viscous decay of circulation 6 . A further theory suggests that the vortex bubble the ambient fluid car- ried along

Bolster, Diogo

370

Modern Magnetism  

Science Journals Connector (OSTI)

... BATES‘S "Modern Magnetism", first published in 1939, is widely appreciated as a general survey in which ... grateful to the author for collecting together so much interesting information about recent work in magnetism. ...

E. C. S.

1948-06-05T23:59:59.000Z

371

Reduction of vortex induced forces and motion through surface roughness control  

DOE Patents (OSTI)

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 decrease/suppress Vortex Induced Forces and Motion. Suppression is required when fluid-structure interaction becomes destructive as in VIM of flexible cylinders or rigid cylinders on elastic support, such as underwater pipelines, marine risers, tubes in heat exchangers, nuclear fuel rods, cooling towers, SPAR offshore platforms.

Bernitsas, Michael M; Raghavan, Kamaldev

2014-04-01T23:59:59.000Z

372

Experimental study of vortex generators effects on low Reynolds number airfoils in turbulent flow  

Science Journals Connector (OSTI)

In the present work, we study the aerodynamic effects of triangular vortex generators, as passive flow control devices, placed on the upper surface of an airfoil submitted to a low Reynolds number turbulent flow. In the experiments, different configurations of those devices have been studied. An Eppler 387 airfoil was used. The tests were performed in a turbulent boundary layer wind tunnel using a two component aerodynamic balance and flow visualisation systems. Turbulent flow characterisation was made by means of hot wire anemometry. Calculations of local turbulent intensity as well as temporal and spatial turbulent scales were made. Vortex generators were located at 10% and 20% of the airfoil chord from the leading edge, modifying its angle of incidence refereed to the free stream. The results show changes in the aerodynamic section coefficients, C1, Cd and C1, for the different vortex generator configurations. Neither hysteresis effects, nor leading edge bubbles were found in the experiments.

Juan Sebastián Delnero; Julio Marañon Di Leo; Mauricio Ezequiel Camocardi; Mariano A. Martinez; Jorge L. Colman Lerner

2012-01-01T23:59:59.000Z

373

Migratory magnetism  

Science Journals Connector (OSTI)

... in tune with the Earth's magnetic field. But how, exactly, do creatures sense magnetism? This is one of the most intriguing questions in modern biology - and also ... move preferentially in a north-south direction. This finding hints at the possible influence of magnetism on their movements. ...

Henry Gee

1999-10-06T23:59:59.000Z

374

Phase-locking of driven vortex lattices with transverse ac force and periodic pinning  

SciTech Connect

For a vortex lattice moving in a periodic array we show analytically and numerically that a new type of phase locking occurs in the presence of a longitudinal dc driving force and a transverse ac driving force. This phase locking is distinct from the Shapiro step phase locking found with longitudinal ac drives. We show that an increase in critical current and a fundamental phase-locked step width scale with the square of the driving ac amplitude. Our results should carry over to other systems such as vortex motion in Josephson-junction arrays.

Reichhardt, Charles; Kolton, Alejandro B.; Dominguez, Daniel; Gronbech-Jensen, Niels

2001-10-01T23:59:59.000Z

375

The effects of a jet on vortex breakdown over a sharp leading-edge delta wing  

E-Print Network (OSTI)

THE EFFECTS OF A JET ON VORTEX BREAKDOWN OVER A SHARP LEADING-EDGE DELTA WING A Thesis Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1985... Major Subject: Aerospace Engineering THE EFFECTS OF A JET ON VORTEX BREAKDOWN OVER A SHARP LEADING-EDGE DELTA WING A Thesis by IAN KENNETH MAYNARD Approved as to style and content by: Cyrus Ostowar (Chairman of Committee) Stan J Miley (M er...

Maynard, Ian Kenneth

2012-06-07T23:59:59.000Z

376

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

E-Print Network (OSTI)

in Fig. IV.1(a) is electrical resistivity ? vs temperature Tof the electrical resistivity, d?/dT vs T for various valuesof the electrical re- sistivity d?/dT vs T . Below the lower

Taylor, Benjamin Jeremy

2006-01-01T23:59:59.000Z

377

Vortex-Pair Dynamics in Anisotropic Bistable Media: A Kinematic Approach Aric Hagberg1  

E-Print Network (OSTI)

Alamos, New Mexico 87545, USA 2 Department of Solar Energy and Environmental Physics, BIDR, Ben Gurion

Hagberg, Aric

378

Physics Reports 355 (2001) 235334 Quantum phase transitions and vortex dynamics in  

E-Print Network (OSTI)

Contents 1. Introduction 237 1.1. Josephson-junction arrays 237 1.2. Phase-number relation 238 1.3. Structure of the review 239 2. Quantum phase transitions 240 2.1. The model of a Josephson-junction array currents 313 4.2. The quantum Hall e ect 316 4.3. Quantum computation with Josephson junctions 317

379

Probabilistic Evaluation of the Dynamics and Predictability of the Mesoscale Convective Vortex of 1013 June 2003  

E-Print Network (OSTI)

National Center for Atmospheric Research,* Boulder, Colorado (Manuscript received 14 September 2005 have been linked to extreme rainfall events, such as the Johnstown, Pennsylvania, flood of 1977 (Bosart

Meng, Zhiyong

380

Mesoscopic structuring and dynamics of alcohol/water solutions probed by Terahertz Time-Domain Spectroscopy and Pulsed Field Gradient Nuclear Magnetic Resonance  

E-Print Network (OSTI)

in the structure of alcohol/water mixtures. Taking aqueous ethanol as a representative example, excess enthalpy, heat capacity, diffusivity, and viscosity all exhibit maxima or minima at ?15?20 mol %;12,16,20?23 this is attributable to Received: March 20, 2014... dielectric spectroscopy and the results were compared to femtosecond infrared pump? probe studies. By investigating a range of concentrations of aqueous tetramethylurea solutions it was found that the dynamics of the water molecules in close vicinity...

Li, Ruoyu; D'Agostino, Carmine; McGregor, James; Mantle, Michael D.; Zeitler, J. Axel; Gladden, Lynn F.

2014-08-12T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

Magnetic Testing of Bonded Magnets  

Science Journals Connector (OSTI)

Many techniques exist to characterize the magnetic properties of bonded magnets. We will review the common and not so common techniques in use, with emphasis on the advantages and disadvantages of each one, an...

S. R. Trout

2003-01-01T23:59:59.000Z

382

Magnetic neutron scattering (invited)  

Science Journals Connector (OSTI)

The application of neutron scattering techniques to magnetic problems is reviewed. We will first discuss diffraction techniques used to solve magnetic structures as well as to measure magnetic form factors order parameters critical phenomena and the scattering from low?dimensional systems. We will also discuss inelastic scattering techniques including polarized beam methods utilized to determine the spin dynamics of various materials. Information will be provided about the types of spectrometers available at the user?oriented national facilities located at Argonne National Laboratory Brookhaven National Laboratory Los Alamos National Laboratory The National Institute of Standards and Technology and Oak Ridge National Laboratory as well as the spectrometers at the Missouri University Research Reactor.

J. W. Lynn

1994-01-01T23:59:59.000Z

383

Dynamics of quantum spin liquid and spin solid phases in IPA-CuCl3 under an applied magnetic field studied with neutron scattering  

SciTech Connect

Inelastic and elastic neutron scattering is used to study spin correlations in the quasi-one-dimensional quantum antiferromagnet IPA-CuCl3 in strong applied magnetic fields. A condensation of magnons and commensurate transverse long-range ordering is observe at a critical field Hc=9.5 T. The field dependencies of the energies and polarizations of all magnon branches are investigated both below and above the transition point. Their dispersion is measured across the entire one-dimensional Brillouin zone in magnetic fields up to 14 T. The critical wave vector of magnon spectrum truncation Masuda et al., Phys. Rev. Lett. 96, 047210 2006 is found to shift from hc0,35 at HHC to hc=0.25 for HHC. A drastic reduction of magnon bandwidths in the ordered phase Garlea et al., Phys. Rev. Lett. 98, 167202 2007 is observed and studied in detail. New features of the spectrum, presumably related to this bandwidth collapse, are observed just above the transition field.

Zheludev, Andrey I [ORNL; Garlea, Vasile O [ORNL; Masuda, T. [Yokohama City University, Japan; Manaka, H. [Kagoshima University, Kagoshima JAPAN; Regnault, L.-P. [CEA, Grenoble, France; Ressouche, E. [CEA, Grenoble, France; Grenier, B. [CEA, Grenoble, France; Chung, J.-H. [National Institute of Standards and Technology (NIST); Qiu, Y. [National Institute of Standards and Technology (NIST); Habicht, Klaus [Hahn-Meitner Institut, Berlin, Germany; Kiefer, K. [Hahn-Meitner Institut, Berlin, Germany; Boehm, Martin [Institut Laue-Langevin (ILL)

2007-01-01T23:59:59.000Z

384

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.

385

THz Dynamic Nuclear Polarization NMR  

E-Print Network (OSTI)

Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) spectroscopy by using high frequency microwaves to transfer the polarization of the electrons to the nuclear spins. The ...

Nanni, Emilio Alessandro

386

HAWT performance with dynamic stall  

SciTech Connect

In this report we calculated the effects of flow nonuniformities (wing shear, tower wake, yaw, and large-scale turbulence) on the performance of a horizontal axis wind turbine, accounting for dynamic stall. We modified the PROP program to incorporate and compare these effects with the uniform flow case. The MIT model, which predicts dynamic lift coefficients substantially higher than the static maximum values and includes a crude model of the vortex roll-off phenomenon, represented dynamic stall. As associated model for drag was also used. The dynamic stall model was tested against experimental data for three typical reduced frequencies. Good instantaneous correlation was obtained. The effects of nonuniformities with and without the dynamic stall were calculated using the Westinghouse Mod O and Enertech 44/25 turbines. Modeling the dynamic stall has little effect on performance. Furthermore, the performance with nonuniform flow differed only slightly from the uniform flow case. Thus the now PROP model provides a powerful general capability to handle nonuniform flows.

Hibbs, B.D.

1986-02-01T23:59:59.000Z

387

Correlated vortex pinning in slightly orthorhombic twinned Ba(Fe1-xCox)2As2 single crystals: Possible shift of the vortex-glass/liquid transition  

SciTech Connect

The interest in twin-boundary (TB) planes as a source of vortex pinning has been recently renewed with the discovery of the new iron-arsenide pnictide superconductors. In the family of compounds Ba(Fe1-xCox)2As2 a structural transition from a tetragonal to orthorhombic lattice takes place for compounds with xvortex cores. In this work we investigate the changes in anisotropy produced by subtle differences in the Co doping level, in the neighborhood of the structural transition, in good-quality single crystals. Using a scaling approach we are able to determine the angular regions where correlated or uncorrelated disorder prevails. In the tetragonal samples (x>xcr) there is no twinning and we find good agreement with the expected scaling function under uncorrelated disorder, with small anisotropy values similar to those reported in the literature. We show that in the orthorhombic samples (xvortex liquid-glass transition temperature.

Bermudez, M. Marziali [Universidad de Buenos Aires; Pasquini, G. [Universidad de Buenos Aires; Budko, Sergey L. [Ames Laboratory; Canfield, Paul C. [Ames Laboratory

2013-02-28T23:59:59.000Z

388

Tropical cyclone genesis efficiency: mid-level versus bottom vortex Xuyang Ge and Tim Li  

E-Print Network (OSTI)

;4 1. Introduction Tropical cyclone (TC) genesis is the least understood phase in a TC life cycle is cyclogenesis in an environment with a mid-level vortex (EMV). An analysis of the WNP TC genesis in 2000 the QuikSCAT-derived surface wind observations, there was no sign

Li, Tim

389

DETECTION OF VORTEX TUBES IN SOLAR GRANULATION FROM OBSERVATIONS WITH SUNRISE  

SciTech Connect

We have investigated a time series of continuum intensity maps and corresponding Dopplergrams of granulation in a very quiet solar region at the disk center, recorded with the Imaging Magnetograph eXperiment (IMaX) on board the balloon-borne solar observatory SUNRISE. We find that granules frequently show substructure in the form of lanes composed of a leading bright rim and a trailing dark edge, which move together from the boundary of a granule into the granule itself. We find strikingly similar events in synthesized intensity maps from an ab initio numerical simulation of solar surface convection. From cross sections through the computational domain of the simulation, we conclude that these granular lanes are the visible signature of (horizontally oriented) vortex tubes. The characteristic optical appearance of vortex tubes at the solar surface is explained. We propose that the observed vortex tubes may represent only the large-scale end of a hierarchy of vortex tubes existing near the solar surface.

Steiner, O.; Franz, M.; Bello Gonzalez, N.; Nutto, Ch.; Rezaei, R.; Schmidt, W. [Kiepenheuer-Institut fuer Sonnenphysik, Schoeneckstrasse 6, 79104 Freiburg (Germany); Martinez Pillet, V.; Bonet Navarro, J. A. [Instituto de Astrofisica de Canarias, 38200, La Laguna, Tenerife (Spain); Del Toro Iniesta, J. C. [Instituto de Astrofisica de Andalucia (CSIC), Apdo. de Correos 3004, 18080 Granada (Spain); Domingo, V. [Grupo de Astronomia y Ciencias del Espacio, Universidad de Valencia, 46980 Paterna, Valencia (Spain); Solanki, S. K.; Barthol, P.; Gandorfer, A. [Max-Planck-Institut fuer Sonnensystemforschung, 37191 Katlenburg-Lindau (Germany); Knoelker, M., E-mail: steiner@kis.uni-freiburg.d [High Altitude Observatory, National Center for Atmospheric Research (NCAR), Boulder, CO 80307-3000 (United States)

2010-11-10T23:59:59.000Z

390

ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 27, NO. 2, 2010, 243252 Mesoscale Barotropic Instability of Vortex Rossby  

E-Print Network (OSTI)

ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 27, NO. 2, 2010, 243­252 Mesoscale Barotropic Instability of Vortex Rossby Waves in Tropical Cyclones ZHONG Wei1 ( Í), LU Han-Cheng1 (ö ), and Da-Lin ZHANG2 1 Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101 2 Department

Zhang, Da-Lin

391

Sediment resuspension and erosion by vortex rings R. J. Munro,1,a  

E-Print Network (OSTI)

Sediment resuspension and erosion by vortex rings R. J. Munro,1,a N. Bethke,2 and S. B. Dalziel2 1; accepted 26 January 2009; published online 8 April 2009 Particle resuspension and erosion induced-ring propagation speed. The critical conditions for resuspension whereby particles are only just resuspended were

Dalziel, Stuart

392

Particle resuspension by an impacting vortex ring RICK J. MUNRO & STUART B. DALZIEL  

E-Print Network (OSTI)

Particle resuspension by an impacting vortex ring RICK J. MUNRO & STUART B. DALZIEL Department results from a set of visualization experiments conducted to analyse the hydrodynamic resuspension of particles from a thick horizontal sediment layer. The mechanism employed to produce the resuspension

Dalziel, Stuart

393

Tip Vortex Field Resolution Using an Adaptive Dual-Mesh Computational Nathan Hariharan  

E-Print Network (OSTI)

for the aforementioned unsteady, vortical fields. 1. Introduction 1.1 Background Vortical wakes introduce important AMR in an unstructured Euler solver. Potsdam[3] also applied unstructured AMR to wind turbine wake1 Tip Vortex Field Resolution Using an Adaptive Dual-Mesh Computational Paradigm Nathan Hariharan

Steffen, Michael

394

First-order disorder-driven transition and inverse melting of the vortex lattice  

E-Print Network (OSTI)

`inverse' melting behavior. � 2001 Published by Elsevier Science B.V. Keywords: Type-II superconductivity-order transition (FOT) [1±5] whereas at low temperatures the ordered vortex lattice transforms into a disordered open questions in the phase diagram of HTS is the thermodynamic nature of the disorder-dri- ven

Zeldov, Eli

395

Computational Analysis of a Tip Vortex Structure Shed from a Bioinspired Blade  

E-Print Network (OSTI)

design for this purpose. Different rotor blade designs and relevant insect wings are under study Computational Analysis of a Tip Vortex Structure Shed from a Bioinspired Blade Sebastian was generated with SolidWorks CAD software from measurements performed on a wing sample obtained from

Maccabe, Barney

396

VIVDR -Vortex-induced vibration data repository An overview of available riser datasets  

E-Print Network (OSTI)

VIVDR - Vortex-induced vibration data repository An overview of available riser datasets http://oe.mit.edu/VIV H. Mukundan and M. Triantafyllou 20 April 2008 #12;NDP 38m long riser model datasets #12;33 q Rig q Tension applied through spring-supported clump weights NDP 38m long riser model datasets

397

2094 OPTICS LETTERS / Vol. 28, No. 21 / November 1, 2003 Fundamental and vortex solitons in a  

E-Print Network (OSTI)

2094 OPTICS LETTERS / Vol. 28, No. 21 / November 1, 2003 Fundamental and vortex solitons in a two-dimensional optical lattice Jianke Yang Department of Mathematics and Statistics, University of Vermont, Burlington-dimensional optically induced waveguide array are reported. In the strong localization regime the fundamental soliton

Yang, Jianke

398

Effect of asymmetric axial strain on the behavior of the juncture vortex system  

E-Print Network (OSTI)

The objective of this research was to investigate the behavior of the vortex formed in a wing-body juncture in a water tunnel flow. The wing-body juncture was created by mounting a symmetrical airfoil with an elliptical leading edge normal to a flat...

Trosper, Jeffrey Randall

2012-06-07T23:59:59.000Z

399

Nanogenerator as an active sensor for vortex capture and ambient wind-velocity detection  

E-Print Network (OSTI)

and mechanical (wind, water flow, vibration, friction and body movement) energies are common in the ambientNanogenerator as an active sensor for vortex capture and ambient wind-velocity detection Rui Zhang principle, ambient wind-speed measurements with the NG are demonstrated. Due to the simple structure, high

Wang, Zhong L.

400

Acoustic emission from magnetic flux tubes in the solar network  

E-Print Network (OSTI)

We present the results of three-dimensional numerical simulations to investigate the excitation of waves in the magnetic network of the Sun due to footpoint motions of a magnetic flux tube. We consider motions that typically mimic granular buffeting and vortex flows and implement them as driving motions at the base of the flux tube. The driving motions generates various MHD modes within the flux tube and acoustic waves in the ambient medium. The response of the upper atmosphere to the underlying photospheric motion and the role of the flux tube in channeling the waves is investigated. We compute the acoustic energy flux in the various wave modes across different boundary layers defined by the plasma and magnetic field parameters and examine the observational implications for chromospheric and coronal heating.

Vigeesh, G

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

Magnetic Field Lines in Fusion Plasmas  

Science Journals Connector (OSTI)

Study of mappings as a part of Hamiltonian dynamics of magnetic field lines in plasmas were initiated by the research...1.... Actually, a fusion research in early sixties gave a huge impact on the development of ...

Sadrilla S. Abdullaev

2006-01-01T23:59:59.000Z

402

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

403

Magnetic shielding  

DOE Patents (OSTI)

A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient magnetic field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines. 3 figs.

Kerns, J.A.; Stone, R.R.; Fabyan, J.

1987-10-06T23:59:59.000Z

404

Magnetic shielding  

DOE Patents (OSTI)

A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient magnetic field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines.

Kerns, John A. (Livermore, CA); Stone, Roger R. (Walnut Creek, CA); Fabyan, Joseph (Livermore, CA)

1987-01-01T23:59:59.000Z

405

Strange Magnetism  

E-Print Network (OSTI)

We present an analytic and parameter-free expression for the momentum dependence of the strange magnetic form factor of the nucleon and its corresponding radius which has been derived in Heavy Baryon Chiral Perturbation Theory. We also discuss a model-independent relation between the isoscalar magnetic and the strange magnetic form factors of the nucleon based on chiral symmetry and SU(3) only. These limites are used to derive bounds on the strange magnetic moment of the proton from the recent measurement by the SAMPLE collaboration.

Thomas R. Hemmert; Ulf-G. Meissner; Sven Steininger

1998-11-09T23:59:59.000Z

406

Optical Magnetism  

Science Journals Connector (OSTI)

Magnetic dipole radiation one fourth as intense as electric dipole radiation, as well as a novel nonlinear magneto-optical effect are reported in dielectric media.

Oliveira, Samuel L; Rand, Stephen C

407

Magnetic Field Safety Magnetic Field Safety  

E-Print Network (OSTI)

Magnetic Field Safety Training #12;Magnetic Field Safety Strong Magnetic Fields exist around energized magnets. High magnetic fields alone are a recognized hazard only for personnel with certain medical conditions such as pacemakers, magnetic implants, or embedded shrapnel. In addition, high magnetic

McQuade, D. Tyler

408

Dynamics of strings between walls  

SciTech Connect

Configurations of vortex strings stretched between or ending on domain walls were previously found to be 1/4 Bogomol'nyi-Prasad-Sommerfield (BPS) states in N=2 supersymmetric gauge theories in 3+1 dimensions. Among zero modes of string positions, the center of mass of strings in each region between two adjacent domain walls is shown to be non-normalizable whereas the rests are normalizable. We study dynamics of vortex strings stretched between separated domain walls by using two methods, the moduli space (geodesic) approximation of full 1/4 BPS states and the charged particle approximation for string end points in the wall effective action. In the first method we explicitly obtain the effective Lagrangian in the strong coupling limit, which is written in terms of hypergeometric functions, and find the 90 deg. scattering for head-on collision. In the second method the domain wall effective action is assumed to be U(1){sup N} gauge theory, and we find a good agreement between two methods for well-separated strings.

Eto, Minoru [INFN, Sezione di Pisa, Largo Pontecorvo, 3, Ed. C, 56127 Pisa (Italy); Department of Physics, University of Pisa Largo Pontecorvo, 3, Ed. C, 56127 Pisa (Italy); Fujimori, Toshiaki; Nagashima, Takayuki [Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551 (Japan); Nitta, Muneto [Department of Physics, Keio University, Hiyoshi, Yokohama, Kanagawa 223-8521 (Japan); Ohashi, Keisuke [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, CB3 0WA (United Kingdom); Sakai, Norisuke [Department of Mathematics, Tokyo Woman's Christian University, Tokyo 167-8585 (Japan)

2009-02-15T23:59:59.000Z

409

Magnetic Field Safety Training  

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

Safety Training Magnetic Field Safety Strong Magnetic Fields exist around energized magnets. High magnetic fields alone are a recognized hazard only for personnel with certain...

410

Methods for characterizing magnetic footprints of perpendicular magnetic recording writer heads  

SciTech Connect

In this work, the magnetic footprints, along with some of its dynamic features in recording process, of perpendicular magnetic recording writer heads have been characterized by using three different techniques. Those techniques are the spin-stand stationary footprint technique, the spin-stand dynamic footprint technique, and the coherent writing technique combined with magnetic force microscope imaging method. The characteristics of those techniques have been compared to one another. It was found experimentally that the spin-stand stationary method could not precisely catch some peculiar recording dynamics of the write heads in certain conditions. The advantages and disadvantages among all those techniques are also examined and discussed in detail.

Li, Shaoping, E-mail: shaoping.li@wdc.com; Lin, Ed; George, Zach; Terrill, Dave; Mendez, H.; Santucci, J.; Yie, Derek [Western Digital Corp., 44100 Osgood Road, Fremont, California 94539 (United States)

2014-05-07T23:59:59.000Z

411

Magnetic insulation  

Science Journals Connector (OSTI)

... by Winterberg1, led me to look into the background of the idea of 'magnetic insulation'. The purpose of this letter is to point out that the scheme described in ... were presented earlier in a longer article2. In that article he suggested that 'magnetic insulation' might make possible a transformer for 109 V. A year later the same objections ...

JOHN P. BLEWETT

1974-06-28T23:59:59.000Z

412

Magnetism1  

Science Journals Connector (OSTI)

... is reached, the rate of diminution becomes very rapid indeed, until, finally, the magnetism of the iron disappears at the same time as for small forces. Instead of ... a lower maximum, and its rise is less rapid. The critical temperature at which magnetism disappears changes rapidly with the composition of the steel. For very soft charcoal iron ...

1890-01-23T23:59:59.000Z

413

Magnetism Group  

Science Journals Connector (OSTI)

... of the Institute of Physics and the Physical Society has announced the establishment of a Magnetism Group. The aim of the new Group is to further interest in ... Group. The aim of the new Group is to further interest in magnetism by holding regular discussion meetings and in other ways. It is intended that these ...

1965-09-04T23:59:59.000Z

414

Terrestrial Magnetism*  

Science Journals Connector (OSTI)

... A similar investigation of the effect of the moon's action on terrestrial magnetism requires a series of observations made at much less distant intervals than the monthly ones ... heat, from the central body of our system, or merely having its own inherent magnetism modified by solar action, then we must choose as our unit the lunation, or ...

1873-01-09T23:59:59.000Z

415

Terrestrial Magnetism*  

Science Journals Connector (OSTI)

... IN bringing before you this evening, gentlemen, the subject of terrestrial magnetism, it is not my intention to attempt to present you with an exhaustive paper ... clearly as I am able, what is the actual condition of our knowledge respecting the magnetism of the globe, and what the nature of its complex variations, without, however, ...

1873-01-02T23:59:59.000Z

416

Terrestrial Magnetism  

Science Journals Connector (OSTI)

... THE present activity of the department of terrestrial magnetism of the Carnegie Institution of Washington and the largeness of its future aims are alike ... a “progress report” which he contributes to the latest (March) number of Terrestrial Magnetism. The department, which has lately entered on its eleventh year, has under construetion ...

C. CHREE

1914-07-23T23:59:59.000Z

417

Remanent Magnetism  

Science Journals Connector (OSTI)

... STUDY of the natural remanent magnetism of rocks is becoming a familiar method for determining the direction of the Earth's ... the geomagnetic poles or of the continents themselves. An alternative use for measurements of remanent magnetism, namely, the determination of the temperature of formation of pyroclastic deposits, is described ...

1958-03-22T23:59:59.000Z

418

Magnetic shielding  

DOE Patents (OSTI)

A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines.

Kerns, J.A.; Stone, R.R.; Fabyan, J.

1985-02-12T23:59:59.000Z

419

Design of a scanning Josephson junction microscope for submicron-resolution magnetic imaging  

SciTech Connect

We describe a magnetic field scanning instrument designed to extend the spatial resolution of scanning superconducting quantum interference device microscopy into the submicron regime. This instrument, the scanning Josephson junction microscope, scans a single Josephson junction across the surface of a sample, detecting the local magnetic field by the modulation of the junction critical current. By using a submicron junction and a scanning tunneling microscope feedback system to maintain close proximity to the surface, magnetic field sensitivity of 10 {mu}G with a spatial resolution of 0.3 {mu}m should be attainable, opening up new opportunities for imaging vortex configurations and core structure in superconductors and magnetic domains in magnetic materials. {copyright} {ital 1999 American Institute of Physics.}

Plourde, B.L.; Van Harlingen, D.J. [Department of Physics, Science and Technology Center for Superconductivity, and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)] [Department of Physics, Science and Technology Center for Superconductivity, and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

1999-11-01T23:59:59.000Z

420

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

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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 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

422

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

Science Journals Connector (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

423

Dynamic Contrast-Enhanced Magnetic Resonance Imaging as a Predictor of Outcome in Head-and-Neck Squamous Cell Carcinoma Patients With Nodal Metastases  

SciTech Connect

Purpose: Dynamic contrast-enhanced MRI (DCE-MRI) can provide information regarding tumor perfusion and permeability and has shown prognostic value in certain tumors types. The goal of this study was to assess the prognostic value of pretreatment DCE-MRI in head and neck squamous cell carcinoma (HNSCC) patients with nodal disease undergoing chemoradiation therapy or surgery. Methods and Materials: Seventy-four patients with histologically proven squamous cell carcinoma and neck nodal metastases were eligible for the study. Pretreatment DCE-MRI was performed on a 1.5T MRI. Clinical follow-up was a minimum of 12 months. DCE-MRI data were analyzed using the Tofts model. DCE-MRI parameters were related to treatment outcome (progression-free survival [PFS] and overall survival [OS]). Patients were grouped as no evidence of disease (NED), alive with disease (AWD), dead with disease (DOD), or dead of other causes (DOC). Prognostic significance was assessed using the log-rank test for single variables and Cox proportional hazards regression for combinations of variables. Results: At last clinical follow-up, for Stage III, all 12 patients were NED. For Stage IV, 43 patients were NED, 4 were AWD, 11 were DOD, and 4 were DOC. K{sup trans} is volume transfer constant. In a stepwise Cox regression, skewness of K{sup trans} (volume transfer constant) was the strongest predictor for Stage IV patients (PFS and OS: p <0.001). Conclusion: Our study shows that skewness of K{sup trans} was the strongest predictor of PFS and OS in Stage IV HNSCC patients with nodal disease. This study suggests an important role for pretreatment DCE-MRI parameter K{sup trans} as a predictor of outcome in these patients.

Shukla-Dave, Amita, E-mail: davea@mskcc.org [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Lee, Nancy Y. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Jansen, Jacobus F.A. [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Thaler, Howard T. [Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Stambuk, Hilda E. [Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Fury, Matthew G. [Department of Medical Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Patel, Snehal G. [Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Moreira, Andre L. [Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Sherman, Eric [Department of Medical Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Karimi, Sasan [Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Wang, Ya [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Kraus, Dennis; Shah, Jatin P. [Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Pfister, David G. [Department of Medical Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); and others

2012-04-01T23:59:59.000Z

424

Motion of charged particles in ABC magnetic fields Alejandro Luque #  

E-Print Network (OSTI)

Motion of charged particles in ABC magnetic fields Alejandro Luque # Departament de Matemâ?? atica consequences of our study are the existence of confinement regions of charges near some magnetic lines, magnetic field, Hamiltonian dynamical system, el­ liptic equilibrium point, quasi­periodic solution

425

Linear chain magnetism  

Science Journals Connector (OSTI)

Linear chain magnetism ... A brief introduction to this concept, which is also called lower dimensional magnetism. ...

Richard L. Carlin

1991-01-01T23:59:59.000Z

426

Anisotropy and coherent vortex structures in planetary turbulence  

SciTech Connect

High-resolution numerical simulations were made of unforced, planetary-scale fluid dynamics. In particular, the simulation was based on the quasi-geostrophic equations for a Boussinesq fluid in a uniformly rotating and stably stratified environment, which is an idealization for large regions of either the atmosphere or ocean. The solutions show significant discrepancies from the long-standing theoretical prediction of isotropy. The discrepancies are associated with the self-organization of the flow into a large population of coherent vortices. Their chaotic interactions govern the subsequent evolution of the flow toward a final configuration that is nonturbulent.

McWilliams, J.C. (National Center for Atmospheric Research, Boulder, CO (United States)); Weiss, J.B. (Univ. of Colorado, Boulder, CO (United States)); Yavneh, I. (Technion, Hafia (Israel))

1994-04-15T23:59:59.000Z

427

Low dimensional magnetism  

E-Print Network (OSTI)

Magnetism in Ultracold Gases 4 Magnetic phase diagram of aMagnetism . . . . . . . . . . . .1.3 Magnetism in condensedIntroduction 1 Brief introduction to magnetism 1.1 Classic

Kjall, Jonas Alexander

2012-01-01T23:59:59.000Z

428

Methods of classical mechanics applied to turbulence stresses in a tip leakage vortex  

SciTech Connect

Moore et al. measured the six Reynolds stresses in a tip leakage vortex in a linear turbine cascade. Stress tensor analysis, as used in classical mechanics, has been applied to the measured turbulence stress tensors. Principal directions and principal normal stresses are found. A solid surface model, or three-dimensional glyph, for the Reynolds stress tensor is proposed and used to view the stresses throughout the tip leakage vortex. Modeled Reynolds stresses using the Boussinesq approximation are obtained from the measured mean velocity strain rate tensor. The comparison of the principal directions and the three-dimensional graphic representations of the strain and Reynolds stress tensors aids in the understanding of the turbulence and what is required to model it.

Moore, J.G.; Schorn, S.A.; Moore, J. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)

1996-10-01T23:59:59.000Z

429

A model for vortex-induced vibration analysis of long-span bridges  

Science Journals Connector (OSTI)

Abstract Long-span structures are susceptible to wind-induced vibrations due to their low oscillation frequency and low mechanical damping. Although many efforts have been made in the past to model vortex-induced vibration of circular cylinders, limited studies can be found for non-circular cross sections representative of long-span bridge decks. A model for vortex-induced vibration analysis of long-span bridge is presented in this paper. The aeroelastic equation of motion of the model, a procedure to extract aeroelastic coefficients from wind tunnel experiments, analysis of full-scale structures incorporating loss of spanwise correlation of aeroelastic forces, and comparison between simulated and full-scale measured responses on a twin deck bridge (Fred Hartman bridge, Baytown, Texas) are discussed. Six bluff sections – Deer Isle bridge, Tsurumi bridge, Fred Hartman bridge, generic rectangular, H shaped, and circular models – were considered in this research program.

Mehedy Mashnad; Nicholas P. Jones

2014-01-01T23:59:59.000Z

430

Magnetic Viscosity  

Science Journals Connector (OSTI)

1 January 1893 research-article Magnetic Viscosity J. Hopkinson E. Wilson F. Lydall The Royal Society is collaborating with JSTOR to digitize, preserve, and extend access to Proceedings of the Royal Society of London. www.jstor.org

1893-01-01T23:59:59.000Z

431

Rock magnetism  

Science Journals Connector (OSTI)

The past three decades have witnessed a new paradigm, the plate tectonics paradigm, in Earth sciences. The record of the Earth's magnetic field stored in rocks played a major role in the establishment of this par...

Ronald T. Merrill

1989-01-01T23:59:59.000Z

432

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

433

Reduced gravity Rankine cycle system design and optimization study with passive vortex phase separation  

E-Print Network (OSTI)

REDUCED GRAVITY RANKINE CYCLE SYSTEM DESIGN AND OPTIMIZATION STUDY WITH PASSIVE VORTEX PHASE SEPARATION A Thesis by KEVIN ROBERT SUPAK Submitted to the Office of Graduate Studies of Texas A&M University... SEPARATION A Thesis by KEVIN ROBERT SUPAK Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee, Frederick...

Supak, Kevin Robert

2008-10-10T23:59:59.000Z

434

Effects of syngas composition on combustion induced vortex breakdown (CIVB) flashback in a swirl stabilized combustor  

Science Journals Connector (OSTI)

Flame flashback attributed to combustion induced vortex breakdown (CIVB) is a major design challenge for swirl stabilized burner combustors. This paper presents an experimental investigation of combustion induced vortex breakdown (CIVB) flashback propensity for flames yielded from Hydrogen (H2)–Carbon Monoxide (CO) fuel blends and actual synthesized gas (syngas) mixtures. A two-fold experimental approach, consisting of a high definition digital imaging system and a high speed PIV system, was employed. The main emphasis was on the effect of concentration of different constituents in fuel mixtures on flashback limit. In addition, the effect of Swirl Number on flashback propensity was discussed. The percentage of H2 in fuel mixtures played the dominant role when CIVB flashback occurred. For a given air mass flow rate, the mixture containing a higher percentage of H2 underwent flashback at much leaner conditions. Flashback maps for actual syngas fuel compositions showed a distinct behavior when various concentrations of diluents were introduced in the mixture. For the two major diluents tested, carbon dioxide (CO2) and nitrogen dioxide (NO2), CO2 was more dominant. The effect of Swirl Number on the flashback propensity was also tested and showed a decrease with an increase in Swirl Number. The final portion of this paper also provides an analysis of flow field of reacting flames which revealed complex vortex–chemistry interactions leading to vortex breakdown and flashback. Based on the experimental results a parametric model similar to Peclet Number approach was developed employing a flame quenching concept. A value of the quench parameter, Cquench was obtained from the correlation of flow Peclet Number and flame Peclet Number, which was observed to be dominated by the fuel composition rather than Swirl Number.

Bidhan Dam; Gilberto Corona; Mir Hayder; Ahsan Choudhuri

2011-01-01T23:59:59.000Z

435

Aircraft Emissions Deposited in the Stratosphere and Within the Arctic Polar Vortex. Final report  

SciTech Connect

This report describes an analysis of the quantity of emissions (water vapor, NO(x)) projected to be deposited directly within the Arctic polar vortex by projected fleets of Mach 2.4 high speed civil transports (HSCT`s). It also evaluates the amount of emissions from subsonic aircraft which are emitted into the lower stratosphere using aircraft emission inventories developed earlier for May 1990 as representative of the annual average.

Baughcum, S.L.

1996-04-01T23:59:59.000Z

436

Three-Dimensional Nonlinear Lattices: From Oblique Vortices and Octupoles to Discrete Diamonds and Vortex Cubes  

Science Journals Connector (OSTI)

We construct a variety of novel localized topological structures in the 3D discrete nonlinear Schrödinger equation. The states can be created in Bose-Einstein condensates trapped in strong optical lattices and crystals built of microresonators. These new structures, most of which have no counterparts in lower dimensions, range from multipole patterns and diagonal vortices to vortex “cubes” (stack of two quasiplanar vortices) and “diamonds” (formed by two orthogonal vortices).

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

2005-05-23T23:59:59.000Z

437

Tumor Metabolism and Perfusion in Head and Neck Squamous Cell Carcinoma: Pretreatment Multimodality Imaging With {sup 1}H Magnetic Resonance Spectroscopy, Dynamic Contrast-Enhanced MRI, and [{sup 18}F]FDG-PET  

SciTech Connect

Purpose: To correlate proton magnetic resonance spectroscopy ({sup 1}H-MRS), dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), and {sup 18}F-labeled fluorodeoxyglucose positron emission tomography ([{sup 18}F]FDG PET) of nodal metastases in patients with head and neck squamous cell carcinoma (HNSCC) for assessment of tumor biology. Additionally, pretreatment multimodality imaging was evaluated for its efficacy in predicting short-term response to treatment. Methods and Materials: Metastatic neck nodes were imaged with {sup 1}H-MRS, DCE-MRI, and [{sup 18}F]FDG PET in 16 patients with newly diagnosed HNSCC, before treatment. Short-term patient radiological response was evaluated at 3 to 4 months. Correlations among {sup 1}H-MRS (choline concentration relative to water [Cho/W]), DCE-MRI (volume transfer constant [K{sup trans}]; volume fraction of the extravascular extracellular space [v{sub e}]; and redistribution rate constant [k{sub ep}]), and [{sup 18}F]FDG PET (standard uptake value [SUV] and total lesion glycolysis [TLG]) were calculated using nonparametric Spearman rank correlation. To predict short-term responses, logistic regression analysis was performed. Results: A significant positive correlation was found between Cho/W and TLG ({rho} = 0.599; p = 0.031). Cho/W correlated negatively with heterogeneity measures of standard deviation std(v{sub e}) ({rho} = -0.691; p = 0.004) and std(k{sub ep}) ({rho} = -0.704; p = 0.003). Maximum SUV (SUVmax) values correlated strongly with MRI tumor volume ({rho} = 0.643; p = 0.007). Logistic regression indicated that std(K{sup trans}) and SUVmean were significant predictors of short-term response (p < 0.07). Conclusion: Pretreatment multimodality imaging using {sup 1}H-MRS, DCE-MRI, and [{sup 18}F]FDG PET is feasible in HNSCC patients with nodal metastases. Additionally, combined DCE-MRI and [{sup 18}F]FDG PET parameters were predictive of short-term response to treatment.

Jansen, Jacobus F.A. [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Department of Radiology, Maastricht University Medical Center, Maastricht (Netherlands); Schoeder, Heiko [Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Lee, Nancy Y. [Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Stambuk, Hilda E. [Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Wang Ya [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Fury, Matthew G. [Department of Medical Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Patel, Senehal G. [Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Pfister, David G. [Department of Medical Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Shah, Jatin P. [Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Koutcher, Jason A. [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Department of Medical Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Shukla-Dave, Amita, E-mail: davea@mskcc.org [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York (United States); Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, New York (United States)

2012-01-01T23:59:59.000Z

438

Controlling Magnetism at the Nanoscale  

E-Print Network (OSTI)

Manipulation of Magnetism - External148 Conclusion A The Magnetism Cheat Sheet A.1 Magnetic157 A.2 Magnetism Unit Conversion

Wong, Jared

2012-01-01T23:59:59.000Z

439

Energy cost associated with vortex crossing in superconductors  

Science Journals Connector (OSTI)

Starting from the Ginzburg-Landau free energy of a type-II superconductor in a magnetic field we estimate the energy associated with two vortices crossing. The calculations are performed by assuming that we are in a part of the phase diagram where the lowest-Landau-level approximation is valid. We consider only two vortices but with two markedly different sets of boundary conditions: on a sphere and on a plane with quasiperiodic boundary conditions. We find that the answers are very similar suggesting that the energy is localized to the crossing point. The crossing energy is found to be field and temperature dependent with a value at the experimentally measured melting line of U×?7.5kTm?1.16/cL2, where cL is the Lindemann-melting-criterion parameter. The crossing energy is then used with an extension of the Marchetti, Nelson, and Cates hydrodynamic theory to suggest an explanation of the recent transport experiments of Safar et al.

M. A. Moore and N. K. Wilkin

1994-10-01T23:59:59.000Z

440

Phonon spectrum of QCD vacuum in magnetic-field-induced superconducting phase  

E-Print Network (OSTI)

In the background of a sufficiently strong magnetic field the vacuum was suggested to become an ideal electric conductor (highly anisotropic superconductor) due to an interplay between the strong and electromagnetic forces. The superconducting ground state resembles an Abrikosov lattice state in an ordinary type-II superconductor: it is an inhomogeneous structure made of a (charged vector) quark-antiquark condensate pierced by vortices. In this paper the acoustic (phonon) vibrational modes of the vortex lattice are studied in the mean-field approach at zero temperature. Using an effective model based on a vector meson dominance, we show that in the infrared limit the longitudinal (transverse) acoustic vibrations of the vortex lattice possess a linear (quadratic) dispersion relation corresponding to type I (type II) Nambu-Goldstone modes.

Chernodub, M N; Verschelde, Henri

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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

Phonon spectrum of QCD vacuum in magnetic-field-induced superconducting phase  

E-Print Network (OSTI)

In the background of a sufficiently strong magnetic field the vacuum was suggested to become an ideal electric conductor (highly anisotropic superconductor) due to an interplay between the strong and electromagnetic forces. The superconducting ground state resembles an Abrikosov lattice state in an ordinary type--II superconductor: it is an inhomogeneous structure made of a (charged vector) quark-antiquark condensate pierced by vortices. In this paper the acoustic (phonon) vibrational modes of the vortex lattice are studied at zero temperature. Using an effective model based on a vector meson dominance, we show that in the infrared limit the longitudinal (transverse) acoustic vibrations of the vortex lattice possess a linear (quadratic) dispersion relation corresponding to type I (type II) Nambu--Goldstone modes.

M. N. Chernodub; Jos Van Doorsselaere; Henri Verschelde

2014-01-01T23:59:59.000Z

442

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

443

Aerodynamic performance and characteristic of vortex structures for Darrieus wind turbine. II. The relationship between vortex structure and aerodynamic performance  

Science Journals Connector (OSTI)

In this paper transient computational fluid dynamics (CFD) simulations of a straight-bladed Darrieus type vertical axis wind turbine were performed by means of an in-house CFD code. The Spalart-Allmaras turbulence model was implemented in the numerical code for the turbulence. Particular emphasis was placed on effect of interaction between vortices and blades on the aerodynamic performance of the simulated turbine at different tip speed and solidity ratios. The obtained results suggested that vortices were shed from previous blade passages and the close encounter of a rotor blade with these vortices can have a considerable impact on power coefficient of the simulated turbine during operation at different tip speed ratios. As a result possible reasons for the changes in the behavior of this type of turbine due to the variation of tip speed ratio and solidity were proposed.

2014-01-01T23:59:59.000Z

444

Petroglyphs, Lighting, and Magnetism  

E-Print Network (OSTI)

1950 Electricity and Magnetism: Theory and Applications.I Petroglyphs, Lightning, and Magnetism | Walker Figure 8.I Petroglyphs, Lightning, and Magnetism | Walker Figure IL

Walker, Merle F

2007-01-01T23:59:59.000Z

445

E-Print Network 3.0 - asymptotically large magnetic Sample Search...  

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

asymptotically large magnetic Page: << < 1 2 3 4 5 > >> 1 Dynamics of chaotic magnetic lines and noble ITB's in the Tokamap J. H. Misguich and Fusion BFR Working Group (*)...

446

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

447

Dynamics of a confined dusty fluid in a sheared ion flow  

SciTech Connect

Dynamics of an isothermally driven dust fluid is analyzed which is confined in an azimuthally symmetric cylindrical setup by an effective potential and is in equilibrium with an unconfined sheared flow of a streaming plasma. Cases are analyzed where the confining potential constitutes a barrier for the driven fluid, limiting its spatial extension and boundary velocity. The boundary effects entering the formulation are characterized by applying the appropriate boundary conditions and a range of solutions exhibiting single and multiple vortex are obtained. The equilibrium solutions considered in the cylindrical setup feature a transition from single to multiple vortex state of the driven flow. Effects of (i) the variation in dust viscosity, (ii) coupling between the driving and the driven fluid, and (iii) a friction determining the equilibrium dynamics of the driven system are characterized.

Laishram, Modhuchandra; Sharma, Devendra; Kaw, Predhiman K. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

2014-07-15T23:59:59.000Z

448

Magnetic Catalysis vs Magnetic Inhibition  

E-Print Network (OSTI)

We discuss the fate of chiral symmetry in an extremely strong magnetic field B. We investigate not only quark fluctuations but also neutral meson effects. The former would enhance the chiral-symmetry breaking at finite B according to the Magnetic Catalysis, while the latter would suppress the chiral condensate once B exceeds the scale of the hadron structure. Using a chiral model we demonstrate how neutral mesons are subject to the dimensional reduction and the low dimensionality favors the chiral-symmetric phase. We point out that this effect, the Magnetic Inhibition, can be a feasible explanation for recent lattice-QCD data indicating the decreasing behavior of the chiral-restoration temperature with increasing B.

Kenji Fukushima; Yoshimasa Hidaka

2012-09-06T23:59:59.000Z

449

Magnetic Stereoscopy  

E-Print Network (OSTI)

The space mission STEREO will provide images from two viewpoints. An important aim of the STEREO mission is to get a 3D view of the solar corona. We develop a program for the stereoscopic reconstruction of 3D coronal loops from images taken with the two STEREO spacecraft. A pure geometric triangulation of coronal features leads to ambiguities because the dilute plasma emissions complicates the association of features in image 1 with features in image 2. As a consequence of these problems the stereoscopic reconstruction is not unique and multiple solutions occur. We demonstrate how these ambiguities can be resolved with the help of different coronal magnetic field models (potential, linear and non-linear force-free fields). The idea is that, due to the high conductivity in the coronal plasma, the emitting plasma outlines the magnetic field lines. Consequently the 3D coronal magnetic field provides a proxy for the stereoscopy which allows to eliminate inconsistent configurations. The combination of stereoscopy and magnetic modelling is more powerful than one of these tools alone. We test our method with the help of a model active region and plan to apply it to the solar case as soon as STEREO data become available.

Thomas Wiegelmann; Bernd Inhester

2006-12-21T23:59:59.000Z

450

Turbine blade platform film cooling with simulated stator-rotor purge flow with varied seal width and upstream wake with vortex  

E-Print Network (OSTI)

phase locations to model the unsteady wake formed at the trailing edge of the upstream vane. Delta wings were also placed in four positions to create a vortex similar to the passage vortex at the exit of the vane. The film cooling effectiveness...

Blake, Sarah Anne

2009-05-15T23:59:59.000Z

451

Model system for slow dynamics  

Science Journals Connector (OSTI)

Systems whose dynamics are described by a quasilogarithmic or stretched-exponential time dependence are usually fitted by models which use disorder to create a distribution of relaxation times. Here we describe a model which decays slowly towards equilibrium but does not require disorder to provide the slow dynamics. The model consists of a spin system with the spins interacting via the dipole-dipole interaction. The model is able to replicate the more pronounced features observed in the magnetization decay of magnetic systems and high-temperature superconductors.

D. K. Lottis; R. M. White; E. Dan Dahlberg

1991-07-15T23:59:59.000Z

452

Reconnection in orthogonally interacting vortex tubes: Direct numerical simulations and quantifications  

Science Journals Connector (OSTI)

The three?dimensional time evolution of two orthogonally offset cylindrical vortices of equal strength is simulated by solving the hyperviscosity?regularized incompressible Navier–Stokes equations. A Fourier pseudospectral method with a time?split integration scheme is used for the solution. Four runs with different Reynolds numbers ranging between 690–2100 are performed each with a resolution of 963 collocation points. The sequence of important physical processes and the evolution of local and global quantities such as vorticity velocity and mean?square strain rate are presented. It is found that the growth rate of the maximum vorticity is at most exponential. The Reynolds number dependence of the time scale of reconnection the vorticity growth rate and the time at which the maximum vorticity is attained are examined and differences between the present results and Saffman’s essentially two?dimensional model predictions are encountered and elucidated. The distributions of the eigenvalues ? ? ? and the corresponding eigenvectors s ? s ? s ? of the rate of strain tensor S i j are calculated at different times. It is found that as the mean?square strain rate ? increases during the evolution s ? and the vorticity vector ? are perfectly aligned and ?>0 in high ? regions. Strong temporal spatial and Reynolds number dependence of the strain fields is also seen. Evidence is presented that during reconnection the vorticity growth in newly forming bridges takes place in the vicinity of the upper stagnation line segment of the vortex dipole due to the nature of the vortex stretching term. Also examined is the initial finger formation and it is found that the initial nonuniform axial stretching and the displacement of the vortex cores due to a lift force play an important role in this process.

O. N. Boratav; R. B. Pelz; N. J. Zabusky

1992-01-01T23:59:59.000Z

453

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

2004-06-15T23:59:59.000Z

454

Vortex states in a binary mixture of Bose-Einstein condensates  

Science Journals Connector (OSTI)

The vortex configurations in the Bose-Einstein condensate of a mixture of two different spin states |F=1,mf=-1? and |2,1? of 87Rb atoms corresponding to the recent experiments by Matthews et al. [Phys. Rev. Lett. 83, 2498 (1999)] are considered in the framework of the Thomas-Fermi approximation as functions of N2/N1, where N1 is the number of atoms in the state |1,-1? and N2 in the state |2,1?. Ranges of this ratio are determined within which the various configurations of the binary condensate are stable.

S. T. Chui; V. N. Ryzhov; E. E. Tareyeva

2001-01-11T23:59:59.000Z

455

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

456

Femtosecond laser fabrication of micro and nano-disks in single layer graphene using vortex Bessel beams  

SciTech Connect

We report the fabrication of micro and nano-disks in single layer chemical vapor deposition graphene on glass substrate using femtosecond laser ablation with vortex Bessel beams. The fabricated graphene disks with diameters ranging from 650?nm to 4??m were characterized by spatially resolved micro-Raman spectroscopy. The variation of ablation threshold was investigated as a function of the number of pulses showing an incubation effect. A very high degree of size control of the fabricated graphene disks is enabled using a sequence of femtosecond pulses with different vortex orders.

Wetzel, Benjamin, E-mail: benjamin.wetzel@femto-st.fr; Xie, Chen; Lacourt, Pierre-Ambroise; Dudley, John M.; Courvoisier, Francois [Département d'Optique P.M. Duffieux, Institut FEMTO-ST, UMR–6174 CNRS, Université de Franche-Comté, 25030 Besançon (France)] [Département d'Optique P.M. Duffieux, Institut FEMTO-ST, UMR–6174 CNRS, Université de Franche-Comté, 25030 Besançon (France)

2013-12-09T23:59:59.000Z

457

Review: Magnetic fields of O stars  

E-Print Network (OSTI)

Since 2002, strong, organized magnetic fields have been firmly detected at the surfaces of about 10 Galactic O-type stars. In this paper I will review the characteristics of the inferred fields of individual stars, as well as the overall population. I will discuss the extension of the 'magnetic desert', first inferred among the A-type stars, to O stars up to 60 solar masses. I will discuss the interaction of the winds of the magnetic stars with the fields above their surfaces, generating complex 'dynamical magnetosphere' structures detected in optical and UV lines, and in X-ray lines and continuum. Finally, I will discuss the detection of a small number of variable O stars in the LMC and SMC that exhibit spectral characteristics analogous to the known Galactic magnetic stars, and that almost certainly represent the first known examples of extra-Galactic magnetic stars.

Wade, G A

2014-01-01T23:59:59.000Z

458

Magnetic Reconnection in Astrophysical and  

E-Print Network (OSTI)

Magnetic Reconnection in Astrophysical and Laboratory Plasmas Ellen G. Zweibel1 and Masaaki Yamada2 astrophysics, magnetic fields, magnetic reconnection Abstract Magnetic reconnection is a topological rearrangement of magnetic field that converts magnetic energy to plasma energy. Astrophysical flares, from

459

Electronic Structure and Magnetism in Diluted Magnetic Semiconductors  

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

Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Electronic Structure and Magnetism in Diluted Magnetic Semiconductors Print Wednesday, 29 November 2006 00:00...

460

National High Magnetic Field Laboratory Audio Dictionary: Magnetic...  

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

Links Magnets from Mini to Mighty Meet the Magnets How to Make an Electromagnet (audio slideshow) Compasses in Magnetic Fields (interactive tutorial) Magnetic Field Around a...

Note: This page contains sample records for the topic "dynamic magnetic vortex" 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.


461

THREE-DIMENSIONAL SIMULATIONS OF MAGNETOHYDRODYNAMIC WAVES IN MAGNETIZED SOLAR ATMOSPHERE  

SciTech Connect

We present results of three-dimensional numerical simulations of magnetohydrodynamic (MHD) wave propagation in a solar magnetic flux tube. Our study aims at understanding the properties of a range of MHD wave modes generated by different photospheric motions. We consider two scenarios observed in the lower solar photosphere, namely, granular buffeting and vortex-like motion, among the simplest mechanism for the generation of waves within a strong, localized magnetic flux concentration. We show that granular buffeting is likely to generate stronger slow and fast magnetoacoustic waves as compared to swirly motions. Correspondingly, the energy flux transported differs as a result of the driving motions. We also demonstrate that the waves generated by granular buffeting are likely to manifest in stronger emission in the chromospheric network. We argue that different mechanisms of wave generation are active during the evolution of a magnetic element in the intergranular lane, resulting in temporally varying emission at chromospheric heights.

Vigeesh, G. [Department of Astronomy, New Mexico State University, Las Cruces, NM (United States); Fedun, V.; Erdelyi, R. [SP2RC, Department of Applied Mathematics, University of Sheffield (United Kingdom); Hasan, S. S. [Indian Institute of Astrophysics, Bangalore (India)

2012-08-10T23:59:59.000Z

462

Investigation of Peptide Folding by Nuclear Magnetic Resonance Spectroscopy  

E-Print Network (OSTI)

. Solution-state nuclear magnetic resonance (NMR) is a powerful technique to investigate protein structure, dynamics, and folding mechanisms, since it provides residue-specific information. One of the major contributions that govern protein structure appears...

Hwang, SoYoun

2012-07-16T23:59:59.000Z

463

National High Magnetic Field Laboratory - Scientist Profiles...  

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

"Spatially resolved electronic structure inside and outside the vortex cores of a high-temperature superconductor", Nature 413, 501-504 (2001). 30. V. F. Mitrovi, E. E....

464

Effect of magnetic field on the photon detection in thin superconducting meander structures  

Science Journals Connector (OSTI)

We have studied the influence of an externally applied magnetic field on the photon and dark count rates of meander-type niobium nitride superconducting nanowire single-photon detectors. Measurements have been performed at a temperature of 4.2 K, and magnetic fields up to 250 mT have been applied perpendicularly to the meander plane. While photon count rates are field independent at weak applied fields, they show a strong dependence at fields starting from approximately ±25 mT. This behavior, as well as the magnetic field dependence of the dark count rates, is in good agreement with the recent theoretical model of vortex-assisted photon detection and spontaneous vortex crossing in narrow superconducting lines. However, the local reduction of the superconducting free energy due to photon absorption, which is the fitting parameter in the model, increases much slower with the photon energy than the model predicts. Furthermore, changes in the free-energy during photon counts and dark counts depend differently on the current that flows through the meander. This indicates that photon counts and dark counts occur in different parts of the meander.

R. Lusche; A. Semenov; Y. Korneeva; A. Trifonov; A. Korneev; G. Gol'tsman; H.-W. Hübers

2014-03-19T23:59:59.000Z

465

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

466

Quantum Dissociation of a Vortex-Antivortex Pair in a Long Josephson Junction M.V. Fistul,1  

E-Print Network (OSTI)

Quantum Dissociation of a Vortex-Antivortex Pair in a Long Josephson Junction M.V. Fistul,1 A VAV pair manifests itself in a switching of the Josephson junction from the superconducting biased single Josephson junctions (JJs), various SQUIDs, and small Josephson junction arrays, contain

Wallraff, Andreas

467

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 obtained from a chemical reaction-diffusion system in which wave propagation is limited to a finite band of wavelengths and in which no solitary pulses exist. Wave patterns increase their size through repeated

Steinbock, Oliver

468

Energy Losses Due to Vortex Shedding from the Lower Edge of a Vertical Plate Attacked by Surface Waves  

Science Journals Connector (OSTI)

...Vertical Plate Attacked by Surface Waves M. Stiassnie E. Naheer Irina Boguslavsky...The ratio between the flux of the energy taken out by the vortex generation process , and the incoming wave energy flux , is shown to be given by where...

1984-01-01T23:59:59.000Z

469

Modeling bubbles and droplets in magnetic fluids Mark S. Korlie, Arup Mukherjee, Bogdan G. Nita, John G.  

E-Print Network (OSTI)

and linear magnetic material are assumed and uniform imposed magnetic fields are considered, although of vertical fields, due to a combination of elongation along the field lines and the fluid dynamics. In both cases, #12;Modeling bubbles and droplets in magnetic fluids 2 an imposed magnetic field, even

Yecko, Philip

470

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

471

Magnetic fish-robot based on multi-motion control of a flexible magnetic actuator  

Science Journals Connector (OSTI)

This paper presents a biologically inspired fish-robot driven by a single flexible magnetic actuator with a rotating magnetic field in a three-axis Helmholtz coil. Generally, magnetic fish-robots are powered by alternating and gradient magnetic fields, which provide a single motion such as bending the fish-robot's fins. On the other hand, a flexible magnetic actuator driven by an external rotating magnetic field can create several gaits such as the bending vibration, the twisting vibration, and their combination. Most magnetic fish-like micro-robots do not have pectoral fins on the side and are simply propelled by the tail fin. The proposed robot can swim and perform a variety of maneuvers with the addition of pectoral fins and control of the magnetic torque direction. In this paper, we find that the robot's dynamic actuation correlates with the magnetic actuator and the rotating magnetic field. The proposed robot is also equipped with new features, such as a total of six degrees of freedom, a new control method that stabilizes posture, three-dimensional swimming, a new velocity control, and new turning abilities.

Sung Hoon Kim; Kyoosik Shin; Shuichiro Hashi; Kazushi Ishiyama

2012-01-01T23:59:59.000Z

472

Forces on a magnet moving past figure-eight coils  

SciTech Connect

For the first time, the lift, drag, and guidance forces acting on a permanent magnet are measured as the magnet passes over different arrays of figure-eight (null-flux) coils. The experimental results are in good agreement with the predictions of dynamic circuit theory, which is used to explain more optimal coil arrays.

Mulcahy, T.H.; He, Jianliang; Rote, D.M. [Argonne National Lab., IL (United States); Rossing, T.D. [Northern Illinois Univ., De Kalb, IL (United States). Dept. of Physics

1993-03-01T23:59:59.000Z

473

Forces on a magnet moving past figure-eight coils  

SciTech Connect

For the first time, the lift, drag, and guidance forces acting on a permanent magnet are measured as the magnet passes over different arrays of figure-eight (null-flux) coils. The experimental results are in good agreement with the predictions of dynamic circuit theory, which is used to explain more optimal coil arrays.

Mulcahy, T.H.; He, Jianliang; Rote, D.M. (Argonne National Lab., IL (United States)); Rossing, T.D. (Northern Illinois Univ., De Kalb, IL (United States). Dept. of Physics)

1993-01-01T23:59:59.000Z

474

Plasma detachment and momentum transfer in magnetic nozzles  

E-Print Network (OSTI)

Electric Propulsion and Plasma Dynamics Laboratory, Princeton University, Princeton, NJ, 08544 The naturePlasma detachment and momentum transfer in magnetic nozzles Justin M. Little and Edgar Y. Choueiri the interaction of the magnetic field induced by the currents in the plasma with the current in the applied field

Choueiri, Edgar

475

Science Drivers and Technical Challenges for Advanced Magnetic Resonance  

SciTech Connect

This report recaps the "Science Drivers and Technical Challenges for Advanced Magnetic Resonance" workshop, held in late 2011. This exploratory workshop's goal was to discuss and address challenges for the next generation of magnetic resonance experimentation. During the workshop, participants from throughout the world outlined the science drivers and instrumentation demands for high-field dynamic nuclear polarization (DNP) and associated magnetic resonance techniques, discussed barriers to their advancement, and deliberated the path forward for significant and impactful advances in the field.

Mueller, Karl T.; Pruski, Marek; Washton, Nancy M.; Lipton, Andrew S.

2013-03-07T23:59:59.000Z

476

Z2 index for gapless fermionic modes in the vortex core of three-dimensional paired Dirac fermions  

Science Journals Connector (OSTI)

We consider the gapless modes along the vortex line of the fully gapped, momentum independent paired states of three-dimensional Dirac fermions. For this, we require the solution of fermion zero modes of the corresponding two-dimensional problem in the presence of a point vortex, in the plane perpendicular to the vortex line. Based on the spectral symmetry requirement for the existence of the zero mode, we identify the appropriate generalized Jackiw-Rossi Hamiltonians for different paired states. A four-dimensional generalized Jackiw-Rossi Hamiltonian possesses spectral symmetry with respect to an antiunitary operator, and gives rise to a single zero mode only for the odd vorticity, which is formally described by a Z2 index. In the presence of generic perturbations such as chemical potential, Dirac mass, and Zeeman couplings, the associated two-dimensional problem for the odd parity topological superconducting state maps onto two copies of generalized Jackiw-Rossi Hamiltonian, and consequently an odd vortex binds two Majorana fermions. In contrast, there are no zero-energy states for the topologically trivial s-wave superconductor in the presence of any chiral symmetry breaking perturbation in the particle-hole channel, such as regular Dirac mass. We show that the number of one-dimensional dispersive modes along the vortex line is also determined by the index of the associated two-dimensional problem. For an axial superfluid state in the presence of various perturbations, we discuss the consequences of the Z2 index on the anomaly equations.

Bitan Roy and Pallab Goswami

2014-04-14T23:59:59.000Z

477

An experimental investigation of the rolling moment on a flat plate in the presence of a free vortex of known strength  

E-Print Network (OSTI)

not affect their vertical or lateral positioning. The vortex probe assembly is shown in Figure 2. A comparison of the free-stream velocities obtained from the vortex probe assembly and a standard pitot-static tube revealed a difference of less than one...AN EXPERIMENTAL 1NVES1'IGATION OF THE ROLLING MOMENT ON A ILAT PLATE IN THE ?RESENCE OP A FREE VORTEX OF KNOWN STRENGTH A Thesis by MAURICE VERNE VAN DUSEN, JR. Submitted to the Graduate College of Teras A&M University in partial fulfillment...

Van Dusen, Maurice Verne

2012-06-07T23:59:59.000Z

478

Learning About Magnets!  

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

by 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...

479

Interface Magnetism in Multiferroics  

E-Print Network (OSTI)

1.2.1 Magnetism . . . . . . . . . . . . . . . . . . . 1.2.2domain walls . . . . . 3 Magnetism of domain walls in BiFeOof electrical control of magnetism in mixed phase BiFeO 3

He, Qing

2011-01-01T23:59:59.000Z

480

The Magnetic Field in the Solar Atmosphere  

E-Print Network (OSTI)

This publication provides an overview of magnetic fields in the solar atmosphere with the focus lying on the corona. The solar magnetic field couples the solar interior with the visible surface of the Sun and with its atmosphere. It is also responsible for all solar activity in its numerous manifestations. Thus, dynamic phenomena such as coronal mass ejections and flares are magnetically driven. In addition, the field also plays a crucial role in heating the solar chromosphere and corona as well as in accelerating the solar wind. Our main emphasis is the magnetic field in the upper solar atmosphere so that photospheric and chromospheric magnetic structures are mainly discussed where relevant for higher solar layers. Also, the discussion of the solar atmosphere and activity is limited to those topics of direct relevance to the magnetic field. After giving a brief overview about the solar magnetic field in general and its global structure, we discuss in more detail the magnetic field in active regions, the quie...

Wiegelmann, Thomas; Solanki, Sami K

2014-01-01T23:59:59.000Z