Dynamics of Magnetized Vortex Tubes in the Solar Chromosphere
Kitiashvili, I N; Mansour, N N; Wray, A A
2012-01-01
We use 3D radiative MHD simulations to investigate the formation and dynamics of small-scale (less than 0.5 Mm in diameter) vortex tubes spontaneously generated by turbulent convection in quiet-Sun regions with initially weak mean magnetic fields. The results show that the vortex tubes penetrate into the chromosphere and substantially affect the structure and dynamics of the solar atmosphere. The vortex tubes are mostly concentrated in intergranular lanes and are characterized by strong (near sonic) downflows and swirling motions that capture and twist magnetic field lines, forming magnetic flux tubes that expand with height and which attain magnetic field strengths ranging from 200 G in the chromosphere to more than 1 kG in the photosphere. We investigate in detail the physical properties of these vortex tubes, including thermodynamic properties, flow dynamics, and kinetic and current helicities, and conclude that magnetized vortex tubes provide an important path for energy and momentum transfer from the con...
X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation
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alloy) revealed a way to easily switch the vortex polarization with a small alternating electrical current, but how the switching actually occurred has remained speculative in...
Distinct magnetic signatures of fractional vortex configurations in multiband superconductors
Silva, R. M. da; Domínguez, D.; Aguiar, J. Albino
2014-12-08
Vortices carrying fractions of a flux quantum are predicted to exist in multiband superconductors, where vortex core can split between multiple band-specific components of the superconducting condensate. Using the two-component Ginzburg-Landau model, we examine such vortex configurations in a two-band superconducting slab in parallel magnetic field. The fractional vortices appear due to the band-selective vortex penetration caused by different thresholds for vortex entry within each band-condensate, and stabilize near the edges of the sample. We show that the resulting fractional vortex configurations leave distinct fingerprints in the static measurements of the magnetization, as well as in ac dynamic measurements of the magnetic susceptibility, both of which can be readily used for the detection of these fascinating vortex states in several existing multiband superconductors.
Magnetic Vortex Core Reversal by Low-Field Excitations
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Magnetic Vortex Core Reversal by Low-Field Excitations Magnetic Vortex Core Reversal by Low-Field Excitations Print Wednesday, 28 March 2007 00:00 In micrometer-sized magnetic thin...
X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation
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Experimental investigation of magnetic anisotropy in spin vortex discs
Garraud, N. Arnold, D. P.
2014-05-07
We present experimental 2D vector vibrating sample magnetometer measurements to demonstrate the shape anisotropy effects occurring in micrometer-diameter supermalloy spin vortex discs. Measurements made for different disc sizes and orientations confirm the out-of-plane susceptibility is several orders of magnitude smaller than the in-plane susceptibility. These results validate with a high certitude that spin vortices with high diameter to thickness ratio retain in-plane-only magnetization, even when subjected to fields in the out-of-plane direction. These results contribute to further computational simulations of the dynamics of spin vortex structures in colloidal suspensions where external fields may be applied in any arbitrary direction.
Vortex dynamics in 4 Banavara N. Shashikanth
Shashikanth, Banavara N.
of oblique vortex shedding behind a heated circular cylinder in laminar wake regime Phys. Fluids 24, 011701 dynamics of Euler's equations for a constant density fluid flow in R4 is studied. Most of the paper focuses of such work are in Refs. 31, 24, 12, 14, and 11. It is fair to say that, in general, classical fluid flows
Electron vortex beams in a magnetic field and spin filter
Debashree Chowdhury; Banasri Basu; Pratul Bandyopadhyay
2015-02-25
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.
Riemannian geometrical constraints on magnetic vortex filaments in plasmas
L. C. Garcia de Andrade
2005-10-16
Two theorems on the Riemannian geometrical constraints on vortex magnetic filaments acting as dynamos in (MHD) flows are presented. The use of Gauss-Mainard-Codazzi equations allows us to investigate in detail the influence of curvature and torsion of vortex filaments in the MHD dynamos. This application follows closely previous applications to Heisenberg spin equation to the investigations in magnetohydrostatics given by Schief (Plasma Physics J. 10, 7, 2677 (2003)). The Lorentz force on vortex filaments are computed and the ratio between the forces along different directions are obtained in terms of the ratio between the corresponding magnetic fields which equals also the ratio between the Frenet torsion and vortex line curvature. A similar relation between Lorentz forces, magnetic fields and twist, which is proportional to total torsion integral has been obtained by Ricca (Fluid Dyn. Res. 36,319 (2005)) in the case of inflexional desiquilibrium of magnetic flux-tubes. This is due to the fact that the magnetic vortex lines are a limit case of the magnetic flux-tubes when the lenght of the tube is much greater than the radius of the tube. Magnetic helicity equation of the filament allows us again to determine the magnetic fields ratio from Frenet curvature and torsion of the vortex lines.
Ubiquitous Solar Eruptions Driven by Magnetized Vortex Tubes
Kitiashvili, I N; Lele, S K; Mansour, N N; Wray, A A
2013-01-01
The solar surface is covered by high-speed jets transporting mass and energy into the solar corona and feeding the solar wind. The most prominent of these jets have been known as spicules. However, the mechanism initiating these eruptions events is still unknown. Using realistic numerical simulations we find that small-scale eruptions are produced by ubiquitous magnetized vortex tubes generated by the Sun's turbulent convection in subsurface layers. The swirling vortex tubes (resembling tornadoes) penetrate into the solar atmosphere, capture and stretch background magnetic field, and push surrounding material up, generating quasiperiodic shocks. Our simulations reveal a complicated high-speed flow patterns, and thermodynamic and magnetic structure in the erupting vortex tubes. We found that the eruptions are initiated in the subsurface layers and are driven by the high-pressure gradients in the subphotosphere and photosphere, and by the Lorentz force in the higher atmosphere layers.
Spectro-Polarimetric Properties of Small-Scale Plasma Eruptions Driven by Magnetic Vortex Tubes
Kitiashvili, Irina N
2014-01-01
Highly turbulent nature of convection on the Sun causes strong multi-scale interaction of subsurface layers with the photosphere and chromosphere. According to realistic 3D radiative MHD numerical simulations ubiquitous small-scale vortex tubes are generated by turbulent flows below the visible surface and concentrated in the intergranular lanes. The vortex tubes can capture and amplify magnetic field, penetrate into chromospheric layers and initiate quasi-periodic flow eruptions that generates Alfv\\'enic waves, transport mass and energy into the solar atmosphere. The simulations revealed high-speed flow patterns, and complicated thermodynamic and magnetic structures in the erupting vortex tubes. The spontaneous eruptions are initiated and driven by strong pressure gradients in the near-surface layers, and accelerated by the Lorentz force in the low chromosphere. In this paper, the simulation data are used to further investigate the dynamics of the eruptions, their spectro-polarimetric characteristics for the...
Origin and dynamics of vortex rings in drop splashing
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Lee, Ji San; Park, Su Ji; Lee, Jun Ho; Weon, Byung Mook; Fezzaa, Kamel; Je, Jung Ho
2015-09-04
A vortex is a flow phenomenon that is very commonly observed in nature. More than a century, a vortex ring that forms during drop splashing has caught the attention of many scientists due to its importance in understanding fluid mixing and mass transport processes. However, the origin of the vortices and their dynamics remain unclear, mostly due to the lack of appropriate visualization methods. Here, with ultrafast X-ray phase-contrast imaging, we show that the formation of vortex rings originates from the energy transfer by capillary waves generated at the moment of the drop impact. Interestingly, we find a row ofmore »vortex rings along the drop wall, as demonstrated by a phase diagram established here, with different power-law dependencies of the angular velocities on the Reynolds number. These results provide important insight that allows understanding and modelling any type of vortex rings in nature, beyond just vortex rings during drop splashing.« less
Fast chirality reversal of the magnetic vortex by electric current
Lim, W. L. Liu, R. H.; Urazhdin, S.; Tyliszczak, T.; Erokhin, S. G.; Berkov, D.
2014-12-01
The possibility of high-density information encoding in magnetic materials by topologically stable inhomogeneous magnetization configurations such as domain walls, skyrmions, and vortices has motivated intense research into mechanisms enabling their control and detection. While the uniform magnetization states can be efficiently controlled by electric current using magnetic multilayer structures, this approach has proven much more difficult to implement for inhomogeneous states. Here, we report direct observation of fast reversal of magnetic vortex by electric current in a simple planar structure based on a bilayer of spin Hall material Pt with a single microscopic ferromagnetic disk contacted by asymmetric electrodes. The reversal is enabled by a combination of the chiral Oersted field and spin current generated by the nonuniform current distribution in Pt. Our results provide a route for the efficient control of inhomogeneous magnetization configurations by electric current.
Magnetic Vortex Core Reversal by Low-Field Excitations
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousandReport) |Administration SavannahMagnetic Vortex CoreMagnetic
Magnetic Vortex Core Reversal by Low-Field Excitations
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Magnetic Vortex Core Reversal by Low-Field Excitations
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousandReport) |Administration SavannahMagneticMagnetic Vortex Core
Laboratory Analysis of Vortex Dynamics For Shallow Tidal Inlets
Whilden, Kerri Ann
2010-10-12
OF VORTEX DYNAMICS FOR SHALLOW TIDAL INLETS A Thesis by KERRI ANN WHILDEN Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements for the degree of MASTER OF SCIENCE August 2009 Major Subject: Ocean... Engineering LABORATORY ANALYSIS OF VORTEX DYNAMICS FOR SHALLOW TIDAL INLETS A Thesis by KERRI ANN WHILDEN Submitted to the O ce of Graduate Studies of Texas A&M University in partial ful llment of the requirements for the degree of MASTER OF SCIENCE Approved...
Magnetic Vortex Core Reversal by Low-Field Excitations
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switching mechanism, which can be understood within the framework of micromagnetic theory, gives insights into basic magnetization dynamics and their possible application to...
Magnetic Vortex Core Reversal by Low-Field Excitations
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousandReport) |Administration SavannahMagnetic Vortex Core
Magnetic Vortex Core Reversal by Low-Field Excitations
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PHYSICAL REVIEW E 78, 036304 2008 Variational principle in dynamics of a vortex ...lament
Berdichevsky, Victor
A vortex ...lament is a thin tube such that vorticity is negligible in a vicinity of this tube while insidePHYSICAL REVIEW E 78, 036304 2008 Variational principle in dynamics of a vortex ...lament Victor L in dynamics of vortex ...lament Victor L. Berdichevsky Mechanical Engineering, Wayne State University, Detroit
Vortex in a relativistic perfect isentropic fluid and Nambu Goto dynamics
B. Boisseau
1999-11-26
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
Vortex driven flame dynamics and combustion instability
Altay, Hurrem Murat
2005-01-01
Combustion instability in premixed combustors mostly arises due to the coupling between heat release rate dynamics and system acoustics. It is crucial to understand the instability mechanisms to design reliable, high ...
Determination of magnetic vortex chirality using lateral spin-valve and Y. Otani
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
Method for the detection of a magnetic field utilizing a magnetic vortex
Novosad, Valentyn (Chicago, IL); Buchanan, Kristen (Batavia, IL)
2010-04-13
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.
The role of vortex wake dynamics in the flow-induced vibration of tube arrays
Kevlahan, Nicholas
The role of vortex wake dynamics in the flow-induced vibration of tube arrays N.K.-R. Kevlahan Keywords: Fluidstructure interaction Vortex-induced vibration Tube arrays Potential flow a b s t r a c in the non-resonant flow-induced vibration of periodic tube arrays. This dual approach untangles the effects
Magnetic monopole versus vortex as gauge-invariant topological objects for quark confinement
Kondo, Kei-Ichi; Shinohara, Toru; Shibata, Akihiro; Kato, Seikou
2015-01-01
First, we give a gauge-independent definition of chromomagnetic monopoles in $SU(N)$ Yang-Mills theory which is derived through a non-Abelian Stokes theorem for the Wilson loop operator. Then we discuss how such magnetic monopoles can give a nontrivial contribution to the Wilson loop operator for understanding the area law of the Wilson loop average. Next, we discuss how the magnetic monopole condensation picture are compatible with the vortex condensation picture as another promising scenario for quark confinement. We analyze the profile function of the magnetic flux tube as the non-Abelian vortex solution of $U(N)$ gauge-Higgs model, which is to be compared with numerical simulations of the $SU(N)$ Yang-Mills theory on a lattice. This analysis gives an estimate of the string tension based on the vortex condensation picture, and possible interactions between two non-Abelian vortices.
Magnetic monopole versus vortex as gauge-invariant topological objects for quark confinement
Kei-Ichi Kondo; Takaaki Sasago; Toru Shinohara; Akihiro Shibata; Seikou Kato
2015-08-08
First, we give a gauge-independent definition of chromomagnetic monopoles in $SU(N)$ Yang-Mills theory which is derived through a non-Abelian Stokes theorem for the Wilson loop operator. Then we discuss how such magnetic monopoles can give a nontrivial contribution to the Wilson loop operator for understanding the area law of the Wilson loop average. Next, we discuss how the magnetic monopole condensation picture are compatible with the vortex condensation picture as another promising scenario for quark confinement. We analyze the profile function of the magnetic flux tube as the non-Abelian vortex solution of $U(N)$ gauge-Higgs model, which is to be compared with numerical simulations of the $SU(N)$ Yang-Mills theory on a lattice. This analysis gives an estimate of the string tension based on the vortex condensation picture, and possible interactions between two non-Abelian vortices.
Magnetic vortex crystal formation in the antidot complement of square artificial spin ice
Araujo, C. I. L. de Silva, R. C.; Ribeiro, I. R. B.; Nascimento, F. S.; Felix, J. F.; Ferreira, S. O.; Moura-Melo, W. A.; Pereira, A. R.; Mól, L. A. S.
2014-03-03
We have studied ferromagnetic nickel thin films patterned with square lattices of elongated antidots that are negative analogues of square artificial spin ice. Micromagnetic simulations and direct current magnetic moment measurements reveal in-plane anisotropy of the magnetic hysteresis loops, and the formation of a dense array of magnetic vortices with random polarization and chirality. These multiply-connected antidot arrays could be superior to lattices of disconnected nanodisks for investigations of vortex switching by applied electric current.
Magnetic Vortex Core Reversal by Low-Field Excitations
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these structures are highly stable, very strong magnetic fields of around half a tesla (approximately one-third the field of the strongest permanent magnet) were previously...
Spin waves in circular soft magnetic dots at the crossover between vortex and single domain state
Metlushko, Vitali
Facility, Cornell University, Ithaca, New York, 14853 USA 6Departamento de Fisica de Materiales We report on linear spin dynamics in the vortex state of Permalloy cylindrical dots subjected In many physical systems such as liquids, plasma, super- conductors, ferromagnets, etc., the topological
Model for dynamic self-assembled magnetic surface structures.
Belkin, M.; Glatz, A.; Snezhko, A.; Aranson, I. S.; Materials Science Division; Northwestern Univ.
2010-07-07
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.
Mascia, Corrado
Vortex dynamics in three-dimensional continuous myocardium with fiber rotation: Filament, or filament. This twist can then significantly alter the dynamics of the filament. This paper explores transmural filament and cause a transition to a wave turbulent state characterized by a high density
Magnetic Vortex Core Reversal by Low-Field Excitations
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousandReport) |Administration SavannahMagnetic
Vortex-Pair Dynamics in Anisotropic Bistable Media: A Kinematic Approach Aric Hagberg1
Meron, Ehud
Alamos, New Mexico 87545, USA 2 Department of Solar Energy and Environmental Physics, BIDR, Ben Gurion type upon rotation by =2. We study vortex-pair dynamics by deriving kinematic equations for a front with contour lines that form a closed loop. Equations of this kind, but for isotropic systems and infinite
Magnetic Vortex Core Reversal by Low-Field Excitations
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformationJesse BergkampCentermillion toMSDS on the internet TheLaboratoryMagnetic
Dynamic Switching of the Spin Circulation in Tapered Magnetic...
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phenomenon which is found across a large range of length scales, from galaxies to hurricanes and even down to the nanoscale as in superconducting materials. Magnetic vortex...
B. Boisseau
1999-01-18
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.
Meissner Effect and Vortex Dynamics in Quark Stars -- A Model for Soft Gamma-Ray Repeaters
R. Ouyed; O. Elgaroy; H. Dahle; P. Keranen
2004-03-24
We present a new model for soft gamma-ray repeaters based on a quark star born with temperatures above the critical value (T_c) for the onset of the colour-flavor locked superconductivity. The quark star then quickly cools below T_c, expelling a fraction of the surface magnetic field via the Meissner effect. We show that if a small fraction (\\leq 10%) of the surface magnetic field (10^{14} - 10^{15} {\\rm G}) is expelled, it quickly decays via magnetic reconnection and heats up the quark star surface to temperatures > 10^9 {\\rm K}. Created (e^{+},e^{-}) pairs annihilate into gamma rays emitted in a giant burst (the first burst in our model), with a luminosity of \\sim 10^{45} {\\rm ergs} {\\rm s}^{-1}. Subsequent bursts result from the restructuring of the surface magnetic field following the formation and relaxation of a vortex lattice which confines the internal magnetic field. During this phase, energy is sporadically released as a consequence of magnetic reconnection events in the entangled surface magnetic field as it evolves into a smooth, more stable, configuration. The star eventually enters a quiescent phase in which energy is continuously supplied by vortex annihilation at the surface. As the star spins down, the outermost vortex lines will be pushed to the surface where they annihilate and release their confined magnetic field. We show that the corresponding luminosity is L_v \\sim 10^{36} {\\rm ergs} {\\rm s}^{-1} for a typical soft gamma-ray repeater spinning with a period of 8 {\\rm s} and a surface magnetic field not exceeding 10^{15} {\\rm G}. Our model can be applied to any situation where a T>T_{\\rm c} quark star is generated. We discuss the connection between anomalous X-ray pulsars and soft gamma-ray repeaters in the context of our model.
Gradient catastrophe and flutter in vortex filament dynamics
B. G. Konopelchenko; G. Ortenzi
2011-06-02
Gradient catastrophe and flutter instability in the motion of vortex filament within the localized induction approximation are analyzed. It is shown that the origin if this phenomenon is in the gradient catastrophe for the dispersionless Da Rios system which describes motion of filament with slow varying curvature and torsion. Geometrically this catastrophe manifests as a rapid oscillation of a filament curve in a point that resembles the flutter of airfoils. Analytically it is the elliptic umbilic singularity in the terminology of the catastrophe theory. It is demonstrated that its double scaling regularization is governed by the Painlev\\'e-I equation.
First-Order Transition in the Magnetic Vortex Matter in Superconducting MgB2 Tuned by Disorder
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
Vortex Zero Modes, Large Flux Limit and Ambjørn-Nielsen-Olesen Magnetic Instabilities
Stefano Bolognesi; Chandrasekhar Chatterjee; Sven Bjarke Gudnason; Kenichi Konishi
2014-09-23
In the large flux limit vortices become flux tubes with almost constant magnetic field in the interior region. This occurs in the case of non-Abelian vortices as well, and the study of such configurations allows us to reveal a close relationship between vortex zero modes and the gyromagnetic instabilities of vector bosons in a strong background magnetic field discovered by Nielsen, Olesen and Ambj{\\o}rn. The BPS vortices are exactly at the onset of this instability, and the dimension of their moduli space is precisely reproduced in this way. We present a unifying picture in which, through the study of the linear spectrum of scalars, fermions and W bosons in the magnetic field background, the expected number of translational, orientational, fermionic as well as semilocal zero modes is correctly reproduced in all cases.
Vortex Tubes of Turbulent Solar Convection
Kitiashvili, I N; Mansour, N N; Lele, S K; Wray, A A
2011-01-01
Investigation of turbulent properties of solar convection is extremely important for understanding of the multi-scale dynamics observed on the solar surface. In particular, recent high-resolution observations revealed ubiquitous vortical structures, and numerical simulations demonstrated links between the vortex tube dynamics and magnetic field organization, and also importance of vortex tube interactions in the mechanism of acoustic wave excitation on the Sun. In this paper we investigate mechanisms of formation of vortex tubes in highly-turbulent convective flows near the solar surface by using realistic radiative hydrodynamic LES simulations. Analysis of data, obtained by the simulations, indicates two basic processes of the vortex tube formation: 1) development of small-scale convective instability inside convective granules, and 2) a Kelvin-Helmholtz type instability of shearing flows in intergranular lanes. Our analysis shows that vortex stretching during these processes is a primary source of generatio...
Ultra-fast magnetic vortex core reversal by a local field pulse
Rückriem, R.; Albrecht, M., E-mail: manfred.albrecht@physik.uni-augsburg.de [Institute of Physics, Chemnitz University of Technology, 09107 Chemnitz (Germany); Schrefl, T. [St. Pölten University of Applied Science, 3100 St. Pölten (Austria)
2014-02-03
Magnetic vortex core reversal of a 20-nm-thick permalloy disk with a diameter of 100?nm was studied by micromagnetic simulations. By applying a global out-of-plane magnetic field pulse, it turned out that the final core polarity is very sensitive to pulse width and amplitude, which makes it hard to control. The reason for this phenomenon is the excitation of radial spin waves, which dominate the reversal process. The excitation of spin waves can be strongly suppressed by applying a local field pulse within a small area at the core center. With this approach, ultra-short reversal times of about 15 ps were achieved, which are ten times faster compared to a global pulse.
B. G. Konopelchenko; G. Ortenzi
2012-06-13
Quasiclassical approximation in the intrinsic description of the vortex filament dynamics is discussed. Within this approximation the governing equations are given by elliptic system of quasi-linear PDEs of the first order. Dispersionless Da Rios system and dispersionless Hirota equation are among them. They describe motion of vortex filament with slow varying curvature and torsion without or with axial flow. Gradient catastrophe for governing equations is studied. It is shown that geometrically this catastrophe manifests as a fast oscillation of a filament curve around the rectifying plane which resembles the flutter of airfoils. Analytically it is the elliptic umbilic singularity in the terminology of the catastrophe theory. It is demonstrated that its double scaling regularization is governed by the Painleve' I equation.
Analytic treatment of vortex states in cylindrical superconductors in applied axial magnetic field
Ludu, A.; Van Deun, J.; Cuyt, A.; Milosevic, M. V.; Peeters, F. M.
2010-08-15
We solve the linear Ginzburg-Landau (GL) equation in the presence of a uniform magnetic field with cylindrical symmetry and we find analytic expressions for the eigenfunctions in terms of the confluent hypergeometric functions. The discrete spectrum results from an implicit equation associated to the boundary conditions and it is resolved in analytic form using the continued fractions formalism. We study the dependence of the spectrum and the eigenfunctions on the sample size and the surface conditions for solid and hollow cylindrical superconductors. Finally, the solutions of the nonlinear GL formalism are constructed as expansions in the linear GL eigenfunction basis and selected by minimization of the free energy. We present examples of vortex states and their energies for different samples in enhancing/suppressing superconductivity surroundings.
Vortex-type elastic structured media and dynamic shielding
Michele Brun; Ian S. Jones; Alexander B. Movchan
2012-01-27
The paper addresses a novel model of metamaterial structure. A system of spinners has been embedded into a two-dimensional periodic lattice system. The equations of motion of spinners are used to derive the expression for the chiral term in the equations describing the dynamics of the lattice. Dispersion of elastic waves is shown to possess innovative filtering and polarization properties induced by the vortextype nature of the structured media. The related homogenised effective behavior is obtained analytically and it has been implemented to build a shielding cloak around an obstacle. Analytical work is accompanied by numerical illustrations.
Fani Sani, F., E-mail: fanisani@ualberta.ca, E-mail: mark.freeman@ualberta.ca; Losby, J. E.; Diao, Z.; Parsons, L. C.; Burgess, J. A. J.; Hiebert, W. K.; Freeman, M. R., E-mail: fanisani@ualberta.ca, E-mail: mark.freeman@ualberta.ca [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2G7 (Canada); National Institute for Nanotechnology (NINT), Edmonton, Alberta T6G 2M9 (Canada); Vick, D. [National Institute for Nanotechnology (NINT), Edmonton, Alberta T6G 2M9 (Canada)
2014-05-07
Artificial vortex core pinning sites are induced in thin Permalloy disks by point exposure to as few as 10?000 ions from a focused Ga{sup +} beam. These pinning sites yield a first-order change in the magnetization response of the disk. A single site can keep the vortex core pinned over an applied field range comparable to the vortex annihilation field of the unaltered disk. Several widely separated sites can work together to keep the core pinned in one place, while the Barkhausen effect is eliminated from the magnetization curve over a range approaching the saturation moment of the disk.
Quantitative Modeling of High Temperature Magnetization Dynamics
Zhang, Shufeng
2009-03-01
Final Technical Report Project title: Quantitative Modeling of High Temperature Magnetization Dynamics DOE/Office of Science Program Manager Contact: Dr. James Davenport
The Holographic Superconductor Vortex
Marc Montull; Alex Pomarol; Pedro J. Silva
2009-09-02
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.
Flame-vortex interaction driven combustion dynamics in a backward-facing step combustor
Altay, H. Murat; Speth, Raymond L.; Hudgins, Duane E.; Ghoniem, Ahmed F.
2009-05-15
The combustion dynamics of propane-hydrogen mixtures are investigated in an atmospheric pressure, lean, premixed backward-facing step combustor. We systematically vary the equivalence ratio, inlet temperature and fuel composition to determine the stability map of the combustor. Simultaneous pressure, velocity, heat release rate and equivalence ratio measurements and high-speed video from the experiments are used to identify and characterize several distinct operating modes. When fuel is injected far upstream from the step, the equivalence ratio entering the flame is temporally and spatially uniform, and the combustion dynamics are governed only by flame-vortex interactions. Four distinct dynamic regimes are observed depending on the operating parameters. At high but lean equivalence ratios, the flame is unstable and oscillates strongly as it is wrapped around the large unsteady wake vortex. At intermediate equivalence ratios, weakly oscillating quasi-stable flames are observed. Near the lean blowout limit, long stable flames extending from the corner of the step are formed. At atmospheric inlet temperature, the unstable mode resonates at the 1/4 wavemode of the combustor. As the inlet temperature is increased, the 5/4 wavemode of the combustor is excited at high but lean equivalence ratios, forming the high-frequency unstable flames. Higher hydrogen concentration in the fuel and higher inlet temperatures reduce the equivalence ratios at which the transitions between regimes are observed. We plot combustion dynamics maps or the response curves, that is the overall sound pressure level as a function of the equivalence ratio, for different operating conditions. We demonstrate that numerical results of strained premixed flames can be used to collapse the response curves describing the transitions among the dynamic modes onto a function of the heat release rate parameter alone, rather than a function dependent on the equivalence ratio, inlet temperature and fuel composition separately. We formulate a theory for predicting the critical values of the heat release parameter at which quasi-stable to unstable and unstable to high-frequency unstable modes take place. (author)
Chiral specific electron vortex beam spectroscopy
J. Yuan; S. M. Lloyd; M. Babiker
2013-07-29
Electron vortex beams carry well-defined orbital angular momentum (OAM) about the propagation axis. Such beams are thus characterised by chirality features which make them potentially useful as probes of magnetic and other chiral materials. An analysis of the inelastic processes in which electron vortex beams interact with atoms and which involve OAM exchange is outlined, leading to the multipolar selection rules governing this chiral specific electron vortex beam spectroscopy. Our results show clearly that the selection rules are dependent on the dynamical state and location of the atoms involved. In the most favorable scenario, this form of electron spectroscopy can induce magnetic sublevel transitions which are commonly probed using circularly polarized photon beams.
Transition between vortex rings and MAP solutions for electrically charged magnetic solutions
Wong, Khai-Ming; Soltanian, Amin; Teh, Rosy
2014-03-05
We consider the bifurcation and transition of axially symmetric monopole-antimonopole pair (MAP) and vortex ring solutions in the presence of electric charge for the SU(2) Yang-Mills-Higgs field theory. Here we investigate the properties of MAP/vortex ring solutions with n = 3,? = 0.65, for different Higgs field strength ?. For ? < 4.93, there is only one fundamental branch of vortex ring solution, but at the critical value of ?{sub b} = 4.93, branching happens and 2 sets of new solutions appeared. The new branch with less energy is a full MAP solution while the branch with higher energy contains MAP at the beginning and separation between poles of MAP on the z-axis reduces gradually and at another critical value of ?{sub t} = 14.852, they merge together at z = 0. Beyond this point the solutions change to the vortex ring solutions and a transitions between MAP and vortex ring solutions happens at this branch.
GREEN'S FUNCTIONS OF VORTEX OPERATORS
Polchinski, Joseph
2013-01-01
8 g Olesen vortex • , somewhere in space. The tube between cvortex operators have surface clustering, as this implies that magnetic flux is forming into tubes.
Vortex Lattices and Crystalline Geometries
Ning Bao; Sarah Harrison; Shamit Kachru; Subir Sachdev
2013-04-16
We consider $AdS_2 \\times R^2$ solutions supported by a magnetic field, such as those which arise in the near-horizon limit of magnetically charged $AdS_4$ Reissner-Nordstrom black branes. In the presence of an electrically charged scalar field, such magnetic solutions can be unstable to spontaneous formation of a vortex lattice. We solve the coupled partial differential equations which govern the charged scalar, gauge field, and metric degrees of freedom to lowest non-trivial order in an expansion around the critical point, and discuss the corrections to the free energy and thermodynamic functions arising from the formation of the lattice. We describe how such solutions can also be interpreted, via S-duality, as characterizing infrared crystalline phases of conformal field theories doped by a chemical potential, but in zero magnetic field; the doped conformal field theories are dual to geometries that exhibit dynamical scaling and hyperscaling violation.
Development of vortex state in circular magnetic nanodots: Theory and experiment RID A-9247-2009
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.
2010-01-01
in a variety of spintronics and magnetic storage applications, including magnetic bit- patterned media and magnetic random access memory. One of the most studied types of such structures are nanoscaled disks denoted as ?nanodots? which have been...
Effects of trailing edge flap dynamic deployment on blade-vortex interactions
Nelson, Carter T.
1997-01-01
A theoretical and experimental investigation is undertaken to determine the effects of an actively deployable trailing edge flap on the disturbances created during blade-vortex interactions (BVI). The theoretical model consists of an unsteady panel...
Dynamically stable magnetic suspension/bearing system
Post, R.F.
1996-02-27
A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw`s Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements. 32 figs.
Dynamically stable magnetic suspension/bearing system
Post, Richard F. (Walnut Creek, CA)
1996-01-01
A magnetic bearing system contains magnetic subsystems which act together to support a rotating element in a state of dynamic equilibrium. However, owing to the limitations imposed by Earnshaw's Theorem, the magnetic bearing systems to be described do not possess a stable equilibrium at zero rotational speed. Therefore, mechanical stabilizers are provided, in each case, to hold the suspended system in equilibrium until its speed has exceeded a low critical speed where dynamic effects take over, permitting the achievement of a stable equilibrium for the rotating object. A state of stable equilibrium is achieved above a critical speed by use of a collection of passive elements using permanent magnets to provide their magnetomotive excitation. The magnetic forces exerted by these elements, when taken together, levitate the rotating object in equilibrium against external forces, such as the force of gravity or forces arising from accelerations. At the same time, this equilibrium is made stable against displacements of the rotating object from its equilibrium position by using combinations of elements that possess force derivatives of such magnitudes and signs that they can satisfy the conditions required for a rotating body to be stably supported by a magnetic bearing system over a finite range of those displacements.
MULTISCALE DYNAMICS OF SOLAR MAGNETIC STRUCTURES
Uritsky, Vadim M.; Davila, Joseph M.
2012-03-20
Multiscale topological complexity of the solar magnetic field is among the primary factors controlling energy release in the corona, including associated processes in the photospheric and chromospheric boundaries. We present a new approach for analyzing multiscale behavior of the photospheric magnetic flux underlying these dynamics as depicted by a sequence of high-resolution solar magnetograms. The approach involves two basic processing steps: (1) identification of timing and location of magnetic flux origin and demise events (as defined by DeForest et al.) by tracking spatiotemporal evolution of unipolar and bipolar photospheric regions, and (2) analysis of collective behavior of the detected magnetic events using a generalized version of the Grassberger-Procaccia correlation integral algorithm. The scale-free nature of the developed algorithms makes it possible to characterize the dynamics of the photospheric network across a wide range of distances and relaxation times. Three types of photospheric conditions are considered to test the method: a quiet photosphere, a solar active region (NOAA 10365) in a quiescent non-flaring state, and the same active region during a period of M-class flares. The results obtained show (1) the presence of a topologically complex asymmetrically fragmented magnetic network in the quiet photosphere driven by meso- and supergranulation, (2) the formation of non-potential magnetic structures with complex polarity separation lines inside the active region, and (3) statistical signatures of canceling bipolar magnetic structures coinciding with flaring activity in the active region. Each of these effects can represent an unstable magnetic configuration acting as an energy source for coronal dissipation and heating.
Vortex and structural dynamics of a flexible cylinder in cross-flow
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)
2014-05-15
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.
Model for Dynamic Self-Assembled Magnetic Surface Structures
M. Belkin; A. Glatz; A. Snezhko; I. S. Aranson
2010-02-02
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.
Electron Dynamics in a Beating Electrostatic Wave Magnetic Null Thruster
Electron dynamics in a beating-electrostatic-wave-powered magnetic null thruster are explored in orderElectron Dynamics in a Beating Electrostatic Wave Magnetic Null Thruster Matthew S. Feldman and Edgar Y. Choueiri Electric Propulsion and Plasma Dynamics Laboratory, Princeton, New Jersey, 08544, USA
All-electrical manipulation of magnetization dynamics in a ferromagnet...
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All-electrical manipulation of magnetization dynamics in a ferromagnet by antiferromagnets with anisotropic spin Hall effects Citation Details In-Document Search This content will...
On the dynamics of magnetic fluids in magnetic resonance imaging
Cantillon-Murphy, Pádraig J
2008-01-01
The hydrodynamics of magnetic fluids, often termed ferrofluids, has been an active area of research since the mid 1960s. However, it is only in the past twenty years that these fluids have begun to be used in magnetic ...
Quasi-two Dimensional Hydrodynamics and Interaction of Vortex Tubes
Zakharov, Vladimir
Quasi-two Dimensional Hydrodynamics and Interaction of Vortex Tubes Vladimir Zakharov 1 but a careful study of the dynamics of the vortex tubes or their systems in a real 3-dimentional nonstationary for description of this type of flow looks very timely. Another motivation is the vortex dynamics
Brownian Dynamics of charged particles in a constant magnetic field
Hou, L J; Piel, A; Shukla, P K
2009-01-01
Numerical algorithms are proposed for simulating the Brownian dynamics of charged particles in an external magnetic field, taking into account the Brownian motion of charged particles, damping effect and the effect of magnetic field self-consistently. Performance of these algorithms is tested in terms of their accuracy and long-time stability by using a three-dimensional Brownian oscillator model with constant magnetic field. Step-by-step recipes for implementing these algorithms are given in detail. It is expected that these algorithms can be directly used to study particle dynamics in various dispersed systems in the presence of a magnetic field, including polymer solutions, colloidal suspensions and, particularly complex (dusty) plasmas. The proposed algorithms can also be used as thermostat in the usual molecular dynamics simulation in the presence of magnetic field.
Voltage-Controlled Magnetic Dynamics in Nanoscale Magnetic Tunnel Junctions
Alzate Vinasco, Juan Guillermo
2014-01-01
Amiri, “Low-Power Nonvolatile Spintronic Memory: STT-RAM andMagnetic Anisotropy in Spintronic Devices," SPIN, vol. 02,I. A. Young, "Benchmarking spintronic logic devices based on
Du, Ruoyang; Robertson, Paul
2014-12-18
—Finite element methods (FEM), Magnetic hysteresis, Magnetic losses, Magnetization, Permanent magnet machines, Permanent magnet motors, Permanent magnet generators. I. INTRODUCTION HE magnetic power losses in ferromagnetic materials have been continuously... made to the original dynamic Jiles-Atherton model in order to make it work correctly for laminations in high frequency permanent magnet synchronous machines (PMSMs), such as BLDC motors. Since the working frequencies of modern BLDC motors...
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
Nori, Franco
of lattices as a driving force is increased. For superconducting systems, experimental work in neutron conductivity. By monitoring the moving vortex lattice, we show that these features coincide with pronounced by elastic theories. Different system parameters produce other phases, including an ordered channel flow
Geometric phases for corotating elliptical vortex patches B. N. Shashikantha)
Shashikanth, Banavara N.
of an infinitely long rectilinear vortex tube of area A whose vorticity distribution is invariant along the lengthGeometric phases for corotating elliptical vortex patches B. N. Shashikantha) Control and Dynamical September 2000 We describe a geometric phase that arises when two elliptical vortex patches co- rotate
X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation
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represents the binary 0 and the other the binary 1. Driven by the consumer's insatiable demand for inexpensive devices that store more data in a smaller area and access it faster...
X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation
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devices that store more data in a smaller area and access it faster while consuming less power, the data storage industry is ever on the lookout for new materials with new...
X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservationBio-Inspired SolarAbout /Two0PhotosPresentationsWorld's largestX-Ray ImagingImaging
X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservationBio-Inspired SolarAbout /Two0PhotosPresentationsWorld's largestX-Ray
X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservationBio-Inspired SolarAbout /Two0PhotosPresentationsWorld's largestX-RayX-Ray Imaging of
X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorkingLos Alamos verifies largest single goldWind PowerX-RayX-Ray
X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorkingLos Alamos verifies largest single goldWind PowerX-RayX-RayX-Ray
X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorkingLos Alamos verifies largest single goldWind PowerX-RayX-RayX-RayX-Ray
X-Ray Imaging of the Dynamic Magnetic Vortex Core Deformation
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorkingLos Alamos verifies largest single goldWind
Dynamics of a dielectric droplet suspended in a magnetic fluid in electric and magnetic fields
Arthur Zakinyan; Elena Tkacheva; Yury Dikansky
2012-03-24
The behavior of a microdrop of dielectric liquid suspended in a magnetic fluid and exposed to the action of electric and magnetic fields is studied experimentally. With increasing electric field, the deformation of droplets into oblate ellipsoid, toroid and curved toroid was observed. At the further increase in the electric field, the bursting of droplets was also revealed. The electrorotation of deformed droplets was observed and investigated. The influence of an additional magnetic field on the droplet dynamics was studied. The main features of the droplet dynamics were interpreted and theoretically examined.
Magnetization dynamics of cobalt grown on graphene
Berger, A. J.; White, S. P.; Adur, R.; Pu, Y.; Hammel, P. C.; Amamou, W.; Kawakami, R. K.
2014-05-07
Ferromagnetic resonance (FMR) spin pumping is a rapidly growing field which has demonstrated promising results in a variety of material systems. This technique utilizes the resonant precession of magnetization in a ferromagnet to inject spin into an adjacent non-magnetic material. Spin pumping into graphene is attractive on account of its exceptional spin transport properties. This article reports on FMR characterization of cobalt grown on chemical vapor deposition graphene and examines the validity of linewidth broadening as an indicator of spin pumping. In comparison to cobalt samples without graphene, direct contact cobalt-on-graphene exhibits increased FMR linewidth—an often used signature of spin pumping. Similar results are obtained in Co/MgO/graphene structures, where a 1?nm MgO layer acts as a tunnel barrier. However, magnetometry, magnetic force microscopy, and Kerr microscopy measurements demonstrate increased magnetic disorder in cobalt grown on graphene, perhaps due to changes in the growth process and an increase in defects. This magnetic disorder may account for the observed linewidth enhancement due to effects such as two-magnon scattering or mosaicity. As such, it is not possible to conclude successful spin injection into graphene from FMR linewidth measurements alone.
Tunable dynamic response of magnetic gels: impact of structural properties and magnetic fields
Mitsusuke Tarama; Peet Cremer; Dmitry Y. Borin; Stefan Odenbach; Hartmut Löwen; Andreas M. Menzel
2014-09-24
Ferrogels and magnetic elastomers feature mechanical properties that can be reversibly tuned from outside through magnetic fields. Here we concentrate on the question how their dynamic response can be adjusted. The influence of three factors on the dynamic behavior is demonstrated using appropriate minimal models: first, the orientational memory imprinted into one class of the materials during their synthesis; second, the structural arrangement of the magnetic particles in the materials; and third, the strength of an external magnetic field. To illustrate the latter point, structural data are extracted from a real experimental sample and analyzed. Understanding how internal structural properties and external influences impact the dominant dynamical properties helps to design materials that optimize the requested behavior.
Disordering transitions in vortex matter: peak effect and phase diagram
Scalettar, Richard T.
Disordering transitions in vortex matter: peak effect and phase diagram C.J. Olson a,*, C- order nature of this transition. In YBCO a rapid increase in Jc as a function of magnetic field vortex phase diagram as a function of magnetic field and temperature. For increasing field or temperature
Microwave magnetic dynamics in highly conducting magnetic nanostructures
Kostylev, M.; Ivanov, E.; Samarin, S. [School of Physics M013, The University of Western Australia, Crawley, WA 6009 (Australia); Ding, J.; Adeyeye, A. O. [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)
2014-05-07
We performed low-noise broadband microstrip ferromagnetic resonance (FMR) measurements of the resonant modes of an array of metallic ferromagnetic nanostripes. In addition to a strong signal of the fundamental mode, we observed up to five weak-amplitude peaks in the field-resolved FMR traces, depending on the frequency. These higher-order absorption peaks have been theoretically identified as due to resonant excitation of odd and even standing spin waves across the direction of confinement in array plane (i.e., across the stripe width). The theory we developed suggests that the odd modes become excited in the spatially uniform microwave field of the FMR setup due to the large conductivity of metals. This promotes excitation of large-amplitude eddy currents in the sample by the incident microwave magnetic field and ultimately results in excitation of these modes. Following this theory, we found that the eddy current contribution is present only for patterned materials and when the microwave magnetic field is incident on one surface of sample surface, as it is in the case of a microstrip FMR.
Fitzpatrick, Richard
magnetic islands. Such islands degrade plasma confinement because heat and particles are able to travelTwo-fluid magnetic island dynamics in slab geometry. II. Islands interacting with resistive walls-fluid magnetic island dynamics in slab geometry: Determination of the island phase velocity Phys. Plasmas 12
Magnetic fields and the dynamics of spiral galaxies
C. L. Dobbs; D. J. Price
2007-10-18
We investigate the dynamics of magnetic fields in spiral galaxies by performing 3D MHD simulations of galactic discs subject to a spiral potential. Recent hydrodynamic simulations have demonstrated the formation of inter-arm spurs as well as spiral arm molecular clouds provided the ISM model includes a cold HI phase. We find that the main effect of adding a magnetic field to these calculations is to inhibit the formation of structure in the disc. However, provided a cold phase is included, spurs and spiral arm clumps are still present if $\\beta \\gtrsim 0.1$ in the cold gas. A caveat to two phase calculations though is that by assuming a uniform initial distribution, $\\beta \\gtrsim 10$ in the warm gas, emphasizing that models with more consistent initial conditions and thermodynamics are required. Our simulations with only warm gas do not show such structure, irrespective of the magnetic field strength. Furthermore, we find that the introduction of a cold HI phase naturally produces the observed degree of disorder in the magnetic field, which is again absent from simulations using only warm gas. Whilst the global magnetic field follows the large scale gas flow, the magnetic field also contains a substantial random component that is produced by the velocity dispersion induced in the cold gas during the passage through a spiral shock. Without any cold gas, the magnetic field in the warm phase remains relatively well ordered apart from becoming compressed in the spiral shocks. Our results provide a natural explanation for the observed high proportions of disordered magnetic field in spiral galaxies and we thus predict that the relative strengths of the random and ordered components of the magnetic field observed in spiral galaxies will depend on the dynamics of spiral shocks.
Influence of Domain Wall Pinning on the Dynamic Behavior of Magnetic...
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on the Dynamic Behavior of Magnetic Vortices Print Soft magnetic, micron-sized thin-film structures with magnetic vortices are intriguing systems that may one day be used in...
Dynamics of skyrmions in chiral magnets: Dynamic phase transitions and equation of motion
Lin, Shi-Zeng, E-mail: szl@lanl.gov; Reichhardt, Charles; Batista, Cristian D.; Saxena, Avadh [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2014-05-07
We study the dynamics of skyrmions in a metallic chiral magnet. First, we show that skyrmions can be created dynamically by destabilizing the ferromagnetic background state through a spin polarized current. We then treat skyrmions as rigid particles and derive the corresponding equation of motion. The dynamics of skyrmions is dominated by the Magnus force, which accounts for the weak pinning of skyrmions observed in experiments. Finally, we discuss the quantum motion of skyrmions.
Fitzpatrick, Richard
because both heat and particles are able to travel radially from one side of an island chain to the otherNonlinear dynamics of feedback modulated magnetic islands in toroidal plasmas Richard Fitzpatrick-induced magnetic responses during nonlinear dynamics of magnetic islands due to resonant magnetic perturbations
NUMERICAL SIMULATION OF VORTEX BREAKDOWN
Prete, Vincenza Del
2011-01-01
irrotational vortex. NRC Con. Aero Rep. LR-378. Hald, O. &vortex breakdown" phenomenon. Aero Dept. , Imperial ColI.
Önder, Asim; Meyers, Johan
2014-07-15
We study the near field of a zero-net-mass-flux (ZNMF) actuated round jet using direct numerical simulations. The Reynolds number of the jet Re{sub D} = 2000 and three ZNMF actuators are used, evenly distributed over a circle, and directed towards the main jet. The actuators are triggered in phase, and have a relatively low momentum coefficient of C{sub ?} = 0.0049 each. We study four different control frequencies with Strouhal numbers ranging from St{sub D} = 0.165 to St{sub D} = 1.32; next to that, also two uncontrolled baseline cases are included in the study. We find that this type of ZNMF actuation leads to strong deformations of the near-field jet region that are very similar to those observed for non-circular jets. At the end of the jet's potential core (x/D = 5), the jet-column cross section is deformed into a hexagram-like geometry that results from strong modifications of the vortex structures. Two mechanisms lead to these modifications, i.e., (i) self-deformation of the jet's primary vortex rings started by distortions in their azimuthal curvature by the actuation, and (ii) production of side jets by the development and subsequent detachment of secondary streamwise vortex pairs. Further downstream (x/D = 10), the jet transforms into a triangular pattern, as the sharp corner regions of the hexagram entrain fluid and spread. We further investigate the global characteristics of the actuated jets. In particular when using the jet preferred frequency, i.e., St{sub D} = 0.33, parameters such as entrainment, centerline decay rate, and mean turbulent kinetic energy are significantly increased. Furthermore, high frequency actuation, i.e., St{sub D} = 1.32, is found to suppress the mechanisms leading to large scale structure growth and turbulent kinetic energy production. The simulations further include a passive scalar equation, and passive scalar mixing is also quantified and visualized.
Vortex precession frequency and its amplitude-dependent shift in cylindrical nanomagnets
Metlov, Konstantin L.
2013-12-14
Frequency of free magnetic vortex precession in circular soft ferromagnetic nano-cylinders (magnetic dots) of various sizes is an important parameter, used in design of spintronic devices (such as spin-torque microwave nano-oscillators) and characterization of magnetic nanostructures. Here, using a recently developed collective-variable approach to non-linear dynamics of magnetic textures in planar nano-magnets, this frequency and its amplitude-dependent shift are computed analytically and plotted for the full range of cylinder geometries. The frequency shift is positive in large planar dots, but becomes negative in smaller and more elongated ones. At certain dot dimensions, a zero frequency shift is realized, which can be important for enhancing frequency stability of magnetic nano-oscillators.
Vortex pinning in super-conductivity as a rate-independent process
Mielke, Alexander
: R the magnetic field perpendicular to the plane. The vortex tube density : R is related to ~H via for this case. The modeling assumption in [Cha00] is now that the vortex tubes will not move if the modulus the conservation of the vortex-tube density which is driven by the current J. The second line contains
Two-fluid magnetic island dynamics in slab geometry: Determination of the island phase velocity
Fitzpatrick, Richard
into helical magnetic islands. Such islands de- grade plasma confinement because heat and particles are ableTwo-fluid magnetic island dynamics in slab geometry: Determination of the island phase velocity R Phys. Plasmas 12, 122308 (2005); 10.1063/1.2141928 Two-fluid magnetic island dynamics in slab geometry
Convectively driven vortex flows in the Sun
J. A. Bonet; I. Marquez; J. Sanchez Almeida; I. Cabello; V. Domingo
2008-09-23
We have discovered small whirlpools in the Sun, with a size similar to the terrestrial hurricanes (<~0.5 Mm). The theory of solar convection predicts them, but they had remained elusive so far. The vortex flows are created at the downdrafts where the plasma returns to the solar interior after cooling down, and we detect them because some magnetic bright points (BPs) follow a logarithmic spiral in their way to be engulfed by a downdraft. Our disk center observations show 0.009 vortexes per Mm^2, with a lifetime of the order of 5 min, and with no preferred sense of rotation. They are not evenly spread out over the surface, but they seem to trace the supergranulation and the mesogranulation. These observed properties are strongly biased by our type of measurement, unable to detect vortexes except when they are engulfing magnetic BPs.
Dynamics of magnetic shells and information loss problem
Bum-Hoon Lee; Wonwoo Lee; Dong-han Yeom
2015-07-17
We investigate dynamics of magnetic thin-shells in three dimensional anti de Sitter background. Because of the magnetic field, an oscillatory solution is possible. This oscillating shell can tunnel to a collapsing shell or a bouncing shell, where both of tunnelings induce an event horizon and a singularity. In the entire path integral, via the oscillating solution, there is a non-zero probability to maintain a trivial causal structure without a singularity. Therefore, due to the path integral, the entire wave function can conserve information. Since an oscillating shell can tunnel after a number of oscillations, in the end, it will allow an infinite number of different branchings to classical histories. This system can be a good model of the effective loss of information, where information is conserved by a solution that is originated from gauge fields.
Dynamic control of spin states in interacting magnetic elements
Jain, Shikha; Novosad, Valentyn
2014-10-07
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.
NUMERICAL SIMULATION OF VORTEX BREAKDOWN
Prete, Vincenza Del
2011-01-01
axis of the tube and is called the vortex core. The basicthe tube plus a perturbation caused by the vortex breakdown.of the tube. Thus the occurrence of the vortex breakdown
The Effects of Wind Tunnel Walls on the Near-field Behavior of a Wingtip Vortex
Hu, Hui
/vortex interaction on helicopter blades can impact performance and cause undesirable noise and vibration. Vortex completely. This method was applied to investigate the effects of the angle of attack of the test wing vortex structures on dynamics of towed vehicles, tail buffeting, and icing arrays. Blade
Magnets & Magnet Condensed Matter Science
McQuade, D. Tyler
Sights from around the Magnet Lab in 2010. On the cover MAGNETS & MAGNET MATERIALS Engineering materials in Mesoporous Silica SBA-15 31 YBCO Pancake Wound Test Coil for 32-T Magnet Development 32 Strong Vortex Pinning from Marine Cyanobacteria 37 Heavy Petroleum Composition 2. Progression of the Boduszynski Model
Crystalline Geometries from Fermionic Vortex Lattice
M. Reza Mohammadi Mozaffar; Ali Mollabashi
2013-08-08
We study charged Dirac fermions on an AdS$_2\\times R^2$ background with a non-zero magnetic field. Under certain boundary conditions, we show that the charged fermion can make the background unstable, resulting in spontaneously formation of a vortex lattice. We observe that an electric field emerges in the back-reacted solution due to the vortex lattice constructed from spin polarized fermions. This electric field may be extended to the UV boundary which leads to a finite charge density. We also discuss corrections to the thermodynamic functions due to the lattice formation.
Gusev, Guennady
2006-01-01
Solid State Nuclear Magnetic Resonance 29 (2006) 5265 Dynamic nuclear polarization and nuclear Nuclear magnetic resonance is detected via the in-plane conductivity of a two-dimensional electron system edge states at the perimeter of the 2DES. Interpretation of the electron-nuclear double resonance
Improved vortex reactor system
Diebold, James P. (Lakewood, CO); Scahill, John W. (Evergreen, CO)
1995-01-01
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.
Houck, Edward D. (Idaho Falls, ID)
1994-01-01
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.
Inelastic electron-vortex-beam scattering
Ruben Van Boxem; Bart Partoens; Jo Verbeeck
2015-03-16
Recent theoretical and experimental developments in the field of electron vortex beam physics have raised questions on what exactly this novelty in the field of electron microscopy (and other fields, such as particle physics) really provides. An important part in the answer to those questions lies in scattering theory. The present investigation explores various aspects of inelastic quantum scattering theory for cylindrically symmetric beams with orbital angular momentum. The model system of Coulomb scattering on a hydrogen atom provides the setting to address various open questions: How is momentum transferred? Do vortex beams selectively excite atoms, and how can one employ vortex beams to detect magnetic transitions? The analytical approach presented here provides answers to these questions. OAM transfer is possible, but not through selective excitation; rather, by pre- and post-selection one can filter out the relevant contributions to a specific signal.
A laboratory plasma experiment for studying magnetic dynamics of accretion discs and jets
Hsu, Scott
A laboratory plasma experiment for studying magnetic dynamics of accretion discs and jets S. C. Hsu into the magnetic dynamics of accretion discs and jets. A high-speed multiple-frame CCD camera reveals images of the formation and helical instability of a collimated plasma, similar to MHD models of disc jets, and also
Electron trapping by a current vortex F. Bentosela, a;b P. Exner, c;d and V.A. Zagrebnov a;b
simpler example involves a Pauli electron interacting with a flux tube modelling a vortex magnetic fieldElectron trapping by a current vortex F. Bentosela, a;b P. Exner, c;d and V.A. Zagrebnov a;b a with the magnetic field due to an electric current forming a localized rotationally symmetric vortex. We show
Dynamic magnetic susceptibility of systems with long-range magnetic order
Vannette, Matthew Dano
2009-05-15
The utility of the TDR as an instrument in the study of magnetically ordered materials has been expanded beyond the simple demonstration purposes. Results of static applied magnetic field dependent measurements of the dynamic magnetic susceptibility, ?, of various ferromagnetic (FM) and antiferromagnetic (AFM) materials showing a range of transition temperatures (1-800 K) are presented. Data was collected primarily with a tunnel diode resonator (TDR) at different radio-frequencies ({approx}10-30 MHz). In the vicinity of TC local moment ferromagnets show a very sharp, narrow peak in ? which is suppressed in amplitude and shifted to higher temperatures as the static bias field is increased. Unexpectedly, critical scaling analysis fails for these data. It is seen that these data are frequency dependent, however there is no simple method whereby measurement frequency can be changed in a controllable fashion. In contrast, itinerant ferromagnets show a broad maximum in ? well below TC which is suppressed and shifts to lower temperatures as the dc bias field is increased. The data on itinerant ferromagnets is fitted to a semi-phenomenological model that suggests the sample response is dominated by the uncompensated minority spins in the conduction band. Concluding remarks suggest possible scenarios to achieve frequency resolved data using the TDR as well as other fields in which the apparatus may be exploited.
ENS'05 Paris, France, 14-16 December 2005 STRUCTURE, MAGNETISM AND DYNAMICS OF
Paris-Sud XI, Université de
the development of recording media and devices with always bigger storage capacities. In this context, magneticENS'05 Paris, France, 14-16 December 2005 STRUCTURE, MAGNETISM AND DYNAMICS OF NANOSTRUCTURED on nanostructured materials including i) magnetic alloyed CoRh nanoparticles that are good candidates to combine
Sliding contacts and the dynamics of magnetic tape transport
Raeymaekers, Bart
2007-01-01
low speed air bearing between a magnetic tape and aair-lubricated foil bearings can be found in magnetic tapebearing pressure and h ( x ) is the spacing between the magnetic
Improved vortex reactor system
Diebold, J.P.; Scahill, J.W.
1995-05-09
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.
Optical vortex driven charge current loop and optomagnetism in fullerenes
Wätzel, Jonas; Schäffer, Alexander; Berakdar, Jamal
2016-01-01
Endohedral molecular magnets, e.g. as realized in fullerenes containing $\\rm DySc_{2}N$, are promising candidates for molecular electronics and quantum information processing. For their functionalization an ultrafast local magnetization control is essential. Using full ab-initio quantum chemistry calculations we predict the emergence of charge current loops in fullerenes with an associated orbital magnetic moment upon irradiation with weak light vortex pulses that transfer orbital angular momentum. The generated current is controllable by the frequency, the vortex topological charge, and the intensity of the light. Numerical and analytical results show that an ultraviolet vortex femtosecond pulse with an intensity $\\sim10^{13}$ W/cm$^2$ generates non-invasively nA unidirectional surface current with an associated magnetic field of hundreds $\\mu$T at the center of the fullerene.
Kasai, Shinya
2009-01-01
for realizing new spintronic devices such as magnetica key technology for future spintronics because it does not
Vortex-Based Aero- and Hydrodynamic Estimation
Hemati, Maziar Sam
2013-01-01
Vortex-Based Aero- and Hydrodynamic Estimation . . . . . .2 Aero- andbenefit from vortex-based aero- and hydrodynamic estimation.
Nonadiabatic Spin Torque Investigated Using Thermally Activated Magnetic Domain Wall Dynamics
Dunin-Borkowski, Rafal E.
Nonadiabatic Spin Torque Investigated Using Thermally Activated Magnetic Domain Wall Dynamics M microscopy, we investigate the thermally activated motion of domain walls (DWs) between two positions properly analyzed, thermally activated processes at tem- peratures even well below the Curie temperature
Formation and dynamics of easy orientation axis in magnetic field on PVCN-F surface
Reznikov, Yuri
of Sciences of Ukraine, 46 Nauki Str., 03-039 Kyiv, Ukraine 2Condensed Phase Dynamics Group, University University, 6 Glushkova Str., 03-680, Kyiv, Ukraine We describe the experiments on a magnetically
Magnetic States in Fe Nanoparticles Imaged by Off-axis Electron Holography Luise Theil Kuhn1*
Dunin-Borkowski, Rafal E.
a procedure that is described elsewhere [1]. In FIG. 1 (d), a magnetic vortex surrounds a flux tube that runs.e. their magnetic configurations may be vortex-like. The critical size for this transition from single domain to vortex behaviour is crucial for determining the net magnetic moments carried by magnetic nanoparticles, i
Current Controller with Defined Dynamic Behavior for an Interior Permanent Magnet
Noé, Reinhold
Current Controller with Defined Dynamic Behavior for an Interior Permanent Magnet Synchronous Motor combustion vehicles already provide. Today's modern HEV and EV mostly include interior permanent magnet]. The required torque, which is the reference variable for these applications, is generated by choosing
PHYSICAL REVIEW B 85, 184301 (2012) Spin-lattice-electron dynamics simulations of magnetic materials
2012-01-01
of experiments on laser-induced demagnetization of iron thin films, and estimate the rates of heat transfer of a magnetic material. They evaluated the total free energies and heat capacities of Fe, Co, and Ni usingPHYSICAL REVIEW B 85, 184301 (2012) Spin-lattice-electron dynamics simulations of magnetic
Low magnetic field dynamic nuclear polarization using a single-coil two-channel probe
Augustine, Mathew P.
Low magnetic field dynamic nuclear polarization using a single-coil two-channel probe Dinh M. Ton and construction of a single-coil, two-channel probe for the detection of low-field magnetic resonance using the electron spins, is tuned to the electron Larmor frequency, 75 MHz at 2.7 mT, and matched to 50 . Low
Detection of Tumors in Dynamic Magnetic Resonance Images using Principal Component Analysis
Detection of Tumors in Dynamic Magnetic Resonance Images using Principal Component Analysis David Alberg Holm (1-2), Thomas BÃ¸vith (2), Cecilia Cappellin (3) (1) Danish Research Centre for Magnetic different tissue classes. For this purpose, two methods were developed and combined. Data Eight mice bearing
Fitzpatrick, Richard
magnetic islands. Such islands degrade plasma confinement because heat and particles are able to travelTwo-fluid magnetic island dynamics in slab geometry. I. Isolated islands Richard Fitzpatrick.1063/1.4863498 Two-fluid magnetic island dynamics in slab geometry: Determination of the island phase velocity Phys
Chaotic magnetization dynamics in single-crystal thin-film structures
Shutyi, A. M., E-mail: shuty@mail.ru; Sementsov, D. I. [Ulyanovsk State University (Russian Federation)
2009-01-15
The nonlinear dynamics of homogeneously precessing magnetization in perpendicularly magnetized single-crystal films has been investigated in a wide range of ac field frequencies on the basis of a numerical solution to the Landau-Lifshitz equation and construction of the spectrum of Lyapunov exponents. The conditions for implementing and specific features of chaotic dynamic modes are revealed for films of three basic crystallographic orientations: (100), (110), and (111). It is shown that chaotic precession modes can be controlled using external magnetic fields. Time analogs of the Poincare section of chaotic mode trajectories are considered.
Magnetic soft x-ray microscopy-imaging fast spin dynamics in magnetic nanostructures
Fischer, Peter; Kim, Dong-Hyun; Mesler, Brooke L.; Chao, Weilun; Sakdinawat, Anne E.; Anderson, Erik H.
2007-01-01
concepts such as spintronics, where in addition to theLogical elements for spintronics, non-volatile magnetic
Kervalishvili, N A
2015-01-01
The results of experimental investigations of the ejection of electrons from gas-discharge nonneutral electron plasma at interaction of vortex structures have been given. The periodical approach of vortex structures causes the ejection of electrons both from the vortex structures themselves and from the adjacent regions of electron sheath to the end cathodes of discharge device. The ejection takes place in the form of short and long pulses following each other. The nature of these pulses and the dynamics of interaction of vortex structures at their approach were studied.
A Non-Abelian Vortex Lattice in Strongly Coupled Systems
Kenny Wong
2013-10-09
The AdS/CFT correspondence predicts that background non-abelian magnetic fields induce instabilities in strongly-coupled systems with non-abelian global symmetries. These instabilities lead to the formation of vortex lattices in which the non-abelian currents "antiscreen" the applied magnetic field. From the bulk perspective, this behaviour can be traced to a well-known instability of Yang-Mills theory. We analyse the phase structure of the instability and comment on aspects of the vortex lattice.
Nonlinear dynamics of large amplitude modes in a magnetized plasma
Brodin, G.; Stenflo, L.
2014-12-15
We derive two equations describing the coupling between electromagnetic and electrostatic oscillations in one-dimensional geometry in a magnetized cold and non-relativistic plasma. The nonlinear interaction between the wave modes is studied numerically. The effects of the external magnetic field strength and the initial electromagnetic polarization are of particular interest here. New results can, thus, be identified.
Optical gyrotropy as a test for dynamic chiral magnetic effect of Weyl semimetals
Pallab Goswami; Girish Sharma; Sumanta Tewari
2015-10-06
Recent angle resolved photoemission spectroscopy measurements have identified an inversion symmetry breaking Weyl semimetal phase in TaAs and NbAs. In an inversion symmetry breaking Weyl semimetal the left and the right handed Weyl points can occur at different energies and the energy mismatch between the Weyl points of opposite chirality is known as the chiral chemical potential. In the presence of the chiral chemical potential, the nontrivial Berry curvature of the Weyl fermions gives rise to the \\emph{dynamic} chiral magnetic effect. This describes how a time dependent magnetic field leads to an electrical current along the applied field direction, which is also proportional to the field strength. We derive a general formula for the dynamic chiral magnetic conductivity of the inversion symmetry breaking Weyl semimetal. We show that the measurement of the natural optical activity or rotary power provides a direct confirmation of the existence of the dynamic chiral magnetic effect in inversion symmetry breaking Weyl semimetals.
Magnetic and electric contributions to the energy loss in a dynamical QCD medium
Magdalena Djordjevic
2011-05-21
The computation of radiative energy loss in a finite size QCD medium with dynamical constituents is a key ingredient for obtaining reliable predictions for jet quenching in ultra-relativistic heavy ion collisions. It was previously shown that energy loss in dynamical QCD medium is significantly higher compared to static QCD medium. To understand this difference, we here analyze magnetic and electric contributions to energy loss in dynamical QCD medium. We find that the significantly higher energy loss in the dynamical case is entirely due to appearance of magnetic contribution in the dynamical medium. While for asymptotically high energies, the energy loss in static and dynamical medium approach the same value, we find that the physical origin of the energy loss in these two cases is different.
Regular and chaotic dynamics of a chain of magnetic dipoles with moments of inertia
Shutyi, A. M. [Ulyanovsk State University (Russian Federation)], E-mail: shuty@mail.ru
2009-05-15
The nonlinear dynamic modes of a chain of coupled spherical bodies having dipole magnetic moments that are excited by a homogeneous ac magnetic field are studied using numerical analysis. Bifurcation diagrams are constructed and used to find conditions for the presence of several types of regular, chaotic, and quasi-periodic oscillations. The effect of the coupling of dipoles on the excited dynamics of the system is revealed. The specific features of the Poincare time sections are considered for the cases of synchronous chaos with antiphase synchronization and asynchronous chaos. The spectrum of Lyapunov exponents is calculated for the dynamic modes of an individual dipole.
Magnetic Fields are not ignorable in the dynamics of disks
E. Battaner; E. Florido; A. Guijarro
2000-09-25
Magnetic fields are considered to be dominant when $\\epsilon_{B}\\geq\\epsilon_{K}$, being $\\epsilon_{B}=B^{2}/8\\pi$ the magnetic energy density and $\\epsilon_{K}=1/2 \\rho\\theta^{2}$ the rotation energy density, for a conventional moderate B= 1 $\\mu$G. They are considered to be negligible when $\\epsilon_{B}<\\epsilon_{K}$ for $B\\sim 10 \\mu$G. With no assumption and no theoretical calculation, we show that magnetic fields cannot be ignored in the outer parts of a galaxy like the Milky Way and in the whole disk of a dwarf galaxy.
Large vortex state in ferromagnetic disks
Metlov, Konstantin L
2013-01-01
Magnetic vortices in soft ferromagnetic nano-disks have been extensively studied for at least several decades both for their fundamental (as a "live" macroscopic realization of a field theory model of an elementary particle) as well as applied value for high-speed high-density power-independent information storage. Here it is shown that there is another vortex state in nano-scale ferromagnetic disks of several exchange lengths in size. The energy of this large vortex state is computed numerically (within the framework of Magnetism@home distributed computing project) and its stability is studied analytically, which allows to plot it on magnetic phase diagram. It is the ground state of cylinders of certain sizes and is metastable in a wider set of geometries. Large vortices exist on par with classical ones, while being separated by an energy barrier, controllable by tuning the geometry and material of ferromagnetic disk. This state can be an excellent candidate for magnetic information storage not only because ...
Rahtika, I Putu Gede Sopan
1998-01-01
This thesis is a report on the research and Micrographics. development to design a test rig for the identification of the dynamic coefficients of a radial magnetic bearing. The test rig development is intended for dynamic coefficient observation...
Strings, vortex rings, and modes of instability
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Gubser, Steven S.; Nayar, Revant; Parikh, Sarthak
2015-03-01
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
Vortex-Based Aero- and Hydrodynamic Estimation
Hemati, Maziar Sam
2013-01-01
1. The strength of a vortex tube is uniform along the tube.3. The strength of a vortex tube is invariant in time. Theof Vortex Ring Formation at the Edge of a Circular Tube. ”
-STABILITY AND VORTEX MOTION IN TYPE II SUPERCONDUCTORS
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
High Reynolds Number Vortices with Magnetic Field in NonAxisymmetric Strain
Bajer, Konrad
of coaxial vortex and magnetic flux tubes supported by nonaxisymmetric uniaxial strain. Two different the radius of the vortex and we call such a tube thin. In section 4 we consider a thick tube (Pm ø 1) whose radius is much larger than that of the vortex tube which is now approximated by a line vortex. The value
Liquid Vortex Shielding for Fusion Energy Applications
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)
2005-05-15
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.
Magneto-Vortex Dynamo Model in Solar convection zone
Sergey V. Ershkov
2011-01-06
Here is presented a new magneto-vortex dynamo model for modeling & predicting of a processes in Solar plasma convection zone. Solar convection zone is located above the level r > 0,6-0,7 R, where R is a Solar radius. A key feature of such a model is that equation of Solar plasma motion as well as equation of magnetic fields evolution - are reduced to Helmholtz's vortex equation, which is up-graded in according with alpha-effect (Coriolis force forms an additional vorticity field or magnetic field due to Sun's differential rotation). Such an additional vorticity or magnetic field are proved to be concentrated at the proper belt in Solar convection zone under the influence of Coriolis force (at the middle latitudes of the Sun in respect to equator). Besides, such an an additional vorticity & magnetic fields are to be the basic sources of well-known phenomena "Maunder's butterfly" diagram.
Tassis, Konstantinos; Willacy, Karen; Yorke, Harold W.; Turner, Neal J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
2012-07-01
We combine dynamical and non-equilibrium chemical modeling of evolving prestellar molecular cloud cores and investigate the evolution of molecular abundances in the contracting core. We model both magnetic cores, with varying degrees of initial magnetic support, and non-magnetic cores, with varying collapse delay times. We explore, through a parameter study, the competing effects of various model parameters in the evolving molecular abundances, including the elemental C/O ratio, the temperature, and the cosmic-ray ionization rate. We find that different models show their largest quantitative differences at the center of the core, whereas the outer layers, which evolve slower, have abundances which are severely degenerate among different dynamical models. There is a large range of possible abundance values for different models at a fixed evolutionary stage (central density), which demonstrates the large potential of chemical differentiation in prestellar cores. However, degeneracies among different models, compounded with uncertainties induced by other model parameters, make it difficult to discriminate among dynamical models. To address these difficulties, we identify abundance ratios between particular molecules, the measurement of which would have maximal potential for discrimination among the different models examined here. In particular, we find that the ratios between NH{sub 3} and CO, NH{sub 2} and CO, and NH{sub 3} and HCO{sup +} are sensitive to the evolutionary timescale, and that the ratio between HCN and OH is sensitive to the C/O ratio. Finally, we demonstrate that measurements of the central deviation (central depletion or enhancement) of abundances of certain molecules are good indicators of the dynamics of the core.
Dynamics of Mesoscale Magnetic Field in Diffusive Shock Acceleration
P. H. Diamond; M. A. Malkov
2006-05-15
We present a theory for the generation of mesoscale ($kr_{g}\\ll 1$, where $r_{g}$ is the cosmic ray gyroradius) magnetic fields during diffusive shock acceleration. The decay or modulational instability of resonantly excited Alfven waves scattering off ambient density perturbations in the shock environment naturally generates larger scale fields. For a broad spectrum of perturbations, the physical mechanism of energy transfer is random refraction, represented by diffusion of Alfven wave packet in $k-$space. The scattering field can be produced directly by the decay instability or by the Drury instability, a hydrodynamic instability driven by the cosmic ray pressure gradient. This process is of interest to acceleration since it generates waves of longer wavelength, and so enables the confinement and acceleration of higher energy particles. This process also limits the intensity of resonantly generated turbulent magnetic field on $r_{g}$ scales.
Vortex lattice for a holographic superconductor
Kengo Maeda; Makoto Natsuume; Takashi Okamura
2009-12-17
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.
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
Proton radiography of dynamic electric and magnetic fields in laser-produced high-energy measurements of the electric E and magnetic B fields produced in laser-foil interactions and during, and dissipation of self-generated electric E and magnetic B fields by inter- actions of laser light with matter1
Eisenbach, Markus; Perera, Meewanage Dilina N; Landau, David P; Nicholson, Don M; Yin, Junqi; Brown, Greg
2015-01-01
We present a unified approach to describe the combined behavior of the atomic and magnetic degrees of freedom in magnetic materials. Using Monte Carlo simulations directly combined with first principles the Curie temperature can be obtained ab initio in good agreement with experimental values. The large scale constrained first principles calculations have been used to construct effective potentials for both the atomic and magnetic degrees of freedom that allow the unified study of influence of phonon-magnon coupling on the thermodynamics and dynamics of magnetic systems. The MC calculations predict the specific heat of iron in near perfect agreement with experimental results from 300K to above Tc and allow the identification of the importance of the magnon-phonon interaction at the phase-transition. Further Molecular Dynamics and Spin Dynamics calculations elucidate the dynamics of this coupling and open the potential for quantitative and predictive descriptions of dynamic structure factors in magnetic materials using first principles derived simulations.
Studies of Optically Induced Magnetization Dynamics in Colloidal Iron Oxide Nanocrystals
Hsia, Chih-Hao
2011-10-21
the SLR rates of Fe3O4 nanocrystals with various sizes. Higher efficiency of SLR at the surface may be due to the stronger spin-orbit coupling at the surface relative to the interior region. In addition to magnetization dynamics studies, the effect...
DYNAMICS OF LIQUID METAL JETS PENETRATING A STRONG MAGNETIC FIELD IN HIGH-POWER COLLIDERS
Harilal, S. S.
DYNAMICS OF LIQUID METAL JETS PENETRATING A STRONG MAGNETIC FIELD IN HIGH-POWER COLLIDERS A. Liquid metal jets (pulsed or continuous) are proposed as potential target candidates. Such a proposal poses two critical problems: penetration of a free liquid jet inside the required strong inhomogeneous
Electron dynamics in parallel electric and magnetic fields
Christian Bracher; Tobias Kramer; John B. Delos
2005-10-13
We examine the spatial distribution of electrons generated by a fixed energy point source in uniform, parallel electric and magnetic fields. This problem is simple enough to permit analytic quantum and semiclassical solution, and it harbors a rich set of features which find their interpretation in the unusual and interesting properties of the classical motion of the electrons: For instance, the number of interfering trajectories can be adjusted in this system, and the turning surfaces of classical motion contain a complex array of singularities. We perform a comprehensive analysis of both the semiclassical approximation and the quantum solution, and we make predictions that should serve as a guide for future photodetachment experiments.
Static and Dynamical Phyllotaxis in a Magnetic Cactus
Cristiano Nisoli; Nathaniel Gabor; Paul E. Lammert; Vincent H. Crespi
2009-04-08
While the statics of many simple physical systems reproduce the striking number-theoretical patterns found in the phyllotaxis of living beings, their dynamics reveal unusual excitations: multiple classical rotons and a large family of interconverting topological solitons. As we introduce those, we also demonstrate experimentally for the first time Levitov's celebrated model for phyllotaxis. Applications at different scales and in different areas of physics are proposed and discussed.
Dynamics of Ion Temperature Gradient Turbulence and Transport with a Static Magnetic Island
Izacard, Olivier; James, Spencer D; Brennan, Dylan P
2015-01-01
The quantification of the interaction mechanism between large-scale magnetohydrodynamics instabilities and small-scale drift-wave microturbulence is essential for predicting and optimizing the performance of magnetic confinement based fusion energy experiments. We report progress on understanding these interactions using both analytic theory and numerical simulation, with BOUT++ [B. Dudson et al., Comput. Phys. Comm. 180, 1467 (2009)] used to evolve simple five-field fluid models in a sheared slab geometry. This work focuses upon understanding the dynamics of the ion temperature gradient instability in the presence of a background static magnetic island in a weakly electromagnetic two-dimensional five-field model as key parameters such as ion temperature gradient, magnetic gradients and static magnetic island size are varied. The simulation results are then used to calculate the effective turbulent transport coefficient (i.e. resistivity) that is compared against classical coefficient. As part of this work, t...
Thermal effects on transverse domain wall dynamics in magnetic nanowires
Leliaert, J.; Van de Wiele, B.; Vandermeulen, J.; Coene, A.; Dupré, L.; Vansteenkiste, A.; Waeyenberge, B. Van; Laurson, L.; Durin, G.
2015-05-18
Magnetic domain walls are proposed as data carriers in future spintronic devices, whose reliability depends on a complete understanding of the domain wall motion. Applications based on an accurate positioning of domain walls are inevitably influenced by thermal fluctuations. In this letter, we present a micromagnetic study of the thermal effects on this motion. As spin-polarized currents are the most used driving mechanism for domain walls, we have included this in our analysis. Our results show that at finite temperatures, the domain wall velocity has a drift and diffusion component, which are in excellent agreement with the theoretical values obtained from a generalized 1D model. The drift and diffusion component are independent of each other in perfect nanowires, and the mean square displacement scales linearly with time and temperature.
Lagrangian analysis of fluid transport in empirical vortex ring flows Shawn C. Shadden
Marsden, Jerrold
Lagrangian analysis of fluid transport in empirical vortex ring flows Shawn C. Shadden Control and Dynamical Systems, California Institute of Technology, Pasadena, California 91125 John O. Dabiri Graduate Aeronautical Laboratories and Bioengineering, California Institute of Technology, Pasadena, California 91125
Dynamic Switching of the Spin Circulation in Tapered Magnetic Nanodisks
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would like submit theCovalentLaboratory |Sectorfor $1.14 Per1-ENuclearDynamic Switching of
WAVE-VORTEX INTERACTIONS IN THE ATMOSPHERE, AND CLIMATE
Al Hanbali, Ahmad
WAVE-VORTEX INTERACTIONS IN THE ATMOSPHERE, AND CLIMATE PREDICTION Onno Bokhove Numerical Analysis, The Netherlands o.bokhove@math.utwente.nl Abstract Can we construct an accurate atmospheric climate model parcel dynamics, linear modes, balan- ced models, gravity waves, weather and climate prediction
Fuentes, Oscar Velasco
2015-01-01
We study the motion of a single helical vortex in an unbounded, inviscid, incompressible fluid. The vortex is an infinite tube whose centerline is a helix and whose cross section is a circle of small radius (compared to the radius of curvature) where the vorticity is uniform and parallel to the centerline. Ever since Joukowsky (1912) deduced that this vortex translates and rotates steadily without change of form, numerous attempts have been made to compute these self-induced velocities. Here we use Hardin's (1982) solution for the velocity field to find new expressions for the vortex's linear and angular velocities. Our results, verified by numerically computing the Helmholtz integral and the Rosenhead-Moore approximation to the Biot-Savart law, are more accurate than previous results over the whole range of values of the vortex pitch and cross-section. We then use the new formulas to study the advection of passive particles near the vortex; we find that the vortex's motion and capacity to transport fluid dep...
Low NOx Advanced Vortex Combustor
Edmonds, R.G. (Ramgen Power Systems, Inc., Bellevue, WA); Williams, J.T. (Ramgen Power Systems, Inc., Bellevue, WA); Steele, R.C. (EPRI); Straub, D.L.; Casleton, K.H.; Bining, Avtar (California Energy Commission, Sacramento, CA)
2008-05-01
A lean-premixed advanced vortex combustor (AVC) has been developed and tested. The natural gas fueled AVC was tested at the U.S. Department of Energy’s National Energy Technology Laboratory in Morgantown, WV. All testing was performed at elevated pressures and inlet temperatures and at lean fuel-air ratios representative of industrial gas turbines. The improved AVC design exhibited simultaneous NOx /CO/unburned hydrocarbon (UHC) emissions of 4/4/0 ppmv (all emissions corrected to 15% O2 dry). The design also achieved less than 3 ppmv NOx with combustion efficiencies in excess of 99.5%. The design demonstrated marked acoustic dynamic stability over a wide range of operating conditions, which potentially makes this approach significantly more attractive than other lean-premixed combustion approaches. In addition, the measured 1.75% pressure drop is significantly lower than conventional gas turbine combustors, which could translate into an overall gas turbine cycle efficiency improvement. The relatively high velocities and low pressure drop achievable with this technology make the AVC approach an attractive alternative for syngas fuel applications.
Crystalline Scaling Geometries from Vortex Lattices
Ning Bao; Sarah Harrison
2013-06-25
We study magnetic geometries with Lifshitz and/or hyperscaling violation exponents (both with a hard wall cutoff in the IR and a smooth black brane horizon) which have a complex scalar field which couples to the magnetic field. The complex scalar is unstable to the production of a vortex lattice in the IR. The lattice is a normalizable mode which is relevant (i.e. grows into the IR.) When one considers linearized backreaction of the lattice on the metric and gauge field, the metric forms a crystalline structure. We analyze the scaling of the free energy, thermodynamic entropy, and entanglement in the lattice phase and find that in the smeared limit, the leading order correction to thermodynamic properties due to the lattice has the scaling behavior of a theory with a hyperscaling violation exponent between 0 and 1, indicating a flow to an effectively lower-dimensional theory in the deep IR.
Magnetic Fields Boosted by Gluon Vortices in Color Superconductivity
Efrain J. Ferrer; Vivian de la Incera
2006-08-28
We investigate the effects of an external magnetic field in the gluon dynamics of a color superconductor with three massless quark flavors. In the framework of gluon mean-field theory at asymptotic densities, we show that the long-range component $\\widetilde{H}$ of the external magnetic field that penetrates the CFL phase produces an instability when its strength becomes larger than the Meissner mass of the charged gluons. As a consequence, the magnetic field causes the formation of a vortex state characterized by the condensation of charged gluons and the creation of magnetic flux tubes. Inside the flux tubes the magnetic field is stronger than the applied one. This antiscreening effect is connected to the anomalous magnetic moment of the gluon field. We suggest how this same mechanism could serve to remove the chromomagnetic instabilities existing in gapless color superconductivity.
GravitoMagnetic force in modified Newtonian dynamics
Exirifard, Qasem
2013-08-01
We introduce the Gauge Vector-Tensor (GVT) theory by extending the AQUAL's approach to the GravitoElectroMagnetism (GEM) approximation of gravity. GVT is a generally covariant theory of gravity composed of a pseudo Riemannian metric and two U(1) gauge connections that reproduces MOND in the limit of very weak gravitational fields while remains consistent with the Einstein-Hilbert gravity in the limit of strong and Newtonian gravitational fields. GVT also provides a simple framework to study the GEM approximation to gravity. We illustrate that the gravitomagnetic force at the edge of a galaxy can be in accord with either GVT or ?CDM but not both. We also study the physics of the GVT theory around the gravitational saddle point of the Sun and Jupiter system. We notice that the conclusive refusal of the GVT theory demands measuring either both of the gravitoelectric and gravitomagnetic fields inside the Sun-Jupiter MOND window, or the gravitoelectric field inside two different solar GVT MOND windows. The GVT theory, however, will be favored by observing an anomaly in the gravitoelectric field inside a single MOND window.
Dynamical properties of three terminal magnetic tunnel junctions: Spintronics meets spin-orbitronics
Tomasello, R.; Carpentieri, M.; Finocchio, G.
2013-12-16
This Letter introduces a micromagnetic model able to characterize the magnetization dynamics in three terminal magnetic tunnel junctions, where the effects of spin-transfer torque and spin-orbit torque are taken into account. Our results predict that the possibility to separate electrically those two torque sources is very promising from a technological point of view for both next generation of nanoscale spintronic oscillators and microwave detectors. A scalable synchronization scheme based on the parallel connection of those three terminal devices is also proposed.
Elementary Vortex Processes in Thermal Superfluid Turbulence
Kivotides, Demosthenes; Wilkin, S. Louise
2009-01-01
a complex system of vortex tubes has only (a vigorouslyIn this context, the vortex tube model (VTM) of Kivotidesstraight normal ?uid vortex tube, suggested an explicit
An Empirical Relation Between The Large-Scale Magnetic Field And The Dynamical Mass In Galaxies
Tabatabaei, F S; Knapen, J H; Beckman, J E; Koribalski, B; Elmegreen, B G
2015-01-01
The origin and evolution of cosmic magnetic fields as well as the influence of the magnetic fields on the evolution of galaxies are unknown. Though not without challenges, the dynamo theory can explain the large-scale coherent magnetic fields which govern galaxies, but observational evidence for the theory is so far very scarce. Putting together the available data of non-interacting, non-cluster galaxies with known large-scale magnetic fields, we find a tight correlation between the integrated polarized flux density and the rotation speed, v(rot), of galaxies. This leads to an almost linear correlation between the large-scale magnetic field B and v(rot), assuming that the number of cosmic ray electrons is proportional to the star formation rate. This correlation cannot be attributed to an active linear dynamo processes, as no correlation holds with shear or angular speed. It indicates instead a coupling between the large-scale magnetic field and the dynamical mass of the galaxies, B~M(dyn)^{0.2-0.3}. Hence, f...
Wave–vortex interactions in the nonlinear Schrödinger equation
Guo, Yuan Bühler, Oliver
2014-02-15
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.
Alexander J. Silenko
2007-10-02
A buildup of the vertical polarization in the resonant electric dipole moment (EDM) experiment [Y. F. Orlov, W. M. Morse, and Y. K. Semertzidis, Phys. Rev. Lett. 96, 214802 (2006)] is affected by a horizontal electric field in the particle rest frame oscillating at a resonant frequency. This field is defined by the Lorentz transformation of an oscillating longitudinal electric field and a uniform vertical magnetic one. The effect of a longitudinal electric field is significant, while the contribution from a magnetic field caused by forced coherent longitudinal oscillations of particles is dominant. The effect of electric field on the spin dynamics was not taken into account in previous calculations. This effect is considerable and leads to decreasing the EDM effect for the deuteron and increasing it for the proton. The formula for resonance strengths in the EDM experiment has been derived. The spin dynamics has been calculated.
Magnetization dynamics: path-integral formalism for the stochastic Landau-Lifshitz-Gilbert equation
Camille Aron; Daniel G. Barci; Leticia F. Cugliandolo; Zochil Gonzalez Arenas; Gustavo S. Lozano
2014-12-31
We construct a path-integral representation of the generating functional for the dissipative dynamics of a classical magnetic moment as described by the stochastic generalization of the Landau-Lifshitz-Gilbert equation proposed by Brown, with the possible addition of spin-torque terms. In the process of constructing this functional in the Cartesian coordinate system, we critically revisit this stochastic equation. We present it in a form that accommodates for any discretization scheme thanks to the inclusion of a drift term. The generalized equation ensures the conservation of the magnetization modulus and the approach to the Gibbs-Boltzmann equilibrium in the absence of non-potential and time-dependent forces. The drift term vanishes only if the mid-point Stratonovich prescription is used. We next reset the problem in the more natural spherical coordinate system. We show that the noise transforms non-trivially to spherical coordinates acquiring a non-vanishing mean value in this coordinate system, a fact that has been often overlooked in the literature. We next construct the generating functional formalism in this system of coordinates for any discretization prescription. The functional formalism in Cartesian or spherical coordinates should serve as a starting point to study different aspects of the out-of-equilibrium dynamics of magnets. Extensions to colored noise, micro-magnetism and disordered problems are straightforward.
Deep sub-nanosecond reversal of vortex cores confined in a spin-wave potential well
Dong, Xinwei; Wang, Zhenyu; Wang, Ruifang, E-mail: wangrf@xmu.edu.cn [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen 361005 (China)
2014-03-17
A spin-wave potential well is created in a permalloy nanodisk by setting up a cylindrical cavity in the center of the sample. We then apply a single-harmonic external magnetic field perpendicular to the disk plane to switch the vortex polarity of the sample. Our micromagnetic numerical studies establish that the effective spin-wave confinement by the potential well leads to much stronger magnetization oscillation in the sample. Therefore, the vortex core can be reversed well below 200 ps and over a wide range of field frequency. Our findings present an additional efficient means for ultrafast switching of magnetic vortices.
Bettarini, Lapo [Katholieke Universiteit Leuven, Centrum voor Plasma Astrofysica, Celestijnenlaan 200B, B-3001 Leuven (Belgium); Dipartimento di Astronomia e Scienza dello Spazio, Universita degli Studi di Firenze, Largo E. Fermi, 2, I-50125 Firenze (Italy); Landi, Simone [Dipartimento di Astronomia e Scienza dello Spazio, Universita degli Studi di Firenze, Largo E. Fermi, 2, I-50125 Firenze (Italy); Velli, Marco [Dipartimento di Astronomia e Scienza dello Spazio, Universita degli Studi di Firenze, Largo E. Fermi, 2, I-50125 Firenze (Italy); Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109 (United States); Londrillo, Pasquale [INAF Osservatorio Astronomico di Bologna, via C. Ranzani 1, I-40127 Bologna (Italy)
2009-06-15
The problem of three-dimensional combined magnetic and velocity shear driven instabilities of a compressible magnetized jet modeled as a plane neutral/current double vortex sheet in the framework of the resistive magnetohydrodynamics is addressed. The resulting dynamics given by the stream+current sheet interaction is analyzed and the effects of a variable geometry of the basic fields are considered. Depending on the basic asymptotic magnetic field configuration, a selection rule of the linear instability modes can be obtained. Hence, the system follows a two-stage path developing either through a fully three-dimensional dynamics with a rapid evolution of kink modes leading to a final turbulent state, or rather through a driving two-dimensional instability pattern that develops on parallel planes on which a reconnection+coalescence process takes place.
IEEE TRANS. PLASMA SCIENCE, VOL. XX, NO. X, DECEMBER 201X 1 Dust dynamics in magnetic fusion plasmas
Princeton Plasma Physics Laboratory
IEEE TRANS. PLASMA SCIENCE, VOL. XX, NO. X, DECEMBER 201X 1 Dust dynamics in magnetic fusion plasmas: generation, transport, destruction and applications Zhehui Wang, Member, IEEE, Robert Lunsford
Luo, Xiaoyu
Effect of tube spacing on the vortex shedding characteristics of laminar flow past an inline tube the tubes. Complex flow dynamic phenomena such as reattachment of shear layers, in- duced separation, vortex Accepted 27 October 2008 Available online 14 November 2008 a b s t r a c t The effect of tube spacing
Tassis, Konstantinos; Willacy, Karen; Yorke, Harold W.; Turner, Neal J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
2012-07-20
We study the effect that non-equilibrium chemistry in dynamical models of collapsing molecular cloud cores has on measurements of the magnetic field in these cores, the degree of ionization, and the mean molecular weight of ions. We find that OH and CN, usually used in Zeeman observations of the line-of-sight magnetic field, have an abundance that decreases toward the center of the core much faster than the density increases. As a result, Zeeman observations tend to sample the outer layers of the core and consistently underestimate the core magnetic field. The degree of ionization follows a complicated dependence on the number density at central densities up to 10{sup 5} cm{sup -3} for magnetic models and 10{sup 6} cm{sup -3} in non-magnetic models. At higher central densities, the scaling approaches a power law with a slope of -0.6 and a normalization which depends on the cosmic-ray ionization rate {zeta} and the temperature T as ({zeta}T){sup 1/2}. The mean molecular weight of ions is systematically lower than the usually assumed value of 20-30, and, at high densities, approaches a value of 3 due to the asymptotic dominance of the H{sup +}{sub 3} ion. This significantly lower value implies that ambipolar diffusion operates faster.
Klein, Avraham; Aleiner, Igor L.; Agam, Oded
2014-07-15
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.
A vortex tube is a device of a simple structure with no moving parts that can be used to separate of the energy separation in the vortex tube. Recent rapid development in computational fluid dynamics is providing a powerful tool to investigate the complex flow in the vortex tube. However various issues
Gravity waves from vortex dipoles and jets
Wang, Shuguang
2009-05-15
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...
Fluid Dynamics IB Dr Natalia Berloff
are said to form the boundary of a vortex tube. We say that `stretching amplfies vorticity'. It is also as if they were material lines. Or, vortex tubes rotate and stretch just like the material line elementsFluid Dynamics IB Dr Natalia Berloff §2.6 Vorticity Definition: Vorticity = × u. A vortex line
Abdoli-Arani, A.; Jazi, B. [Department of Photonics, Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); Shokri, B. [Physics Department and Laser-Plasma Research Institute, G. C. Shahid Beheshti University, Tehran (Iran, Islamic Republic of)
2013-02-15
The dynamics and energy gain of an electron in the field of a transverse magnetic wave propagating inside an elliptical degenerate plasma waveguide is analytically investigated by finding the field components of the TM{sub mr} mode in this waveguide. Besides, by solving the relativistic momentum and energy equations the deflection angle and the acceleration gradient of the electron in the waveguide are obtained. Furthermore, the field components of the hybrid mode and the transferred power in the presence of the magnetic field in this waveguide are found. Also by applying the boundary conditions at the plasma-conductor interface, we calculate the dispersion relation. It is shown that the cutoff frequency of this mode is dependent on the plasma density but independent of the magnetic field. Then, a single-electron model for numerical calculations of the electron deflection angle and acceleration gradient inside the magnetized plasma-filled elliptical waveguide is generally presented to be used as a cascading process for the acceleration purposes.
On the electron dynamics during island coalescence in asymmetric magnetic reconnection
Cazzola, Emanuele; Markidis, Stefano; Goldman, Martin V; Newman, David L; Lapenta, Giovanni
2015-01-01
We present an analysis of the electron dynamics during rapid island merging in asymmetric magnetic reconnection. We consider a doubly periodic system with two asymmetric transitions. The upper layer is an asymmetric Harris sheet initially perturbed to promote a single reconnection site. The lower layer is a tangential discontinuity that promotes the formation of many X-points, separated by rapidly merging islands. Across both layers the magnetic field and the density have a strong jump, but the pressure is held constant. Our analysis focuses on the consequences of electron energization during island coalescence. We focus first on the parallel and perpendicular components of the electron temperature to establish the presence of possible anisotropies and non-gyrotropies. Thanks to the direct comparison between the two different layers simulated, we can distinguish three main types of behavior characteristic of three different regions of interest. The first type represents the regions where traditional asymmetri...
Non-linear dynamics of Kelvin-Helmholtz unstable magnetized jets three-dimensional effects
Keppens, R
1999-01-01
A numerical study of the Kelvin-Helmholtz instability in compressible magnetohydrodynamics is presented. The three-dimensional simulations consider shear flow in a cylindrical jet configuration, embedded in a uniform magnetic field directed along the jet axis. The growth of linear perturbations at specified poloidal and axial mode numbers demonstrate intricate non-linear coupling effects. The physical mechanims leading to induced secondary Kelvin-Helmholtz instabilities at higher mode numbers are identified. The initially weak magnetic field becomes locally dominant in the non-linear dynamics before and during saturation. Thereby, it controls the jet deformation and eventual breakup. The results are obtained using the Versatile Advection Code [G. Toth, Astrophys. Lett. Comm. 34, 245 (1996)], a software package designed to solve general systems of conservation laws. An independent calculation of the same Kelvin-Helmholtz unstable jet configuration using a three-dimensional pseudo-spectral code gives important ...
Dissipative soliton dynamics in a discrete magnetic nano-dot chain
Lee, Kyeong-Dong; You, Chun-Yeol; Song, Hyon-Seok; Shin, Sung-Chul; Park, Byong-Guk
2014-02-03
Soliton dynamics is studied in a discrete magnetic nano-dot chain by means of micromagnetic simulations together with an analytic model equation. A soliton under a dissipative system is driven by an applied field. The field-driven dissipative soliton enhances its mobility nonlinearly, as the characteristic frequency and the intrinsic Gilbert damping decrease. During the propagation, the soliton emits spin waves which act as an extrinsic damping channel. The characteristic frequency, the maximum velocity, and the localization length of the soliton are found to be proportional to the threshold field, the threshold velocity, and the initial mobility, respectively.
Vecchio, A.; Meduri, D.; Carbone, V. [Dipartimento di Fisica, Universita della Calabria, 87036 Rende (Italy); Laurenza, M.; Storini, M., E-mail: vecchio@fis.unical.it [INAF/IFSI-Roma, Via del Fosso del Cavaliere 100, 00133 Roma (Italy)
2012-04-10
The spatio-temporal dynamics of the solar magnetic field has been investigated by using NSO/Kitt Peak magnetic synoptic maps covering the period 1976 August-2003 September. The field radial component, for each heliographic latitude, has been decomposed in intrinsic mode functions through the Empirical Mode Decomposition in order to investigate the time evolution of the various characteristic oscillating modes at different latitudes. The same technique has also been applied on synoptic maps of the meridional and east-west components, which were derived from the observed line-of-sight projection of the field by using the differential rotation. Results obtained for the {approx}22 yr cycle, related to the polarity inversions of the large-scale dipolar field, show an antisymmetric behavior with respect to the equator in all the field components and a marked poleward flux migration in the radial and meridional components (from about -35 Degree-Sign and +35 Degree-Sign in the southern and northern hemispheres, respectively). The quasi-biennial oscillations (QBOs) are also identified as a fundamental timescale of variability of the magnetic field and associated with poleward magnetic flux migration from low latitudes around the maximum and descending phase of the solar cycle. Moreover, signs of an equatorward drift, at a {approx}2 yr rate, seem to appear in the radial and toroidal components. Hence, the QBO patterns suggest a link to a dynamo action. Finally, the high-frequency component of the magnetic field, at timescales less than 1 yr, provides the most energetic contribution and it is associated with the outbreaks of the bipolar regions on the solar surface.
Well-observed dynamics of flaring and peripheral coronal magnetic loops during an M-class limb flare
Shen, Jinhua; Zhou, Tuanhui; Ji, Haisheng; Feng, Li; Wiegelmann, Thomas; Inhester, Bernd
2014-08-20
In this paper, we present a variety of well-observed dynamic behaviors for the flaring and peripheral magnetic loops of the M6.6 class extreme limb flare that occurred on 2011 February 24 (SOL2011-02-24T07:20) from EUV observations by the Atmospheric Imaging Assembly on the Solar Dynamics Observatory and X-ray observations by RHESSI. The flaring loop motion confirms the earlier contraction-expansion picture. We find that the U-shaped trajectory delineated by the X-ray corona source of the flare roughly follows the direction of a filament eruption associated with the flare. Different temperature structures of the coronal source during the contraction and expansion phases strongly suggest different kinds of magnetic reconnection processes. For some peripheral loops, we discover that their dynamics are closely correlated with the filament eruption. During the slow rising to abrupt, fast rising of the filament, overlying peripheral magnetic loops display different responses. Two magnetic loops on the elbow of the active region had a slow descending motion followed by an abrupt successive fast contraction, while magnetic loops on the top of the filament were pushed outward, slowly being inflated for a while and then erupting as a moving front. We show that the filament activation and eruption play a dominant role in determining the dynamics of the overlying peripheral coronal magnetic loops.
Single-vortex pinning and penetration depth in superconducting NdFeAsO1-xFx
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Zhang, Jessie T.; Kim, Jeehoon; Huefner, Magdalena; Ye, Cun; Kim, Stella; Canfield, Paul C.; Prozorov, Ruslan; Auslaender, Ophir M.; Hoffman, Jennifer E.
2015-10-12
We use a magnetic force microscope (MFM) to investigate single vortex pinning and penetration depth in NdFeAsO1-xFx, one of the highest-Tc iron-based superconductors. In fields up to 20 Gauss, we observe a disordered vortex arrangement, implying that the pinning forces are stronger than the vortex-vortex interactions. We measure the typical force to depin a single vortex, Fdepin ? 4.5 pN, corresponding to a critical current up to Jc ? 7×105 A/cm2. As a result, our MFM measurements allow the first local and absolute determination of the superconducting in-plane penetration depth in NdFeAsO1-xFx, ?ab = 320 ± 60 nm, which ismore »larger than previous bulk measurements.« less
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 ...
Khabarova, O; Li, G; Roux, J A le; Webb, G M; Dosch, A; Malandraki, O E
2015-01-01
Increases of ion fluxes in the keV-MeV range are sometimes observed near the heliospheric current sheet (HCS) during periods when other sources are absent. These resemble solar energetic particle (SEP) events, but the events are weaker and apparently local. Conventional explanations based on either shock acceleration of charged particles or particle acceleration due to magnetic reconnection at interplanetary current sheets are not persuasive. We suggest instead that recurrent magnetic reconnection occurs at the HCS and smaller current sheets in the solar wind (Zharkova & Khabarova 2012), of which a consequence is particle energization by the dynamically evolving secondary current sheets and magnetic islands (Zank et al. 2014; Drake et al. 2006a). The effectiveness of the trapping and acceleration process associated with magnetic islands depends in part on the topology of the HCS. We show that the HCS possesses ripples superimposed on the large-scale flat or wavy structure. We conjecture that the ripples c...
Boyer, Edmond
866 IEEE TRANSACTIONS ON MAGNETICS, VOL. 44, NO. 6, JUNE 2008 Dynamical Models for Eddy Current accurate dynamical models for representing eddy currents are studied. The simulation of the relay is provided. Index Terms--AC circuit breakers (CBs), eddy currents, magnetic hysteresis, optimization methods
Tunable magnetization dynamics in disordered FePdPt ternary alloys: Effects of spin orbit coupling
Ma, L.; Fan, W. J. Chen, F. L.; Zhou, S. M.; Li, S. F.; Lai, T. S.; He, P.; Xu, X. G.; Jiang, Y.
2014-09-21
The magnetization dynamics of disordered Fe?.?(Pd{sub 1–x}Pt{sub x})?.? alloy films was studied by time-resolved magneto-optical Kerr effect and ferromagnetic resonance. The intrinsic Gilbert damping parameter ?? and the resonance linewidth change linearly with the Pt atomic concentration. In particular, the induced in-plane uniaxial anisotropy constant K{sub U} also increases for x increasing from 0 to 1. All these results can be attributed to the tuning effect of the spin orbit coupling. For the disordered ternary alloys, an approach is proposed to control the induced in-plane uniaxial anisotropy, different from conventional thermal treat methods, which is helpful to design and fabrications of spintronic devices.
Luo, Shaohua [School of Automation, Chongqing University, Chongqing 400044, China and College of Mechanical Engineering, Hunan University of Arts and Science, Hunan 415000 (China)
2014-09-01
This paper is concerned with the problem of adaptive fuzzy dynamic surface control (DSC) for the permanent magnet synchronous motor (PMSM) system with chaotic behavior, disturbance and unknown control gain and parameters. Nussbaum gain is adopted to cope with the situation that the control gain is unknown. And the unknown items can be estimated by fuzzy logic system. The proposed controller guarantees that all the signals in the closed-loop system are bounded and the system output eventually converges to a small neighborhood of the desired reference signal. Finally, the numerical simulations indicate that the proposed scheme can suppress the chaos of PMSM and show the effectiveness and robustness of the proposed method.
Anomalous magnetic structure and spin dynamics in magnetoelectric LiFePO4
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Toft-Petersen, Rasmus; Reehuis, Manfred; Jensen, Thomas B. S.; Andersen, Niels H.; Li, Jiying; Le, Manh Duc; Laver, Mark; Niedermayer, Christof; Klemke, Bastian; Lefmann, Kim; et al
2015-07-06
We report significant details of the magnetic structure and spin dynamics of LiFePO4 obtained by single-crystal neutron scattering. Our results confirm a previously reported collinear rotation of the spins away from the principal b axis, and they determine that the rotation is toward the a axis. In addition, we find a significant spin-canting component along c. Furthermore, the possible causes of these components are discussed, and their significance for the magnetoelectric effect is analyzed. Inelastic neutron scattering along the three principal directions reveals a highly anisotropic hard plane consistent with earlier susceptibility measurements. While using a spin Hamiltonian, we showmore »that the spin dimensionality is intermediate between XY- and Ising-like, with an easy b axis and a hard c axis. It is shown that both next-nearest neighbor exchange couplings in the bc plane are in competition with the strongest nearest neighbor coupling.« less
Colored-noise magnetization dynamics: from weakly to strongly correlated noise
Tranchida, Julien; Nicolis, Stam
2015-01-01
Statistical averaging theorems allow us to derive a set of equations for the averaged magnetization dynamics in the presence of colored (non-Markovian) noise. The non-Markovian character of the noise is described by a finite auto-correlation time, tau, that can be identified with the finite response time of the thermal bath to the system of interest. Hitherto, this model was only tested for the case of weakly correlated noise (when tau is equivalent or smaller than the integration timestep). In order to probe its validity for a broader range of auto-correlation times, a non-Markovian integration model, based on the stochastic Landau-Lifshitz-Gilbert equation is presented. Comparisons between the two models are discussed, and these provide evidence that both formalisms remain equivalent, even for strongly correlated noise (i.e. tau much larger than the integration timestep).
Colored-noise magnetization dynamics: from weakly to strongly correlated noise
Julien Tranchida; Pascal Thibaudeau; Stam Nicolis
2015-11-06
Statistical averaging theorems allow us to derive a set of equations for the averaged magnetization dynamics in the presence of colored (non-Markovian) noise. The non-Markovian character of the noise is described by a finite auto-correlation time, tau, that can be identified with the finite response time of the thermal bath to the system of interest. Hitherto, this model was only tested for the case of weakly correlated noise (when tau is equivalent or smaller than the integration timestep). In order to probe its validity for a broader range of auto-correlation times, a non-Markovian integration model, based on the stochastic Landau-Lifshitz-Gilbert equation is presented. Comparisons between the two models are discussed, and these provide evidence that both formalisms remain equivalent, even for strongly correlated noise (i.e. tau much larger than the integration timestep).
The structure and dynamics of self-assembling colloidal monolayers in oscillating magnetic fields
Alison E. Koser; Nathan C. Keim; Paulo E. Arratia
2013-11-18
Many fascinating phenomena such as large-scale collective flows, enhanced fluid mixing and pattern formation have been observed in so-called active fluids, which are composed of particles that can absorb energy and dissipate it into the fluid medium. For active particles immersed in liquids, fluid-mediated viscous stresses can play an important role on the emergence of collective behavior. Here, we experimentally investigate their role in the dynamics of self-assembling magnetically-driven colloidal particles which can rapidly form organized hexagonal structures. We find that viscous stresses reduce hexagonal ordering, generate smaller clusters, and significantly decrease the rate of cluster formation, all while holding the system at constant number density. Furthermore, we show that time and length scales of cluster formation depend on the Mason number (Mn), or ratio of viscous to magnetic forces, scaling as t / Mn and L / Mn^(1/2). Our results suggest that viscous stresses hinder collective behavior in a self-assembling colloidal system.
Non-linear dynamics of Kelvin-Helmholtz unstable magnetized jets: three-dimensional effects
R. Keppens; G. Toth
1999-01-27
A numerical study of the Kelvin-Helmholtz instability in compressible magnetohydrodynamics is presented. The three-dimensional simulations consider shear flow in a cylindrical jet configuration, embedded in a uniform magnetic field directed along the jet axis. The growth of linear perturbations at specified poloidal and axial mode numbers demonstrate intricate non-linear coupling effects. The physical mechanims leading to induced secondary Kelvin-Helmholtz instabilities at higher mode numbers are identified. The initially weak magnetic field becomes locally dominant in the non-linear dynamics before and during saturation. Thereby, it controls the jet deformation and eventual breakup. The results are obtained using the Versatile Advection Code [G. Toth, Astrophys. Lett. Comm. 34, 245 (1996)], a software package designed to solve general systems of conservation laws. An independent calculation of the same Kelvin-Helmholtz unstable jet configuration using a three-dimensional pseudo-spectral code gives important insights into the coupling and excitation events of the various linear mode numbers.
Anomalous Dynamical Line Shapes in a Quantum Magnet at Finite Temperature
Tennant D. A.; James A.; Lake, B.; Essler, F.H.L.; Notbohm, S.; Mikeska, H.-J.; Fielden, J.; Kogerler,, P.; Canfield, P.C.; Telling, M.T.F.
2012-01-04
The effect of thermal fluctuations on the dynamics of a gapped quantum magnet is studied using inelastic neutron scattering on copper nitrate, a model material for the spin-1/2, one-dimensional (1D) bond alternating Heisenberg chain. A large, highly deuterated, single-crystal sample of copper nitrate is produced using a solution growth method and measurements are made using the high-resolution backscattering spectrometer OSIRIS at the ISIS Facility. Theoretical calculations and numerical analysis are combined to interpret the physical origin of the thermal effects observed in the magnetic spectra. The primary observations are (1) a thermally induced central peak due to intraband scattering, which is similar to Villain scattering familiar from soliton systems in 1D, and (2) the one-magnon quasiparticle pole is seen to develop with temperature into an asymmetric continuum of scattering. We relate this asymmetric line broadening to a thermal strongly correlated state caused by hard-core constraints and quasiparticle interactions. These findings are a counter example to recent assertions of the universality of line broadening in 1D systems and are applicable to a broad range of quantum systems.
Localized Induction Equation for Stretched Vortex Filament
Kimiaki Konno; Hiroshi Kakuhata
2006-03-02
We study numerically the motion of the stretched vortex filaments by using the localized induction equation with the stretch and that without the stretch.
Stanley, H. Eugene
Clustering Dynamics in Water/Methanol Mixtures: A Nuclear Magnetic Resonance Study at 205 K functional groups in water/methanol mixtures at different methanol molar fractions (XMeOH ) 0, 0.04, 0.1, 0 in the mixtures, at all the methanol molar fractions, are faster than those of pure water and methanol because
Brandt, Rebekah Katherine
2012-01-01
H z , and an oscillating magnetic field is applied in the x-experiment, where an oscillating magnetic field drives theApplying magnetic field pulses or oscillating fields via
Quantum dynamics and magneto-structural correlations in molecule based magnets
Beedle, Christopher Craig
2010-01-01
molar magnetization, N is Avogadro’s number, and ? is themolar magnetization, N is Avogadro’s number, and ? is themolar magnetization, N is Avogadro’s number, and ? is the
Nonlinear Dynamics of a Rotor Supported by Homopolar Magnetic Bearings with Saturation
Kang, Kyungdae
2011-02-22
control loop that includes low pass filter effects. An analytical magnetization curve model is proposed to predict the nonlinear magnetic force under the influence of the magnetic flux saturation more accurately. The modified Langmuir method with the novel...
E. N. Egorov; A. E. Hramov
2006-06-27
The effect of the strength of the focusing magnetic field on chaotic dynamic processes occurring inan electron beam with a virtual cathode, as well as on the processes whereby the structures form in the beamand interact with each other, is studied by means of two-dimensional numerical simulations based on solving a self-consistent set of Vlasov-Maxwell equations. It is shown that, as the focusing magnetic field is decreased,the dynamics of an electron beam with a virtual cathode becomes more complicated due to the formation andinteraction of spatio-temporal longitudinal and transverse structures in the interaction region of a vircator. The optimum efficiency of the interaction of an electron beam with the electromagnetic field of the vircator isachieved at a comparatively weak external magnetic field and is determined by the fundamentally two-dimensional nature of the motion of the beam electrons near the virtual cathode.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Gilbert, Dustin A.; Ye, Li; Varea, Aïda; Agramunt-Puig, Sebastià; del Valle, Nuria; Navau, Carles; López-Barbera, José Francisco; Buchanan, Kristen S.; Hoffmann, Axel; Sánchez, Alvar; et al
2015-04-28
Magnetic vortices have generated intense interest in recent years due to their unique reversal mechanisms, fascinating topological properties, and exciting potential applications. In addition, the exchange coupling of magnetic vortices to antiferromagnets has also been shown to lead to a range of novel phenomena and functionalities. Here we report a new magnetization reversal mode of magnetic vortices in exchange coupled Ir20Mn80/Fe20Ni80 microdots: distorted viscous vortex reversal. In contrast to the previously known or proposed reversal modes, the vortex is distorted close to the interface and viscously dragged due to the uncompensated spins of a thin antiferromagnet, which leads to unexpectedmore »asymmetries in the annihilation and nucleation fields. These results provide a deeper understanding of the physics of exchange coupled vortices and may also have important implications for applications involving exchange coupled nanostructures.« less
Light propagation around a relativistic vortex flow of dielectric medium
B. Linet
2000-11-06
We determine the path of the light around a dielectric vortex described by the relativistic vortex flow of a perfect fluid.
Vortex Hydro Energy Develops Transformational Technology to Harness...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Vortex Hydro Energy Develops Transformational Technology to Harness Energy from Water Currents Vortex Hydro Energy Develops Transformational Technology to Harness Energy from Water...
Kervalishvili, N A
2015-01-01
The results of experimental investigations of electron ejection from gas-discharge nonneutral electron plasma at the formation and radial oscillations of vortex structure have been presented. The electrons are injected from the vortex structure and the adjacent region of electron sheath in the form of pulses the duration and periodicity of which are determined by the processes of evolution and dynamics of this structure. The possible mechanisms of pulse ejection of electrons are considered. The influence of electron ejection on other processes in discharge electron sheath is analyzed.
Dunin-Borkowski, Rafal E.
yielding an intermediate magnetic state between the vortex state and the tube state is found closure vortex states but in rings with thickness variations, an effective stray field occurs. Using. The interaction between exchange coupled rings leads to antiparallel vortex states and extended onion states
Relativistic Electron Vortex Beams: Angular Momentum and Spin-Orbit Interaction
Konstantin Y. Bliokh; Mark R. Dennis; Franco Nori
2011-09-11
Motivated by the recent discovery of electron vortex beams carrying orbital angular momentum (AM), we construct exact Bessel-beam solutions of the Dirac equation. They describe relativistic and nonparaxial corrections to the scalar electron beams. We describe the spin and orbital AM of the electron with Berry-phase corrections and predict the intrinsic spin-orbit coupling in free space. This can be observed as a spin-dependent probability distribution of the focused electron vortex beams. Moreover, the magnetic moment is calculated, which shows different $g$-factors for spin and orbital AM and also contains the Berry-phase correction.
V. E. Shapiro
2011-09-22
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.
A Robust Numerical Method for Integration of Point-Vortex Trajectories in Two Dimensions
Spencer A. Smith; Bruce M. Boghosian
2010-11-19
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.
EXISTENCE OF KNOTTED VORTEX TUBES IN STEADY EULER FLOWS
Enciso, Alberto
EXISTENCE OF KNOTTED VORTEX TUBES IN STEADY EULER FLOWS ALBERTO ENCISO AND DANIEL PERALTA-SALAS Abstract. We prove the existence of knotted and linked thin vortex tubes for steady solutions of vortex tubes of a Beltrami field that tends to zero at infinity. The structure of the vortex lines
Vortex pinning by inhomogeneities in type-II superconductors
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
Under consideration for publication in J. Fluid Mech. 1 Some steady axisymmetric vortex ows past
Fornberg, Bengt
include vortex rings, bounded vortices attached to the sphere and in nite vortex tubes. Four families to be considered: vortex rings, bounded vortices attached to the sphere, and vortex tubes" extending to in nity. Fornberg and K. Miller = 0: attached vortex vortex ring > 0: vortex tube Figure 1. Examples
Dussaux, A.; Rache Salles, B.; Jenkins, A. S.; Bortolotti, P.; Grollier, J.; Cros, V.; Fert, A.; Khvalkovskiy, A. V.; Kubota, H.; Fukushima, A.; Yakushiji, K.; Yuasa, S.
2014-07-14
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.
Observation of the Larmor and Gouy Rotations with Electron Vortex Beams
Giulio Guzzinati; Peter Schattschneider; Konstantin Bliokh; Franco Nori; Jo Verbeeck
2013-02-25
Electron vortex beams carrying intrinsic orbital angular momentum (OAM) are produced in electron microscopes where they are controlled and focused using magnetic lenses. We observe various rotational phenomena arising from the interaction between the OAM and magnetic lenses. First, the Zeeman coupling, proportional to the OAM and magnetic field strength, produces an OAM-independent Larmor rotation of a mode superposition inside the lens. Second, hen passing through the focal plane, the electron beam acquires an additional Gouy phase dependent on the absolute value of the OAM. This brings about the Gouy rotation of the superposition image proportional to the sign of the OAM. A combination of the Larmor and Gouy effects can result in the addition (or subtraction) of rotations, depending on the OAM sign. This behaviour is unique to electron vortex beams and has no optical counterpart, as Larmor rotation occurs only for charged particles. Our experimental results are in agreement with recent theoretical predictions.
Vortex reconnections in atomic condensates at finite temperature A. J. Allen1
Zuccher, Simone
superfluid turbu- lence, a phenomenon recently also reported in trapped atomic BoseEinstein condensates, vortex dynamics, quantum turbulence, Bose-Einstein condensates, Superfluid He In classical hydrodynamics 3 He and atomic BoseEinstein condensates (BECs) is currently debated. For example, one would like
Vortex Ring Interaction with a Particle Layer: Implications for Sediment Transport
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
Microoptomechanical pumps assembled and driven by holographic optical vortex Kosta Ladavac
Grier, David
Microoptomechanical pumps assembled and driven by holographic optical vortex arrays Kosta Ladavac into dynamically reconfigurable microoptomechanical pumps assembled by optical gradient forces and actuated systems has created a need for new meth ods to pump and steer fluids through micrometerscale channels
Microoptomechanical pumps assembled and driven by holographic optical vortex Kosta Ladavac
Grier, David
Microoptomechanical pumps assembled and driven by holographic optical vortex arrays Kosta Ladavac into dynamically reconfigurable microoptomechanical pumps assembled by optical gradient forces and actuated systems has created a need for new meth- ods to pump and steer fluids through micrometer-scale channels
A Lagrangian approach to identifying vortex pinch-off Clara O'Farrell1
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
Aging memory and glassiness of a driven vortex , Guohong Li1
Andrei, Eva Y.
1 Aging memory and glassiness of a driven vortex system. Xu Du1 , Guohong Li1 , Eva Y. Andrei1 , M memory, aging and nonlinear-dynamics. Glasses[1-11], interfaces[12] and fractures are some examples[13 the deviation from equilibrium. After removing the force, the system ages with time and its subsequent response
Zutavern, Zachary Scott
2004-09-30
Historical attempts to measure forces in magnetic bearings have been unsuccessful as a result of relatively high uncertainties. Recent advances in the strain-gauge technology have provided a new method for measuring magnetic bearing forces. Fiber...
Gusev, Guennady
, Boite Postale 166, F-38042 Grenoble, France J. C. Portal High Magnetic Field Laboratory CNRS, Boite, Russia Received 30 April 1996 The classical dynamics of a charged particle colliding ballistically around
Raju, Makaraju Srinivasa; Gopinath, Pramod, E-mail: pramod@iist.ac.in [Department of Physics, Indian Institute of Space Science and Technology, Thiruvananthapuram 695547 (India); Singh, R. K.; Kumar, Ajai [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)
2014-10-21
The expansion dynamics and spectral behaviour of plasma produced by a Nd:YAG laser (?=1.064 ?m, pulse width: 8 ns) from barium target and expanding in 0.45 T transverse magnetic field in vacuum (10??Torr pressure) are investigated using time-of-flight optical emission spectroscopy. The experiments are carried out at various laser fluences from 12 to 31 J/cm². The temporal profiles of neutral (Ba I 553.5 and 577.7 nm) lines are temporally broadened, while that of ionic (Ba II 413.0 and 455.4 nm) lines show strong confinement in the presence of a magnetic field. In the absence of magnetic field, the temporal profile of Ba I 553.5 nm is exactly reproduced by fitting with two Shifted Maxwell Boltzmann (SMB) Distribution components, while in the presence of a magnetic field the profile could only be fitted with three components. The field enhanced and field induced SMB components of neutral profile are correlated with populations of ground state, metastable states, and long-lived Rydberg states present in the barium plasma, while SMB components of ionic lines are explained on the basis of the presence of super-elastic collisions among the excited species in the plasma. The spatial variation of electron temperature and temporal variation of electron density are deduced and correlated to the different collisional processes in the barium plasma. The ionic profiles show efficient confinement in the presence of a magnetic field at higher fluences.
Shear Banding and Spatiotemporal Oscillations in Vortex Matter in Nanostructured Superconductors
C. Reichhardt; C. J. Olson Reichhardt
2009-12-16
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.
Bluff Body Flow Simulation Using a Vortex Element Method
Anthony Leonard; Phillippe Chatelain; Michael Rebel
2004-09-30
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.
Kostylev, M.
2014-06-21
In this work, we derive the interface exchange boundary conditions for the classical linear dynamics of magnetization in ferromagnetic layers with the interface Dzyaloshinskii-Moriya interaction (IDMI). We show that IDMI leads to pinning of dynamic magnetization at the interface. An unusual peculiarity of the IDMI-based pinning is that its scales as the spin-wave wave number. We incorporate these boundary conditions into an existing numerical model for the dynamics of the Damon-Eshbach spin wave in ferromagnetic films. IDMI affects the dispersion and the frequency non-reciprocity of the travelling Damon-Eshbach spin wave. For a broad range of film thicknesses L and wave numbers, the results of the numerical simulations of the spin wave dispersion are in a good agreement with a simple analytical expression, which shows that the contribution of IDMI to the dispersion scales as 1/L, similarly to the effect of other types of interfacial anisotropy. Suggestions to experimentalists how to detect the presence of IDMI in a spin wave experiment are given.
Airfoil Vortex Induced Vibration suppression devices
Lee, Evan J. (Evan Joseph)
2007-01-01
Vortex Induced Vibrations (VIV) is a major concern of the offshore oil industry. This problem leads to fatigue failure in the marine risers and causes costly replacement of the risers. Appendages such as helical strakes ...
Magnetorotational instability, current relaxation, and current-vortex sheet
Silveira, F. E. M. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adélia, 166, CEP 09210-170, Bairro Bangu, Santo André, SP (Brazil)] [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adélia, 166, CEP 09210-170, Bairro Bangu, Santo André, SP (Brazil); Galvão, R. M. O. [Instituto de Física, Universidade de São Paulo, Rua do Matão, Travessa R, 187, CEP 05508-090, Cidade Universitária, São Paulo, SP (Brazil)] [Instituto de Física, Universidade de São Paulo, Rua do Matão, Travessa R, 187, CEP 05508-090, Cidade Universitária, São Paulo, SP (Brazil)
2013-08-15
The conjugate effect of current relaxation and of current-vortex sheet formation on the magnetorotational instability is explored in a conducting fluid. It is found that the relative amplification of the magnetic viscosity from marginal stability to the instability determined by the maximum growth rate is around 924% when resistive effects dominate, while the corresponding quantity is around 220% in the ideal limit. This shows that the conjugate influence is much more efficient to amplify the magnetic viscosity than just the effect due to the standard magnetic tension. It is also found that the magnitude of the magnetic viscosity is effectively enhanced by the conjugate influence. The results presented here may contribute to the understanding of the various processes that play a significant role in the mechanism of anomalous viscosity observed in Keplerian disks. It is argued that the new effect shall be relevant in thin accretion disks. It is also mentioned that the proposed formulation may be of interest for some theories of magnetic reconnection. Possible extensions of this work are suggested.
Zhou, R. J.; Hu, L. Q.; Li, E. Z.; Xu, M.; Zhong, G. Q.; Xu, L. Q.; Lin, S. Y. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)
2013-03-15
The nature of runaway electrons is such that the confinement and dynamics of the electrons can be strongly affected by magnetic fluctuations in plasma. Experimental results in the HT-7 tokamak indicated significant losses of runaway electrons due to magnetic fluctuations, but the loss processes did not only rely on the fluctuation amplitude. Efficient radial runaway transport required that there were no more than small regions of the plasma volume in which there was very low transport of runaways. A radial runaway diffusion coefficient of D{sub r} Almost-Equal-To 10 m{sup 2}s{sup -1} was derived for the loss processes, and diffusion coefficient near the resonant magnetic surfaces and shielding factor #Greek Upsilon With Hook Symbol#=0.8 were deduced. Test particle equations were used to analyze the effect of magnetic fluctuations on runaway dynamics. It was found that the maximum energy that runaways can gain is very sensitive to the value of {alpha}{sub s} (i.e., the fraction of plasma volume with reduced transport). {alpha}{sub s}=(0.28-0.33) was found for the loss processes in the experiment, and maximum runaway energy could be controlled in the range of E=(4 MeV-6 MeV) in this case. Additionally, to control the maximum runaway energy below 5 MeV, the normalized electric field needed to be under a critical value D{sub {alpha}}=6.8, and the amplitude normalized magnetic fluctuations b(tilde sign) needed to be at least of the order of b(tilde sign) Almost-Equal-To 3 Multiplication-Sign 10{sup -5}.
THE NONPOTENTIALITY OF ACTIVE-REGION CORONAE AND THE DYNAMICS OF THE PHOTOSPHERIC MAGNETIC FIELD
Schrijver, Karel
The magnetic field in the solar photosphere frequently carries strong electric currents, even though the global that the global coronal magnetic field is often largely potential, provided that high-current systems induced by the pressure of the solar wind plasma are allowed for. The most commonly used model, the potential-field source
Topological analysis of paraxially scattered electron vortex beams
Axel Lubk; Laura Clark; Giulio Guzzinati; Jo Verbeeck
2014-10-10
We investigate topological aspects of sub-nm electron vortex beams upon elastic propagation through atomic scattering potentials. Two main aspects can be distinguished: (i) Significantly reduced delocalization compared to a similar non-vortex beam if the beam centers on an atomic column and (ii) site symmetry dependent splitting of higher-order vortex beams. Furthermore, the results provide insight into the complex vortex line fabric within the elastically scattered wave containing characteristic vortex loops predominantly attached to atomic columns and characteristic twists of vortex lines around atomic columns.
MAP, MAC, and Vortex-rings Configurations in the Weinberg-Salam Model
Rosy Teh; Ban-Loong Ng; Khai-Ming Wong
2015-03-20
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 $\\theta_W=\\frac{\\pi}{4}$.
Improved UTE-based attenuation correction for cranial PET-MR using dynamic magnetic field monitoring
Aitken, A. P.; Giese, D.; Tsoumpas, C.; Schleyer, P.; Kozerke, S.; Prieto, C.; Schaeffter, T., E-mail: Tobias.Schaeffter@kcl.ac.uk [Department of Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King's College London, King's Health Partners, St. Thomas Hospital, London SE1 7EH (United Kingdom)
2014-01-15
Purpose: Ultrashort echo time (UTE) MRI has been proposed as a way to produce segmented attenuation maps for PET, as it provides contrast between bone, air, and soft tissue. However, UTE sequences require samples to be acquired during rapidly changing gradient fields, which makes the resulting images prone to eddy current artifacts. In this work it is demonstrated that this can lead to misclassification of tissues in segmented attenuation maps (AC maps) and that these effects can be corrected for by measuring the true k-space trajectories using a magnetic field camera. Methods: The k-space trajectories during a dual echo UTE sequence were measured using a dynamic magnetic field camera. UTE images were reconstructed using nominal trajectories and again using the measured trajectories. A numerical phantom was used to demonstrate the effect of reconstructing with incorrect trajectories. Images of an ovine leg phantom were reconstructed and segmented and the resulting attenuation maps were compared to a segmented map derived from a CT scan of the same phantom, using the Dice similarity measure. The feasibility of the proposed method was demonstrated inin vivo cranial imaging in five healthy volunteers. Simulated PET data were generated for one volunteer to show the impact of misclassifications on the PET reconstruction. Results: Images of the numerical phantom exhibited blurring and edge artifacts on the bone–tissue and air–tissue interfaces when nominal k-space trajectories were used, leading to misclassification of soft tissue as bone and misclassification of bone as air. Images of the tissue phantom and thein vivo cranial images exhibited the same artifacts. The artifacts were greatly reduced when the measured trajectories were used. For the tissue phantom, the Dice coefficient for bone in MR relative to CT was 0.616 using the nominal trajectories and 0.814 using the measured trajectories. The Dice coefficients for soft tissue were 0.933 and 0.934 for the nominal and measured cases, respectively. For air the corresponding figures were 0.991 and 0.993. Compared to an unattenuated reference image, the mean error in simulated PET uptake in the brain was 9.16% when AC maps derived from nominal trajectories was used, with errors in the SUV{sub max} for simulated lesions in the range of 7.17%–12.19%. Corresponding figures when AC maps derived from measured trajectories were used were 0.34% (mean error) and ?0.21% to +1.81% (lesions). Conclusions: Eddy current artifacts in UTE imaging can be corrected for by measuring the true k-space trajectories during a calibration scan and using them in subsequent image reconstructions. This improves the accuracy of segmented PET attenuation maps derived from UTE sequences and subsequent PET reconstruction.
Pal, S.; Das, K.; Barman, A., E-mail: abarman@ybose.res.in [Thematic Unit of Excellence on Nanodevice Technology and Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Klos, J. W.; Gruszecki, P.; Krawczyk, M., E-mail: krawczyk@amu.edu.pl [Faculty of Physics, A. Mickiewicz University in Poznan, Umultowska 85, 61-614 Pozna? (Poland); Hellwig, O. [San Jose Research Center, HGST, a Western Digital Company, 3403 Yerba Buena Rd., San Jose, California 95135 (United States)
2014-10-20
We present an all-optical time-resolved measurement of spin wave (SW) dynamics in a series of antidot lattices based on [Co(0.75?nm)/Pd(0.9?nm)]{sub 8} multilayer (ML) systems with perpendicular magnetic anisotropy. The spectra depend significantly on the areal density of the antidots. The observed SW modes are qualitatively reproduced by the plane wave method. The interesting results found in our measurements and calculations at small lattice constants can be attributed to the increase of areal density of the shells with modified magnetic properties probably due to distortion of the regular ML structure by the Ga ion bombardment and to increased coupling between localized modes. We propose and discuss the possible mechanisms for this coupling including exchange interaction, tunnelling, and dipolar interactions.
Size-dependent magnetic ordering and spin-dynamics in DyPO4 and GdPO4 nanoparticles
Evangelisti, Marco; Sorop, Tibi G; Bakharev, Oleg N; Visser, Dirk; Hillier, Adrian D.; Alonso, Juan; Haase, Markus; Boatner, Lynn A; De Jongh, L. Jos
2011-01-01
Low-temperature magnetic susceptibility and heat capacity measurements on nanoparticles (d 2.6 nm) of the antiferromagnetic compounds DyPO4 (TN = 3:4 K) and GdPO4 (TN = 0:77 K) provide clear demonstrations of finite-size effects, which limit the divergence of the magnetic correlation lengths, thereby suppressing the bulk long-range magnetic ordering transitions. Instead, the incomplete antiferromagnetic order inside the particles leads to the formation of net magnetic moments on the particles. For the nanoparticles of Ising-type DyPO4 superparamagnetic blocking is found in the ac-susceptibility at 1 K, those of the XY-type GdPO4 analogue show a dipolar spin-glass transition at 0:2 K. Monte Carlo simulations for the magnetic heat capacities of both bulk and nanoparticle samples are in agreement with the experimental data. Strong size effects are also apparent in the Dy3+ and Gd3+ spin-dynamics, which were studied by zero-field SR relaxation and high-field 31P-NMR nuclear relaxation measurements. The freezing transitions observed in the ac-susceptibility of the nanoparticles also appear as peaks in the temperature dependence of the zero-field SR rates, but at slightly higher temperatures - as to be expected from the higher frequency of the muon probe. For both bulk and nanoparticles of GdPO4, the muon and 31P-NMR rates are for T 5 K dominated by exchange-narrowed hyperfine broadening arising from the electron spin-spin interactions inside the particles. The dipolar hyperfine interactions acting on the muons and the 31P are, however, much reduced in the nanoparticles. For the DyPO4 analogues the high-temperature rates appear to be fully determined by electron spin-lattice relaxation processes.
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.
2011-08-01
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.
Rogue Waves on a Vortex Filament St Anne's College
Tarrès, Pierre
Rogue Waves on a Vortex Filament Rehan Shah St Anne's College University of Oxford A dissertation;Abstract The presence of a standing soliton on a vortex filament has been demonstrated theoretically of the local induction approximation (LIA) governing the motion of a thin vortex filament to those of nonlinear
Optical vortex array in spatially varying lattice
Kapoor, Amit; Senthilkumaran, P; Joseph, Joby
2015-01-01
We present an experimental method based on a modified multiple beam interference approach to generate an optical vortex array arranged in a spatially varying lattice. This method involves two steps which are: numerical synthesis of a consistent phase mask by using two-dimensional integrated phase gradient calculations and experimental implementation of produced phase mask by utilizing a phase only spatial light modulator in an optical 4f Fourier filtering setup. This method enables an independent variation of the orientation and period of the vortex lattice. As working examples, we provide the experimental demonstration of various spatially variant optical vortex lattices. We further confirm the existence of optical vortices by formation of fork fringes. Such lattices may find applications in size dependent trapping, sorting, manipulation and photonic crystals.
A. E. Koshelev; I. A. Sadovskyy; C. L. Phillips; A. Glatz
2015-10-01
Introducing nanoparticles into superconducting materials has emerged as an efficient route to enhance their current-carrying capability. We address the problem of optimizing vortex pinning landscape for randomly distributed metallic spherical inclusions using large-scale numerical simulations of time-dependent Ginzburg-Landau equations. We found the size and density of particles for which the highest critical current is realized in a fixed magnetic field. For each particle size and magnetic field, the critical current reaches a maximum value at a certain particle density, which typically corresponds to 15-23% of the total volume being replaced by nonsuperconducting material. For fixed diameter, this optimal particle density increases with the magnetic field. Moreover, we found that the optimal particle diameter slowly decreases with the magnetic field from 4.5 to 2.5 coherence lengths at a given temperature. This result shows that pinning landscapes have to be designed for specific applications taking into account relevant magnetic field scales.
Decay of helical Kelvin waves on a quantum vortex filament
Van Gorder, Robert A.
2014-07-15
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.
Dynamical view of pair creation in uniform electric and magnetic fields
Naoto Tanji
2009-05-12
Pair creation in a uniform classical electromagnetic field (Schwinger mechanism) is studied focusing on the time evolution of the distribution of created particles. The time evolution of the distribution in time-dependent fields is also presented as well as effects of back reaction. Motivated by the Glasma flux tube, which may be formed at the initial stage of heavy-ion collisions, we investigate effects of a magnetic field parallel to an electric field, and find that the magnetic field makes the evolution of a fermion system faster.
Sotnikov, V.; Kim, T.; Lundberg, J.; Paraschiv, I.; Mehlhorn, T. A.
2014-05-15
The presence of plasma turbulence can strongly influence propagation properties of electromagnetic signals used for surveillance and communication. In particular, we are interested in the generation of low frequency plasma density irregularities in the form of coherent vortex structures. Interchange or flute type density irregularities in magnetized plasma are associated with Rayleigh-Taylor type instability. These types of density irregularities play an important role in refraction and scattering of high frequency electromagnetic signals propagating in the earth ionosphere, in high energy density physics, and in many other applications. We will discuss scattering of high frequency electromagnetic waves on low frequency density irregularities due to the presence of vortex density structures associated with interchange instability. We will also present particle-in-cell simulation results of electromagnetic scattering on vortex type density structures using the large scale plasma code LSP and compare them with analytical results.
Existence of knotted vortex tubes in steady Euler flows
Alberto Enciso; Daniel Peralta-Salas
2014-10-23
We prove the existence of knotted and linked thin vortex tubes for steady solutions to the incompressible Euler equation in R^3. More precisely, given a finite collection of (possibly linked and knotted) disjoint thin tubes in R^3, we show that they can be transformed with a C^m-small diffeomorphism into a set of vortex tubes of a Beltrami field that tends to zero at infinity. The structure of the vortex lines in the tubes is extremely rich, presenting a positive-measure set of invariant tori and infinitely many periodic vortex lines. The problem of the existence of steady knotted vortex tubes can be traced back to Lord Kelvin.
Szabados, Barna
Permanent Magnet Synchronous Machines Abstract: An experimental investigation is conducted to determine the behaviour of brushless PM synchronous machine parameters in the high speed flux weakening operating range synchronous machines. Special computer assisted measuring techniques are employed using an experimental vector
Investigation of ELM [edge localized mode] Dynamics with the Resonant Magnetic Perturbation Effects
Pankin, Alexei Y.; Kritz, Arnold H.
2011-07-19
Topics covered are: anomalous transport and E x B flow shear effects in the H-mode pedestal; RMP (resonant magnetic perturbation) effects in NSTX discharges; development of a scaling of H-mode pedestal in tokamak plasmas with type I ELMs (edge localized modes); and divertor heat load studies.
Observation of the Dynamical Structure of Turbulence in Plasma Confined by a Dipole Magnetic Field
Mauel, Michael E.
improvements that allow observation of quasi-coherent structures and measurement of multipoint statistics-off-layers of toroidal fusion confinement devices[1416], in the solar wind[17], in magnetized columns of electrons[18 the large-scale structure of turbulence consists of rotating, long-wavelength convective cells with ampli
Dynamics of an electron confined to a "hybrid plane" and interacting with a magnetic field
Raffaele Carlone; Pavel Exner
2010-12-13
We discuss spectral and resonance properties of a Hamiltonian describing motion of an electron moving on a "hybrid surface" consisting on a halfline attached by its endpoints to a plane under influence of a constant magnetic field which interacts with its spin through a Rashba-type term.
Dynamics of multiple viscoelastic carbon nanotube based nanocomposites with axial magnetic field
Karli?i?, Danilo; Caji?, Milan; Murmu, Tony; Kozi?, Predrag; Adhikari, Sondipon
2014-06-21
Nanocomposites and magnetic field effects on nanostructures have received great attention in recent years. A large amount of research work was focused on developing the proper theoretical framework for describing many physical effects appearing in structures on nanoscale level. Great step in this direction was successful application of nonlocal continuum field theory of Eringen. In the present paper, the free transverse vibration analysis is carried out for the system composed of multiple single walled carbon nanotubes (MSWCNT) embedded in a polymer matrix and under the influence of an axial magnetic field. Equivalent nonlocal model of MSWCNT is adopted as viscoelastically coupled multi-nanobeam system (MNBS) under the influence of longitudinal magnetic field. Governing equations of motion are derived using the Newton second low and nonlocal Rayleigh beam theory, which take into account small-scale effects, the effect of nanobeam angular acceleration, internal damping and Maxwell relation. Explicit expressions for complex natural frequency are derived based on the method of separation of variables and trigonometric method for the “Clamped-Chain” system. In addition, an analytical method is proposed in order to obtain asymptotic damped natural frequency and the critical damping ratio, which are independent of boundary conditions and a number of nanobeams in MNBS. The validity of obtained results is confirmed by comparing the results obtained for complex frequencies via trigonometric method with the results obtained by using numerical methods. The influence of the longitudinal magnetic field on the free vibration response of viscoelastically coupled MNBS is discussed in detail. In addition, numerical results are presented to point out the effects of the nonlocal parameter, internal damping, and parameters of viscoelastic medium on complex natural frequencies of the system. The results demonstrate the efficiency of the suggested methodology to find the closed form solutions for the free vibration response of multiple nanostructure systems under the influence of magnetic field.
Morinaga, Atsuo; Toriyama, Koichi; Narui, Hirotaka; Aoki, Takatoshi; Imai, Hiromitsu [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510 (Japan)
2011-05-15
Berry's phase for a whole turn in a conical rotation of the magnetic field with a semiangle {theta} has been clearly manifested free from the dynamical phase shift using the magnetic-field-insensitive two-photon transitions between sodium-ground hyperfine states having different signs of the g factors. The solid angles for states with a positive g factor and with a negative g factor are verified to be 2{pi}(1-cos{theta}) and -2{pi}(1+cos{theta}), respectively, for a right-handed rotation of a magnetic field and a semiangle of 0{<=}{theta}{<=}{pi}/2.
On the evolution of vortex rings with swirl
Naitoh, Takashi, E-mail: naitoh.takashi@nitech.ac.jp [Department of Engineering Physics, Electronics and Mechanics, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Okura, Nobuyuki, E-mail: ohkura@meijo-u.ac.jp [Department of Vehicle and Mechanical Engineering, Meijo University, 1-501 Shiogamaguchi Tempaku-ku, Nagoya 468-8502 (Japan); Gotoh, Toshiyuki, E-mail: gotoh.toshiyuki@nitech.ac.jp [Department of Scientific and Engineering Simulation, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Kato, Yusuke [Controller Business Unit Engineering Division 1, Engineering Department 3, Denso Wave Incorporated, 1 Yoshiike Kusagi Agui-cho, Chita-gun Aichi 470-2297 (Japan)
2014-06-15
A laminar vortex ring with swirl, which has the meridional velocity component inside the vortex core, was experimentally generated by the brief fluid ejection from a rotating outlet. The evolution of the vortex ring was investigated with flow visualizations and particle image velocimetry measurements in order to find the influence of swirling flow in particular upon the transition to turbulence. Immediately after the formation of a vortex ring with swirl, a columnar strong vortex along the symmetric axis is observed in all cases of the present experiment. Then the characteristic fluid discharging from a vortex ring with swirl referred to as “peeling off” appears. The amount of discharging fluid due to the “peeling off” increases with the angular velocity of the rotating outlet. We conjectured that the mechanism generating the “peeling off” is related to the columnar strong vortex by close observations of the spatio-temporal development of the vorticity distribution and the cutting 3D images constructed from the successive cross sections of a vortex ring. While a laminar vortex ring without swirl may develop azimuthal waves around its circumference at some later time and the ring structure subsequently breaks, the swirling flow in a vortex ring core reduces the amplification rate of the azimuthal wavy deformation and preserved its ring structure. Then the traveling distance of a vortex ring can be extended using the swirl flow under certain conditions.
Quenching Processes in Flame-Vortex Interactions
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
Energy harvesting using vortex-induced vibrations of tensioned cables
Grouthier, Clement; de Langre, Emmanuel
2012-01-01
The development of energy harvesting systems based on fluid/structure interactions is part of the global search for innovative tools to produce renewable energy. In this paper, the possibility to harvest energy from a flow using vortex-induced vibrations (VIV) of a tensioned flexible cable is analyzed. The fluid loading on the vibrating solid and resulting dynamics are computed using an appropriate wake-oscillator model, allowing one to perform a systematic parametric study of the efficiency. The generic case of an elastically-mounted rigid cylinder is first investigated, before considering an infinite cable with two different types of energy harvesting : a uniformly spanwise distributed harvesting and then a periodic distribution of discrete harvesting devices. The maximum harvesting efficiency is of the same order for each configuration and is always reached when the solid body and its wake are in a frequency lock-in state.
Neutron Scattering Studies of Vortex Matter in Type-II Superconductors
Xinsheng Ling
2012-02-02
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.
Beninato, A.; Baglio, S.; Andò, B.; Emery, T.; Bulsara, A. R.; Jenkins, C.; Palkar, V.
2013-12-09
Multiferroic (MF) composites, in which magnetic and ferroelectric orders coexist, represent a very attractive class of materials with promising applications in areas, such as spintronics, memories, and sensors. One of the most important multiferroics is the perovskite phase of bismuth ferrite, which exhibits weak magnetoelectric properties at room temperature; its properties can be enhanced by doping with other elements such as dysprosium. A recent paper has demonstrated that a thin film of Bi{sub 0.7}Dy{sub 0.3}FeO{sub 3} shows good magnetoelectric coupling. In separate work it has been shown that a carefully crafted ring connection of N (N odd and N???3) ferroelectric capacitors yields, past a critical point, nonlinear oscillations that can be exploited for electric (E) field sensing. These two results represent the starting point of our work. In this paper the (electrical) hysteresis, experimentally measured in the MF material Bi{sub 0.7}Dy{sub 0.3}FeO{sub 3}, is characterized with the applied magnetic field (B) taken as a control parameter. This yields a “blueprint” for a magnetic (B) field sensor: a ring-oscillator coupling of N?=?3 Sawyer-Tower circuits each underpinned by a mutliferroic element. In this configuration, the changes induced in the ferroelectric behavior by the external or “target” B-field are quantified, thus providing a pathway for very low power and high sensitivity B-field sensing.
Observation of Half-Height Magnetization Steps in Sr2RuO4
Goldbart, Paul M.
of the magnetic moment of a conventional, full-quantum vortex (FQV), for which Dq ¼ Dq ¼ T2p. The Meissner with the entry of single vor- tices. To facilitate this aim, we have fabricated annular samples by drilling, but evades complications arising from the vortex core. For an annular conventional superconductor
Sagar, Vikram; Sengupta, Sudip; Kaw, Predhiman [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)
2012-11-15
Dynamics of a charged particle is studied in the field of a relativistically intense linearly polarized finite duration laser pulse in the presence of a static axial magnetic field. For a finite duration laser pulse whose temporal shape is defined by Gaussian profile, exact analytical expressions are derived for the particle trajectory, momentum, and energy as function of laser phase. From the solutions, it is shown that, unlike for the monochromatic plane wave case, resonant phase locking time between the particle and laser pulse is finite. The net energy transferred to the particle does not increase monotonically but tends to saturate. It is further shown that appropriate tuning of cyclotron frequency of the particle with the characteristic frequency in the pulse spectrum can lead to the generation of accelerated particles with variable energies in MeV-TeV range.
Coelho, J. G.; Cáceres, D. L.; Rueda, J. A.; Ruffini, R. [Dipartimento di Fisica and ICRA, Sapienza Università di Roma, P.le Aldo Moro 5, I-00185 Rome (Italy); Marinho, R. M.; Malheiro, M. [Departamento de Física, Instituto Tecnológico de Aeronáutica, ITA, São José dos Campos, 12228-900 SP (Brazil); Negreiros, R., E-mail: jaziel.coelho@icranet.org, E-mail: jorge.rueda@icra.it, E-mail: m.malheiro@ita.br [Instituto de Física, Universidade Federal Fluminense, UFF, Niterói, 24210-346 RJ (Brazil)
2014-10-10
Massive, highly magnetized white dwarfs with fields up to 10{sup 9} G have been observed and theoretically used for the description of a variety of astrophysical phenomena. Ultramagnetized white dwarfs with uniform interior fields up to 10{sup 18} G have been recently purported to obey a new maximum mass limit, M {sub max} ? 2.58 M {sub ?}, which largely overcomes the traditional Chandrasekhar value, M {sub Ch} ? 1.44 M {sub ?}. Such a larger limit would make these astrophysical objects viable candidates for the explanation of the superluminous population of Type Ia supernovae. We show that several macro and micro physical aspects such as gravitational, dynamical stability, breaking of spherical symmetry, general relativity, inverse ? decay, and pycnonuclear fusion reactions are of most relevance for the self-consistent description of the structure and assessment of stability of these objects. It is shown in this work that the first family of magnetized white dwarfs indeed satisfy all the criteria of stability, while the ultramagnetized white dwarfs are very unlikely to exist in nature since they violate minimal requests of stability. Therefore, the canonical Chandrasekhar mass limit of white dwarfs still has to be applied.
A model of the ULF magnetic and electric field generated from a dust devil
Cummer, Steven A.
A model of the ULF magnetic and electric field generated from a dust devil W. M. Farrell,1 J. R emit ULF magnetic radiation. On Mars, dust devils may also generate such magnetic emissions, which in the vortex wind fields accounts for the magnetic emission. To test this hypothesis in general
Ultrafast Magnetization Dynamics of SrRuO3 Thin Films
Langner, Matthew C
2009-05-19
Itinerant ferromagnet SrRuO3 has drawn interest from physicists due to its unusual transport and magnetic properties as well as from engineers due to its low resistivity and good lattice-matching to other oxide materials. The exact electronic structure remains a mystery, as well as details of the interactions between magnetic and electron transport properties. This thesis describes the use of time-resolved magneto-optical Kerr spectroscopy to study the ferromagnetic resonance of SrRuO3 thin films, where the ferromagnetic resonance is initiated by a sudden change in the easy axis direction in response to a pump pulse. The rotation of the easy axis is induced by laser heating, taking advantage of a temperature-dependent easy axis direction in SrRuO3 thin films. By measuring the change in temperature of the magnetic system in response to the laser pulse, we find that the specific heat is dominated by magnons up to unusually high temperature, ~;;100 K, and thermal diffusion is limited by a boundary resistance between the film and the substrate that is not consistent with standard phonon reflection and scattering models. We observe a high FMR frequency, 250 GHz, and large Gilbert damping parameter, alpha ~;; 1, consistent with strong spin-orbit coupling. We observe a time-dependent change in the easy axis direction on a ps time-scale, and we find that parameters associated with the change in easy axis, as well as the damping parameter, have a non-monotonic temperature dependence similar to that observed in anomalous Hall measurements.
Dynamics of a charged particle around a weakly magnetized naked singularity
Gulmina Zaman Babar; Mubasher Jamil; Yen-Kheng Lim
2015-10-17
We examine the motion of a charged particle in the vicinity of a weakly magnetized naked singularity. The escape velocity and energy of the particle moving around the naked singularity after being kicked by another particle or photon are investigated. Also at the innermost stable circular orbit (ISCO) escape velocity and energy are examined. Effective potential and angular momentum of the particle are also discussed. We discuss the center of mass energy after collision between two particles having same mass and opposite charges moving along the same circular orbit in the opposite direction. It is investigated that under what conditions maximum energy can be produced as a result of collision.
Roach, David J. [Pennsylvania State University, University Park, PA (United States); Dou, Shichen [Pennsylvania State University, University Park, PA (United States); Colby, Ralph H. [Pennsylvania State University, University Park, PA (United States); Mueller, Karl T. [Pacific Northwest Lab., Richland, WA (United States). Environmental Molecular Sciences Lab.
2012-01-01
Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. ^{1}H and ^{7}Li spin-lattice relaxation times (T_{1}) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T_{1} values along with the presence of minima in T_{1} as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies for motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Roach, David J. [Pennsylvania State University, University Park, PA (United States); Dou, Shichen [Pennsylvania State University, University Park, PA (United States); Colby, Ralph H. [Pennsylvania State University, University Park, PA (United States); Mueller, Karl T. [Pacific Northwest Lab., Richland, WA (United States). Environmental Molecular Sciences Lab.
2012-01-01
Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies for motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Roach, David J.; Dou, Shichen; Colby, Ralph H.; Mueller, Karl T.
2012-01-06
Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies formore »motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.« less
Effect of Field Errors in Muon Collider IR Magnets on Beam Dynamics
Alexahin, Y.; Gianfelice-Wendt, E.; Kapin, V.V.; /Fermilab
2012-05-01
In order to achieve peak luminosity of a Muon Collider (MC) in the 10{sup 35} cm{sup -2}s{sup -1} range very small values of beta-function at the interaction point (IP) are necessary ({beta}* {le} 1 cm) while the distance from IP to the first quadrupole can not be made shorter than {approx}6 m as dictated by the necessity of detector protection from backgrounds. In the result the beta-function at the final focus quadrupoles can reach 100 km making beam dynamics very sensitive to all kind of errors. In the present report we consider the effects on momentum acceptance and dynamic aperture of multipole field errors in the body of IR dipoles as well as of fringe-fields in both dipoles and quadrupoles in the ase of 1.5 TeV (c.o.m.) MC. Analysis shows these effects to be strong but correctable with dedicated multipole correctors.
Magnetic Vortex Core Reversal by Low-Field Excitations
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Vortex Bubble Formation in Pair Plasmas
Berezhiani, V I; Mahajan, S M; Aleksi?, B N
2013-01-01
It is shown that delocalized vortex solitons in relativistic pair plasmas with small temperature asymmetries can be unstable for intermediate intensities of the background electromagnetic field. Instability leads to the generation of ever-expanding cavitating bubbles in which the electromagnetic fields are zero. The existence of such electromagnetic bubbles is demonstrated by qualitative arguments based on a hydrodynamic analogy, and by numerical solutions of the appropriate Nonlinear Schr\\"odinger equation with a saturating nonlinearity.
Generation of Mesoscale Magnetic Fields and the Dynamics of Cosmic Ray Acceleration
P. H. Diamond; M. A. Malkov
2005-06-09
The problem of the cosmic ray origin is discussed in connection with their acceleration in supernova remnant shocks. The diffusive shock acceleration mechanism is reviewed and its potential to accelerate particles to the maximum energy of (presumably) galactic cosmic rays ($10^{18}eV $) is considered. It is argued that to reach such energies, a strong magnetic field at scales larger than the particle gyroradius must be created as a result of the acceleration process, itself. One specific mechanism suggested here is based on the generation of Alfven wave at the gyroradius scale with a subsequent transfer to longer scales via interaction with strong acoustic turbulence in the shock precursor. The acoustic turbulence in turn, may be generated by Drury instability or by parametric instability of the Alfven waves.
Weakening of the Stratospheric Polar Vortex by Arctic Sea-Ice Loss
Kim, Baek-Min; Son, Seok-Woo; Min, Seung-Ki; Jeong, Jee-Hoon; Kim, Seong-Joong; Zhang, Xiangdong; Shim, Taehyoun; Yoon, Jin-Ho
2014-09-02
Successive cold winters of severely low temperatures in recent years have had critical social and economic impacts on the mid-latitude continents in the Northern Hemisphere. Although these cold winters are thought to be partly driven by dramatic losses of Arctic sea ice, the mechanism that links sea ice loss to cold winters remains a subject of debate. Here, by conducting observational analyses and model experiments, we show how Arctic sea ice loss and cold winters in extra-polar regions are dynamically connected through the polar stratosphere. We find that decreased sea ice cover during early winter months (November-December), especially over the Barents-Kara seas, enhance the upward propagation of planetary-scale waves with wavenumbers of 1 and 2, subsequently weakening the stratospheric polar vortex in mid-winter (January- February). The weakened polar vortex preferentially induces a negative phase of Arctic Oscillation at the surface, resulting in low temperatures in mid-latitudes.
Electron vortex orbits and merger T. B. Mitchella)
California at San Diego, University of
of the spatially extended vortices are calculated by the point vortex approximation, and simple rules are used resulted in predictions for tim
Dual vortex theory of strongly interacting electrons: A non-Fermi...
Office of Scientific and Technical Information (OSTI)
Dual vortex theory of strongly interacting electrons: A non-Fermi liquid with a twist Citation Details In-Document Search Title: Dual vortex theory of strongly interacting...
Gauge turbulence, topological defect dynamics, and condensation in Higgs models
Gasenzer, Thomas; McLerran, Larry; Pawlowski, Jan M.; Sexty, Dénes
2014-07-28
The real-time dynamics of topological defects and turbulent configurations of gauge fields for electric and magnetic confinement are studied numerically within a 2+1D Abelian Higgs model. It is shown that confinement is appearing in such systems equilibrating after a strong initial quench such as the overpopulation of the infrared modes. While the final equilibrium state does not support confinement, metastable vortex defect configurations appearing in the gauge field are found to be closely related to the appearance of physically observable confined electric and magnetic charges. These phenomena are seen to be intimately related to the approach of a non-thermal fixed point of the far-from-equilibrium dynamical evolution, signaled by universal scaling in the gauge-invariant correlation function of the Higgs field. Even when the parameters of the Higgs action do not support condensate formation in the vacuum, during this approach, transient Higgs condensation is observed. We discuss implications of these results for the far-from-equilibrium dynamics of Yang–Mills fields and potential mechanisms of how confinement and condensation in non-Abelian gauge fields can be understood in terms of the dynamics of Higgs models. These suggest that there is an interesting new class of dynamics of strong coherent turbulent gauge fields with condensates.
Gauge turbulence, topological defect dynamics, and condensation in Higgs models
Gasenzer, Thomas [Heidelberg Univ. (Germany). Inst. for Theoretische Physik; GSI-Darmstadt (Germany). ExtreMe Matter Inst. (EMMI); McLerran, Larry [Brookhaven National Lab. (BNL), Upton, NY (United States). RIKEN Research Center and Physics Dept.; China Central Normal Univ., Wuhan (China). Physics Dept.; Pawlowski, Jan M. [Heidelberg Univ. (Germany). Inst. for Theoretische Physik; GSI-Darmstadt (Germany). ExtreMe Matter Inst. (EMMI); Sexty, Dénes [Heidelberg Univ. (Germany). Inst. for Theoretische Physik; GSI-Darmstadt (Germany). ExtreMe Matter Inst. (EMMI)
2014-10-01
The real-time dynamics of topological defects and turbulent configurations of gauge fields for electric and magnetic confinement are studied numerically within a 2+1D Abelian Higgs model. It is shown that confinement is appearing in such systems equilibrating after a strong initial quench such as the overpopulation of the infrared modes. While the final equilibrium state does not support confinement, metastable vortex defect configurations appearing in the gauge field are found to be closely related to the appearance of physically observable confined electric and magnetic charges. These phenomena are seen to be intimately related to the approach of a non-thermal fixed point of the far-from-equilibrium dynamical evolution, signaled by universal scaling in the gauge-invariant correlation function of the Higgs field. Even when the parameters of the Higgs action do not support condensate formation in the vacuum, during this approach, transient Higgs condensation is observed. We discuss implications of these results for the far-from-equilibrium dynamics of Yang–Mills fields and potential mechanisms of how confinement and condensation in non-Abelian gauge fields can be understood in terms of the dynamics of Higgs models. These suggest that there is an interesting new class of dynamics of strong coherent turbulent gauge fields with condensates.
Gauge turbulence, topological defect dynamics, and condensation in Higgs models
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Gasenzer, Thomas; McLerran, Larry; Pawlowski, Jan M.; Sexty, Dénes
2014-07-28
The real-time dynamics of topological defects and turbulent configurations of gauge fields for electric and magnetic confinement are studied numerically within a 2+1D Abelian Higgs model. It is shown that confinement is appearing in such systems equilibrating after a strong initial quench such as the overpopulation of the infrared modes. While the final equilibrium state does not support confinement, metastable vortex defect configurations appearing in the gauge field are found to be closely related to the appearance of physically observable confined electric and magnetic charges. These phenomena are seen to be intimately related to the approach of a non-thermal fixedmore »point of the far-from-equilibrium dynamical evolution, signaled by universal scaling in the gauge-invariant correlation function of the Higgs field. Even when the parameters of the Higgs action do not support condensate formation in the vacuum, during this approach, transient Higgs condensation is observed. We discuss implications of these results for the far-from-equilibrium dynamics of Yang–Mills fields and potential mechanisms of how confinement and condensation in non-Abelian gauge fields can be understood in terms of the dynamics of Higgs models. These suggest that there is an interesting new class of dynamics of strong coherent turbulent gauge fields with condensates.« less
Ivanov, N. V.; Kakurin, A. M. [National Research Centre “Kurchatov Institute,” 123182 Moscow (Russian Federation)
2014-10-15
Simulation of the magnetic island evolution under Resonant Magnetic Perturbation (RMP) in rotating T-10 tokamak plasma is presented with intent of TEAR code experimental validation. In the T-10 experiment chosen for simulation, the RMP consists of a stationary error field, a magnetic field of the eddy current in the resistive vacuum vessel and magnetic field of the externally applied controlled halo current in the plasma scrape-off layer (SOL). The halo-current loop consists of a rail limiter, plasma SOL, vacuum vessel, and external part of the circuit. Effects of plasma resistivity, viscosity, and RMP are taken into account in the TEAR code based on the two-fluid MHD approximation. Radial distribution of the magnetic flux perturbation is calculated with account of the externally applied RMP. A good agreement is obtained between the simulation results and experimental data for the cases of preprogrammed and feedback-controlled halo current in the plasma SOL.
Almost Optimal Convergence of the Point Vortex Method for Vortex Sheets using Numerical Filtering
Ferguson, Thomas S.
vortices, numerical filtering, discrete CauchyÂKowalewski theorem. AMS subject classifications: primary 65M subsequent modes will be dominated by roundoff error. Since these highest modes are amplified the fastest, singularity formation appears to be generic, even for vortex sheets initially near equilibrium [13, 6, 19
One-vortex moduli space and Ricci flow
Nicholas S. Manton
2008-05-02
The metric on the moduli space of one abelian Higgs vortex on a surface has a natural geometrical evolution as the Bradlow parameter, which determines the vortex size, varies. It is shown by various arguments, and by calculations in special cases, that this geometrical flow has many similarities to Ricci flow.
High-Resolution Simulations of Parallel BladeVortex Interactions
Alonso, Juan J.
to that encountered in the simulation of realistic helicopter bladevortex interaction, but the computational costs aeroacoustics rotor tests [2,3]. These tests were performed on a Mach-scaled Bo-105 rotor and the blade loadsHigh-Resolution Simulations of Parallel BladeVortex Interactions Alasdair Thom University
Finned Tube With Vortex Generators For A Heat Exchanger.
Sohal, Manohar S. (Idaho Falls, ID); O'Brien, James E. (Idaho Falls, ID)
2005-12-20
A system for and method of manufacturing a finned tube for a heat exchanger is disclosed herein. A continuous fin strip is provided with at one pair of vortex generators. A tube is rotated and linearly displaced while the continuous fin strip with vortex generators is spirally wrapped around the tube.
Finned Tube With Vortex Generators For A Heat Exchanger.
Sohal, Monohar S. (Idaho Falls, ID); O'Brien, James E. (Idaho Falls, ID)
2004-09-14
A system for and method of manufacturing a finned tube for a heat exchanger is disclosed herein. A continuous fin strip is provided with at least one pair of vortex generators. A tube is rotated and linearly displaced while the continuous fin strip with vortex generators is spirally wrapped around the tube.
Vortex Lattice Modelling of Winglets on Wind Turbine Blades
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
Snezhko, Oleksiy (Woodridge, IL); Aronson, Igor (Darien, IL); Kwok, Wai-Kwong (Downers Grove, IL)
2011-01-25
Self-assembly of magnetic microparticles in AC magnetic fields. Excitation of the system by an AC magnetic field provides a variety of patterns that can be controlled by adjusting the frequency and the amplitude of the field. At low particle densities the low-frequency magnetic excitation favors cluster phase formation, while high frequency excitation favors chains and netlike structures. For denser configurations, an abrupt transition to the network phase was obtained.
Soh, Wee Tee; Ong, C. K. [Department of Physics, Center for Superconducting and Magnetic Materials, National University of Singapore, 2 Science Drive 3, Singapore 117551 (Singapore); Zhong, Xiaoxi, E-mail: xiaoxi.zhong@gmail.com [Department of Physics, Center for Superconducting and Magnetic Materials, National University of Singapore, 2 Science Drive 3, Singapore 117551 (Singapore); School of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China)
2014-09-15
FeAlSi (Sendust) is known to possess excellent soft magnetic properties comparable to traditional soft magnetic alloys such as NiFe (Permalloy), while having a relatively higher resistance for lower eddy current losses. However, their dynamic magnetic and magneto-transport properties are not well-studied. Via the spin rectification effect, we electrically characterize a series of obliquely sputtered FeAlSi films at ferromagnetic resonance. The variations of the anisotropy fields and damping with oblique angle are extracted and discussed. In particular, two-magnon scattering is found to dominate the damping behavior at high oblique angles. An analysis of the results shows large anomalous Hall effect and anisotropic magneto-resistance across all samples, which decreases sharply with increasing oblique incidence.
Vortex Molecular Crystal and Vortex Plastic Crystal States in Honeycomb and Kagome Pinning Arrays
C. Reichhardt; C. J. Olson Reichhardt
2007-07-26
Using numerical simulations, we investigate vortex configurations and pinning in superconductors with honeycomb and kagome pinning arrays. We find that a variety of novel vortex crystal states can be stabilized at integer and fractional matching field densities. The honeycomb and kagome pinning arrays produce considerably more pronounced commensuration peaks in the critical depinning force than triangular pinning arrays, and also cause additional peaks at noninteger matching fields where a portion of the vortices are located in the large interstitial regions of the pinning lattices. For the honeycomb pinning array, we find matching effects of equal strength at most fillings B/B_\\phi=n/2 for n>2, where n is an integer, in agreement with recent experiments. For kagome pinning arrays, pronounced matching effects generally occur at B/B_\\phi=n/3 for n>3, while for triangular pinning arrays pronounced matching effects are observed only at integer fillings B/B_\\phi=n. At the noninteger matching field peaks in the honeycomb and kagome pinning arrays, the interstitial vortices are arranged in dimer, trimer, and higher order n-mer states that have an overall orientational order. We call these n-mer states "vortex molecular crystals" and "vortex plastic crystals" since they are similar to the states recently observed in colloidal molecular crystal systems. We argue that the vortex molecular crystals have properties in common with certain spin systems such as Ising and n-state Potts models. We show that kagome and honeycomb pinning arrays can be useful for increasing the critical current above that of purely triangular pinning arrays.
Almost-Invariant Tori In The Hamiltonian Dynamics Of 3-D Magnetic Fields Robert L. Dewar 1
Hudson, Stuart
of heat diffusion along chaotic magnetic field lines [1] show that the isotherms correspond very closely-order magnetic island chains. These toroidal surfaces capture the islands' "X-point" and "O-point" closed field field-line Hamiltonian, while the perturbation ! "1(#,$,%) in general gives rise to magnetic islands
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Wulferding, Dirk; Yang, Ilkyu; Yang, Jinho; Lee, Minkyung; Choi, Hee Cheul; Bud'ko, Sergey L.; Canfield, Paul C.; Yeom, Han Woong; Kim, Jeehoon
2015-07-31
We present a local probe study of the magnetic superconductor ErNi2B2C, using magnetic force microscopy at sub-Kelvin temperatures. ErNi2B2C is an ideal system to explore the effects of concomitant superconductivity and ferromagnetism. At 500 mK, far below the transition to a weakly ferromagnetic state, we directly observe a structured magnetic background on the micrometer scale. We determine spatially resolved absolute values of the magnetic penetration depth ? and study its temperature dependence as the system undergoes magnetic phase transitions from paramagnetic to antiferromagnetic, and to weak ferromagnetic, all within the superconducting regime. We estimate the absolute pinning force of Abrikosovmore »vortices, which shows a position dependence and temperature dependence as well, and discuss the possibility of the purported spontaneous vortex formation.« less
Superconducting vortex pinning with artificially prepared nanostructures
Rosen, Yaniv Jacob
Neutron scattering regards to section ‘V.3 Neutron scattering’. I would like tomeasurements, neutron scattering, and magnetic force
Multistage interaction of a shock wave and a strong vortex Shuhai Zhanga
Zhang, Yong-Tao
tube, it traveled back toward the vortex and the interaction between the shock and the vortex tookMultistage interaction of a shock wave and a strong vortex Shuhai Zhanga China Aerodynamics; published online 8 November 2005 The interaction between a shock wave and a strong vortex is simulated
The effect of stoichiometry on vortex flame interactions
Bell, John B.; Brown, Nancy J.; Day, Marcus S.; Frenklach, Michael; Grcar, Joseph F.; Tonse, Shaheen R.
1999-12-01
The interaction of a vortex pair with a premixed flame serves as an important prototype for premixed turbulent combustion. In this study, the authors investigate the interaction of a counter-rotating vortex pair with an initially flat premixed methane flame. The authors focus on characterizing the mechanical nature of the flame-vortex interaction and on the features of the interaction strongly affected by fuel equivalence ratio. The authors compare computational solutions obtained using a time-dependent, two-dimensional adaptive low Mach number combustion algorithm that incorporates GRI-Mech 1.2 for the chemistry, thermodynamics and transport of the chemical species. The authors find that the circulation around the vortex scours gas from the preheat zone in front of the flame, making the interaction extremely sensitive to equivalence ratio. For nearly stoichiometric cases, the peak mole fraction of CH across the flame is relatively insensitive to the vortex whereas for richer flames they observe a substantial and rapid decline in the peak CH mole fraction, commencing early in the flame-vortex interaction. The peak concentration of HCO is found to correlate, in both space and time, with the peak heat release across a broad range of equivalence ratios. The model also predicts a measurable increase in C{sub 2}H{sub 2} as a result of interaction with the vortex, and a marked increase in the low temperature chemistry activity.
Ferromagnetic and antiferromagnetic order in bacterial vortex lattices
Hugo Wioland; Francis G. Woodhouse; Jörn Dunkel; Raymond E. Goldstein
2015-11-16
Despite their inherent non-equilibrium nature, living systems can self-organize in highly ordered collective states that share striking similarities with the thermodynamic equilibrium phases of conventional condensed matter and fluid systems. Examples range from the liquid-crystal-like arrangements of bacterial colonies, microbial suspensions and tissues to the coherent macro-scale dynamics in schools of fish and flocks of birds. Yet, the generic mathematical principles that govern the emergence of structure in such artificial and biological systems are elusive. It is not clear when, or even whether, well-established theoretical concepts describing universal thermostatistics of equilibrium systems can capture and classify ordered states of living matter. Here, we connect these two previously disparate regimes: Through microfluidic experiments and mathematical modelling, we demonstrate that lattices of hydrodynamically coupled bacterial vortices can spontaneously organize into distinct phases of ferro- and antiferromagnetic order. The preferred phase can be controlled by tuning the vortex coupling through changes of the inter-cavity gap widths. The emergence of opposing order regimes is tightly linked to the existence of geometry-induced edge currents, reminiscent of those in quantum systems. Our experimental observations can be rationalized in terms of a generic lattice field theory, suggesting that bacterial spin networks belong to the same universality class as a wide range of equilibrium systems.
Vehstedt, Erin Kathleen
2014-07-18
. In order to overcome these limits, new methods must be developed to reliably transmit and store data more efficiently. The understanding and manipulation of magnetic domain walls (DWs) may play a pivotal role in the development of new non-volatile and down...
Ferroelectric nanostructure having switchable multi-stable vortex states
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)
2009-09-22
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.
Dynamic magnetic interaction in La{sub 2/3}Sr{sub 1/3}MnO{sub 3}/BiFeO{sub 3} heterostructure
Guo, H. Y. [Center for Condensed Matter Sciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan (China); College of Electronic Information and Business, Qingdao Huanghai University, No. 3111, Linghai Rd., Huangdao District, Qingdao 266427 (China); Lin, J. G., E-mail: jglin@ntu.edu.tw [Center for Condensed Matter Sciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan (China); Yang, Jan Chi [Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Rd., HsinChu 30010, Taiwan (China); Chu, Y. H. [Department of Materials Science and Engineering, National Chiao Tung University, 1001 University Rd., HsinChu 30010, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 105, Taiwan (China)
2014-09-15
The La{sub 2/3}Sr{sub 1/3}MnO{sub 3}/BiFeO{sub 3} (LSMO/BFO) heterostructure is studied as probed by temperature-dependent ferromagnetic resonance (FMR). Consistent with the structure analysis, two FMR modes are found for both a single LSMO layer and a LSMO/BFO bilayer grown on DyScO{sub 3}, corresponding to the strained and relaxed phases of LSMO. The FMR linewidth intensity vs temperature curve shows two maxima at 200?K and 140?K in the strained phase of LSMO/BFO bilayer, which is related to the magnetic excitations in BFO. Our results demonstrate a dynamic spin interaction between LSMO and BFO, suggesting an effective route to manipulate the magnetic properties of oxide heterostructures.
Fuel injection of coal slurry using vortex nozzles and valves
Holmes, Allen B. (Rockville, MD)
1989-01-01
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.
Alleviation of fuselage form drag using vortex flows: Final report
Wortman, A.
1987-09-15
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.
Van Gorder, Robert A.
2014-11-15
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.
Superconducting vortex pinning with artificially prepared nanostructures
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
Cirilo-Lombardo, Diego Julio
2015-01-01
The 2-dimensional charge transport with parallel (in plane) magnetic field is considered from the physical and mathematical point of view. To this end, we start with the magnetic field parallel to the plane of charge transport, in sharp contrast to the configuration described by the theorems of Aharonov and Casher where the magnetic field is perpendicular. We explicitly show that the specific form of the arising equation enforce the respective field solution to fulfil the Majorana condition. Consequently, as soon any physical system is represented by this equation, the rise of fields with Majorana type behaviour is immediately explained and predicted. In addition, there exists a quantized particular phase that removes the action of the vector potential producing interesting effects. Such new effects are able to explain due the geometrical framework introduced, several phenomenological results recently obtained in the area of spintronics and quantum electronic devices. The quantum ring as spin filter is worked...
Zeldov, Eli
1996-01-01
. Williams, G. A. Vortex-loop phase transitions in liquid helium, cosmic strings, and high-Tc super the discovery of ®rst-order inverse melting of the lattice formed by magnetic ¯ux lines in a high-temperature of magnetic ¯ux lattice melting and decomposition in the high-Tc superconductor Bi2.15Sr1.95CaCu2O8+x. Nature
Vortex life cycles in two-and three-layer quasi-geostrophic models
Fox, Amanda Katherine
2000-01-01
regimes with jets has occurred. This research attempted to first determine the typical lifetime of a vortex, with considerations of its birth, evolution, and cessation. A vortex census was also performed in an attempt to describe the life cycle...
Mauel, Michael E.
Observation of Centrifugally Driven Interchange Instabilities in a Plasma Confined by a Magnetic) Centrifugally driven interchange instabilities are observed in a laboratory plasma confined by a dipole magnetic electrostatic dipole vortex [3] that transports mass, energy, and charge [4]. The centrifugally driven
Madami, M; Moriyama, T; Tanaka, K; Siracusano, G; Carpentieri, M; Finocchio, G; Tacchi, S; Ono, T; Carlotti, G
2015-01-01
We employed micro-focused Brillouin light scattering to study the amplification of the thermal spin wave eigenmodes by means of a pure spin current, generated by the spin-Hall effect, in a transversely magnetized Pt(4nm)/NiFe(4nm)/SiO2(5nm) layered nanowire with lateral dimensions 500x2750 nm2. The frequency and the cross section of both the center (fundamental) and the edge spin wave modes have been measured as a function of the intensity of the injected dc electric current. The frequency of both modes exhibits a clear redshift while their cross section is greatly enhanced on increasing the intensity of the injected dc. A threshold-like behavior is observed for a value of the injected dc of 2.8 mA. Interestingly an additional mode, localized in the central part of the nanowire, appears at higher frequency on increasing the intensity of the injected dc above the threshold value. Micromagnetic simulations were used to quantitatively reproduce the experimental results and to investigate the complex non-linear d...
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
2012-02-01
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
Vortex Rings in Bio-inspired and Biological Jet Propulsion Paul S. Krueger1, a
Horth, Lisa
of the latter, vortex rings are generated by the transient ejection of a jet from a tube or orifice, which leadsVortex Rings in Bio-inspired and Biological Jet Propulsion Paul S. Krueger1, a , Ali A. Moslemi1,b@odu.edu, e wstewart@uci.edu Keywords: Vortex rings, pulsed jets, propulsion, thrust, propulsive efficiency
COLLISIONS OF VORTEX FILAMENT PAIRS VALERIA BANICA, ERWAN FAOU, AND EVELYNE MIOT
Faou, Erwan
COLLISIONS OF VORTEX FILAMENT PAIRS VALERIA BANICA, ERWAN FAOU, AND EVELYNE MIOT Abstract. We consider the problem of collisions of vortex filaments for a model introduced by Klein, Majda and Damodaran [KMD95] and Zakharov [Z88, Z99] to describe the interaction of almost parallel vortex filaments
Low Head, Vortex Induced Vibrations River Energy Converter
Bernitsas, Michael B.; Dritz, Tad
2006-06-30
Vortex Induced Vibrations Aquatic Clean Energy (VIVACE) is a novel, demonstrated approach to extracting energy from water currents. This invention is based on a phenomenon called Vortex Induced Vibrations (VIV), which was first observed by Leonardo da Vinci in 1504AD. He called it ‘Aeolian Tones.’ For decades, engineers have attempted to prevent this type of vibration from damaging structures, such as offshore platforms, nuclear fuel rods, cables, buildings, and bridges. The underlying concept of the VIVACE Converter is the following: Strengthen rather than spoil vortex shedding; enhance rather than suppress VIV; harness rather than mitigate VIV energy. By maximizing and utilizing this unique phenomenon, VIVACE takes this “problem” and successfully transforms it into a valuable resource for mankind.
Small Winding-Number Expansion: Vortex Solutions at Critical Coupling
Keisuke Ohashi
2015-07-22
We study an axially symmetric solution of a vortex in the Abelian-Higgs model at critical coupling in detail. Here we propose a new idea for a perturbative expansion of a solution, where the winding number of a vortex is naturally extended to be a real number and the solution is expanded with respect to it around its origin. We test this idea on three typical constants contained in the solution and confirm that this expansion works well with the help of the Pad\\'e approximation. For instance, we analytically reproduce the value of the scalar charge of the vortex with an error of $O(10^{-6})$. This expansion is also powerful even for large winding numbers.
Small Winding-Number Expansion: Vortex Solutions at Critical Coupling
Keisuke Ohashi
2015-09-01
We study an axially symmetric solution of a vortex in the Abelian-Higgs model at critical coupling in detail. Here we propose a new idea for a perturbative expansion of a solution, where the winding number of a vortex is naturally extended to be a real number and the solution is expanded with respect to it around its origin. We test this idea on three typical constants contained in the solution and confirm that this expansion works well with the help of the Pad\\'e approximation. For instance, we analytically reproduce the value of the scalar charge of the vortex with an error of $O(10^{-6})$. This expansion is also powerful even for large winding numbers.
Small Winding-Number Expansion: Vortex Solutions at Critical Coupling
Ohashi, Keisuke
2015-01-01
We study an axially symmetric solution of a vortex in the Abelian-Higgs model at critical coupling in detail. Here we propose a new idea for a perturbative expansion of a solution, where the winding number of a vortex is naturally extended to be a real number and the solution is expanded with respect to it around its origin. We test this idea on three typical constants contained in the solution and confirm that this expansion works well with the help of the Pad\\'e approximation. For instance, we analytically reproduce the value of the scalar charge of the vortex with an error of $O(10^{-6})$. This expansion is also powerful even for large winding numbers.
Exploiting lens aberrations to create electron vortex beams
L. Clark; A. Béché; G. Guzzinati; A. Lubk; M. Mazilu; R. Van Boxem; J. Verbeeck
2013-07-18
A model for a new electron vortex beam production method is proposed and experimentally demonstrated. The technique calls on the controlled manipulation of the degrees of freedom of the lens aberrations to achieve a helical phase front. These degrees of freedom are accessible by using the corrector lenses of a transmission electron microscope. The vortex beam is produced through a particular alignment of these lenses into a specifically designed astigmatic state and applying an annular aperture in the condensor plane. Experimental results are found to be in good agreement with simulations.
Diego Julio Cirilo-Lombardo
2015-06-05
The 2-dimensional charge transport with parallel (in plane) magnetic field is considered from the physical and mathematical point of view. To this end, we start with the magnetic field parallel to the plane of charge transport, in sharp contrast to the configuration described by the theorems of Aharonov and Casher where the magnetic field is perpendicular. We explicitly show that the specific form of the arising equation enforce the respective field solution to fulfil the Majorana condition. Consequently, as soon any physical system is represented by this equation, the rise of fields with Majorana type behaviour is immediately explained and predicted. In addition, there exists a quantized particular phase that removes the action of the vector potential producing interesting effects. Such new effects are able to explain due the geometrical framework introduced, several phenomenological results recently obtained in the area of spintronics and quantum electronic devices. The quantum ring as spin filter is worked out in this framework and also the case of the quantum Hall effect.
Koochesfahani, Manoochehr M.
of confined flows such as vortex chambers, and swirl separators (e.g., hydrocyclones). More recently
Furuya, Ray S.; Kitamura, Yoshimi; Shinnaga, Hiroko E-mail: kitamura@isas.jaxa.jp
2014-10-01
To study physical properties of the natal filament gas around the cloud core harboring an exceptionally young low-mass protostar GF 9-2, we carried out J = 1-0 line observations of {sup 12}CO, {sup 13}CO, and C{sup 18}O molecules using the Nobeyama 45 m telescope. The mapping area covers ? one-fifth of the whole filament. Our {sup 13}CO and C{sup 18}O maps clearly demonstrate that the core formed at the local density maxima of the filament, and the internal motions of the filament gas are totally governed by turbulence with Mach number of ?2. We estimated the scale height of the filament to be H = 0.3-0.7 pc, yielding the central density of n {sub c} = 800-4200 cm{sup –3}. Our analysis adopting an isothermal cylinder model shows that the filament is supported by the turbulent and magnetic pressures against the radial and axial collapse due to self-gravity. Since both the dissipation timescales of the turbulence and the transverse magnetic fields can be comparable to the free-fall time of the filament gas of 10{sup 6} yr, we conclude that the local decay of the supersonic turbulence and magnetic fields made the filament gas locally unstable, hence making the core collapse. Furthermore, we newly detected a gas condensation with velocity width enhancement to ?0.3 pc southwest of the GF 9-2 core. The condensation has a radius of ?0.15 pc and an LTE mass of ?5 M {sub ?}. Its internal motion is turbulent with Mach number of ?3, suggesting a gravitationally unbound state. Considering the uncertainties in our estimates, however, we propose that the condensation is a precursor of a cloud core, which would have been produced by the collision of the two gas components identified in the filament.
Elliptic vortex patches: coasts and chaos Andrew Crosby
Lebovitz, Norman
are important for the transport of heat/salt across the Atlantic and, due to their relatively long life-times (O of such ocean vortices as point vortices and analysing their paths around islands or past coastal gaps presented by Ted were that of motion around a pair of islands (see Figure 2a) where the vortex patch might
Vortex Rings in a Stratified Fluid M. M. Scase
Dalziel, Stuart
in a stratified fluid, are developed. These models include both buoyancy forces and the drag due to the generation to investigate the waves generated by the propagation of the vortex ring, the ring is modelled as a sphere, based for describing these wavefronts is given. The drag due to the generated internal wave field is calculated
Modified Black Hole with Polar Jet and Vortex
T. Tmmalm
2001-12-06
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.
MOI OF PATTERN FORMATION IN THE VORTEX LANDSCAPE
Wijngaarden, Rinke J.
1081, 1081 HV Amsterdam, The Netherlands RW@NAT.VU.NL Abstract Due to the occurence of punctuations front were reported by Surdeanu et al.[1]. To local vortex density in the type-II YBa2Cu3O7
Numerical Approximation of Vortex Density Evolution in a Superconductor.
Styles, Vanessa
Numerical Approximation of Vortex Density Evolution in a Superconductor. C.M. Elliott & V. Styles Abstract A #12;nite volume/element approximation of a mean #12;eld model of superconducting vortices in one approximations of a two-dimensional version of the mean #12;eld model of superconducting vortices considered
Planet Embryos in Vortex Wombs Joseph A. Barranco
Marcus, Philip S.
Planet Embryos in Vortex Wombs Joseph A. Barranco and Philip S. Marcus Dept. of Astronomy gravitating planetesimals, the "build- ing blocks" of planets. One theory is that the dust grains settle into the mid-plane of the protoplane- tary disk (thin, cool disk of gas and dust in orbit around a newly
Biomedical Engineering Correlation Between Vortex Ring Formation and Mitral
Kheradvar, Arash
was generated during fluid propulsion and that it is maximal for an annulus diameter close to the normal adult typically develop from a jet or slug of fluid ejected from a nozzle. In fluid mechanics, mitral inflow fluid phenomena observed in the left ventricle during diastole is the presence of vortex rings
Vortex stabilized electron beam compressed fusion grade plasma
Hershcovitch, Ady
2014-03-19
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.
VORTEX: Design and Implementation of an Interactive Volumetric Display
Subramanian, Sriram
VORTEX: Design and Implementation of an Interactive Volumetric Display Abstract True 3D display systems like volumetric displays allow generation of autostereoscopic, multi-view 3D content that has real custom volumetric display from easily available components. By building a touch-enabled volumetric
Magnetic Braids Anthony Yeates
Dundee, University of
function Main result Conclusion Examples 1. Magnetic loops in the solar corona. NASA Solar Dynamics of the potential a Hi,j a x = 2 a xi At each neutral p Hi,j a . The magnet function and it co field topology. Magnetic helicity H = V AÂ·BdV, B = Ã?A is a well-known global ideal invariant in a closed
Hampshire, Damian
Numerical studies on the effect of normal-metal coatings on the magnetization characteristics; published 19 April 2005 Magnetic properties of superconductors coated with metals of arbitrary resistivity N in the coating is reduced, the initial vortex penetration field Hp N does not decrease monotonically from
Magnetic nano-particles | The Ames Laboratory
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverseIMPACTThousandReport) |Administration SavannahMagneticMagnetic Vortex
The chiral magnetic nanomotors
Morozov, Konstantin I
2013-01-01
Propulsion of the chiral magnetic nanomotors powered by a rotating magnetic field is in the focus of the modern biomedical applications. This technology relies on strong interaction of dynamic and magnetic degrees of freedom of the system. Here we study in detail various experimentally observed regimes of the helical nanomotor orientation and propulsion depending on the actuation frequency, and establish the relation of these two properties with remanent magnetization and geometry of the helical nanomotors. The theoretical predictions for the transition between the regimes and nanomotor orientation and propulsion speed are in excellent agreement with available experimental data. The proposed theory offers a few simple guidelines towards the optimal design of the magnetic nanomotors. In particular, efficient nanomotors should be fabricated of hard magnetics, e.g., cobalt, magnetized transversally and have the geometry of a normal helix with a helical angle of 35-45 degrees.
Archontis, V.; Hood, A. W.; Tsinganos, K.
2014-05-10
We report on three-dimensional MHD simulations of recurrent mini coronal mass ejection (CME)-like eruptions in a small active region (AR), which is formed by the dynamical emergence of a twisted (not kink unstable) flux tube from the solar interior. The eruptions develop as a result of the repeated formation and expulsion of new flux ropes due to continuous emergence and reconnection of sheared field lines along the polarity inversion line of the AR. The acceleration of the eruptions is triggered by tether-cutting reconnection at the current sheet underneath the erupting field. We find that each explosive eruption is followed by reformation of a sigmoidal structure and a subsequent ''sigmoid-to-flare arcade'' transformation in the AR. These results might have implications for recurrent CMEs and eruptive sigmoids/flares observations and theoretical studies.
Pressurized water nuclear reactor system with hot leg vortex mitigator
Lau, Louis K. S. (Monroeville, PA)
1990-01-01
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.
Super Stability of Laminar Vortex Flow in Superfluid 3He-B
V. B. Eltsov; R. de Graaf; P. J. Heikkinen; J. J. Hosio; R. Hanninen; M. Krusius; V. S. L'vov
2010-05-04
Vortex flow remains laminar up to large Reynolds numbers (Re~1000) in a cylinder filled with 3He-B. This is inferred from NMR measurements and numerical vortex filament calculations where we study the spin up and spin down responses of the superfluid component, after a sudden change in rotation velocity. In normal fluids and in superfluid 4He these responses are turbulent. In 3He-B the vortex core radius is much larger which reduces both surface pinning and vortex reconnections, the phenomena, which enhance vortex bending and the creation of turbulent tangles. Thus the origin for the greater stability of vortex flow in 3He-B is a quantum phenomenon. Only large flow perturbations are found to make the responses turbulent, such as the walls of a cubic container or the presence of invasive measuring probes inside the container.
Highly efficient electron vortex beams generated by nanofabricated phase holograms
Grillo, Vincenzo; Mafakheri, Erfan; Frabboni, Stefano
2014-01-27
We propose an improved type of holographic-plate suitable for the shaping of electron beams. The plate is fabricated by a focused ion beam on a silicon nitride membrane and introduces a controllable phase shift to the electron wavefunction. We adopted the optimal blazed-profile design for the phase hologram, which results in the generation of highly efficient (25%) electron vortex beams. This approach paves the route towards applications in nano-scale imaging and materials science.
Vortex energy and 360 Neel walls in thinfilm
.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
Vortex energy and 360 Neel wall in thinfilm
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
Krakauer, Henry; Zhang, Shiwei
2013-02-21
There are classes of materials that are important to DOE and to the science and technology community, generically referred to as strongly correlated electron systems (SCES), which have proven very difficult to understand and to simulate in a material-specific manner. These range from actinides, which are central to the DOE mission, to transition metal oxides, which include the most promising components of new spin electronics applications as well as the high temperature superconductors, to intermetallic compounds whose heavy fermion characteristics and quantum critical behavior has given rise to some of the most active areas in condensed matter theory. The objective of the CMSN cooperative research team was to focus on the application of these new methodologies to the specific issue of Mott transitions, multi-electron magnetic moments, and dynamical properties correlated materials. Working towards this goal, the W&M team extended its first-principles phaseless auxiliary-field quantum Monte Carlo (AFQMC) method to accurately calculate structural phase transitions and excited states.
Equilibrium vortex motion in two- and three-dimensional suprconductors studied with a dc SQUID
Shaw, Timothy J.
2010-01-01
is determined by thermal activation between pinning sites.is determined by thermal activation, it is important tothe SQUID washer. Thermal activation of the vortex between
Hummingbirds generate bilateral vortex loops during hovering: evidence from flow visualization
Pournazeri, Sam; Segre, Paolo; Princevac, Marko; Altshuler, Douglas
2012-01-01
energetic cost of flight (Rayner and Gordon 1998; Hedenstro¨generates one vortex ring per stroke (Rayner 1979; Ellington1984; Pennycuick 1988; Rayner and Gordon 1998), which would
Sbitnev, Valeriy I
2014-01-01
Owing to three conditions (namely: (a) the velocity is represented by sum of irrotational and solenoidal components; (b) the fluid is barotropic; (c) a bath with the fluid undergoes vertical vibrations) the Navier-Stokes equation admits reduction to the modified Hamilton-Jacobi equation. The modification term is the Bohmian(quantum) potential. This reduction opens possibility to define a complex-valued function, named the wave function, which is a solution of the Schr\\"{o}dinger equation. The solenoidal component being added to the momentum operator poses itself as a vector potential by analogy with the magnetic vector potential. The vector potential is represented by the solenoidal velocity multiplied by mass of the fluid element. Vortex tubes, rings, and balls along with the wave function guiding these objects are solutions of this equation. Motion of the vortex balls along the Bohmian trajectories gives a model of droplets moving on the fluid surface. A peculiar fluid is the superfluid physical vacuum. It ...
Chu, Shih-I
in crossed magnetic and electric fields Xiao-Min Tong and Shih-I Chu Department of Chemistry, University time-dependent study of three- dimensional Rydberg H atoms in crossed magnetic and electric fields magnetic and electric fields has attracted considerable attention in the last several years both
Masaaki Yamada, Russell Kulsrud and Hantao Ji
2009-09-17
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.
Vortex-induced vibration of a circular cylinder with combined in-line and cross-flow motion
Dahl, Jason (Jason Michael)
2008-01-01
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 ...
Generation of a spin-polarized electron beam by multipole magnetic fields
Boyd, Robert W.
Generation of a spin-polarized electron beam by multipole magnetic fields Ebrahim Karimi a October 2013 Accepted 18 December 2013 Available online 31 December 2013 Keywords: Electron vortex beam Polarized electron beam Spin-to-orbit conversion a b s t r a c t The propagation of an electron beam
T. D. Andersen; C. C. Lim
2008-02-29
Negative specific heat is a dramatic phenomenon where processes decrease in temperature when adding energy. It has been observed in gravo-thermal collapse of globular clusters. We now report finding this phenomenon in bundles of nearly parallel, periodic, single-sign generalized vortex filaments in the electron magnetohydrodynamic (EMH) model for the unbounded plane under strong magnetic confinement. We derive the specific heat using a steepest descent method and a mean field property. Our derivations show that as temperature increases, the overall size of the system increases exponentially and the energy drops. The implication of negative specific heat is a runaway reaction, resulting in a collapsing inner core surrounded by an expanding halo of filaments.
Lin, Yu-Chun [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China) [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Department of Electrical Engineering, Chang Gung University, Linkou, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Wang, Jiun-Jie [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China) [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Hong, Ji-Hong [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China) [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Lin, Yi-Ping [Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China)] [Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Lee, Chung-Chi [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China) [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Wai, Yau-Yau; Ng, Shu-Hang; Wu, Yi-Ming [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China) [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Taiwan (China); Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Wang, Chun-Chieh, E-mail: jjwang@adm.cgmh.org.tw [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China) [Department of Medical Imaging and Radiological Sciences, Chang Gung University, Linkou, Taiwan (China); Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou, Taiwan (China)
2013-04-01
Purpose: The microvasculature of a tumor plays an important role in its response to radiation therapy. Dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) and blood oxygen level-dependent (BOLD) MRI are both sensitive to vascular characteristics. The present study proposed a partial irradiation approach to a xenograft tumor to investigate the intratumoral response to radiation therapy using DCE and BOLD MRI. Methods and Materials: TRAMP-C1 tumors were grown in C57BL/6J mice. Partial irradiation was performed on the distal half of the tumor with a single dose of 15 Gy. DCE MRI was performed to derive the endothelium transfer constant, K{sup trans}, using pharmacokinetic analysis. BOLD MRI was performed using quantitative R2* measurements with carbogen breathing. The histology of the tumor was analyzed using hematoxylin and eosin staining and CD31 staining to detect endothelial cells. The differences between the irradiated and nonirradiated regions of the tumor were assessed using K{sup trans} values, ?R2* values in response to carbogen and microvascular density (MVD) measurements. Results: A significantly increased K{sup trans} and reduced BOLD response to carbogen were found in the irradiated region of the tumor compared with the nonirradiated region (P<.05). Histologic analysis showed a significant aggregation of giant cells and a reduced MVD in the irradiated region of the tumor. The radiation-induced difference in the BOLD response was associated with differences in MVD and K{sup trans}. Conclusions: We demonstrated that DCE MRI and carbogen-challenge BOLD MRI can detect differential responses within a tumor that may potentially serve as noninvasive imaging biomarkers to detect microvascular changes in response to radiation therapy.
Heyerdahl, Helen; Røe, Kathrine; Brevik, Ellen Mengshoel; Dahle, Jostein
2013-09-01
Purpose: The purpose of this study was to investigate the effect of ?-particle-emitting {sup 227}Th-trastuzumab radioimmunotherapy on tumor vasculature to increase the knowledge about the mechanisms of action of {sup 227}Th-trastuzumab. Methods and Materials: Human HER2-expressing SKOV-3 ovarian cancer xenografts were grown bilaterally in athymic nude mice. Mice with tumor volumes 253 ± 36 mm{sup 3} (mean ± SEM) were treated with a single injection of either {sup 227}Th-trastuzumab at a dose of 1000 kBq/kg body weight (treated group, n=14 tumors) or 0.9% NaCl (control group, n=10 tumors). Dynamic T1-weighted contrast-enhanced magnetic resonance imaging (DCEMRI) was used to study the effect of {sup 227}Th-trastuzumab on tumor vasculature. DCEMRI was performed before treatment and 1, 2, and 3 weeks after therapy. Tumor contrast-enhancement curves were extracted voxel by voxel and fitted to the Brix pharmacokinetic model. Pharmacokinetic parameters for the tumors that underwent radioimmunotherapy were compared with the corresponding parameters of control tumors. Results: Significant increases of k{sub ep}, the rate constant of diffusion from the extravascular extracellular space to the plasma (P<.05), and k{sub el,} the rate of clearance of contrast agent from the plasma (P<.01), were seen in the radioimmunotherapy group 2 and 3 weeks after injection, compared with the control group. The product of k{sub ep} and the amplitude parameter A, associated with increased vessel permeability and perfusion, was also significantly increased in the radioimmunotherapy group 2 and 3 weeks after injection (P<.01). Conclusions: Pharmacokinetic modeling of MRI contrast-enhancement curves evidenced significant alterations in parameters associated with increased tumor vessel permeability and tumor perfusion after {sup 227}Th-trastuzumab treatment of HER2-expressing ovarian cancer xenografts.
Corley, Richard A.; Minard, Kevin R.; Kabilan, Senthil; Einstein, Daniel R.; Kuprat, Andrew P.; harkema, J. R.; Kimbell, Julia; Gargas, M. L.; Kinzell, John H.
2009-06-01
The percentages of total air?ows over the nasal respiratory and olfactory epithelium of female rabbits were cal-culated from computational ?uid dynamics (CFD) simulations of steady-state inhalation. These air?ow calcula-tions, along with nasal airway geometry determinations, are critical parameters for hybrid CFD/physiologically based pharmacokinetic models that describe the nasal dosimetry of water-soluble or reactive gases and vapors in rabbits. CFD simulations were based upon three-dimensional computational meshes derived from magnetic resonance images of three adult female New Zealand White (NZW) rabbits. In the anterior portion of the nose, the maxillary turbinates of rabbits are considerably more complex than comparable regions in rats, mice, mon-keys, or humans. This leads to a greater surface area to volume ratio in this region and thus the potential for increased extraction of water soluble or reactive gases and vapors in the anterior portion of the nose compared to many other species. Although there was considerable interanimal variability in the ?ne structures of the nasal turbinates and air?ows in the anterior portions of the nose, there was remarkable consistency between rabbits in the percentage of total inspired air?ows that reached the ethmoid turbinate region (~50%) that is presumably lined with olfactory epithelium. These latter results (air?ows reaching the ethmoid turbinate region) were higher than previous published estimates for the male F344 rat (19%) and human (7%). These di?erences in regional air?ows can have signi?cant implications in interspecies extrapolations of nasal dosimetry.
Laminar Flow of a Sheared Vortex Crystal: Scars in Flat Geometry M.-Carmen Miguel,1
Miguel-Lopez, Carmen
Laminar Flow of a Sheared Vortex Crystal: Scars in Flat Geometry M.-Carmen Miguel,1 Adil Mughal,2 November 2010; published 15 June 2011) We consider the laminar flow of a vortex crystal in the Corbino disk geometry. Laminar flow can be induced by thermal fluctuations melting the crystal, but also by shear stress
Resuspension onset and crater erosion by a vortex ring interacting with a particle layer
Dalziel, Stuart
Resuspension onset and crater erosion by a vortex ring interacting with a particle layer N. Bethke. Fluids 24, 055106 (2012) Conveyor belt effect in the flow through a tube of a viscous fluid with spinning and crater erosion by a vortex ring interacting with a particle layer N. Bethkea) and S. B. Dalziel
Impact of vortex core structure on equftion of motion V.A.Budarin
1 Impact of vortex core structure on equftion of motion V.A.Budarin National Polytechnical-solid hollow and continuous vortex core wall has been examined in this paper. Two other exact solutions derived of thick-walled cylinders and task about the tube rotation. Comparison of the results obtained has been
Mixing characteristics of compressible vortex rings interacting with normal shock waves
Cetegen, B.M. . Mechanical Engineering Dept.); Hermanson, J.C. )
1995-01-01
Current interest in the interaction between compressible vortical flows and shock waves is largely motivated by the need to promote rapid, loss-effective mixing and combustion of hydrogen and hydrocarbon fuels for supersonic combustor applications. The instability mechanisms and mixing enhancement arising from the interaction of a compressible vortex ring with a normal shock wave were studied in a colinear, dual-shock tube. This flow geometry simulates features of the interaction of a shock wave with a jet containing streamwise vorticity, a configuration of significant interest for supersonic combustion applications. Flow visualization and quantitative concentration measurements were performed by planar laser Rayleigh scattering. For a given primary shock strength, interfacial instability is more evident in a weak vortex ring than in a strong vortex ring. In all cases, the identity of the vortex ring is lost after a sufficiently long time of interaction. The probability density function of the mixed fluid changes rapidly from a bimodal distribution to a single peak upon processing by a shock wave. The most probable concentration decreases with time, indicating a rapid increase in mixing and dilution of the vortex fluid. The mixing enhancement is most rapid for the case of a strong vortex ring interacting with a strong shock wave, somewhat slower for a weak vortex ring and a strong shock wave, and significantly slower for the case of a strong vortex ring and a weaker shock wave. These observations are consistent with the earlier numerical predictions.
Comparison of optical vortex detection methods for use with a Shack-Hartmann
Dainty, Chris
Comparison of optical vortex detection methods for use with a Shack-Hartmann wavefront sensor Kevin of de- tecting optical vortices from Shack-Hartmann wavefront sensor (SHWFS) data, the vortex potential of Shack-Hartmann wavefront sensing," J. Refract. Surg. 17, S573ÂS577 (2001). 13. J. Notaras and C
A Model of Compressor Blade Row Interaction with Shock Induced Vortex Shedding
Cincinnati, University of
A Model of Compressor Blade Row Interaction with Shock Induced Vortex Shedding Mark G. Turner". The mid and far spacings represent typical axial gaps found in operational fans and compressors. However behind a stator are modeled. The model is based on a Burger vortex core model for shed vortices
Numerical Simulation of Vortex Pyrolysis Reactors for Condensable Tar Production from Biomass
Miller, Richard S.
Numerical Simulation of Vortex Pyrolysis Reactors for Condensable Tar Production from Biomass R. S is performed in order to evaluate the performance and optimal operating conditions of vortex pyrolysis reactors particle pyrolysis is coupled with a compressible Reynolds stress transport model for the turbulent reactor
Nanogenerator as an active sensor for vortex capture and ambient wind-velocity detection
Wang, Zhong L.
efficiently convert the vortex motion in the atmosphere into electricity. Based on the Karman vortex street in wireless environmental monitoring networks. 1. Introduction Self-powered nanosystem is a promising concept for the realization of environmental wireless sensor networks. Due to the enormous demands of distributed nodes
The critical velocity for vortex existence in a two dimensional rotating Bose-Einstein condensate
Ignat, Radu
The critical velocity for vortex existence in a two dimensional rotating Bose-Einstein condensate-Einstein condensate. It consists in minimizing a Gross-Pitaevskii functional defined in R2 under the unit mass constraint. We estimate the critical rotational speed 1 for vortex existence in the bulk of the condensate
Generalized London free energy for high-Tc vortex lattices Ian Affleck
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
A model for universal time scale of vortex ring formation Kamran Mohseni
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
Apte, Sourabh V.
Modeling bubble-vortex interactions Modeling and simulation of multiple bubble entrainment entrainment and interactions with two dimensional vorti- cal flows are preformed using a Discrete Element microbubbles entrained in a traveling vortex tube is studied in detail. The test case resembles the experiments
-point motion in a d-wave superconductor. The vortex is treated as a point flux tube, carrying fluxElectronic states near a quantum fluctuating point vortex in a d-wave superconductor: Dirac fermion model of the low-energy electronic states in the vicinity of a vortex undergoing quantum zero
Bolster, Diogo
, at least for a straight vortex tube case, results from subjection to a straining field in a planeSlowing of vortex rings by development of Kelvin waves Robert E. Hershberger, Diogo Bolster the slowing of viscous vortex rings. In particular we do so using the concept of drag coefficient, which
Nelson, Robert C.
. Helium bubbles were introduced into the core region of individual vortices to visualize these wake. These results suggest that the use of helium bubbles is a suitable method for visualizing wake vortices programs can be divided into two categories, vortex detection and vortex alleviation. The vortex detection
Vortex nozzle for segmenting and transporting metal chips from turning operations
Bieg, L.F.
1993-04-20
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.
Seymour, P.
1986-01-01
This book deals with the cosmic magnetism in a non-mathematical way. It uses Faraday's very powerful and highly pictorial concept of lines of magnetic force and their associated physical properties to explain the structure and behavior of magnetic fields in extraterrestrial objects. Contents include: forces of nature; magnetic field of earth; solar and interplanetary magnetic fields; magnetic fields in the solar system; stars and pulsars; and magnetic fields of the milky way and other galaxies.
The Relation Between Dry Vortex Merger and Tropical Cyclone Genesis over the Atlantic Ocean
Chen, Shu-Hua; Liu, Yi-Chin
2014-10-27
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.
Venturi/vortex technology for controlling chromium electroplating emissions
Hay, K.J.; Northrup, J. [Army Construction Engineering Research Labs., Champaign, IL (United States); Heck, S.R. [MSE-HKM, Inc., Butte, MT (United States)
1997-12-31
A new technology has been developed to control air emissions from hexavalent chromium electroplating tanks. The venturi/vortex scrubber uses a patented drain assembly to pull plating solution, air with toxic particulates above the solution, and unpopped bubbles of generated gases down with a gravity generated vortex effect. The recirculated plating solution acts as the scrubbing liquid and air agitation is eliminated. Separated gases are passed through a condenser/filter to remove any remaining fumes. The device is almost entirely constructed of CPVC. This device offers several advantages over conventional end-of-pipe systems including significantly lower cost, no wastewater, no extensive ventilation system, and emissions are recycled. The system can be is easily retrofitted to existing tanks, however, a loose fitting tank lid is recommended. A pilot demonstration has been performed at Benet Laboratory, Watervliet, NY (US Army) with a 1,500 gallon chromic acid electroplating tank and 1,500 Amps of applied current. Overall chromium emissions results were 0.00002 mg/Amp-hr, surpassing the stringent California State requirement of 0.006 mg/Amp-hr. Emission prevention by capturing unpopped bubbles is the method in which this system reduces the most emissions. The system met current ambient worker safety standards. Two major improvements are recommended: an increase in gas flow rate through the system and a solution to the system`s sensitivity to the plating solution level.
Canonical equations of ideal magnetic hydrodynamics
Gorskii, V.B.
1987-07-01
Ideal magnetohydrodynamics is used to consider a general class of adiabatic flow in magnetic liquids. Two invariants of the canonical equations of motion--Hamiltonian and Lagrangian--are determined in terms of the canonical variables by using the approximate variational formulations. The resulting model describes adiabatic three-dimensional flow of a nonviscous compressible liquid with ideal electric conductivity and zero heat conductivity. A Clebsch transformation is used to arrive at a form of the Lagrange-Cauchy integral for a vortex flow.
Theory of static and dynamic antiferromagnetic vortices in LSCO superconductors
Hu, Jiangping
Theory of static and dynamic antiferromagnetic vortices in LSCO superconductors Jiang-Ping Hu, Shou. Here we review theoretical progress since the original proposal and present a theory of static experimental definition of the AFVS, where static AF order coexists with the vortex state of the superconductor
Vortex Diode Analysis and Testing for Fluoride Salt-Cooled High-Temperature Reactors
Yoder Jr, Graydon L [ORNL; Elkassabgi, Yousri M. [Texas A& M University, Kingsville; De Leon, Gerardo I. [Texas A& M University, Kingsville; Fetterly, Caitlin N. [Texas A& M University, Kingsville; Ramos, Jorge A. [Texas A& M University, Kingsville; Cunningham, Richard Burns [University of Tennessee, Knoxville (UTK)
2012-02-01
Fluidic diodes are presently being considered for use in several fluoride salt-cooled high-temperature reactor designs. A fluidic diode is a passive device that acts as a leaky check valve. These devices are installed in emergency heat removal systems that are designed to passively remove reactor decay heat using natural circulation. The direct reactor auxiliary cooling system (DRACS) uses DRACS salt-to-salt heat exchangers (DHXs) that operate in a path parallel to the core flow. Because of this geometry, under normal operating conditions some flow bypasses the core and flows through the DHX. A flow diode, operating in reverse direction, is-used to minimize this flow when the primary coolant pumps are in operation, while allowing forward flow through the DHX under natural circulation conditions. The DRACSs reject the core decay heat to the environment under loss-of-flow accident conditions and as such are a reactor safety feature. Fluidic diodes have not previously been used in an operating reactor system, and therefore their characteristics must be quantified to ensure successful operation. This report parametrically examines multiple design parameters of a vortex-type fluidic diode to determine the size of diode needed to reject a particular amount of decay heat. Additional calculations were performed to size a scaled diode that could be tested in the Oak Ridge National Laboratory Liquid Salt Flow Loop. These parametric studies have shown that a 152.4 mm diode could be used as a test article in that facility. A design for this diode is developed, and changes to the loop that will be necessary to test the diode are discussed. Initial testing of a scaled flow diode has been carried out in a water loop. The 150 mm diode design discussed above was modified to improve performance, and the final design tested was a 171.45 mm diameter vortex diode. The results of this testing indicate that diodicities of about 20 can be obtained for diodes of this size. Experimental results show similar trends as the computational fluid dynamics (CFD) results presented in this report; however, some differences exist that will need to be assessed in future studies. The results of this testing will be used to improve the diode design to be tested in the liquid salt loop system.
Dynamics of a global string with large Higgs boson mass
C. Charmousis; B. Boisseau; B. Linet
1998-01-12
We consider a self-gravitating string generated by a global vortex solution in general relativity. We investigate the Einstein and field equations of a global vortex in the region of its central line and at a distance from the centre of the order of the inverse of its Higgs boson mass. By combining the two we establish by a limiting process of large Higgs mass the dynamics of a self-gravitating global string. Under our assumptions the presence of gravitation restricts the world sheet of the global string to be totally geodesic.
ASSESSMENT OF WAKE VORTEX SEPARATION DISTANCES USING THE WAVIR TOOLSET
) and Failure Modes and Effects Analysis (FMEA), are not easily applied due the dynamic stochastic nature
Vortex flow in the technology of radiation wave cracking (RWC)
L. A. Tsoy; V. N. Kolushov; A. G. Komarov; A. N. Tsoy
2012-09-16
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.
Stabilization of three-wave vortex beams in the waveguide
Gammal, Arnaldo
2015-01-01
We consider two-dimensional (2D) localized vortical modes in the three-wave system with the quadratic ($\\chi ^{(2)}$) nonlinearity, alias nondegenerate second-harmonic-generating system, guided by the isotropic harmonic-oscillator (HO) (alias parabolic) confining potential. In addition to the straightforward realization in optics, the system models mixed atomic-molecular Bose-Einstein condensates (BECs). The main issue is stability of the vortex modes, which is investigated through computation of instability growth rates for eigenmodes of small perturbations, and by means of direct simulations. The threshold of parametric instability for single-color beams, represented solely by the second harmonic (SH) with zero vorticity, is found in an analytical form with the help of the variational approximation (VA). Trapped states with vorticities $\\left( +1,-1,0\\right) $ in the two fundamental-frequency (FF) components and the SH one [the so-called \\textit{hidden-vorticity} (HV) modes] are completely unstable. Also un...
Gas turbine engine combustor can with trapped vortex cavity
Burrus, David Louis; Joshi, Narendra Digamber; Haynes, Joel Meier; Feitelberg, Alan S.
2005-10-04
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.
Vortex Induced Vibrations of cylinders : experiments in reducing drag force and amplitude of motion
Farrell, David Emmanuel
2007-01-01
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 ...
Numerically-based ducted propeller design using vortex lattice lifting line theory
Stubblefield, John M
2008-01-01
This thesis used vortex lattice lifting line theory to model an axisymmetrical-ducted propeller with no gap between the duct and the propeller. The theory required to model the duct and its interaction with the propeller ...
An adaptive mesh method for the simulation of Blade Vortex Interaction
Kim, Kyu-Sup
1998-01-01
An adaptive mesh method for the simulation of parallel ics. Blade Vortex Interaction (BV1) with an active Trailing Edge Flap (TEF) is presented. The two-dimensional 1111-steady problem is solved by a higher order upwind Euler method...
Variability of the polar stratospheric vortex and its impact on surface climate patterns
Sheshadri, Aditi
2015-01-01
This thesis investigates various aspects of the variability of the stratospheric polar vortex and the effect of this variability on tropospheric weather and climate patterns on various timescales. In the first part of this ...
Reduced gravity rankine cycle design and optimization with passive vortex phase separation
Supak, Kevin Robert
2009-05-15
turbo machinery, require kilowatts of power and are untested for high vapor flow conditions. The Interphase Transport Phenomena (ITP) laboratory has developed a low-power, passive microgravity vortex phase separator (MVS) which has already proven...
Effect of traveling waves on Vortex-Induced Vibration of long flexible cylinders
Jaiswal, Vivek, Ph. D. Massachusetts Institute of Technology
2009-01-01
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 ...
Vortex-induced vibration of flexible cylinders in time-varying flows
Resvanis, Themistocles L
2014-01-01
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 ...
Enhancement of vortex induced forces and motion through surface roughness control
Bernitsas, Michael M. (Saline, MI); Raghavan, Kamaldev (Houston, TX)
2011-11-01
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).
Explicit mean-field radius for nearly parallel vortex filaments in statistical equilibrium
Timothy D. Andersen; Chjan C. Lim
2006-11-19
Geophysical research has focused on flows, such as ocean currents, as two dimensional. Two dimensional point or blob vortex models have the advantage of having a Hamiltonian, whereas 3D vortex filament or tube systems do not necessarily have one, although they do have action functionals. On the other hand, certain classes of 3D vortex models called nearly parallel vortex filament models do have a Hamiltonian and are more accurate descriptions of geophysical and atmospheric flows than purely 2D models, especially at smaller scales. In these ``quasi-2D'' models we replace 2D point vortices with vortex filaments that are very straight and nearly parallel but have Brownian variations along their lengths due to local self-induction. When very straight, quasi-2D filaments are expected to have virtually the same planar density distributions as 2D models. An open problem is when quasi-2D model statistics behave differently than those of the related 2D system and how this difference is manifested. In this paper we study the nearly parallel vortex filament model of Klein, Majda, Damodaran in statistical equilibrium. We are able to obtain a free-energy functional for the system in a non-extensive thermodynamic limit that is a function of the mean square vortex position $R^2$ and solve \\emph{explicitly} for $R^2$. Such an explicit formula has never been obtained for a non-2D model. We compare the results of our formula to a 2-D formula of \\cite{Lim:2005} and show qualitatively different behavior even when we disallow vortex braiding. We further confirm our results using Path Integral Monte Carlo (Ceperley (1995)) \\emph{without} permutations and that the Klein, Majda, Damodaran model's asymptotic assumptions \\emph{are valid} for parameters where these deviations occur.
Vortex in a weakly relativistic Bose gas at zero temperature and relativistic fluid approximation
B. Boisseau
2004-09-14
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.
Resonant amplification of vortex-core oscillations by coherent magnetic-field pulses
Yu, Young-Sang
2014-01-01
2002). 41. Cowburn, R. P. Spintronics: Change of direction.Past achievements in spintronics have largely relied on an
Smith, Kevin Daniel
2008-01-01
penetration through the superconductive film as it relatesThus, to sustain superconductivity throughout the materialthe mixed state, type-II superconductors have characteristic
California at San Diego, University of
Plasma Columns A dissertation submitted in partial satisfaction of the requirements for the degree Doctor. Images of vorticity at five times for two sequences from similar initial conditions. The red arcs
Smith, Kevin Daniel
2008-01-01
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.
Creation and pinning of vortex-antivortex pairs
Kim, Sangbum; Hu, Chia-Ren; Andrews, Malcolm J.
2006-01-01
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. For film thickness =0.1 xi, kappa=2, and no pins, we find the film carries two V-AV pairs at steady state...
Shaw, Leah B.
-TC superconductors. The focus of our research is on dynamical processes (electronic, magnetic, and vibrational
Model for characterization of a vortex pair formed by shock passage over a light-gas inhomogeneity
Yang, J.; Kubota, T.; Zukoski, E.E.
1994-01-01
This work investigates the two-dimensional flow of a shock wave over a circular light-gas inhomogeneity in a channel with finite width. The pressure gradient from the shock wave interacts with the density gradient at the edge of the inhomogeneity to deposit vorticity around the perimeter, and the structure rolls up into a pair of counter-rotating vortices. The aim of this study is to develop an understanding of the scaling laws for the flow field produced by this interaction at times long after the passage of the shock across the inhomogeneity. Numerical simulations are performed for various initial conditions and the results are used to guide the development of relatively simple algebraic models that characterize the dynamics of the vortex pair, and that allow extrapolation of the numerical results to conditions more nearly of interest in practical situations. The models are not derived directly from the equations of motion but depend on these equations and on intuition guided by the numerical results. Agreement between simulations and models is generally good except for a vortex-spacing model which is less satisfactory. A practical application of this shock-induced vortical flow is rapid and efficient mixing of fuel and oxidizer in a SCRAMJET combustion chamber. One possible injector design uses the interaction of an oblique shock wave with a jet of light fuel to generate vorticity which stirs and mixes the two fluids and lifts the burning jet away from the combustor wall. Marble proposed an analogy between this three-dimensional steady flow and the two-dimensional unsteady problem of the present investigation. Comparison is made between closely corresponding three-dimensional steady and two-dimensional unsteady flows, and a mathematical description of Marble`s analogy is proposed. 17 refs.
King, Andrew
2012-04-26
20 40 60 80 100 120 140 To ta l E ne rg y (e V ) Vortex-?Core Posi2on (nm) Total Energy vs. Vortex-?Core Posi2on 65 nm Diameter Iron Dot 0 kOe 0.5 kOe 17... B ar ri er (e V ) Applied Field (kOe) Energy Barriers vs. Applied Field 40 nm Diameter Iron Dot Vortex Annihila:on Vortex Nuclea:on 21 FIG. 8. Energy barriers plotted versus applied...
Pinning induced by inter-domain wall interactions in planar magnetic nanowires
Hayward, T.J.; Bryan, M.T.; Fry, P.W.; Fundi, P.M.; Gibbs, M.R.J.; Allwood, D.A.; Im, M.-Y.; Fischer, P.
2009-10-30
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.
Not Available
1994-08-01
This report discusses the following topics on superconducting magnets: D19B and -C: The next steps for a record-setting magnet; D20: The push beyond 10 T: Beyond D20: Speculations on the 16-T regime; other advanced magnets for accelerators; spinoff applications; APC materials development; cable and cabling-machine development; and high-{Tc} superconductor at low temperature.
Brian Niebergal; Rachid Ouyed; Rodrigo Negreiros; Fridolin Weber
2010-01-29
Compact stars made of quark matter rather than confined hadronic matter, are expected to form a color superconductor. This superconductor ought to be threaded with rotational vortex lines, within which the star's interior magnetic field is at least partially confined. The vortices (and thus magnetic flux) would be expelled from the star during stellar spin-down, leading to magnetic reconnection at the surface of the star and the prolific production of thermal energy. In this paper, we show that this energy release can re-heat quark stars to exceptionally high temperatures, such as observed for Soft Gamma Repeaters (SGRs), Anomalous X-Ray pulsars (AXPs), and X-ray dim isolated neutron stars (XDINs). Moreover, our numerical investigations of the temperature evolution, spin-down rate, and magnetic field behavior of such superconducting quark stars suggest that SGRs, AXPs, and XDINs may be linked ancestrally. Finally, we discuss the possibility of a time delay before the star enters the color superconducting phase, which can be used to estimate the density at which quarks deconfine. From observations, we find this density to be of the order of five times that of nuclear saturation.
Spontaneous vortex phase and pinning in ferromagnetic-superconducting systems
Kayali, Mohammad Amin
2004-09-30
of vortices is possible mostly in a close vicinity of the superconducting transition temperature Ts. For every case, the threshold value of the magnetization at which vortices start to be spontaneously created in the SC is calculated as a function...
Vortex generation in protoplanetary disks with an embedded giant planet
M. de Val-Borro; P. Artymowicz; G. D'Angelo; A. Peplinski
2007-06-21
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 $\
Coherent dynamics in the rotor tip shear layer of utility scale wind turbines
Yang, Xiaolei; Barone, Matthew; Sotiropoulos, Fotis
2015-01-01
Recent field experiments conducted in the near-wake (up to 0.5 rotor diameters downwind of the rotor) of a 2.5 MW wind turbine using snow-based super-large-scale particle image velocimetery (SLPIV) (Hong et al., Nature Comm., vol. 5, 2014, no. 4216) were successful in visualizing tip vortex cores as areas devoid of snowflakes. The so-visualized snow voids, however, suggested tip vortex cores of complex shape consisting of circular cores with distinct elongated comet-like tails. We employ large-eddy simulation (LES) to elucidate the structure and dynamics of the complex tip vortices identified experimentally. The LES is shown to reproduce vortex cores in good qualitative agreement with the SLPIV results, essentially capturing all vortex core patterns observed in the field in the tip shear layer. We show that the visualized vortex patterns are the result of energetic coherent dynamics in the rotor tip shear layer driven by interactions between the tip vortices and a second set of counter-rotating spiral vortice...
Kim, Sangbum
2006-04-12
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 ...
Dissolution Dynamic Nuclear Polarization of Polypeptides
Ragavan, Mukundan
2014-06-27
Nuclear Magnetic Resonance (NMR) spectroscopy provides remarkable site resolution, but often requires signal averaging because of low sensitivity. Dissolution dynamic nuclear polarization (DNP), which offers large signal ...
Magnetization reversal assisted by half antivortex states in nanostructured circular cobalt disks
Lara, A.; Aliev, F. G.; Dobrovolskiy, O. V.; Prieto, J. L.; Huth, M.
2014-11-03
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.
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
Cottet, Georges-Henri
in a non laminar flow. Here we consider a different approach. The fluid solid system is considered rights reserved. Keywords: Incompressible flow; Fluidsolid interaction; Vortex method; Level set methodA vortex level set method for the two-way coupling of an incompressible fluid with colliding rigid
Two-dimensional model problem to explain counter-rotating vortex pair formation in a transverse jet
Mahesh, Krishnan
Two-dimensional model problem to explain counter-rotating vortex pair formation in a transverse jet A two-dimensional model problem is used to study the evolution of the cross section of a transverse jet and the counter-rotating vortex pair CVP . The solution to the model problem shows deformation of the jet similar
Suryanarayanan, Saikishan
2015-01-01
The relevance of the vortex-gas model to the large scale dynamics of temporally evolving turbulent free shear layers in an inviscid incompressible fluid has recently been established by extensive numerical simulations (Suryanarayanan et al, Phys. Rev. E 89, 013009, 2014). Here, the effects of the velocity ratio across a spatially evolving 2D free shear layer are investigated by vortex-gas simulations, using a computational model based on Basu et al (1992, 1995), but with a crucial improvement that ensures conservation of global circulation. These are carried out for a range of values of the velocity ratio parameter $\\lambda= (U_1-U_2)/(U_1+U_2)$, where $U_1$ and $U_2$ ($< U_1$) are respective velocities across the layer. The simulations show that the conditions imposed at the beginning of the free shear layer and at the exit to the domain can affect the flow evolution in their respective neighborhoods, the latter being particularly strong as $\\lambda \\rightarrow 1$. In between the two neighborhoods is a re...
-wave superconductor. The vortex is treated as a point flux tube, carrying flux of an auxiliary U(1) gauge fieldarXiv:cond-mat/0606001v222Jul2006 Electronic states near a quantum fluctuating point vortex in a d energy electronic states in the vicinity of a vortex under- going quantum zero-point motion in a d
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
Vortex combustor for low NOx emissions when burning lean premixed high hydrogen content fuel
Steele, Robert C. (Woodinville, WA); Edmonds, Ryan G. (Renton, WA); Williams, Joseph T. (Kirkland, WA); Baldwin, Stephen P. (Winchester, MA)
2009-10-20
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.
Reduction of vortex induced forces and motion through surface roughness control
Bernitsas, Michael M; Raghavan, Kamaldev
2014-04-01
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.
Random Vortex-Street Model for a Self-Similar Plane Turbulent Jet
Victor L'vov; Anna Pomyalov; Itamar Procaccia; Rama Govindarajan
2008-03-18
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.
Vortex combustor for low NOX emissions when burning lean premixed high hydrogen content fuel
Steele, Robert C; Edmonds, Ryan G; Williams, Joseph T; Baldwin, Stephen P
2012-11-20
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.
Kerns, J.A.; Stone, R.R.; Fabyan, J.
1987-10-06
A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient magnetic field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines. 3 figs.
Kerns, John A. (Livermore, CA); Stone, Roger R. (Walnut Creek, CA); Fabyan, Joseph (Livermore, CA)
1987-01-01
A magnetically-conductive filler material bridges the gap between a multi-part magnetic shield structure which substantially encloses a predetermined volume so as to minimize the ingress or egress of magnetic fields with respect to that volume. The filler material includes a heavy concentration of single-magnetic-domain-sized particles of a magnetically conductive material (e.g. soft iron, carbon steel or the like) dispersed throughout a carrier material which is generally a non-magnetic material that is at least sometimes in a plastic or liquid state. The maximum cross-sectional particle dimension is substantially less than the nominal dimension of the gap to be filled. An epoxy base material (i.e. without any hardening additive) low volatility vacuum greases or the like may be used for the carrier material. The structure is preferably exposed to the expected ambient magnetic field while the carrier is in a plastic or liquid state so as to facilitate alignment of the single-magnetic-domain-sized particles with the expected magnetic field lines.
Nernst Effect in Magnetized Plasmas
Joglekar, Archis S; Ridgers, Christopher P; Kingham, Robert J
2015-01-01
We present nanosecond timescale Vlasov-Fokker-Planck-Maxwell modeling of magnetized plasma transport and dynamics in a hohlraum with an applied external magnetic field, under conditions similar to recent experiments. Self-consistent modeling of the kinetic electron momentum equation allows for a complete treatment of the heat flow equation and Ohm's Law, including Nernst advection of magnetic fields. In addition to showing the prevalence of non-local behavior, we demonstrate that effects such as anomalous heat flow are induced by inverse bremsstrahlung heating. We show magnetic field amplification up to a factor of 3 from Nernst compression into the hohlraum wall. The magnetic field is also expelled towards the hohlraum axis due to Nernst advection faster than frozen-in-flux would suggest. Non-locality contributes to the heat flow towards the hohlraum axis and results in an augmented Nernst advection mechanism that is included self-consistently through kinetic modeling.
VORTEX CREEP AGAINST TOROIDAL FLUX LINES, CRUSTAL ENTRAINMENT, AND PULSAR GLITCHES
Gügercino?lu, Erbil; Alpar, M. Ali E-mail: alpar@sabanciuniv.edu
2014-06-10
A region of toroidally oriented quantized flux lines must exist in the proton superconductor in the core of the neutron star. This region will be a site of vortex pinning and creep. Entrainment of the neutron superfluid with the crustal lattice leads to a requirement of superfluid moment of inertia associated with vortex creep in excess of the available crustal moment of inertia. This will bring about constraints on the equation of state. The toroidal flux region provides the moment of inertia necessary to complement the crust superfluid with postglitch relaxation behavior fitting the observations.
Vortices within vortices: hierarchical nature of vortex tubes in turbulence
Bürger, Kai; Westermann, Rüdiger; Werner, Suzanne; Lalescu, Cristian C; Szalay, Alexander; Meneveau, Charles; Eyink, Gregory L
2012-01-01
The JHU turbulence database [1] can be used with a state of the art visualisation tool [2] to generate high quality fluid dynamics videos. In this work we investigate the classical idea that smaller structures in turbulent flows, while engaged in their own internal dynamics, are advected by the larger structures. They are not advected undistorted, however. We see instead that the small scale structures are sheared and twisted by the larger scales. This illuminates the basic mechanisms of the turbulent cascade.
Synthesis and magnetic reversal of bi-conical Ni nanostructures
Biziere, N.; Lassalle Ballier, R.; Viret, M.
2011-09-15
Template synthesis in polyethylene terephthalate (PET) membranes has been used to grow hour glass shaped nickel nanowires with a constriction in the range of tens of nanometers at the center. Anisotropic magnetoresistance measurements have been performed on a single nanowire to follow magnetization reversal of the structure. The results are explained via 3D micromagnetic simulations showing the appearance of a complex vortex state close to the constriction whose propagation depends on the angle between the cone axis and the applied field. The interest of this original growth process for spintronics is discussed.
Kerns, J.A.; Stone, R.R.; Fabyan, J.
1985-02-12
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.
Previous session | Next session Session IR1 -Inverse Turbulent Cascade, Vortex Dynamics and
Marcus, Philip S.
--known. The formation of vortices, their interactions and persistence along with their tendencies to both filament and merge are the subject of many fluid experiments and numerical simulations and have analogies in plasma--containing modes in a turbulent flow span a range of scales, and in the rare cases that there are coherent features
Hawblitzel, Daniel Patrick
2006-08-16
2.13 11 June 600 hPa observations from the NOAA Wind Profiler Network............................................................................................. 37 2.14 WSR88D reflectivity from 1500 UTC 11 June to 0600 UTC 12 June...), height (blue, in meters) and wind (one full barb denotes 10 knots)............................................... 55 2.29 600 hPa BAMEX dropsonde observations of temperature (red, in degrees Celsius), dewpoint (green), height (blue...
Vortex dynamics : a window into the properties of type-II superconductors
Taylor, Benjamin Jeremy
2006-01-01
A. Superconductivity . . . . . . . . . .theory of superconductivity B. Type I . . . . . . . . . . .11] P. G. DeGennes, Superconductivity of Metals and Alloys,
POINT VORTEX DYNAMICS FOR COUPLED SURFACE/INTERIOR QG AND PROPAGATING HETON
Lim, Chjan C.
and analyzed twolayer heton models for studying the spreading phase of penetrative open ocean convection. Deep FOR OCEAN CONVECTION by Chjan C. Lim Andrew J. Majda Mathematical Sciences Dept. Courant Inst. Mathematical for open ocean convection as a response to spatially localized intense surface cool ing. In such heton
Vortex and structural dynamics of a flexible cylinder in cross-flow
Office of Scientific and Technical Information (OSTI)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.Theory of rare Kaonfor Direct Measurement(JournalFrameworkSciTech Connect(Journal
Matsui, Hiroshi (Glen Rock, NJ); Matsunaga, Tadashi (Tokyo, JP)
2010-11-16
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.
Importance of magnetic helicity in dynamos
A. Brandenburg
2004-12-15
Magnetic helicity is nearly conserved and its evolution equation provides a dynamical feedback on the alpha effect that is distinct from the conventional algebraic alpha quenching. The seriousness of this dynamical alpha quenching is particularly evident in the case of closed or periodic boxes. The explicit connection with catastrophic alpha quenching is reviewed and the alleviating effects of magnetic and current helicity fluxes are discussed.
Magnetic structure of $K$ and $?$ mesons
E. V. Luschevskaya; O. E. Solovjeva; O. V. Teryaev
2015-11-30
We explore the energy dependence of $K$ and $\\pi$ mesons off the background constant abelian magnetic field in SU(3) lattice gauge theory without dynamical quarks. The energy of neutral pseudoscalar mesons diminishes with the field, while the energy of charged one increases according with the theoretical expectation. We estimate the magnetic polarizabilities of pseudoscalar $K^0$, $\\pi^0$ and $\\pi^{\\pm}$ mesons for various quark masses. The contribution of the magnetic hyperpolarizability to kaon and pion energies was found also.
Quantum Dynamics of Topological Singularities Feynman's Influence Functional Approach
Ao, P
1998-01-01
Starting from the microscopic theory of Bardeen-Cooper-Schrieffer (BCS) for the fermionic superfluids, we show that the vortex dynamics can be followed naturally by extending Feynman's influence functional approach to incorporate the transverse force. There is a striking mutual independence of the transverse and longitudinal influences: The former has the topological origin and is insensitive to details, while the latter corresponds to the well-known damping kernel depending on details.
Magnetic levitation on a type-I superconductor as a practical demonstration experiment for students
Osorio, M R; Suderow, H
2012-01-01
We describe and discuss an experimental set-up which allows undergraduate and graduate students to view and study magnetic levitation on a type-I superconductor. The demonstration can be repeated many times using one readily available 25 liter liquid helium dewar. We study the equilibrium position of a magnet that levitates over a lead bowl immersed in a liquid hand-held helium cryostat. We combine the measurement of the position of the magnet with simple analytical calculations. This provides a vivid visualization of magnetic levitation from the balance between pure flux expulsion and gravitation. The experiment contrasts and illustrates the case of magnetic levitation with high temperature type-II superconductors using liquid nitrogen, where levitation results from partial flux expulsion and vortex physics.
Detection of vortex tubes in solar granulation from observations with Sunrise
Steiner, O; Gonzalez, N Bello; Nutto, Ch; Rezaei, R; Pillet, V Martinez; Navarro, J A Bonet; Iniesta, J C del Toro; Domingo, V; Solanki, S K; Knolker, M; Schmidt, W; Barthol, P; Gandorfer, A
2010-01-01
We have investigated a time series of continuum intensity maps and corresponding Dopplergrams of granulation in a very quiet solar region at the disk center, recorded with the Imaging Magnetograph eXperiment (IMaX) on board the balloon-borne solar observatory Sunrise. We find that granules frequently show substructure in the form of lanes composed of a leading bright rim and a trailing dark edge, which move together from the boundary of a granule into the granule itself. We find strikingly similar events in synthesized intensity maps from an ab initio numerical simulation of solar surface convection. From cross sections through the computational domain of the simulation, we conclude that these `granular lanes' are the visible signature of (horizontally oriented) vortex tubes. The characteristic optical appearance of vortex tubes at the solar surface is explained. We propose that the observed vortex tubes may represent only the large-scale end of a hierarchy of vortex tubes existing near the solar surface.
The tangential velocity profile and momentum transfer within a microgravity, vortex separator
Ellis, Michael Clay
2009-05-15
&M University (TAMU) have developed a microgravity vortex separator (MVS) capable of handling both a wide range of inlet conditions and changes in these conditions. To optimize the MVS design, the effects of nozzle area, separator geometry, and inlet flow rate...
RESEARCH ARTICLE Drag and lift reduction of a 3D bluff-body using active vortex
Wesfreid, José Eduardo
apparatus (chemical industry, energy production). From the academic point of view, it is an exciting-up with motorized vortex generators is proposed. Thanks to this active device. The optimal configurations depending academic and industrial research. From the indus- trial point of view, flow control is a way to increase
Model of coarsening and vortex formation in vibrated granular rods Igor S. Aranson
Tsimring, Lev S.
Model of coarsening and vortex formation in vibrated granular rods Igor S. Aranson Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 Lev S. Tsimring Institute for Nonlinear Science spontaneous formation of the long-range orientational order and large- scale vortices in a system of vibrated
2094 OPTICS LETTERS / Vol. 28, No. 21 / November 1, 2003 Fundamental and vortex solitons in a
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
"Development of a Free Vortex Wake Method Code for Offshore Floating Wind Turbines"
Mountziaris, T. J.
"Development of a Free Vortex Wake Method Code for Offshore Floating Wind Turbines" Andrew Sciotti Professor Matthew Lackner Shujian Liu Offshore floating wind turbines (OFWTs) require a unique aerodynamic in refining current mathematical models of offshore wind turbines while also allowing efficient simulations
Sediment resuspension and erosion by vortex rings R. J. Munro,1,a
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
Hierarchical Colloidal Vortex Rings in a Constant Electric Field Yilong Han and David G. Grier
Grier, David
in the bulk of chargestabilized colloidal suspensions when electrohydrodynamic forces due to constant appliedHierarchical Colloidal Vortex Rings in a Constant Electric Field Yilong Han and David G. Grier used [1, 2] to study interfacial col loidal electrokinetic phenomena. An aqueous suspension
Hierarchical Colloidal Vortex Rings in a Constant Electric Field Yilong Han and David G. Grier
Grier, David
in the bulk of charge-stabilized colloidal suspensions when electrohydrodynamic forces due to constant appliedHierarchical Colloidal Vortex Rings in a Constant Electric Field Yilong Han and David G. Grier used [1, 2] to study interfacial col- loidal electrokinetic phenomena. An aqueous suspension
Self-consistent anisotropic oscillator with cranked angular and vortex velocities
G. Rosensteel
1992-11-05
The Kelvin circulation is the kinematical Hermitian observable that measures the true character of nuclear rotation. For the anisotropic oscillator, mean field solutions with fixed angular momentum and Kelvin circulation are derived in analytic form. The cranking Lagrange multipliers corresponding to the two constraints are the angular and vortex velocities. Self-consistent solutions are reported with a constraint to constant volume.
Under consideration for publication in J. Fluid Mech. 1 Drop impact into a deep pool: vortex
Deegan, Robert
Under consideration for publication in J. Fluid Mech. 1 Drop impact into a deep pool: vortex of Michigan, Ann Arbor, Michigan 48109, USA 2 Division of Physical Sciences and Engineering & Clean Combustion Arabia 3 Physics of Fluids Group, Faculty of Science and Technology, Mesa+ Institute, University
Instabilities due a vortex at a density interface: gravitational and centrifugal effects
Dixit, Harish
Instabilities due a vortex at a density interface: gravitational and centrifugal effects Harish N showed recently that the flow is subject to centrifugal Rayleigh-Taylor and spiral Kelvin for example [5]). In the absence of gravity, centrifugal forces are predominant, and we showed recently [4
Superconducting and magnetic properties of Sr?Ir?Sn??
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)
2014-10-01
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)/k_{B}T_{c} = 2.1(1) indicates that Sr?Ir?Sn?? should be considered as a strong-coupling superconductor.
Superconducting and magnetic properties of Sr?Ir?Sn??
Biswas, P. K.; Wang, Kefeng; Amato, A.; Khasanov, R.; Luetkens, H.; Petrovic, C.; Cook, R. M.; Lees, M. R.; Morenzoni, E.
2014-10-10
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)/k_{B}T_{c} = 2.1(1) indicates that Sr?Ir?Sn?? should be considered as a strong-coupling superconductor.
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.
2014-10-10
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
Friedland, Lazar
2015-01-01
magnetic data storing to waste water decontamination [2] and medical diagnostics and treatments [35]. In particular, the ability to precisely control the magnetization dynamics constitutes a major advantage is obviously undesirable for a reliable control of the magnetization dynam- ics. Increasing the magnetic
Periodic magnetic structures generated by spin–polarized currents in nanostripes
Volkov, Oleksii M. Sheka, Denis D.; Kravchuk, Volodymyr P.; Gaididei, Yuri; Mertens, Franz G.
2013-11-25
The influence of a transverse spin–polarized current on long ferromagnetic nanostripes is studied numerically. The magnetization behavior is analyzed for all range of the applied currents, up to the saturation. It is shown that the saturation current is a nonmonotonic function of the stripe width. A number of stable periodic magnetization structures are observed below the saturation. Type of the periodical structure depends on the stripe width. Besides the one–dimensional domain structure, typical for narrow wires, and the two–dimensional vortex–antivortex lattice, typical for wide films, a number of intermediate structures are observed, e.g., cross–tie and diamond state.
Fryberger, D.
1984-12-01
In this talk on magnetic monopoles, first the author briefly reviews some historical background; then, the author describes what several different types of monopoles might look like; and finally the author discusses the experimental situation. 81 references.
Enhancement of artificial magnetism via resonant bianisotropy
Markovich, Dmitry; Shalin, Alexander; Samusev, Anton; Krasnok, Alexander; Belov, Pavel; Ginzburg, Pavel
2015-01-01
All-dielectric "magnetic light" nanophotonics based on high refractive index nanoparticles allows controlling magnetic component of light at nanoscale without having high dissipative losses. The artificial magnetic optical response of such nanoparticles originates from circular displacement currents excited inside those structures and strongly depends on geometry and dispersion of optical materials. Here a new approach for increasing magnetic response via resonant bianisotropy effect is proposed and analyzed. The key mechanism of enhancement is based on electric-magnetic interaction between two electrically and magnetically resonant nanoparticles of all-dielectric dimer nanoantenna. It was shown that proper geometrical arrangement of the dimer in respect to the incident illumination direction allows flexible control over all vectorial components of magnetic polarizability, tailoring the later in the dynamical range of 100 % and enhancement up to 36 % relative to performances of standalone spherical particles....
Model Characterization of Magnetic Microrobot Navigating in Viscous Environment
Paris-Sud XI, Université de
. Indeed most untethered microrobot propulsion schemes based on magnetic pulling have to face importantModel Characterization of Magnetic Microrobot Navigating in Viscous Environment Karim Belharet1.folio@ensi-bourges.fr,antoine.ferreira@ensi-bourges.fr Abstract. In this paper we aim to characterize and validate the system's dynamic model of a magnetic
Motion of charged particles in ABC magnetic fields Alejandro Luque #
Motion of charged particles in ABC magnetic fields Alejandro Luque # Departament de Matemâ?? atica consequences of our study are the existence of confinement regions of charges near some magnetic lines, magnetic field, Hamiltonian dynamical system, elÂ liptic equilibrium point, quasiÂperiodic solution
Fitzpatrick, Richard
inside the plasma. Such island chains degrade plasma confinement be- cause both heat and particlesImproved evolution equations for magnetic island chains in toroidal pinch plasmas subject nonlinear dynamics of magnetic islands due to resonant magnetic perturbations Phys. Plasmas 21, 122502 (2014
Loss, Daniel
soliton/vortex ring by density engineering of a BoseEinstein condensate I. Shomroni, E. Lahoud, S. Levy and J. Steinhauer* When two BoseEinstein condensates collide with high collisional energy
Donnelly, Jessica Mary
2004-01-01
This paper describes a scatter diagram approach for the classification of large numbers of current profiles for use in the prediction of riser fatigue damage due to vortex-induced vibration. Scatter diagrams have long been ...
arXiv:1206.2498v2[cond-mat.other]19Nov2012 Quantum vortex reconnections
Caliari, Marco
(Dated: 21 November 2012) We study reconnections of quantum vortices by numerically solving the governing . They are the key to understanding quantum turbulence8 , a disordered state of vortex lines which is easily created
Van Gorder, Robert A.
2014-06-15
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.
Royet, J.M.
2011-01-01
J. Royet, "Magnet Cable Manufacturing", oral presentation atDivision Magnet Cable Manufacturing J. Royet October 1990J I Magnet Cable Manufacturing* John Royet Accelerator &
Jansen, Jacobus F.A.; Schoeder, Heiko; Lee, Nancy Y.; Stambuk, Hilda E.; Wang Ya; Fury, Matthew G.; Patel, Senehal G.; Pfister, David G.; Shah, Jatin P.; Koutcher, Jason A.; Shukla-Dave, Amita
2012-01-01
Purpose: To correlate proton magnetic resonance spectroscopy ({sup 1}H-MRS), dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), and {sup 18}F-labeled fluorodeoxyglucose positron emission tomography ([{sup 18}F]FDG PET) of nodal metastases in patients with head and neck squamous cell carcinoma (HNSCC) for assessment of tumor biology. Additionally, pretreatment multimodality imaging was evaluated for its efficacy in predicting short-term response to treatment. Methods and Materials: Metastatic neck nodes were imaged with {sup 1}H-MRS, DCE-MRI, and [{sup 18}F]FDG PET in 16 patients with newly diagnosed HNSCC, before treatment. Short-term patient radiological response was evaluated at 3 to 4 months. Correlations among {sup 1}H-MRS (choline concentration relative to water [Cho/W]), DCE-MRI (volume transfer constant [K{sup trans}]; volume fraction of the extravascular extracellular space [v{sub e}]; and redistribution rate constant [k{sub ep}]), and [{sup 18}F]FDG PET (standard uptake value [SUV] and total lesion glycolysis [TLG]) were calculated using nonparametric Spearman rank correlation. To predict short-term responses, logistic regression analysis was performed. Results: A significant positive correlation was found between Cho/W and TLG ({rho} = 0.599; p = 0.031). Cho/W correlated negatively with heterogeneity measures of standard deviation std(v{sub e}) ({rho} = -0.691; p = 0.004) and std(k{sub ep}) ({rho} = -0.704; p = 0.003). Maximum SUV (SUVmax) values correlated strongly with MRI tumor volume ({rho} = 0.643; p = 0.007). Logistic regression indicated that std(K{sup trans}) and SUVmean were significant predictors of short-term response (p < 0.07). Conclusion: Pretreatment multimodality imaging using {sup 1}H-MRS, DCE-MRI, and [{sup 18}F]FDG PET is feasible in HNSCC patients with nodal metastases. Additionally, combined DCE-MRI and [{sup 18}F]FDG PET parameters were predictive of short-term response to treatment.
Mechanics of Individual, Isolated Vortices in a Cuprate Superconductor
Ophir M. Auslaender; Lan Luan; Eric W. J. Straver; Jennifer E. Hoffman; Nicholas C. Koshnick; Eli Zeldov; Douglas A. Bonn; Ruixing Liang; Walter N. Hardy; Kathryn A. Moler
2008-09-16
Superconductors often contain quantized microscopic whirlpools of electrons, called vortices, that can be modeled as one-dimensional elastic objects. Vortices are a diverse playground for condensed matter because of the interplay between thermal fluctuations, vortex-vortex interactions, and the interaction of the vortex core with the three-dimensional disorder landscape. While vortex matter has been studied extensively, the static and dynamic properties of an individual vortex have not. Here we employ magnetic force microscopy (MFM) to image and manipulate individual vortices in detwinned, single crystal YBa2Cu3O6.991 (YBCO), directly measuring the interaction of a moving vortex with the local disorder potential. We find an unexpected and dramatic enhancement of the response of a vortex to pulling when we wiggle it transversely. In addition, we find enhanced vortex pinning anisotropy that suggests clustering of oxygen vacancies in our sample and demonstrates the power of MFM to probe vortex structure and microscopic defects that cause pinning.
Vortex Formation and Evolution in Planet Harboring Disks under Thermal Relaxation
Gomes, A Lobo; Uribe, A L; Pinilla, P; Surville, C
2015-01-01
We study the evolution of planet-induced vortices in radially stratified disks, with initial conditions allowing for radial buoyancy. For this purpose we run global two dimensional hydrodynamical simulations, using the PLUTO code. Planet-induced vortices are a product of the Rossby wave instability (RWI) triggered in the edges of a planetary gap. In this work we assess the influence of radial buoyancy for the development of the vortices. We found that radial buoyancy leads to smoother planetary gaps, which generates weaker vortices. This effect is less pronounced for locally isothermal and quasi-isothermal (very small cooling rate) disks. We observed the formation of two generations of vortices. The first generation of vortices is formed in the outer wall of the planetary gap. The merged primary vortex induces accretion, depleting the mass on its orbit. This process creates a surface density enhancement beyond the primary vortex position. The second generation of vortices arise in this surface density enhance...
Geometrically induced magnetic catalysis and critical dimensions
Antonino Flachi; Kenji Fukushima; Vincenzo Vitagliano
2015-04-27
We discuss the combined effect of magnetic fields and geometry in interacting fermionic systems. At leading order in the heat-kernel expansion, the infrared singularity (that in flat space leads to the magnetic catalysis) is regulated by the chiral gap effect, and the catalysis is deactivated by the effect of the scalar curvature. We discover that an infrared singularity is found in higher-order terms that mix the magnetic field with curvature, and these lead to a novel form of geometrically induced magnetic catalysis. The dynamical mass squared is then modified not only due to the chiral gap effect by an amount proportional to the curvature, but also by a magnetic shift $\\propto (4-D)eB$, where $D$ represents the number of space-time dimensions. We argue that $D=4$ is a critical dimension across which the behavior of the magnetic shift changes qualitatively.
Thomas Wiegelmann; Bernd Inhester
2006-12-21
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.
Hietala, Niklas Hänninen, Risto
2014-11-15
Van Gorder considers a formulation of the local induction approximation, which allows the vortex to move in the direction of the reference axis [“General rotating quantum vortex filaments in the low-temperature Svistunov model of the local induction approximation,” Phys. Fluids 26, 065105 (2014)]. However, in his analytical and numerical study he does not use it. A mistake in the torsion of a helical vortex is also corrected.
Voltage-Controlled Magnetic Dynamics in Nanoscale Magnetic Tunnel Junctions
Alzate Vinasco, Juan Guillermo
2014-01-01
SWITHCHED VIA THERMAL ACTIVATION OR PRECESSIONAL is partially lowered, thermal activation can result in astate can fall via thermal activation. Note that the large
Voltage-Controlled Magnetic Dynamics in Nanoscale Magnetic Tunnel Junctions
Alzate Vinasco, Juan Guillermo
2014-01-01
and D. M. Treger, "Spintronics: A Spin-Based ElectronicsS. S. P. Parkin, "Spintronics," Annual Review of CondensedJ. Fabian, and S. Das Sarma, "Spintronics: Fundamentals and
Neutron scattering and thermodynamic studies of quantum magnetism on the kagomé lattice
Chisnell, Robin Michael Daub
2014-01-01
The geometry of the kagome lattice leads to exciting novel magnetic behavior in both ferromagnetic and antiferromagnetic systems. The collective spin dynamics were investigated in a variety of magnetic materials featuring ...
Magnetization Oscillation of a Spinor Condensate Induced by Magnetic Field Gradient
Jie Zhang; Baoguo Yang; Yunbo Zhang
2011-05-02
We study the spin mixing dynamics of ultracold spin-1 atoms in a weak non-uniform magnetic field with field gradient $G$, which can flip the spin from +1 to -1 so that the magnetization $m=\\rho_{+}-\\rho_{-}$ is not any more a constant. The dynamics of $m_F=0$ Zeeman component $\\rho_{0}$, as well as the system magnetization $m$, are illustrated for both ferromagnetic and polar interaction cases in the mean-field theory. We find that the dynamics of system magnetization can be tuned between the Josephson-like oscillation similar to the case of double well, and the interesting self-trapping regimes, i.e. the spin mixing dynamics sustains a spontaneous magnetization. Meanwhile the dynamics of $\\rho_0$ may be sufficiently suppressed for initially imbalanced number distribution in the case of polar interaction. A "beat-frequency" oscillation of the magnetization emerges in the case of balanced initial distribution for polar interaction, which vanishes for ferromagnetic interaction.
Malfait, Nicole
1999-01-01
. TheconservationlawsforlinearandangularmomentainaSchr¨odingerChernSimons field theory modelling vortex dynamics in planar superconductors flux vortices in thin-film superconductors [9]. The Lagrangian is of first-order Schr in superconductors at very low temperature [1, 14]. For time-independent fields, the Lagrangian reduces
Patterned Magnetic Nanostructures and Quantized Magnetic Disks
-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
Zakharov, Leonid E.
plasma facing lithium streams driven by magnetic propulsion, b)' 1 mm thick patchy separation guide wall
Dynamics of a confined dusty fluid in a sheared ion flow
Laishram, Modhuchandra; Sharma, Devendra; Kaw, Predhiman K. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)
2014-07-15
Dynamics of an isothermally driven dust fluid is analyzed which is confined in an azimuthally symmetric cylindrical setup by an effective potential and is in equilibrium with an unconfined sheared flow of a streaming plasma. Cases are analyzed where the confining potential constitutes a barrier for the driven fluid, limiting its spatial extension and boundary velocity. The boundary effects entering the formulation are characterized by applying the appropriate boundary conditions and a range of solutions exhibiting single and multiple vortex are obtained. The equilibrium solutions considered in the cylindrical setup feature a transition from single to multiple vortex state of the driven flow. Effects of (i) the variation in dust viscosity, (ii) coupling between the driving and the driven fluid, and (iii) a friction determining the equilibrium dynamics of the driven system are characterized.
Two-step liquid-solid vortex transition with the field along the ab planes in YBa2Cu3O7 crystals
Grigera, Santiago
, in the mixed state of clean and twinned YBa2Cu3O7 single crystals, support the existence of a vortex and Instituto Balseiro, Comisio´n Nacional de Energi´a Ato´mica, 8400 San Carlos de Bariloche, Argentina-smectic phase when the vortices interact with an attractive periodic potential. The transition from the vortex
Nonequilibrium Spin Magnetization Quantum Transport Equations
Buot, F A; Otadoy, R E S; Villarin, D L
2011-01-01
The classical Bloch equations of spin magnetization transport is extended to fully time-dependent and highly-nonlinear nonequilibrium quantum distribution function (QDF) transport equations. The leading terms consist of the Boltzmann kinetic equation with spin-orbit coupling in a magnetic field together with spin-dependent scattering terms which do not have any classical analogue, but should incorporate the spatio-temporal-dependent phase-space dynamics of Elliot-Yafet and D'yakonov-Perel scatterings. The resulting magnetization QDF transport equation serves as a foundation for computational spintronic and nanomagnetic device applications, in performing simulation of ultrafast-switching-speed/low-power performance and reliability analyses.
Kapitza problem for the magnetic moments of synthetic antiferromagnetic systems
Dzhezherya, Yu. I.; Demishev, K. O.; Korenivskii, V. N.
2012-08-15
The dynamics of magnetization in synthetic antiferromagnetic systems with the magnetic dipole coupling in a rapidly oscillating field has been examined. It has been revealed that the system can behave similar to the Kapitza pendulum. It has been shown that an alternating magnetic field can be efficiently used to control the magnetic state of a cell of a synthetic antiferromagnet. Analytical relations have been obtained between the parameters of such an antiferromagnet and an external magnetic field at which certain quasistationary states are implemented.
Boriskina, Svetlana V; 10.1039/C1NR11406A
2011-01-01
Efficient delivery of light into nanoscale volumes by converting free photons into localized charge-density oscillations (surface plasmons) enables technological innovation in various fields from biosensing to photovoltaics and quantum computing. Conventional plasmonic nanostructures are designed as nanoscale analogs of radioantennas and waveguides. Here, we discuss an alternative approach for plasmonic nanocircuit engineering that is based on molding the optical powerflow through 'vortex nanogears' around a landscape of local phase singularities 'pinned' to plasmonic nanostructures. We show that coupling of several vortex nanogears into transmission-like structures results in dramatic optical effects, which can be explained by invoking a hydrodynamic analogy of the 'photon fluid'. The new concept of vortex nanogear transmissions (VNTs) provides new design principles for the development of complex multi-functional phase-operated photonics machinery and, therefore, generates unique opportunities for light gene...
Svetlana V. Boriskina; Bjoern M. Reinhard
2011-12-07
Efficient delivery of light into nanoscale volumes by converting free photons into localized charge-density oscillations (surface plasmons) enables technological innovation in various fields from biosensing to photovoltaics and quantum computing. Conventional plasmonic nanostructures are designed as nanoscale analogs of radioantennas and waveguides. Here, we discuss an alternative approach for plasmonic nanocircuit engineering that is based on molding the optical powerflow through 'vortex nanogears' around a landscape of local phase singularities 'pinned' to plasmonic nanostructures. We show that coupling of several vortex nanogears into transmission-like structures results in dramatic optical effects, which can be explained by invoking a hydrodynamic analogy of the 'photon fluid'. The new concept of vortex nanogear transmissions (VNTs) provides new design principles for the development of complex multi-functional phase-operated photonics machinery and, therefore, generates unique opportunities for light generation, harvesting and processing on the nanoscale.
Superconducting Magnet Division
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
Ultrasound scattering and the study of vortex correlations in disordered flows
Denis Boyer; Fernando Lund
1999-12-14
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.
Extraordinary optical transmission and vortex excitation by periodic arrays of Fresnel zone plates
Roszkiewicz, A
2013-01-01
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.
Satti, John A. (Naperville, IL)
1980-01-01
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.
Investigation of Peptide Folding by Nuclear Magnetic Resonance Spectroscopy
Hwang, SoYoun
2012-07-16
. Solution-state nuclear magnetic resonance (NMR) is a powerful technique to investigate protein structure, dynamics, and folding mechanisms, since it provides residue-specific information. One of the major contributions that govern protein structure appears...
Nanostructured magnetic materials
Chan, Keith T.
2011-01-01
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
Kim, S.; Hu, Chia-Ren; Andrews, MJ.
2004-01-01
A numerical scheme to study the mixed states in a mesoscopic type-II superconducting cylinder is described. Steady-state configurations and transient behavior of the magnetic vortices for various values of the applied magnetic field H are presented...
Science Drivers and Technical Challenges for Advanced Magnetic Resonance
Mueller, Karl T.; Pruski, Marek; Washton, Nancy M.; Lipton, Andrew S.
2013-03-07
This report recaps the "Science Drivers and Technical Challenges for Advanced Magnetic Resonance" workshop, held in late 2011. This exploratory workshop's goal was to discuss and address challenges for the next generation of magnetic resonance experimentation. During the workshop, participants from throughout the world outlined the science drivers and instrumentation demands for high-field dynamic nuclear polarization (DNP) and associated magnetic resonance techniques, discussed barriers to their advancement, and deliberated the path forward for significant and impactful advances in the field.
Hay, K.J.; Qi, S.; Holden, B.; Helgeson, N.; Fraser, M.E.
1999-03-01
Chromium electroplating is an essential DOD process. Chromium has a combination of qualities that are very difficult to substitute, however, the process itself is inefficient, resulting in the production of byproduct gases that rise and create a mist of chromic acid (strongly regulated as an air pollutant) above the plating tank. Venturi/Vortex Scrubber Technology (VVST) was designed to control chromium electroplating emissions by collecting the gas bubbles before they burst at the solution`s surface. This project demonstrated the Venturi/Vortex Scrubber Technology at the Marine Corps Logistics Base (MCLB) in Albany, GA. This study concluded that the PLRS was able to reduce the flow rate of the current conventional ventilation system at the one tank chromium electroplating facility at MCLB Albany by 63 percent. If new ventilation and control equipment were to be installed at MCLB Albany, this system would offer a 25 percent reduction in capital costs and a 48 percent reduction in annual costs, representing 36 percent in life-cycle cost savings. This study also presented a strong case for the use of Spark-Induced Breakdown Spectroscopy for monitoring real-time chromium emissions above a chromium electroplating tank.
Direct femtosecond laser ablation of copper with an optical vortex beam
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)
2014-09-21
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
Plasma detachment and momentum transfer in magnetic nozzles
Choueiri, Edgar
Plasma detachment and momentum transfer in magnetic nozzles Justin M. Little and Edgar Y. Choueiri Electric Propulsion and Plasma Dynamics Laboratory, Princeton University, Princeton, NJ, 08544 The nature of momentum transfer and the resulting thrust generation in magnetic nozzles is investigated. First
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Up: APS Storage Ring Parameters Previous: Longitudinal bunch profile and Magnets and Power Supplies Dipole Magnets and Power Supplies Value Dipole Number 80+1 No. of power...
SUPERCONDUCTING MAGNETIC ENERGY STORAGE
Hassenzahl, W.
2011-01-01
Superconducting 30-MJ Energy Storage Coil", Proc. 19 80 ASC,Superconducting Magnetic Energy Storage Plant", IEEE Trans.SlIperconducting Magnetic Energy Storage Unit", in Advances
Superconducting and magnetic properties of Sr3Ir4Sn13
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Biswas, P. K.; Amato, A.; Khasanov, R.; Luetkens, H.; Wang, Kefeng; Petrovic, C.; Cook, R. M.; Lees, M. R.; Morenzoni, E.
2014-10-10
In this research, 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?? withmore »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.« less
Thermoelectric Conductivities at Finite Magnetic Field and the Nernst Effect
Kim, Keun-Young; Seo, Yunseok; Sin, Sang-Jin
2015-01-01
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.
SYNCHROTRON AGING IN FILAMENTED MAGNETIC FIELDS
Eilek, Jean
SYNCHROTRON AGING IN FILAMENTED MAGNETIC FIELDS J. A. EILEK 1;2 , D. B. MELROSE 2 and M.A. WALKER 2 radio sources whose dynamical ages are known to be significantly greater than the ages inferred from; In addition, it is becoming increasingly clear that radio galaxies suffer from an ``aging problem
Recanati, Catherine
A finite element method with mesh adaptivity for computing vortex states in fastrotating BoseEinstein Abstract Numerical computations of stationary states of fastrotating BoseEinstein condensates require rotation rates). Key words: Gross--Pitaevskii equation, finite element method, mesh adaptivity, BoseEinstein
Bergman, Keren
the efficient scalability of the architecture under uniform and random traffic conditions while maintaining high1242 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 20, NO. 8, AUGUST 2002 Performances of the Data Vortex Switch Architecture Under Nonuniform and Bursty Traffic Qimin Yang, Member, IEEE, and Keren Bergman
. This observation confirms the role of discrete surface modes in vortex formation. However, when we used a tightly. The nucleation process has been a subject of much theoretical interest [1]. Experiments with Bose. These resonances were close to the frequencies of excitation for surface modes of different multipolarity
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
Weissmann, Steffen
To appear in the ACM SIGGRAPH conference proceedings Filament-based smoke with vortex shedding filaments is highly attractive for the creation of special effects because it gives artists full control filaments over time. Because filaments offer a very compact description of fluid flow, real time
arXiv:nlin.SI/0612065v129Dec2006 FINITE-GAP SOLUTIONS OF THE VORTEX FILAMENT EQUATION
Calini, Annalisa
arXiv:nlin.SI/0612065v129Dec2006 FINITE-GAP SOLUTIONS OF THE VORTEX FILAMENT EQUATION: ISOPERIODIC filament equation in a neighborhood of multiply covered circles. We construct these solutions by means that matches the deformation data with the knot type of the resulting filament. 1. Introduction In this sequel
Steinbock, Oliver
Stationary Vortex Loops Induced by Filament Interaction and Local Pinning in a Chemical Reaction rings are three-dimensional excitation waves rotating around one-dimensional filament loops but curved filaments. The absence of filament motion can be explained by repulsive interaction
Manuel, Lance
of a deepwater drilling riser. We examine such data from the monitoring of riser accelerations and vortex a deepwater drilling riser. The site has a water depth of 1,000 meters. These riser acceleration data consist of a Drilling Riser using Empirical and Spectral Procedures Tanapat Srivilairit and Lance Manuel Department
Radiative Magnetic Reconnection in Astrophysics
Uzdensky, Dmitri A
2015-01-01
I review a new rapidly growing area of high-energy plasma astrophysics --- radiative magnetic reconnection, i.e., a reconnection regime where radiation reaction influences reconnection dynamics, energetics, and nonthermal particle acceleration. This influence be may be manifested via a number of astrophysically important radiative effects, such as radiation-reaction limits on particle acceleration, radiative cooling, radiative resistivity, braking of reconnection outflows by radiation drag, radiation pressure, viscosity, and even pair creation at highest energy densities. Self-consistent inclusion of these effects in magnetic reconnection theory and modeling calls for serious modifications to our overall theoretical approach to the problem. In addition, prompt reconnection-powered radiation often represents our only observational diagnostic tool for studying remote astrophysical systems; this underscores the importance of developing predictive modeling capabilities to connect the underlying physical condition...
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Zhu, S.; Cai, Y.; Rote, D.M.; Chen, S.S.
1998-01-01
Magnetic damping is one of the important parameters that control the response and stability of maglev systems. An experimental study to measure magnetic damping directly is presented. A plate attached to a permanent magnet levitated on a rotating drum was tested to investigate the effect of various parameters, such as conductivity, gap, excitation frequency, and oscillation amplitude, on magnetic damping. The experimental technique is capable of measuring all of the magnetic damping coefficients, some of which cannot be measured indirectly.
Murat Altay, H.; Speth, Raymond L.; Hudgins, Duane E.; Ghoniem, Ahmed F.
2009-11-15
The combustion dynamics of propane-air flames are investigated in an atmospheric pressure, atmospheric inlet temperature, lean, premixed backward-facing step combustor. We modify the location of the fuel injector to examine the impact of equivalence ratio oscillations arriving at the flame on the combustion dynamics. Simultaneous pressure, velocity, heat-release rate and equivalence ratio measurements and high-speed video from the experiments are used to identify and characterize several distinct operating modes. When the fuel is injected far upstream from the step, the equivalence ratio arriving at the flame is steady and the combustion dynamics are controlled only by flame-vortex interactions. In this case, different dynamic regimes are observed depending on the operating parameters. When the fuel is injected close to the step, the equivalence ratio arriving at the flame exhibits oscillations. In the presence of equivalence ratio oscillations, the measured sound pressure level is significant across the entire range of lean mean equivalence ratios even if the equivalence ratio oscillations arriving at the flame are out-of-phase with the pressure oscillations. The combustion dynamics are governed primarily by the flame-vortex interactions, while the equivalence ratio oscillations have secondary effects. The equivalence ratio oscillations could generate variations in the combustion dynamics in each cycle under some operating conditions, destabilize the flame at the entire range of the lean equivalence ratios, and increase the value of the mean equivalence ratio at the lean blowout limit. (author)
Najmabadi, Farrokh
in the boundary of the jet. Even though the magnetic pressure PB B2 /8 exceeded both the plasma ram pressure Pr nm evolution, astrophysical jets, etc. 1,2 . In the field of inertial fusion, confinement of an expanding of the plasma jet in the plane perpendicular to the B field as due to curvature of the polarization fields
Hay, K.J.; Qi, S.; Northrup, J.I.; Heck, S.R.
1998-07-01
Chromium has a combination of qualities that give chromium electroplating an important role in coating military hardware and armament. However, chromium electroplating and chromium anodizing operations create hazardous air pollutants in the form of hexavalent chromium. Conventional technologies for controlling this pollutant are expensive, noisy, and use a lot of energy and water. Consequently, an air pollution problem is turned into a water pollution problem that also requires treatment. There is a need for an economical control option that pollutes less than conventional technologies. This project developed control technologies to effectively and economically control hazardous air emissions from Army chromium electroplating and anodizing operations, primarily focusing on the development of the Venturi/Vortex Scrubber technology (VVST).
Non-Diffracting Electron Vortex Beams Balancing Their Electron-Electron Interactions
Maor Mutzafi; Ido Kaminer; Gal Harari; Mordechai Segev
2015-10-10
By introducing concepts of beam shaping into quantum mechanics, we show how interference effects of the quantum wavefunction describing multiple electrons can exactly balance the repulsion among the electrons. With proper shaping of the fermionic wavefunction, we propose non-diffracting quantum wavepackets of multiple electrons that can also carry orbital angular momentum, in the form of multi-electron non-diffracting vortex beams. The wavefunction is designed to compensate for both the repulsion between electrons and for the diffraction-broadening. This wavefunction shaping facilitates the use of electron beams of higher current in numerous applications, thereby improving the signal-to-noise-ratio in electron microscopy and related systems without compromising on the spatial resolution. Our scheme potentially applies for any beams of charged particles, such as protons, muons and ion beams.
Ruane, Garreth J; Huby, Elsa; Mawet, Dimitri; Delacroix, Christian; Carlomagno, Brunella; Piron, Pierre; Swartzlander, Grover A
2015-01-01
We present methods for optimizing pupil and focal plane optical elements that improve the performance of vortex coronagraphs on telescopes with obstructed or segmented apertures. Phase-only and complex masks are designed for the entrance pupil, focal plane, and the plane of the Lyot stop. Optimal masks are obtained using both analytical and numerical methods. The latter makes use of an iterative error reduction algorithm to calculate "correcting" optics that mitigate unwanted diffraction from aperture obstructions. We analyze the achieved performance in terms of starlight suppression, contrast, off-axis image quality, and chromatic dependence. Manufacturing considerations and sensitivity to aberrations are also discussed. This work provides a path to joint optimization of multiple coronagraph planes to maximize sensitivity to exoplanets and other faint companions.