Sample records for magnetic vortex state

  1. X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    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...

  2. Electron vortex beams in a magnetic field and spin filter

    E-Print Network [OSTI]

    Debashree Chowdhury; Banasri Basu; Pratul Bandyopadhyay

    2015-02-25T23:59:59.000Z

    We investigate the propagation of electron vortex beams in a magnetic field. It is pointed out that when electron vortex beams carrying orbital angular momentum propagate in a magnetic field, the Berry curvature associated with the scalar electron moving in a cyclic path around the vortex line is modified from that in free space. This alters the spin-orbit interaction, which affects the propagation of nonparaxial beams. The electron vortex beams with tilted vortex lead to spin Hall effect in free space. In presence of a magnetic field in time space we have spin filtering such that either positive or negative spin states emerge in spin Hall currents with clustering of spin $\\frac{1}{2}$ states.

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

    E-Print Network [OSTI]

    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

    We compare magnetic reversal of nanostructured circular magnetic dots of different sizes. This comparison is based on superconducting quantum interference device (SQUID) magnetometry, neutron scattering, Monte Carlo simulation, and analytical...

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

    E-Print Network [OSTI]

    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

    We compare magnetic reversal of nanostructured circular magnetic dots of different sizes. This comparison is based on superconducting quantum interference device (SQUID) magnetometry, neutron scattering, Monte Carlo simulation, and analytical...

  5. Zero-energy states bound to a magnetic pi-flux vortex in a two-dimensional topological insulator

    E-Print Network [OSTI]

    Andrej Mesaros; Robert-Jan Slager; Jan Zaanen; Vladimir Juricic

    2012-10-22T23:59:59.000Z

    We show that the existence of a pair of zero-energy modes bound to a vortex carrying a pi-flux is a generic feature of the topologically non-trivial phase of the M-B model, which was introduced to describe the topological band insulator in HgTe quantum wells. We explicitly find the form of the zero-energy states of the corresponding Dirac equation, which contains a novel momentum-dependent mass term and describes a generic topological transition in a band insulator. The obtained modes are exponentially localized in the vortex-core, with the dependence of characteristic length on the parameters of the model matching the dependence extracted from a lattice version of the model. We consider in full generality the short-distance regularization of the vector potential of the vortex, and show that a particular choice yields the modes localized and simultaneously regular at the origin. Finally, we also discuss a realization of two-dimensional spin-charge separation through the vortex zero-modes.

  6. The universal criterion for switching a magnetic vortex core in soft magnetic nanodots

    SciTech Connect (OSTI)

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

    2008-10-01T23:59:59.000Z

    The universal criterion for ultrafast vortex core switching between core-up and -down vortex bi-states in soft magnetic nanodots was empirically investigated by micromagnetic simulations and combined with an analytical approach. Vortex-core switching occurs whenever the velocity of vortex core motion reaches a critical value, which is {nu}{sub c} = 330 {+-} 37 m/s for Permalloy, as estimated from numerical simulations. This critical velocity was found to be {nu}{sub c} = {eta}{sub c}{gamma} {radical}A{sub ex} with A{sub ex} the exchange stiffness, {gamma} the gyromagnetic ratio, and an estimated proportional constant {eta}{sub c} = 1.66 {+-} 0.18. This criterion does neither depend on driving force parameters nor on the dimension or geometry of the magnetic specimen. The phase diagrams for the vortex core switching criterion and its switching time with respect to both the strength and angular frequency of circular rotating magnetic fields were derived, which offer practical guidance for implementing vortex core switching into future solid state information storage devices.

  7. Direct Imaging of Antiferromagnetic Vortex States

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    H.W. Zhao, J. Bokor, and Z.Q. Qiu, "Direct observation of imprinted antiferromagnetic vortex states in CoOFeAg(001) discs," Nat. Phys. 7, 303 (2011). ALS Science Highlight 235...

  8. Direct Imaging of Antiferromagnetic Vortex States

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and Z.Q. Qiu, "Direct observation of imprinted antiferromagnetic vortex states in CoOFeAg(001) discs," Nat. Phys. 7, 303 (2011). ALS Science Highlight 235 ALSNews Vol. 324...

  9. Ferroelectric nanostructure having switchable multi-stable vortex states

    DOE Patents [OSTI]

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

    2009-09-22T23:59:59.000Z

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

  10. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  11. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  12. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  13. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  14. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn12electron 9November 6, InaprilU .Magnetic Vortex

  15. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)Integrated Codes |IsLove Your Home and It'll Love YouTokamak| NationalMagnetic Vortex

  16. Instability of Non-vortex State toward a Quantized Vortex in Bose-Einstein Condensate under External Rotation

    E-Print Network [OSTI]

    Tomoya Isoshima; Kazushige Machida

    1999-02-27T23:59:59.000Z

    The instability condition of the non-vortex state toward vortex formation is exa mined within the Bogoliubov theory when a Bose-Einstein condensate is under exte rnally forced rotation. The obtained critical angular velocity combined with the previous stability cond itions for a votex yields a detailed phase diagram in the critical velocity vs t he system parameter. This facilitates vortex formation experiments for alkali atom gases confined in a harmonic potential.

  17. Dissipative dynamics of a vortex state in a trapped Bose-condensed gas

    E-Print Network [OSTI]

    P. O. Fedichev; G. V. Shlyapnikov

    1999-06-15T23:59:59.000Z

    We discuss dissipative dynamics of a vortex state in a trapped Bose-condensed gas at finite temperature and draw a scenario of decay of this state in a static trap. The interaction of the vortex with the thermal cloud transfers energy from the vortex to the cloud and induces the motion of the vortex core to the border of the condensate. Once the vortex reaches the border, it immediately decays through the creation of excitations. We calculate the characteristic life-time of a vortex state and address the question of how the dissipative dynamics of vortices can be studied experimentally.

  18. Determination of magnetic vortex chirality using lateral spin-valve and Y. Otani

    E-Print Network [OSTI]

    Otani, Yoshichika

    Determination of magnetic vortex chirality using lateral spin-valve geometry T. Kimuraa and Y October 2005 We demonstrate the determination of the vortex chirality using a nonlocal spin-valve measurement technique in a lateral spin valve consisting of a Permalloy Py disk 1 m in diameter and a Py wire

  19. Interaction between magnetic vortex cores in a pair of nonidentical nanodisks

    SciTech Connect (OSTI)

    Sinnecker, J. P.; Vigo-Cotrina, H.; Garcia, F.; Novais, E. R. P.; Guimarães, A. P., E-mail: apguima@cbpf.br [Centro Brasileiro de Pesquisas Físicas, 22290-180, Rio de Janeiro, Rio de Janeiro (Brazil)

    2014-05-28T23:59:59.000Z

    The coupling of two nonidentical magnetic nanodisks, i.e., with different vortex gyrotropic frequencies, is studied. From the analytical approach, the interactions between the nanodisks along x and y directions (the coupling integrals) were obtained as a function of distance. From the numerical solution of Thiele's equation, we derived the eigenfrequencies of the vortex cores as a function of distance. The motion of the two vortex cores and, consequently, the time dependence of the total magnetization M(t) were derived both using Thiele's equation and by micromagnetic simulation. From M(t), a recently developed method, the magnetic vortex echoes, analogous to the Nuclear Magnetic Resonance spin echoes, was used to compute the distance dependence of the magnetic coupling strength. The results of the two approaches differ by approximately 10%; using one single term, a dependence with distance found is broadly in agreement with studies employing other techniques.

  20. Magnetic response of holographic Lifshitz superconductors:Vortex and Droplet solutions

    E-Print Network [OSTI]

    Arindam Lala

    2014-07-04T23:59:59.000Z

    In this paper a holographic model of $s$-wave superconductor with anisotropic Lifshitz scaling has been considered. In the presence of an external magnetic field our holographic model exhibits both vortex and droplet solutions. Based on analytic methods we have shown that the anisotropy has no effect on the vortex and droplet solutions whereas it may affect the condensation. Our vortex solution closely resembles the Ginzburg-Landau theory and a relation between the upper critical magnetic field and superconducting coherence length has been speculated from this comparison. Using Sturm-Liouville method, the effect of anisotropy on the critical parameters in insulator/superconductor phase transitions has been analyzed.

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

    DOE Patents [OSTI]

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

    2010-04-13T23:59:59.000Z

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

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

    E-Print Network [OSTI]

    Kim, Sangbum

    2006-04-12T23:59:59.000Z

    In part I, a numerical study of the mixed states in a mesoscopic type-II superconducting cylinder is described. Steady-state configurations and transient behavior of the magnetic vortices for various values of the applied magnetic field H...

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

    E-Print Network [OSTI]

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

    2004-01-01T23:59:59.000Z

    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...

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

    E-Print Network [OSTI]

    Kim, Sangbum

    2006-04-12T23:59:59.000Z

    In part I, a numerical study of the mixed states in a mesoscopic type-II superconducting cylinder is described. Steady-state configurations and transient behavior of the magnetic vortices for various values of the applied ...

  5. First-Order Transition in the Magnetic Vortex Matter in Superconducting MgB2 Tuned by Disorder

    E-Print Network [OSTI]

    Boyer, Edmond

    First-Order Transition in the Magnetic Vortex Matter in Superconducting MgB2 Tuned by Disorder T such as Wigner crystals, charge density waves, magnetic bubble arrays, or vortices in type-II superconductors posi- tional correlations. Vortices in superconductors rapidly became the system of choice

  6. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

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  7. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of Science (SC)Integrated Codes |IsLove Your Home and It'll Love YouTokamak| NationalMagnetic

  8. Magnetic Edge States in Graphene

    E-Print Network [OSTI]

    Gabriela Murguia

    2010-08-29T23:59:59.000Z

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

  9. Entanglement spectrum: Identification of the transition from vortex-liquid to vortex-lattice state in a weakly interacting rotating Bose-Einstein condensate

    SciTech Connect (OSTI)

    Liu Zhao; Guo Hongli; Fan Heng [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Vedral, Vlatko [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 (Singapore); Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore)

    2011-01-15T23:59:59.000Z

    We use entanglement to investigate the transition from vortex-liquid phase to vortex-lattice phase in a weakly interacting rotating Bose-Einstein condensate. For the torus geometry, the ground-state entanglement spectrum is analyzed to distinguish these two phases. The low-lying part of the ground-state entanglement spectrum, as well as the behavior of its lowest level, changes clearly when the transition occurs. For the sphere geometry, the entanglement gap in the conformal limit is also studied. We also show that the decrease in entanglement between particles can be regarded as a signal of the transition.

  10. Direct observation of superconducting vortex clusters pinned by a periodic array of magnetic dots in ferromagnetic/superconducting hybrid structures

    E-Print Network [OSTI]

    Metlushko, Vitali

    Direct observation of superconducting vortex clusters pinned by a periodic array of magnetic dots in ferromagnetic/superconducting hybrid structures T. Shapoval,1,* V. Metlushko,2 M. Wolf,1 B. Holzapfel,1 V. Neu,1, Illinois 60612, USA Received 13 November 2009; published 11 March 2010 Strong pinning of superconducting

  11. Vortex state in a doped Mott insulator M. Franz and Z. Tesanovic

    E-Print Network [OSTI]

    Tesanovic, Zlatko

    predicts two types of singly quantized vortices: an insulating ``holon'' vortex in the underdoped and a metallic ``spinon'' vortex in the overdoped region of the phase diagram. We argue that the holon vortex

  12. Bifurcation to vortex solutions in superconducting lms

    E-Print Network [OSTI]

    Chapman, Jon

    Bifurcation to vortex solutions in superconducting #12;lms T. Boeck #3; S.J. Chapman y Mathematical state to a superconducting state in a decreasing magnetic #12;eld is studied for a slab geometry of these behaviours will occur in practice. 1 Introduction If a superconducting body is placed in a suÃ?ciently strong

  13. The Holographic Superconductor Vortex

    E-Print Network [OSTI]

    Marc Montull; Alex Pomarol; Pedro J. Silva

    2009-09-02T23:59:59.000Z

    A gravity dual of a superconductor at finite temperature has been recently proposed. We present the vortex configuration of this model and study its properties. In particular, we calculate the free energy as a function of an external magnetic field, the magnetization and the superconducting density. We also find the two critical magnetic fields that define the region in which the vortex configurations are energetically favorable.

  14. A finite element method with mesh adaptivity for computing vortex states in fast-rotating Bose-Einstein condensates

    E-Print Network [OSTI]

    Boyer, Edmond

    -Einstein condensates Ionut Danaila,a,b , Fr´ed´eric Hechta,b aUPMC Univ Paris 06, UMR 7598, Laboratoire Jacques Abstract Numerical computations of stationary states of fast-rotating Bose-Einstein condensates require-Einstein condensate, vortex, Sobolev gradient, descent method. 1. Introduction Recent research efforts in the field

  15. A finite element method with mesh adaptivity for computing vortex states in fastrotating BoseEinstein condensates

    E-Print Network [OSTI]

    Recanati, Catherine

    ­Einstein condensates Ionut Danaila #,a,b , Frâ??edâ??eric Hecht a,b a UPMC Univ Paris 06, UMR 7598, Laboratoire Jacques Abstract Numerical computations of stationary states of fast­rotating Bose­Einstein condensates require­Einstein condensate, vortex, Sobolev gradient, descent method. 1. Introduction Recent research e#orts in the field

  16. Magnetization reversal assisted by half antivortex states in nanostructured circular cobalt disks

    SciTech Connect (OSTI)

    Lara, A.; Aliev, F. G., E-mail: farkhad.aliev@uam.es [Dpto. Física de la Materia Condensada, Instituto Nicolas Cabrera (INC) and Condensed Matter Physics Institute (IFIMAC), Universidad Autónoma de Madrid, Madrid (Spain); Dobrovolskiy, O. V. [Physikalisches Institut, Goethe University, Frankfurt am Main (Germany); Physics Department, V. Karazin National University, Kharkiv (Ukraine); Prieto, J. L. [Instituto de Sistemas Optoelectrónicos y Microtecnología (ISOM), Universidad Politecnica de Madrid (Spain); Huth, M. [Physikalisches Institut, Goethe University, Frankfurt am Main (Germany)

    2014-11-03T23:59:59.000Z

    The half antivortex, a fundamental topological structure which determines magnetization reversal of submicron magnetic devices with domain walls, has been suggested also to play a crucial role in spin torque induced vortex core reversal in circular disks. Here, we report on magnetization reversal in circular disks with nanoholes through consecutive metastable states with half antivortices. In-plane anisotropic magnetoresistance and broadband susceptibility measurements accompanied by micromagnetic simulations reveal that cobalt (Co) disks with two and three linearly arranged nanoholes directed at 45° and 135° with respect to the external magnetic field show reproducible step-like changes in the anisotropic magnetoresistance and magnetic permeability due to transitions between different intermediate states mediated by vortices and half antivortices confined to the dot nanoholes and edges, respectively. Our findings are relevant for the development of multi-hole based spintronic and magnetic memory devices.

  17. Dynamic control of spin states in interacting magnetic elements

    DOE Patents [OSTI]

    Jain, Shikha; Novosad, Valentyn

    2014-10-07T23:59:59.000Z

    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.

  18. All-optical discrete vortex switch

    SciTech Connect (OSTI)

    Desyatnikov, Anton S. [Nonlinear Physics Center, Research School of Physics and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Dennis, Mark R. [H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Ferrando, Albert [Interdisciplinary Modeling Group, InterTech and Departament d'Optica, Universitat de Valencia, E-46100 Burjassot (Spain)

    2011-06-15T23:59:59.000Z

    We introduce discrete vortex solitons and vortex breathers in circular arrays of nonlinear waveguides. The simplest vortex breather in a four-waveguide coupler is a nonlinear dynamic state changing its topological charge between +1 and -1 periodically during propagation. We find the stability domain for this solution and suggest an all-optical vortex switching scheme.

  19. advanced vortex element: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    method with mesh adaptivity for computing vortex states in fastrotating BoseEinstein condensates Computer Technologies and Information Sciences Websites Summary: ) vortices, vortex...

  20. The Magnetism of Neutron States

    E-Print Network [OSTI]

    B. G. Sidharth

    2003-10-01T23:59:59.000Z

    The recent measurement by Bignami and co-workers of the magnetic field of a neutron star for the first time gives a value that differs by about two orders of magnitude from the expected value. The speculation has been that the nuclear matter in the neutron stars exhibits some exotic behaviour. In this note we argue that this exotic behaviour is an anomalous statistics obeyed by the neutrons, and moreover these considerations lead to a value of the magnetic field that agrees with the observation. The same considerations also correctly give the magnetic fields of the earth and Jupiter.

  1. Explosive magnetic reconnection caused by an X-shaped current-vortex layer in a collisionless plasma

    E-Print Network [OSTI]

    Hirota, Makoto; Morrison, Philip J

    2015-01-01T23:59:59.000Z

    A mechanism for explosive magnetic reconnection is investigated by analyzing the nonlinear evolution of a collisionless tearing mode in a two-fluid model that includes the effects of electron inertia and temperature. These effects cooperatively enable a fast reconnection by forming an X-shaped current-vortex layer centered at the reconnection point. A high-resolution simulation of this model for an unprecedentedly small electron skin depth $d_e$ and ion-sound gyroradius $\\rho_s$, satisfying $d_e=\\rho_s$, shows an explosive tendency for nonlinear growth of the tearing mode, where it is newly found that the explosive widening of the X-shaped layer occurs locally around the reconnection point with the length of the X shape being shorter than the domain length and the wavelength of the linear tearing mode. The reason for the onset of this locally enhanced reconnection is explained theoretically by developing a novel nonlinear and nonequilibrium inner solution that models the local X-shaped layer, and then matchin...

  2. Suppressible pinning of Abrikosov vortices : effects of magnetic vortex arrays on thin superconducting films

    E-Print Network [OSTI]

    Smith, Kevin Daniel

    2008-01-01T23:59:59.000Z

    penetration through the superconductive film as it relatesThus, to sustain superconductivity throughout the materialthe mixed state, type-II superconductors have characteristic

  3. Vortex structures and zero-energy states in the BCS-to-BEC evolution of p-wave resonant Fermi gases

    SciTech Connect (OSTI)

    Mizushima, T.; Machida, K. [Department of Physics, Okayama University, Okayama 700-8530 (Japan)

    2010-05-15T23:59:59.000Z

    Multiply quantized vortices in the BCS-to-BEC (Bose-Einstein condensation) evolution of p-wave resonant Fermi gases are investigated theoretically. The vortex structure and the low-energy quasiparticle states are discussed, based on the self-consistent calculations of the Bogoliubov-de Gennes and gap equations. We reveal the direct relation between the macroscopic structure of vortices, such as particle densities, and the low-lying quasiparticle state. In addition, the net angular momentum for multiply quantized vortices with a vorticity {kappa} is found to be expressed by a simple equation, which reflects the chirality of the Cooper pairing. Hence, the observation of the particle density depletion and the measurement of the angular momentum will provide the information on the core-bound state and p-wave superfluidity. Moreover, the details on the zero energy Majorana state are discussed in the vicinity of the BCS-to-BEC evolution. It is demonstrated numerically that the zero energy Majorana state appears in the weak coupling BCS limit only when the vortex winding number is odd. The {kappa} branches of the core-bound states for a vortex state with vorticity {kappa} exist; however, only one of them can be the zero energy. This zero energy state vanishes at the BCS-BEC topological phase transition because of interference between the core-bound and edge-bound states.

  4. Vortex methods and vortex statistics

    SciTech Connect (OSTI)

    Chorin, A.J.

    1993-05-01T23:59:59.000Z

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

  5. Vortex lattice for a holographic superconductor

    E-Print Network [OSTI]

    Kengo Maeda; Makoto Natsuume; Takashi Okamura

    2009-12-17T23:59:59.000Z

    We investigate the vortex lattice solution in a (2+1)-dimensional holographic model of superconductors constructed from a charged scalar condensate. The solution is obtained perturbatively near the second-order phase transition and is a holographic realization of the Abrikosov lattice. Below a critical value of magnetic field, the solution has a lower free energy than the normal state. Both the free energy density and the superconducting current are expressed by nonlocal functions, but they reduce to the expressions in the Ginzburg-Landau (GL) theory at long wavelength. As a result, a triangular lattice becomes the most favorable solution thermodynamically as in the GL theory of type II superconductors.

  6. Vortex methods

    SciTech Connect (OSTI)

    Chorin, A.J. [California Univ., Berkeley, CA (United States). Dept. of Mathematics]|[Lawrence Berkeley Lab., CA (United States)

    1993-06-01T23:59:59.000Z

    Vortex methods originated from the observation that in incompressible inviscid flow vorticity (or, more accurately, circulation) is a conserved quantity, as can be readily deduced from the absence of tangential stresses. Thus, if the vorticity is known at time t=0, one can find the flow at a later time by simply following the vorticity. In this narrow context, a vortex method is a numerical method that follows vorticity. The author restricts himself in these lectures to a special class of numerical vortex methods, those that are based on a Lagrangian transport of vorticity in hydrodynamics by smoothed particles (blobs) and those whose analysis contributes to the understanding of blob methods. Blob methods started in the 1930`s.

  7. Suppression of Magnetic State Decoherence Using Ultrafast Optical Pulses

    E-Print Network [OSTI]

    C. Search; P. R. Berman

    2000-03-01T23:59:59.000Z

    It is shown that the magnetic state decoherence produced by collisions in a thermal vapor can be suppressed by the application of a train of ultrafast optical pulses.

  8. Reply to "Comment on `Microwave vortex dissipation of superconducting Nd-Ce-Cu-O epitaxial films in high magnetic fields' "

    E-Print Network [OSTI]

    Yeh, Nai-Chang

    in high magnetic fields' " N.-C. Yeh1 and D. M. Strayer2 1Department of Physics, California Institute of Technology, Pasadena, California 91125, USA 2 Jet Propulsion Laboratory, California Institute of Technology of these modes are insensitive to the application of external magnetic fields, be- cause magnetic fields do

  9. Josephson vortex lattice in layered superconductors

    SciTech Connect (OSTI)

    Koshelev, A. E., E-mail: koshelev@anl.gov [Argonne National Laboratory, Materials Science Division (United States); Dodgson, M. J. W. [Cavendish Laboratory, Theory of Condensed Matter Group (United Kingdom)] [Cavendish Laboratory, Theory of Condensed Matter Group (United Kingdom)

    2013-09-15T23:59:59.000Z

    Many superconducting materials are composed of weakly coupled conducting layers. Such a layered structure has a very strong influence on the properties of vortex matter in a magnetic field. This review focuses on the properties of the Josephson vortex lattice generated by the magnetic field applied in the direction of the layers. The theoretical description is based on the Lawrence-Doniach model in the London limit, which takes only the phase degree of freedom of the superconducting order parameter into account. In spite of its simplicity, this model leads to an amazingly rich set of phenomena. We review in detail the structure of an isolated vortex line and various properties of the vortex lattice, in both dilute and dense limits. In particular, we extensively discuss the influence of the layered structure and thermal fluctuations on the selection of lattice configurations at different magnetic fields.

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

    E-Print Network [OSTI]

    Murphy, G C; Drury, L O'C

    2010-01-01T23:59:59.000Z

    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.

  11. Invariants for Tendex and Vortex Fields

    E-Print Network [OSTI]

    Kenneth A. Dennison; Thomas W. Baumgarte

    2012-08-06T23:59:59.000Z

    Tendex and vortex fields, defined by the eigenvectors and eigenvalues of the electric and magnetic parts of the Weyl curvature tensor, form the basis of a recently developed approach to visualizing spacetime curvature. In analogy to electric and magnetic fields, these fields are coordinate-dependent. However, in a further analogy, we can form invariants from the tendex and vortex fields that are invariant under coordinate transformations, just as certain combinations of the electric and magnetic fields are invariant under coordinate transformations. We derive these invariants, and provide a simple, analytical demonstration for non-spherically symmetric slices of a Schwarzschild spacetime.

  12. Magnetic ground state of semiconducting transition metal trichalcogenide monolayers

    SciTech Connect (OSTI)

    Sivadas, Mr. Nikhil [Carnegie Mellon University (CMU); Daniels, Matthew W. [Carnegie Mellon University (CMU); Swendsen, Robert H. [Carnegie Mellon University (CMU); Okamoto, Satoshi [ORNL; Xiao, Di [Carnegie Mellon University (CMU)

    2015-01-01T23:59:59.000Z

    Layered transition-metal trichalcogenides with the chemical formula ABX3 have attracted recent interest as potential candidates for two-dimensional magnets. Using first-principles calculations within density functional theory, we investigate the magnetic ground states of monolayers of Mn- and Cr-based semiconducting trichalcogenides.We show that the second and third nearest-neighbor exchange interactions (J2 and J3) between magnetic ions, which have been largely overlooked in previous theoretical studies, are crucial in determining the magnetic ground state. Specifically, we find that monolayer CrSiTe3 is an antiferromagnet with a zigzag spin texture due to significant contribution from J3, whereas CrGeTe3 is a ferromagnet with a Curie temperature of 106 K. Monolayers of Mn compounds (MnPS3 and MnPSe3) always show antiferromagnetic N eel order. We identify the physical origin of various exchange interactions, and demonstrate that strain can be an effective knob for tuning the magnetic properties. Possible magnetic ordering in the bulk is also discussed. Our study suggests that ABX3 can be a promising platform to explore two-dimensional magnetic phenomena.

  13. Electron spin magnetism of zigzag graphene nanoribbon edge states

    SciTech Connect (OSTI)

    Xu, Kun, E-mail: xu83@purdue.edu; Ye, Peide D. [School of Electrical and Computer Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States)

    2014-04-21T23:59:59.000Z

    The electron spin states of zigzag graphene nanoribbon (ZGNR) edge play a pivotal role in the applications of graphene nanoribbons. However, the exact arrangements of the electron spins remain unclear to date. In this report, the electronic spin states of the ZGNR edge have been elucidated through a combination of quantum chemical investigation and previous electron spin resonance experiment observations. An alternating ? and ? spin configuration of the unpaired electrons along the ZGNR edge is established in ambient condition without any external magnetic field, and the origin of the spin magnetism of the ZGNR edge is revealed. It paves a pathway for the understanding and design of graphene based electronic and spintronic devices.

  14. Understanding and controlling complex states arising from magnetic frustration

    SciTech Connect (OSTI)

    Zapf, Vivien [Los Alamos National Laboratory

    2012-06-01T23:59:59.000Z

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

  15. Phases of Atom-Molecule Vortex Matter

    SciTech Connect (OSTI)

    Woo, S. J.; Bigelow, N. P. [Department of Physics and Astronomy, University of Rochester, Rochester, New York (United States); Park, Q-Han [Department of Physics, Korea University, Seoul (Korea, Republic of)

    2008-03-28T23:59:59.000Z

    We study ground state vortex configurations in a rotating atom-molecule Bose-Einstein condensate. It is found that the coherent coupling between the atomic and molecular condensates can render a pairing of atomic and molecular vortices into a composite structure that resembles a carbon dioxide molecule. Structural phase transitions of vortex lattices are also explored through different physical parameters including the rotational frequency of the system.

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

    E-Print Network [OSTI]

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

    2003-01-01T23:59:59.000Z

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

  17. Localized Axion Photon States in a Strong Magnetic Field

    E-Print Network [OSTI]

    E. I. Guendelman

    2008-01-04T23:59:59.000Z

    We consider the axion field and electromagnetic waves with rapid time dependence, coupled to a strong time independent, asymptotically approaching a constant at infinity "mean" magnetic field, which takes into account the back reaction from the axion field and electromagnetic waves with rapid time dependence in a time averaged way. The direction of the self consistent mean field is orthogonal to the common direction of propagation of the axion and electromagnetic waves with rapid time dependence and parallel to the polarization of these electromagnetic waves. Then, there is an effective U(1) symmetry mixing axions and photons. Using the natural complex variables that this U(1) symmetry suggests we find localized planar soliton solutions. These solutions appear to be stable since they produce a different magnetic flux than the state with only a constant magnetic field, which we take as our "ground state". The solitons also have non trivial U(1) charge defined before, different from the uncharged vacuum.

  18. Creation and pinning of vortex-antivortex pairs

    E-Print Network [OSTI]

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

    2006-01-01T23:59:59.000Z

    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...

  19. Improved vortex reactor system

    DOE Patents [OSTI]

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

    1995-01-01T23:59:59.000Z

    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.

  20. Vortex diode jet

    DOE Patents [OSTI]

    Houck, Edward D. (Idaho Falls, ID)

    1994-01-01T23:59:59.000Z

    A fluid transfer system that combines a vortex diode with a jet ejector to transfer liquid from one tank to a second tank by a gas pressurization method having no moving mechanical parts in the fluid system. The vortex diode is a device that has a high resistance to flow in one direction and a low resistance to flow in the other.

  1. Magnetic Charge of the Stark States of Hydrogen Atoms

    E-Print Network [OSTI]

    T. Pradhan

    2008-09-28T23:59:59.000Z

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

  2. Ground-state magnetic phase diagram of bow-tie graphene nanoflakes in external magnetic field

    SciTech Connect (OSTI)

    Sza?owski, Karol, E-mail: kszalowski@uni.lodz.pl, E-mail: kszalowski@wp.pl [Department of Solid State Physics, Faculty of Physics and Applied Informatics, University of ?ód?, ul. Pomorska 149/153, 90-236 ?ód? (Poland)

    2013-12-28T23:59:59.000Z

    The magnetic phase diagram of a ground state is studied theoretically for graphene nanoflakes of bow-tie shape and various sizes in external in-plane magnetic field. The tight-binding Hamiltonian supplemented with Hubbard term is used to model the electronic structure of the systems in question. The existence of the antiferromagnetic phase with magnetic moments localized at the sides of the bow-tie is found for low field and a field-induced spin-flip transition to ferromagnetic state is predicted to occur in charge-undoped structures. For small nanoflake doped with a single charge carrier, the low-field phase is ferrimagnetic and a metamagnetic transition to ferromagnetic ordering can be forced by the field. The critical field is found to decrease with increasing size of the nanoflake. The influence of diagonal and off-diagonal disorder on the mentioned magnetic properties is studied. The effect of off-diagonal disorder is found to be more important than that of diagonal disorder, leading to significantly widened distribution of critical fields for disordered population of nanoflakes.

  3. Neutron Scattering Studies of Vortex Matter in Type-II Superconductors

    SciTech Connect (OSTI)

    Xinsheng Ling

    2012-02-02T23:59:59.000Z

    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.

  4. Magnetic switching behaviors of orbital states with different magnetic quantum numbers in Au/Fe/MgO multilayer system

    SciTech Connect (OSTI)

    Suzuki, Kosuke, E-mail: kosuzuki@gunma-u.ac.jp; Takubo, Shota; Kato, Tadashi; Yamazoe, Masatoshi; Hoshi, Kazushi; Sakurai, Hiroshi [Department of Electronics and Informatics, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515 (Japan); Homma, Yoshiya [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, 2145-2 Narita-cho, Oarai-machi, Higashiibaraki-gun, Ibaraki 311-1313 (Japan); Itou, Masayoshi; Sakurai, Yoshiharu [Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2014-08-18T23:59:59.000Z

    A spin specific magnetic hysteresis (SSMH) curve and an orbital specific magnetic hysteresis (OSMH) curve are obtained for Fe/Au/Fe/MgO multilayers by magnetic Compton scattering and SQUID magnetometer measurements. The SSMH curve with each contribution of magnetic quantum number |m|?=?0, 1, and 2 states is obtained by decomposition analyses of magnetic Compton profiles. Residual magnetization is observed for the SSMH curve with magnetic quantum number |m|?=?0, 2 and the OSMH curve. Although the SQUID magnetometer measurements do not show perpendicular magnetic anisotropy (PMA) in the present Fe/Au/Fe/MgO multilayer film, the SSMH curve with magnetic quantum number |m|?=?0, 2 and OSMH curve show switching behaviors of PMA.

  5. Improved vortex reactor system

    DOE Patents [OSTI]

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

    1995-05-09T23:59:59.000Z

    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.

  6. Magnetically bound states of electronic and positronic hydrogen ions: The case of zero orbital angular momentum

    E-Print Network [OSTI]

    California at San Diego, University of

    orbital angular momentum J, and zero net spin i.e., it is a singlet state 2 . Furthermore a positronMagnetically bound states of electronic and positronic hydrogen ions: The case of zero orbital in a uniform magnetic field B, concentrating on states with zero orbital angular momentum J. It is shown

  7. Feasibility of a vortex transistor

    SciTech Connect (OSTI)

    Nevirkovets, I.P.; Rudenko, E.M.

    1985-08-01T23:59:59.000Z

    An experimental test is reported of the feasibility of developing a vortex transistor using tunnel junctions made from tin. (AIP)

  8. The effect of sterile states on the magnetic moments of neutrinos

    SciTech Connect (OSTI)

    Balantekin, A. B.; Vassh, N. [Physics Department, University of Wisconsin, Madison WI 53706 (United States)

    2014-06-24T23:59:59.000Z

    We briefly review recent work exploring the effect of light sterile neutrino states on the neutrino magnetic moment as explored by the reactor and solar neutrino experiments.

  9. Magnetically induced splitting of a giant vortex state in a mesoscopic superconducting disk D. S. Golubovi,1

    E-Print Network [OSTI]

    Moshchalkov, Victor V.

    , whose dimensions are comparable to the supercon- ducting coherence length T and the penetration depth.4 and 1 nm, respectively. The triangle is separated from the supercon- ducting disk by a 2-nm Si spacer

  10. Seeing the magnetic monopole through the mirror of topological surface states

    SciTech Connect (OSTI)

    Qi, Xiao-Liang; Li, Rundong; /Stanford U., Phys. Dept.; Zang, Jiadong; /Fudan U.; Zhang, Shou-Cheng; /Stanford U., Phys. Dept. /Fudan U.

    2010-03-25T23:59:59.000Z

    Existence of the magnetic monopole is compatible with the fundamental laws of nature, however, this illusive particle has yet to be detected experimentally. In this work, we show that an electric charge near the topological surface state induces an image magnetic monopole charge due to the topological magneto-electric effect. The magnetic field generated by the image magnetic monopole can be experimentally measured, and the inverse square law of the field dependence can be determined quantitatively. We propose that this effect can be used to experimentally realize a gas of quantum particles carrying fractional statistics, consisting of the bound states of the electric charge and the image magnetic monopole charge.

  11. A dusty plasma device for producing extended, steady state, magnetized, dusty plasma columns

    E-Print Network [OSTI]

    Merlino, Robert L.

    A dusty plasma device for producing extended, steady state, magnetized, dusty plasma columns Wenjun with an existing Q machine, to produce extended, steady state, magnetized plasma columns. The dusty plasma device (DPD) is to be used for the investigation of waves in dusty plasmas and of other plasma/dust aspects

  12. Ground State of Magnetic Dipoles on a Two-Dimensional Lattice: Structural Phases in Complex Plasmas

    SciTech Connect (OSTI)

    Feldmann, J. D.; Kalman, G. J. [Department of Physics, Boston College, 140 Commonwealth Avenue, Chestnut Hill, Massachusetts, 02467 (United States); Hartmann, P. [Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Rosenberg, M. [Department of Electrical and Computer Engineering, University of California-San Diego, La Jolla, California, 92093 (United States)

    2008-02-29T23:59:59.000Z

    We study analytically and by molecular dynamics simulations the ground state configuration of a system of magnetic dipoles fixed on a two-dimensional lattice. We find different phases, in close agreement with previous results. Building on this result and on the minimum energy requirement we determine the equilibrium lattice configuration, the magnetic order (ferromagnetic versus antiferromagnetic), and the magnetic polarization direction of a system of charged mesoscopic particles with magnetic dipole moments, in the domain where the strong electrostatic coupling leads to a crystalline ground state. Orders of magnitudes of the parameters of the system relevant to possible future dusty plasma experiments are discussed.

  13. -STABILITY AND VORTEX MOTION IN TYPE II SUPERCONDUCTORS

    E-Print Network [OSTI]

    Spirn, Daniel

    -STABILITY AND VORTEX MOTION IN TYPE II SUPERCONDUCTORS MATTHIAS KURZKE AND DANIEL SPIRN Abstract. 1. Introduction 1.1. Physical background. The evolution of a superconducting material is usu- ally of the magnetic field and the electric field potential for a superconducting sample R2 . The parameter

  14. Desingularization of periodic vortex sheet roll-up

    SciTech Connect (OSTI)

    Krasny, R.

    1986-08-01T23:59:59.000Z

    The equations governing periodic vortex sheet roll-up from analytic initial data are desingularized. Linear stability analysis shows that this diminishes the vortex sheet model's short wavelength instability, yielding a numerically more tractable set of equations. Computational evidence is presented which indicates that this approximation converges, beyond the critical time of singularity formation in the vortex sheet, if the mesh is refined and the smoothing parameter is reduced in the proper order. The results suggest that the vortex sheet rolls up into a double branched spiral past the critical time. It is demonstrated that either higher machine precision or a spectra filter can be used to maintain computational accuracy as the smoothing parameter is decreased. Some conjectures on the model's long time asymptotic state are given.

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

    E-Print Network [OSTI]

    S. Regnier; E. R. Priest

    2008-05-12T23:59:59.000Z

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

  16. The Butterfly Effect on Magnetic Vortices

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    A. Vogel, J.-I. Hong, G. Meier, and P. Fischer, "Stochastic formation of magnetic vortex structures in asymmetric disks triggered by chaotic dynamics," Nature Communications 5,...

  17. Liquid Vortex Shielding for Fusion Energy Applications

    SciTech Connect (OSTI)

    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

    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.

  18. Vortex-Based Aero- and Hydrodynamic Estimation

    E-Print Network [OSTI]

    Hemati, Maziar Sam

    2013-01-01T23:59:59.000Z

    2001. [Kra91] R. Krasny. “Vortex Sheet Computations: Roll-NK94] M. Nitsche and R. Krasny. “A Numerical Study of Vortex

  19. A fully implicit method for 3D quasi-steady state magnetic advection-diffusion.

    SciTech Connect (OSTI)

    Siefert, Christopher; Robinson, Allen Conrad

    2009-09-01T23:59:59.000Z

    We describe the implementation of a prototype fully implicit method for solving three-dimensional quasi-steady state magnetic advection-diffusion problems. This method allows us to solve the magnetic advection diffusion equations in an Eulerian frame with a fixed, user-prescribed velocity field. We have verified the correctness of method and implementation on two standard verification problems, the Solberg-White magnetic shear problem and the Perry-Jones-White rotating cylinder problem.

  20. Vortex and Droplet Engineering in Holographic Superconductors

    E-Print Network [OSTI]

    Tameem Albash; Clifford V. Johnson

    2009-08-22T23:59:59.000Z

    We give a detailed account of the construction of non--trivial localized solutions in a 2+1 dimensional model of superconductors using a 3+1 dimensional gravitational dual theory of a black hole coupled to a scalar field. The solutions are found in the presence of a background magnetic field. We use numerical and analytic techniques to solve the full Maxwell--scalar equations of motion in the background geometry, finding condensate droplet solutions, and vortex solutions possessing a conserved winding number. These solutions and their properties, which we uncover, help shed light on key features of the (B,T) phase diagram.

  1. Magnetic moments of the ground-state $\\mathbf{J^P=(3/2)}^{+}$ baryon decuplet

    E-Print Network [OSTI]

    Milton Dean Slaughter

    2011-07-18T23:59:59.000Z

    The magnetic moment - a function of the electric charge form factor $F_{1}(q^{2})$ and the magnetic dipole form factor $F_{2}(q^{2})$ at zero four-momentum transfer $q^{2}$-of the ground-state $J^{P}=(3/2)^{+}$ baryon decuplet magnetic moments have been studied for many years with limited success. At present, only the magnetic moment of the $\\Omega^{-}$ has been accurately determined. We calculate nonperturbatively the magnetic moments of the \\emph{physical baryon decuplet $J^{P}=(3/2)^{+}$} members and in particular, we obtain $\\mu_{\\Delta^{++}}= (+3.67 \\pm 0.07) \\mu_{N}$, $\\mu_{\\Delta^{+}}= (+1.83 \\pm 0.04) \\mu_{N}$, $\\mu_{\\Delta^{0}}= (0) \\mu_{N}$, and the magnetic moments of their $U$-Spin partners in terms of $\\Omega^{-}$ magnetic moment data.

  2. Magnetic domain structure and magnetization reversal in submicron-scale Co dots

    SciTech Connect (OSTI)

    Fernandez, A., LLNL

    1998-02-17T23:59:59.000Z

    We present a magnetic force microscopy (MFM) analysis of arrays of submicron-scale Co dots fabricated by interference lithography. The dots are thin (180-300 A) and are elliptical in shape. MFM of these structures reveals that they relax into highly ordered remanent states whose symmetry and configuration are governed by their shape anisotropy. In particular, when the dots are saturated along the easy-axis, a uniformly magnetized state persists at remanence. However, when the dots are saturated in hard-axis, they relax into a single-vortex state in which the circulation can have either sign. Both remanent states are characterized by smoothly varying magnetization patterns and a high degree of uniformity across the array. We attribute the ordered behavior of these structures to the film microstructure, which allows the shape anisotropy to dominate over magnetocrystalline anisotropy. By imaging a series of minor-loop remanent states, we show that magnetization reversal in these structures occurs via the nucleation and annihilation of a single vortex. Magnetic hysteresis loop measurements are consistent with these observations and provide additional details. Furthermore, we present the results of micromagnetic simulations, which are in excellent agreement with both the MFM images and the hysteresis loop measurements.

  3. Implementation of State Transfer Hamiltonians in Spin Chains with Magnetic Resonance Techniques

    E-Print Network [OSTI]

    Cappellaro, Paola

    2014-01-01T23:59:59.000Z

    Nuclear spin systems and magnetic resonance techniques have provided a fertile platform for experimental investigation of quantum state transfer in spin chains. From the first observation of polarization transfer, predating ...

  4. VORTEX BREAKDOWN INCIPIENCE: THEORETICAL CONSIDERATIONS

    E-Print Network [OSTI]

    Erlebacher, Gordon

    ­dimensional boundary layer (Hall 2;3 , Mager 4 ); (ii) vortex breakdown is a consequence of hydrodynamic instabilityVORTEX BREAKDOWN INCIPIENCE: THEORETICAL CONSIDERATIONS S. A. Berger Department of Mechanical in Science and Engineering NASA Langley Research Center Hampton, VA 23681­0001 ABSTRACT The sensitivity

  5. Topological superconductivity, topological confinement, and the vortex quantum Hall effect

    SciTech Connect (OSTI)

    Diamantini, M. Cristina; Trugenberger, Carlo A. [INFN and Dipartimento di Fisica, University of Perugia, via A. Pascoli, I-06100 Perugia (Italy); SwissScientific, chemin Diodati 10, CH-1223 Cologny (Switzerland)

    2011-09-01T23:59:59.000Z

    Topological matter is characterized by the presence of a topological BF term in its long-distance effective action. Topological defects due to the compactness of the U(1) gauge fields induce quantum phase transitions between topological insulators, topological superconductors, and topological confinement. In conventional superconductivity, because of spontaneous symmetry breaking, the photon acquires a mass due to the Anderson-Higgs mechanism. In this paper we derive the corresponding effective actions for the electromagnetic field in topological superconductors and topological confinement phases. In topological superconductors magnetic flux is confined and the photon acquires a topological mass through the BF mechanism: no symmetry breaking is involved, the ground state has topological order, and the transition is induced by quantum fluctuations. In topological confinement, instead, electric charge is linearly confined and the photon becomes a massive antisymmetric tensor via the Stueckelberg mechanism. Oblique confinement phases arise when the string condensate carries both magnetic and electric flux (dyonic strings). Such phases are characterized by a vortex quantum Hall effect potentially relevant for the dissipationless transport of information stored on vortices.

  6. Investigation of Vortex Structures in Gas-Discharge Nonneutral Electron Plasma: II. Vortex Formation, Evolution and Dynamics

    E-Print Network [OSTI]

    Kervalishvili, N A

    2015-01-01T23:59:59.000Z

    The results of experimental investigations of inhomogeneities of gas-discharge nonneutral electron plasma obtained by using the nonperturbing experimental methods [N.A. Kervalishvili, arXiv:1502.02516 [physics.plasm-ph] (2015)] have been presented. Inhomogeneities are the dense solitary vortex structures stretched along the magnetic field, the lifetime of which is much greater than the time of electron-neutral collisions. The processes of formation, evolution and dynamics of vortex structures were studied. The periodic sequence of these processes is described for different geometries of discharge device.

  7. Variable residence time vortex combustor

    DOE Patents [OSTI]

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

    1987-01-01T23:59:59.000Z

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

  8. Quantitative determination of vortex core dimensions in head-to-head domain walls using off-axis electron holography

    E-Print Network [OSTI]

    Dunin-Borkowski, Rafal E.

    transformations.7 Recent experimental reports confirm these predictions of domain wall movement8Quantitative determination of vortex core dimensions in head-to-head domain walls using off-dimensional characterization of vortex core spin structures, which is important for future magnetic data storage based

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

    DOE Patents [OSTI]

    Woolley, Robert D. (Hillsborough, NJ)

    1998-01-01T23:59:59.000Z

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

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

    DOE Patents [OSTI]

    Woolley, R.D.

    1998-09-08T23:59:59.000Z

    A method and apparatus are disclosed for the steady-state measurement of poloidal magnetic field near a tokamak plasma, where the tokamak is configured with respect to a cylindrical coordinate system having z, phi (toroidal), and r axes. The method is based on combining the two magnetic field principles of induction and torque. The apparatus includes a rotor assembly having a pair of inductive magnetic field pickup coils which are concentrically mounted, orthogonally oriented in the r and z directions, and coupled to remotely located electronics which include electronic integrators for determining magnetic field changes. The rotor assembly includes an axle oriented in the toroidal direction, with the axle mounted on pivot support brackets which in turn are mounted on a baseplate. First and second springs are located between the baseplate and the rotor assembly restricting rotation of the rotor assembly about its axle, the second spring providing a constant tensile preload in the first spring. A strain gauge is mounted on the first spring, and electronic means to continually monitor strain gauge resistance variations is provided. Electronic means for providing a known current pulse waveform to be periodically injected into each coil to create a time-varying torque on the rotor assembly in the toroidal direction causes mechanical strain variations proportional to the torque in the mounting means and springs so that strain gauge measurement of the variation provides periodic magnetic field measurements independent of the magnetic field measured by the electronic integrators. 6 figs.

  11. Efficiently computing vortex lattices in fast rotating Bose-Einstein condensates Yanzhi Zhang1,2

    E-Print Network [OSTI]

    Bao, Weizhu

    Efficiently computing vortex lattices in fast rotating Bose-Einstein condensates Yanzhi Zhang1-Einstein condensates (BECs) with strongly repulsive interactions. The key ingredients of the method is to discretize method in time. Different vortex lattice structures of condensate ground state in two-dimensional (2D

  12. Influence of slip on vortex-induced motion of a superhydrophobic cylinder

    E-Print Network [OSTI]

    Rothstein, Jonathan

    Influence of slip on vortex-induced motion of a superhydrophobic cylinder Robert Daniello, Pranesh: Superhydrophobic Ultrahydrophobic Superhydrophobicity Slip Partial slip Drag reduction Vortex Cylinder a b s t r a c t The partial slip boundary condition produced by a superhydrophobic surface in the Cassie state

  13. The quantum equations of state of plasma under the influence of a weak magnetic field

    SciTech Connect (OSTI)

    Hussein, N. A. [Mathematics Department, Faculty of Science, Assiut University, Assiut (Egypt); Eisa, D. A. [Mathematics Department, Faculty of Education, Assiut University, New Valley (Egypt); Eldin, M. G. [Mathematics Department, Faculty of Science, Beni-suef University, Beni Suef (Egypt)

    2012-05-15T23:59:59.000Z

    The aim of this paper is to calculate the magnetic quantum equations of state of plasma, the calculation is based on the magnetic binary Slater sum in the case of low density. We consider only the thermal equilibrium plasma in the case of n{lambda}{sub ab}{sup 3} Much-Less-Than 1, where {lambda}{sub ab}{sup 2}=( Planck-Constant-Over-Two-Pi {sup 2}/m{sub ab}KT) is the thermal De Broglie wave length between two particles. The formulas contain the contributions of the magnetic field effects. Using these results we compute the magnetization and the magnetic susceptibility. Our equation of state is compared with others.

  14. New look at the QCD ground state in a magnetic field

    E-Print Network [OSTI]

    Efrain J. Ferrer; Vivian de la Incera; Israel Portillo; Matthew Quiroz

    2014-06-13T23:59:59.000Z

    We explore chiral symmetry breaking in a magnetic field within a Nambu-Jona-Lasinio model of interacting massless quarks including tensor channels. We show that the new interaction channels open up via Fierz identities due to the explicit breaking of the rotational symmetry by the magnetic field. We demonstrate that the magnetic catalysis of chiral symmetry breaking leads to the generation of two independent condensates, the conventional chiral condensate and a spin-one condensate. While the chiral condensate generates a dynamical fermion mass, the new condensate gives rise to a dynamical anomalous magnetic moment for the fermions. As a consequence, the spectrum of the excitations in all Landau levels, except the lowest one, exhibits Zeeman splitting. Since the pair, formed by a quark and an antiquark with opposite spins, possesses a resultant magnetic moment, an external magnetic field can align it giving rise to a net magnetic moment for the ground state. This is the physical interpretation of the spin-one condensate. Our results show that the magnetically catalyzed ground state in QCD is actually richer than previously thought. The two condensates contribute to the effective mass of the LLL quasiparticles in such a way that the critical temperature for chiral symmetry restoration becomes enhanced.

  15. Solid State Nuclear Magnetic Resonance 29 (2006) 105117 Electron-nuclear cross polarization

    E-Print Network [OSTI]

    Griffin, Robert G.

    2006-01-01T23:59:59.000Z

    Solid State Nuclear Magnetic Resonance 29 (2006) 105­117 Electron-nuclear cross polarization V from an unpaired electron to neighboring nuclei via electron-nuclear cross polarization (e­Hahn cross polarization (CP) process introduced by Pines et al., that is widely used in solid-state nuclear

  16. Effect of steriles states on lepton magnetic moments and neutrinoless double beta decay

    E-Print Network [OSTI]

    Abada, A; Teixeira, A M

    2014-01-01T23:59:59.000Z

    We address the impact of sterile fermion states on the anomalous magnetic moment of charged leptons, as well as their contribution to neutrinoless double beta decays. We illustrate our results in a minimal, effective extension of the Standard Model by one sterile fermion state, and in a well-motivated framework of neutrino mass generation, embedding the Inverse Seesaw into the Standard Model. The simple "3+1" effective case succeeds in alleviating the tension related to the muon anomalous magnetic moment, albeit only at the 3$\\sigma$ level, and for light sterile states (corresponding to a }cosmologically disfavoured regime). Interestingly, our analysis shows that a future $0 \

  17. Entangled three-particle states in magnetic field: Periodic correlations and density matrices

    E-Print Network [OSTI]

    Amitabha Chakrabarti; Anirban Chakraborti

    2010-04-28T23:59:59.000Z

    We present a novel study of the time evolutions of entangled states of three spin-1/2 particles in the presence of a constant external magnetic field, which causes the individual spins to precess and leads to remarkable periodicities in the correlations and density matrices. The emerging patterns of periodicity are studied explicitly for different entangled states and in detail for a particular initial configuration of the velocities. Contributions to precession of anomalous magnetic moments are analysed and general results are also obtained. We then introduce an electric field orthogonal to the magnetic field, linking to the preceding case via a suitable Lorentz transformation, and obtain the corresponding Wigner rotations of the spin states. Finally, we point out for the first time that the entangled states corresponding to well-known ones in the study of 3-particle entanglements, may be classified systematically using a particular coupling of three angular momenta.

  18. Kinetic control of structural and magnetic states in LuBaCo4O7.

    SciTech Connect (OSTI)

    Avci, S.; Chmaissem, O.; Zheng, H.; Huq, A.; Khalyavin, D.; Stephens, P.; Suchomel, M.; Manuel, P.; Mitchell, J. (X-Ray Science Division); (Northern Illinois University); (Oak Ridge National Laboratory); (ISIS, Rutherford Appleton Laboratory); (Stony Brook University)

    2012-01-01T23:59:59.000Z

    The RBaCo{sub 4}O{sub 7} (R = Ca, Y, Tb, Ho, Tm, Yb, Lu) compounds provide a novel topology for studying the competition between triangular geometry and magnetic order. Here, we report the structural and magnetic behavior of the Lu member of this series via neutron and synchrotron x-ray diffraction, magnetization, and resistivity measurements. We determined sequential phase transitions and a strong competition between a stable and a metastable low-temperature state that critically depends on controlled cooling rates and the associated heat removal kinetics. No evidence for long-range ordered magnetism was detected by neutron diffraction at any temperature. However, very slow spin dynamics are evidenced by time-dependent neutron diffraction measurements and can be explained by several competing magnetic phases with incommensurate short-range correlations coexisting in this material.

  19. Towards a beyond 1 GHz solid-state nuclear magnetic resonance: External lock operation in an external current mode for a 500 MHz nuclear magnetic resonance

    SciTech Connect (OSTI)

    Takahashi, Masato; Maeda, Hideaki [RIKEN Systems and Structural Biology Center, Yokohama, Kanagawa 230-0045 (Japan); Graduate School of Yokohama City University, Yokohama, Kanagawa 230-0045 (Japan); Ebisawa, Yusuke; Tennmei, Konosuke [Graduate School of Yokohama City University, Yokohama, Kanagawa 230-0045 (Japan); Yanagisawa, Yoshinori; Nakagome, Hideki [Graduate School of Chiba University, Chiba, Chiba 263-8522 (Japan); Hosono, Masami; Takasugi, Kenji [JEOL RESONANCE Inc., Akishima, Tokyo 196-8558 (Japan); Hase, Takashi; Miyazaki, Takayoshi [Kobe Steel, Ltd., Kobe, Hyogo 651-2271 (Japan); Fujito, Teruaki [Probe Laboratory Inc., Hamura, Tokyo 205-0021 (Japan); Kiyoshi, Tsukasa [Superconducting Wire Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0003 (Japan); Yamazaki, Toshio [RIKEN Systems and Structural Biology Center, Yokohama, Kanagawa 230-0045 (Japan)

    2012-10-15T23:59:59.000Z

    Achieving a higher magnetic field is important for solid-state nuclear magnetic resonance (NMR). But a conventional low temperature superconducting (LTS) magnet cannot exceed 1 GHz (23.5 T) due to the critical magnetic field. Thus, we started a project to replace the Nb{sub 3}Sn innermost coil of an existing 920 MHz NMR (21.6 T) with a Bi-2223 high temperature superconducting (HTS) innermost coil. Unfortunately, the HTS magnet cannot be operated in persistent current mode; an external dc power supply is required to operate the NMR magnet, causing magnetic field fluctuations. These fluctuations can be stabilized by a field-frequency lock system based on an external NMR detection coil. We demonstrate here such a field-frequency lock system in a 500 MHz LTS NMR magnet operated in an external current mode. The system uses a {sup 7}Li sample in a microcoil as external NMR detection system. The required field compensation is calculated from the frequency of the FID as measured with a frequency counter. The system detects the FID signal, determining the FID frequency, and calculates the required compensation coil current to stabilize the sample magnetic field. The magnetic field was stabilized at 0.05 ppm/3 h for magnetic field fluctuations of around 10 ppm. This method is especially effective for a magnet with large magnetic field fluctuations. The magnetic field of the compensation coil is relatively inhomogeneous in these cases and the inhomogeneity of the compensation coil can be taken into account.

  20. Using thermal boundary conditions to engineer the quantum state of a bulk magnet

    E-Print Network [OSTI]

    M. A. Schmidt; D. M. Silevitch; G. Aeppli; T. F. Rosenbaum

    2014-02-13T23:59:59.000Z

    The degree of contact between a system and the external environment can alter dramatically its proclivity to quantum mechanical modes of relaxation. We show that controlling the thermal coupling of cubic centimeter-sized crystals of the Ising magnet $LiHo_xY_{1-x}F_4$ to a heat bath can be used to tune the system between a glassy state dominated by thermal excitations over energy barriers and a state with the hallmarks of a quantum spin liquid. Application of a magnetic field transverse to the Ising axis introduces both random magnetic fields and quantum fluctuations, which can retard and speed the annealing process, respectively, thereby providing a mechanism for continuous tuning between the destination states. The non-linear response of the system explicitly demonstrates quantum interference between internal and external relaxation pathways.

  1. Vortex Liquid Crystals in Anisotropic Type II Superconductors E.W. Carlson,1,2

    E-Print Network [OSTI]

    Carlson, Erica

    Vortex Liquid Crystals in Anisotropic Type II Superconductors E.W. Carlson,1,2 A. H. Castro Neto,1 September 2002; published 25 February 2003) In an isotropic type II superconductor in a moderate magnetic been much interest in high tem- perature superconductors in a magnetic field. Various ex- periments

  2. Modelling of Quench Limit for Steady State Heat Deposits in LHC Magnets

    E-Print Network [OSTI]

    Bocian, D; Siemko, A

    2008-01-01T23:59:59.000Z

    A quench, the transition of a conductor from the superconducting to the normal conducting state, occurs irreversibly in the accelerator magnets if one of the three parameters: temperature, magnetic field or current density exceeds a critical value. Energy deposited in the superconductor by the particle beams provokes quenches detrimental for the accelerator operation. In particular if particles impacting on the vacuum chamber and their secondary showers depose energy in the magnet coils. The Large Hadron Collider (LHC) nominal beam intensity is 3.2 ldr 10^14 protons. A quench occurs if a fraction of the order of 10^7 protons per second is lost locally. A network model is used to simulate the thermodynamic behaviour of the magnets. The heat flow in the network model was validated with measurements performed in the CERN magnet test facility. A steady state heat flow was introduced in the coil by using the quench heaters implemented in the LHC magnets. The value of the heat source current is determined by the ne...

  3. Filamentary structures in dense plasma focus: Current filaments or vortex filaments?

    SciTech Connect (OSTI)

    Soto, Leopoldo, E-mail: lsoto@cchen.cl; Pavez, Cristian; Moreno, José [Comisión Chilena de Energía Nuclear, CCHEN, Casilla 188-D, Santiago (Chile); Center for Research and Applications in Plasma Physics and Pulsed Power, P4, Departamento de Ciencias Físicas, Facultad de Ciencias Exactas, Universidad Andrés Bello, República 220, Santiago (Chile); Castillo, Fermin [Universidad Nacional Autónoma de México, Cuernavaca, México (Mexico); Veloso, Felipe [Instituto de Física, Pontificia Universidad Católica de Chile, 7820436 Santiago (Chile); Auluck, S. K. H. [Bhabha Atomic Research Center, Mumbai 400 085 (India)

    2014-07-15T23:59:59.000Z

    Recent observations of an azimuthally distributed array of sub-millimeter size sources of fusion protons and correlation between extreme ultraviolet (XUV) images of filaments with neutron yield in PF-1000 plasma focus have re-kindled interest in their significance. These filaments have been described variously in literature as current filaments and vortex filaments, with very little experimental evidence in support of either nomenclature. This paper provides, for the first time, experimental observations of filaments on a table-top plasma focus device using three techniques: framing photography of visible self-luminosity from the plasma, schlieren photography, and interferometry. Quantitative evaluation of density profile of filaments from interferometry reveals that their radius closely agrees with the collision-less ion skin depth. This is a signature of relaxed state of a Hall fluid, which has significant mass flow with equipartition between kinetic and magnetic energy, supporting the “vortex filament” description. This interpretation is consistent with empirical evidence of an efficient energy concentration mechanism inferred from nuclear reaction yields.

  4. Gravity waves from vortex dipoles and jets

    E-Print Network [OSTI]

    Wang, Shuguang

    2009-05-15T23:59:59.000Z

    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...

  5. Super-Chandrasekhar White Dwarfs with Magnetic-dependent Equation of State

    E-Print Network [OSTI]

    Zou, Qi-Xiang

    2015-01-01T23:59:59.000Z

    Recently, some over-luminous Ia supernovaes are found, suggesting that their progenitors are white dwarfs more massive than the Chandrasekhar limit, which perhaps result from ultra-strong magnetic field inside the white dwarfs. We present an equation of state, explicitly magnetic-dependent and analytically practicable, and observe that the change of equation of states due to magnetic field waning along radium will so significantly influence the configuration of a white dwarf as that its density does not monotonically decrease, but goes down at first, re-peaks near the crust and falls off again. As a supernovae will, in the single degenerate Ia supernovae system, leave the remnant of its companion and a neutron star (pulsar star), we point out that the observations of these objects can put our model into tests

  6. Solid-State Nuclear Magnetic Resonance Measurements of HIV Fusion Peptide 13

    E-Print Network [OSTI]

    Weliky, David

    Solid-State Nuclear Magnetic Resonance Measurements of HIV Fusion Peptide 13 CO to Lipid 31 P ABSTRACT: Fusion of the human immunodeficiency virus (HIV) membrane and the host cell membrane is an initial step of infection of the host cell. Fusion is catalyzed by gp41, which is an integral membrane

  7. Charge and magnetic states of Mn-, Fe-, and Co-doped monolayer MoS{sub 2}

    SciTech Connect (OSTI)

    Lin, Xianqing [State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China); Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023 (China); Ni, Jun, E-mail: junni@mail.tsinghua.edu.cn [State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China)

    2014-07-28T23:59:59.000Z

    First-principles calculations have been performed to investigate the electronic and magnetic properties of monolayer MoS{sub 2} substitutionally doped with Mn, Fe, and Co in possible charge states (q). We find that the Mn, Fe, and Co dopants substituting for a Mo atom in monolayer MoS{sub 2} (Mn@Mo, Fe@Mo, and Co@Mo) are all magnetic in their neutral and charge states except in the highest positive charge states. Mn@Mo, Fe@Mo, and Co@Mo have the same highest negative charge states of q=?2 for chemical potential of electron just below the conduction band minimum, which corresponds to the electron doping. In the q=?2 state, Mn@Mo has a much larger magnetic moment than its neutral state with the antiferromagnetic coupling between the Mn dopant and its neighboring S atoms maintained, while Fe@Mo and Co@Mo have equal or smaller magnetic moments than their neutral states. The possible charge states of Mn@Mo, Fe@Mo, and Co@Mo and the variation of the magnetic moments for different dopants and charge states are due to the change of the occupation and energy of the anti-bonding defect levels in the band gap. The rich magnetic properties of the neutral and charge states suggest possible realization of the substitutionally Mn-, Fe-, and Co-doped monolayer MoS{sub 2} as dilute magnetic semiconductors.

  8. The London theory of the crossing-vortex lattice in highly anisotropic layered superconductors

    E-Print Network [OSTI]

    S. E. Savel'ev; J. Mirkovic; K. Kadowaki

    2001-05-18T23:59:59.000Z

    A novel description of Josephson vortices (JVs) crossed by the pancake vortices (PVs) is proposed on the basis of the anisotropic London theory. The field distribution of a JV and its energy have been calculated for both dense ($a\\lambda_J$) PV lattices with distance $a$ between PVs, and the nonlinear JV core size $\\lambda_J$. It is shown that the ``shifted'' PV lattice (PVs displaced mainly along JVs in the crossing vortex lattice structure), formed in high out-of-plane magnetic fields transforms into the PV lattice ``trapped'' by the JV sublattice at a certain field, lower than $\\Phi_0/\\gamma^2s^2$, where $\\Phi_0$ is the flux quantum, $\\gamma$ is the anisotropy parameter and $s$ is the distance between CuO$_2$ planes. With further decreasing $B_z$, the free energy of the crossing vortex lattice structure (PV and JV sublattices coexist separately) can exceed the free energy of the tilted lattice (common PV-JV vortex structure) in the case of $\\gamma s<\\lambda_{ab}$ with the in-plane penetration depth $\\lambda_{ab}$ if the low ($B_x<\\gamma\\Phi_0/\\lambda_{ab}^2$) or high ($B_x\\gtrsim \\Phi_0/\\gamma s^2$) in-plane magnetic field is applied. It means that the crossing vortex structure is realized in the intermediate field orientations, while the tilted vortex lattice can exist if the magnetic field is aligned near the $c$-axis and the $ab$-plane as well. In the intermediate in-plane fields $\\gamma\\Phi_0/\\lambda_{ab}^2\\lesssim B_x \\lesssim \\Phi_0/\\gamma s^2$, the crossing vortex structure with the ``trapped'' PV sublattice seems to settle in until the lock-in transition occurs since this structure has the lower energy with respect to the tilted vortex structure in the magnetic field ${\\vec H}$ oriented near the $ab$-plane.

  9. Dynamic magnetization states of a spin valve in the presence of dc and ac currents: Synchronization, modification, and chaos

    E-Print Network [OSTI]

    Li, Charles

    Dynamic magnetization states of a spin valve in the presence of dc and ac currents: Synchronization and numerical calculations of dynamic magnetization states of a spin valve in the presence of dc and ac currents are expected to appear. In this paper, we consider a simple spin valve as a model system to study the problem

  10. Controlled propagation of locally excited vortex dynamics in linear nanomagnet arrays This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Otani, Yoshichika

    Controlled propagation of locally excited vortex dynamics in linear nanomagnet arrays This article. Here, we present a controlled propagation of locally excited magnetic vortex dynamics through a linear. Phys. D: Appl. Phys. 43 (2010) 335001 (7pp) doi:10.1088/0022-3727/43/33/335001 Controlled propagation

  11. Onset of superradiant instabilities in the hydrodynamic vortex model

    E-Print Network [OSTI]

    Shahar Hod

    2014-07-30T23:59:59.000Z

    The hydrodynamic vortex, an effective spacetime geometry for propagating sound waves, is studied analytically. In contrast with the familiar Kerr black-hole spacetime, the hydrodynamic vortex model is described by an effective acoustic geometry which has no horizons. However, this acoustic spacetime possesses an ergoregion, a property which it shares with the rotating Kerr spacetime. It has recently been shown numerically that this physical system is linearly unstable due to the superradiant scattering of sound waves in the ergoregion of the effective spacetime. In the present study we use analytical tools in order to explore the onset of these superradiant instabilities which characterize the effective spacetime geometry. In particular, we derive a simple analytical formula which describes the physical properties of the hydrodynamic vortex system in its critical (marginally-stable) state, the state which marks the boundary between stable and unstable fluid configurations. The analytically derived formula is shown to agree with the recently published numerical data for the hydrodynamic vortex system.

  12. Inhomogeneous Vortex Patterns in Rotating Bose-Einstein Condensates

    E-Print Network [OSTI]

    Correggi, Michele

    2012-01-01T23:59:59.000Z

    We consider a 2D rotating Bose gas described by the Gross-Pitaevskii (GP) theory and investigate the properties of the ground state of the theory for rotational speeds close to the critical speed for vortex nucleation. While one could expect that the vortex distribution should be homogeneous within the condensate we prove by means of an asymptotic analysis in the strongly interacting (Thomas-Fermi) regime that it is not. More precisely we rigorously derive a formula due to Sheehy and Radzihovsky [Phys. Rev. A 70, 063620(R) (2004)] for the vortex distribution, a consequence of which is that the vortex distribution is strongly inhomogeneous close to the critical speed and gradually homogeneizes when the rotation speed is increased. From the mathematical point of view, a novelty of our approach is that we do not use any compactness argument in the proof, but instead provide explicit estimates on the difference between the vorticity measure of the GP ground state and the minimizer of a certain renormalized energy...

  13. Spin counting in electrically detected magnetic resonance via low-field defect state mixing

    SciTech Connect (OSTI)

    Cochrane, Corey J.; Lenahan, Patrick M. [The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2014-03-03T23:59:59.000Z

    The work herein describes a method that allows one to measure paramagnetic defect densities in semiconductor and insulator based devices with electrically detected magnetic resonance (EDMR). The method is based upon the mixing of defect states which results from the dipolar coupling of paramagnetic sites at low magnetic fields. We demonstrate the measurement method with spin dependent tunneling in thin film dielectrics; however, the method should be equally applicable to paramagnetic defect density measurements in semiconductors via the more commonly utilized EDMR technique called spin dependent recombination.

  14. Magnetic nozzle and plasma detachment model for a steady-state flow

    SciTech Connect (OSTI)

    Breizman, B. N.; Tushentsov, M. R.; Arefiev, A. V. [University of Texas at Austin, Austin, Texas 78712 (United States)

    2008-05-15T23:59:59.000Z

    Plasma propulsion concepts that employ a guiding magnetic field raise the question of how the magnetically controlled plasma can detach from the spacecraft. This paper presents a detachment scenario relevant to high-power thrusters in which the plasma can stretch the magnetic field lines to infinity, similar to the solar wind. In previous work, the corresponding ideal magnetohydrodynamics equations have been solved analytically for a plasma flow in a slowly diverging nozzle. That solution indicates that efficient detachment is feasible if the nozzle is sufficiently long. In order to extend the previous model beyond the idealizations of analytical theory, a Lagrangian code is developed in this work to simulate steady-state kinetic plasma flows and to evaluate nozzle efficiency. The code is benchmarked against the analytical results and then used to examine situations that are not analytically tractable, including plasma behavior in the recent Detachment Demonstration Experiment at the National Aeronautics and Space Administration.

  15. Supplementary Figure S1. Schematics of conventional magnetic tweezers and freely-orbiting magnetic tweezers. (a) Schematic of conventional magnetic tweezers. A superparamagnetic bead is

    E-Print Network [OSTI]

    Dekker, Nynke

    . A systematic variation of the (x, y) fluctuation pattern with magnet position resembling a cyclone or vortex in a separate experiment after aligning the magnets in smaller steps about the center and is shown

  16. Exchange and correlation energies of ground states of atoms and molecules in strong magnetic fields

    E-Print Network [OSTI]

    Schmelcher, P; Becken, W

    1999-01-01T23:59:59.000Z

    Using a Hartree-Fock mesh method and a configuration interaction approach based on a generalized Gaussian basis set we investigate the behaviour of the exchange and correlation energies of small atoms and molecules, namely th e helium and lithium atom as well as the hydrogen molecule, in the presence of a magnetic field covering the regime B=0-100a.u. In general the importance of the exchange energy to the binding properties of at oms or molecules increases strongly with increasing field strength. This is due to the spin-flip transitions and in particular due to the contributions of the tightly bound hydrogenic state s which are involved in the corresponding ground states of different symmetries. In contrast to the exchange energy the correlation energy becomes less relevant with increasing field strength. This holds for the individual configurations constituting the ground state and for the crossovers of the global ground state.

  17. Numerical methods for computing the ground state of spin-1 Bose-Einstein condensates in a uniform magnetic field

    E-Print Network [OSTI]

    Bao, Weizhu

    Numerical methods for computing the ground state of spin-1 Bose-Einstein condensates in a uniform for computing the ground-state solution of spin-1 Bose-Einstein condensates subjected to a uniform magnetic to compute the condensate ground state in a harmonic plus optical lattice potential, and the effect

  18. Energy Spectrum of Vortex Tangle

    E-Print Network [OSTI]

    Tsunehiko Araki; Makoto Tsubota; Sergey K. Nemirovskii

    2001-06-29T23:59:59.000Z

    The energy spectrum of superfluid turbulence in the absence of the normal fluid is studied numerically. In order to discuss the statistical properties, we calculated the energy spectra of the 3D velocity field induced by dilute and dense vortex tangles respectively, whose dynamics is calculated by the Biot-Savart law. In the case of a dense tangle, the slope of the energy spectrum is changed at $k=2\\pi/l$, where $l$ is the intervortex spacing. For $k>2\\pi/l$, the energy spectrum has $k^{-1}$ behavior in the same manner as the dilute vortex tangle, while otherwise the slope of the energy spectrum deviates from $k^{-1}$ behavior. We compare the behavior for $k<2\\pi/l$ with the Kolmogorov law.

  19. Divergence of optical vortex beams

    E-Print Network [OSTI]

    Reddy, Salla Gangi; Prabhakar, Shashi; Anwar, Ali; Banerji, J; Singh, R P

    2015-01-01T23:59:59.000Z

    We show, both theoretically and experimentally, that the propagation of optical vortices in free space can be analysed by using the width ($w(z)$) of the host Gaussian beam and the inner and outer radii of the vortex beam at the source plane ($z=0$) as defined in \\textit{Optics Letters \\textbf{39,} 4364-4367 (2014)}. We also studied the divergence of vortex beams, considered as the rate of change of inner or outer radius with the propagation distance, and found that it varies with the order in the same way as that of the inner and outer radii at zero propagation distance. These results may be useful in designing optical fibers for orbital angular momentum modes that play a crucial role in quantum communication.

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

    E-Print Network [OSTI]

    Jaroniec, Christopher P

    2003-01-01T23:59:59.000Z

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

  1. Computing Vortex Sheet Motion Robert Krasny

    E-Print Network [OSTI]

    Krasny, Robert

    Computing Vortex Sheet Motion Robert Krasny Department of Mathematics, University of Michigan, Ann;1574 Robert Krasny with respect to the time variable and obtained results consistent with Moore

  2. Superconducting vortex pinning with artificially prepared nanostructures

    E-Print Network [OSTI]

    Rosen, Yaniv Jacob

    K. Schuller, “Enhanced superconducting vortex pinning withat T/Tc = 0.99 of a superconducting Nb thin film on aof the triangles. The superconducting critical temperature

  3. aircraft vortex spacing: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    calculations and find that nontopological vortex solutions exist as well as Q-ball type solutions, but topological vortex solutions are not admitted. Inyong Cho; Youngone...

  4. 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...

  5. Light propagation around a relativistic vortex flow of dielectric medium

    E-Print Network [OSTI]

    B. Linet

    2000-11-06T23:59:59.000Z

    We determine the path of the light around a dielectric vortex described by the relativistic vortex flow of a perfect fluid.

  6. accelerated vortex ring: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    rings and systems for controlled studies of vortex interactions in Bose-Einstein condensates HEP - Theory (arXiv) Summary: We study controlled methods of preparing vortex...

  7. Direct Imaging of Antiferromagnetic Vortex States

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625govInstrumentstdmadapInactiveVisitingContract Management FermiDavidDiesel pricesDiesel28, 2007,Dirac Dirac

  8. Direct Imaging of Antiferromagnetic Vortex States

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625govInstrumentstdmadapInactiveVisitingContract Management FermiDavidDiesel pricesDiesel28, 2007,Dirac DiracDirect

  9. Direct Imaging of Antiferromagnetic Vortex States

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power AdministrationField Campaign: PotentialFederal Financial Interventions and

  10. Direct Imaging of Antiferromagnetic Vortex States

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power AdministrationField Campaign: PotentialFederal Financial Interventions andDirect Imaging of

  11. Direct Imaging of Antiferromagnetic Vortex States

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power AdministrationField Campaign: PotentialFederal Financial Interventions andDirect Imaging

  12. Direct Imaging of Antiferromagnetic Vortex States

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power AdministrationField Campaign: PotentialFederal Financial Interventions andDirect

  13. Direct Imaging of Antiferromagnetic Vortex States

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power AdministrationField Campaign: PotentialFederal Financial Interventions andDirectDirect

  14. Direct Imaging of Antiferromagnetic Vortex States

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville Power AdministrationField Campaign: PotentialFederal Financial Interventions andDirectDirectDirect

  15. Interaction of mesoscopic magnetic textures with superconductors

    E-Print Network [OSTI]

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

    2002-01-01T23:59:59.000Z

    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...

  16. Vortex dynamics in 4 Banavara N. Shashikanth

    E-Print Network [OSTI]

    Shashikanth, Banavara N.

    Vortex dynamics in 4 Banavara N. Shashikanth Citation: J. Math. Phys. 53, 013103 (2012); doi: 10 OF MATHEMATICAL PHYSICS 53, 013103 (2012) Vortex dynamics in R4 Banavara N. Shashikantha) Mechanical and Aerospace dynamics of Euler's equations for a constant density fluid flow in R4 is studied. Most of the paper focuses

  17. An investigation of the vortex method

    SciTech Connect (OSTI)

    Pryor, D.W. Jr.

    1994-05-01T23:59:59.000Z

    The vortex method is a numerical scheme for solving the vorticity transport equation. Chorin introduced modern vortex methods. The vortex method is a Lagrangian, grid free method which has less intrinsic diffusion than many grid schemes. It is adaptive in the sense that elements are needed only where the vorticity is non-zero. Our description of vortex methods begins with the point vortex method of Rosenhead for two dimensional inviscid flow, and builds upon it to eventually cover the case of three dimensional slightly viscous flow with boundaries. This section gives an introduction to the fundamentals of the vortex method. This is done in order to give a basic impression of the previous work and its line of development, as well as develop some notation and concepts which will be used later. The purpose here is not to give a full review of vortex methods or the contributions made by all the researchers in the field. Please refer to the excellent review papers in Sethian and Gustafson, chapters 1 Sethian, 2 Hald, 3 Sethian, 8 Chorin provide a solid introduction to vortex methods, including convergence theory, application in two dimensions and connection to statistical mechanics and polymers. Much of the information in this review is taken from those chapters, Chorin and Marsden and Batchelor, the chapters are also useful for their extensive bibliographies.

  18. Vortex rings impinging on permeable boundaries

    E-Print Network [OSTI]

    Mujal-Colilles, Anna; Dalziel, Stuart B.; Bateman, Allen

    2015-01-17T23:59:59.000Z

    , and the existence of a rebound of the core parallel to the formation of a secondary 47 vortex with opposite sign [14]. 48 More recently, attention has turned to the possibility of resuspension due to a vortex ring 49 impacting a bed of particles (e.g. [1], [15...

  19. Two regimes of vortex penetration into platelet-shaped type-II superconductors

    SciTech Connect (OSTI)

    Brandt, E. H. [Max-Planck-Institut fuer Metallforschung (Germany)] [Max-Planck-Institut fuer Metallforschung (Germany); Mikitik, G. P., E-mail: mikitik@ilt.kharkov.ua [Ukrainian Academy of Sciences, Verkin Institute for Low Temperature Physics and Engineering (Ukraine); Zeldov, E. [Weizmann Institute of Science, Department of Condensed Matter Physics (Israel)] [Weizmann Institute of Science, Department of Condensed Matter Physics (Israel)

    2013-09-15T23:59:59.000Z

    Vortex penetration into a thin superconducting strip of a rectangular cross section is considered at an increasing applied magnetic field H{sub a}, taking an interplay between the Bean-Livingston and the geometric barriers in the sample into account. We calculate the magnetic field H{sub p} at which the penetration begins and show that two regimes of vortex penetration are possible. In the first regime, vortices appearing at the corners of the strip at H{sub a} = H{sub p} immediately move to its center, where a vortex dome starts to develop. In the second regime, the penetration occurs in two stages. In the first stage, at H{sub a} < H{sub p}, tilted vortices penetrate into the edge regions of the strip, where novel domes are shown to be formed at the top, bottom, and lateral surfaces. In the second stage, at H{sub a} = H{sub p}, the vortex propagation to the center becomes possible. The difference between the regimes manifests itself in slightly different dependences of the magnetic moment of the strip on H{sub a}.

  20. Ergoregion instability: The hydrodynamic vortex

    E-Print Network [OSTI]

    Leandro A. Oliveira; Vitor Cardoso; Luís C. B. Crispino

    2014-05-16T23:59:59.000Z

    Four-dimensional, asymptotically flat spacetimes with an ergoregion but no horizon have been shown to be linearly unstable against a superradiant-triggered mechanism. This result has wide implications in the search for astrophysically viable alternatives to black holes, but also in the understanding of black holes and Hawking evaporation. Here we investigate this instability in detail for a particular setup which can be realized in the laboratory: the {\\it hydrodynamic vortex}, an effective geometry for sound waves, with ergoregion and without an event horizon.

  1. The idea of vortex energy

    E-Print Network [OSTI]

    V. E. Shapiro

    2011-09-22T23:59:59.000Z

    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.

  2. Vortex Energy | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directedAnnualProperty Edit withTianlin BaxinUmweltVillageGraph Home Wzeng'sVortex Energy Jump to:

  3. The Meissner effect in the ground state of free charged Bosons in a constant magnetic field

    E-Print Network [OSTI]

    Walter F. Wreszinski

    2015-01-30T23:59:59.000Z

    The model of free charged Bosons in an external constant magnetic field inside a cylinder, one of the few locally gauge covariant systems amenable to analytic treatment, is rigorously investigated in the semiclassical approximation. The model was first studied by Schafroth and is suitable for the description of quasi-bound electron pairs localized in physical space, so-called Schafroth pairs, which occur in certain compounds. Under the assumption of existence of a solution of the semiclassical problem for which the ground state (g.s.) expectation value of the current $$ is of the London form, i.e., $ = -c |\\phi_{0}(\\vec{x})|^{2} \\vec{A}(\\vec{x})$, where c is a positive constant, $\\vec{A}$ the vector potential and $\\phi_{0}$ the one-particle g.s. wave-function. as well as some regularity assumptions, the magnetic induction may be proved to decay exponentially from its value on the surface of the cylinder. An important role is played by a theorem on the pointwise monotonicity of the ground state wave-function on the potential.

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

    E-Print Network [OSTI]

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

    2014-06-16T23:59:59.000Z

    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.

  5. Vortex pinning by inhomogeneities in type-II superconductors

    E-Print Network [OSTI]

    Chapman, Jon

    Vortex pinning by inhomogeneities in type-II superconductors S.J. Chapman #3;y G. Richardson zx of a curvilinear vortex in an inhomogeneous type-II superconducting material in the limit as the vortex core radius of the superconducting electrons acts as a pinning potential for the vortex, so that vortices will be attracted

  6. Large amplitude spin torque vortex oscillations at zero external field using a perpendicular spin polarizer

    SciTech Connect (OSTI)

    Dussaux, A.; Rache Salles, B.; Jenkins, A. S.; Bortolotti, P.; Grollier, J.; Cros, V.; Fert, A. [Unité Mixte de Physique CNRS/Thales and Université Paris Sud 11, 1 Ave. A. Fresnel, 91767 Palaiseau (France); Grimaldi, E., E-mail: eva.grimaldi@thalesgroup.com [Unité Mixte de Physique CNRS/Thales and Université Paris Sud 11, 1 Ave. A. Fresnel, 91767 Palaiseau (France); CNES, 1 Avenue Edouard Belin, 31400 Toulouse (France); Khvalkovskiy, A. V. [Unité Mixte de Physique CNRS/Thales and Université Paris Sud 11, 1 Ave. A. Fresnel, 91767 Palaiseau (France); A.M. Prokhorov General Physics Institute of RAS, Vavilova Str. 38, 119991 Moscow (Russian Federation); Kubota, H.; Fukushima, A.; Yakushiji, K.; Yuasa, S. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba (Japan)

    2014-07-14T23:59:59.000Z

    We investigate the microwave response of a spin transfer vortex based oscillator in a magnetic tunnel junction with an in-plane reference layer combined with a spin valve with an out-of-plane magnetization spin polarizing layer. The main advantage of this perpendicular spin polarizer is to induce a large spin transfer force even at zero magnetic field, thus leading to a record emitted power (up to 0.6??W) associated to a very narrow spectral linewidth of a few hundreds of kHz. The characteristics of this hybrid vortex based spin transfer nano-oscillator obtained at zero field and room temperature are of great importance for applications based on rf spintronic devices as integrated and tunable microwave source and/or microwave detector.

  7. Spatiotemporal characterization of ultrashort optical vortex pulses

    E-Print Network [OSTI]

    Miranda, Miguel; Rudawski, Piotr; Guo, Chen; Harth, Anne; L'Huillier, Anne; Arnold, Cord L

    2015-01-01T23:59:59.000Z

    Generation of few-cycle optical vortex pulses is challenging due to the large spectral bandwidths, as most vortex generation techniques are designed for monochromatic light. In this work, we use a spiral phase plate to generate few-cycle optical vortices from an ultrafast titanium:sapphire oscillator, and characterize them in the spatiotemporal domain using a recently introduced technique based on spatially resolved Fourier transform spectrometry. The performance of this simple approach to the generation of optical vortices is analyzed from a wavelength dependent perspective, as well as in the spatiotemporal domain, allowing us to completely characterize ultrashort vortex pulses in space, frequency, and time.

  8. Smooth double critical state theory for type-II superconductors

    E-Print Network [OSTI]

    H. S. Ruiz; A. Bad\\'\\ia-Majós

    2010-05-30T23:59:59.000Z

    Several aspects of the general theory for the critical states of a vortex lattice and the magnetic flux dynamics in type-II superconductors are examined by a direct variational optimisation method and widespread physical principles. Our method allows to unify a number of conventional models describing the complex vortex configurations in the critical state regime. Special attention is given to the discussion of the relation between the flux-line cutting mechanism and the depinning threshold limitation. This is done by using a smooth double critical state concept which incorporates the so-called isotropic, elliptical, T and CT models as well-defined limits of our general treatment. Starting from different initial configurations for a superconducting slab in a 3D magnetic field, we show that the predictions of the theory range from the collapse to zero of transverse magnetic moments in the isotropic model, to nearly force free configurations in which paramagnetic values can arbitrarily increase with the applied field for magnetically anisotropic current voltage laws. Noteworthily, the differences between the several model predictions are minimal for the low applied field regime.

  9. Spin Equilibria in Monomeric Manganocenes: Solid State Magnetic and EXAFS Studies

    SciTech Connect (OSTI)

    Walter, M. D.; Sofield, C. D.; Booth, C. H.; Andersen, R. A.

    2009-02-09T23:59:59.000Z

    Magnetic susceptibility measurements and X-ray data confirm that tert-butyl-substituted manganocenes [(Me{sub 3}C){sub n}C{sub 5}H{sub 5?n}]{sub 2}Mn (n = 1, 2) follow the trend previously observed with the methylated manganocenes; that is, electron-donating groups attached to the Cp ring stabilize the low-spin (LS) electronic ground state relative to Cp{sub 2}Mn and exhibit higher spin-crossover (SCO) temperatures. However, introducing three CMe{sub 3} groups on each ring gives a temperature-invariant high-spin (HS) state manganocene. The origin of the high-spin state in [1,2,4-(Me{sub 3}C){sub 3}C{sub 5}H{sub 2}]{sub 2}Mn is due to the significant bulk of the [1,2,4-(Me{sub 3}C){sub 3}C{sub 5}H{sub 2}]{sup -} ligand, which is sufficient to generate severe inter-ring steric strain that prevents the realization of the low-spin state. Interestingly, the spin transition in [1,3-(Me{sub 3}C){sub 2}C{sub 5}H{sub 3}]{sub 2}Mn is accompanied by a phase transition resulting in a significant irreversible hysteresis ({Delta}T{sub c} = 16 K). This structural transition was also observed by extended X-ray absorption fine-structure (EXAFS) measurements. Magnetic susceptibility studies and X-ray diffraction data on SiMe{sub 3}-substituted manganocenes [(Me{sub 3}Si){sub n}C{sub 5}H{sub 5-n}]{sub 2}Mn (n = 1, 2, 3) show high-spin configurations in these cases. Although tetra- and hexasubstituted manganocenes are high-spin at all accessible temperatures, the disubstituted manganocenes exhibit a small low-spin admixture at low temperature. In this respect it behaves similarly to [(Me{sub 3}C)(Me{sub 3}Si)C{sub 5}H{sub 3}]{sub 2}Mn, which has a constant low-spin admixture up to 90 K and then gradually converts to high-spin. Thermal spin-trapping can be observed for [(Me{sub 3}C)(Me{sub 3}Si)C{sub 5}H{sub 3}]{sub 2}Mn on rapid cooling.

  10. The Life of a Vortex Knot

    E-Print Network [OSTI]

    Kleckner, Dustin; Irvine, William T M

    2013-01-01T23:59:59.000Z

    The idea that the knottedness (hydrodynamic Helicity) of a fluid flow is conserved has a long history in fluid mechanics. The quintessential example of a knotted flow is a knotted vortex filament, however, owing to experimental difficulties, it has not been possible until recently to directly generate knotted vortices in real fluids. Using 3D printed hydrofoils and high-speed laser scanning tomography, we generate vortex knots and links and measure their subsequent evolution. In both cases, we find that the vortices deform and stretch until a series of vortex reconnections occurs, eventually resulting several disjoint vortex rings. This article accompanies a fluid dynamics video entered into the Gallery of Fluid Motion at the 66th Annual Meeting of the APS Division of Fluid Dynamics.

  11. The multiple vortex nature of tropical cyclogenesis

    E-Print Network [OSTI]

    Sippel, Jason Allen

    2005-02-17T23:59:59.000Z

    cells and vortices are the respective source of PV production and building blocks for the meso-?-scale vortices. Finally, this thesis discusses issues related to the multiple vortex nature of tropical cyclone formation. For instance, the tracking...

  12. Magnetic state and exchange interaction in GdScGe: Ab initio study X. B. Liu, Z. Altounian, Xianghua Han, Narayan Poudyal, and J. Ping Liu

    E-Print Network [OSTI]

    Liu, J. Ping

    . INTRODUCTION Room temperature magnetic refrigeration, based on magnetocaloric effect (MCE), has attracted muchMagnetic state and exchange interaction in GdScGe: Ab initio study X. B. Liu, Z. Altounian magnetic semiconductor multilayers J. Appl. Phys. 113, 054302 (2013) What does a first-order reversal curve

  13. Reconnection of vortex filaments and Kolmogorov spectrum

    E-Print Network [OSTI]

    Sergey K. Nemirovskii

    2014-04-19T23:59:59.000Z

    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.

  14. Superconducting and magnetic properties of Sr?Ir?Sn??

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Biswas, P. K.; Wang, Kefeng; Amato, A.; Khasanov, R.; Luetkens, H.; Petrovic, C.; Cook, R. M.; Lees, M. R.; Morenzoni, E.

    2014-10-01T23:59:59.000Z

    Magnetization and muon spin relaxation or rotation (µSR) measurements have been performed to study the superconducting and magnetic properties of Sr?Ir?Sn??. From magnetization measurements the lower and upper critical fields of Sr?Ir?Sn?? are found to be 81(1) Oe and 14.4(2) kOe, respectively. Zero-field µSR data show no sign of any magnetic ordering or weak magnetism in Sr?Ir?Sn??. Transverse-field µSR measurements in the vortex state provided the temperature dependence of the magnetic penetration depth ?. The dependence of ??² with temperature is consistent with the existence of single s-wave energy gap in the superconducting state of Sr?Ir?Sn?? with a gap valuemore »of 0.82(2) meV at absolute zero temperature. The magnetic penetration depth at zero temperature ?(0) is 291(3) nm. The ratio ?(0)/kBTc = 2.1(1) indicates that Sr?Ir?Sn?? should be considered as a strong-coupling superconductor.« less

  15. Superconducting and magnetic properties of Sr?Ir?Sn??

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Biswas, P. K. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Wang, Kefeng [Brookhaven National Lab. (BNL), Upton, NY (United States); Amato, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Khasanov, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Luetkens, H. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Petrovic, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Cook, R. M. [Univ. of Warwick, Coventry (United Kingdom); Lees, M. R. [Univ. of Warwick, Coventry (United Kingdom); Morenzoni, E. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    2014-10-01T23:59:59.000Z

    Magnetization and muon spin relaxation or rotation (µSR) measurements have been performed to study the superconducting and magnetic properties of Sr?Ir?Sn??. From magnetization measurements the lower and upper critical fields of Sr?Ir?Sn?? are found to be 81(1) Oe and 14.4(2) kOe, respectively. Zero-field µSR data show no sign of any magnetic ordering or weak magnetism in Sr?Ir?Sn??. Transverse-field µSR measurements in the vortex state provided the temperature dependence of the magnetic penetration depth ?. The dependence of ??² with temperature is consistent with the existence of single s-wave energy gap in the superconducting state of Sr?Ir?Sn?? with a gap value of 0.82(2) meV at absolute zero temperature. The magnetic penetration depth at zero temperature ?(0) is 291(3) nm. The ratio ?(0)/kBTc = 2.1(1) indicates that Sr?Ir?Sn?? should be considered as a strong-coupling superconductor.

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

    SciTech Connect (OSTI)

    Kong, Zueqian

    2010-03-15T23:59:59.000Z

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

  17. Quenched crystal-field disorder and magnetic liquid ground states in Tb?Sn2-xTixO?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gaulin, B. D.; Kermarrec, E.; Dahlberg, M. L.; Matthews, M. J.; Bert, F.; Zhang, J.; Mendels, P.; Fritsch, K.; Granroth, G. E.; Jiramongkolchai, P.; et al

    2015-06-01T23:59:59.000Z

    Solid solutions of the “soft” quantum spin ice pyrochlore magnets Tb?B?O? with B = Ti and Sn display a novel magnetic ground state in the presence of strong B-site disorder, characterized by a low susceptibility and strong spin fluctuations to temperatures below 0.1 K. These materials have been studied using ac susceptibility and ?SR techniques to very low temperatures, and time-of-flight inelastic neutron scattering techniques to 1.5 K. Remarkably, neutron spectroscopy of the Tb³? crystal-field levels appropriate to high B-site mixing (0.5 2-xTixO?) reveal that the doublet ground and first excited states present as continuamore »in energy, while transitions to singlet excited states at higher energies simply interpolate between those of the end members of the solid solution. The resulting ground state suggests an extreme version of a random-anisotropy magnet, with many local moments and anisotropies, depending on the precise local configuration of the six B sites neighboring each magnetic Tb³? ion.« less

  18. Quenched crystal-field disorder and magnetic liquid ground states in Tb?Sn2-xTixO?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gaulin, B. D.; Kermarrec, E.; Dahlberg, M. L.; Matthews, M. J.; Bert, F.; Zhang, J.; Mendels, P.; Fritsch, K.; Granroth, G. E.; Jiramongkolchai, P.; Amato, A.; Baines, C.; Cava, R. J.; Schiffer, P.

    2015-06-01T23:59:59.000Z

    Solid solutions of the “soft” quantum spin ice pyrochlore magnets Tb?B?O? with B = Ti and Sn display a novel magnetic ground state in the presence of strong B-site disorder, characterized by a low susceptibility and strong spin fluctuations to temperatures below 0.1 K. These materials have been studied using ac susceptibility and ?SR techniques to very low temperatures, and time-of-flight inelastic neutron scattering techniques to 1.5 K. Remarkably, neutron spectroscopy of the Tb³? crystal-field levels appropriate to high B-site mixing (0.5 2-xTixO?) reveal that the doublet ground and first excited states present as continua in energy, while transitions to singlet excited states at higher energies simply interpolate between those of the end members of the solid solution. The resulting ground state suggests an extreme version of a random-anisotropy magnet, with many local moments and anisotropies, depending on the precise local configuration of the six B sites neighboring each magnetic Tb³? ion.

  19. Solid-State Nuclear Magnetic Resonance Evidence for an Extended Strand Conformation of the Membrane-Bound HIV-1 Fusion Peptide

    E-Print Network [OSTI]

    Weliky, David

    Solid-State Nuclear Magnetic Resonance Evidence for an Extended Strand Conformation of the Membrane-Bound HIV-1 Fusion Peptide Jun Yang, Charles M. Gabrys, and David P. Weliky* Department of ChemistryVed May 4, 2001 ABSTRACT: Solid-state nuclear magnetic resonance (NMR) spectroscopy was applied

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

    E-Print Network [OSTI]

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

    2015-03-20T23:59:59.000Z

    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 $\\pm\\frac{4\\pi n}{e}\\sin^2\\theta_W$ 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 values of Higgs self-coupling constant $0\\leq \\lambda\\leq 40$ at Weinberg angle $\\theta_W=\\frac{\\pi}{4}$.

  1. On the bifurcation structure of axisyrnmetric vortex breakdown in a constricted pipe

    E-Print Network [OSTI]

    Lopez, John M.

    On the bifurcation structure of axisyrnmetric vortex breakdown in a constricted pipe J. M. Lopez Department of Mathematics and Earth SystemScienceCenter;The PennsylvaniaState University, Universiv Park, Pennsylvania 16802 (Received 5 April 1994; accepted 20 July 1994) The bifurcation structure is presented

  2. Fluid Dynamics Research 33 (2003) 333356 Leapfrogging vortex rings: Hamiltonian structure, geometric

    E-Print Network [OSTI]

    Shashikanth, Banavara N.

    2003-01-01T23:59:59.000Z

    Fluid Dynamics Research 33 (2003) 333­356 Leapfrogging vortex rings: Hamiltonian structure that if the rings are modeled as coaxial circular ÿlaments, their dynamics and Hamil- tonian structure is derivable of Mechanical Engineering, New Mexico State University, Las Cruces, NM 88003, USA b Control and Dynamical

  3. Twisted toroidal vortex-solitons in inhomogeneous media with repulsive nonlinearity

    E-Print Network [OSTI]

    Y. V. Kartashov; B. A. Malomed; Y. Shnir; L. Torner

    2014-12-05T23:59:59.000Z

    Toroidal modes in the form of so-called Hopfions, with two independent winding numbers, a hidden one (twist, s), which characterizes a circular vortex thread embedded into a three-dimensional soliton, and the vorticity around the vertical axis m, appear in many fields, including the field theory, ferromagnetics, and semi- and superconductors. Such topological states are normally generated in multi-component systems, or as trapped quasi-linear modes in toroidal potentials. We uncover that stable solitons with this structure can be created, without any linear potential, in the single-component setting with the strength of repulsive nonlinearity growing fast enough from the center to the periphery, for both steep and smooth modulation profiles. Toroidal modes with s=1 and vorticity m=0,1,2 are produced. They are stable for m1. An approximate analytical solution is obtained for the twisted ring with s=1, m=0. Under the application of an external torque, it rotates like a solid ring. The setting can be implemented in BEC, by means of the Feshbach resonance controlled by inhomogene-ous magnetic fields.

  4. Effects of the microphysical Equation of State in the mergers of magnetized Neutron Stars With Neutrino Cooling

    E-Print Network [OSTI]

    C. Palenzuela; S. L. Liebling; D. Neilsen; L. Lehner; O. L. Caballero; E. O'Connor; M. Anderson

    2015-05-07T23:59:59.000Z

    We study the merger of binary neutron stars using different realistic, microphysical nuclear equations of state, as well as incorporating magnetic field and neutrino cooling effects. In particular, we concentrate on the influence of the equation of state on the gravitational wave signature and also on its role, in combination with cooling and electromagnetic effects, in determining the properties of the hypermassive neutron star resulting from the merger, the production of neutrinos, and the characteristics of ejecta from the system. The ejecta we find are consistent with other recent studies that find soft equations of state produce more ejecta than stiffer equations of state. Moreover, the degree of neutron richness increases for softer equations of state. In light of reported kilonova observations (associated to GRB~130603B and GRB~060614) and the discovery of relatively low abundances of heavy, radioactive elements in deep sea deposits (with respect to possible production via supernovae), we speculate that a soft EoS might be preferred---because of its significant production of sufficiently neutron rich ejecta---if such events are driven by binary neutron star mergers. We also find that realistic magnetic field strengths, obtained with a sub-grid model tuned to capture magnetic amplification via the Kelvin-Helmholtz instability at merger, are generally too weak to affect the gravitational wave signature post-merger within a time scale of $\\approx 10$~ms but can have subtle effects on the post-merger dynamics.

  5. Wave Functions of the Proton Ground State in the Presence of a Uniform Background Magnetic Field in Lattice QCD

    E-Print Network [OSTI]

    Dale S. Roberts; Patrick O. Bowman; Waseem Kamleh; Derek B. Leinweber

    2011-08-08T23:59:59.000Z

    We calculate the probability distributions of quarks in the ground state of the proton, and how they are affected in the presence of a constant background magnetic field. We focus on wave functions in the Landau and Coulomb gauges. We observe the formation of a scalar u-d diquark clustering. The overall distortion of the quark probability distribution under a very large magnetic field, as demanded by the quantisation conditions on the field, is quite small. The effect is to elongate the distributions along the external field axis while localizing the remainder of the distribution.

  6. Vortex Hydro Energy (TRL 5 6 System) - Advanced Integration of...

    Broader source: Energy.gov (indexed) [DOE]

    Vortex Hydro Energy (TRL 5 6 System) - Advanced Integration of Power Take-Off in VIVACE Vortex Hydro Energy (TRL 5 6 System) - Advanced Integration of Power Take-Off in VIVACE...

  7. Critical current density and mechanism of vortex pinning in KxFe2-ySe? doped with S

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lei, Hechang; Petrovic, C.

    2011-08-01T23:59:59.000Z

    We report the critical current density Jc in KxFe2-ySe2-zSz crystals. The Jc can be enhanced significantly with optimal S doping (z=0.99). For K0.70(7)Fe1.55(7)Se1.01(2)S0.99(2), the weak fishtail effect is found for H II c. The normalized vortex pinning forces follow the scaling law with a maximum position at 0.41 of the reduced magnetic field. These results demonstrate that the small size normal point defects dominate the vortex pinning mechanism.

  8. Vortex and gap generation in gauge models of graphene

    E-Print Network [OSTI]

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

    2011-04-22T23:59:59.000Z

    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.

  9. Magnetic susceptibility and equation of state of N_f = 2+1 QCD with physical quark masses

    E-Print Network [OSTI]

    Claudio Bonati; Massimo D'Elia; Marco Mariti; Francesco Negro; Francesco Sanfilippo

    2014-05-13T23:59:59.000Z

    We determine the free energy of strongly interacting matter as a function of an applied constant and uniform magnetic field. We consider N_f = 2+1 QCD with physical quark masses, discretized on a lattice by stout improved staggered fermions and a tree level improved Symanzik pure gauge action, and explore three different lattice spacings. For magnetic fields of the order of those produced in non-central heavy ion collisions (eB ~ 0.1 GeV^2) strongly interacting matter behaves like a medium with a linear response, and is paramagnetic both above and below the deconfinement transition, with a susceptibility which steeply rises in the deconfined phase. We compute the equation of state, showing that the relative increase in the pressure due to the magnetic field gets larger around the transition, and of the order of 10 % for eB ~ 0.1 GeV^2.

  10. Effects of the microphysical Equation of State in the mergers of magnetized Neutron Stars With Neutrino Cooling

    E-Print Network [OSTI]

    Palenzuela, C; Neilsen, D; Lehner, L; Caballero, O L; O'Connor, E; Anderson, M

    2015-01-01T23:59:59.000Z

    We study the merger of binary neutron stars using different realistic, microphysical nuclear equations of state, as well as incorporating magnetic field and neutrino cooling effects. In particular, we concentrate on the influence of the equation of state on the gravitational wave signature and also on its role, in combination with cooling and electromagnetic effects, in determining the properties of the hypermassive neutron star resulting from the merger, the production of neutrinos, and the characteristics of ejecta from the system. The ejecta we find are consistent with other recent studies that find soft equations of state produce more ejecta than stiffer equations of state. Moreover, the degree of neutron richness increases for softer equations of state. In light of reported kilonova observations (associated to GRB~130603B and GRB~060614) and the discovery of relatively low abundances of heavy, radioactive elements in deep sea deposits (with respect to possible production via supernovae), we speculate tha...

  11. Fractal powers in Serrin's swirling vortex solutions

    E-Print Network [OSTI]

    Pavel B?lík; Douglas P. Dokken; Kurt Scholz; Mikhail M. Shvartsman

    2014-04-28T23:59:59.000Z

    We consider a modification of the fluid flow model for a tornado-like swirling vortex developed by J. Serrin, where velocity decreases as the reciprocal of the distance from the vortex axis. Recent studies, based on radar data of selected severe weather events, indicate that the angular momentum in a tornado may not be constant with the radius, and thus suggest a different scaling of the velocity/radial distance dependence. Motivated by this suggestion, we consider Serrin's approach with the assumption that the velocity decreases as the reciprocal of the distance from the vortex axis to the power $b$ with a general $b>0$. This leads to a boundary-value problem for a system of nonlinear differential equations. We analyze this problem for particular cases, both with nonzero and zero viscosity, discuss the question of existence of solutions, and use numerical techniques to describe those solutions that we cannot obtain analytically.

  12. Removing the concavity of the thick center vortex potentials by fluctuating the vortex profile

    E-Print Network [OSTI]

    Sedigheh Deldar; Shahnoosh Rafibakhsh

    2010-03-14T23:59:59.000Z

    The thick center vortex model reproduces important aspects of the potentials between static quark sources as seen in lattice Yang-Mills calculations: Both the intermediate distance behavior, governed by Casimir scaling, as well as the long distance behavior, governed by N-ality, are obtained. However, when a fixed vortex profile is used, these two distance regimes do not connect naturally to each other. The transition in general violates concavity constraints on the potential, especially for higher representations of the gauge group. We demonstrate how this issue can be alleviated when the vortex profile is allowed to fluctuate within this simple model.

  13. Bluff Body Flow Simulation Using a Vortex Element Method

    SciTech Connect (OSTI)

    Anthony Leonard; Phillippe Chatelain; Michael Rebel

    2004-09-30T23:59:59.000Z

    Heavy ground vehicles, especially those involved in long-haul freight transportation, consume a significant part of our nation's energy supply. it is therefore of utmost importance to improve their efficiency, both to reduce emissions and to decrease reliance on imported oil. At highway speeds, more than half of the power consumed by a typical semi truck goes into overcoming aerodynamic drag, a fraction which increases with speed and crosswind. Thanks to better tools and increased awareness, recent years have seen substantial aerodynamic improvements by the truck industry, such as tractor/trailer height matching, radiator area reduction, and swept fairings. However, there remains substantial room for improvement as understanding of turbulent fluid dynamics grows. The group's research effort focused on vortex particle methods, a novel approach for computational fluid dynamics (CFD). Where common CFD methods solve or model the Navier-Stokes equations on a grid which stretches from the truck surface outward, vortex particle methods solve the vorticity equation on a Lagrangian basis of smooth particles and do not require a grid. They worked to advance the state of the art in vortex particle methods, improving their ability to handle the complicated, high Reynolds number flow around heavy vehicles. Specific challenges that they have addressed include finding strategies to accurate capture vorticity generation and resultant forces at the truck wall, handling the aerodynamics of spinning bodies such as tires, application of the method to the GTS model, computation time reduction through improved integration methods, a closest point transform for particle method in complex geometrics, and work on large eddy simulation (LES) turbulence modeling.

  14. Acoustics of finite-aperture vortex beams

    E-Print Network [OSTI]

    Mitri, F G

    2014-01-01T23:59:59.000Z

    A method based on the Rayleigh-Sommerfeld surface integral is provided, which makes it feasible to rigorously model, evaluate and compute the acoustic scattering and other mechanical effects of finite-aperture vortex beams such as the acoustic radiation force and torque on a viscoelastic sphere in various applications in acoustic tweezers and microfluidics, particle entrapment, manipulation and rotation. Partial-wave series expansions are derived for the incident field of acoustic spiraling (vortex) beams, comprising high-order Bessel and Bessel-Gauss beams.

  15. Voltage control of magnetic anisotropy in Fe films with quantum well states

    E-Print Network [OSTI]

    Bauer, Uwe

    The influence of a gate voltage on magnetic anisotropy is investigated in a thin Fe film epitaxially grown on a Ag(1,1,10) substrate and covered by MgO. Oscillations in step-induced magnetic anisotropy due to quantum well ...

  16. Dopant spin states and magnetism of Sn{sub 1?x}Fe{sub x}O{sub 2} nanoparticles

    SciTech Connect (OSTI)

    Punnoose, A., E-mail: apunnoos@boisestate.edu; Dodge, Kelsey; Reddy, K. M.; Franco, Nevil; Chess, Jordan; Eixenberger, Josh [Department of Physics, Boise State University, Boise, Idaho 83725-1570 (United States); Beltrán, J. J. [Department of Physics, Boise State University, Boise, Idaho 83725-1570 (United States); Grupo de Estado Sólido, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No 52-21, Medellín (Colombia); Barrero, C. A. [Grupo de Estado Sólido, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No 52-21, Medellín (Colombia)

    2014-05-07T23:59:59.000Z

    This work reports detailed investigations of a series of ?2.6?nm sized, Sn{sub 1?x}Fe{sub x}O{sub 2} crystallites with x?=?0–0.10 using Mossbauer spectroscopy, x-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance spectroscopy (EPR), and magnetometry to determine the oxidation state of Fe dopants and their role in the observed magnetic properties. The magnetic moment per Fe ion ? was the largest ?6.48?×?10{sup ?3} ?{sub B} for the sample with the lowest (0.001%) Fe doping, and it showed a rapid downward trend with increasing Fe doping. Majority of the Fe ions are in 3+ oxidation state occupying octahedral sites. Another significant fraction of Fe dopant ions is in 4+ oxidation state and a still smaller fraction might be existing as Fe{sup 2+} ions, both occupying distorted sites, presumably in the surface regions of the nanocrystals, near oxygen vacancies. These studies also suggest that the observed magnetism is not due to exchange coupling between Fe{sup 3+} spins. A more probable role for the multi-valent Fe ions may be to act as charge reservoirs, leading to charge transfer ferromagnetism.

  17. Controlling the magnetization reversal in exchange-biased Co/CoO elongated nanorings This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Adeyeye, Adekunle

    of Western Australia, Crawley, WA 6009, Australia E-mail: eleaao@nus.edu.sg Received 15 September 2008 head-on (180 ) domain walls [2]. Due to elimination of the high energy vortex core, the vortex state

  18. Maxwell's fluid model of magnetism

    E-Print Network [OSTI]

    Robert Brady; Ross Anderson

    2015-02-20T23:59:59.000Z

    In 1861, Maxwell derived two of his equations of electromagnetism by modelling a magnetic line of force as a `molecular vortex' in a fluid-like medium. Later, in 1980, Berry and colleagues conducted experiments on a `phase vortex', a wave geometry in a fluid which is analogous to a magnetic line of force and also exhibits behaviour corresponding to the quantisation of magnetic flux. Here we unify these approaches by writing down a solution to the equations of motion for a compressible fluid which behaves in the same way as a magnetic line of force. We then revisit Maxwell's historical inspiration, namely Faraday's 1846 model of light as disturbances in lines of force. Using our unified model, we show that such disturbances resemble photons: they are polarised, absorbed discretely, obey Maxwell's full equations of electromagnetism to first order, and quantitatively reproduce the correlation that is observed in the Bell tests.

  19. Convergenceof Vortex Methods for Weak Solutionsto the

    E-Print Network [OSTI]

    Liu, Jian-Guo

    , Krasny applied such a method in his calculations of the evolution of vortex sheetseven past the time when numerical simulations;see Krasny, [16] and [17], and Baker and Shelley, [l]. It is thus important to analyze by Krasny (see [16] and [17]). Our analysis is closely related to that of [9], [lo], and [18], and based

  20. Quenching Processes in Flame-Vortex Interactions

    E-Print Network [OSTI]

    Zingale, Michael

    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

  1. Effect of a magnetic field on the instability of the nonequilibrium state of superconducting Nb films in the case of tunnel injection of quasi-particles

    SciTech Connect (OSTI)

    Pan, V.; Rudenko, E.; Nevirkovets, I.; Shaternik, V.

    1981-11-01T23:59:59.000Z

    The effect of an external magnetic field on the instability of the nonequilibrium state of superconducting films of niobium when there is tunnel injection of quasi-particles has been studied and it was shown that increasing the magnetic field reduces the value of the instability current. (AIP)

  2. Analytical Tendex and Vortex Fields for Perturbative Black Hole Initial Data

    E-Print Network [OSTI]

    Kenneth A. Dennison; Thomas W. Baumgarte

    2012-07-10T23:59:59.000Z

    Tendex and vortex fields, defined by the eigenvectors and eigenvalues of the electric and magnetic parts of the Weyl curvature tensor, form the basis of a recently developed approach to visualizing spacetime curvature. In particular, this method has been proposed as a tool for interpreting results from numerical binary black hole simulations, providing a deeper insight into the physical processes governing the merger of black holes and the emission of gravitational radiation. Here we apply this approach to approximate but analytical initial data for both single boosted and binary black holes. These perturbative data become exact in the limit of small boost or large binary separation. We hope that these calculations will provide additional insight into the properties of tendex and vortex fields, and will form a useful test for future numerical calculations.

  3. Charge state control in single InAs/GaAs quantum dots by external electric and magnetic fields

    SciTech Connect (OSTI)

    Tang, Jing [Institute of Photo-electronic Thin Film Devices and Technology, Nankai University, Tianjin 300071 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Cao, Shuo; Gao, Yunan; Sun, Yue; Jin, Kuijuan; Xu, Xiulai, E-mail: xlxu@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Geng, Weidong, E-mail: gengwd@nankai.edu.cn [Institute of Photo-electronic Thin Film Devices and Technology, Nankai University, Tianjin 300071 (China); Williams, David A. [Hitachi Cambridge Laboratory, Cavendish Laboratory, Cambridge CB3 0HE (United Kingdom)

    2014-07-28T23:59:59.000Z

    We report a photoluminescence (PL) spectroscopy study of charge state control in single self-assembled InAs/GaAs quantum dots by applying electric and/or magnetic fields at 4.2?K. Neutral and charged exciton complexes were observed under applied bias voltages from ?0.5?V to 0.5?V by controlling the carrier tunneling. The highly negatively charged exciton emission becomes stronger with increasing pumping power, arising from the fact that electrons have a smaller effective mass than holes and are more easily captured by the quantum dots. The integrated PL intensity of negatively charged excitons is affected significantly by a magnetic field applied along the sample growth axis. This observation is explained by a reduction in the electron drift velocity caused by an applied magnetic field, which increases the probability of non-resonantly excited electrons being trapped by localized potentials at the wetting layer interface, and results in fewer electrons distributed in the quantum dots. The hole drift velocity is also affected by the magnetic field, but it is much weaker.

  4. Journal of Magnetism and Magnetic Materials 288 (2005) 196204 Micromagnetic studies of nickel microbars fabricated by

    E-Print Network [OSTI]

    Pesic, Batric

    2005-01-01T23:59:59.000Z

    Abstract Micromagnetic configurations and macromagnetic properties of electrodeposited nickel microbars: 75.50.Cc; 75.75.+a; 81.15.Pq Keywords: Electrodeposited nickel; Magnetic microbar; Magnetic vortex (VSM) studies of nickel microbars with round corners, produced by nanoimprinting and electrodeposition

  5. Coherent quantum states of a relativistic particle in an electromagnetic plane wave and a parallel magnetic field

    SciTech Connect (OSTI)

    Colavita, E. [Colegio de Ciencia y Tecnología, Universidad Autónoma de la Ciudad de México, México, D.F., 09790 (Mexico)] [Colegio de Ciencia y Tecnología, Universidad Autónoma de la Ciudad de México, México, D.F., 09790 (Mexico); Hacyan, S., E-mail: hacyan@fisica.unam.mx [Instituto de Física, Universidad Nacional Autónoma de México, A. P. 20-364, México D. F., 01000 (Mexico)

    2014-03-15T23:59:59.000Z

    We analyze the solutions of the Klein–Gordon and Dirac equations describing a charged particle in an electromagnetic plane wave combined with a magnetic field parallel to the direction of propagation of the wave. It is shown that the Klein–Gordon equation admits coherent states as solutions, while the corresponding solutions of the Dirac equation are superpositions of coherent and displaced-number states. Particular attention is paid to the resonant case in which the motion of the particle is unbounded. -- Highlights: •We study a relativistic electron in a particular electromagnetic field configuration. •New exact solutions of the Klein–Gordon and Dirac equations are obtained. •Coherent and displaced number states can describe a relativistic particle.

  6. Edge states in graphene quantum dots: Fractional quantum Hall effect analogies and differences at zero magnetic field

    E-Print Network [OSTI]

    Igor Romanovsky; Constantine Yannouleas; Uzi Landman

    2009-01-15T23:59:59.000Z

    We investigate the way that the degenerate manifold of midgap edge states in quasicircular graphene quantum dots with zig-zag boundaries supports, under free-magnetic-field conditions, strongly correlated many-body behavior analogous to the fractional quantum Hall effect (FQHE), familiar from the case of semiconductor heterostructures in high magnetic fields. Systematic exact-diagonalization (EXD) numerical studies are presented for the first time for 5 graphene REMs exhibit in all instances a single (0,N) polygonal-ring molecular (crystalline) structure, with all the electrons localized on the edge. Disruptions in the zig-zag boundary condition along the circular edge act effectively as impurities that pin the electron molecule, yielding single-particle densities with broken rotational symmetry that portray directly the azimuthal localization of the edge electrons.

  7. Strings, vortex rings, and modes of instability

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Gubser, Steven S.; Nayar, Revant; Parikh, Sarthak

    2015-03-01T23:59:59.000Z

    We treat string propagation and interaction in the presence of a background Neveu–Schwarz three-form field strength, suitable for describing vortex rings in a superfluid or low-viscosity normal fluid. A circular vortex ring exhibits instabilities which have been recognized for many years, but whose precise boundaries we determine for the first time analytically in the small core limit. Two circular vortices colliding head-on exhibit stronger instabilities which cause splitting into many small vortices at late times. We provide an approximate analytic treatment of these instabilities and show that the most unstable wavelength is parametrically larger than a dynamically generated length scalemore »which in many hydrodynamic systems is close to the cutoff. We also summarize how the string construction we discuss can be derived from the Gross–Pitaevskii Lagrangian, and also how it compares to the action for giant gravitons.« less

  8. Deterministic Josephson Vortex Ratchet with a load

    E-Print Network [OSTI]

    M. Knufinke; K. Ilin; M. Siegel; D. Koelle; R. Kleiner; E. Goldobin

    2011-09-29T23:59:59.000Z

    We investigate experimentally a deterministic underdamped Josephson vortex ratchet -- a fluxon-particle moving along a Josephson junction in an asymmetric periodic potential. By applying a sinusoidal driving current one can compel the vortex to move in a certain direction, producing average dc voltage across the junction. Being in such a rectification regime we also load the ratchet, i.e., apply an additional dc bias current I_dc (counterforce) which tilts the potential so that the fluxon climbs uphill due to the ratchet effect. The value of the bias current at which the fluxon stops climbing up defines the strength of the ratchet effect and is determined experimentally. This allows us to estimate the loading capability of the ratchet, the output power and efficiency. For the quasi-static regime we present a simple model which delivers simple analytic expressions for the above mentioned figures of merit.

  9. Multiple precision, multiple processor vortex sheet roll-up computation

    SciTech Connect (OSTI)

    Bailey, D.H. [NASA Ames Research Center, Moffett Field, CA (United States); Krasny, R. [Univ. of Michigan, Ann Arbor, MI (United States); Pelz, R. [Rutgers Univ., Piscataway, NJ (United States)

    1993-12-31T23:59:59.000Z

    A vortex sheet in incompressible flow is a surface across which the tangential fluid velocity has a jump discontinuity. A basic idea in fluid dynamics going back to Prandtl is that the vortex sheet can be obtained as the zero viscosity limit of a sequence of smooth solutions to the Navier-Stokes equations. Thus, the investigation of vortex sheet motion may yield insight into the structure of high Reynolds number flow.

  10. Optical vortex interaction and generation via nonlinear wave mixing

    SciTech Connect (OSTI)

    Lenzini, F. [INLN, Universite de Nice-Sophia Antipolis, CNRS, 1361 route des Lucioles, FR-06560 Valbonne (France); Dipartimento di Fisica, Universita di Firenze, via Sansone 1, IT-50019 Sesto Fiorentino (Italy); Residori, S.; Bortolozzo, U. [INLN, Universite de Nice-Sophia Antipolis, CNRS, 1361 route des Lucioles, FR-06560 Valbonne (France); Arecchi, F. T. [Dipartimento di Fisica, Universita di Firenze, via Sansone 1, IT-50019 Sesto Fiorentino (Italy)

    2011-12-15T23:59:59.000Z

    Optical vortex beams are made to interact via degenerate two-wave mixing in a Kerr-like nonlinear medium. Vortex mixing is shown to occur inside the medium, leading to exchange of topological charge and cascaded generation of vortex beams. A mean-field model is developed and is shown to account for the selection rules of the topological charges observed after the wave-mixing process. Fractional charges are demonstrated to follow the same rules as for integer charges.

  11. Laboratory Analysis of Vortex Dynamics For Shallow Tidal Inlets

    E-Print Network [OSTI]

    Whilden, Kerri Ann

    2010-10-12T23:59:59.000Z

    of the secondary structures into the vortex system are shown as well as variations in characteristics such as trajectory, size, vorticity, and circulation for the vortices as they move downstream. iv To the loved ones who have encouraged me along the way. v.... : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 30 13 Non-Dimensional Vorticity at the Swirl Strength Peak for the Pri- mary Vortex Within the Vortex System Versus Non-Dimensional Horizontal Location of the Centroid. : : : : : : : : : : : : : : : : : : 31 14 Non-Dimensional Circulation...

  12. active vortex generators: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    how an initial dusturbing cyclonic vortex is created by collision between two linear wind jets under certain conditions, which under favorable conditions, may mature into a...

  13. Magnetic Vortex Core Reversal by Low-Field Excitations

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    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...

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

    SciTech Connect (OSTI)

    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

    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.

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

    SciTech Connect (OSTI)

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

    2003-12-01T23:59:59.000Z

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

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

    E-Print Network [OSTI]

    Moshchalkov, Victor V.

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

  17. National High Magnetic Field Laboratory 2010 ANNUAL REPORTFlorida State University University of Florida Los Alamos National Lab

    E-Print Network [OSTI]

    Weston, Ken

    RESEARCH HIGHLIGHTS: CONDENSED MATTER SCIENCE Technique development, graphene, magnetism & magnetic tenth year of operation, continued its essential role in graphene exploration. Interest has also

  18. Center Manifold Analysis of a PointVortex Model of Vortex Shedding with Control

    E-Print Network [OSTI]

    Protas, Bartosz

    of the point vortex F¨oppl system with linear feedback control. The F¨oppl system was used in an earlier system. Key words: point vortices, flow control, dynamical systems, wake flows PACS: 47.15.Hg, 47.27.Rc, 47.27.Vf 1 Introduction Integration of rigorous methods of Modern Control Theory with Computational

  19. Structure and dynamics studies by solid-state nuclear magnetic resonance spectroscopy

    E-Print Network [OSTI]

    Itin, Boris

    2002-01-01T23:59:59.000Z

    The major goal of this work is the development of high resolution solid state 205T1 NMR techniques and their application to the elucidation of the mechanism and dynamics of ion exchange in biological solids. The thesis ...

  20. Center Vortex vs. Abelian models of the QCD vacuum

    E-Print Network [OSTI]

    Höllwieser, Roman

    2015-01-01T23:59:59.000Z

    We present evidence that the center vortex model of confinement is more consistent with lattice results than other currently available models. In particular we show that Abelian field distributions predicted by monopole plasma, caloron gas or dual superconductor models cannot reproduce the area-law falloff of double winding Wilson loops in full $SU(2)$ and center vortex only gauge fields.

  1. Vortex Lattice Modelling of Winglets on Wind Turbine Blades

    E-Print Network [OSTI]

    Vortex Lattice Modelling of Winglets on Wind Turbine Blades Mads Døssing Risø-R-1621(EN) Risø Title: Vortex Lattice Modelling of Winglets on Wind Turbine Blades Departments: Wind Energy Department turbines can be increased by the use of winglets without increasing the swept area. This makes them

  2. Geometrical statistics and vortex structures in helical and nonhelical turbulences

    E-Print Network [OSTI]

    Li, Yi

    , United Kingdom Received 4 August 2009; accepted 20 January 2010; published online 9 March 2010 explained in terms of the self-induced motions of local vortex structures, which tend to wind up the vortex­11,13­15 the effects of helicity on energy cascade,16 the interaction between helicity and energy dissipation,17

  3. Magnetic moments of Coulomb excited $2^{+}_{1}$ states for radioactive beams of $^{132,134,136}$Te and $^{138}$Xe isotopes at REX-ISOLDE Status Report on the Experiment IS415 at CERN

    E-Print Network [OSTI]

    CERN. Geneva. ISOLDE and Neutron Time-of-Flight Experiments Committee; Speidel, K H; Fraile-Prieto, L M; Balabanski, D L; Behrens, T; Georgiev, G; Gerber, J P; Gernhäuser, R; Kröll, T; Krücken, R; Leske, J; Lo Bianco, G; Lutter, R; Maier-Komor, P; Modamio, V; Schielke, S; Walker, J

    2006-01-01T23:59:59.000Z

    Magnetic moments of Coulomb excited $2^{+}_{1}$ states for radioactive beams of $^{132,134,136}$Te and $^{138}$Xe isotopes at REX-ISOLDE

  4. Vortex Oscillation Technology Ltd | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov YouKizildere IRaghuraji Agro IndustriesTown of Ladoga,planningFlowmeterUtah: Energydba Vision MotorVolusiaVortex

  5. Vortex Hydro Energy LLC | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are beingZealand Jump to:Ezfeedflag JumpID-fTri Global EnergyUtility RateVirginia/WindCounty, California |Vortex Hydro

  6. Large-scale molecular dynamics simulation of magnetic properties of amorphous iron under pressure

    E-Print Network [OSTI]

    ) Enhanced refrigerant capacity and magnetic entropy flattening using a two-amorphous FeZrB(Cu) compositeLarge-scale molecular dynamics simulation of magnetic properties of amorphous iron under pressure Appl. Phys. Lett. 99, 232501 (2011) Nonlinear motion of magnetic vortex under alternating

  7. Accepted Dec. 2102 _Solid State Sciences First principles study of the electronic and magnetic structures and

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    to high linear incompressibility. Relevant features of selective bonding of uranium and cobalt with carbon. A ferromagnetic ground state is proposed from the calculations. Keywords Uranium cobalt di-carbide. Electronic Structure. EOS. Bonding. * Correspondence: matar@icmcb-bordeaux.cnrs.fr hal-00785221,version1-23Apr2013

  8. American Institute of Aeronautics and Astronautics Numerical Investigation of the Evolution of Vortex

    E-Print Network [OSTI]

    Rohde, Axel

    and 1000 diameters, alternate vortex shedding begins, and a von Karman vortex street develops in the wake of Vortex Instability in a 2-D Compressible Flow over a Cylinder Axel Rohde Department of Aerospace start and reveals the evolution of vortex instability. After the cylinder has traveled between 100

  9. Non-Riemannian geometry of vortex acoustics

    SciTech Connect (OSTI)

    Garcia de Andrade, L.C. [Departamento de Fisica Teorica, Instituto de Fisica, Universidade Estadual do Rio de Janeiro, Rua Sao Francisco Xavier 524, Maracana, 20550, Rio de Janeiro, RJ (Brazil)

    2004-09-15T23:59:59.000Z

    The concept of acoustic torsion is introduced by making use of the scalar wave equation in Riemann-Cartan spacetime. Acoustic torsion extends the acoustic metric previously given by Unruh (PRL-1981). The wave equation describes irrotational perturbations in rotational nonrelativistic fluids. This physical motivation allows us to show that the acoustic line element can be conformally mapped to the line element of a stationary torsion loop in non-Riemannian gravity. Two examples of such sonic analogues are given. The first is the stationary torsion loop in teleparallel gravity. In the far from the vortex approximation, the Cartan torsion vector is shown to be proportional to the quantum vortex number of the superfluid. The torsion vector is also shown to be proportional to the superfluid vorticity in the presence of vortices. The formation of superfluid vortices is shown not to be favored by torsion loops in Riemann-Cartan spacetime, as long as this model is concerned. It is suggested that the teleparallel model may help to find a model for superfluid neutron stars vortices based on non-Riemannian gravity.

  10. Magnets & Magnet Condensed Matter Science

    E-Print Network [OSTI]

    McQuade, D. Tyler

    18 No. 1 CONDENSED MATTER SCIENCE Technique development, graphene, magnetism & magnetic materials Pressure 9 Metal to Insulator Transition on the N=0 Landau Level in Graphene 10 Evidence for Fractional Quantum Hall States in Suspended Bilayer and Trilayer Graphene 11 Fractional Quantum Hall Effect

  11. Rotational response of superconductors: magneto-rotational isomorphism and rotation-induced vortex lattice

    E-Print Network [OSTI]

    Egor Babaev; Boris Svistunov

    2014-03-03T23:59:59.000Z

    The analysis of nonclassical rotational response of superfluids and superconductors was performed by Onsager (in 1949) \\cite{Onsager} and London (in 1950) \\cite{London} and crucially advanced by Feynman (in 1955) \\cite{Feynman}. It was established that, in thermodynamic limit, neutral superfluids rotate by forming---without any threshold---a vortex lattice. In contrast, the rotation of superconductors at angular frequency ${\\bf \\Omega}$---supported by uniform magnetic field ${\\bf B}_L\\propto {\\bf \\Omega}$ due to surface currents---is of the rigid-body type (London Law). Here we show that, neglecting the centrifugal effects, the behavior of a rotating superconductor is identical to that of a superconductor placed in a uniform fictitious external magnetic filed $\\tilde{\\bf H}=- {\\bf B}_L$. In particular, the isomorphism immediately implies the existence of two critical rotational frequencies in type-2 superconductors.

  12. Solid-State Nuclear Magnetic Resonance Evidence for Parallel and Antiparallel Strand Arrangements in the Membrane-Associated HIV-1 Fusion Peptide

    E-Print Network [OSTI]

    Weliky, David

    Solid-State Nuclear Magnetic Resonance Evidence for Parallel and Antiparallel Strand Arrangements in the Membrane-Associated HIV-1 Fusion Peptide Jun Yang and David P. Weliky* Department of Chemistry, Michigan 7, 2003 ABSTRACT: The HIV-1 fusion peptide serves as a useful model system for understanding viral

  13. Supported by the National Science Foundation and the State of Florida 1 REPORTSNATIONAL HIGH MAGNETIC FIELD LABORATORY

    E-Print Network [OSTI]

    Weston, Ken

    .S. Shvindlerman3 Magnetic Driving Force cont. on page 6 N H M F L M a g n e t s Engineered for Unique Needs and Sometimes Unworldly Destinations In the first years of the laboratory, NHMFL magnet engineers, designers of magnets engineered to the specific needs of customers. Typically when crystals are grown, the presence

  14. Sound Wave in Vortex with Sink

    E-Print Network [OSTI]

    Soumen Basak

    2003-11-17T23:59:59.000Z

    Using Komar's definition, we give expressions for the mass and angular momentum of a rotating acoustic black hole. We show that the mass and angular momentum so defined, obey the equilibrium version of the first law of Black Hole thermodynamics. We also show that when a phonon passes by a vortex with a sink, its trajectory is bent. The angle of bending of the sound wave to leading order is quadratic in $A/cb$ and $B/cb$, where $b$ is the impact parameter and $A$ and $B$ are the parameters in the velocity of the fluid flow. The time delay in the propagation of sound wave which to first order depends only on $B/c^2$ and is independent of $A$.

  15. Fuel injection of coal slurry using vortex nozzles and valves

    DOE Patents [OSTI]

    Holmes, Allen B. (Rockville, MD)

    1989-01-01T23:59:59.000Z

    Injection of atomized coal slurry fuel into an engine combustion chamber is achieved at relatively low pressures by means of a vortex swirl nozzle. The outlet opening of the vortex nozzle is considerably larger than conventional nozzle outlets, thereby eliminating major sources of failure due to clogging by contaminants in the fuel. Control fluid, such as air, may be used to impart vorticity to the slurry and/or purge the nozzle of contaminants during the times between measured slurry charges. The measured slurry charges may be produced by a diaphragm pump or by vortex valves controlled by a separate control fluid. Fluidic circuitry, employing vortex valves to alternatively block and pass cool slurry fuel flow, is disclosed.

  16. Zero-Energy Flows and Vortex Patterns in Quantum Mechanics

    E-Print Network [OSTI]

    Tsunehiro Kobayashi

    2003-02-20T23:59:59.000Z

    We show that zero-energy flows appear in many particle systems as same as in single particle cases in 2-dimensions. Vortex patterns constructed from the zero-energy flows can be investigated in terms of the eigenstates in conjugate spaces of Gel'fand triplets. Stable patterns are written by the superposition of zero-energy eigenstates. On the other hand vortex creations and annihilations are described by the insertions of unstable eigenstates with complex-energy eigenvalues into the stable patterns. Some concrete examples are presented in the 2-dimensional parabolic potential barrier case. %, i.e., $-m \\gamma^2 (x^2+y^2)/2$. We point out three interesting properties of the zero-energy flows; (i) the absolute economy as for the energy consumption, (ii) the infinite variety of the vortex patterns, and (iii) the absolute stability of the vortex patterns .

  17. axisymmetric vortex breakdown: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Fluid Motion at the 66th Annual Meeting of the APS Division of Fluid Dynamics. Kleckner, Dustin; Irvine, William T M 2013-01-01 325 The Taylor-vortex dynamo Christophe Gissinger...

  18. Vortex-induced vibration of slender structures in unsteady flow

    E-Print Network [OSTI]

    Liao, Jung-Chi, 1971-

    2002-01-01T23:59:59.000Z

    Vortex-induced vibration (VIV) results in fatigue damage of offshore oil exploration and production structures. In recent years, the offshore industry has begun to employ curved slender structures such as steel catenary ...

  19. Drag amplification and fatigue damage in vortex-induced vibrations

    E-Print Network [OSTI]

    Jhingran, Vikas Gopal

    2008-01-01T23:59:59.000Z

    Fatigue damage and drag force amplification due to Vortex-Induced-Vibrations (VIV) continue to cause significant problems in the design of structures which operate in ocean current environments. These problems are magnified ...

  20. Vortex hair on AdS black holes

    E-Print Network [OSTI]

    Gregory, Ruth; Kubiznak, David; Mann, Robert B; Wills, Danielle

    2014-01-01T23:59:59.000Z

    We analyse vortex hair for charged rotating asymptotically AdS black holes in the abelian Higgs model. We give analytical and numerical arguments to show how the vortex interacts with the horizon of the black hole, and how the solution extends to the boundary. The solution is very close to the corresponding asymptotically flat vortex, once one transforms to a frame that is non-rotating at the boundary. We show that there is a Meissner effect for extremal black holes, with the vortex flux being expelled from sufficiently small black holes. The phase transition is shown to be first order in the presence of rotation, but second order without rotation. We comment on applications to holography.

  1. Nonclassicality of vortex Airy beams in the Wigner representation

    SciTech Connect (OSTI)

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

    2011-10-15T23:59:59.000Z

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

  2. Magnetic shielding

    DOE Patents [OSTI]

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

    1985-02-12T23:59:59.000Z

    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.

  3. Substitution of Ni for Fe in superconducting Fe?.??Te?.?Se?.? depresses the normal-state conductivity but not the magnetic spectral weight

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Jinghui; Tranquada, J. M.; Zhong, Ruidan; Li, Shichao; Gan, Yuan; Xu, Zhijun; Zhang, Cheng; Ozaki, T.; Matsuda, M.; Zhao, Yang; et al

    2015-01-01T23:59:59.000Z

    We have performed systematic resistivity and inelastic neutron scattering measurements on Fe?.???zNizTe?.?Se?.? samples to study the impact of Ni substitution on the transport properties and the low-energy (? 12 meV) magnetic excitations. It is found that, with increasing Ni doping, both the conductivity and superconductivity are gradually suppressed; in contrast, the low-energy magnetic spectral weight changes little. Comparing with the impact of Co and Cu substitution, we find that the effects on conductivity and superconductivity for the same degree of substitution grow systematically as the atomic number of the substituent deviates from that of Fe. The impact of the substituentsmore »as scattering centers appears to be greater than any contribution to carrier concentration. The fact that low-energy magnetic spectral weight is not reduced by increased electron scattering indicates that the existence of antiferromagnetic correlations does not depend on electronic states close to the Fermi energy.« less

  4. Substitution of Ni for Fe in superconducting Fe?.??Te?.?Se?.? depresses the normal-state conductivity but not the magnetic spectral weight

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Jinghui [Nanjing Univ., Nanjing (China); Tranquada, J. M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zhong, Ruidan [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States); Li, Shichao [Nanjing Univ., Nanjing (China); Gan, Yuan [Nanjing Univ., Nanjing (China); Xu, Zhijun [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zhang, Cheng [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States); Ozaki, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Matsuda, M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhao, Yang [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Univ. of Maryland, College Park, MD (United States); Li, Qiang [Brookhaven National Lab. (BNL), Upton, NY (United States); Xu, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gu, Genda [Brookhaven National Lab. (BNL), Upton, NY (United States); Birgeneau, R. J. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wen, Jinsheng [Nanjing Univ., Nanjing (China)

    2015-01-01T23:59:59.000Z

    We have performed systematic resistivity and inelastic neutron scattering measurements on Fe?.???zNizTe?.?Se?.? samples to study the impact of Ni substitution on the transport properties and the low-energy (? 12 meV) magnetic excitations. It is found that, with increasing Ni doping, both the conductivity and superconductivity are gradually suppressed; in contrast, the low-energy magnetic spectral weight changes little. Comparing with the impact of Co and Cu substitution, we find that the effects on conductivity and superconductivity for the same degree of substitution grow systematically as the atomic number of the substituent deviates from that of Fe. The impact of the substituents as scattering centers appears to be greater than any contribution to carrier concentration. The fact that low-energy magnetic spectral weight is not reduced by increased electron scattering indicates that the existence of antiferromagnetic correlations does not depend on electronic states close to the Fermi energy.

  5. Substitution of Ni for Fe in superconducting Fe?.??Te?.?Se?.? depresses the normal-state conductivity but not the magnetic spectral weight

    SciTech Connect (OSTI)

    Wang, Jinghui [Nanjing Univ., Nanjing (China); Tranquada, J. M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zhong, Ruidan [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States); Li, Shichao [Nanjing Univ., Nanjing (China); Gan, Yuan [Nanjing Univ., Nanjing (China); Xu, Zhijun [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Zhang, Cheng [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States); Ozaki, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Matsuda, M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Zhao, Yang [National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Univ. of Maryland, College Park, MD (United States); Li, Qiang [Brookhaven National Lab. (BNL), Upton, NY (United States); Xu, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gu, Genda [Brookhaven National Lab. (BNL), Upton, NY (United States); Birgeneau, R. J. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wen, Jinsheng [Nanjing Univ., Nanjing (China)

    2015-01-01T23:59:59.000Z

    We have performed systematic resistivity and inelastic neutron scattering measurements on Fe?.???zNizTe?.?Se?.? samples to study the impact of Ni substitution on the transport properties and the low-energy (? 12 meV) magnetic excitations. It is found that, with increasing Ni doping, both the conductivity and superconductivity are gradually suppressed; in contrast, the low-energy magnetic spectral weight changes little. Comparing with the impact of Co and Cu substitution, we find that the effects on conductivity and superconductivity for the same degree of substitution grow systematically as the atomic number of the substituent deviates from that of Fe. The impact of the substituents as scattering centers appears to be greater than any contribution to carrier concentration. The fact that low-energy magnetic spectral weight is not reduced by increased electron scattering indicates that the existence of antiferromagnetic correlations does not depend on electronic states close to the Fermi energy.

  6. Vortex and structural dynamics of a flexible cylinder in cross-flow

    SciTech Connect (OSTI)

    Shang, Jessica K., E-mail: jshang@princeton.edu; Stone, Howard A. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Smits, Alexander J. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Monash University, VIC 3800 (Australia)

    2014-05-15T23:59:59.000Z

    A low-density, flexible cantilevered cylinder was permitted to vibrate freely under the influence of vortex shedding in the laminar flow regime. We find that the vortex-induced vibrations (VIV) of a flexible cantilever depart from those of a flexible cylinder that is fixed at both ends. In particular, we find discontinuous regions of VIV behavior – here called states – as a function of the reduced velocity U{sup *}. These states are demarcated by discrete changes in the dominant eigenmodes of the structural response as the cylinder vibrates in progressively higher structural modes with increasing U{sup *}. The contribution of structural modes can be identified readily by a modal projection of the cylinder oscillation onto known cantilever beam modes. Oscillation frequencies do not monotonically increase with U{sup *}. The wake response between different states is also found to have distinct characteristics; of particular note is the occurrence of a P+S wake over one of these regions, which is associated with a high-amplitude vibration of the cylinder that is due to the constructive interference of contributing eigenmodes.

  7. Arrays of nanoscale magnetic dots: Fabrication by x-ray interference lithography and characterization

    SciTech Connect (OSTI)

    Heyderman, L.J.; Solak, H.H.; David, C.; Atkinson, D.; Cowburn, R.P.; Nolting, F. [Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Nanomagnetism Group, Department of Physics, University of Durham, Rochester Building, Science Laboratories, South Road, Durham DH1 3LE (United Kingdom); Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

    2004-11-22T23:59:59.000Z

    X-ray interference lithography (XIL) was employed in combination with electrodeposition to fabricate arrays of nanoscale nickel dots which are uniform over 40 {mu}m and have periods down to 71 nm. Using extreme-ultraviolet light, XIL has the potential to produce magnetic dot arrays over large areas with periods well below 50 nm, and down to a theoretical limit of 6.5 nm for a 13 nm x-ray wavelength. In the nickel dot arrays, we observed the effect of interdot magnetic stray field interactions. Measuring the hysteresis loops using the magneto-optical Kerr effect, a double switching via the vortex state was observed in the nickel dots with diameters down to 44 nm and large dot separations. As the dot separations are reduced to below around 50 nm a single switching, occurring by collective rotation of the magnetic spins, is favored due to interdot magnetic stray field interactions. This results in magnetic flux closure through several dots which could be visualized with micromagnetic simulations. Further evidence of the stray field interactions was seen in photoemission electron microscopy images, where bands of contrast corresponding to chains of coupled dots were observed.

  8. Bound states for a Coulomb-type potential induced by the interaction between a moving electric quadrupole moment and a magnetic field

    SciTech Connect (OSTI)

    Bakke, K., E-mail: kbakke@fisica.ufpb.br

    2014-02-15T23:59:59.000Z

    We discuss the arising of bound states solutions of the Schrödinger equation due to the presence of a Coulomb-type potential induced by the interaction between a moving electric quadrupole moment and a magnetic field. Furthermore, we study the influence of the Coulomb-type potential on the harmonic oscillator by showing a quantum effect characterized by the dependence of the angular frequency on the quantum numbers of the system, whose meaning is that not all values of the angular frequency are allowed. -- Highlights: • Interaction between a moving electric quadrupole moment and a magnetic field. • Arising of bound states solutions due to the presence of a Coulomb-type potential. • Influence of the Coulomb-type potential on the harmonic oscillator. • Dependence of the angular frequency on the quantum numbers of the system.

  9. Alleviation of fuselage form drag using vortex flows: Final report

    SciTech Connect (OSTI)

    Wortman, A.

    1987-09-15T23:59:59.000Z

    The concept of using vortex generators to reduce the fuselage form drag of transport aircraft combines the outflow from the plane of symmetry which is induced by the rotational component of the vortex flow with the energization of the boundary layer to reduce the momentum thickness and to delay or eliminate flow separation. This idea was first advanced by the author in 1981. Under a DOE grant, the concept was validated in wind tunnel tests of approximately 1:17 scale models of fuselages of Boeing 747 and Lockheed C-5 aircraft. The search for the minimum drag involved three vortex generator configurations with three sizes of each in six locations clustered in the aft regions of the fuselages at the beginning of the tail upsweep. The local Reynolds number, which is referred to the length of boundary layer run from the nose, was approximately 10{sup 7} so that a fully developed turbulent boundary layer was present. Vortex generator planforms ranged from swept tapered, through swept straight, to swept reverse tapered wings whose semi-spans ranged from 50% to 125% of the local boundary layer thickness. Pitch angles of the vortex generators were varied by inboard actuators under the control of an external proportional digital radio controller. It was found that certain combinations of vortex generator parameters increased drag. However, with certain configurations, locations, and pitch angles of vortex generators, the highest drag reductions were 3% for the 747 and about 6% for the C-5, thus confirming the arguments that effectiveness increases with the rate of upsweep of the tail. Greatest gains in performance are therefore expected on aft loading military transports. 10 refs., 11 figs., 1 tab.

  10. Supported by the National Science Foundation and the State of Florida 1 REPORTSNATIONAL HIGH MAGNETIC FIELD LABORATORY

    E-Print Network [OSTI]

    Weston, Ken

    National Laboratory Power Supplies Installed for Quasi-Continuous Magnet at LANL Power converters five 64 MW converters. The liquid nitrogen cooled magnet, which will be the most powerful of its class, to be completed later. Power Supply Design Each power converter is supplied with 21 kV from the 1430 MVA / 600 MJ

  11. Evaluation of the energy states of hydrogen atom using Schroedinger equation with a Coulomb potential modified by the interaction between the magnetic moments of the proton and electron

    E-Print Network [OSTI]

    Voicu Dolocan

    2014-04-06T23:59:59.000Z

    In this paper we have performed the calculus of the energy states of hydrogen atom by using the Schroedinger equation with a Coulomb potential which is modified by the interaction between the magnetic moments of the proton and the electron, respectively. The important result is that the Lamb shift appears as a natural result of the solution of Schroedinger equation. The obtained results are in a good agreement with experimental data.

  12. A PARAMETER STUDY FOR BAROCLINIC VORTEX AMPLIFICATION

    SciTech Connect (OSTI)

    Raettig, Natalie; Klahr, Hubert [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Lyra, Wladimir, E-mail: raettig@mpia.de, E-mail: klahr@mpia.de, E-mail: Wladimir.Lyra@jpl.nasa.gov [Department of Astrophysics, American Museum of Natural History, 79th Street at Central Park West, New York, NY 10024 (United States)

    2013-03-10T23:59:59.000Z

    Recent studies have shown that baroclinic vortex amplification is strongly dependent on certain factors, namely, the global entropy gradient, the efficiency of thermal diffusion and/or relaxation as well as numerical resolution. We conduct a comprehensive study of a broad range and combination of various entropy gradients, thermal diffusion and thermal relaxation timescales via local shearing sheet simulations covering the parameter space relevant for protoplanetary disks. We measure the Reynolds stresses as a function of our control parameters and see that there is angular momentum transport even for entropy gradients as low as {beta} = -dln s/dln r = 1/2. Values we expect in protoplanetary disks are between {beta} = 0.5-2.0 The amplification-rate of the perturbations, {Gamma}, appears to be proportional to {beta}{sup 2} and thus proportional to the square of the Brunt-Vaeisaelae frequency ({Gamma}{proportional_to}{beta}{sup 2}{proportional_to}N {sup 2}). The saturation level of Reynolds stresses, on the other hand, seems to be proportional to {beta}{sup 1/2}. This highlights the importance of baroclinic effects even for the low entropy gradients expected in protoplanetary disks.

  13. Ultra-Low NOx Advanced Vortex Combustor

    SciTech Connect (OSTI)

    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

    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.

  14. ULTRA-LOW NOX ADVANCED VORTEX COMBUSTOR

    SciTech Connect (OSTI)

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

    2006-05-01T23:59:59.000Z

    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.

  15. Proton Dynamics in ZnO Nanorods Quantified by In Situ Solid-State 1H Nuclear Magnetic Resonance

    SciTech Connect (OSTI)

    Wang, Li Q.; Zhou, Xiao Dong; Exarhos, Gregory J.; Pederson, Larry R.; Wang, Chong M.; Windisch, Charles F.; Yao, Chunhua

    2007-10-22T23:59:59.000Z

    Zinc oxide (ZnO) adopts wurtzite structure and possesses a direct wide band gap (Eg ~ 3.3 eV at 300 K), similar to that of GaN (Eg ~ 3.4 eV at 300 K), which enables ZnO as an alternative candidate to replace GaN for use in optoelectronic devices. The present controversy is centered at the microscopic origin of the “native donors”, particularly after ab initio calculations by Van de Walle, which indicate that hydrogen is soluble in ZnO at the interstitial sites, effectively forming a donor level just below the conduction band in ZnO. Hence, the origin of n type conductivity in ZnO is proposed due to the presence of hydrogen. Electron paramagnetic resonance and spectroscopic observations of muons provide experimental evidence of hydrogen presence in ZnO. Whereas, Look et al. suggests that the complex of zinc interstitial and nitrogen defect is a stronger candidate for donor than hydrogen interstitials under N ambient. Hydrogen-oxygen complex is claimed to be stable even at T > 1000°C in the hydrothermally synthesized ZnO. Therefore, the thermodynamic nature of hydrogen characteristics remains controversial, particularly its role on resident defects. In this letter, in situ temperature dependent solid state 1H magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy is employed to probe the local chemical environments of hydrogen in ZnO nanorods. To best knowledge of ours, this is the first time that the presence of hydrogen, its concentration, and local transport dynamics are directly chemically determined. Moreover, in situ NMR allows a new approach to investigate the absorption and desorption of protons from different sites on the ZnO nanorods, thus study of site-specific proton dynamics in ZnO becomes feasible.

  16. Superconducting vortex pinning with artificially prepared nanostructures

    E-Print Network [OSTI]

    Rosen, Yaniv Jacob

    E. Dubin, Physica C: Superconductivity 369, 21 (2002). R. D.P. G. De Gennes, Superconductivity of Metals and Alloys (W.Schuller, Journal of Superconductivity and Novel Magnetism

  17. Visualization of Intricate Flow Structures for Vortex Breakdown Analysis Xavier Tricoche

    E-Print Network [OSTI]

    Utah, University of

    Visualization of Intricate Flow Structures for Vortex Breakdown Analysis Xavier Tricoche University, synthetic depictions that permit new insight into the structural properties of vortex breakdowns. CR And Modeling-- Simulation Output Analysis J.2 [Physical Sciences and Engineer- ing]: Engineering--. Keywords

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

    E-Print Network [OSTI]

    Yang, Yi

    2012-02-14T23:59:59.000Z

    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...

  19. Vortex in a relativistic perfect isentropic fluid and Nambu Goto dynamics

    E-Print Network [OSTI]

    B. Boisseau

    1999-11-26T23:59:59.000Z

    By a weak deformation of the cylindrical symmetry of the potential vortex in a relativistic perfect isentropic fluid, we study the possible dynamics of the central line of this vortex. In "stiff" material the Nanbu-Goto equations are obtained

  20. Vortex Shedding from Superhydrophobic Cylinders Nangelie Ferrer, Robert Daniello and Jonathan Rothstein

    E-Print Network [OSTI]

    Mountziaris, T. J.

    Vortex Shedding from Superhydrophobic Cylinders Nangelie Ferrer, Robert Daniello and Jonathan Rothstein University of Massachusetts Amherst Abstract Superhydrophobic surfaces are ideal for applications to characterize the vortex shedding phenomenon observed within the wake region of the superhydrophobic cylinder

  1. Observation of the nuclear magnetic octupole moment of $^{173}$Yb from precise measurements of hyperfine structure in the ${^3P}_2$ state

    E-Print Network [OSTI]

    Singh, Alok K; Natarajan, Vasant

    2015-01-01T23:59:59.000Z

    We measure hyperfine structure in the metastable ${^3P}_2$ state of $^{173}$Yb and extract the nuclear magnetic octupole moment. We populate the state using dipole-allowed transitions through the ${^3P}_1$ and ${^3S}_1$ states. We measure frequencies of hyperfine transitions of the ${^3P}_2 \\rightarrow {^3S}_1$ line at 770 nm using a Rb-stabilized ring cavity resonator with a precision of 200 kHz. Second-order corrections due to perturbations from the nearby ${^3P}_1$ and ${^1P}_1$ states are below 30 kHz. We obtain the hyperfine coefficients as: $A=-742.11(2)$ MHz, $B=1339.2(2)$ MHz, which represent two orders-of-magnitude improvement in precision, and $C=0.54(2)$ MHz. From atomic structure calculations, we obtain the nuclear moments: quadrupole $Q=2.46(12)$ b and octupole $\\Omega=-34.4(21)$ b\\,$\\times \\mu_N$.

  2. Wave–vortex interactions in the nonlinear Schrödinger equation

    SciTech Connect (OSTI)

    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

    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.

  3. Vortex Lattice Studies in CeCoIn? with H?c

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Das, P.; White, J. S.; Holmes, A. T.; Gerber, S.; Forgan, E. M.; Bianchi, A. D.; Kenzelmann, M.; Zolliker, M.; Gavilano, J. L.; Bauer, E. D.; Sarrao, J. L.; Petrovic, C.; Eskildsen, M. R.

    2012-02-01T23:59:59.000Z

    We present small angle neutron scattering studies of the vortex lattice (VL) in CeCoIn? with magnetic fields applied parallel (H) to the antinodal [100] and nodal [110] directions. For H II 100], a single VL orientation is observed, while a 90° reorientation transition is found for H II [110]. For both field orientations and VL configurations we find a distorted hexagonal VL with an anisotropy, ?=2.0±0.05. The VL form factor shows strong Pauli paramagnetic effects similar to what have previously been reported for H II [001]. At high fields, above which the upper critical field (Hc2) becomes a first-order transition, an increased disordering of the VL is observed.

  4. Vortex Lattice Studies in CeCoIn? with H?c

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Das, P.; White, J. S.; Holmes, A. T.; Gerber, S.; Forgan, E. M.; Bianchi, A. D.; Kenzelmann, M.; Zolliker, M.; Gavilano, J. L.; Bauer, E. D.; et al

    2012-02-01T23:59:59.000Z

    We present small angle neutron scattering studies of the vortex lattice (VL) in CeCoIn? with magnetic fields applied parallel (H) to the antinodal [100] and nodal [110] directions. For H II 100], a single VL orientation is observed, while a 90° reorientation transition is found for H II [110]. For both field orientations and VL configurations we find a distorted hexagonal VL with an anisotropy, ?=2.0±0.05. The VL form factor shows strong Pauli paramagnetic effects similar to what have previously been reported for H II [001]. At high fields, above which the upper critical field (Hc2) becomes a first-order transition,more »an increased disordering of the VL is observed.« less

  5. JOURNAL DE PHYSIQUE Colloque C6, suppliment au no 8, Tome 39, aotit 1978, page C6-1379 LONG RANGE MAGNETIC ORDER I N THE SUPERCONDUCTING STATE OF HEAVY RARE EARTH

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    MAGNETIC ORDER I N THE SUPERCONDUCTING STATE OF HEAVY RARE EARTH MOLYBDENUM SULFIDES AND THEIR PSEUDOTERNARY COMPOUNDS M. Ishikawa, 0. Fischer and J. Muller De'pmtement de Physique de Za MatiBre Condense Qgalement exposds. Abstract.- Various experimental evidences for long range magnetic order

  6. Vortex Interactions and Barotropic Aspects of Concentric Eyewall Formation HUNG-CHI KUO

    E-Print Network [OSTI]

    Schubert, Wayne H.

    of a tropical cyclone core with nearby weaker vorticity of various spatial scales. This paper considers, separation distance, companion vortex size, and core vortex skirt parameter. A vorticity skirt on the core­6 times as strong as the larger companion vortex. An additional requirement is that the separation

  7. Nonexistence of Lyapunov Functions and the Instability of the von Karman Vortex Streets

    E-Print Network [OSTI]

    Lim, Chjan C.

    Nonexistence of Lyapunov Functions and the Instability of the von Karman Vortex Streets Chjan Lim of the von Karman vortex streets and the existence of a global Lyapunov function at the special aspect ratio the equilibrium Karman streets are unlikely theoretical candidates for observed vortex trails. On the other hand

  8. Experimental and Numerical Investigations on the Asymmetric Wake Vortex Structures around an Oscillating Airfoil

    E-Print Network [OSTI]

    Hu, Hui

    of the reverse von Karman vortex street behind the flapping wing. However, it is challenging to fully understandExperimental and Numerical Investigations on the Asymmetric Wake Vortex Structures around of the vortex pair becomes more apparent, which is considered to be a vital element to form the asymmetric wake

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

    E-Print Network [OSTI]

    Fontelos, Marco

    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

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

    E-Print Network [OSTI]

    Wright, J. Douglas

    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

  11. Quasi-single helicity state by a small positive pulse of toroidal magnetic field in TPE-RX reversed field pinch experiment

    SciTech Connect (OSTI)

    Hirano, Y.; Koguchi, H.; Yambe, K.; Sakakita, H.; Kiyama, S. [National Institute of Advanced Industrial Science and Technology, Tsukuba-shi, Ibaraki 305-8568 (Japan)

    2006-12-15T23:59:59.000Z

    By applying a small positive pulse ({delta}B{sub ta}) in toroidal magnetic field, the quasi-single helicity (QSH) state can be obtained with a controllable and reproducible manner in a reversed-field pinch (RFP) experiment on the large RFP machine, TPE-RX [Y. Yagi et al., Fusion Eng. Des. 45, 421 (1999)]. The QSH state in RFP is one of the states where the improved confinement can be observed, and is important for development toward the pure single helicity (SH) state. In the SH state, the dynamo-action for sustaining the RFP configuration will be driven by a single helical mode and its harmonics, and the anomalous plasma loss can be avoided which is caused by the multi-helicity dynamo action in ordinary RFPs. In the operating condition presented here, the reversal of toroidal magnetic field (B{sub ta}) is maintained at a shallow value ({approx}-1 mT) for a certain period ({approx}20 ms) after the setting up of the RFP configuration and then the positive {delta}B{sub ta} ((less-or-similar sign)5 mT magnitude and {approx}2 ms width) is applied to the B{sub ta}, which is usually negative during the sustaining phase of RFP. Just after applying the pulse, the m/n=1/6 mode (m and n being the poloidal and toroidal Fourier mode numbers, respectively) grows dominantly and the configuration goes into QSH state. This QSH state can be sustained for a long period (up to {approx}45 ms) almost until the end of discharge by applying a delayed reversal of B{sub ta} with appropriate timing and magnitude. The setting up of the QSH states shows a reproducibility of almost 100% with the same timing corresponding to the applied positive pulse. This observation can confirm the interpretation in the former report [Y. Hirano et al., Phys. Plasmas 12, 112501 (2005)], in which it is claimed that the QSH state is obtained when a small positive pulse in toroidal magnetic field spontaneously appears.

  12. Hydrodynamic loads on flexible marine structures due to vortex shedding

    SciTech Connect (OSTI)

    Every, M.J.; King, R.

    1982-12-01T23:59:59.000Z

    This paper makes a comparison of experimental measurements and a recently developed methodology for the prediction of the increase in the steady drag of a cylinder undergoing vortex-induced vibrations. The experimental results were obtained during the development of a means to reduce the flow-induced vibration of a cable-suspended pile of the COGNAC platform installation and agree well with the predictions made in this paper. Next, a brief consideration is made of some of the authors' experience of methods used to reduce vortex-induced vibrations, and hence stress levels. Finally, a reduction method which used an air-blowing manifold is described and results presented.

  13. Magnetic relaxation of superconducting quantum dot: two-dimensional false vacuum decay

    E-Print Network [OSTI]

    D. R. Gulevich; F. V. Kusmartsev

    2006-09-11T23:59:59.000Z

    Quantum tunneling of vortices has been found to be an important novel phenomena for description of low temperature creep in high temperature superconductors (HTSCs). We speculate that quantum tunneling may be also exhibited in mesoscopic superconductors due to vortices trapped by the Bean-Livingston barrier. The London approximation and method of images is used to estimate the shape of the potential well in superconducting HTSC quantum dot. To calculate the escape rate we use the instanton technique. We model the vortex by a quantum particle tunneling from a two-dimensional ground state under magnetic field applied in the transverse direction. The resulting decay rates obtained by the instanton approach and conventional WKB are compared revealing complete coincidence with each other.

  14. Valence-state Model of Strain-dependent Mn L2,3 X-ray Magnetic Circular Dichroism from Ferromagnetic Semiconductors

    SciTech Connect (OSTI)

    van der Laan, G.; Edmonds, K. W.; Arenholz, E.; Farley, N. R. S.; Gallagher, B. L.

    2010-03-30T23:59:59.000Z

    We present a valence-state model to explain the characteristics of a recently observed pre-edge feature in Mn L{sub 3} x-ray magnetic circular dichroism (XMCD) of ferromagnetic (Ga,Mn)As and (Al,Ga,Mn)As thin films. The prepeak XMCD shows a uniaxial anisotropy, contrary to the cubic symmetry of the main structures induced by the crystalline electric field. Reversing the strain in the host lattice reverses the sign of the uniaxial anisotropy. With increasing carrier localization, the prepeak height increases, indicating an increasing 3d character of the hybridized holes. Hence, the feature is ascribed to transitions from the Mn 2p core level to unoccupied p-d hybridized valence states. The characteristics of the prepeak are readily reproduced by the model calculation taking into account the symmetry of the strain-, spin-orbit-, and exchange-split valence states around the zone center.

  15. Eur. .I. Mech. B/Fluids, 17, no 4, 5499560, 1998 Experimental evidencefor a new type of stretched vortex

    E-Print Network [OSTI]

    Wesfreid, José Eduardo

    , concentrated vorticity can appear as a result of instabilities such as the BCnard-Von Karman vortex street vortex P. PETITJEANS `*, J. H. ROBRES a, J. E. WESFREID a, N. KEVLAHAN b ABSTRACT. - Experimental vortex (which is a non-confined stretched vortex model) are observed and analyzed, 0 Elsevier, Paris 1

  16. Vortex phase-jitter in acoustically excited bluff body flames

    E-Print Network [OSTI]

    Lieuwen, Timothy C.

    Vortex phase-jitter in acoustically excited bluff body flames Santosh J. Shanbhogue, Michael disturbances. Phase locked particle image velocimetry was carried out over a range of conditions", manifested as cycle-to-cycle variation in flame and vorticity field at the same excitation phase. Phase

  17. AXISYMMETRIC VORTEX BREAKDOWN IN AN ENCLOSED CYLINDER FLOW.

    E-Print Network [OSTI]

    Lopez, John M.

    into the interior flow from the Ekman boundary layer on the rotating endwall is observed, as is the formation,. The boundary conditions are also defined precisely since the flow is confined in a fixed volume. As Re and and the flow remains oscillatory. This oscillatory behavior is mostly confined to the central vortex region. 2

  18. Modified Black Hole with Polar Jet and Vortex

    E-Print Network [OSTI]

    T. Tmmalm

    2001-12-06T23:59:59.000Z

    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.

  19. LINEAR DISPERSIVE DECAY ESTIMATES FOR VORTEX SHEETS WITH SURFACE TENSION

    E-Print Network [OSTI]

    Spirn, Daniel

    governing irrotational vortex sheets and water waves with surface tension. Using oscillatory integral order, well- posedness theory poses difficulties; however, local-in-time existence for water waves by the kinematic condition in that the interface does not break. This implies the component of the velocity field

  20. Vortex Shedding on Hydrofoils Its dark and lonely down there...

    E-Print Network [OSTI]

    Vortex Shedding on Hydrofoils Its dark and lonely down there... Improving marine vehicle an underwater vehicle moves, it displaces water, genera6ng a unique velocity that it can u6lize rather than fight those flows, saving energy and improving

  1. Vortex stabilized electron beam compressed fusion grade plasma

    SciTech Connect (OSTI)

    Hershcovitch, Ady [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-03-19T23:59:59.000Z

    Most inertial confinement fusion schemes are comprised of highly compressed dense plasmas. Those schemes involve short, extremely high power, short pulses of beams (lasers, particles) applied to lower density plasmas or solid pellets. An alternative approach could be to shoot an intense electron beam through very dense, atmospheric pressure, vortex stabilized plasma.

  2. Inhomogeneous Vortex Patterns in Rotating Bose-Einstein Condensates

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    be homogeneous within the condensate we prove by means of an asymptotic analysis in the strongly interactingInhomogeneous Vortex Patterns in Rotating Bose-Einstein Condensates M. Correggia , N. Rougerieb, France. May 10, 2012 Abstract We consider a 2D rotating Bose gas described by the Gross-Pitaevskii (GP

  3. Inhomogeneous Vortex Patterns in Rotating Bose-Einstein Condensates

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    should be homogeneous within the condensate we prove by means of an asymptotic analysis in the stronglyInhomogeneous Vortex Patterns in Rotating Bose-Einstein Condensates M. Correggia , N. Rougerieb, France. September 19, 2012 Abstract We consider a 2D rotating Bose gas described by the Gross

  4. Spacetime Defects: von Kármán vortex street like configurations

    E-Print Network [OSTI]

    Patricio S. Letelier

    2001-07-05T23:59:59.000Z

    A special arrangement of spinning strings with dislocations similar to a von K\\'arm\\'an vortex street is studied. We numerically solve the geodesic equations for the special case of a test particle moving along twoinfinite rows of pure dislocations and also discuss the case of pure spinning defects.

  5. "Spectral Implementation" for creating a labeled pseudo-pure state and the Bernstein-Vazirani's algorithm in a four-qubit nuclear magnetic resonance quantum processor

    E-Print Network [OSTI]

    Xinhua Peng; Xiwen Zhu; Ximing Fang; Mang Feng; Maili Liu; Kelin Gao

    2004-02-23T23:59:59.000Z

    A quantum circuit is introducted to describe the preparation of a labeled pseudo-pure state by mutiplet-component excitation scheme which has been experimentally implemented on a 4-qubit nuclear magnetic resonance quantum processor. Meanwhile, we theoretically analyze and numerically inverstigate the low-power selective single-pulse implementation of a controlled-rotation gate, which manifests its validity in our experiment. Based on the labeled pseudo-pure state prepared, a 3-qubit Bernstein-Vazirani algorithm has been experimentally demonstrated by spectral implementation. The "answers" of the computations are indentified from the split speak positions in the spectra of the observer spin, which are equivalent to projective measurements required by the algorithms.

  6. Response to “Comment on ‘General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation’” [Phys. Fluids 26, 119101 (2014)

    SciTech Connect (OSTI)

    Van Gorder, Robert A., E-mail: rav@knights.ucf.edu [Department of Mathematics, University of Central Florida, Orlando, Florida 32816-1364 (United States)

    2014-11-15T23:59:59.000Z

    In R. A. Van Gorder, “General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation,” Phys. Fluids 26, 065105 (2014) I discussed properties of generalized vortex filaments exhibiting purely rotational motion under the low-temperature Svistunov model of the local induction approximation. Such solutions are stationary in terms of translational motion. In the Comment [N. Hietala, “Comment on ‘General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation’ [Phys. Fluids 26, 065105 (2014)],” Phys. Fluids 26, 119101 (2014)], the author criticizes my paper for not including translational motion (although it was clearly stated that the filament motion was assumed rotational). As it turns out, if one is interested in studying the geometric structure of solutions (which was the point of my paper), one obtains the needed qualitative results on the structure of such solutions by studying the purely rotational case. Nevertheless, in this Response I shall discuss the vortex filaments that have both rotational and translational motions. I then briefly discuss why one might want to study such generalized rotating filament solutions, in contrast to simple the standard helical or planar examples (which are really special cases). I also discuss how one can study the time evolution of filaments which exhibit more complicated dynamics than pure translation and rotation. Doing this, one can study non-stationary solutions which initially appear purely rotational and gradually display other dynamics as the filaments evolve.

  7. Vortex-line condensation in three dimensions: A physical mechanism for bosonic topological insulators

    E-Print Network [OSTI]

    Peng Ye; Zheng-Cheng Gu

    2014-11-20T23:59:59.000Z

    Bosonic topological insulators (BTI) in three spatial dimensions are symmetry protected topological (SPT) phases with U(1)$\\rtimes$Z$^T_2$ symmetry, where U(1) is boson particle number conservation, and Z$^T_2$ is time-reversal symmetry with $\\mathcal{T}^2=1$. BTI were first proposed based on the group cohomology theory which suggests two distinct root states, each carrying a $\\mathbb{Z}_2$ index. Soon after, surface anomalous topological orders were proposed to identify different root states of BTI, leading to a new BTI root state beyond the group cohomology classification. Nevertheless, it is still unclear what is the universal physical mechanism for BTI phases and what kinds of microscopic Hamiltonians can realize them. In this paper, we answer the first question by proposing a universal physical mechanism via vortex-line condensation in a superfluid, which can potentially be realized in realistic systems, e.g., helium-4 or cold atoms in optical lattices. Using such a simple physical picture, we find three root phases, of which two of them are classified by group cohomology theory while the other is beyond group cohomology classification. The physical picture also leads to a "natural" bulk dynamic topological quantum field theory (TQFT) description for BTI phases and gives rise to a possible physical pathway towards experimental realizations. Finally, we generalize the vortex-line condensation picture to other symmetries and find that in three dimensions, even for a unitary Z$_2$ symmetry, there could be a nontrivial Z$_2$ SPT phase beyond the group cohomology classification.

  8. PHYSICAL REVIEW B 85, 205134 (2012) Synchrotron x-ray spectroscopy studies of valence and magnetic state in europium metal

    E-Print Network [OSTI]

    Schilling, James

    2012-01-01T23:59:59.000Z

    state in europium metal to extreme pressures W. Bi,1,2,3 N. M. Souza-Neto,2,4 D. Haskel,2 G. Fabbris,1

  9. Magnetic Field Clumping in Massive Star-Forming Regions as Determined from Excited-State OH Absorption and Maser Emission

    E-Print Network [OSTI]

    Vincent L. Fish; Mark J. Reid; Karl M. Menten

    2005-01-10T23:59:59.000Z

    We have observed six high-mass star-forming regions in the 2 Pi 3/2, J = 7/2 lines of OH using the GBT in order to investigate whether the magnetic field, and hence the density, measured in absorption differs from that implied by maser Zeeman splitting. We detect absorption in both the 13441 and 13434 MHz main lines in all six sources. Zeeman splitting in the F = 3-3 absorption line in W3(OH) implies a line-of-sight magnetic field strength of 3.0 +/- 0.3 mG. This is significantly less than full magnetic field strengths detected from OH maser Zeeman splitting, suggesting that OH maser regions may be denser than the non-masing OH material by a factor of several. Zeeman splitting is not detected in other sources, but we are able to place upper limits on B_parallel of 1.2 mG in G10.624-0.385 and 2.9 mG in K3-50. These results are consistent with a density enhancement of the masers, but other explanations for the lower magnetic field in absorption compared to maser emission are possible for these two sources. Absorption in one or both of the 13442 and 13433 MHz satellite lines is also seen in four sources. This is the very first detection of the 2 Pi 3/2, J = 7/2 satellite lines. Ratios of satellite-line to main-line absorption suggest enhancement of the satellite lines from local thermodynamic equilibrium values. Masers are seen in the F = 4-4 and 3-3 transitions of W3(OH) and the 4-4 transition of ON 1. A previously undetected 4-4 maser is seen near -44.85 km/s in W3(OH).

  10. Vortex arrays and meso-scale turbulence of self-propelled particles

    E-Print Network [OSTI]

    Robert Grossmann; Pawel Romanczuk; Markus Bär; Lutz Schimansky-Geier

    2014-05-30T23:59:59.000Z

    Inspired by the Turing mechanism for pattern formation, we propose a simple self-propelled particle model with short-ranged alignment and anti-alignment at larger distances. It is able to produce orientationally ordered states, periodic vortex patterns as well as meso-scale turbulence. The latter phase resembles observations in dense bacterial suspensions. The model allows a systematic derivation and analysis of a kinetic theory as well as hydrodynamic equations for density and momentum fields. A phase diagram with regions of such pattern formation as well as spatially homogeneous orientational order and disorder is obtained from a linear stability analysis of these continuum equations. Microscopic Langevin simulations of the self-propelled particle system are in agreement with these findings.

  11. Pressurized water nuclear reactor system with hot leg vortex mitigator

    DOE Patents [OSTI]

    Lau, Louis K. S. (Monroeville, PA)

    1990-01-01T23:59:59.000Z

    A pressurized water nuclear reactor system includes a vortex mitigator in the form of a cylindrical conduit between the hot leg conduit and a first section of residual heat removal conduit, which conduit leads to a pump and a second section of residual heat removal conduit leading back to the reactor pressure vessel. The cylindrical conduit is of such a size that where the hot leg has an inner diameter D.sub.1, the first section has an inner diameter D.sub.2, and the cylindrical conduit or step nozzle has a length L and an inner diameter of D.sub.3 ; D.sub.3 /D.sub.1 is at least 0.55, D.sub.2 is at least 1.9, and L/D.sub.3 is at least 1.44, whereby cavitation of the pump by a vortex formed in the hot leg is prevented.

  12. 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

  13. Vortex topology and the continuum limit of lattice gauge theories

    E-Print Network [OSTI]

    G. Burgio

    2007-10-02T23:59:59.000Z

    We study the stability of Z_2 topological vortex excitations in d+1 dimensional SU(2) Yang-Mills theory on the lattice at T=0. This is found to depend on d and on the coupling considered. We discuss the connection with lattice artifacts causing bulk transitions in the beta_A-beta_F plane and draw some conclusions regarding the continuum limit of the theory.

  14. Reduction of the planar 4-vortex system at zero momentum

    E-Print Network [OSTI]

    Patrick, George

    in the plane the nth vortex has location zn = xn + iyn Ppl (C2 )N . The Hamiltonian and symplectic form- nally on each factor C of Ppl by (ei , a) · z ei z + a. A momentum mapping is Jpl - N n=1 n 1 2 |zn|2]. To calculate the quotient µe : (Jpl )-1 (µe) (Ppl )µe (Jpl )-1 (µe)/SE(2), one may first translate

  15. Vortex energy and 360 Neel wall in thinfilm

    E-Print Network [OSTI]

    Ignat, Radu

    .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 wall 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

  16. High-precision calculations of vortex sheet motion

    SciTech Connect (OSTI)

    Ely, J.S. (Lewis and Clark College, Portland, OR (United States)); Baker, G.R. (Ohio State Univ., Columbus, OH (United States))

    1994-04-01T23:59:59.000Z

    The motion of a vortex sheet undergoing Kelvin-Helmholtz instability is known to be ill-posed, causing deterioration in numerical calculations from the rapid growth of round-off errors. In particular, it is the smallest scales (introduced by round-off) that grow the fastest. Krasny introduced a spectral filter to suppress the growth of round-off errors of the smallest scales. He was then able to detect evidence supporting asymptotic studies that indicate the formation of a curvature singularity in finite time. We use high precision interval arithmetic, coded in C + +, to re-examine the evolution of a vortex sheet from initial conditions used previously by several researchers. Most importantly, our results are free from the influence of round-off errors. We show excellent agreement between results obtained through high precision interval arithmetic and through the use of Krasny's spectral filter. In particular, our results support the formation of a curvature singularity in finite time. After the time of singularity formation, the markers move in peculiar patterns. We rule out any possibility of this motion resulting from round-off errors, but it does depend on the level of resolution. We find no consistent behavior in the motion of the markers as we improve the resolution of the vortex sheet. Also, we find some disagreement between the results obtained through high precision interval arithmetic and through the use of the spectral filter. 29 refs., 5 figs.

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

    SciTech Connect (OSTI)

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

    2012-01-01T23:59:59.000Z

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

  18. Spontaneous vortex phase and pinning in ferromagnetic-superconducting systems

    E-Print Network [OSTI]

    Kayali, Mohammad Amin

    2004-09-30T23:59:59.000Z

    , the ferromagnetic textures considered here are a circular dot of submicrometer size with in-plane magnetization, an elliptical dot magnetized in the direction perpendicular to the superconductor, and a ferromagnetic dot magnetized in the direction normal...

  19. Journal of Magnetism and Magnetic Materials 281 (2004) 272275 Effects of high magnetic field annealing on texture and

    E-Print Network [OSTI]

    Garmestani, Hamid

    Journal of Magnetism and Magnetic Materials 281 (2004) 272­275 Effects of high magnetic field annealing on texture and magnetic properties of FePd D.S. Lia, *, H. Garmestania , Shi-shen Yanb , M China c National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive

  20. Equilibrium intermediate-state patterns in a type-I superconducting slab in an arbitrarily oriented applied magnetic field

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Clem, John; Prozorov, Ruslan; Wijngaarden, Rinke J.

    2013-09-01T23:59:59.000Z

    The equilibrium topology of superconducting and normal domains in flat type-I superconductors is investigated. Important improvements with respect to previous work are that (1) the energy of the external magnetic field, as deformed by the presence of superconducting domains, is calculated in the sameway for three different topologies and (2) calculations are made for arbitrary orientation of the applied field. A phase diagram is presented for the minimum-energy topology as a function of applied field magnitude and angle. For small (large) applied fields, normal (superconducting) tubes are found, while for intermediate fields, parallel domains have a lower energy. The rangemore »of field magnitudes for which the superconducting-tubes structure is favored shrinks when the field is more in-plane oriented.« less

  1. Equilibrium intermediate-state patterns in a type-I superconducting slab in an arbitrarily oriented applied magnetic field

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Clem, John; Prozorov, Ruslan; Wijngaarden, Rinke J.

    2013-09-01T23:59:59.000Z

    The equilibrium topology of superconducting and normal domains in flat type-I superconductors is investigated. Important improvements with respect to previous work are that (1) the energy of the external magnetic field, as deformed by the presence of superconducting domains, is calculated in the sameway for three different topologies and (2) calculations are made for arbitrary orientation of the applied field. A phase diagram is presented for the minimum-energy topology as a function of applied field magnitude and angle. For small (large) applied fields, normal (superconducting) tubes are found, while for intermediate fields, parallel domains have a lower energy. The range of field magnitudes for which the superconducting-tubes structure is favored shrinks when the field is more in-plane oriented.

  2. Donor impurity states and related terahertz range nonlinear optical response in GaN cylindrical quantum wires: Effects of external electric and magnetic fields

    SciTech Connect (OSTI)

    Correa, J. D. [Departamento de Ciencias Básicas, Universidad de Medellín, Medellín (Colombia); Mora-Ramos, M. E., E-mail: memora@uaem.mx [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca, Morelos (Mexico); Duque, C. A. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)

    2014-06-07T23:59:59.000Z

    We report a study on the optical absorption coefficient associated to hydrogenic impurity interstate transitions in zinc-blende GaN quantum wires of cylindrical shape taking into account the effects of externally applied static electric and magnetic fields. The electron states emerge within the effective mass approximation, via the exact diagonalization of the donor-impurity Hamiltonian with parabolic confinement and external field effects. The nonlinear optical absorption is calculated using a recently derived expression for the dielectric susceptibility, obtained via a nonperturbative solution of the density-matrix Bloch equation. Our results show that this treatment eliminates not only the intensity-dependent bleaching effect but also the change in sign of the nonlinear contribution due to the combined effect of asymmetric impurity location and the applied electric field.

  3. Model for dynamic self-assembled magnetic surface structures.

    SciTech Connect (OSTI)

    Belkin, M.; Glatz, A.; Snezhko, A.; Aranson, I. S.; Materials Science Division; Northwestern Univ.

    2010-07-07T23:59:59.000Z

    We propose a first-principles model for the dynamic self-assembly of magnetic structures at a water-air interface reported in earlier experiments. The model is based on the Navier-Stokes equation for liquids in shallow water approximation coupled to Newton equations for interacting magnetic particles suspended at a water-air interface. The model reproduces most of the observed phenomenology, including spontaneous formation of magnetic snakelike structures, generation of large-scale vortex flows, complex ferromagnetic-antiferromagnetic ordering of the snake, and self-propulsion of bead-snake hybrids.

  4. NATIONAL HIGH MAGNETIC FIELD LABORATORY Operated by Florida State University, University of Florida, Los Alamos National Laboratory

    E-Print Network [OSTI]

    Weston, Ken

    cords in use at the Lab. Supported by the U.S. National Science Foundation and the State of Florida #12 cords you purchase. This means that representative samples of the cord have been tested for foreseeable wire) · As a safety feature, extension cords and most appliances have polarized plugs (one blade wider

  5. Localized states in a strong magnetic field: Resonant scattering and the Dicke effect T. V. Shahbazyan* and S. E. Ulloa

    E-Print Network [OSTI]

    Ulloa, Sergio E.

    , Ohio University, Athens, Ohio 45701-2979 Received 2 October 1997 We study the energy spectrum. If the energy levels of localized states are close to the electron energy in the plane, the system exhibits the functional-integral approach,7 and recently to multilayer systems.16 In the works mentioned above, the energy

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

    E-Print Network [OSTI]

    Dahl, Jason (Jason Michael)

    2008-01-01T23:59:59.000Z

    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 ...

  7. NATIONAL HIGH MAGNETIC FIELD LABORATORY REPORTSVOLUME 12 N0. 1 2005

    E-Print Network [OSTI]

    Weston, Ken

    , and Geochemistry 14 MAGNET SCIENCE & TECHNOLOGY Engineering Materials, Instrumentation, and Magnet Technology Magnet Science & Technology 42 7 including Engineering Materials, Instrumentation, and Magnet TechnologyNATIONAL HIGH MAGNETIC FIELD LABORATORY REPORTSVOLUME 12 · N0. 1 · 2005 OPERATED BY: FLORIDA STATE

  8. A model for universal time scale of vortex ring formation Kamran Mohseni

    E-Print Network [OSTI]

    Mohseni, Kamran

    and Applied Science, 104-44, California Institute of Technology, Pasadena, California 91125 Morteza Gharib Graduate Aeronautical Laboratory, California Institute of Technology, Pasadena, California 91125 Received of the fluid out of the cylinder and the approximation of the vortex at the pinch off moment by a vortex

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

    E-Print Network [OSTI]

    Yang, Vigor

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

  10. The geometric phase and the geometrodynamics of relativistic electron vortex beams

    E-Print Network [OSTI]

    Pratul Bandyopadhyay; Banasri Basu; Debashree Chowdhury

    2013-11-28T23:59:59.000Z

    We have studied here the geometrodynamics of relativistic electron vortex beams from the perspective of the geometric phase associated with the scalar electron encircling the vortex line. It is pointed out that the electron vortex beam carrying orbital angular momentum is a natural consequence of the skyrmion model of a fermion. This follows from the quantization procedure of a fermion in the framework of Nelson's stochastic mechanics when a direction vector (vortex line) is introduced to depict the spin degrees of freedom. In this formalism a fermion is depicted as a scalar particle encircling a vortex line. It is here shown that when the Berry phase acquired by the scalar electron encircling the vortex line involves quantized Dirac monopole we have paraxial (non-paraxial) beam when the vortex line is parallel (orthogonal) to the wavefront propagation direction. Non-paraxial beams incorporate spin-orbit interaction. When the vortex line is tilted with respect to the propagation direction the Berry phase involves non-quantized monopole. The temporal variation of the direction of the tilted vortices is studied here taking into account the renormalization group flow of the monopole charge and it is predicted that this gives rise to spin Hall effect.

  11. PHYSICAL REVIEW B 84, 144511 (2011) Rectification of vortex motion in a circular ratchet channel

    E-Print Network [OSTI]

    Plourde, Britton L. T.

    2011-01-01T23:59:59.000Z

    PHYSICAL REVIEW B 84, 144511 (2011) Rectification of vortex motion in a circular ratchet channel N and induces a net vortex flow without any unbiased external drive, i.e., the ratchet effect. We show containing a single weak-pinning circular ratchet channel in a Corbino geometry and observed a substantial

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

    E-Print Network [OSTI]

    Franz, Marcel

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

  13. FABRICATION ET TUDE D'UN MONOCRISTAL DE VORTEX DANS LE NIOBIUM SUPRACONDUCTEUR

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    447 FABRICATION ET ÉTUDE D'UN MONOCRISTAL DE VORTEX DANS LE NIOBIUM SUPRACONDUCTEUR P. THOREL. 2014 Nous étudions expérimentalement par diffraction de neutrons le réseau de vortex dans le niobium ce V-cristal est liée à celle des axes cristallins du niobium, étant donné la forte anisotropie des

  14. GPU accelerated simulations of bluff body flows using vortex particle methods

    E-Print Network [OSTI]

    Cottet, Georges-Henri

    GPU accelerated simulations of bluff body flows using vortex particle methods Diego Rossinelli in press as: D. Rossinelli et al., GPU accelerated simulations of bluff body flows using vortex particle Penalization Bluff body flows a b s t r a c t We present a GPU accelerated solver for simulations of bluff body

  15. Lateral imaging of the superconducting vortex lattice using Doppler-modulated scanning tunneling microscopy

    E-Print Network [OSTI]

    Wei, John Y.T.

    Lateral imaging of the superconducting vortex lattice using Doppler-modulated scanning tunneling on the quasiparticle tunneling spectrum, we have laterally imaged the vortex lattice in superconducting 2H-NbSe2 that circulates along the sample edge. Above the lower critical field, field can penetrate into the superconductor

  16. Zero modes in vortex-fermion system with compact extra space

    E-Print Network [OSTI]

    A. Nakamula; K. Shiraishi

    2014-10-28T23:59:59.000Z

    The existence of fermionic zero modes is shown in the presence of vortex configuration of pure $SU(2)$ gauge field on the manifold $M_4 \\times S^2$. From the perspective of four-dimensional effective theory, these zero modes are almost the same as the Jackiw-Rossi type zero modes of the vortex-fermion system.

  17. Progress in year 2001 1. Observation of Vortex Lattices in Bose-Einstein Condensates

    E-Print Network [OSTI]

    1 Progress in year 2001 1. Observation of Vortex Lattices in Bose-Einstein Condensates Quantized in rotating gaseous Bose-Einstein condensates (BEC) [2, 3]. We have observed the formation of highly-ordered vortex lattices in a rotating Bose- condensed gas [4]. They were produced by rotating the condensate

  18. Elliptical-inertial instability of rotating Karman vortex streets A. Stegnera

    E-Print Network [OSTI]

    Stegner Alexandre

    Elliptical-inertial instability of rotating Karman vortex streets A. Stegnera Laboratoire de. Unlike the classical bidimensional Karman street, these observed vortex streets are affected by the earth Karman streets. A series of experiments were performed to study the wake of a cylinder in a rotating deep

  19. Vortex ratchet effects in films with a periodic array of antidots Clcio C. de Souza Silva,1,

    E-Print Network [OSTI]

    Moshchalkov, Victor V.

    Vortex ratchet effects in films with a periodic array of antidots Clécio C. de Souza Silva,1, * J The vortex ratchet effect has been studied in Al films patterned with square arrays of submicron antidots. We. In addition, the experiments reveal interesting collective phenomena in the vortex ratchet effect. At fields

  20. American Institute of Aeronautics and Astronautics A Numerical Study of Vortex-Dominated Flow around an Oscillating

    E-Print Network [OSTI]

    Hu, Hui

    flapping motion is due to the reverse von Karman vortex street. Recently, Bohl and Koochesfahani1 haveAmerican Institute of Aeronautics and Astronautics 1 A Numerical Study of Vortex-Dominated Flow at the Reynolds (Re) number of 12600. The effects of the reduced frequency and Strouhal number on the wake vortex

  1. Vortex nozzle for segmenting and transporting metal chips from turning operations

    DOE Patents [OSTI]

    Bieg, L.F.

    1993-04-20T23:59:59.000Z

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

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

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ran, S.; Bud'ko, S. L.; Straszheim, W. E.; Soh, J.; Kim, M. G.; Kreyssig, A.; Goldman, A. I.; Canfield, P. C.

    2012-06-01T23:59:59.000Z

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

  3. Control of magnetic, nonmagnetic, and superconducting states in annealed Ca(Fe1–xCox)?As?

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ran, S.; Bud'ko, S. L.; Straszheim, W. E.; Soh, J.; Kim, M. G.; Kreyssig, A.; Goldman, A. I.; Canfield, P. C.

    2012-06-01T23:59:59.000Z

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

  4. Field-dependent critical state of high-Tc superconducting strip simultaneously exposed to transport current and perpendicular magnetic field

    SciTech Connect (OSTI)

    Xue, Cun; He, An; Yong, Huadong; Zhou, Youhe, E-mail: zhouyh@lzu.edu.cn [Key Laboratory of Mechanics on Disaster and Environment in Western China attached to the Ministry of Education of China, and Department of Mechanics and Engineering Sciences, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China)] [Key Laboratory of Mechanics on Disaster and Environment in Western China attached to the Ministry of Education of China, and Department of Mechanics and Engineering Sciences, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China)

    2013-12-15T23:59:59.000Z

    We present an exact analytical approach for arbitrary field-dependent critical state of high-T{sub c} superconducting strip with transport current. The sheet current and flux-density profiles are derived by solving the integral equations, which agree with experiments quite well. For small transport current, the approximate explicit expressions of sheet current, flux-density and penetration depth for the Kim model are derived based on the mean value theorem for integration. We also extend the results to the field-dependent critical state of superconducting strip in the simultaneous presence of applied field and transport current. The sheet current distributions calculated by the Kim model agree with experiments better than that by the Bean model. Moreover, the lines in the I{sub a}-B{sub a} plane for the Kim model are not monotonic, which is quite different from that the Bean model. The results reveal that the maximum transport current in thin superconducting strip will decrease with increasing applied field which vanishes for the Bean model. The results of this paper are useful to calculate ac susceptibility and ac loss.

  5. VOLUME 83, NUMBER 15 P H Y S I C A L R E V I E W L E T T E R S 11 OCTOBER 1999 Large Contributions of Negative-Energy States to Forbidden Magnetic-Dipole Transition

    E-Print Network [OSTI]

    Johnson, Walter R.

    of Negative-Energy States to Forbidden Magnetic-Dipole Transition Amplitudes in Alkali-Metal Atoms I. M, Notre Dame, Indiana 46556 (Received 20 May 1999) The influence of negative-energy states (NES) on forbidden magnetic-dipole ns1 2 2 n 1 1 s1 2 transitions in alkali-metal atoms is investigated. We find

  6. The Relation Between Dry Vortex Merger and Tropical Cyclone Genesis over the Atlantic Ocean

    SciTech Connect (OSTI)

    Chen, Shu-Hua; Liu, Yi-Chin

    2014-10-27T23:59:59.000Z

    A strong, convective African tropical disturbance has a greater chance to develop into a Tropical 23 Depression (TD) if it merges with a shallow, dry vortex (D-vortex) from the north of the African 24 easterly jet (AEJ) after leaving the western coast. Using 11-year reanalysis data we found that the 25 western tip of a vortex strip at northwestern Africa can serve as dry vortices for the D-vortex 26 merger if it shifts southward. Another source of D-vortices is the westward propagating lows 27 along the southern edge of the Saharan air. The D-vortex merger process occurred for 63.5% of 28 tropical cyclones (TCs) or developing systems over the main development region of the Atlantic 29 Ocean, while it occurred for 54% of non-developing systems. TC genesis could be largely 30 controlled by the large-scale environment, but the differences in characteristics of vortices 31 associated with the D-vortex merger between developing and non-developing systems could 32 potentially help determine their destinies; in general, developing systems were dominated by a 33 more intense and moist south vortex, while non-developing systems were dominated by a north 34 vortex which was more intense, drier, and larger in size. Analysis also shows that 74% of intense 35 developing systems were involved with the D-vortex merger process. More attention needs to be 36 paid to the D-vortex merger and the characteristics of those vortices as they can play significant 37 roles or have a strong indication in Atlantic TC genesis.

  7. Line--energy Ginzburg--Landau models: zero--energy states

    E-Print Network [OSTI]

    Otto, Felix

    Line--energy Ginzburg--Landau models: zero--energy states Pierre­Emmanuel Jabin*, email: jabin of vanishing energy. We classify these zero--energy states in the whole space: They are either con­ stant or a vortex. A bounded domain can sustain a zero--energy state only if the domain is a disk and the state

  8. Observation of Dirac Monopoles in a Synthetic Magnetic Field

    E-Print Network [OSTI]

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

    2014-08-13T23:59:59.000Z

    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.

  9. Brookhaven-Built Magnet Will Catch Subatomic Debris

    ScienceCinema (OSTI)

    Peter Wanderer

    2013-07-22T23:59:59.000Z

    Peter Wanderer, head of Brookhaven's Superconducting Magnet Division, describes the magnet that's being built for the Facility for Rare Isotope Beams at Michigan State University

  10. On the Bean critical-state model in superconductivity

    E-Print Network [OSTI]

    Prigozhin, Leonid

    On the Bean critical-state model in superconductivity L. Prigozhin Department of Mathematics and uniqueness of the solution are proved. 1 Introduction The Bean critical-state model [1, 2] provides on the vortex distribution. According to the Bean model, the distribution of vortices in a type

  11. Decay of helical Kelvin waves on a quantum vortex filament

    SciTech Connect (OSTI)

    Van Gorder, Robert A., E-mail: rav@knights.ucf.edu [Department of Mathematics, University of Central Florida, Orlando, Florida 32816-1364 (United States)

    2014-07-15T23:59:59.000Z

    We study the dynamics of helical Kelvin waves moving along a quantum vortex filament driven by a normal fluid flow. We employ the vector form of the quantum local induction approximation (LIA) due to Schwarz. For an isolated filament, this is an adequate approximation to the full Hall-Vinen-Bekarevich-Khalatnikov dynamics. The motion of such Kelvin waves is both translational (along the quantum vortex filament) and rotational (in the plane orthogonal to the reference axis). We first present an exact closed form solution for the motion of these Kelvin waves in the case of a constant amplitude helix. Such solutions exist for a critical wave number and correspond exactly to the Donnelly-Glaberson instability, so perturbations of such solutions either decay to line filaments or blow-up. This leads us to consider helical Kelvin waves which decay to line filaments. Unlike in the case of constant amplitude helical solutions, the dynamics are much more complicated for the decaying helical waves, owing to the fact that the rate of decay of the helical perturbations along the vortex filament is not constant in time. We give an analytical and numerical description of the motion of decaying helical Kelvin waves, from which we are able to ascertain the influence of the physical parameters on the decay, translational motion along the filament, and rotational motion, of these waves (all of which depend nonlinearly on time). One interesting finding is that the helical Kelvin waves do not decay uniformly. Rather, such waves decay slowly for small time scales, and more rapidly for large time scales. The rotational and translational velocity of the Kelvin waves depend strongly on this rate of decay, and we find that the speed of propagation of a helical Kelvin wave along a quantum filament is large for small time while the wave asymptotically slows as it decays. The rotational velocity of such Kelvin waves along the filament will increase over time, asymptotically reaching a finite value. These decaying Kelvin waves correspond to wave number below the critical value for the Donnelly-Glaberson instability, and hence our results on the Schwarz quantum LIA correspond exactly to what one would expect from prior work on the Donnelly-Glaberson instability.

  12. Bipolar pulse field for magnetic refrigeration

    DOE Patents [OSTI]

    Lubell, Martin S. (Oak Ridge, TN)

    1994-01-01T23:59:59.000Z

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

  13. Bipolar pulse field for magnetic refrigeration

    DOE Patents [OSTI]

    Lubell, M.S.

    1994-10-25T23:59:59.000Z

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

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

    SciTech Connect (OSTI)

    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

    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.

  15. Temperature dependent nucleation and annihilation of individual magnetic vortices.

    SciTech Connect (OSTI)

    Mihajlovic, G.; Patrick, M. S.; Pearson, J. E.; Novosad, V.; Bader, S. D.; Field, M.; Sullivan, G. J.; Hoffmann, A.; Teledyne Scientific Co., LLC

    2010-03-15T23:59:59.000Z

    We studied the temperature dependence of the magnetization reversal in individual submicron permalloy disks with micro-Hall and bend-resistance magnetometry. The nucleation field exhibits a nonmonotonic dependence with positive and negative slopes at low and high temperatures, respectively, while the annihilation field monotonically decreases with increasing temperature, but with distinctly different slopes at low and high temperatures. Our analysis suggests that at low temperatures vortex nucleation and annihilation proceeds via thermal activation over an energy barrier, while at high temperatures they are governed by a temperature dependence of the saturation magnetization.

  16. Magnetic reconnection with asymmetry in the outflow direction

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOEThe Bonneville PowerCherries 82981-1cnHigh SchoolIn12electron 9November 6, InaprilU .MagneticMagnetic Vortex

  17. Gas turbine engine combustor can with trapped vortex cavity

    DOE Patents [OSTI]

    Burrus, David Louis; Joshi, Narendra Digamber; Haynes, Joel Meier; Feitelberg, Alan S.

    2005-10-04T23:59:59.000Z

    A gas turbine engine combustor can downstream of a pre-mixer has a pre-mixer flowpath therein and circumferentially spaced apart swirling vanes disposed across the pre-mixer flowpath. A primary fuel injector is positioned for injecting fuel into the pre-mixer flowpath. A combustion chamber surrounded by an annular combustor liner disposed in supply flow communication with the pre-mixer. An annular trapped dual vortex cavity located at an upstream end of the combustor liner is defined between an annular aft wall, an annular forward wall, and a circular radially outer wall formed therebetween. A cavity opening at a radially inner end of the cavity is spaced apart from the radially outer wall. Air injection first holes are disposed through the forward wall and air injection second holes are disposed through the aft wall. Fuel injection holes are disposed through at least one of the forward and aft walls.

  18. Spectral Techniques for Solving PDE Stability Model of Vortex Rope

    E-Print Network [OSTI]

    Bistrian, Diana Alina

    2012-01-01T23:59:59.000Z

    In this paper spectral methods are applied to investigate the hydrodynamic instability of swirling flow with application to Francis hydraulic turbine. Spectral methods imply representing the problem solution as truncated series of smooth global functions. An L2 - projection and the collocation methods are developed assessing both analytically methodology and computational techniques using symbolic and numerical conversions. Remarks concerning the efficiency and the accuracy of each method in this case are presented. The model of the trailing vortex is used to validate the numerical algorithms with existing results in the literature. All the results are compared to existing ones and they prove to agree quite well. The advantages of using this methods in flow control problems are pointed out.

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

    E-Print Network [OSTI]

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

    2012-09-16T23:59:59.000Z

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

  20. Exact moduli space metrics for hyperbolic vortex polygons

    SciTech Connect (OSTI)

    Krusch, S. [School of Mathematics, Statistics and Actuarial Science, University of Kent, Canterbury CT2 7NF (United Kingdom); Speight, J. M. [Department of Pure Mathematics, University of Leeds, Leeds LS2 9JT (United Kingdom)

    2010-02-15T23:59:59.000Z

    Exact metrics on some totally geodesic submanifolds of the moduli space of static hyperbolic N-vortices are derived. These submanifolds, denoted as {sigma}{sub n,m}, are spaces of C{sub n}-invariant vortex configurations with n single vortices at the vertices of a regular polygon and m=N-n coincident vortices at the polygon's center. The geometric properties of {sigma}{sub n,m} are investigated, and it is found that {sigma}{sub n,n-1} is isometric to the hyperbolic plane of curvature -(3{pi}n){sup -1}. The geodesic flow on {sigma}{sub n,m} and a geometrically natural variant of geodesic flow recently proposed by Collie and Tong ['The dynamics of Chern-Simons vortices', Phys. Rev. D Part. Fields Gravit. Cosmol. 78, 065013 (2008);e-print arXiv:hep-th/0805.0602] are analyzed in detail.

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

    E-Print Network [OSTI]

    Fox, Amanda Katherine

    2000-01-01T23:59:59.000Z

    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...

  2. On the vortex parameter estimation using wide band signals in active acoustic system

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    is an important operation in a large number of applications such as turbine monitoring, de- tection of a vortex in a closed hydraulic test loop. The objective of the work is to emphasize the effect

  3. Falling, flapping, flying, swimming,... : high-Re fluid-solid interactions with vortex shedding

    E-Print Network [OSTI]

    Michelin, Sébastien Honoré Roland

    2009-01-01T23:59:59.000Z

    Meckh. , 1, 79–86. Krasny, R. , 1986a: Desingularisation ofJ. Comp. Phys. , 65, 292–313. Krasny, R. , 1986b: A study ofvortex sheet equation (Krasny, 1986a,b). The vortex sheet

  4. Under consideration for publication in J. Fluid Mech. 1 Mixing in a vortex breakdown flow

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    & Kohlman 1971; Hall 1972; Lowson & Riley 1995) where it creates a sudden drop of the lift and an increase the core of the vortex. Artificial tornadoes within a chimney have been proposed as a way of converting

  5. The vortex merger rate in freely decaying, two-dimensional turbulence J. H. LaCascea

    E-Print Network [OSTI]

    LaCasce, Joseph H.

    vortex models in which energy-conserving mergers were allowed. Trizac19 used a molecular dynamics in laboratory experiments in which vortices were generated by electromagnetic excitation in an electrolyte.10

  6. A Model of Compressor Blade Row Interaction with Shock Induced Vortex Shedding

    E-Print Network [OSTI]

    Cincinnati, University of

    A Model of Compressor Blade Row Interaction with Shock Induced Vortex Shedding Mark G. Turner = circulation = trailing edge thickness = shock angle = density I. Introduction ransonic compressor stages AIAA. Research Scientist, Compressor Aerodynamic Research Laboratory, Associate Fellow AIAA

  7. Hierarchical Colloidal Vortex Rings in a Constant Electric Field Yilong Han and David G. Grier

    E-Print Network [OSTI]

    Grier, David

    15 1050 15 (b) (c) (d) (e) packed close- core vortex ring (d) (e)(b) (c) (a) (f) corona t [sec] Rg) tracking its radius of gyration Rg over time. spheres is surrounded by a diffuse circulating corona

  8. Hierarchical Colloidal Vortex Rings in a Constant Electric Field Yilong Han and David G. Grier

    E-Print Network [OSTI]

    Grier, David

    15 10 5 0 15 (b) (c) (d) (e) packed close- core vortex ring (d) (e) (b) (c) (a) (f) corona t [sec] Rg corona that extends outward for tens of micrometers. Although these clusters somewhat resemble

  9. Effect of traveling waves on Vortex-Induced Vibration of long flexible cylinders

    E-Print Network [OSTI]

    Jaiswal, Vivek, Ph. D. Massachusetts Institute of Technology

    2009-01-01T23:59:59.000Z

    Offshore marine risers and pipelines, exposed to ocean currents, are susceptible to Vortex-Induced Vibration (VIV). Accurate prediction of VIV is necessary for estimating the fatigue life as well as for taking corrective ...

  10. Interacting vortex pairs in inviscid and viscous planar flows Thierry Gallay

    E-Print Network [OSTI]

    Gallay, Thierry

    Interacting vortex pairs in inviscid and viscous planar flows Thierry Gallay Universitâ??e de Grenoble I Institut Fourier, UMR CNRS 5582 B.P. 74 F­38402 Saint­Martin­d'Hâ??eres, France Thierry.Gallay

  11. Interacting vortex pairs in inviscid and viscous planar flows Thierry Gallay

    E-Print Network [OSTI]

    Gallay, Thierry

    Interacting vortex pairs in inviscid and viscous planar flows Thierry Gallay Universit´e de Grenoble I Institut Fourier, UMR CNRS 5582 B.P. 74 F-38402 Saint-Martin-d'H`eres, France Thierry.Gallay

  12. Vortex-induced vibration of marine risers : motion and force reconstruction from field and experimental data

    E-Print Network [OSTI]

    Mukundan, Harish

    2008-01-01T23:59:59.000Z

    Vortex-induced vibration (VIV) of long flexible cylindrical structures enduring ocean currents is ubiquitous in the offshore industry. Though significant effort has gone into understanding this complicated fluid-structure ...

  13. Vortex-induced vibration of flexible cylinders in time-varying flows

    E-Print Network [OSTI]

    Resvanis, Themistocles L

    2014-01-01T23:59:59.000Z

    This thesis investigates two aspects of Vortex-Induced Vibrations (VIV) on long flexible cylinders. The work is split into a minor and major part. The minor part addresses the effect of Reynolds number on flexible cylinder ...

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

    E-Print Network [OSTI]

    Farrell, David Emmanuel

    2007-01-01T23:59:59.000Z

    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 ...

  15. Vortex-induced vibrations of a long flexible cylinder in shear flow

    E-Print Network [OSTI]

    Triantafyllou, Michael S.

    We investigate the in-line and cross-flow vortex-induced vibrations of a long cylindrical tensioned beam, with length to diameter ratio L/D = 200, placed within a linearly sheared oncoming flow, using three-dimensional ...

  16. Enhancement of vortex induced forces and motion through surface roughness control

    DOE Patents [OSTI]

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

    2011-11-01T23:59:59.000Z

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

  17. Soft x-ray microscopy - a powerful analytical tool to image magnetism down to fundamental length and times scales

    E-Print Network [OSTI]

    Fischer, Peter

    2008-01-01T23:59:59.000Z

    analytical tool to image magnetism down to fundamentalmicroscopies Research of magnetism in low dimensions has notnanoscience [3]. Solid state magnetism is also a showcase in

  18. Vortex in a weakly relativistic Bose gas at zero temperature and relativistic fluid approximation

    E-Print Network [OSTI]

    B. Boisseau

    2004-09-14T23:59:59.000Z

    The Bogoliubov procedure in quantum field theory is used to describe a relativistic almost ideal Bose gas at zero temperature. Special attention is given to the study of a vortex. The radius of the vortex in the field description is compared to that obtained in the relativistic fluid approximation. The Kelvin waves are studied and, for long wavelengths, the dispersion relation is obtained by an asymptotic matching method and compared with the non relativistic result.

  19. Magnetic properties in graphene-graphane superlattices

    E-Print Network [OSTI]

    Lee, Joo-Hyoung

    The magnetic properties of graphene-graphane superlattices with zigzag interfaces and separately varying widths are investigated by first-principles density functional calculations. It is demonstrated that magnetic states ...

  20. Magnetic domain walls driven by interfacial phenomena

    E-Print Network [OSTI]

    Emori, Satoru

    2014-01-01T23:59:59.000Z

    A domain wall in a ferromagnetic material is a boundary between differently magnetized regions, and its motion provides a convenient scheme to control the magnetization state of the material. Domain walls can be confined ...

  1. $?^{-}$, $?^{* -}$, $?^{* -}$ and $?^{-}$ decuplet baryon magnetic moments

    E-Print Network [OSTI]

    Milton Dean Slaughter

    2011-04-04T23:59:59.000Z

    The properties of the ground state $U$-Spin $={3/2}$ baryon decuplet magnetic moments $\\Delta^{-}$, $\\Xi^{* -}$, $\\Sigma^{* -}$ and $\\Omega^{-}$ and their ground state spin 1/2 cousins $p$, $n$, $\\Lambda$, $\\Sigma^{+}$, $\\Sigma^{0}$, $\\Sigma^{-}$, $\\Xi^{+}$, and $\\Xi^{-}$ have been studied for many years with a modicum of success. The magnetic moments of many are yet to be determined. Of the decuplet baryons, only the magnetic moment of the $\\Omega^{-}$ has been accurately determined. We calculate the magnetic moments of the \\emph{physical} decuplet $U$-Spin $={3/2}$ quartet members without ascribing any specific form to their quark structure or intra-quark interactions.

  2. The internal structure of a vortex in a two-dimensional superfluid with long healing length and its implications

    SciTech Connect (OSTI)

    Klein, Avraham [The Racah Institute of Physics, The Hebrew University of Jerusalem, 91904 (Israel); Aleiner, Igor L., E-mail: aleiner@phys.columbia.edu [Physics Department, Columbia University, New York, NY 10027 (United States); Agam, Oded [The Racah Institute of Physics, The Hebrew University of Jerusalem, 91904 (Israel); Physics Department, Columbia University, New York, NY 10027 (United States)

    2014-07-15T23:59:59.000Z

    We analyze the motion of quantum vortices in a two-dimensional spinless superfluid within Popov’s hydrodynamic description. In the long healing length limit (where a large number of particles are inside the vortex core) the superfluid dynamics is determined by saddle points of Popov’s action, which, in particular, allows for weak solutions of the Gross–Pitaevskii equation. We solve the resulting equations of motion for a vortex moving with respect to the superfluid and find the reconstruction of the vortex core to be a non-analytic function of the force applied on the vortex. This response produces an anomalously large dipole moment of the vortex and, as a result, the spectrum associated with the vortex motion exhibits narrow resonances lying within the phonon part of the spectrum, contrary to traditional view.

  3. Suppressible pinning of Abrikosov vortices : effects of magnetic vortex arrays on thin superconducting films

    E-Print Network [OSTI]

    Smith, Kevin Daniel

    2008-01-01T23:59:59.000Z

    212507 (2002). [10] M.I. Montero, J.J. Akerman, A. Varilci,J.E. Villegas, M.I. Montero, C. -P. Li and I.K. Schuller,Y. Bruynserede, M.I. Montero, I.K. Schuller, Europhys. Lett.

  4. X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengtheningWildfires may contribute more toConsensusX-RayX-Ray Imaging of the

  5. X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengtheningWildfires may contribute more toConsensusX-RayX-Ray Imaging of

  6. X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645U.S. DOE Office of ScienceandMesa del SolStrengtheningWildfires may contribute more toConsensusX-RayX-Ray Imaging ofX-Ray

  7. X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron SpinPrincetonUsingWhat isJoin theanniversaryI 1 0 3 P 0 d dX-Ray Imaging

  8. X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron SpinPrincetonUsingWhat isJoin theanniversaryI 1 0 3 P 0 d dX-Ray

  9. X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron SpinPrincetonUsingWhat isJoin theanniversaryI 1 0 3 P 0 d dX-RayX-Ray

  10. X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron SpinPrincetonUsingWhat isJoin theanniversaryI 1 0 3 P 0 d

  11. X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron SpinPrincetonUsingWhat isJoin theanniversaryI 1 0 3 P 0 dX-Ray Imaging

  12. Magnetic Field Evolution in Superconducting Neutron Stars

    E-Print Network [OSTI]

    Graber, Vanessa; Glampedakis, Kostas; Lander, Samuel K

    2015-01-01T23:59:59.000Z

    The presence of superconducting and superfluid components in the core of mature neutron stars calls for the rethinking of a number of key magnetohydrodynamical notions like resistivity, the induction equation, magnetic energy and flux-freezing. Using a multi-fluid magnetohydrodynamics formalism, we investigate how the magnetic field evolution is modified when neutron star matter is composed of superfluid neutrons, type-II superconducting protons and relativistic electrons. As an application of this framework, we derive an induction equation where the resistive coupling originates from the mutual friction between the electrons and the vortex/fluxtube arrays of the neutron and proton condensates. The resulting induction equation allows the identification of two timescales that are significantly different from those of standard magnetohydrodynamics. The astrophysical implications of these results are briefly discussed.

  13. Dynamics of a relativistic Rankine vortex for a two-constituent superfluid in a weak perturbation of cylindrical symmetry

    E-Print Network [OSTI]

    B. Boisseau

    1999-01-18T23:59:59.000Z

    From a recent study of a stationary cylindrical solution for a relativistic two-constituent superfluid at low temperature limit, we propose to specify this solution under the form of a relativistic generalisation of a Rankine vortex (Potential vortex whose the core has a solid body rotation).Then we establish the dynamics of the central line of this vortex by supposing that the deviation from the cylindrical configuration is weak in the neighbourhood of the core of the vortex. In "stiff" material the Nambu-Goto equations are obtained.

  14. Model for Dynamic Self-Assembled Magnetic Surface Structures

    E-Print Network [OSTI]

    M. Belkin; A. Glatz; A. Snezhko; I. S. Aranson

    2010-02-02T23:59:59.000Z

    We propose a first-principles model for self-assembled magnetic surface structures on the water-air interface reported in earlier experiments \\cite{snezhko2,snezhko4}. The model is based on the Navier-Stokes equation for liquids in shallow water approximation coupled to Newton equations for interacting magnetic particles suspended on the water-air interface. The model reproduces most of the observed phenomenology, including spontaneous formation of magnetic snake-like structures, generation of large-scale vortex flows, complex ferromagnetic-antiferromagnetic ordering of the snake, and self-propulsion of bead-snake hybrids. The model provides valuable insights into self-organization phenomena in a broad range of non-equilibrium magnetic and electrostatic systems with competing interactions.

  15. Pinning induced by inter-domain wall interactions in planar magnetic nanowires

    SciTech Connect (OSTI)

    Hayward, T.J.; Bryan, M.T.; Fry, P.W.; Fundi, P.M.; Gibbs, M.R.J.; Allwood, D.A.; Im, M.-Y.; Fischer, P.

    2009-10-30T23:59:59.000Z

    We have investigated pinning potentials created by inter-domain wall magnetostatic interactions in planar magnetic nanowires. We show that these potentials can take the form of an energy barrier or an energy well depending on the walls' relative monopole moments, and that the applied magnetic fields required to overcome these potentials are significant. Both transverse and vortex wall pairs are investigated and it is found that transverse walls interact more strongly due to dipolar coupling between their magnetization structures. Simple analytical models which allow the effects of inter-domain wall interactions to be estimated are also presented.

  16. Whole-Body Magnetic Resonance Angiography with Additional Steady-State Acquisition of the Infragenicular Arteries in Patients with Peripheral Arterial Disease

    SciTech Connect (OSTI)

    Nielsen, Yousef W., E-mail: yujwni01@heh.regionh.d [University Hospital at Herlev, Department of Radiology (Denmark); Eiberg, Jonas P. [Rigshospitalet, Department of Vascular Surgery (Denmark); Logager, Vibeke B. [University Hospital at Herlev, Department of Radiology (Denmark); Just, Sven [University Hospital at Gentofte, Department of Radiology (Denmark); Schroeder, Torben V. [Rigshospitalet, Department of Vascular Surgery (Denmark); Thomsen, Henrik S. [University Hospital at Herlev, Department of Radiology (Denmark)

    2010-06-15T23:59:59.000Z

    The purpose of this investigation was to determine if addition of infragenicular steady-state (SS) magnetic resonance angiography (MRA) to first-pass imaging improves diagnostic performance compared with first-pass imaging alone in patients with peripheral arterial disease (PAD) undergoing whole-body (WB) MRA. Twenty consecutive patients with PAD referred to digital-subtraction angiography (DSA) underwent WB-MRA. Using a bolus-chase technique, first-pass WB-MRA was performed from the supra-aortic vessels to the ankles. The blood-pool contrast agent gadofosveset trisodium was used at a dose of 0.03 mmol/kg body weight. Ten minutes after injection of the contrast agent, high-resolution (0.7-mm isotropic voxels) SS-MRA of the infragenicular arteries was performed. Using DSA as the 'gold standard,' sensitivities and specificities for detecting significant arterial stenoses ({>=}50% luminal narrowing) with first-pass WB-MRA, SS-MRA, and combined first-pass and SS-MRA were calculated. Kappa statistics were used to determine intermodality agreement between MRA and DSA. Overall sensitivity and specificity for detecting significant arterial stenoses with first-pass WB-MRA was 0.70 (95% confidence interval 0.61 to 0.78) and 0.97 (0.94 to 0.99), respectively. In first-pass WB-MRA, the lowest sensitivity was in the infragenicular region, with a value of 0.42 (0.23 to 0.63). Combined analysis of first-pass WB-MRA and SS-MRA increased sensitivity to 0.81 (0.60 to 0.93) in the infragenicular region, with specificity of 0.94 (0.88 to 0.97). Sensitivity and specificity for detecting significant arterial stenoses with isolated infragenicular SS-MRA was 0.47 (0.27 to 0.69) and 0.86 (0.78 to 0.91), respectively. Intermodality agreement between MRA and DSA in the infragenicular region was moderate for first-pass WB-MRA ({kappa} = 0.49), fair for SS-MRA ({kappa} = 0.31), and good for combined first-pass/SS-MRA ({kappa} = 0.71). Addition of infragenicular SS-MRA to first-pass WB MRA improves diagnostic performance.

  17. Writing magnetic patterns with surface acoustic waves

    SciTech Connect (OSTI)

    Li, Weiyang; Buford, Benjamin; Jander, Albrecht; Dhagat, Pallavi, E-mail: dhagat@eecs.oregonstate.edu [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, Oregon 97331 (United States)

    2014-05-07T23:59:59.000Z

    A novel patterning technique that creates magnetization patterns in a continuous magnetostrictive film with surface acoustic waves is demonstrated. Patterns of 10??m wide stripes of alternating magnetization and a 3??m dot of reversed magnetization are written using standing and focusing acoustic waves, respectively. The magnetization pattern is size-tunable, erasable, and rewritable by changing the magnetic field and acoustic power. This versatility, along with its solid-state implementation (no moving parts) and electronic control, renders it as a promising technique for application in magnetic recording, magnonic signal processing, magnetic particle manipulation, and spatial magneto-optical modulation.

  18. Vortex generation in protoplanetary disks with an embedded giant planet

    E-Print Network [OSTI]

    M. de Val-Borro; P. Artymowicz; G. D'Angelo; A. Peplinski

    2007-06-21T23:59:59.000Z

    Vortices in protoplanetary disks can capture solid particles and form planetary cores within shorter timescales than those involved in the standard core-accretion model. We investigate vortex generation in thin unmagnetized protoplanetary disks with an embedded giant planet with planet to star mass ratio $10^{-4}$ and $10^{-3}$. Two-dimensional hydrodynamical simulations of a protoplanetary disk with a planet are performed using two different numerical methods. The results of the non-linear simulations are compared with a time-resolved modal analysis of the azimuthally averaged surface density profiles using linear perturbation theory. Finite-difference methods implemented in polar coordinates generate vortices moving along the gap created by Neptune-mass to Jupiter-mass planets. The modal analysis shows that unstable modes are generated with growth rate of order $0.3 \\Omega_K$ for azimuthal numbers m=4,5,6, where $\\Omega_K$ is the local Keplerian frequency. Shock-capturing Cartesian-grid codes do not generate very much vorticity around a giant planet in a standard protoplanetary disk. Modal calculations confirm that the obtained radial profiles of density are less susceptible to the growth of linear modes on timescales of several hundreds of orbital periods. Navier-Stokes viscosity of the order $\

  19. Nanolithographically defined magnetic structures and quantum magnetic disk (invited)

    E-Print Network [OSTI]

    - creasing demands for magnetic storage devices with higher density, faster speed, lower power consumption, smaller size, and lower weight than the current state-of-the-art devices. Presently, most magnetic storage. Chou, Peter R. Krauss, and Linshu Kong NanoStructure Laboratory, Department of Electrical Engineering

  20. NMR (nuclear magnetic resonance) imaging for detecting binder/plasticizers in green-state structural ceramics. [SiC, Al/sub 2/O/sub 3/, and Si/sub 3/N/sub 4/

    SciTech Connect (OSTI)

    Ellingson, W.A.; Ackerman, J.L.; Gronemeyer, S.; Garrido, L.

    1987-06-01T23:59:59.000Z

    We have explored both a small-bore (<10 cm) experimental imaging system as well as a state-of-the-art medical imaging system relative to detection of the soft-solid (wax-like) binders used in ceramics. The ability to detect binders was evaluated on a 1.5-T medical MRI imager (Siemens Magnetom) using T/sub 1/-weighted imaging techniques and a 10-cm eye coil standard with the system. The ability to detect binders was also studied with a modified small-bore coil Technicare Facility using special rf and gradient coils. The initial results show that a medical system may not be able to detect binders unless elevated temperatures are used, whereas the experimental small-bore system shows the distribution quite well. In addition, higher magnetic field strength should be better for ceramics, since proton signal strength increases rapidly with the magnetic field strength. 11 refs., 9 figs., 3 tabs.

  1. ELECTRON SPIN POLARIZATION : A NEW TOOL IN PHOTOEMISSION AND MAGNETISM

    E-Print Network [OSTI]

    Boyer, Edmond

    . On disordering, magnetic semiconductors exhibit new states in the gap which are found to be singly occupied

  2. Transitions between turbulent and laminar superfluid vorticity states in the outer core of a neutron star

    E-Print Network [OSTI]

    C. Peralta; A. Melatos; M. Giacobello; A. Ooi

    2006-07-08T23:59:59.000Z

    We investigate the global transition from a turbulent state of superfluid vorticity to a laminar state, and vice versa, in the outer core of a neutron star. By solving numerically the hydrodynamic Hall-Vinen-Bekarevich-Khalatnikov equations for a rotating superfluid in a differentially rotating spherical shell, we find that the meridional counterflow driven by Ekman pumping exceeds the Donnelly-Glaberson threshold throughout most of the outer core, exciting unstable Kelvin waves which disrupt the rectilinear vortex array, creating a vortex tangle. In the turbulent state, the torque exerted on the crust oscillates, and the crust-core coupling is weaker than in the laminar state. This leads to a new scenario for the rotational glitches observed in radio pulsars: a vortex tangle is sustained in the differentially rotating outer core by the meridional counterflow, a sudden spin-up event brings the crust and core into corotation, the vortex tangle relaxes back to a rectilinear vortex array, then the crust spins down electromagnetically until enough meridional counterflow builds up to reform a vortex tangle. The turbulent-laminar transition can occur uniformly or in patches; the associated time-scales are estimated from vortex filament theory. We calculate numerically the global structure of the flow with and without an inviscid superfluid component, for Hall-Vinen and Gorter-Mellink forms of the mutual friction. We also calculate the post-glitch evolution of the angular velocity of the crust and its time derivative, and compare the results with radio pulse timing data, predicting a correlation between glitch activity and Reynolds number.

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

    SciTech Connect (OSTI)

    Griffin, O. M.

    1980-03-14T23:59:59.000Z

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

  4. A Robust Numerical Method for Integration of Point-Vortex Trajectories in Two Dimensions

    E-Print Network [OSTI]

    Spencer A. Smith; Bruce M. Boghosian

    2010-11-19T23:59:59.000Z

    The venerable 2D point-vortex model plays an important role as a simplified version of many disparate physical systems, including superfluids, Bose-Einstein condensates, certain plasma configurations, and inviscid turbulence. This system is also a veritable mathematical playground, touching upon many different disciplines from topology to dynamic systems theory. Point-vortex dynamics are described by a relatively simple system of nonlinear ODEs which can easily be integrated numerically using an appropriate adaptive time stepping method. As the separation between a pair of vortices relative to all other inter-vortex length scales decreases, however, the computational time required diverges. Accuracy is usually the most discouraging casualty when trying to account for such vortex motion, though the varying energy of this ostensibly Hamiltonian system is a potentially more serious problem. We solve these problems by a series of coordinate transformations: We first transform to action-angle coordinates, which, to lowest order, treat the close pair as a single vortex amongst all others with an internal degree of freedom. We next, and most importantly, apply Lie transform perturbation theory to remove the higher-order correction terms in succession. The overall transformation drastically increases the numerical efficiency and ensures that the total energy remains constant to high accuracy.

  5. Numerical study of Kelvin-Helmholtz instability by the point vortex method

    SciTech Connect (OSTI)

    Krasny, R.

    1983-01-01T23:59:59.000Z

    Rosenhead's classical point vortex numerical method for studying the evolution of a vortex sheet from analytic initial data (Kelvin-Helmholtz instability) is examined using the discrete Fourier analysis techniques of Sulem, Sulem and Frisch. One cause for the chaotic motion previously observed in computations using a large number of vortices is that short wavelength perturbations are introduced spuriously by finite precision arithmetic and become amplified by the model's dynamics. Methods for controlling this source of error are given, and the results confirm the formation of a singularity in a finite time which was previously found by Moore and Meiron, Baker and Orszag using different techniques of analysis. A cusp forms in the vortex sheet strength at the critical time, explaining the onset of erratic particle motion in applications of the numerical methods of Van de Vooren and Fink and Soh to this problem. Unlike those methods, the point vortex approximation remains consistent at the critical time and results of a long time calculation are presented. The singularity is interpreted physically as a discontinuity in the strain rate along the vortex sheet and also as the start of roll up on a small scale. The author numerically studies some aspects of the dependence of the solution on the initial condition and finds agreement with Moore's asymptotic relation between the initial amplitude and the critial time.

  6. Magnetic Resonance Facility (Fact Sheet)

    SciTech Connect (OSTI)

    Not Available

    2012-03-01T23:59:59.000Z

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

  7. Understanding magnetic field reversal mechanisms in mesoscopic magnetic multilayer ring structures

    E-Print Network [OSTI]

    Ng, Bryan

    2008-01-01T23:59:59.000Z

    Patterned pseudo spin-valve rings show great promise for device applications due to their non-volatility and variety of stable magnetic states. However, the magnetic reversal of these elements under an applied field is ...

  8. Wake Tracking and the Detection of Vortex Rings by the Canal Lateral Line of Fish Jan-Moritz P. Franosch,1

    E-Print Network [OSTI]

    van Hemmen, J. Leo

    that pass a fish later- ally [19] as well as vortex rings that are part of a von Ka´rma´n vortex street [20 by the lateral-line sensors so as to enable fish to follow a vortex street. DOI: 10.1103/PhysRevLett.103Wake Tracking and the Detection of Vortex Rings by the Canal Lateral Line of Fish Jan-Moritz P

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

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Femtosecond laser fabrication of micro and nano-disks in single layer graphene using vortex Bessel 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 µm were characterized by spatially resolved

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

    E-Print Network [OSTI]

    Andrei, Eva Y.

    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

  11. Bow-wave-like hydraulic jump and horseshoe vortex around an obstacle in a supercritical open channel flow

    E-Print Network [OSTI]

    Boyer, Edmond

    Bow-wave-like hydraulic jump and horseshoe vortex around an obstacle in a supercritical open the obstacle, two main flow structures are observed: i a hydraulic jump in the near-surface region and ii turbulent regime , the detachment length of the hydraulic jump exceeds the one of the horseshoe vortex

  12. Vortex dipoles by PIV method Click here to see the images and the short movies from this lab

    E-Print Network [OSTI]

    deYoung, Brad

    Introduction A vortex dipole is a jet flow with a system of two vortices of opposite sign at its front. Vortex of density stratification. The simplest case of stratification is a two-layer system. A Plexiglas tank a two-layer system without mixing the fluids, one can float a sheet of paper on top of the salt water

  13. Role of the Vortex-Core Energy on the Berezinskii-Kosterlitz-Thouless Transition in Thin Films of NbN

    E-Print Network [OSTI]

    Raychaudhuri, Pratap

    Role of the Vortex-Core Energy on the Berezinskii-Kosterlitz-Thouless Transition in Thin Films-Kosterlitz-Thouless (BKT) transition in thin films of NbN at various film thickness, by probing the effect of vortex played by the vortex-core energy in determining the characteristic signatures of the BKT physics, and we

  14. A model of the lateral line of fish for vortex sensing This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Mohseni, Kamran

    field around a fish's body in the presence of a Karman vortex street. Karman and reverse Karman streets LLTC model could explain how a fish identifies the characteristics of a Karman vortex street shed that the main characteristics of a vortex street including the magnitude of vortices, their translational speed

  15. Reduction of vortex induced forces and motion through surface roughness control

    DOE Patents [OSTI]

    Bernitsas, Michael M; Raghavan, Kamaldev

    2014-04-01T23:59:59.000Z

    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.

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

    DOE Patents [OSTI]

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

    2012-11-20T23:59:59.000Z

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

  17. Random Vortex-Street Model for a Self-Similar Plane Turbulent Jet

    E-Print Network [OSTI]

    Victor L'vov; Anna Pomyalov; Itamar Procaccia; Rama Govindarajan

    2008-03-18T23:59:59.000Z

    We ask what determines the (small) angle of turbulent jets. To answer this question we first construct a deterministic vortex-street model representing the large scale structure in a self-similar plane turbulent jet. Without adjustable parameters the model reproduces the mean velocity profiles and the transverse positions of the large scale structures, including their mean sweeping velocities, in a quantitative agreement with experiments. Nevertheless the exact self similar arrangement of the vortices (or any other deterministic model) necessarily leads to a collapse of the jet angle. The observed (small) angle results from a competition between vortex sweeping tending to strongly collapse the jet and randomness in the vortex structure, with the latter resulting in a weak spreading of the jet.

  18. Shear Banding and Spatiotemporal Oscillations in Vortex Matter in Nanostructured Superconductors

    E-Print Network [OSTI]

    C. Reichhardt; C. J. Olson Reichhardt

    2009-12-16T23:59:59.000Z

    We propose a simple nanostructured pinning array geometry where a rich variety of complex vortex shear banding phenomena can be realized. A single row of pinning sites is removed from a square pinning array. Shear banding effects arise when vortex motion in the pin-free channel nucleates motion of vortices in the surrounding pinned regions, creating discrete steps in the vortex velocity profile away from the channel. Near the global depinning transition, the width of the band of moving vortices undergoes oscillations or fluctuations that can span the entire system. We use simulations to show that these effects should be observable in the transport properties of the system. Similar large oscillations and shear banding effects are known to occur for sheared complex fluids in which different dynamical phases coexist.

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

    DOE Patents [OSTI]

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

    2009-10-20T23:59:59.000Z

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

  20. Fast superconducting magnetic field switch

    DOE Patents [OSTI]

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

    1996-01-01T23:59:59.000Z

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

  1. Estimating dispersion from a tornado vortex and mesocyclone

    SciTech Connect (OSTI)

    Weber, A.H.; Hunter, C.H.

    1996-06-01T23:59:59.000Z

    Atmospheric dispersion modeling is required to ensure that a postulated breach in radionuclide storage containers at the Savannah River Site (SRS) from a tornado strike of Fujita-scale intensity F2 or higher will not result in an unacceptable dose to individuals. Fujita-scale tornado descriptions are included in Appendix A of this report. Dispersion models previously used at SRS for estimating dispersion following a tornado strike were developed by D.W. Pepper in 1975 (DP-1387, Dispersion of Small Particles) and H.R. Haynes and D.W. Taylor in 1983 (DPST-82-982, Estimating Doses from Tornado Winds). Research conducted in 1983 on the formation and evolution of tornadic thunderstorms has lead to a more complete understanding of the tornado vortex and associated persistent updraft and downdraft regions within the parent thunderstorm. To ensure that appropriate, contemporary methods are used for safety analysis, the Pepper model and the Haynes and Taylor model were evaluated with respect to current knowledge of circulations within tornadic thunderstorms. Pepper`s model is complex numerically but contains most of the desired physical parameterizations. Haynes and Taylor`s model is used with the Puff-Plume model (an emergency response model on the Weather INformation and Display System at SRS) and has provisions for radionuclide deposition and rainout. Haynes and Taylor assumed heavy rain following the tornado for a period of ten minutes, followed by a lighter rain for another ten minutes, then no rain for the period when the material is transported to 100 km downwind. However, neither model incorporates the effects of a nearby thunderstorm downdraft.

  2. Formation of multi-solitons and vortex bright solitons in Bose-condensed alkali-metal atoms

    E-Print Network [OSTI]

    Luca Salasnich

    2003-09-02T23:59:59.000Z

    Formation of multi-solitons and vortex bright solitons in Bose-condensed alkali-metal atoms is analyzed by using the nonpolynomial Schordinger equation. A train of bright solitons is obtained from an axially homogeneous Bose-Einstein condensate by a sudden change of the scattering length from repulsive to attractive. We derive an analytical expression for the number of bright solitons generated by using this mechanism. The formula generalizes a previous formula obtained with the 1D Gross-Pitaevskii equation. In the second part we consider vortex bright solitons, namely cigar-shaped bright solitons with a nonzero angular quantum number $k$ along the axial direction. By using a variational approach we determine the shape of vortex bright solitons, showing that the critical number of atoms for the collapse of the vortex soliton increases with a larger $k$. Finally we calculate monopole and quadrupole collective oscillations of these vortex bright solitons.

  3. Numerical study of Kelvin-Helmholtz instability by the point vortex method

    SciTech Connect (OSTI)

    Krasny, R.

    1983-12-01T23:59:59.000Z

    Rosenhead's classical point vortex numerical method for studying the evolution of a vortex sheet from analytic initial data (Kelvin-Helmholtz instability) is examined using the discrete Fourier analysis techniques of Sulem, Sulem and Frisch. One cause for the chaotic motion previously observed in computations using a large number of vortices is that short wavelength perturbations are introduced spuriously by finite precision arithmetic and become amplified by the model's dynamics. Methods for controlling this source of error are given and the results confirm the formation of a singularity in a finite time which was previously found by Moore and Meiron, Baker and Orszag using different techniques of analysis. A cusp forms in the vortex sheet strength at the critical time, explaining the onset of erratic particle motion in applications of the numerical methods of Van de Vooren and Fink and Soh to this problem. Unlike those methods, the point vortex approximation remains consistent at the critical time and we present the results of a long time calculation. The singularity is interpreted physically as a discontinuity in the strain rate along the vortex sheet and also as the start of roll up on a small scale. We numerically study some aspects of the dependence of the solution on the initial condition and find agreement with Moore's asymptotic relation between the initial amplitude and the critical time. For large initial amplitudes, two cusps form in the sheet strength, corresponding to double roll up. We explain why the Poincare recurrenc theorem does not imply that the sheet will eventually unroll. Our results suggest that beyond the critical time, the vortex sheet becomes a spiral with infinite arclength although we have doubts about the approximation's accuracy in that regime. 36 references, 30 figures, 3 tables.

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

    E-Print Network [OSTI]

    Maynard, Ian Kenneth

    1985-01-01T23:59:59.000Z

    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...

  5. Streamline topology and dilute particle dynamics in a Karman vortex street flow

    E-Print Network [OSTI]

    Wu, Z B

    2003-01-01T23:59:59.000Z

    Three types of streamline topology in a Karman vortex street flow are shown under the variation of spatial parameters. For the motion of dilute particles in the K\\'arm\\'an vortex street flow, there exist a route of bifurcation to a chaotic orbit and more attractors in a bifurcation diagram for the proportion of particle density to fluid density. Along with the increase of spatial parameters in the flow filed, the bifurcation process is suspended, as well as more and more attractors emerge. In the motion of dilute particles, a drag term and gravity term dominate and result in the bifurcation phenomenon.

  6. Magnetic investigations

    SciTech Connect (OSTI)

    Bath, G.D.; Jahren, C.E.; Rosenbaum, J.G. [Geological Survey, Denver, CO (USA); Baldwin, M.J. [Fenix and Scisson, Inc., Mercury, NV (USA)

    1983-12-31T23:59:59.000Z

    Air and ground magnetic anomalies in the Climax stock area of the NTS help define the gross configuration of the stock and detailed configuration of magnetized rocks at the Boundary and Tippinip faults that border the stock. Magnetizations of geologic units were evaluated by measurements of magnetic properties of drill core, minimum estimates of magnetizations from ground magnetic anomalies for near surface rocks, and comparisons of measured anomalies with anomalies computed by a three-dimensional forward program. Alluvial deposits and most sedimentary rocks are nonmagnetic, but drill core measurements reveal large and irregular changes in magnetization for some quartzites and marbles. The magnetizations of quartz monzonite and granodiorite near the stock surface are weak, about 0.15 A/m, and increase at a rate of 0.00196 A/m/m to 1.55 A/m, at depths greater than 700 m (2300 ft). The volcanic rocks of the area are weakly magnetized. Aeromagnetic anomalies 850 m (2800 ft) above the stock are explained by a model consisting of five vertical prisms. Prisms 1, 2, and 3 represent the near surface outline of the stock, prism 4 is one of the models developed by Whitehill (1973), and prism 5 is modified from the model developed by Allingham and Zietz (1962). Most of the anomaly comes from unsampled and strongly-magnetized deep sources that could be either granite or metamorphosed sedimentary rocks. 48 refs., 23 figs., 3 tabs.

  7. BARABAN ET AL. VOL. XXX ' NO. XX ' 000000 ' XXXX www.acsnano.org

    E-Print Network [OSTI]

    Cuniberti, Gianaurelio

    magnetic field is applied to induce thermophoretic motion of the objects via heating a magnetic cap vortex state in the cap structure of Janus motors. Realized here magnetically induced thermophoretic

  8. Magnetic cooling at Risoe DTU

    E-Print Network [OSTI]

    Nielsen, K K; Jensen, J B; Bahl, C R H; Pryds, N; Smith, A; Nordentoft, A; Hattel, J

    2009-01-01T23:59:59.000Z

    Magnetic refrigeration at room temperature is of great interest due to a long-term goal of making refrigeration more energy-efficient, less noisy and free of any environmentally hostile materials. A refrigerator utilizing an active magnetic regenerator (AMR) is based on the magnetocaloric effect, which manifests itself as a temperature change in magnetic materials when subjected to a varying magnetic field. In this work we present the current state of magnetic refrigeration research at Risoe DTU with emphasis on the numerical modeling of an existing AMR test machine. A 2D numerical heat-transfer and fluid-flow model that represents the experimental setup is presented. Experimental data of both no-heat load and heat load situations are compared to the model. Moreover, results from the numerical modeling of the permanent magnet design used in the system are presented.

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

    DOE Patents [OSTI]

    Taboada-Serrano, Patricia; Tsouris, Constantino; Contescu, Cristian I; McFarlane, Joanna

    2013-10-08T23:59:59.000Z

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

  10. Magnetic Field Safety Magnetic Field Safety

    E-Print Network [OSTI]

    McQuade, D. Tyler

    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

  11. Strange Magnetism

    E-Print Network [OSTI]

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

    1998-11-09T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Trosper, Jeffrey Randall

    1994-01-01T23:59:59.000Z

    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...

  13. A Lagrangian approach to identifying vortex pinch-off Clara O'Farrell1

    E-Print Network [OSTI]

    Dabiri, John O.

    A Lagrangian approach to identifying vortex pinch-off Clara O'Farrell1 and John O. Dabiri2 1 Control and Dynamical Systems, California Institute of Technology, Pasadena, California 91125, USA 2 Graduate Aeronautical Laboratories and Bioengineering, California Institute of Technology, Pasadena

  14. Crown copyright Met Office Hurricane dynamics: on the role of Vortex Rossby Waves (VRWs).

    E-Print Network [OSTI]

    © Crown copyright Met Office Hurricane dynamics: on the role of Vortex Rossby Waves (VRWs). Gilbert of numerical weather prediction: hurricanes, typhoons and tropical cyclones · Hurricane intensity · Conclusion #12;© Crown copyright Met Office Hurricane Juan, 28 September 2003, Halifax 75°N 110°W 10°E5°N

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

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

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

  16. Observations of wave-generated vortex ripples on the North Carolina continental shelf

    E-Print Network [OSTI]

    Kirby, James T.

    October 2002. [1] Sand ripples with wavelengths between 0.5 and 3 m were observed on the bottom across, 1882; Forel, 1883; Dingler, 1974; Vincent and Osborne, 1993; Gallagher et al., 1998; Traykovski et al ripples'' by Bagnold [1946], exert a much larger drag on the flow than friction on sand grains. Vortex

  17. Simulation of vortex sheet roll-up: chaos, azimuthal waves, ring merger

    E-Print Network [OSTI]

    Krasny, Robert

    Simulation of vortex sheet roll-up: chaos, azimuthal waves, ring merger Robert KRASNY1 , Keith-1109 USA krasny@umich.edu National Center for Atmospheric Research, Climate andGlobal Dynamics Boulder, axisymmetric, and three- dimensional flow Krasny &Nitsche 2001; Lindsay & Krasny 2001. Vor- tex sheet

  18. Complex Langevin simulation of quantum vortex nucleation in the Bose-Einstein condensate

    E-Print Network [OSTI]

    Tomoya Hayata; Arata Yamamoto

    2014-11-19T23:59:59.000Z

    The ab-initio simulation of quantum vortex nucleation in the Bose-Einstein condensate is performed by adopting the complex Langevin techniques. We simulate the two-component boson field theory at a finite chemical potential under rotation. In the superfluid phase, vortices are generated above a critical angular velocity and the circulation is clearly quantized even in the presence of quantum fluctuations.

  19. Forebay Computational Fluid Dynamics Modeling for The Dalles Dam to Support Vortex Suppress Device Studies

    SciTech Connect (OSTI)

    Rakowski, Cynthia L.; Richmond, Marshall C.; Serkowski, John A.

    2006-12-01T23:59:59.000Z

    A computational fluid dynamics (CFD) model was used in an investigation into the suppression of a surface vortex that forms and the south-most spilling bay at The Dalles Project. The CFD work complemented work at the prototype and the reduced-scale physical models. The CFD model was based on a model developed for other work in the forebay but had additional resolution added near the spillway. Vortex suppression devices (VSDs) were to placed between pier noses and/or in the bulkhead slot of the spillway bays. The simulations in this study showed that placing VSD structures or a combination of structures to suppress the vortex would still result in near-surface flows to be entrained in a vortex near the downstream spillwall. These results were supported by physical model and prototype studies. However, there was a consensus of the fish biologists at the physical model that the fish would most likely move north and if the fish went under the VSD it would immediately exit the forebay through the tainter gate and not get trapped between VSDs or the VSDs and the tainter gate if the VSDs were deep enough.

  20. Wavelet analysis of vortex breakdown Jori E. Ruppert-Felsot1

    E-Print Network [OSTI]

    École Normale Supérieure

    Wavelet analysis of vortex breakdown Jori E. Ruppert-Felsot1 , Marie Farge1 , and Philippe the experimentally mea- sured flow field using orthogonal wavelets to observe the time evolution of the bursting. The discrete wavelet transform is used to separate the flow field into a coherent component, capturing

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

    E-Print Network [OSTI]

    Yang, Jianke

    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

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

    E-Print Network [OSTI]

    Dalziel, Stuart

    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

  3. Reduced gravity rankine cycle design and optimization with passive vortex phase separation 

    E-Print Network [OSTI]

    Supak, Kevin Robert

    2009-05-15T23:59:59.000Z

    Interphase Transport Phenomena kW(e) Kilowatts-Electric MVS Microgravity Vortex Separator ORNL Oak Ridge National Laboratory SNAP Systems For Nuclear Auxiliary Power MPRE Medium Power Reactor Experiment RFMD Rotary Fluid Management Device RPM...............................................................................................3 History of Space Rankine Cycle Development .....................................6 ORNL Rankine Cycle Design..............................................................10 Space Rankine Cycle Components...

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

    E-Print Network [OSTI]

    Supak, Kevin Robert

    2008-10-10T23:59:59.000Z

    Interphase Transport Phenomena kW(e) Kilowatts-Electric MVS Microgravity Vortex Separator ORNL Oak Ridge National Laboratory SNAP Systems For Nuclear Auxiliary Power MPRE Medium Power Reactor Experiment RFMD Rotary Fluid Management Device RPM...............................................................................................3 History of Space Rankine Cycle Development .....................................6 ORNL Rankine Cycle Design..............................................................10 Space Rankine Cycle Components...

  5. Origin of Reversed Vortex Ratchet Motion W. Gillijns, A. V. Silhanek, and V. V. Moshchalkov

    E-Print Network [OSTI]

    Moshchalkov, Victor V.

    Origin of Reversed Vortex Ratchet Motion W. Gillijns, A. V. Silhanek, and V. V. Moshchalkov INPAC. This rectified motion of particles, known as a rocked ratchet, is basically the result of the broken spatial that the particles (flux lines) cannot be regarded as independent entities leads to a far richer ratchet motion

  6. Evolution of an initially columnar vortex terminating normal to a no-slip wall

    E-Print Network [OSTI]

    Lopez, John M.

    Èdewadt-type spatially oscillatory boundary layer within the core region and a potential-like vortex boundary layer at large radii. The toroidal structure results from the interaction between these two boundary layers's theo- retical study only applied to the boundary layer formed away from the core, as have most other

  7. BAROCLINIC VORTICITY PRODUCTION IN PROTOPLANETARY DISKS. II. VORTEX GROWTH AND LONGEVITY

    E-Print Network [OSTI]

    Julien, Keith

    BAROCLINIC VORTICITY PRODUCTION IN PROTOPLANETARY DISKS. II. VORTEX GROWTH AND LONGEVITY Mark R -- instabilities -- methods: numerical -- solar system: formation -- turbulence Online material: color figures 1 the surface. Thus, the potential energy of the tilted isopycnals is converted into the kinetic energy

  8. Vortex avalanches with robust statistics observed in superconducting niobium E. Altshuler,1,2

    E-Print Network [OSTI]

    Zeldov, Eli

    Vortex avalanches with robust statistics observed in superconducting niobium E. Altshuler,1,2 T. H topography of superconducting niobium samples as the external field is slowly increased. The avalanche size in Ref. 11, was quite limited, being based on only a few hundred events. Nowak et al.12 studied niobium

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

    E-Print Network [OSTI]

    Hagberg, Aric

    Vortex-Pair Dynamics in Anisotropic Bistable Media: A Kinematic Approach Aric Hagberg1 and Ehud typically evolves into rotating spiral waves. In an anisotropic system, instead of spiral waves, the vortices can form wave fragments that propagate with a constant speed in a given direction determined

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

    E-Print Network [OSTI]

    Dalziel, Stuart

    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

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

    E-Print Network [OSTI]

    Dalziel, Stuart

    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

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

    E-Print Network [OSTI]

    Dalziel, Stuart

    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

  13. Vortex-peak interaction and lattice shape in rotating two-component Bose-Einstein condensates

    E-Print Network [OSTI]

    Wei, Jun-cheng

    Vortex-peak interaction and lattice shape in rotating two-component Bose-Einstein condensates: November 28, 2011) When a two component Bose-Einstein condensate is placed into rotation, a lattice component condensate is set into rotation, topological defects of both order parameters are created, which

  14. Formation and Decay of Vortex Lattices in Bose-Einstein Condensates at Finite Temperatures

    E-Print Network [OSTI]

    Formation and Decay of Vortex Lattices in Bose-Einstein Condensates at Finite Temperatures Gaseous Bose-Einstein condensates (BEC) are a testbed for many-body theory. Recently, rotating condensates was observed non-destructively by monitoring the centrifugal distortions of the rotating condensate

  15. ccsd00003161, Vortex patterns in a fast rotating Bose-Einstein condensate

    E-Print Network [OSTI]

    . Furthermore we restrict our analysis to the case of a two-dimensional gas in the xy plane, assumingccsd­00003161, version 1 ­ 26 Oct 2004 Vortex patterns in a fast rotating Bose-Einstein condensate, France (Dated: October 26, 2004) For a fast rotating condensate in a harmonic trap, we investigate

  16. Spacetime Defects von K\\'arm\\'an vortex street like configurations

    E-Print Network [OSTI]

    Letelier, P S

    2001-01-01T23:59:59.000Z

    A special arrangement of spinning strings with dislocations similar to a von K\\'arm\\'an vortex street is studied. We numerically solve the geodesic equations for the special case of a test particle moving along twoinfinite rows of pure dislocations and also discuss the case of pure spinning defects.

  17. Theory of vortex crystal formation in two-dimensional turbulence* Dezhe Z. Jin

    E-Print Network [OSTI]

    California at San Diego, University of

    Theory of vortex crystal formation in two-dimensional turbulence* Dezhe Z. Jin and Daniel H. E are symmetric arrays of strong vortices within a background of weaker vorticity. This paper presents a theory, a theory is advanced that allows us to predict from the initial conditions the approximate number

  18. Numerical modelling and analysis of a room temperature magnetic

    E-Print Network [OSTI]

    Numerical modelling and analysis of a room temperature magnetic refrigeration system Thomas Frank and analysis of a room temperature magnetic refrigeration system Department: Fuel Cells and Solid State-dimensional mathematical model of an Active Magnetic Regenerator (AMR) system which is used for magnetic refrigeration

  19. active paramagnetic lanthanideiii-chrysin: Topics by E-print...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    state characterized by the condensation of charged gluons and the creation of magnetic flux tubes. In the vortex state the magnetic field outside the flux tubes is equal to the...

  20. Magnetic nanotubes

    DOE Patents [OSTI]

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

    2010-11-16T23:59:59.000Z

    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.

  1. Low dimensional magnetism

    E-Print Network [OSTI]

    Kjall, Jonas Alexander

    2012-01-01T23:59:59.000Z

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

  2. Magnetic hysteresis from the geometrical barrier in type-II superconducting strips

    SciTech Connect (OSTI)

    Benkraouda, M.; Clem, J.R. [Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)] [Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)

    1996-03-01T23:59:59.000Z

    The magnetic hysteresis due to the geometrical barrier in a type-II superconducting strip placed in a perpendicular applied field is examined theoretically. We first consider ideal strips with no bulk pinning and show results for the average flux density as a function of the applied field for both flux entry and exit. The magnetization is found to be nearly inversely proportional to the applied field upon flux entry and to be proportional to the applied field upon flux exit. We also present results showing the time evolution of magnetic-flux and current-density profiles during initial flux entry for samples that are bulk-pinning free and those with pinning characterized by a critical current {ital J}{sub {ital c}}. As predicted theoretically in pinning-free strips, the vortices collect in a dome-shaped magnetic flux profile, within which the current density is zero. A vortex-free region develops near the edges, where a high current density flows. With bulk pinning, the vortices pile up in two symmetric dome-shaped magnetic flux profiles, within which the current density is equal to the critical current density, whereas the regions near the center and the edges of the strip remain vortex-free. {copyright} {ital 1996 The American Physical Society.}

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

    E-Print Network [OSTI]

    Schlegel, Fabrice

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

  4. Platinum dendritic nanoparticles with magnetic behavior

    SciTech Connect (OSTI)

    Li, Wenxian, E-mail: wl240@uowmail.edu.au [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2522 (Australia); Solar Energy Technologies, School of Computing, Engineering, and Mathematics, University of Western Sydney, Penrith NSW 2751 (Australia); Sun, Ziqi; Nevirkovets, Ivan P.; Dou, Shi-Xue [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2522 (Australia); Tian, Dongliang [Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of the Ministry of Education, School of Chemistry and the Environment, Beihang University, Beijing 100191 (China)

    2014-07-21T23:59:59.000Z

    Magnetic nanoparticles have attracted increasing attention for biomedical applications in magnetic resonance imaging, high frequency magnetic field hyperthermia therapies, and magnetic-field-gradient-targeted drug delivery. In this study, three-dimensional (3D) platinum nanostructures with large surface area that features magnetic behavior have been demonstrated. The well-developed 3D nanodendrites consist of plentiful interconnected nano-arms ?4?nm in size. The magnetic behavior of the 3D dendritic Pt nanoparticles is contributed by the localization of surface electrons due to strongly bonded oxygen/Pluronic F127 and the local magnetic moment induced by oxygen vacancies on the neighboring Pt and O atoms. The magnetization of the nanoparticles exhibits a mixed paramagnetic and ferromagnetic state, originating from the core and surface, respectively. The 3D nanodendrite structure is suitable for surface modification and high amounts of drug loading if the transition temperature was enhanced to room temperature properly.

  5. Controlling Magnetism at the Nanoscale

    E-Print Network [OSTI]

    Wong, Jared

    2012-01-01T23:59:59.000Z

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

  6. Direct observation of the topological charge of a terahertz vortex beam generated by a Tsurupica spiral phase plate

    SciTech Connect (OSTI)

    Miyamoto, K., E-mail: k-miyamoto@faculty.chiba-u.jp [Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Suizu, K.; Akiba, T. [Department of Electrical, Electronics and Computer Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino, Chiba 275-0016 (Japan); Omatsu, T. [Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); CREST Japan Science and Technology Agency, Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan)

    2014-06-30T23:59:59.000Z

    A terahertz (THz) spiral phase plate with high transmission (>90% after Fresnel correction) and low dispersion has been developed based on the Tsurupica olefin polymer. Direct observations of the topological charge (both magnitude and sign) of a THz vortex beam are performed by using a THz camera with tilted lens focusing and radial defect introduction. The vortex outputs with a topological charge of ±1 (or ±2) are obtained at a frequency of 2 (or 4) THz.

  7. Nuclear magnetic resonance: Its role as a microscopic probe of the electronic and magnetic properties of High-{Tc} superconductors and related materials

    SciTech Connect (OSTI)

    Suh, Byoung Jin

    1995-12-27T23:59:59.000Z

    NMR experiments are reported for Sr{sub 2}CuO{sub 2}Cl{sub 2}, HgBa{sub 2}CuO{sub 4+d}, YNi{sub 2}B{sub 2}C and YBa{sub 2}Cu{sub 3}O{sub 7}. NMR studies typify three different aspects of microscopic properties of HTSC. In non-superconducting antiferromagnetic (AF) prototype Sr{sub 2}CuO{sub 2}Cl{sub 2}, we used NMR to investigate Cu{sup 2+} correlated spin dynamics and AF phase transition in CuO2 layers. In the superconductors, we used NMR both to investigate the electronic properties of the Fermi-liquid in normal and superconducting states and to investigate flux lattice and flux-line dynamics in the superconducting state in presence of magnetic field. A summary of each study is given: {sup 35}Cl NMR was measured in Sr{sub 2}CuO{sub 2}Cl{sub 2} single crystals with T{sub N}=257K. {sub 35}Cl NMR relaxation rates showed crossover of Cu{sup 2+} spin dynamics from Heisenberg to XY-like correlation at 290 K well above T{sub N}. A field-dependent T{sub N} for H{perpendicular}c was observed and explained by a field-induced Ising-like anisotropy in ab plane. {sup 199}Hg NMR was measured in HgBa{sub 2}CuO{sub 4+d}. Properties of the Fermi-liquid are characterized by a single-spin fluid picture and opening of a spin pseudo-gap at q=0 above {Tc}. Below {Tc}, spin component of Knight shift decreases rapidly in agreement with prediction for d-wave pairing scheme. {sup 11}B and {sup 89}Y NMR/magnetization were measured in YNi{sub 2}B{sub 2}C. Temperature dependence of {sup 11}B Knight shift and of the NSLR gave a normal state which agrees with the Korringa relation, indicating that the AF fluctuations on the Ni sublattice are negligible. Opening of the superconducting gap obeys BCS. A NMR approach to investigate vortex thermal motion in HTSC is presented, based on contribution of thermal flux-lines motion to both T{sub 2}{sup {minus}1} and T{sub 1}{sup {minus}1}. Effects are demonstrated in YBa{sub 2}Cu{sub 3}O{sub 7} and HgBa{sub 2}CuO{sub 4+d}.

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

    SciTech Connect (OSTI)

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

    1995-10-01T23:59:59.000Z

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

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

    SciTech Connect (OSTI)

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

    1995-12-31T23:59:59.000Z

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

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

    SciTech Connect (OSTI)

    Hibbs, R.G.; Acharya, S.; Chen, Y.; Nikitopoulos, D.E.; Myrum, T.A. [Louisiana State Univ., Baton Rouge, LA (United States). Mechanical Engineering Dept.

    1998-07-01T23:59:59.000Z

    The effect of vortex generators on the mass (heat) transfer from the ribbed passage of a two-pass turbine blade coolant channel is investigated with the intent of optimizing the vortex generator geometry so that significant enhancements in mass/heat transfer can be achieved. In the experimental configuration considered, ribs are mounted on two opposite walls; all four walls along each pass are active and have mass transfer from their surfaces but the ribs are nonparticipating. Mass transfer measurements, in the form of Sherwood number ratios, are made along the centerline and in selected interrib modules. Results are presented for Reynolds number in the range of 5000 to 40,000 pitch to rib height ratios of 10.5 and 21, and vortex generator-rib spacing to rib height ratios of 0.55 and 1.5. Centerline and spanwise-averaged Sherwood number ratios are presented along with contours of the Sherwood number ratios. Results indicate that the vortex generators lead to substantial increases in the local mass transfer rates, particularly along the side walls, and modest increases in the average mass transfer rates. The vortex generators have the effect of making the interrib profiles along the ribbed walls more uniform. Along the side walls, vortices that characterize the vortex generator wake are associated with significant mass transfer enhancements. The wake effects and the levels of enhancement decrease somewhat with increasing Reynolds number and decreasing pitch.

  11. General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation

    SciTech Connect (OSTI)

    Van Gorder, Robert A., E-mail: rav@knights.ucf.edu [Department of Mathematics, University of Central Florida, Orlando, Florida 32816-1364 (United States)

    2014-06-15T23:59:59.000Z

    In his study of superfluid turbulence in the low-temperature limit, Svistunov [“Superfluid turbulence in the low-temperature limit,” Phys. Rev. B 52, 3647 (1995)] derived a Hamiltonian equation for the self-induced motion of a vortex filament. Under the local induction approximation (LIA), the Svistunov formulation is equivalent to a nonlinear dispersive partial differential equation. In this paper, we consider a family of rotating vortex filament solutions for the LIA reduction of the Svistunov formulation, which we refer to as the 2D LIA (since it permits a potential formulation in terms of two of the three Cartesian coordinates). This class of solutions holds the well-known Hasimoto-type planar vortex filament [H. Hasimoto, “Motion of a vortex filament and its relation to elastica,” J. Phys. Soc. Jpn. 31, 293 (1971)] as one reduction and helical solutions as another. More generally, we obtain solutions which are periodic in the space variable. A systematic analytical study of the behavior of such solutions is carried out. In the case where vortex filaments have small deviations from the axis of rotation, closed analytical forms of the filament solutions are given. A variety of numerical simulations are provided to demonstrate the wide range of rotating filament behaviors possible. Doing so, we are able to determine a number of vortex filament structures not previously studied. We find that the solution structure progresses from planar to helical, and then to more intricate and complex filament structures, possibly indicating the onset of superfluid turbulence.

  12. Neutrino magnetic moment in a magnetized plasma

    E-Print Network [OSTI]

    N. V. Mikheev; E. N. Narynskaya

    2010-11-08T23:59:59.000Z

    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.

  13. Von K\\'arm\\'an Vortex Street within an Impacting Drop

    E-Print Network [OSTI]

    Thoraval, Marie-Jean; Etoh, Takeharu Goji; Popinet, Stephane; Ray, Pascal; Josserand, Christophe; Zaleski, Stephane; Thoroddsen, Sigurdur

    2012-01-01T23:59:59.000Z

    The splashing of a drop impacting onto a liquid pool produces a range of different sized micro-droplets. At high impact velocities, the most significant source of these droplets is a thin liquid jet emerging at the start of the impact from the neck that connects the drop to the pool. We use ultra-high-speed video imaging in combination with high-resolution numerical simulations to show how the ejecta gives way to irregular splashing. At higher Reynolds number, its base becomes unstable, shedding vortex rings into the liquid from the free surface in an axisymmetric von K\\'arm\\'an vortex street, thus breaking the ejecta sheet as it forms.

  14. Magnetic Phenomena in Holographic Superconductivity with Lifshitz Scaling

    E-Print Network [OSTI]

    Dector, Aldo

    2015-01-01T23:59:59.000Z

    We investigate the effects of Lifshitz dynamical critical exponent z on a family of minimal D=4+1 holographic superconducting models, with a particular focus on magnetic phenomena. We see that it is possible to have a consistent Ginzburg-Landau approach to holographic superconductivity in a Lifshitz background. By following this phenomenological approach we are able to compute a wide array of physical quantities. We also calculate the Ginzburg-Landau parameter for different condensates, and conclude that in systems with higher dynamical critical exponent, vortex formation is more strongly unfavored energetically and exhibit a stronger Type I behavior. Finally, following the perturbative approach proposed by Maeda, Natsuume and Okamura, we calculate the critical magnetic field of our models for different values of z.

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

    SciTech Connect (OSTI)

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

    2012-05-15T23:59:59.000Z

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

  16. Hierarchical Colloidal Vortex Rings in a Constant Electric Field Yilong Han and David G. Grier

    E-Print Network [OSTI]

    Grier, David

    often, the dense ring of 30 25 20 15 10 5 0 15 (b) (c) (d) (e) packed close- core vortex ring (d) (e) (b) (c) (a) (f) corona t [sec] Rg (t) [µm] +V h H 20 µm glass slide cluster electrode R g 20 µm FIG. 1 is surrounded by a di#11;use circulating corona that extends outward for tens of micrometers. Although

  17. Under consideration for publication in J. Fluid Mech. 1 Three-dimensional vortex dynamics in

    E-Print Network [OSTI]

    Pawlak, Geno

    , the boundary layer can become centrifugally unstable (Honji 1981), leading to well-developed G¨ortler vortices dissipation and boundary layer dynamics. It is widely accepted that vortex shedding is a dominant pr in oscillatory flow separation M I G U E L C A N A L S AND G E N O P A W L A K Department of Ocean and Resources

  18. Vortex free energy and deconfinement in center-blind discretizations of Yang-Mills theories

    E-Print Network [OSTI]

    Burgio, G; Kerler, W; Müller-Preussker, M

    2006-01-01T23:59:59.000Z

    Maximal 't Hooft loops are studied in SO(3) lattice gauge theory at finite temperature T. Tunneling barriers among twist sectors causing loss of ergodicity for local update algorithms are overcome through parallel tempering, enabling us to measure the vortex free energy F and to identify a deconfinement transition at some $\\beta_A^{crit}$. The behavior of F below $\\beta_A^{crit}$ shows however striking differences with what is expected from discretizations in the fundamental representation.

  19. Petroglyphs, Lighting, and Magnetism

    E-Print Network [OSTI]

    Walker, Merle F

    2007-01-01T23:59:59.000Z

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

  20. Magnetic structure of Coronal Mass Ejections

    E-Print Network [OSTI]

    Lyutikov, Maxim

    2012-01-01T23:59:59.000Z

    We present several models of the magnetic structure of solar coronal mass ejections (CMEs). First, we model CMEs as expanding force-free magnetic structures. While keeping the internal magnetic field structure of the stationary solutions, expansion leads to complicated internal velocities and rotation, while the field structures remain force-free. Second, expansion of a CME can drive resistive dissipation within the CME changing the ionization states of different ions. We fit in situ measurements of ion charge states to the resistive spheromak solutions. Finally, we consider magnetic field structures of fully confined stable magnetic clouds containing both toroidal and poloidal magnetic fields and having no surface current sheets. Expansion of such clouds may lead to sudden onset of reconnection events.

  1. SOLAR MAGNETIC TRACKING. IV. THE DEATH OF MAGNETIC FEATURES

    SciTech Connect (OSTI)

    Lamb, D. A.; Howard, T. A.; DeForest, C. E. [Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States); Parnell, C. E. [School of Mathematics and Statistics, University of St. Andrews, St. Andrews, KY16 9SS (United Kingdom); Welsch, B. T., E-mail: derek@boulder.swri.edu [Space Sciences Laboratory, University of California-Berkeley, 7 Gauss Way, Berkeley, CA 94720 (United States)

    2013-09-10T23:59:59.000Z

    The removal of magnetic flux from the quiet-Sun photosphere is important for maintaining the statistical steady state of the magnetic field there, for determining the magnetic flux budget of the Sun, and for estimating the rate of energy injected into the upper solar atmosphere. Magnetic feature death is a measurable proxy for the removal of detectable flux, either by cancellation (submerging or rising loops, or reconnection in the photosphere) or by dispersal of flux. We used the SWAMIS feature tracking code to understand how nearly 2 Multiplication-Sign 10{sup 4} magnetic features die in an hour-long sequence of Hinode/SOT/NFI magnetograms of a region of the quiet Sun. Of the feature deaths that remove visible magnetic flux from the photosphere, the vast majority do so by a process that merely disperses the previously detected flux so that it is too small and too weak to be detected, rather than completely eliminating it. The behavior of the ensemble average of these dispersals is not consistent with a model of simple planar diffusion, suggesting that the dispersal is constrained by the evolving photospheric velocity field. We introduce the concept of the partial lifetime of magnetic features, and show that the partial lifetime due to Cancellation of magnetic flux, 22 hr, is three times slower than previous measurements of the flux turnover time. This indicates that prior feature-based estimates of the flux replacement time may be too short, in contrast with the tendency for this quantity to decrease as resolution and instrumentation have improved. This suggests that dispersal of flux to smaller scales is more important for the replacement of magnetic fields in the quiet Sun than observed bipolar cancellation. We conclude that processes on spatial scales smaller than those visible to Hinode dominate the processes of flux emergence and cancellation, and therefore also the quantity of magnetic flux that threads the photosphere.

  2. Managing Coil Epoxy Vacuum Impregnation Systems at the Manufacturing Floor Level To Achieve Ultimate Properties in State-of-the-Art Magnet Assemblies

    SciTech Connect (OSTI)

    J.G. Hubrig; G.H. Biallas

    2005-05-01T23:59:59.000Z

    Liquid epoxy resin impregnation systems remain a state-of-the-art polymer material for vacuum and vacuum/pressure impregnation applications in the manufacture of both advanced and conventional coil winding configurations. Epoxy resins inherent latitude in processing parameters accounts for their continued popularity in engineering applications, but also for the tendency to overlook or misinterpret the requisite processing parameters on the manufacturing floor. Resin system impregnation must be managed in detail in order to achieve device life cycle reliability. This closer look reveals how manufacturing floor level management of material acceptance, handling and storage, pre- and post- impregnation processing and cure can be built into a manufacturing plan to increase manufacturing yield, lower unit cost and ensure optimum life cycle performance of the coil.

  3. Investigation of demagnetization in HTS stacked tapes implemented in electric machines as a result of crossed magnetic field

    E-Print Network [OSTI]

    Baghdadi, M.; Ruiz, H. S.; Fagnard, J. F.; Zhang, M.; Wang, W.; Coombs, T. A.

    2014-11-24T23:59:59.000Z

    .e. 600 seconds, was then employed in order to allow the trapped magnetic field to relax due to thermally activated flux creep. Getting ready for applying the crossed field, the sample is turned 90 degrees, thus, the direction of the magnetic field would... testing flux-line cutting physics”, Supercond. Sci. Technol., vol. 24, no. 6, p. 062002, Mar. 2011. [14] G. P. Mikitik and E. H. Brandt, ”Vortex shaking in rectangular super- conducting platelets”, Phys. Rev. B, vol. 69, no. 13, p. 134521, Apr. 2004. [15...

  4. Magnetic Catalysis vs Magnetic Inhibition

    E-Print Network [OSTI]

    Kenji Fukushima; Yoshimasa Hidaka

    2012-09-06T23:59:59.000Z

    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.

  5. Magnetic Stereoscopy

    E-Print Network [OSTI]

    Thomas Wiegelmann; Bernd Inhester

    2006-12-21T23:59:59.000Z

    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.

  6. Superconducting Magnet Division

    E-Print Network [OSTI]

    Superconducting Magnet Division DOE NP Program Review - July 06 1 Brookhaven Magnet Division - Nuclear Physics Program Support Activities Superconducting Magnet Program RHIC Operations Support Spin Summary Peter Wanderer, DOE review, July 25, 2006 Acting Head, Superconducting Magnet Division #12

  7. Argonne X-rays validate quantum magnetism model | Argonne National...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    National Laboratory and Max Planck Institute for Solid State Research in Stuttgart, Germany have validated a theorized model of quantum magnetism by observing it firsthand in a...

  8. Novel nuclear magnetic resonance techniques for studying biological molecules

    E-Print Network [OSTI]

    Laws, David D.

    2010-01-01T23:59:59.000Z

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

  9. atomic beam magnetic: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of atomic phase space density. A magnetic offset field is applied to prevent optical pumping to untrapped states. Our results demonstrate that by a suitable choice of the...

  10. Argonne National Laboratory Partners with Advanced Magnet Lab...

    Energy Savers [EERE]

    next generation wind turbines and accelerate the deployment of advanced turbines for offshore wind energy in the United States. ANL will work with Magnet Lab, Emerson Electric...

  11. Formation of magnetic discontinuities through viscous relaxation

    SciTech Connect (OSTI)

    Kumar, Sanjay; Bhattacharyya, R. [Udaipur Solar Observatory, Physical Research Laboratory, Dewali, Bari Road, Udaipur-313001 (India); Smolarkiewicz, P. K. [European Centre for Medium-Range Weather Forecasts, Reading RG2 9AX (United Kingdom)

    2014-05-15T23:59:59.000Z

    According to Parker's magnetostatic theorem, tangential discontinuities in magnetic field, or current sheets (CSs), are generally unavoidable in an equilibrium magnetofluid with infinite electrical conductivity and complex magnetic topology. These CSs are due to a failure of a magnetic field in achieving force-balance everywhere and preserving its topology while remaining in a spatially continuous state. A recent work [Kumar, Bhattacharyya, and Smolarkiewicz, Phys. Plasmas 20, 112903 (2013)] demonstrated this CS formation utilizing numerical simulations in terms of the vector magnetic field. The magnetohydrodynamic simulations presented here complement the above work by demonstrating CS formation by employing a novel approach of describing the magnetofluid evolution in terms of magnetic flux surfaces instead of the vector magnetic field. The magnetic flux surfaces being the possible sites on which CSs develop, this approach provides a direct visualization of the CS formation, helpful in understanding the governing dynamics. The simulations confirm development of tangential discontinuities through a favorable contortion of magnetic flux surfaces, as the magnetofluid undergoes a topology-preserving viscous relaxation from an initial non-equilibrium state with twisted magnetic field. A crucial finding of this work is in its demonstration of CS formation at spatial locations away from the magnetic nulls.

  12. Interaction of a monopole vortex with an isolated topographic feature in a three-layer geophysical flow

    E-Print Network [OSTI]

    Evgeny A. Ryzhov; K. V. Koshel

    2012-09-27T23:59:59.000Z

    In the frame of a three-layer quasi-geostrophic analytical model of a $f$-plane geophysical flow, Lagrangian advection being induced by the interaction of a monopole vortex with an isolated topographic feature is addressed. Two different cases when the monopole locates either within the upper or the middle layer are of our interest. In the bottom layer, there is a delta function topographic feature, which generates a closed recirculation region in its vicinity due to the background flow. This recirculation region extends to the middle and upper layers, and it plays the role of a topographic vortex. The interaction between the monopole and the topographic vortex causes complex, including chaotic, advection of fluid particles. We show that the model's parameters, namely, the monopole and topographic vortices' strengths and initial positions, the layers' depths and densities are responsible for the diverse advection patterns. While the patterns are rather complicated, however, one can single out two major processes, which mostly govern fluid particle advection. The first one is the variation in time of the system's phase space structure, so that within the closed region of the topographic vortex, there appear periodically unclosed particle pathways by which the particles leave the topographic vortex. The second one is chaotic advection that arises from the nonstationarity of the monopole-topography interaction.

  13. Vortex Dynamics Models in Flow Control Problems Department of Mathematics and Statistics, McMaster University, Hamilton, Ontario L8S

    E-Print Network [OSTI]

    Protas, Bartosz

    . Following a comprehensive review of earlier approaches, we discuss how methods of modern control and optimization theory can be employed to solve control problems for vortex system. In addition, we also address vortex systems, in the second part of the paper we also introduce a novel approach to the control

  14. Magnetic Reconnection

    SciTech Connect (OSTI)

    Masaaki Yamada, Russell Kulsrud and Hantao Ji

    2009-09-17T23:59:59.000Z

    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.

  15. Patterned Magnetic Nanostructures and Quantized Magnetic Disks

    E-Print Network [OSTI]

    -increasing demands in data storage and to new applications of magnetic devices in the field of sensors. NewPatterned Magnetic Nanostructures and Quantized Magnetic Disks STEPHEN Y. CHOU Invited Paper, opens up new opportunities for engineering innovative magnetic materials and devices, developing ultra

  16. Modeling spin magnetization transport in a spatially varying magnetic field

    E-Print Network [OSTI]

    Rico A. R. Picone; Joseph L. Garbini; John A. Sidles

    2014-08-13T23:59:59.000Z

    We present a framework for modeling the transport of any number of globally conserved quantities in any spatial configuration and apply it to obtain a model of magnetization transport for spin-systems that is valid in new regimes (including high-polarization). The framework allows an entropy function to define a model that explicitly respects the laws of thermodynamics. Three facets of the model are explored. First, it is expressed as nonlinear partial differential equations that are valid for the new regime of high dipole-energy and polarization. Second, the nonlinear model is explored in the limit of low dipole-energy (semi-linear), from which is derived a physical parameter characterizing separative magnetization transport (SMT). It is shown that the necessary and sufficient condition for SMT to occur is that the parameter is spatially inhomogeneous. Third, the high spin-temperature (linear) limit is shown to be equivalent to the model of nuclear spin transport of Genack and Redfield. Differences among the three forms of the model are illustrated by numerical solution with parameters corresponding to a magnetic resonance force microscopy (MRFM) experiment. A family of analytic, steady-state solutions to the nonlinear equation is derived and shown to be the spin-temperature analog of the Langevin paramagnetic equation and Curie's law. Finally, we analyze the separative quality of magnetization transport, and a steady-state solution for the magnetization is shown to be compatible with Fenske's separative mass transport equation.

  17. Origin State Destination State

    Annual Energy Outlook 2013 [U.S. Energy Information Administration (EIA)]

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

  18. Origin State Destination State

    Gasoline and Diesel Fuel Update (EIA)

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

  19. An optimized magnet for magnetic refrigeration

    E-Print Network [OSTI]

    Bjørk, R; Smith, A; Christensen, D V; Pryds, N

    2014-01-01T23:59:59.000Z

    A magnet designed for use in a magnetic refrigeration device is presented. The magnet is designed by applying two general schemes for improving a magnet design to a concentric Halbach cylinder magnet design and dimensioning and segmenting this design in an optimum way followed by the construction of the actual magnet. The final design generates a peak value of 1.24 T, an average flux density of 0.9 T in a volume of 2 L using only 7.3 L of magnet, and has an average low flux density of 0.08 T also in a 2 L volume. The working point of all the permanent magnet blocks in the design is very close to the maximum energy density. The final design is characterized in terms of a performance parameter, and it is shown that it is one of the best performing magnet designs published for magnetic refrigeration.

  20. 516 IEEE TRANSACTIONS ON MAGNETICS, VOL. 43, NO. 2, FEBRUARY 2007 Analysis of Permanent-Magnet Machines Using an

    E-Print Network [OSTI]

    Hofmann, Heath F.

    516 IEEE TRANSACTIONS ON MAGNETICS, VOL. 43, NO. 2, FEBRUARY 2007 Analysis of Permanent-Magnet Hofmann Department of Electrical Engineering, The Pennsylvania State University, University Park, PA 16802 USA We present a magnetostatic continuum formulation for computing the magnetic fields and flux

  1. Ultrasound scattering and the study of vortex correlations in disordered flows

    E-Print Network [OSTI]

    Denis Boyer; Fernando Lund

    1999-12-14T23:59:59.000Z

    In an idealized way, some turbulent flows can be pictured by assemblies of many vortices characterized by a set of particle distribution functions. Ultrasound provide an useful, nonintrusive, tool to study the spatial structure of vorticity in flows. This is analogous to the use of elastic neutron scattering to determine liquid structure. We express the dispersion relation, as well as the scattering cross section, of sound waves propagating in a ``liquid'' of identical vortices as a function of vortex pair correlation functions. In two dimensions, formal analogies with ionic liquids are pointed out.

  2. Geometry and scaling of tangled vortex lines in three-dimensional random wave fields

    E-Print Network [OSTI]

    Alexander J. Taylor; Mark R. Dennis

    2015-01-20T23:59:59.000Z

    The short- and long-scale behaviour of tangled wave vortices (nodal lines) in random three-dimensional wave fields is studied via computer experiment. The zero lines are tracked in numerical simulations of periodic superpositions of three-dimensional complex plane waves. The probability distribution of local geometric quantities such as curvature and torsion are compared to previous analytical and new Monte Carlo results from the isotropic Gaussian random wave model. We further examine the scaling and self-similarity of tangled wave vortex lines individually and in the bulk, drawing comparisons with other physical systems of tangled filaments.

  3. Extraordinary optical transmission and vortex excitation by periodic arrays of Fresnel zone plates

    E-Print Network [OSTI]

    Roszkiewicz, A

    2013-01-01T23:59:59.000Z

    Extraordinary optical transmission and good focusing properties of a two-dimensional scattering structure is presented. The structure is made of Fresnel zone plates periodically arranged along two orthogonal directions. Each plate consists of two ring-shaped waveguides supporting modes that match the symmetry of a circularly polarized incident plane wave. High field concentration at the focal plane is obtained with short transverse and long longitudinal foci diameters. Optical vortex excitation in a paraxial region of the transmitted field is also observed and analysed in terms of cross-polarisation coupling. The structure presented may appear useful in visualization, trapping and precise manipulations of nanoparticles.

  4. Thermomagnetic burn control for magnetic fusion reactor

    DOE Patents [OSTI]

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

    1980-07-01T23:59:59.000Z

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

  5. Thermomagnetic burn control for magnetic fusion reactor

    DOE Patents [OSTI]

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

    1982-01-01T23:59:59.000Z

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

  6. The nonlinear coupling between gyroradius scale turbulence and mesoscale magnetic islands in fusion plasmas

    SciTech Connect (OSTI)

    Hornsby, W. A.; Peeters, A. G.; Snodin, A. P.; Casson, F. J.; Camenen, Y.; Szepesi, G. [Department of Physics, Centre for Fusion, Space, and Astrophysics, University of Warwick, Coventry (United Kingdom); Siccinio, M.; Poli, E. [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstrasse 2, D-85748 Garching bei Muenchen (Germany)

    2010-09-15T23:59:59.000Z

    The interaction between small scale turbulence (of the order of the ion Larmor radius) and mesoscale magnetic islands is investigated within the gyrokinetic framework. Turbulence, driven by background temperature and density gradients, over nonlinear mode coupling, pumps energy into long wavelength modes, and can result in an electrostatic vortex mode that coincides with the magnetic island. The strength of the vortex is strongly enhanced by the modified plasma flow response connected with the change in topology, and the transport it generates can compete with the parallel motion along the perturbed magnetic field. Despite the stabilizing effect of sheared plasma flows in and around the island, the net effect of the island is a degradation of the confinement. When density and temperature gradients inside the island are below the threshold for turbulence generation, turbulent fluctuations still persist through turbulence convection and spreading. The latter mechanisms then generate a finite transport flux and, consequently, a finite pressure gradient in the island. A finite radial temperature gradient inside the island is also shown to persist due to the trapped particles, which do not move along the field around the island. In the low collisionality regime, the finite gradient in the trapped population leads to the generation of a bootstrap current, which reduces the neoclassical drive.

  7. Thermodynamic properties of a magnetically modulated graphene

    E-Print Network [OSTI]

    SK Firoz Islam; Naveen K. Singh; Tarun Kanti Ghosh

    2011-09-12T23:59:59.000Z

    The effect of magnetic modulation on thermodynamic properties of a graphene monolayer in presence of a constant perpendicular magnetic field is reported here. One-dimensional spatial electric or magnetic modulation lifts the degeneracy of the Landau levels and converts into bands and their band width oscillates with magnetic field leading to Weiss-type oscillation in the thermodynamic properties. The effect of magnetic modulation on thermodynamic properties of a graphene sheet is studied and then compared with electrically modulated graphene and magnetically modulated conventional two-dimensional electron gas (2DEG). We observe Weiss-type and de Haas-van Alphen (dHvA) oscillations at low and high magnetic field, respectively. There is a definite phase difference in Weiss-type oscillations in thermodynamic quantities of magnetically modulated graphene in compare to electrically modulated graphene. On the other hand, the phase remains same and amplitude of the oscillation is large when compared with the magnetically modulated 2DEG. Explicit asymptotic expressions of density of states and the Helmholtz free energy are provided to understand the phase and amplitude of the Weiss-type oscillations qualitatively. We also study thermodynamic properties when both electric and magnetic modulations are present. The Weiss-type oscillations still exist when the modulations are out-of-phase.

  8. Magnetization process of a single magnetic ring detected by nonlocal spin valve measurement

    E-Print Network [OSTI]

    Otani, Yoshichika

    Magnetization process of a single magnetic ring detected by nonlocal spin valve measurement T of a 200-nm-wide Permalloy ring using a nonlocal spin-valve measurement technique in a lateral geometry state using lateral spin-valve geometry.13­15 The chirality is found to be easily determined from

  9. Superconducting Magnet Division

    E-Print Network [OSTI]

    Gupta, Ramesh

    Superconducting Magnet Division Permanent Magnet Designs with Large Variations in Field Strength the residual field of the magnetized bricks by concentrating flux lines at the iron pole. Low Field Design Medium Field Design Superconducting Magnet Division Dipole and Quadrupole Magnets for RHIC e

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

    SciTech Connect (OSTI)

    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

    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.

  11. Direct femtosecond laser ablation of copper with an optical vortex beam

    SciTech Connect (OSTI)

    Anoop, K. K.; Rubano, A.; Marrucci, L.; Bruzzese, R.; Amoruso, S., E-mail: amoruso@na.infn.it [Dipartimento di Fisica, Università di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); CNR-SPIN, UOS Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy); Fittipaldi, R.; Vecchione, A. [CNR-SPIN, UOS Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (Italy); Wang, X.; Paparo, D. [CNR-SPIN, UOS Napoli, Complesso Universitario di Monte S. Angelo, Via Cintia, I-80126 Napoli (Italy)

    2014-09-21T23:59:59.000Z

    Laser surface structuring of copper is induced by laser ablation with a femtosecond optical vortex beam generated via spin-to-orbital conversion of the angular momentum of light by using a q-plate. The variation of the produced surface structures is studied as a function of the number of pulses, N, and laser fluence, F. After the first laser pulse (N?=?1), the irradiated surface presents an annular region characterized by a corrugated morphology made by a rather complex network of nanometer-scale ridges, wrinkles, pores, and cavities. Increasing the number of pulses (2??1000) and a deep crater is formed. The nanostructure variation with the laser fluence, F, also evidences an interesting dependence, with a coarsening of the structure morphology as F increases. Our experimental findings demonstrate that direct femtosecond laser ablation with optical vortex beams produces interesting patterns not achievable by the more standard beams with a Gaussian intensity profile. They also suggest that appropriate tuning of the experimental conditions (F, N) can allow generating micro- and/or nano-structured surface for any specific application.

  12. Superconducting magnet

    DOE Patents [OSTI]

    Satti, John A. (Naperville, IL)

    1980-01-01T23:59:59.000Z

    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.

  13. Intrinsic subpicosecond magnetization reversal driven by femtosecond laser pulses in GdFeCo amorphous films

    SciTech Connect (OSTI)

    Li, Shufa; Gao, Ruixin; Cheng, Chuyuan; Yan, Yong; Lai, Tianshu, E-mail: stslts@mail.sysu.edu.cn [State-Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, Guangdong 510275 (China)] [State-Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, Guangdong 510275 (China)

    2013-12-09T23:59:59.000Z

    Ultrafast magnetization dynamics in GdFeCo films triggered by femtosecond laser pulses with and without an external field applied is studied experimentally for different excitation fluence. It is found that subpicosecond magnetization reversal occurs simultaneously in the ultrafast dynamics of both saturation and remnant magnetization states and almost identical within 13 ps, whereas relatively slow magnetization reversal across compensation point appears only in the dynamics of saturation magnetization state. It shows the subpicosecond magnetization reversal is external field independent, and originates from intrinsic magnetic evolution in ferrimagnetic system. The intrinsic subpicosecond reversal is qualitatively explained by linear reversal.

  14. Nanostructured magnetic materials

    E-Print Network [OSTI]

    Chan, Keith T.

    2011-01-01T23:59:59.000Z

    Magnetism and Magnetic Materials Conference, Atlanta, GA (Nanostructured Magnetic Materials by Keith T. Chan Doctor ofinduced by a Si-based material occurs at a Si/Ni interface

  15. Interface Magnetism in Multiferroics

    E-Print Network [OSTI]

    He, Qing

    2011-01-01T23:59:59.000Z

    1.2.1 Magnetism . . . . . . . . . . . . . . . . . . . 1.2.2domain walls . . . . . 3 Magnetism of domain walls in BiFeOof electrical control of magnetism in mixed phase BiFeO 3

  16. NATIONAL HIGH MAGNETIC FIELD LABORATORY REPORTSVOLUME 11 N0.1 2004

    E-Print Network [OSTI]

    Weston, Ken

    NATIONAL HIGH MAGNETIC FIELD LABORATORY REPORTSVOLUME 11 · N0.1 · 2004 OPERATED BY: FLORIDA STATE R E V I E W BIOLOGY BIOCHEMISTRY CHEMISTRY CRYOGENICS ENGINEERING MATERIALS GEOCHEMISTRY INSTRUMENTATION KONDO/HEAVY FERMION SYSTEMS MAGNET TECHNOLOGY MAGNETIC RESONANCE TECHNIQUES MAGNETISMAND MAGNETIC

  17. Simulation of a tunable optically pumped terahertz intersubband laser with diluted magnetic semiconductors

    E-Print Network [OSTI]

    Technische Universiteit Delft

    quantum well with a Zn1-xMnxSe diluted magnetic semiconductor barrier is presented. Giant Zeeman splitting in diluted magnetic semiconductors leads to splitting of electronic states, which in turn leads to tunability. INTRODUCTION Diluted magnetic semiconductors DMSs are semicon- ductor alloys partly composed of magnetic

  18. Magnetization measurements of uranium dioxide single crystals (P08358-E002-PF)

    SciTech Connect (OSTI)

    K. Gofryk; V. Zapf; M. Jaime

    2014-12-01T23:59:59.000Z

    Conclusions Our preliminary magnetic susceptibility measurements of UO2 point to complex nature of the magnetic ordering in this material, consistent with the proposed non-collinear 3-k magnetic structure. Further extensive magnetic studies are planned to address the puzzling behavior of UO2 in both antiferromagnetic and paramagnetic states.

  19. Asymmetric neutrino propagation in newly born magnetized strange stars: GRB and kicks

    E-Print Network [OSTI]

    J. Berdermann; D. Blaschke; H. Grigorian; D. N. Voskresensky

    2006-01-21T23:59:59.000Z

    We consider the early cooling evolution of strongly magnetized strange stars in a CFL phase with high gap Delta > 100 MeV. We demonstrate how this model may explain main features of the gamma-ray burst phenomena and also yield a strong star kick. The mechanism is based on beaming of neutrino emission along the magnetic vortex lines. We show that for sufficiently high initial temperatures T_0 ~ 30 - 60 MeV and surface magnetic fields B_s ~ 10^{15} - 10^{17} G, the energy release within the narrow beam is up to 10^{52} erg with a magnetic field dependent time scale between 10^{-2} s (for a smaller magnetic field) to 10 s. The above mechanism together with the parity violation of the neutrino-producing weak interaction processes in a magnetic field allow for the strange star kick. The higher the magnetic field the larger is the stars kick velocity. These velocities may cover the same range as observed pulsar kick velocities.

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

    E-Print Network [OSTI]

    Dabiri, John O.

    Graduate Aeronautical Laboratories and Bioengineering, California Institute of Technology, Pasadena velocity fixed. It turned out that the pinch-off was always observed to occur at a stroke ratio L time scale for the pinch-off process formation number was tested by generating vortex rings

  1. http://rcc.its.psu.edu/hpc Optimization of a Vortex Finder in a Cyclone Separator using

    E-Print Network [OSTI]

    Bjørnstad, Ottar Nordal

    http://rcc.its.psu.edu/hpc Optimization of a Vortex Finder in a Cyclone Separator using Particle of fluidized bed power plants is the cyclone separator. The cyclone separator is used to remove smaller particles, those not large enough for heat transfer, and retain large particles. The cyclone separator

  2. ccsd-00003161,version1-26Oct2004 Vortex patterns in a fast rotating Bose-Einstein condensate

    E-Print Network [OSTI]

    of the rotating gas increases and tends to infinity, and the number of vortices in the condensate diverges [5, 6. Furthermore we restrict our analysis to the case of a two- dimensional gas in the xy plane, assumingccsd-00003161,version1-26Oct2004 Vortex patterns in a fast rotating Bose-Einstein condensate

  3. A model for the symmetry breaking of the reverse Benard-von Karman vortex street produced by a flapping foil

    E-Print Network [OSTI]

    Godoy-Diana, Ramiro; Aider, Jean-Luc; Wesfreid, José Eduardo

    2008-01-01T23:59:59.000Z

    The vortex streets produced by a flapping foil of span-to-chord aspect ratio of 4:1 are studied in a hydrodynamic tunnel experiment. In particular, the mechanisms giving rise to the symmetry breaking of the reverse B\\'enard-von K\\'arm\\'an vortex street that characterizes fish-like swimming and forward flapping flight are examined. Two-dimensional particle image velocimetry measurements in the mid-plane perpendicular to the span axis of the foil are used to characterize the different flow regimes. The deflection angle of the mean jet flow with respect to the horizontal observed in the average velocity field is used as a measure of the asymmetry of the vortex street. Time series of the vorticity field are used to calculate the advection velocity of the vortices with respect to the free-stream, defined as the phase velocity $U_{phase}$, as well as the circulation $\\Gamma$ of each vortex and the spacing $\\xi$ between consecutive vortices in the near wake. The observation that the symmetry breaking results from th...

  4. Thermoelectric Conductivities at Finite Magnetic Field and the Nernst Effect

    E-Print Network [OSTI]

    Keun-Young Kim; Kyung Kiu Kim; Yunseok Seo; Sang-Jin Sin

    2015-03-17T23:59:59.000Z

    We study electric, thermoelectric, and thermal conductivities of a strongly correlated system in the presence of magnetic field by gauge/gravity duality. We consider a general class of Einstein-Maxwell-Dilaton theory with axion fields imposing momentum relaxation. Analytic general formulas for DC conductivities and the Nernst signal are derived in terms of the black hole horizon data. For an explicit model study we analyse in detail the dyonic black hole modified by momentum relaxation. In this model, the Nernst signal shows a typical vortex-liquid effect when momentum relaxation effect is comparable to chemical potential. We compute all AC electric, thermoelectric, and thermal conductivities by numerical analysis and confirms that their zero frequency limits precisely reproduce our analytic formulas, which is a non-trivial consistency check of our methods. We discuss the momentum relaxation effect on conductivities including cyclotron resonance poles.

  5. Thermoelectric Conductivities at Finite Magnetic Field and the Nernst Effect

    E-Print Network [OSTI]

    Kim, Keun-Young; Seo, Yunseok; Sin, Sang-Jin

    2015-01-01T23:59:59.000Z

    We study electric, thermoelectric, and thermal conductivities of a strongly correlated system in the presence of magnetic field by gauge/gravity duality. We consider a general class of Einstein-Maxwell-Dilaton theory with axion fields imposing momentum relaxation. Analytic general formulas for DC conductivities and the Nernst signal are derived in terms of the black hole horizon data. For an explicit model study we analyse in detail the Dyonic black hole modified by momentum relaxation effect. In this model, the Nernst signal shows a typical vortex-liquid effect when momentum relaxation effect is comparable to chemical potential. We compute all AC electric, thermal, and thermal conductivities by numerical analysis and confirms that their zero frequency limits precisely reproduce our analytic formulas, which is a non-trivial consistency check of our methods. We discuss the momentum relaxation effect on conductivities including cyclotron frequencies.

  6. Laced permanent magnet quadrupole drift tube magnets

    SciTech Connect (OSTI)

    Feinberg, B.; Behrsing, G.U.; Halbach, K.; Marks, J.S.; Morrison, M.E.; Nelson, D.H.

    1989-03-01T23:59:59.000Z

    Twenty-three laced permanent magnet quadrupole drift tube magnets have been constructed, tested, and installed in the SuperHILAC heavy ion linear accelerator at LBL, marking the first accelerator use of this new type of quadrupole. The magnets consist of conventional tape-wound quadrupole electromagnets, using iron pole-pieces, with permanent magnet material (samarium cobalt) inserted between the poles to reduce the effects of saturation. The iron is preloaded with magnetic flux generated by the permanent magnet material, resulting in an asymmetrical saturation curve. Since the polarity of the individual quadrupole magnets in a drift tube linac is never reversed, we can take advantage of this asymmetrical saturation to provide about 20% greater focusing strength than is available with conventional quadrupoles, while replacing the vanadium permendur poletips with iron poletips. Comparisons between these magnets and conventional tape-wound quadrupoles will be presented. 3 refs., 5 figs.

  7. SUPERCONDUCTING MAGNETIC ENERGY STORAGE

    E-Print Network [OSTI]

    Hassenzahl, W.

    2011-01-01T23:59:59.000Z

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

  8. SUPERCONDUCTING MAGNETIC ENERGY STORAGE

    E-Print Network [OSTI]

    Hassenzahl, W.

    2011-01-01T23:59:59.000Z

    Design of the BPA Superconducting 30-MJ Energy Storagefor a Utility Scale Superconducting Magnetic Energy Storagefor a Lnrge Scale Superconducting Magnetic Energy Storage

  9. Controlling interactions between highly-magnetic atoms with Feshbach resonances

    E-Print Network [OSTI]

    Svetlana Kotochigova

    2014-10-14T23:59:59.000Z

    This paper reviews current experimental and theoretical progress in the study of dipolar quantum gases of ground and meta-stable atoms with a large magnetic moment. We emphasize the anisotropic nature of Feshbach resonances due to coupling to fast-rotating resonant molecular states in ultracold s-wave collisions between magnetic atoms in external magnetic fields. The dramatic differences in the distribution of resonances of magnetic $^7$S$_3$ chromium and magnetic lanthanide atoms with a submerged 4f shell and non-zero electron angular momentum is analyzed. We focus on Dysprosium and Erbium as important experimental advances have been recently made to cool and create quantum-degenerate gases for these atoms. Finally, we describe progress in locating resonances in collisions of meta-stable magnetic atoms in electronic P states with ground-state atoms, where an interplay between collisional anisotropies and spin-orbit coupling exists.

  10. Magnetization plateaus of dipolar spin ice on kagome lattice

    SciTech Connect (OSTI)

    Xie, Y. L.; Wang, Y. L.; Yan, Z. B.; Liu, J.-M., E-mail: liujm@nju.edu.cn [Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2014-05-07T23:59:59.000Z

    Unlike spin ice on pyrochlore lattice, the spin ice structure on kagome lattice retains net magnetic charge, indicating non-negligible dipolar interaction in modulating the spin ice states. While it is predicted that the dipolar spin ice on kagome lattice exhibits a ground state with magnetic charge order and ?3?×??3 spin order, our work focuses on the magnetization plateau of this system. By employing the Wang-Landau algorithm, it is revealed that the lattice exhibits the fantastic three-step magnetization in response to magnetic field h along the [10] and [01] directions, respectively. For the h//[1 0] case, an additional ?3/6M{sub s} step, where M{sub s} is the saturated magnetization, is observed in a specific temperature range, corresponding to a new state with charge order and short-range spin order.

  11. Magnetic monopole field exposed by electrons

    E-Print Network [OSTI]

    Béché, A; Van Tendeloo, G; Verbeeck, J

    2013-01-01T23:59:59.000Z

    Magnetic monopoles have provided a rich field of study, leading to a wide area of research in particle physics, solid state physics, ultra-cold gases, superconductors, cosmology, and gauge theory. So far, no true magnetic monopoles were found experimentally. Using the Aharonov-Bohm effect, one of the central results of quantum physics, shows however, that an effective monopole field can be produced. Understanding the effects of such a monopole field on its surroundings is crucial to its observation and provides a better grasp of fundamental physical theory. We realize the diffraction of fast electrons at a magnetic monopole field generated by a nanoscopic magnetized ferromagnetic needle. Previous studies have been limited to theoretical semiclassical optical calculations of the motion of electrons in such a monopole field. Solid state systems like the recently studied 'spin ice' provide a constrained system to study similar fields, but make it impossible to separate the monopole from the material. Free space ...

  12. Laced permanent magnet quadrupole drift tube magnets

    SciTech Connect (OSTI)

    Feinberg, B.; Behrsing, G.U.; Halbach, K.; Marks, J.S.; Morrison, M.E.; Nelson, D.H.

    1988-10-01T23:59:59.000Z

    A laced permanent magnet quadrupole drift tube magnet has been constructed for a proof-of-principle test. The magnet is a conventional tape-wound quadrupole electromagnet, using iron pole- pieces, with the addition of permanent magnet material (neodymium iron) between the poles to reduce the effects of saturation. The iron is preloaded with magnetic flux generated by the permanent magnet material, resulting in an asymmetrical saturation curve. Since the polarity of the quadrupole magnets in a drift tube linac is not reversed we can take advantage of this asymmetrical saturation to provide greater focusing strength. The magnet configuration has been optimized and the vanadium permendur poles needed in a conventional quadrupole have been replaced with iron poles. The use of permanent magnet material has allowed us to increase the focusing strength of the magnet by about 20% over that of a conventional tape-wound quadrupole. Comparisons will be made between this magnet and the conventional tape-wound quadrupole. 3 refs., 5 figs.

  13. Introduction Magnetic Anisotropy of

    E-Print Network [OSTI]

    Rossak, Wilhelm R.

    not completely understood interesting for dilute magnetic semiconductors (DMSs) transparent ferromagnets

  14. Magnetic Imaging Wolfgang Kuch

    E-Print Network [OSTI]

    Kuch, Wolfgang

    Magnetic Imaging Wolfgang Kuch Freie Universit¨at Berlin, Institut f¨ur Experimentalphysik, Arnimallee 14, 14195 Berlin, Germany kuch@physik.fu-berlin.de Abstract. Imaging of magnetic domains has- ern techniques is used nowadays routinely for magnetic imaging of magnetic ma- terials

  15. Superconducting Magnet Division

    E-Print Network [OSTI]

    McDonald, Kirk

    Superconducting Magnet Division Ramesh Gupta 20T Target Solenoid with HTS Insert Solenoid Capture Laboratory New York, USA http://www.bnl.gov/magnets/staff/gupta #12;Superconducting Magnet Division Ramesh of HTS may significantly reduce the amount of Tungsten shielding · Summary #12;Superconducting Magnet

  16. U.S. Rare Earth Magnet Patents Table © 2-4-2015 page 1

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    to a temperature equal to or lower than a sintering temperature of the magnet base material, wherein: a) a content of a rare earth in a metallic state in the magnet base...

  17. Effect of Field Dependent Core Size on Reversible Magnetization of High-? Superconductors

    SciTech Connect (OSTI)

    Kogan, V. G. [Ames Laboratory and Iowa State University; Prozorov, R. [Ames Laboratory and Iowa State University; Bud'ko, S. L. [Ames Laboratory; Canfield, P. C. [Ames Laboratory; Thompson, James R [ORNL; Karpinski, J. [Swiss Federal Institute of Technology; Zhigadlo, N. D. [Swiss Federal Institute of Technology; Miranovic, P. [University of Montenegro, Serbia and Montenegro

    2006-01-01T23:59:59.000Z

    The field dependence of the vortex core size {zeta}(B) is incorporated in the London model, in order to describe reversible magnetization M(B,T) for a number of materials with large Ginzburg-Landau parameter {kappa}. The dependence {zeta}(B) is directly related to deviations in M(ln B) from linear behavior prescribed by the standard London model. A simple method to extract {zeta}(B) from the magnetization data is proposed. For most materials examined, {zeta}(B) so obtained decreases with increasing field and is in qualitative agreement both with behavior extracted from {micro}SR and small-angle neutron-scattering data and with that predicted theoretically.

  18. Nanocomposite Magnets: Transformational Nanostructured Permanent Magnets

    SciTech Connect (OSTI)

    None

    2010-10-01T23:59:59.000Z

    Broad Funding Opportunity Announcement Project: GE is using nanomaterials technology to develop advanced magnets that contain fewer rare earth materials than their predecessors. Nanomaterials technology involves manipulating matter at the atomic or molecular scale, which can represent a stumbling block for magnets because it is difficult to create a finely grained magnet at that scale. GE is developing bulk magnets with finely tuned structures using iron-based mixtures that contain 80% less rare earth materials than traditional magnets, which will reduce their overall cost. These magnets will enable further commercialization of HEVs, EVs, and wind turbine generators while enhancing U.S. competitiveness in industries that heavily utilize these alternatives to rare earth minerals.

  19. Magnetic infrasound sensor

    DOE Patents [OSTI]

    Mueller, Fred M. (Los Alamos, NM); Bronisz, Lawrence (Los Alamos, NM); Grube, Holger (Los Alamos, NM); Nelson, David C. (Santa Fe, NM); Mace, Jonathan L. (Los Alamos, NM)

    2006-11-14T23:59:59.000Z

    A magnetic infrasound sensor is produced by constraining a permanent magnet inside a magnetic potential well above the surface of superconducting material. The magnetic infrasound sensor measures the position or movement of the permanent magnet within the magnetic potential well, and interprets the measurements. Infrasound sources can be located and characterized by combining the measurements from one or more infrasound sensors. The magnetic infrasound sensor can be tuned to match infrasound source types, resulting in better signal-to-noise ratio. The present invention can operate in frequency modulation mode to improve sensitivity and signal-to-noise ratio. In an alternate construction, the superconductor can be levitated over a magnet or magnets. The system can also be driven, so that time resolved perturbations are sensed, resulting in a frequency modulation version with improved sensitivity and signal-to-noise ratio.

  20. Tamper resistant magnetic stripes

    DOE Patents [OSTI]

    Naylor, Richard Brian (Albuquerque, NM); Sharp, Donald J. (Albuquerque, NM)

    1999-01-01T23:59:59.000Z

    This invention relates to a magnetic stripe comprising a medium in which magnetized particles are suspended and in which the encoded information is recorded by actual physical rotation or alignment of the previously magnetized particles within the flux reversals of the stripe which are 180.degree. opposed in their magnetic polarity. The magnetized particles are suspended in a medium which is solid, or physically rigid, at ambient temperatures but which at moderately elevated temperatures, such as 40.degree. C., is thinable to a viscosity permissive of rotation of the particles therein under applications of moderate external magnetic field strengths within acceptable time limits.