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


1

The strength of galactic magnetic fields  

Science Journals Connector (OSTI)

... UK THE magnitudes of galactic magnetic fields are usually estimated from measurements of the radio synchroton emission arising from acceleration of cosmic-ray electrons in the magnetic field. To interpret ...

X. Chi; A. W. Wolfendale

1993-04-15T23:59:59.000Z

2

Relationship between the shape of equilibrium magnetic surfaces and the magnetic field strength  

SciTech Connect (OSTI)

A local analysis of the magnetic field near an equilibrium magnetic surface shows that there is generally no relationship between the magnetic field strength and the shape of the surface. However, the relationship exists under additional requirements such as the absence of the toroidal current, symmetry conservation, and the conservation of the magnetic field strength distribution on the nearest surface. An equilibrium magnetic surface can be calculated by specifying three functions of two angular variables-the magnetic field strength, the periodic component of the magnetic potential, and the mean curvature of the surface.

Skovoroda, A. A. [Russian Research Centre Kurchatov Institute, Nuclear Fusion Institute (Russian Federation)

2007-07-15T23:59:59.000Z

3

Estimation of the Residual Magnetic Field Strength Inside a Pipeline after Testing by a Magnetic Flaw Detector  

Science Journals Connector (OSTI)

The residual magnetic field strength inside a pipeline after testing by a magnetic flaw detector ... demagnetizing local joint-pipe sections in carrying out repair-welding works is proposed.

R. V. Zagidulin; V. F. Muzhitskii

2003-07-01T23:59:59.000Z

4

Effect of low transverse magnetic field on the confinement strength in a quasi-1D wire  

SciTech Connect (OSTI)

Transport measurements in a quasi-one dimensional (1D) quantum wire are reported in the presence of low transverse magnetic field. Differential conductance shows weak quantised plateaus when the 2D electrons are squeezed electrostatically. Application of a small transverse magnetic field (0.2T) enhances the overall degree of quantisation due to the formation of magneto-electric subbands. The results show the role of magnetic field to fine tune the confinement strength in low density wires when interaction gives rise to double row formation.

Kumar, Sanjeev [London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH (United Kingdom); Thomas, K. J. [London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK and Department of Electronic and Electrical Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Smith, L. W.; Farrer, I.; Ritchie, D. A.; Jones, G. A. C.; Griffiths, J. [Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 OHE (United Kingdom); Pepper, M. [London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK and Department of Electrical and Electronic Engineering, Torrington Place, London WC1E 7JE (United Kingdom)

2013-12-04T23:59:59.000Z

5

X-Ray–Line Diagnostic of Magnetic Field Strength for High-Temperature Plasmas  

Science Journals Connector (OSTI)

An x-ray line diagnostic for use in magnetic field measurements in high-temperature plasmas has been identified. The intensity of the otherwise strictly forbidden 1s22s22p1/22p3/243s1/2??P03?1s22s22p6??S01 transition in neonlike ions is shown to depend on the magnetic field strength. The field dependence is illustrated between one and 3 T in the Ar8+ spectrum. The line is well resolved, bright, and close to reference lines, making it an experimentally simple to use diagnostic.

P. Beiersdorfer; J. H. Scofield; A. L. Osterheld

2003-06-13T23:59:59.000Z

6

Magnetic Field Strengths Derived from Various Lines in the Umbral Spectrum  

Science Journals Connector (OSTI)

Profiles of various lines in the spectra of umbrae are discussed, emphasizing the use of purely umbral lines. In the dark core of a large umbra the field strengths measured from various lines are the same, yie...

C. Zwaan; J. Buurman

1971-01-01T23:59:59.000Z

7

Permanent magnet multipole with adjustable strength  

DOE Patents [OSTI]

Two or more magnetically soft pole pieces are symmetrically positioned along a longitudinal axis to provide a magnetic field within a space defined by the pole pieces. Two or more permanent magnets are mounted to an external magnetically-soft cylindrical sleeve which rotates to bring the permanent magnets into closer coupling with the pole pieces and thereby adjustably control the field strength of the magnetic field produced in the space defined by the pole pieces. The permanent magnets are preferably formed of rare earth cobalt (REC) material which has a high remanent magnetic field and a strong coercive force. The pole pieces and the permanent magnets have corresponding cylindrical surfaces which are positionable with respect to each other to vary the coupling therebetween. Auxiliary permanent magnets are provided between the pole pieces to provide additional magnetic flux to the magnetic field without saturating the pole pieces.

Halbach, Klaus (Berkeley, CA)

1985-01-01T23:59:59.000Z

8

Permanent-magnet multipole with adjustable strength  

DOE Patents [OSTI]

Two or more magnetically soft pole pieces are symmetrically positioned along a longitudinal axis to provide a magnetic field within a space defined by the pole pieces. Two or more permanent magnets are mounted to an external magnetically-soft cylindrical sleeve which rotates to bring the permanent magnets into closer coupling with the pole pieces and thereby adjustably control the field strength of the magnetic field produced in the space defined by the pole pieces. The permanent magnets are preferably formed of rare earth cobalt (REC) material which has a high remanent magnetic field and a strong coercive force. The pole pieces and the permanent magnets have corresponding cylindrical surfaces which are positionable with respect to each other to vary the coupling there between. Auxiliary permanent magnets are provided between the pole pieces to provide additional magnetic flux to the magnetic field without saturating the pole pieces.

Halbach, K.

1982-09-20T23:59:59.000Z

9

THE STRENGTH AND RADIAL PROFILE OF THE CORONAL MAGNETIC FIELD FROM THE STANDOFF DISTANCE OF A CORONAL MASS EJECTION-DRIVEN SHOCK  

SciTech Connect (OSTI)

We determine the coronal magnetic field strength in the heliocentric distance range 6-23 solar radii (Rs) by measuring the shock standoff distance and the radius of curvature of the flux rope during the 2008 March 25 coronal mass ejection imaged by white-light coronagraphs. Assuming the adiabatic index, we determine the Alfven Mach number, and hence the Alfven speed in the ambient medium using the measured shock speed. By measuring the upstream plasma density using polarization brightness images, we finally get the magnetic field strength upstream of the shock. The estimated magnetic field decreases from {approx}48 mG around 6 Rs to 8 mG at 23 Rs. The radial profile of the magnetic field can be described by a power law in agreement with other estimates at similar heliocentric distances.

Gopalswamy, Nat [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Yashiro, Seiji [Department of Physics, Catholic University of America, Washington, DC 20064 (United States)

2011-07-20T23:59:59.000Z

10

Magnetic Field Safety Training  

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

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

11

Magnetic Field Safety Magnetic Field Safety  

E-Print Network [OSTI]

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

McQuade, D. Tyler

12

Ion kinetic energy conservation and magnetic field strength constancy in multi-fluid solar wind Alfv\\'enic turbulence  

E-Print Network [OSTI]

We investigate properties of the plasma fluid motion in the large amplitude low frequency fluctuations of highly Alfv\\'enic fast solar wind. We show that protons locally conserve total kinetic energy when observed from an effective frame of reference comoving with the fluctuations. For typical properties of the fast wind, this frame can be reasonably identified by alpha particles, which, owing to their drift with respect to protons at about the Alfv\\'en speed along the magnetic field, do not partake in the fluid low frequency fluctuations. Using their velocity to transform proton velocity into the frame of Alfv\\'enic turbulence, we demonstrate that the resulting plasma motion is characterized by a constant absolute value of the velocity, zero electric fields, and aligned velocity and magnetic field vectors as expected for unidirectional Alfv\\'enic fluctuations in equilibrium. We propose that this constraint, via the correlation between velocity and magnetic field in Alfv\\'enic turbulence, is at the origin of ...

Matteini, L; Pantellini, F; Velli, M; Schwartz, S J

2015-01-01T23:59:59.000Z

13

National High Magnetic Field Laboratory: Museum of Electricity...  

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

strength of a magnetic field. He also made significant contributions to our understanding of the Earth's magnetic field. Related Electricity & Magnetism Pages Timeline: 1830 - 18...

14

Linear mode conversion of Langmuir/z-mode waves to radiation in plasmas with various magnetic field strength  

SciTech Connect (OSTI)

Linear mode conversion of Langmuir/z waves to electromagnetic radiation near the plasma and upper hybrid frequency in the presence of density gradients is potentially relevant to type II and III solar radio bursts, ionospheric radar experiments, pulsars, and continuum radiation for planetary magnetospheres. Here, we study mode conversion in warm, magnetized plasmas using a numerical electron fluid simulation code when the density gradient has a wide range of angle, ?, to the ambient magnetic field, B{sub 0}, for a range of incident Langmuir/z wavevectors. Our results include: (1) Left-handed polarized ordinary (oL) and right-handed polarized extraordinary (xR) mode waves are produced in various ranges of ? for ?{sub 0} = (?L/c){sup 1/3}(?{sub ce}/?) < 1.5, where ?{sub ce} is the (angular) electron cyclotron frequency, ? is the angular wave frequency, L is the length scale of the (linear) density gradient, and c is the speed of light; (2) the xR mode is produced most strongly in the range, 40° < ? < 60°, for intermediately magnetized plasmas with ?{sub 0} = 1.0 and 1.5, while it is produced over a wider range, 0° ? ? ? 90°, for weakly magnetized plasmas with ?{sub 0} = 0.1 and 0.7; (3) the maximum total conversion efficiencies for wave power from the Langmuir/z mode to radiation are of order 50%–99% and the corresponding energy conversion efficiencies are 5%–14% (depending on the adiabatic index ? and ? = T{sub e}/m{sub e}c{sup 2}, where T{sub e} is the electron temperature and m{sub e} is the electron) for various ?{sub 0}; (4) the mode conversion window becomes wider as ?{sub 0} and ? increase. Hence, the results in this paper confirm that linear mode conversion under these conditions can explain the weak total circular polarization of interplanetary type II and III solar radio bursts because a strong xR mode can be generated via linear mode conversion near ? ? 45°.

Kim, Eun-Hwa; Johnson, Jay R. [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)] [Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Cairns, Iver H. [School of Physics, University of Sydney, Sydney, New South Wales 2002 (Australia)] [School of Physics, University of Sydney, Sydney, New South Wales 2002 (Australia)

2013-12-15T23:59:59.000Z

15

Magnetic fields in the solar photosphere  

Science Journals Connector (OSTI)

...magnetoconvection in the quiet Sun. Filled contours show the temperature variations in a horizontal...Sanchez Almeida2003Quiet-Sun magnetic fields at high...Almeida, and F Kneer2006The distribution of quiet Sun magnetic field strengths...

2008-01-01T23:59:59.000Z

16

Optical sensor of magnetic fields  

DOE Patents [OSTI]

An optical magnetic field strength sensor for measuring the field strength of a magnetic field comprising a dilute magnetic semi-conductor probe having first and second ends, longitudinally positioned in the magnetic field for providing Faraday polarization rotation of light passing therethrough relative to the strength of the magnetic field. Light provided by a remote light source is propagated through an optical fiber coupler and a single optical fiber strand between the probe and the light source for providing a light path therebetween. A polarizer and an apparatus for rotating the polarization of the light is provided in the light path and a reflector is carried by the second end of the probe for reflecting the light back through the probe and thence through the polarizer to the optical coupler. A photo detector apparatus is operably connected to the optical coupler for detecting and measuring the intensity of the reflected light and comparing same to the light source intensity whereby the magnetic field strength may be calculated.

Butler, M.A.; Martin, S.J.

1986-03-25T23:59:59.000Z

17

THE GALACTIC MAGNETIC FIELD  

SciTech Connect (OSTI)

With this Letter, we complete our model of the Galactic magnetic field (GMF), by using the WMAP7 22 GHz total synchrotron intensity map and our earlier results to obtain a 13-parameter model of the Galactic random field, and to determine the strength of the striated random field. In combination with our 22-parameter description of the regular GMF, we obtain a very good fit to more than 40,000 extragalactic Faraday rotation measures and the WMAP7 22 GHz polarized and total intensity synchrotron emission maps. The data call for a striated component to the random field whose orientation is aligned with the regular field, having zero mean and rms strength Almost-Equal-To 20% larger than the regular field. A noteworthy feature of the new model is that the regular field has a significant out-of-plane component, which had not been considered earlier. The new GMF model gives a much better description of the totality of data than previous models in the literature.

Jansson, Ronnie; Farrar, Glennys R. [Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10003 (United States)

2012-12-10T23:59:59.000Z

18

Magnetic Fields in Clusters of Galaxies  

E-Print Network [OSTI]

A brief overview about our knowledge on galaxy cluster magnetic fields is provided. Emphasize is given to the mutual dependence of our knowledge on relativistic particles in galaxy clusters and the magnetic field strength. Furthermore, we describe efforts to measure magnetic field strengths, characteristic length-scales, and power-spectra with reliable accuracy. An interpretation of these results in terms of non-helical dynamo theory is given. If this interpretation turns out to be correct, the understanding of cluster magnetic fields is directly connected to our understanding of intra-cluster turbulence.

Torsten A. Ensslin; Corina Vogt; Christoph Pfrommer

2005-01-17T23:59:59.000Z

19

Magnetic Fields Analogous to electric field, a magnet  

E-Print Network [OSTI]

characteristic of elementary particles such as an electron #12;Magnetic Fields Magnetic field lines Direction;Magnetic Fields Magnetic field lines enter one end (south) of magnet and exit the other end (north) Opposite magnetic poles attract like magnetic poles repel #12;Like the electric field lines

Bertulani, Carlos A. - Department of Physics and Astronomy, Texas A&M University

20

Lesson Summary Students will learn about the magnetic fields of  

E-Print Network [OSTI]

Knowledge & Skills Understanding of: · Magnetic field lines · Magnetic field strength decreases class period Materials per student · NASA STERO mission story · Diagrams of the magnetic field linesLesson Summary Students will learn about the magnetic fields of the Sun and Earth. This activity

Mojzsis, Stephen J.

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


21

Some Comments About Correlations Between Magnetic Field and Velocity, Magnetic Field and Line Intensity in the Undisturbed Photosphere  

Science Journals Connector (OSTI)

Test cross-correlation functions between the magnetic field recordings and the sight-line velocity recordings with East and West relative ... the deviations of the absolute value of the magnetic-field strength |H

G. Y. Vassilyeva; A. K. Tchandaev

1968-01-01T23:59:59.000Z

22

Magnetic Field Viewing Cards  

Science Journals Connector (OSTI)

For some years now laminated cards containing a green magnetically sensitive film have been available from science education suppliers. When held near a magnet these cards appear dark green in regions where the field is perpendicular to the card and light green where the field is parallel to the card. The cards can be used to explore the magnetic field near a variety of magnets as well as near wire loops. In this paper we describe how to make these cards and how we have used them in our physics classrooms and labs.

Stephen Kanim; John R. Thompson

2005-01-01T23:59:59.000Z

23

Intrinsic Magnetic Fields  

Science Journals Connector (OSTI)

Emission theory of electromagnetic fields.—(1) Intrinsic magnetic field. The intrinsic magnetic field of a point charge is defined as that portion of the field which cannot be annihilated by the Lorentz transformation. It is shown that the intrinsic field can be represented by lines of force carried by the same moving elements as carry the electric field, and a potential is given for it. (2) Frequency of emission of moving elements. A relation between the frequency of emission of moving elements and the number of lines of force to a tube is deduced on the assumption that the latter number is the same for the electric and magnetic fields and that each moving element marks the intersection of an electric and magnetic line of force.

Leigh Page

1923-08-01T23:59:59.000Z

24

Iron Lines in Superstrong Magnetic Fields  

Science Journals Connector (OSTI)

The possibility of observing atomic lines in the x-ray spectra of strongly magnetized accreting neutron stars is discussed. For magnetic field strengths ranging from 1011-1014 G, both the energies and oscillator strengths of Fe XXVI lines are calculated quantitatively. These lines are expected to be highest in energy, and should dominate at source temperatures kT?10-30 keV.

H. Ruder; G. Wunner; H. Herold; J. Trümper

1981-06-29T23:59:59.000Z

25

Bipolar pulse field for magnetic refrigeration  

DOE Patents [OSTI]

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

Lubell, M.S.

1994-10-25T23:59:59.000Z

26

SP - 19 Magnetic Field Safety  

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

19 Page 1 Revision 02 August 6, 2007 NATIONAL HIGH MAGNETIC FIELD LABORATORY NHMFL FLORIDA STATE UNIVERSITY SAFETY PROCEDURE SP-19 MAGNETIC FIELD SAFETY ...

27

Rotational and magnetic shunt permanent magnet quadrupoles with variable magnetic strength  

SciTech Connect (OSTI)

Next Linear Collider (NLC) and Very Large Hadron Collider (VLHC) projects suppose to use permanent magnets as bending, focusing and correcting elements. Prototypes of two permanent magnet quadrupoles with variable strength were built and successfully tested in Fermilab. Quadrupoles have 12.7 mm aperture diameter, 100 T/m gradient with an adjustment range of 0 to -20%. Special designs provide high precision magnetic center stability during strength change. SmCo5 permanent magnet bricks were used in these prototypes. Rotational quadrupole consists of four sections. Two central sections are rotated in counter directions to adjust the strength. Magnetic shunt quadrupole design provides variable shunting of the magnetic flux. The numerical simulation, designs, measuring results are described.

Vladimir Kashikhin et al.

2002-03-28T23:59:59.000Z

28

Molecular Lines as Diagnostics of Solar and Stellar Magnetic Fields  

E-Print Network [OSTI]

Molecular Lines as Diagnostics of Solar and Stellar Magnetic Fields S.V. Berdyugina1, S.K. Solanki2 of different OH lines are reproduced without invoking any free parameters, except the magnetic field strength to significant improvements in the deduced magnetic field vector. Here we investigate how molecular lines can

Berdyugina, Svetlana

29

Two-dimensional oscillator in a magnetic field  

SciTech Connect (OSTI)

The energy and eigenstate spectrum of a charged particle in the electric field of a 2D anisotropic oscillator and in a uniform magnetic field is considered. The exact analytic solution to the problem is obtained for an arbitrary magnetic field strength. The characteristic features of variation of the energy spectrum depending on the magnetic field strength are analyzed. The results of this study are of interest for the quantum-mechanical theory of magnetism and can be used to simulate the magnetic properties of atoms and molecules.

Rebane, T. K., E-mail: trebane@mail.ri [St. Petersburg University, Fock Research Institute of Physics (Russian Federation)

2012-02-15T23:59:59.000Z

30

Stable magnetic fields in stellar interiors  

E-Print Network [OSTI]

We investigate the 50-year old hypothesis that the magnetic fields of the Ap stars are stable equilibria that have survived in these stars since their formation. With numerical simulations we find that stable magnetic field configurations indeed appear to exist under the conditions in the radiative interior of a star. Confirming a hypothesis by Prendergast (1956), the configurations have roughly equal poloidal and toroidal field strengths. We find that tori of such twisted fields can form as remnants of the decay of an unstable random initial field. In agreement with observations, the appearance at the surface is an approximate dipole with smaller contributions from higher multipoles, and the surface field strength can increase with the age of the star. The results of this paper were summarised by Braithwaite & Spruit (2004).

J. Braithwaite; A. Nordlund

2005-10-11T23:59:59.000Z

31

Magnetic Field Generation by Detonation Waves  

Science Journals Connector (OSTI)

A simple model is given for the spontaneous magnetic field generation by a detonation wave in condensed matter. The field is shown to arise from the noncollinearity of the thermal and electron density gradients near a medium boundary at the detonation shock front. The model allows calculation of approximate values for the field strength at the front and penetration ahead of the detonation wave. For typical explosive media interfaced by air the magnetic field is predicted to lie in the range 0.1 to 15 G.

Michael J. Frankel and Edward T. Toton

1979-12-10T23:59:59.000Z

32

National High Magnetic Field Laboratory Audio Dictionary: Magnetic...  

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

Links Magnets from Mini to Mighty Meet the Magnets How to Make an Electromagnet (audio slideshow) Compasses in Magnetic Fields (interactive tutorial) Magnetic Field Around a...

33

Magnetic-Field-Induced Assemblies of Cobalt Nanoparticles  

Science Journals Connector (OSTI)

8 Magnetic fields have also been used to create 2D assemblies of magnetic nanoparticles at the liquid?air interface9 and 1D assembled chains or 2D rings on solid substrates or TEM grids. ... A magnet (Fisher Scientific, Pittsburgh, PA) with a 0.05-Telsa magnetic field strength was placed near the side wall of the glass vial. ... The interparticle magnetic dipole?dipole couplings and the external coupling of the magnetic dipoles to the field favor linear chain growth along the magnetic-field flux lines. ...

Guangjun Cheng; Danilo Romero; Gerald T. Fraser; A. R. Hight Walker

2005-10-12T23:59:59.000Z

34

Wire codes, magnetic fields, and childhood cancer  

SciTech Connect (OSTI)

Childhood cancer has been modestly associated with wire codes, an exposure surrogate for power frequency magnetic fields, but less consistently with measured fields. The authors analyzed data on the population distribution of wire codes and their relationship with several measured magnetic field metrics. In a given geographic area, there is a marked trend for decreased prevalence from low to high wire code categories, but there are differences between areas. For average measured fields, there is a positive relationship between the mean of the distributions and wire codes but a large overlap among the categories. Better discrimination is obtained for the extremes of the measurement values when comparing the highest and the lowest wire code categories. Instability of measurements, intermittent fields, or other exposure conditions do not appear to provide a viable explanation for the differences between wire codes and magnetic fields with respect to the strength and consistency of their respective association with childhood cancer.

Kheifets, L.I.; Kavet, R.; Sussman, S.S. [Electric Power Research Inst., Palo Alto, CA (United States)] [Electric Power Research Inst., Palo Alto, CA (United States)

1997-05-01T23:59:59.000Z

35

Low field magnetic resonance imaging  

DOE Patents [OSTI]

A method and system of magnetic resonance imaging does not need a large homogenous field to truncate a gradient field. Spatial information is encoded into the spin magnetization by allowing the magnetization to evolve in a non-truncated gradient field and inducing a set of 180 degree rotations prior to signal acquisition.

Pines, Alexander (Berkeley, CA); Sakellariou, Dimitrios (Billancourt, FR); Meriles, Carlos A. (Fort Lee, NJ); Trabesinger, Andreas H. (London, GB)

2010-07-13T23:59:59.000Z

36

Results of magnetic field measurements of SPring-8 magnets  

SciTech Connect (OSTI)

Magnetic measurements have been performed for all dipoles, quadrupoles and sextupoles of the SPring-8 storage ring. The long flip coil and the rotating coil system were used for the measurements and they were good enough in measurement accuracy. Dispersion of the magnetic length and strength of the multipole fields were found to be within tolerable range for the three types of the magnets. The position of the fiducial points for alignment was measured in the accuracy of better than 20 {micro}m for all the quadrupoles and the sextupoles.

Ohnishi, J.; Kawakami, M.; Fujii, K.; Matsui, S.; Kumagai, N. [SPring-8, Hyogo (Japan)] [SPring-8, Hyogo (Japan)

1996-07-01T23:59:59.000Z

37

National High Magnetic Field Laboratory: Superconductors  

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

opposes the magnetic field generating the current. In a perfect diamagnet, the magnetic field lines produced exactly mirror those of the changing magnetic field that induce them,...

38

Variable-field permanent magnet dipole  

SciTech Connect (OSTI)

A new concept for a variable-field permanent-magnet dipole (VFPMD) has been designed, fabricated, and tested at Los Alamos. The VFPMD is a C-shaped sector magnet with iron poles separated by a large block of magnet material (SmCo). The central field can be continuously varied from 0.07 T to 0.3 T by moving an iron shunt closer or further away from the back of the magnet. The shunt is specially shaped to make the dependence of the dipole field strength on the shunt position as linear as possible. The dipole has a 2.8 cm high by 8 cm wide aperture with {approximately}10 cm long poles.

Barlow, D.B.; Kraus, R.H. Jr.; Meyer, R.E.

1993-10-01T23:59:59.000Z

39

PROTOSTELLAR DISK FORMATION ENABLED BY WEAK, MISALIGNED MAGNETIC FIELDS  

SciTech Connect (OSTI)

The gas from which stars form is magnetized, and strong magnetic fields can efficiently transport angular momentum. Most theoretical models of this phenomenon find that it should prevent formation of large (>100 AU), rotationally supported disks around most protostars, even when non-ideal magnetohydrodynamic (MHD) effects that allow the field and gas to decouple are taken into account. Using recent observations of magnetic field strengths and orientations in protostellar cores, we show that this conclusion is incorrect. The distribution of magnetic field strengths is very broad, and alignments between fields and angular momentum vectors within protostellar cores are essentially random. By combining the field strength and misalignment data with MHD simulations showing that disk formation is expected for both weak and misaligned fields, we show that these observations imply that we should expect disk fractions of {approx}10%-50% even when protostars are still deeply embedded in their parent cores, and even if the gas is governed by ideal MHD.

Krumholz, Mark R. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Crutcher, Richard M. [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W Green Street, Urbana, IL 61801 (United States); Hull, Charles L. H., E-mail: mkrumhol@ucsc.edu [Astronomy Department and Radio Astronomy Laboratory, University of California, Berkeley, CA 94720-3411 (United States)

2013-04-10T23:59:59.000Z

40

Magnetic-field-dosimetry system  

DOE Patents [OSTI]

A device is provided for measuring the magnetic field dose and peak field exposure. The device includes three Hall-effect sensors all perpendicular to each other, sensing the three dimensional magnetic field and associated electronics for data storage, calculating, retrieving and display.

Lemon, D.K.; Skorpik, J.R.; Eick, J.L.

1981-01-21T23:59:59.000Z

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


41

Bound states in a strong magnetic field  

SciTech Connect (OSTI)

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

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

2013-03-25T23:59:59.000Z

42

High magnetic field processing of liquid crystalline polymers  

DOE Patents [OSTI]

A process of forming bulk articles of oriented liquid crystalline thermoset material, the material characterized as having an enhanced tensile modulus parallel to orientation of an applied magnetic field of at least 25 percent greater than said material processed in the absence of a magnetic field, by curing a liquid crystalline thermoset precursor within a high strength magnetic field of greater than about 2 Tesla, is provided, together with a resultant bulk article of a liquid crystalline thermoset material, said material processed in a high strength magnetic field whereby said material is characterized as having a tensile modulus parallel to orientation of said field of at least 25 percent greater than said material processed in the absence of a magnetic field.

Smith, M.E.; Benicewicz, B.C.; Douglas, E.P.

1998-11-24T23:59:59.000Z

43

CHAPTER 3. STRUCTURE OF MAGNETIC FIELDS 1 Structure of Magnetic  

E-Print Network [OSTI]

CHAPTER 3. STRUCTURE OF MAGNETIC FIELDS 1 Chapter 3 Structure of Magnetic Fields Many of the most interesting plasmas are permeated by or imbedded in magnetic fields.1 As shown in Fig. 3.1, the magnetic field properties of magnetic fields in plasmas can be discussed without specifying a model for the plasma

Callen, James D.

44

The CP2 star ff 2 CVn: radial velocity, magnetic field,  

E-Print Network [OSTI]

with the areas of the magnetic poles (in case of Cr) as with the regions where the magnetic field lines haveThe CP2 star ff 2 CVn: radial velocity, magnetic field, and element distribution G. Hildebrandt­ metric observations made in Tautenburg the radial velocity and the strength of the magnetic field

45

Nano- and Microstructures of Magnetic Field-Guided Maghemite Nanoparticles in Diblock Copolymer Films  

Science Journals Connector (OSTI)

The magnetic behavior of the hybrid films was probed at different temperatures for two orthogonal directions (with the line-shaped particle aggregates parallel and perpendicular to the magnetic field). ... The observations indicate that well-aligned, highly oriented metal-oxide lines can be obtained at low magnetic field strengths, such as 149 G, rather than at higher magnetic fields. ... Magnet-polymer (Magpol) composites have an interesting ability to undergo large strains in response to an external magnetic field. ...

Yuan Yao; Ezzeldin Metwalli; Martin A. Niedermeier; Matthias Opel; Chen Lin; Jing Ning; Jan Perlich; Stephan V. Roth; Peter Müller-Buschbaum

2014-03-12T23:59:59.000Z

46

Magnetic field in a finite toroidal domain  

SciTech Connect (OSTI)

The magnetic field structure in a domain surrounded by a closed toroidal magnetic surface is analyzed. It is shown that ergodization of magnetic field lines is possible even in a regular field configuration (with nonvanishing toroidal component). A unified approach is used to describe magnetic fields with nested toroidal (possibly asymmetric) flux surfaces, magnetic islands, and ergodic field lines.

Ilgisonis, V. I.; Skovoroda, A. A., E-mail: skovorod@nfi.kiae.r [Russian Research Centre Kurchatov Institute (Russian Federation)

2010-05-15T23:59:59.000Z

47

RESOLVED MAGNETIC FIELD MAPPING OF A MOLECULAR CLOUD USING GPIPS  

SciTech Connect (OSTI)

We present the first resolved map of plane-of-sky magnetic field strength for a quiescent molecular cloud. GRSMC 45.60+0.30 subtends 40 Multiplication-Sign 10 pc at a distance of 1.88 kpc, masses 16,000 M{sub Sun }, and exhibits no star formation. Near-infrared background starlight polarizations were obtained for the Galactic Plane Infrared Polarization Survey using the 1.8 m Perkins telescope and the Mimir instrument. The cloud area of 0.78 deg{sup 2} contains 2684 significant starlight polarizations for Two Micron All Sky Survey matched stars brighter than 12.5 mag in the H band. Polarizations are generally aligned with the cloud's major axis, showing an average position angle dispersion of 15 {+-} 2 Degree-Sign and polarization of 1.8 {+-} 0.6%. The polarizations were combined with Galactic Ring Survey {sup 13}CO spectroscopy and the Chandrasekhar-Fermi method to estimate plane-of-sky magnetic field strengths, with an angular resolution of 100 arcsec. The average plane-of-sky magnetic field strength across the cloud is 5.40 {+-} 0.04 {mu}G. The magnetic field strength map exhibits seven enhancements or 'magnetic cores'. These cores show an average magnetic field strength of 8.3 {+-} 0.9 {mu}G, radius of 1.2 {+-} 0.2 pc, intercore spacing of 5.7 {+-} 0.9 pc, and exclusively subcritical mass-to-flux ratios, implying their magnetic fields continue to suppress star formation. The magnetic field strength shows a power-law dependence on gas volume density, with slope 0.75 {+-} 0.02 for n{sub H{sub 2}} {>=}10 cm{sup -3}. This power-law index is identical to those in studies at higher densities, but disagrees with predictions for the densities probed here.

Marchwinski, Robert C.; Pavel, Michael D.; Clemens, Dan P., E-mail: robmarch@bu.edu, E-mail: pavelmi@bu.edu, E-mail: clemens@bu.edu [Institute for Astrophysical Research, Boston University, 725 Commonwealth Ave, Boston, MA 02215 (United States)

2012-08-20T23:59:59.000Z

48

National High Magnetic Field Laboratory - Visualizing Field Lines...  

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

Now You See It: Visualizing Field Lines Try This At Home The magnetic field is the area around the magnet where the magnetic forces act. Actually, magnets are made up of many, many...

49

Determination of Electric-Field, Magnetic-Field, and Electric...  

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

Electric-Field, Magnetic-Field, and Electric-Current Distributions of Infrared Optical Antennas: A Near-Field Determination of Electric-Field, Magnetic-Field, and Electric-Current...

50

The Sun's global magnetic field  

Science Journals Connector (OSTI)

...the plasma in the Sun's atmosphere...representation of the Sun's large-scale...high density and temperature contrast between...the density and temperature distributions found in the global...magnetic fields on the Sun and other stars...

2012-01-01T23:59:59.000Z

51

Neutron in Strong Magnetic Fields  

E-Print Network [OSTI]

Relativistic world-line Hamiltonian for strongly interacting 3q systems in magnetic field is derived from the path integral for the corresponding Green's function. The neutral baryon Hamiltonian in magnetic field obeys the pseudomomentum conservation and allows a factorization of the c.m. and internal motion. The resulting expression for the baryon mass in magnetic field is written explicitly with the account of hyperfine, OPE and OGE (color Coulomb) interaction. The neutron mass is fast decreasing with magnetic field, losing 1/2 of its value at eB~0.25 GeV^2 and is nearly zero at eB~0.5 GeV^2. Possible physical consequences of the calculated mass trajectory of the neutron, M_n(B), are presented and discussed.

M. A. Andreichikov; B. O. Kerbikov; V. D. Orlovsky; Yu. A. Simonov

2013-12-08T23:59:59.000Z

52

Mitigated-force carriage for high magnetic field environments  

SciTech Connect (OSTI)

A carriage for high magnetic field environments includes a first work-piece holding means for holding a first work-piece, the first work-piece holding means being disposed in an operable relationship with a work-piece processing magnet having a magnetic field strength of at least 1 Tesla. The first work-piece holding means is further disposed in operable connection with a second work-piece holding means for holding a second work-piece so that, as the first work-piece is inserted into the magnetic field, the second work-piece is simultaneously withdrawn from the magnetic field, so that an attractive magnetic force imparted on the first work-piece offsets a resistive magnetic force imparted on the second work-piece.

Ludtka, Gerard M; Ludtka, Gail M; Wilgen, John B; Murphy, Bart L

2014-05-20T23:59:59.000Z

53

High Field Magnetic Resonance Facility  

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

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

54

National High Magnetic Field Laboratory: An Introduction to Magnets...  

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

resistive magnet is here at the Magnet Lab: It can generate a sustained magnetic field of 35 tesla. (Were not counting here our world-record hybrid magnet or the stronger,...

55

National High Magnetic Field Laboratory: An Introduction to Magnets...  

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

is a magnet); opposite poles attract, like poles repel. In all magnets, the magnetic field lines run from south to north, and these fields are what produce forces on other...

56

Magnetic field lines for a flux tube  

Science Journals Connector (OSTI)

Equations for the magnetic field components in a two dimensional cylindrically symmetric ... in a simple case, solved. The resulting magnetic configuration possesses a strong magnetic field in a thin tube below a...

C. D. C. Steele; Rekha Jain

1993-05-01T23:59:59.000Z

57

Development of Tumor Targeting Bioprobes (111In-Chimeric L6 Monoclonal Antibody Nanoparticles) for Alternating Magnetic Field Cancer Therapy  

Science Journals Connector (OSTI)

...Development and characterization of magnetic cationic liposomes in vitro...the strength of an external magnetic field (EMF). For this reason...perinuclear localization of magnetic cationic liposomes with all cell lines. Higher cell growth inhibition...

Sally J. DeNardo; Gerald L. DeNardo; Laird A. Miers; Arutselvan Natarajan; Alan R. Foreman; Cordula Gruettner; Grete N. Adamson; and Robert Ivkov

2005-10-01T23:59:59.000Z

58

Nematic order of model goethite nanorods in a magnetic field  

E-Print Network [OSTI]

We explore the nematic order of model goethite nanorods in an external magnetic field within Onsager-Parsons density functional theory. The goethite rods are represented by monodisperse, charged spherocylinders with a permanent magnetic moment along the rod main axis, forcing the particles to align parallel to the magnetic field at low field strength. The intrinsic diamagnetic susceptibility anisometry of the rods is negative which leads to a preferred perpendicular orientation at higher field strength. It is shown that these counteracting effects may give rise to intricate phase behavior, including a pronounced stability of biaxial nematic order and the presence of reentrant phase transitions and demixing phenomena. The effect of the applied field on the nematic-to-smectic transition will also be addressed.

H. H. Wensink; G. J. Vroege

2005-01-18T23:59:59.000Z

59

National High Magnetic Field Laboratory Slideshow: Seeing Magnetic...  

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

more about magnets You can start here with a straightforward rundown. Compasses in Magnetic Fields Experiment with the compass in this tutorial to see how it responds to...

60

High Field Magnet R&D |Superconducting Magnet Division  

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

High Field Magnet R&D High Field Magnet R&D The Superconducting Magnet Division is developing advanced magnet designs and magnet-related technologies for high field accelerator magnets. We are currently working on magnets for three inter-related programs: High Field Magnets for Muon Collider Papers, Presentations Common Coil Magnets Papers, Presentations Interaction Region Magnets Papers, Presentations High Temperature Superconductor (HTS) Magnets Papers, Presentations This is part of a multi-lab superconducting magnet development program for new accelerator facilities that would be part of the U.S. High Energy Physics program. These programs (@BNL, @FNAL, @LBNL) are quite complimentary to each other, so that magnet designs and technologies developed at one laboratory can be easily transferred to another. The BNL

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


61

Recycling of the Solar Corona's Magnetic Field  

Science Journals Connector (OSTI)

Magnetic fields play a dominant role in the atmospheres of the Sun and other Sun-like stars. Outside sunspot regions, the photosphere of the so-called quiet Sun contains myriads of small-scale magnetic concentrations, with strengths ranging from the detection limit of ~1016 Mx up to ~3 ? 1020 Mx. The tireless motion of these magnetic flux concentrations, along with the continual appearance and disappearance of opposite-polarity pairs of fluxes, releases a substantial amount of energy that may be associated with a whole host of physical processes in the solar corona, not least the enigma of coronal heating. We find here that the timescale for magnetic flux to be remapped in the quiet-Sun corona is, surprisingly, only 1.4 hr (around 1/10 of the photospheric flux recycling time), implying that the quiet-Sun corona is far more dynamic than previously thought. Besides leading to a fuller understanding of the origins of magnetically driven phenomena in our Sun's corona, such a process may also be crucial for the understanding of stellar atmospheres in general.

R. M. Close; C. E. Parnell; D. W. Longcope; E. R. Priest

2004-01-01T23:59:59.000Z

62

Stellar model atmospheres with magnetic line blanketing. III. The role of magnetic field inclination  

E-Print Network [OSTI]

Context. See abstract in the paper. Aims. In the last paper of this series we study the effects of the magnetic field, varying its strength and orientation, on the model atmosphere structure, the energy distribution, photometric colors and the hydrogen Balmer line profiles. We compare with the previous results for an isotropic case in order to understand whether there is a clear relation between the value of the magnetic field angle and model changes, and to study how important the additional orientational information is. Also, we examine the probable explanation of the visual flux depressions of the magnetic chemically peculiar stars in the context of this work. Methods. We calculated one more grid of the model atmospheres of magnetic A and B stars for different effective temperatures (Teff=8000K, 11000K, 15000K), magnetic field strengths (B=0, 5, 10, 40 kG) and various angles of the magnetic field (Omega=0-90 degr) with respect to the atmosphere plane. We used the LLmodels code which implements a direct method for line opacity calculation, anomalous Zeeman splitting of spectral lines, and polarized radiation transfer. Results. We have not found significant changes in model atmosphere structure, photometric and spectroscopic observables or profiles of hydrogen Balmer lines as we vary the magnetic field inclination angle Omega. The strength of the magnetic field plays the main role in magnetic line blanketing. We show that the magnetic field has a clear relation to the visual flux depressions of the magnetic CP stars. Conclusions. See abstract in the paper.

S. A. Khan; D. V. Shulyak

2006-07-20T23:59:59.000Z

63

Relaxing the bounds on primordial magnetic seed fields  

Science Journals Connector (OSTI)

We point out that the lower bound on the primordial magnetic field required to seed the galactic dynamo is significantly relaxed in an open universe or in a universe with a positive cosmological constant. In such universes, the increased age of galaxies gives a dynamo mechanism more time to amplify a small initial field. It is shown that, for reasonable cosmological parameters, primordial seed fields of strength 10-30 G or less at the time of galaxy formation could explain observed galactic magnetic fields. As a consequence, mechanisms of primordial magnetic seed-field generation that have previously been ruled out could well be viable. We also comment on the implications of the observation of micro-Gauss magnetic fields in galaxies at high redshift.

Anne-Christine Davis; Matthew Lilley; Ola Törnkvist

1999-06-23T23:59:59.000Z

64

Free energies in magnetic fields  

Science Journals Connector (OSTI)

The partition function is calculated exactly at low temperatures and dimensionality one in the presence of a magnetic field for ferromagnetic systems of n-component unit vectors with nearest-neighbor interactions. For n=2 the free energy is proportional to the lowest eigenvalue of Mathieu's equation. Asymptotic solutions for n=3 are also given.

Jorge V. José

1976-09-01T23:59:59.000Z

65

Separation of magnetic field lines  

SciTech Connect (OSTI)

The field lines of magnetic fields that depend on three spatial coordinates are shown to have a fundamentally different behavior from those that depend on two coordinates. Unlike two-coordinate cases, a flux tube in a magnetic field that depends on all three spatial coordinates that has a circular cross section at one location along the tube characteristically has a highly distorted cross section at other locations. In an ideal evolution of a magnetic field, the current densities typically increase. Crudely stated, if the current densities increase by a factor {sigma}, the ratio of the long to the short distance across a cross section of a flux tube characteristically increases by e{sup 2{sigma}}, and the ratio of the longer distance to the initial radius increases as e{sup {sigma}}. Electron inertia prevents a plasma from isolating two magnetic field structures on a distance scale shorter than c/{omega}{sub pe}, which is about 10 cm in the solar corona, and reconnection must be triggered if {sigma} becomes sufficiently large. The radius of the sun, R{sub Circled-Dot-Operator }=7 Multiplication-Sign 10{sup 10}cm is about e{sup 23} times larger, so when {sigma} Greater-Than-Or-Equivalent-To 23, two lines separated by c/{omega}{sub pe} at one location can be separated by the full scale of any magnetic structures in the corona at another. The conditions for achieving a large exponentiation, {sigma}, are derived, and the importance of exponentiation is discussed.

Boozer, Allen H. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)

2012-11-15T23:59:59.000Z

66

Conduction of Electricity by Dielectric Liquids at High Field Strengths  

Science Journals Connector (OSTI)

The conductivity of highly purified heptane has been measured between optical flats at field strengths up to 600,000 volts per cm at temperatures ranging from - 190°C to 20°C. Electrode separations down to 0.005 cm were used in order to minimize the effect of space charge and ionic recombination. It is concluded that electronic or collision processes are unlikely as the source of high field conductivity in heptane and probably most other liquid dielectrics as well. It is suggested that the highly nonconducting dielectric liquids should be included as extreme cases in the general class of weak electrolytes. The presence of appreciable conductivity under high electric fields is ascribed to the lowering of the energy of the hydrogen bond by the applied field.

H. J. Plumley

1941-01-15T23:59:59.000Z

67

The motion of magnetic field lines  

Science Journals Connector (OSTI)

The definition and applications of the motion of magnetic lines of force are reviewed and illustrated. First ... aid to describing the evolution of a known magnetic field. It is next shown that a known velocity field

David P. Stern

1966-11-01T23:59:59.000Z

68

National High Magnetic Field Laboratory - Drawing Field Lines...  

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

A Portrait of Magnetism: Drawing Field Lines Try This At Home Magnets have two poles; the field lines spread out from the north pole and circle back around to the south pole. In...

69

Rotating copper plasmoid in external magnetic field  

SciTech Connect (OSTI)

Effect of nonuniform magnetic field on the expanding copper plasmoid in helium and argon gases using optical emission spectroscopy and fast imaging is presented. We report a peculiar oscillatory rotation of plasmoid in magnetic field and argon ambient. The temporal variation and appearance of the dip in the electron temperature show a direct evidence of the threading and expulsion of the magnetic field lines from the plasmoid. Rayleigh Taylor instability produced at the interface separating magnetic field and plasma is discussed.

Pandey, Pramod K.; Thareja, Raj K. [Department of Physics, Indian Institute of Technology Kanpur, Uttar Pradesh 208 016 (India)

2013-02-15T23:59:59.000Z

70

Magnetic fields of neutron stars in X-ray binaries  

E-Print Network [OSTI]

A substantial fraction of the known neutron stars resides in X-ray binaries -- systems in which one compact object accretes matter from a companion star. Neutron stars in X-ray binaries have magnetic fields among the highest found in the Universe, spanning at least the range from $\\sim10^8$ to several 10$^{13}$ G. The magnetospheres around these neutron stars have a strong influence on the accretion process, which powers most of their emission. The magnetic field intensity and geometry, are among the main factors responsible for the large variety of spectral and timing properties observed in the X-ray energy range, making these objects unique laboratories to study the matter behavior and the radiation processes in magnetic fields unaccessible on Earth. In this paper we review the main observational aspects related to the presence of magnetic fields in neutron star X-ray binaries and some methods that are used to estimate their strength.

Revnivtsev, Mikhail

2014-01-01T23:59:59.000Z

71

Primordial magnetic fields and formation of molecular hydrogen  

E-Print Network [OSTI]

We study the implications of primordial magnetic fields for the thermal and ionization history of the post-recombination era. In particular we compute the effects of dissipation of primordial magnetic fields owing to ambipolar diffusion and decaying turbulence in the intergalactic medium (IGM) and the collapsing halos and compute the effects of the altered thermal and ionization history on the formation of molecular hydrogen. We show that, for magnetic field strengths in the range $2 \\times 10^{-10} {\\rm G} \\la B_0 \\la 2 \\times 10^{-9} {\\rm G}$, the molecular hydrogen fraction in IGM and collapsing halo can increase by a factor 5 to 1000 over the case with no magnetic fields. We discuss the implication of the increased molecular hydrogen fraction on the radiative transfer of UV photons and the formation of first structures in the universe.

Shiv K Sethi; Biman B. Nath; Kandaswamy Subramanian

2008-04-22T23:59:59.000Z

72

CORONAL MAGNETIC FIELD MEASUREMENTS THROUGH GYRORESONANCE EMISSION  

E-Print Network [OSTI]

Chapter 5 CORONAL MAGNETIC FIELD MEASUREMENTS THROUGH GYRORESONANCE EMISSION Stephen M. White This article reviews the use of gyroresonance emission at radio wavelengths to measure coronal magnetic fields. Keywords: Sun, solar corona, solar magnetic fields, solar radio emission Introduction Since the realization

White, Stephen

73

A strong, highly-tilted interstellar magnetic field near the Solar System  

Science Journals Connector (OSTI)

... hydrogen was not taken into account. Here we report measurements of the deflection of the solar wind plasma flows in the heliosheath to determine the magnetic field strength and orientation in ... We conclude that the interstellar medium field is turbulent or has a distortion in the solar vicinity. The local interstellar medium magnetic field (BISM) is one of the key ...

M. Opher; F. Alouani Bibi; G. Toth; J. D. Richardson; V. V. Izmodenov; T. I. Gombosi

2009-12-24T23:59:59.000Z

74

Magnetic monopole and the nature of the static magnetic field  

E-Print Network [OSTI]

We investigate the factuality of the hypothetical magnetic monopole and the nature of the static magnetic field. It is shown from many aspects that the concept of the massive magnetic monopoles clearly is physically untrue. We argue that the static magnetic field of a bar magnet, in fact, is the static electric field of the periodically quasi-one-dimensional electric-dipole superlattice, which can be well established in some transition metals with the localized d-electron. This research may shed light on the perfect unification of magnetic and electrical phenomena.

Xiuqing Huang

2008-12-10T23:59:59.000Z

75

Permanent Magnet Ecr Plasma Source With Magnetic Field Optimization  

DOE Patents [OSTI]

In a plasma-producing device, an optimized magnet field for electron cyclotron resonance plasma generation is provided by a shaped pole piece. The shaped pole piece adjusts spacing between the magnet and the resonance zone, creates a convex or concave resonance zone, and decreases stray fields between the resonance zone and the workpiece. For a cylindrical permanent magnet, the pole piece includes a disk adjacent the magnet together with an annular cylindrical sidewall structure axially aligned with the magnet and extending from the base around the permanent magnet. The pole piece directs magnetic field lines into the resonance zone, moving the resonance zone further from the face of the magnet. Additional permanent magnets or magnet arrays may be utilized to control field contours on a local scale. Rather than a permeable material, the sidewall structure may be composed of an annular cylindrical magnetic material having a polarity opposite that of the permanent magnet, creating convex regions in the resonance zone. An annular disk-shaped recurve section at the end of the sidewall structure forms magnetic mirrors keeping the plasma off the pole piece. A recurve section composed of magnetic material having a radial polarity forms convex regions and/or magnetic mirrors within the resonance zone.

Doughty, Frank C. (Plano, TX); Spencer, John E. (Plano, TX)

2000-12-19T23:59:59.000Z

76

Magnetic particles confined in a modulated channel: structural transitions tunable by tilting a magnetic field  

E-Print Network [OSTI]

The ground state of colloidal magnetic particles in a modulated channel are investigated as function of the tilt angle of an applied magnetic field. The particles are confined by a parabolic potential in the transversal direction while in the axial direction a periodic substrate potential is present. By using Monte Carlo (MC) simulations, we construct a phase diagram for the different crystal structures as a function of the magnetic field orientation, strength of the modulated potential and the commensurability factor of the system. Interestingly, we found first and second order phase transitions between different crystal structures, which can be manipulated by the orientation of the external magnetic field. A re-entrant behavior is found between two- and four-chain configurations, with continuous second order transitions. Novel configurations are found consisting of frozen in solitons. By changing the orientation and/or strength of the magnetic field and/or the strength and the spatial frequency of the periodic substrate potential, the system transits through different phases.

J. E. Galván-Moya; D. Lucena; W. P. Ferreira; F. M. Peeters

2014-01-03T23:59:59.000Z

77

Magnetic line trapping and effective transport in stochastic magnetic fields  

Science Journals Connector (OSTI)

The transport of collisional particles in stochastic magnetic fields is studied using the decorrelation trajectory method. The nonlinear effect of magnetic line trapping is considered together with particle collisions. The running diffusion coefficient is determined for arbitrary values of the statistical parameters of the stochastic magnetic field and of the collisional velocity. The effect of the magnetic line trapping is determined. New anomalous diffusion regimes are found.

M. Vlad; F. Spineanu; J. H. Misguich; R. Balescu

2003-02-07T23:59:59.000Z

78

Presented by the National High Magnetic Field Laboratory  

E-Print Network [OSTI]

Magnets These lines show the magnetic field created by the bar magnet. Look, this magnetic field looks like an apple! Field Lines #12;Scientists at the Magnet Lab use a special kind of magnet calledPresented by the National High Magnetic Field Laboratory Learning About Name #12;A magnet

Weston, Ken

79

Magnet strength fluctuations in the SSC (Superconducting Super Collider) lattice: Part 2, Frequency modulation  

SciTech Connect (OSTI)

This is a continuation of SSC-N-305. SSC-N-305 examined the effects of field strength modulation, when the modulation frequency (f/sub mod/) was equal to zero (i.e., current offset). The objective of this study is to examine the effect of field strength modulation with modulation frequencies other than zero. To this end, the tracking routine TEAPOT is modified to simulate frequency modulation of the current output from the 10 main SSC magnet power supplies. The amplitude (A/sub i/) and phase (phi/sub i/) of the modulation for the i/sup th/ power supply are chosen randomly. Effects of bore tube shielding are included only when studying 60 Hz modulation frequency. Bore tube shielding is due to the copper coating on the bore tube walls. This coating modifies the amplitude and phase of the modulation inside the bore tube. The bore tube is more effective at shielding the dipole field and it becomes most effective as the modulation frequency increases. 3 refs., 10 figs., 3 tabs.

Goderre, G.P.

1987-06-01T23:59:59.000Z

80

Superconducting strip in an oblique magnetic field  

Science Journals Connector (OSTI)

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

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

2004-07-30T23:59:59.000Z

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


81

Unique topological characterization of braided magnetic fields  

SciTech Connect (OSTI)

We introduce a topological flux function to quantify the topology of magnetic braids: non-zero, line-tied magnetic fields whose field lines all connect between two boundaries. This scalar function is an ideal invariant defined on a cross-section of the magnetic field, and measures the average poloidal magnetic flux around any given field line, or the average pairwise crossing number between a given field line and all others. Moreover, its integral over the cross-section yields the relative magnetic helicity. Using the fact that the flux function is also an action in the Hamiltonian formulation of the field line equations, we prove that it uniquely characterizes the field line mapping and hence the magnetic topology.

Yeates, A. R. [Department of Mathematical Sciences, Durham University, Durham DH1 3LE (United Kingdom); Hornig, G. [Division of Mathematics, University of Dundee, Dundee DD1 4HN (United Kingdom)

2013-01-15T23:59:59.000Z

82

Scaling the energy conversion rate from magnetic field reconnection to different bodies  

E-Print Network [OSTI]

Scaling the energy conversion rate from magnetic field reconnection to different bodies F. S. Mozer reconnection is often invoked to explain electromagnetic energy conversion in planetary magnetospheres, stellar in these bodies, it is important to understand energy conversion as a function of magnetic field strength

California at Berkeley, University of

83

National High Magnetic Field Laboratory: Team Tesla - How we...  

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

resistive magnets (also called electromagnets or Bitter magnets), ranging in magnetic field from 20 tesla to 45 tesla, each in its own little cell. These magnets get so...

84

Magnetic Field Switching of Nanoparticles between Orthogonal Microfluidic Channels  

Science Journals Connector (OSTI)

Permanent magnets have also been used together with integrated current lines to divert micrometer-sized magnetic beads within a microfluidic “Y” geometry,15 and antibody-coated microbeads immobilized in a microfluidic device were used in immunoassays for the sensitive detection of corresponding antigens. ... 35-37 The top piece (?5 mm thick) was formed by casting the PDMS (ratio of PDMS to curing agent was 15:1) over an aluminum master with a line measuring 320 ?m high and 200 ?m wide. ... Magnetic fields were applied using a NdFeB permanent magnet (circumference, 2.5 cm; height, 2.5 cm; field strength at edge, ?0.7 T; Engineered Concepts, Birmingham, AL). ...

Andrew H. Latham; Anand N. Tarpara; Mary Elizabeth Williams

2007-06-23T23:59:59.000Z

85

Magnetic field perturbations in the systems where only poloidal magnetic field is present*  

E-Print Network [OSTI]

. Introduction of a weak regular toroidal magnetic field reduces radial excursions of the field lines. Possible #12;6 The equations for the perturbed magnetic field line are: dr dJ = dBr +dB1r B0 +dBJ ; dz dJ = d1 Magnetic field perturbations in the systems where only poloidal magnetic field is present* D

86

National High Magnetic Field Laboratory: Museum of Electricity...  

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

chemistry. Related Electricity & Magnetism Pages Interactive Java Tutorials: Magnetic Field Lines Around a Wire Interactive Java Tutorials: Magnetic Field Lines Around a Wire, II...

87

National High Magnetic Field Laboratory: Museum of Electricity...  

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

of the Earths magnetic field to the research community. Related Electricity & Magnetism Pages Interactive Java Tutorials: Compasses in Magnetic Fields Interactive Java...

88

Primordial magnetic fields in false vacuum inflation  

Science Journals Connector (OSTI)

We show that, during false vacuum inflation, a primordial magnetic field can be created sufficiently strong to seed the galactic dynamo and generate the observed galactic magnetic fields. Considering the inflaton-dominated regime, our field is produced by the Higgs-field gradients, resulting from a grand unified phase transition. The evolution of the field is followed from its creation through to the epoch of structure formation, subject to the relevant constraints. We find that it is possible to create a magnetic field of sufficient magnitude, provided the phase transition occurs during the final five e-foldings of the inflationary period.

Anne-Christine Davis and Konstantinos Dimopoulos

1997-06-15T23:59:59.000Z

89

National High Magnetic Field Laboratory - Publications  

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

Lett. Physica B Physica C Physica E Polymer Polymer J. Proc. Physical Phenomena at High Magnetic Fields - IV Protein Science PROTEINS: Structure, Function and Genetics Rapid...

90

Enhancement of accelerating field of microwave cavities by magnetic insulation  

SciTech Connect (OSTI)

Limitations on the maximum achievable accelerating gradient of microwave cavities can strongly influence the performance, length, and cost of particle accelerators. Gradient limitations are widely believed to be initiated by electron emission from the cavity surfaces. Here, we show that the deleterious effects of field emission are effectively suppressed by applying a tangential magnetic field to the cavity walls. With the aid of numerical simulations we compute the field strength required to insulate an 805 MHz cavity and estimate the cavity's tolerances to typical experimental errors such as magnet misalignments and positioning errors. Then, we review an experimental program, currently under progress, to further study the concept. Finally, we report on two specific examples that illustrate the feasibility of magnetic insulation into prospective particle accelerator applications.

Stratakis, D.; Gallardo, J.; Palmer, R.B.

2011-04-15T23:59:59.000Z

91

Rotational and magnetic field instabilities in neutron stars  

SciTech Connect (OSTI)

In this short review we present recent results on the dynamics of neutron stars and their magnetic fields. We discuss the progress that has been made, during the last 5 years, in understanding the rotational instabilities with emphasis to the one due to the f-mode, the possibility of using gravitational wave detection in constraining the parameters of neutron stars and revealing the equation of state as well as the detectability of gravitational waves produced during the unstable phase of a neutron star’s life. In addition we discuss the dynamics of extremely strong magnetic fields observed in a class of neutron stars (magnetars). Magnetic fields of that strength are responsible for highly energetic phenomena (giant flares) and we demonstrate that the analysis of the emitted electromagnetic radiation can lead in constraining the parameters of neutron stars. Furthermore, we present our results from the study of such violent phenomena in association with the emission of gravitational radiation.

Kokkotas, Kostas D. [Theoretical Astrophysics, IAAT, Eberhard Karls University of Tübingen, Tübingen 72076 (Germany)

2014-01-14T23:59:59.000Z

92

Biaxial testing of high strength carbon fiber composite cylinders for pulsed magnet reinforcement  

E-Print Network [OSTI]

Biaxial testing of high strength carbon fiber composite cylinders for pulsed magnet reinforcement N A methodology is introduced to test carbon-fiber-reinforced, hoop-wound composite cylinders for their biaxial. Testing of actual pulsed magnets to ascertain design change effects of composite reinforcement schemes

Garmestani, Hamid

93

Constructing the Coronal Magnetic Field By Correlating Parameterized Magnetic Field Lines With Observed Coronal Plasma Structures  

Science Journals Connector (OSTI)

A method is presented for constructing the coronal magnetic field from photospheric magnetograms and observed coronal loops. A set of magnetic field lines generated from magnetogram data is parameterized and ... ...

G. Allen Gary; David Alexander

1999-05-01T23:59:59.000Z

94

The National High Magnetic Field Laboratory: Condensed Matter Science in Continuous Magnetic Fields  

Science Journals Connector (OSTI)

The National High Magnetic Field Laboratory (NHMFL) operates three facilities ... Tallahassee, Florida, the ultra-low-temperature high-magnetic-field facilities are located at the University ... scientific achiev...

M. D. Bird; J. E. Crow; P. Schlottmann

2003-10-01T23:59:59.000Z

95

Experimental investigation on heat transfer characteristics of magnetic fluid flow around a fine wire under the influence of an external magnetic field  

SciTech Connect (OSTI)

Experimental investigation is conducted to get insight into convective heat transfer features of the aqueous magnetic fluid flow over a fine wire under the influence of an external magnetic field. The convective heat transfer coefficient of the aqueous magnetic fluid flow around the heated wire is measured in both the uniform magnetic field and the magnetic field gradient. The effects of the external magnetic field strength and its orientation on the thermal behaviors of the magnetic fluids are analyzed. The experimental results show that the external magnetic field is a vital factor that affects the convective heat transfer performances of the magnetic fluids and the control of heat transfer processes of a magnetic fluid flow can be possible by applying an external magnetic field. (author)

Li, Qiang; Xuan, Yimin [School of Power Engineering, Nanjing University of Science and Technology, 200 Xiao Ling Wei, Nanjing 210094 (China)

2009-04-15T23:59:59.000Z

96

Cryogenic Magnet Could Open New Fields  

Science Journals Connector (OSTI)

Now that its cryogenic superconducting magnet is commercially available (C&EN, Jan. 15, page 43), Westinghouse Electric expects the magnet to open up new areas of high-field magnet research with possible use in magnetohydrodynamics, thermonuclear fusion, and cryogenic devices. ...

1962-01-22T23:59:59.000Z

97

Magnetic field decay in model SSC dipoles  

SciTech Connect (OSTI)

We have observed that some of our model SSC dipoles have long time constant decays of the magnetic field harmonics with amplitudes large enough to result in significant beam loss, if they are not corrected. The magnets were run at constant current at the SSC injection field level of 0.3 tesla for one to three hours and changes in the magnetic field were observed. One explanation for the observed field decay is time dependent superconductor magnetization. Another explanation involves flux creep or flux flow. Data are presented on how the decay changes with previous flux history. Similar magnets with different Nb-Ti filament spacings and matrix materials have different long time field decay. A theoretical model using proximity coupling and flux creep for the observed field decay is discussed. 10 refs., 5 figs., 2 tabs.

Gilbert, W.S.; Althaus, R.F.; Barale, P.J.; Benjegerdes, R.W.; Green, M.A.; Green, M.I.; Scanlan, R.M.

1988-08-01T23:59:59.000Z

98

Graphene Nanoribbon in Sharply Localized Magnetic Fields  

E-Print Network [OSTI]

We study the effect of a sharply localized magnetic field on the electron transport in a strip (ribbon) of graphene sheet, which allows to give results for the transmission and reflection probability through magnetic barriers. The magnetic field is taken as a single and double delta type localized functions, which are treated later as the zero width limit of gaussian fields. For both field configurations, we evaluate analytically and numerically their transmission and reflection coefficients. The possibility of spacial confinement due to the inhomogeneous field configuration is also investigated.

Abdulaziz D. Alhaidari; Hocine Bahlouli; Abderrahim El Mouhafid; Ahmed Jellal

2011-03-21T23:59:59.000Z

99

Two charges on plane in a magnetic field: II. Moving neutral quantum system across a magnetic field  

E-Print Network [OSTI]

The moving neutral system of two Coulomb charges on a plane subject to a constant magnetic field $B$ perpendicular to the plane is considered. It is shown that the composite system of finite total mass is bound for any center-of-mass momentum $P$ and magnetic field strength; the energy of the ground state is calculated accurately using a variational approach. Their accuracy is cross-checked in a Lagrange-mesh method for $B=1$ a.u. and in a perturbation theory at small $B$ and $P$. The constructed trial function has the property of being a uniform approximation of the exact eigenfunction. For a Hydrogen atom and a Positronium a double perturbation theory in $B$ and $P$ is developed and the first corrections are found algebraically. A phenomenon of a sharp change of energy behavior for a certain center-of-mass momentum and a fixed magnetic field is indicated.

M. A. Escobar-Ruiz; A. V. Turbiner

2014-07-10T23:59:59.000Z

100

High concentration ferronematics in low magnetic fields  

E-Print Network [OSTI]

We investigated experimentally the magneto-optical and dielectric properties of magnetic-nanoparticle-doped nematic liquid crystals (ferronematics). Our studies focus on the effect of the very small orienting bias magnetic field $B_{bias}$, and that of the nematic director pretilt at the boundary surfaces in our systems sensitive to low magnetic fields. Based on the results we assert that $B_{bias}$ is not necessarily required for a detectable response to low magnetic fields, and that the initial pretilt, as well as the aggregation of the nanoparticles play an important (though not yet explored enough) role.

T. Tóth-Katona; P. Salamon; N. Éber; N. Tomašovi?ová; Z. Mitróová; P. Kop?anský

2014-09-05T23:59:59.000Z

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


101

Magnetic field outflows from active galactic nuclei  

Science Journals Connector (OSTI)

We examine several models of injecting magnetic fields into clusters of galaxies from active galactic nuclei, which are the powerful outflows associated with supermassive black holes in the centers of clusters. Shown are magnetic field lines after six ... Keywords: scientific visualization

David Pugmire; Paul Sutter; Paul Ricker; Hsiang-Yi (Karen) Yang; George Foreman

2011-11-01T23:59:59.000Z

102

Local magnetic fields in disordered metals  

Science Journals Connector (OSTI)

We show that in a disordered metal the local magnetic fields generated by the magnetic-field-induced orbital-electron currents will fluctuate strongly in magnitude and direction. We argue that this phenomenon should be reflected by a noticeable inhomogeneous broadening of NMR lines and analyze its dependence on system geometry and temperature.

R. A. Serota and A. Yu. Zyuzin

1993-06-01T23:59:59.000Z

103

Hydrogen atom moving across a magnetic field  

Science Journals Connector (OSTI)

A hydrogen atom moving across a magnetic field is considered in a wide region of magnitudes of magnetic field and atom momentum. We solve the Schrödinger equation of the system numerically using an imaginary time method and find wave functions of the lowest states of atom. We calculate the energy and the mean electron-nucleus separation as a function of atom momentum and magnetic field. All the results obtained could be summarized as a phase diagram on the “atom-momentum – magnetic-field” plane. There are transformations of wave-function structure at critical values of atom momentum and magnetic field that result in a specific behavior of dependencies of energy and mean interparticle separation on the atom momentum P. We discuss a transition from the Zeeman regime to the high magnetic field regime. A qualitative analysis of the complicated behavior of wave functions vs P based on the effective potential examination is given. We analyze a sharp transition at the critical momentum from a Coulomb-type state polarized due to atom motion to a strongly decentered (Landau-type) state at low magnetic fields. A crossover occurring at intermediate magnetic fields is also studied.

Yu. E. Lozovik and S. Yu. Volkov

2004-08-23T23:59:59.000Z

104

Energy of magnetic moment of superconducting current in magnetic field  

E-Print Network [OSTI]

The energy of magnetic moment of the persistent current circulating in superconducting loop in an externally produced magnetic field is not taken into account in the theory of quantization effects because of identification of the Hamiltonian with the energy. This identification misleads if, in accordance with the conservation law, the energy of a state is the energy expended for its creation. The energy of magnetic moment is deduced from a creation history of the current state in magnetic field both in the classical and quantum case. But taking this energy into account demolishes the agreement between theory and experiment. Impartial consideration of this problem discovers the contradiction both in theory and experiment.

V. L. Gurtovoi; A. V. Nikulov

2014-12-22T23:59:59.000Z

105

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

E-Print Network [OSTI]

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

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

2014-06-26T23:59:59.000Z

106

Permanent magnet edge-field quadrupole  

DOE Patents [OSTI]

Planar permanent magnet edge-field quadrupoles for use in particle accelerating machines and in insertion devices designed to generate spontaneous or coherent radiation from moving charged particles are disclosed. The invention comprises four magnetized rectangular pieces of permanent magnet material with substantially similar dimensions arranged into two planar arrays situated to generate a field with a substantially dominant quadrupole component in regions close to the device axis. 10 figs.

Tatchyn, R.O.

1997-01-21T23:59:59.000Z

107

Magnetic fields in Neutron Stars  

E-Print Network [OSTI]

Isolated neutron stars show a diversity in timing and spectral properties, which has historically led to a classification in different sub-classes. The magnetic field plays a key role in many aspects of the neutron star phenomenology: it regulates the braking torque responsible for their timing properties and, for magnetars, it provides the energy budget for the outburst activity and high quiescent luminosities (usually well above the rotational energy budget). We aim at unifying this observational variety by linking the results of the state-of-the-art 2D magneto-thermal simulations with observational data. The comparison between theory and observations allows to place two strong constraints on the physical properties of the inner crust. First, strong electrical currents must circulate in the crust, rather than in the star core. Second, the innermost part of the crust must be highly resistive, which is in principle in agreement with the presence of a novel phase of matter so-called nuclear pasta phase.

Viganò, Daniele; Miralles, Juan A; Rea, Nanda

2015-01-01T23:59:59.000Z

108

Proto-Neutron Star Winds with Magnetic Fields and Rotation  

E-Print Network [OSTI]

We solve the 1D neutrino-heated non-relativistic MHD wind problem for conditions that range from slowly rotating (spin period P > 10 ms) protoneutron stars (PNSs) with surface field strengths typical of radio pulsars (B winds are relativistic. We then quantify the effects of rotation and magnetic fields on the mass loss, energy loss, and r-process nucleosynthesis in PNS winds. We describe the evolution of PNS winds through the Kelvin-Helmholtz cooling epoch, emphasizing the transition between (1) thermal neutrino-driven, (2) non-relativistic magnetically-dominated, and (3) relativistic magnetically-dominated outflows. We find that proto-magnetars with P ~ 1 ms and B > 10^15 G drive relativistic winds with luminosities, energies, and Lorentz factors (magnetization sigma ~ 0.1-1000) consistent with those required to produce long duration gamma-ray bursts and hyper-energetic supernovae (SNe). A significant fraction of the rotational energy may be extracted in only a few seconds, sufficiently rapidly to alter the asymptotic energy of the SN remnant, its morphology, and, potentially, its nucleosynthetic yield. Winds from PNSs with more modest rotation periods (2 - 10 ms) and with magnetar-strength fields produce conditions significantly more favorable for the r-process than winds from slowly rotating PNSs. Lastly, we show that energy and momentum deposition by convectively-excited waves further increase the likelihood of successful r-process in PNS winds.

Brian D. Metzger; Todd A. Thompson; Eliot Quataert

2006-08-30T23:59:59.000Z

109

The Magnetic Field in the Solar Atmosphere  

E-Print Network [OSTI]

This publication provides an overview of magnetic fields in the solar atmosphere with the focus lying on the corona. The solar magnetic field couples the solar interior with the visible surface of the Sun and with its atmosphere. It is also responsible for all solar activity in its numerous manifestations. Thus, dynamic phenomena such as coronal mass ejections and flares are magnetically driven. In addition, the field also plays a crucial role in heating the solar chromosphere and corona as well as in accelerating the solar wind. Our main emphasis is the magnetic field in the upper solar atmosphere so that photospheric and chromospheric magnetic structures are mainly discussed where relevant for higher solar layers. Also, the discussion of the solar atmosphere and activity is limited to those topics of direct relevance to the magnetic field. After giving a brief overview about the solar magnetic field in general and its global structure, we discuss in more detail the magnetic field in active regions, the quie...

Wiegelmann, Thomas; Solanki, Sami K

2014-01-01T23:59:59.000Z

110

Warm inflation in presence of magnetic fields  

SciTech Connect (OSTI)

We present preliminary results on the possible effects that primordial magnetic fields can have for a warm inflation scenario, based on global supersymmetry, with a new-inflation-type potential. This work is motivated by two considerations: first, magnetic fields seem to be present in the universe on all scales which rises de possibility that they could also permeate the early universe; second, the recent emergence of inflationary models where the inflaton is not assumed to be isolated but instead it is taken as an interacting field, even during the inflationary expansion. The effects of magnetic fields are included resorting to Schwinger's proper time method.

Piccinelli, Gabriella [Centro Tecnológico, FES Aragón, Universidad Nacional Autónoma de México, Avenida Rancho Seco S/N, Bosques de Aragón, Nezahualcóyotl, Estado de México 57130 (Mexico)] [Centro Tecnológico, FES Aragón, Universidad Nacional Autónoma de México, Avenida Rancho Seco S/N, Bosques de Aragón, Nezahualcóyotl, Estado de México 57130 (Mexico); Sánchez, Ángel [Department of Physics, University of Texas at El Paso, El Paso, Texas 79968 (United States)] [Department of Physics, University of Texas at El Paso, El Paso, Texas 79968 (United States); Ayala, Alejandro; Mizher, Ana Julia [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apartado Postal 70-543, México Distrito Federal 04510 (Mexico)] [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Apartado Postal 70-543, México Distrito Federal 04510 (Mexico)

2013-07-23T23:59:59.000Z

111

Sub-100 nm Confinement of Magnetic Nanoparticles Using Localized Magnetic Field Gradients  

E-Print Network [OSTI]

that generate large magnetic gradients. In a homogeneous magnetic field, the field lines are parallel; that is, then the field lines converge into the ferromagnet. This convergence forms a shallow magnetic field gradient, to minimize the magnetic potential energy, the field lines exiting one magnet converge into the other magnet

Prentiss, Mara

112

Turbulent diffusion with rotation or magnetic fields  

E-Print Network [OSTI]

The turbulent diffusion tensor describing the evolution of the mean concentration of a passive scalar is investigated for forced turbulence either in the presence of rotation or a magnetic field. With rotation the Coriolis force causes a sideways deflection of the flux of mean concentration. Within the magnetohydrodynamics approximation there is no analogous effect from the magnetic field because the effects on the flow do not depend on the sign of the field. Both rotation and magnetic fields tend to suppress turbulent transport, but this suppression is weaker in the direction along the magnetic field. Turbulent transport along the rotation axis is not strongly affected by rotation, except on shorter length scales, i.e. when the scale of the variation of the mean field becomes comparable with the scale of the energy-carrying eddied.

Brandenburg, Axel; Vasil, Geoffrey M

2009-01-01T23:59:59.000Z

113

External-field-free magnetic biosensor  

SciTech Connect (OSTI)

In this paper, we report a magnetic nanoparticle (MNP) detection scheme without the presence of any external magnetic field. The proposed magnetic sensor uses a patterned groove structure within the sensor so that no external magnetic field is needed to magnetize the MNPs. An example is given based on a giant magnetoresistance (GMR) sensing device with a spin valve structure. For this structure, the detection of MNPs located inside the groove and near the free layer is demonstrated under no external magnetic field. Micromagnetic simulations are performed to calculate the signal to noise level of this detection scheme. A maximum signal to noise ratio (SNR) of 18.6?dB from one iron oxide magnetic nanoparticle with 8?nm radius is achieved. As proof of concept, this external-field-free GMR sensor with groove structure of 200?nm?×?200?nm is fabricated using a photo and an electron beam integrated lithography process. Using this sensor, the feasibility demonstration of the detection SNR of 9.3?dB is achieved for 30??l magnetic nanoparticles suspension (30?nm iron oxide particles, 1?mg/ml). This proposed external-field-free sensor structure is not limited to GMR devices and could be applicable to other magnetic biosensing devices.

Li, Yuanpeng; Wang, Yi; Klein, Todd; Wang, Jian-Ping, E-mail: jpwang@umn.edu [Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

2014-03-24T23:59:59.000Z

114

Ultracold Plasma Expansion in a Magnetic Field  

Science Journals Connector (OSTI)

We measure the expansion of an ultracold plasma across the field lines of a uniform magnetic field. We image the ion distribution by extracting the ions with a high-voltage pulse onto a position-sensitive detector. Early in the lifetime of the plasma (magnetic field (up to 70 G). We observe that the expansion velocity scales as B-1/2, explained by a nonlinear ambipolar diffusion model with anisotropic diffusion in two different directions.

X. L. Zhang; R. S. Fletcher; S. L. Rolston; P. N. Guzdar; M. Swisdak

2008-06-13T23:59:59.000Z

115

Enhanced density and magnetic fields in interstellar OH masers  

E-Print Network [OSTI]

Aims: We have observed the 6030 and 6035 MHz transitions of OH in high-mass star-forming regions to obtain magnetic field estimates in both maser emission and absorption. Methods: Observations were taken with the Effelsberg 100 m telescope. Results: Our observations are consistent with previous results, although we do detect a new 6030 MHz maser feature near -70 km/s in the vicinity of W3(OH). In absorption we obtain a possible estimate of -1.1 +/- 0.3 mG for the average line-of-sight component of the magnetic field in the absorbing OH gas in K3-50 and submilligauss upper limits for the line-of-sight field strength in DR 21 and W3. Conclusions: These results indicate that the magnetic field strength in the vicinity of OH masers is higher than that of the surrounding, non-masing material, which in turn suggests that the density of masing OH regions is higher than that of their surroundings.

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

2006-08-04T23:59:59.000Z

116

National High Magnetic Field Laboratory - Magnets and Materials...  

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

W.D. and Weijers, H.W., Helium gas bubble trapped in liquid helium in high magnetic field, Appl. Phys. Lett., 104, 133511 (2014) read online 2 Bai, H.; Marshall, W.S.; Bird,...

117

On Space Quantization in Time Varying Magnetic Fields  

Science Journals Connector (OSTI)

The transitions between states of different space quantization which take place when an atom is passed through a weak inhomogeneous magnetic field are calculated by approximate methods taking into account the coupling between the nucleus and the orbital electrons. Two types of field are considered, namely, the field introduced by Majorana and the one introduced by Güttinger. For the Majorana field a discussion of the cases I arbitrary J=12, J arbitrary I=12, and I and J arbitrary with explicit application to the nitrogen atom is given. For the Güttinger field the general equations are set up for a field of any strength and are then applied to the case I=J=12.

Lloyd Motz and M. E. Rose

1936-08-15T23:59:59.000Z

118

ASYMMETRIC DIFFUSION OF MAGNETIC FIELD LINES  

SciTech Connect (OSTI)

Stochasticity of magnetic field lines is important for particle transport properties. Magnetic field lines separate faster than diffusively in turbulent plasma, which is called superdiffusion. We discovered that this superdiffusion is pronouncedly asymmetric, so that the separation of field lines along the magnetic field direction is different from the separation in the opposite direction. While the symmetry of the flow is broken by the so-called imbalance or cross-helicity, the difference between forward and backward diffusion is not directly due to imbalance, but a non-trivial consequence of both imbalance and non-reversibility of turbulence. The asymmetric diffusion perpendicular to the mean magnetic field entails a variety of new physical phenomena, such as the production of parallel particle streaming in the presence of perpendicular particle gradients. Such streaming and associated instabilities could be significant for particle transport in laboratory, space, and astrophysical plasmas.

Beresnyak, Andrey [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2013-04-20T23:59:59.000Z

119

Magnetic Field Effects on Copper Electrolysis  

Science Journals Connector (OSTI)

Four different magnets were used to supply a static magnetic field to the cell during the various electrochemical experiments. ... A Halbach cylinder with a fixed static field of 0.5 T in a 54 mm bore or a 48 mm bore Multimag38 permanent magnet system capable of delivering variable fields in the range 0?1.0 T in any direction transverse to the bore was used for the lower field experiments. ... The Lorentz force, F?L, arises from the motion of charge across lines of magnetic flux, whereas the electrokinetic force, F?E, results from the stress on the charge carriers in the diffuse double layer under the influence of a nonelectrostatic field, E??, parallel to the electrode surface. ...

G. Hinds; F. E. Spada; J. M. D. Coey; T. R. Ní Mhíocháin; M. E. G. Lyons

2001-09-12T23:59:59.000Z

120

Magnetic fields from second-order interactions  

E-Print Network [OSTI]

It is well known that when two types of perturbations interact in cosmological perturbation theory, the interaction may lead to the generation of a third type. In this article we discuss the generation of magnetic fields from such interactions. We determine conditions under which the interaction of a first-order magnetic field with a first-order scalar-or vector-, or tensor-perturbations would lead to the generation of second order magnetic field. The analysis is done in a covariant-index-free approach, but could be done in the standard covariant indexed-approach.

Bob Osano

2014-03-21T23:59:59.000Z

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


121

Electrical properties of chain microstructure magnetic emulsions in magnetic field  

E-Print Network [OSTI]

The work deals with the experimental study of the emulsion whose dispersion medium is a magnetic fluid while the disperse phase is formed by a glycerin-water mixture. It is demonstrated that under effect of a magnetic field chain aggregates form from the disperse phase drops. Such emulsion microstructure change affects its macroscopic properties. The emulsion dielectric permeability and specific electrical conductivity have been measured. It is demonstrated that under the effect of relatively weak external magnetic fields (~ 1 kA/m) the emulsion electrical parameters may change several fold. The work theoretically analyzes the discovered regularities of the emulsion electrical properties.

Arthur Zakinyan; Yuri Dikansky; Marita Bedzhanyan

2014-02-05T23:59:59.000Z

122

Reverse?field reciprocity for conducting specimens in magnetic fields  

Science Journals Connector (OSTI)

A new static?electromagnetic reciprocity principle is presented extending ordinary resistive reciprocity to the case of nonzero magnetic fields by requiring the magnetic field to be reversed when the reciprocal measurement is made. The principle is supported by measurements on various types of specimens including those which exhibit the quantum?Hall effect. A derivation using elementary electromagnetic theory shows that the principle will hold provided only that the specimen is electrically linear (Ohmic) and that the Onsager form for the conductivity tensor applies throughout. The principle has important implications for electrical measurements on semiconductors in applied?magnetic fields.

H. H. Sample; W. J. Bruno; S. B. Sample; E. K. Sichel

1987-01-01T23:59:59.000Z

123

Magnetic Vortex Core Reversal by Low-Field Excitations  

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

Magnetic Vortex Core Reversal by Low-Field Excitations Print In micrometer-sized magnetic thin films, the magnetization typically adopts an in-plane, circular configuration known...

124

National High Magnetic Field Laboratory: Museum of Electricity...  

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

high-tech field, gradually being replaced by semiconductors. Related Electricity & Magnetism Pages Magnetic Core Memory: Interactive Java Tutorial Magnetic core memory was...

125

Experiments on Magnetic-Field-Line Reconnection  

Science Journals Connector (OSTI)

In a very large laboratory plasma the process of magnetic-field-line reconnection has been diagnosed carefully. The temporal evolution of a narrow (?3c?pe) neutral layer with Petschek slow shocks is observed. Electrostatic fields are found to be as important as induced electric fields.

R. L. Stenzel and W. Gekelman

1979-04-16T23:59:59.000Z

126

Review: Magnetic fields of O stars  

E-Print Network [OSTI]

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

Wade, G A

2014-01-01T23:59:59.000Z

127

Magnetic Field Measurements and Analysis For an Aladdin Dipole Magnet  

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

Field Measurements and Analysis Field Measurements and Analysis For an Aladdin Dipole Magnet by Kenneth M. Thompson Electromagnetic Technology Program Argonne National Laboratory Argonne, 1L 60439 L8-40 November 21, 1985 Table of Contents Summary i A. Introduction *..*.**.***.....****...**.*..*...*..***.......*..... 1 1. Magnet Description 2. Measuring System 3. Data Descriptions 1 1 3 B. Equipment **********************.***.******.*************..******* 5 1. Probe Positioning System a. Description b. Calibration 2. Field Probe a. Calibration b. Probe Center 1. Method 2. Repeatability c. Hall Gaussmeter Parameters 3. Auxiliary Probes 4. Optical Alignment Equipment 5. Power Supply 6. Magnet Cooling Water System 7. Support a. Magnet b. Manipulator 5 5 7 7 8 9 9 9 10 10 13 13

128

MRS photodiode in strong magnetic field  

SciTech Connect (OSTI)

The experimental results on the performance of the MRS (Metal/Resistor/Semiconductor) photodiode in the strong magnetic field of 4.4T, and the possible impact of the quench of the magnet at 4.5T on sensor's operation are reported.

Beznosko, D.; Blazey, G.; Dyshkant, A.; Francis, K.; Kubik, D.; Rykalin, V.; /Northern Illinois U.; Tartaglia, M.A.; /Fermilab; Zutshi, v.; /Northern Illinois U.

2004-12-01T23:59:59.000Z

129

Magnetic Field Lines in Fusion Plasmas  

Science Journals Connector (OSTI)

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

Sadrilla S. Abdullaev

2006-01-01T23:59:59.000Z

130

National High Magnetic Field Laboratory - Electron Interaction...  

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

c). Plot of the CNT sample conductance versus the gate voltage and the axial magnetic field. A dark arrow indicates the value of B0 , where the energy gap has a minimum (metallic...

131

National High Magnetic Field Laboratory: Superconducting Wire  

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

of the particles has an effect on the pinning along various directions of magnetic field lines. The conductive capacity of 2G HTS wire is similarly affected by the...

132

Static High Magnetic Fields and Materials Science  

Science Journals Connector (OSTI)

Like temperature or pressure, the magnetic field is one of the important thermodynamic parameters that are used to change the inner energies of materials. Materials are essentially composed of atomic nuclei an...

M. Motokawa; K. Watanabe; F. Herlach

2002-01-01T23:59:59.000Z

133

National High Magnetic Field Laboratory: Museum of Electricity...  

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

Pages Interactive Java Tutorials: Galvanometer Interactive Java Tutorials: Magnetic Field Lines Around a Wire, I Interactive Java Tutorials: Magnetic Field Lines Around a Wire,...

134

Laminated magnet field coil sheath  

DOE Patents [OSTI]

A method for manufacturing a magnetic cable trim coil in a sheath assembly for use in a cryogenic particle accelerator. A precisely positioned pattern of trim coil turns is bonded to a flexible substrate sheath that is capable of withstanding cryogenic operating conditions. In the method of the invention the flexible substrate sheath, with the trim coil pattern precisely location relative to a bore tube assembly of an accelerator and is then bonded to the bore tube with a tape suitable for cryogenic application. The resultant assembly can be readily handled and installed within an iron magnet yoke assembly of a suitable cryogenic particle accelerator. 1 fig.

Skaritka, J.R.

1987-05-15T23:59:59.000Z

135

The Onset of Ion Heating During Magnetic Reconnection with a Strong Guide Field  

E-Print Network [OSTI]

The onset of the acceleration of ions during magnetic reconnection is explored via particle-in-cell simulations in the limit of a strong ambient guide field that self-consistently and simultaneously follow the motions of protons and $\\alpha$ particles. Heating parallel to the local magnetic field during reconnection with a guide field is strongly reduced compared with the reconnection of anti-parallel magnetic fields. The dominant heating of thermal ions during guide field reconnection results from pickup behavior of ions during their entry into reconnection exhausts and dominantly produces heating perpendicular rather than parallel to the local magnetic field. Pickup behavior requires that the ion transit time across the exhaust boundary (with a transverse scale of the order of the ion sound Larmor radius) be short compared with the ion cyclotron period. This translates into a threshold in the strength of reconnecting magnetic field that favors the heating of ions with high mass-to-charge. A simulation with ...

Drake, J F

2014-01-01T23:59:59.000Z

136

Sensitivity Reach of the Neutron EDM Experiment: The Electric Field Strength  

SciTech Connect (OSTI)

The search for an electric dipole moment of the neutron tests physics beyond the Standard Model such as new sources of CP-violation and Supersymmetry. The nEDM experiment aims to improve the sensitivity on the current limit of the electric dipole moment of the neutron to <10{sup -27} e{center_dot}cm. The experiment will use a flux of Ultra Cold Neutrons (UCNs) produced and stored in a bath of superfluid He-II. A change in precession frequency is expected for a non-zero EDM when an electric field is applied parallel and antiparallel to a magnetic field across the neutron storage cell. A dominant parameter in terms of reducing the statistical uncertainty of this measurement is the strength of the applied electric field. An experiment to measure if superfluid He-II can sustain up to 50 kV/cm for a volume and electrode spacings comparable to the nEDM experiment has been constructed at Los Alamos National Laboratory. It consists in a large-area parallel plate capacitor immersed in a 200 liter central volume inside a suitable cryostat that in turn is connected to a dilution refrigerator unit. A description of test runs and the status of the experiment is presented.

Hennings-Yeomans, R.; Cooper, M.; Currie, S. A.; Makela, M. F.; Ramsey, J. C.; Tajima, S.; Womack, T. L. [Physics Division, Los Alamos National Laboratory, Los Alamos NM 87545 (United States); Long, J. C. [Department of Physics, Indiana University, 727 E. Third St. Bloomington, IN 47405-7105 (United States); Stanislaus, S. [Department of Physics and Astronomy, Valparaiso University, Valparaiso, IN 46383 (United States)

2010-08-04T23:59:59.000Z

137

Quiet Sun Magnetic Field Measurements Based on Lines with Hyperfine Structure  

E-Print Network [OSTI]

The Zeeman pattern of MnI lines is sensitive to hyperfine structure (HFS) and, they respond to hG magnetic field strengths differently from the lines used in solar magnetometry. This peculiarity has been employed to measure magnetic field strengths in quiet Sun regions. However, the methods applied so far assume the magnetic field to be constant in the resolution element. The assumption is clearly insufficient to describe the complex quiet Sun magnetic fields, biasing the results of the measurements. We present the first syntheses of MnI lines in realistic quiet Sun model atmospheres. The syntheses show how the MnI lines weaken with increasing field strength. In particular, kG magnetic concentrations produce NnI 5538 circular polarization signals (Stokes V) which can be up to two orders of magnitude smaller than the weak magnetic field approximation prediction. Consequently, (1) the polarization emerging from an atmosphere having weak and strong fields is biased towards the weak fields, and (2) HFS features characteristic of weak fields show up even when the magnetic flux and energy are dominated by kG fields. For the HFS feature of MnI 5538 to disappear the filling factor of kG fields has to be larger than the filling factor of sub-kG fields. Stokes V depends on magnetic field inclination according to the simple consine law. Atmospheres with unresolved velocities produce asymmetric line profiles, which cannot be reproduced by simple one-component model atmospheres. The uncertainty of the HFS constants do not limit the use of MnI lines for magnetometry.

J. Sanchez Almeida; B. Viticchie; E. Landi Degl'Innocenti; F. Berrilli

2007-10-29T23:59:59.000Z

138

In Situ Magnetic Field-Assisted Low Temperature Atmospheric Growth of GaN Nanowires via the Vapor–Liquid–Solid Mechanism  

Science Journals Connector (OSTI)

The magnetic field strength was controlled by varying the distance between the magnet and the substrate to ultimately have three different magnetic field strengths of ?0.25, 0.43, and 0.80 T, as measured by a Gauss meter at room temperature. ... The vertical dotted lines show three clear peaks I1, I2, and I3 (with increasing energy). ... One hundred percent magnetic alignment of nanostructures to the imposed magnetic fields was achieved by applying a low external magnetic field of 200 Oe. ...

Jun Sik Kim; Bhaskar Chandra Mohanty; Chan Su Han; Seung Jun Han; Gwang Heon Ha; Liwei Lin; Yong Soo Cho

2013-10-11T23:59:59.000Z

139

Generation of Magnetic Field on the Accretion Disk around a Proto-First-Star  

E-Print Network [OSTI]

The generation process of magnetic field around a proto-first-star is studied. Utilizing the recent numerical result of proto-first-star formation based upon the radiation hydrodynamics simulations, we assess the magnetic field strength generated by the radiative force and the Biermann battery effect. We find that magnetic field of \\sim 10^{-9} G is generated on the surface of the accretion disk around the proto-first-star. The field strength on the accretion disk is smaller by two orders of magnitude than the critical value, above which the gravitational fragmentation of the disk is suppressed. Thus, the generated seed magnetic field hardly affect the dynamics of on-site first star formation directly, unless efficient amplification process is taken into consideration. We also find that the generated magnetic field is continuously blown out from the disk on the outflows to the poles, that are driven by the thermal pressure of photoheated gas. The strength of the diffused magnetic field in low density regions ...

Shiromoto, Yuki; Hosokawa, Takashi

2014-01-01T23:59:59.000Z

140

Hyperon bulk viscosity in strong magnetic fields  

SciTech Connect (OSTI)

We study the bulk viscosity of neutron star matter including {lambda} hyperons in the presence of quantizing magnetic fields. Relaxation time and bulk viscosity due to both the nonleptonic weak process involving {lambda} hyperons and direct Urca processes are calculated here. In the presence of a strong magnetic field of 10{sup 17} G, the hyperon bulk viscosity coefficient is reduced, whereas bulk viscosity coefficients due to direct Urca processes are enhanced compared with their field free cases when many Landau levels are populated by protons, electrons, and muons.

Sinha, Monika; Bandyopadhyay, Debades [Theory Division and Centre for Astroparticle Physics, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700064 (India)

2009-06-15T23:59:59.000Z

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


141

Circumstellar Magnetic Field Diagnostics from Line Polarization  

E-Print Network [OSTI]

Given that dynamically significant magnetic fields in at least some massive stars have now been measured, our contribution addresses the question, to what extent can fields be directly detected in circumstellar gas? The question speaks directly to the very interesting topic of line-driving physics coupled with magnetized plasmas, and how this coupling produces structure in the wind flow. We focus our attention on weak-field diagnostics. These come in two main types: the Hanle effect, which pertains to coherence effects for linear polarization from line scattering, and the weak longitudinal Zeeman effect, which pertains to circular polarization in lines.

Richard Ignace; Kenneth G. Gayley

2007-08-14T23:59:59.000Z

142

Ambipolar Diffusion in a Magnetic Field  

Science Journals Connector (OSTI)

Diffusion of ions in a plasma across a magnetic field is shown to be not ambipolar in character in most arc experiments. Owing to the highly anisotropic conductivity of the medium, the ions diffuse across the field at their own intrinsic rate. Space-charge neutralization is maintained by slight adjustments of the currents in the direction of the magnetic field lines. The discrepancy between theory and experiment noted by Bohm is thus resolved and no additional mechanisms, such as plasma oscillations, need be postulated.

Albert Simon

1955-04-15T23:59:59.000Z

143

Resonance scattering formalism for the hydrogen lines in the presence of magnetic and electric fields  

Science Journals Connector (OSTI)

We derive a formalism for the computation of resonance-scattering polarization of hydrogen lines in the presence of simultaneous magnetic and electric fields, within a framework of the quantum theory of polarized line formation in the limit of complete frequency redistribution and of collisionless regime. Quantum interferences between fine-structure levels are included in this formalism. In the presence of a magnetic field, these interferences affect, together with the magnetic Hanle effect, the polarization of the atomic levels. In the presence of an electric field, interferences between distinct orbital configurations are also induced, further affecting the polarization of the hydrogen levels. In turn, the electric field is expected to affect the polarization of the atomic levels (electric Hanle effect), in a way analogous to the magnetic Hanle effect. We find that the simultaneous action of electric and magnetic fields give rise to complicated patterns of polarization and depolarization regimes, for varying geometries and field strengths.

Roberto Casini

2005-06-22T23:59:59.000Z

144

Abrupt Longitudinal Magnetic Field Changes in Flaring Active Regions  

Science Journals Connector (OSTI)

We characterize the changes in the longitudinal photospheric magnetic field during 38 X-class and 39 M-class flares within 65° of disk center using 1 minute GONG magnetograms. In all 77 cases, we identify at least one site in the flaring active region where clear, permanent, stepwise field changes occurred. The median duration of the field changes was about 15 minutes and was approximately equal for X-class and for M-class flares. The absolute values of the field changes ranged from the detection limit of ~10 G to as high as ~450 G in two exceptional cases. The median value was 69 G. Field changes were significantly stronger for X-class than for M-class flares and for limb flares than for disk-center flares. Longitudinal field changes less than 100 G tended to decrease longitudinal field strengths, both close to disk center and close to the limb, while field changes greater than 100 G showed no such pattern. Likewise, longitudinal flux strengths tended to decrease during flares. Flux changes, particularly net flux changes near disk center, correlated better than local field changes with GOES peak X-ray flux. The strongest longitudinal field and flux changes occurred in flares observed close to the limb. We estimate the change of Lorentz force associated with each flare and find that this is large enough in some cases to power seismic waves. We find that longitudinal field decreases would likely outnumber increases at all parts of the solar disk within 65° of disk center, as in our observations, if photospheric field tilts increase during flares as predicted by Hudson et al.

G. J. D. Petrie; J. J. Sudol

2010-01-01T23:59:59.000Z

145

ABRUPT LONGITUDINAL MAGNETIC FIELD CHANGES IN FLARING ACTIVE REGIONS  

SciTech Connect (OSTI)

We characterize the changes in the longitudinal photospheric magnetic field during 38 X-class and 39 M-class flares within 65{sup 0} of disk center using 1 minute GONG magnetograms. In all 77 cases, we identify at least one site in the flaring active region where clear, permanent, stepwise field changes occurred. The median duration of the field changes was about 15 minutes and was approximately equal for X-class and for M-class flares. The absolute values of the field changes ranged from the detection limit of {approx}10 G to as high as {approx}450 G in two exceptional cases. The median value was 69 G. Field changes were significantly stronger for X-class than for M-class flares and for limb flares than for disk-center flares. Longitudinal field changes less than 100 G tended to decrease longitudinal field strengths, both close to disk center and close to the limb, while field changes greater than 100 G showed no such pattern. Likewise, longitudinal flux strengths tended to decrease during flares. Flux changes, particularly net flux changes near disk center, correlated better than local field changes with GOES peak X-ray flux. The strongest longitudinal field and flux changes occurred in flares observed close to the limb. We estimate the change of Lorentz force associated with each flare and find that this is large enough in some cases to power seismic waves. We find that longitudinal field decreases would likely outnumber increases at all parts of the solar disk within 65{sup 0} of disk center, as in our observations, if photospheric field tilts increase during flares as predicted by Hudson et al.

Petrie, G. J. D. [National Solar Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Sudol, J. J. [West Chester University, West Chester, PA 19383 (United States)

2010-12-01T23:59:59.000Z

146

Whistler Modes with Wave Magnetic Fields Exceeding the Ambient Field  

Science Journals Connector (OSTI)

Whistler-mode wave packets with fields exceeding the ambient dc magnetic field have been excited in a large, high electron-beta plasma. The waves are induced with a loop antenna with dipole moment either along or opposite to the dc field. In the latter case the excited wave packets have the topology of a spheromak but are propagating in the whistler mode along and opposite to the dc magnetic field. Field-reversed configurations with net zero helicity have also been produced. The electron magnetohydrodynamics fields are force free, have wave energy density exceeding the particle energy density, and propagate stably at subelectron thermal velocities through a nearly uniform stationary ion density background.

R. L. Stenzel; J. M. Urrutia; K. D. Strohmaier

2006-03-10T23:59:59.000Z

147

Magnetic field stabilization by temperature control of an azimuthally varying field cyclotron magnet  

SciTech Connect (OSTI)

A magnetic field drift, gradual decrease of the order of 10{sup -4} in several tens of hours, was observed with the beam intensity decrease in an operation of an azimuthally varying field (AVF) cyclotron. From our experimental results, we show that the temperature increase of the magnet iron by the heat transfer from the excitation coils can induce such change of the magnetic field as to deteriorate the beam quality. The temperature control of the magnet iron was realized by thermal isolation between the main coil and the yoke and by precise control of the cooling water temperature of the trim coils attached to the pole surfaces in order to prevent temperature change of the magnet iron. The magnetic field stability of {+-}5x10{sup -6} and the beam intensity stability of {+-}2% have been achieved by this temperature control.

Okumura, S.; Arakawa, K.; Fukuda, M.; Nakamura, Y.; Yokota, W.; Ishimoto, T.; Kurashima, S.; Ishibori, I.; Nara, T.; Agematsu, T.; Sano, M.; Tachikawa, T. [Japan Atomic Energy Research Institute (JAERI), 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Sumitomo Heavy Industries, Ltd. (SHI), 5-2 Soubiraki, Niihama, Ehime 792-8588 (Japan)

2005-03-01T23:59:59.000Z

148

http://sunearthday.nasa.gov Exploring Magnetic Field Lines  

E-Print Network [OSTI]

http://sunearthday.nasa.gov Exploring Magnetic Field Lines About this Activity When discussing". Left: Two participants tracing magnetic field lines. Below: Magnetic field line tracings of a bar more field lines. Public Outreach - Make and Take Activities What You'll Need Alnico bar magnets 1

149

Computing nonlinear force free coronal magnetic fields  

E-Print Network [OSTI]

Knowledge of the structure of the coronal magnetic field is important for our understanding of many solar activity phenomena, e.g. flares and CMEs. However, the direct measurement of coronal magnetic fields is not possible with present methods, and therefore the coronal field has to be extrapolated from photospheric measurements. Due to the low plasma beta the coronal magnetic field can usually be assumed to be approximately force free, with electric currents flowing along the magnetic field lines. There are both observational and theoretical reasons which suggest that at least prior to an eruption the coronal magnetic field is in a nonlinear force free state. Unfortunately the computation of nonlinear force free fields is way more difficult than potential or linear force free fields and analytic solutions are not generally available. We discuss several methods which have been proposed to compute nonlinear force free fields and focus particularly on an optimization method which has been suggested recently. We compare the numerical performance of a newly developed numerical code based on the optimization method with the performance of another code based on an MHD relaxation method if both codes are applied to the reconstruction of a semi-analytic nonlinear force-free solution. The optimization method has also been tested for cases where we add random noise to the perfect boundary conditions of the analytic solution, in this way mimicking the more realistic case where the boundary conditions are given by vector magnetogram data. We find that the convergence properties of the optimization method are affected by adding noise to the boundary data and we discuss possibilities to overcome this difficulty.

T. Wiegelmann; T. Neukirch

2008-01-21T23:59:59.000Z

150

Diffusive processes in a stochastic magnetic field  

Science Journals Connector (OSTI)

The statistical representation of a fluctuating (stochastic) magnetic field configuration is studied in detail. The Eulerian correlation functions of the magnetic field are determined, taking into account all geometrical constraints: these objects form a nondiagonal matrix. The Lagrangian correlations, within the reasonable Corrsin approximation, are reduced to a single scalar function, determined by an integral equation. The mean square perpendicular deviation of a geometrical point moving along a perturbed field line is determined by a nonlinear second-order differential equation. The separation of neighboring field lines in a stochastic magnetic field is studied. We find exponentiation lengths of both signs describing, in particular, a decay (on the average) of any initial anisotropy. The vanishing sum of these exponentiation lengths ensures the existence of an invariant which was overlooked in previous works. Next, the separation of a particle’s trajectory from the magnetic field line to which it was initially attached is studied by a similar method. Here too an initial phase of exponential separation appears. Assuming the existence of a final diffusive phase, anomalous diffusion coefficients are found for both weakly and strongly collisional limits. The latter is identical to the well known Rechester-Rosenbluth coefficient, which is obtained here by a more quantitative (though not entirely deductive) treatment than in earlier works.

Hai-Da Wang; M. Vlad; E. Vanden Eijnden; F. Spineanu; J. H. Misguich; R. Balescu

1995-05-01T23:59:59.000Z

151

ThreeThree--dimensional magnetic fielddimensional magnetic field line reconnection involving fluxline reconnection involving flux  

E-Print Network [OSTI]

ThreeThree--dimensional magnetic fielddimensional magnetic field line reconnection involving helicity) · Relaxation of complex field geometries into simpler ones · Magnetic Field Line Reconnection (2D ~ . magnetic field is measured at 20,000 locations #12;Hodogram of central field line in flux tubes

Shyy, Wei

152

Magnetic-field variance in layered superconductors  

Science Journals Connector (OSTI)

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

Ernst Helmut Brandt

1991-06-17T23:59:59.000Z

153

Irregular Magnetic Fields in Interstellar Clouds and Variations in the Observed Circular Polarization of Spectral Lines  

E-Print Network [OSTI]

The strengths of magnetic fields in interstellar gas clouds are obtained through observations of the circular polarization of spectral line radiation. Irregularities in this magnetic field may be present due to turbulence, waves or perhaps other causes, and may play an essential role in the structure and evolution of the gas clouds. To infer information about these irregularities from the observational data, we develop statistical relationships between the rms values of the irregular component of the magnetic field and spatial variations in the circular polarization of the spectral line radiation. The irregularities are characterized in analogy with descriptions of turbulence---by a sum of Fourier waves having a power spectrum with a slope similar to that of Kolmogorov turbulence. For comparison, we also perform computations in which turbulent magnetic and velocity fields from representative MHD simulations by others are utilized. Although the effects of the variations about the mean value of the magnetic field along the path of a ray tend to cancel, a significant residual effect in the polarization of the emergent radiation remains for typical values of the relevant parameters. A map of observed spectra of the 21 cm line toward Orion A is analyzed and the results are compared with our calculations in order to infer the strength of the irregular component of the magnetic field. The rms of the irregular component is found to be comparable in magnitude to the mean magnetic field within the cloud. Hence, the turbulent and Alfven velocities should also be comparable.

W. D. Watson; D. S. Wiebe; R. M. Crutcher

2000-10-13T23:59:59.000Z

154

Sensor for detecting changes in magnetic fields  

DOE Patents [OSTI]

A sensor for detecting changes in the magnetic field of the equilibrium-field coil of a Tokamak plasma device comprises a pair of bifilar wires disposed circumferentially, one inside and one outside the equilibrium-field coil. Each is shorted at one end. The difference between the voltages detected at the other ends of the bifilar wires provides a measure of changing flux in the equilibrium-field coil. This difference can be used to detect faults in the coil in time to take action to protect the coil.

Praeg, Walter F. (Palos Park, IL)

1981-01-01T23:59:59.000Z

155

Sensor for detecting changes in magnetic fields  

DOE Patents [OSTI]

A sensor is described for detecting changes in the magnetic field of the equilibrium-field coil of a Tokamak plasma device that comprises a pair of bifilar wires disposed circumferentially, one inside and one outside the equilibrium-field coil. Each is shorted at one end. The difference between the voltages detected at the other ends of the bifilar wires provides a measure of changing flux in the equilibrium-field coil. This difference can be used to detect faults in the coil in time to take action to protect the coil.

Praeg, W.F.

1980-02-26T23:59:59.000Z

156

THE LARGE-SCALE MAGNETIC FIELDS OF ADVECTION-DOMINATED ACCRETION FLOWS  

SciTech Connect (OSTI)

We calculate the advection/diffusion of the large-scale magnetic field threading an advection-dominated accretion flow (ADAF) and find that the magnetic field can be dragged inward by the accretion flow efficiently if the magnetic Prandtl number P{sub m}={eta}/{nu}{approx}1. This is due to the large radial velocity of the ADAF. It is found that the magnetic pressure can be as high as {approx}50% of the gas pressure in the inner region of the ADAF close to the black hole horizon, even if the external imposed homogeneous vertical field strength is {approx}< 5% of the gas pressure at the outer radius of the ADAF, which is caused by the gas in the ADAF plunging rapidly to the black hole within the marginal stable circular orbit. In the inner region of the ADAF, the accretion flow is significantly pressured in the vertical direction by the magnetic fields, and therefore its gas pressure can be two orders of magnitude higher than that in the ADAF without magnetic fields. This means that the magnetic field strength near the black hole is underestimated by assuming equipartition between magnetic and gas pressure with the conventional ADAF model. Our results show that the magnetic field strength of the flow near the black hole horizon can be more than one order of magnitude higher than that in the ADAF at {approx}3R{sub g} (R{sub g} = 2GM/c{sup 2}), which implies that the Blandford-Znajek mechanism could be more important than the Blandford-Payne mechanism for ADAFs. We find that the accretion flow is decelerated near the black hole by the magnetic field when the external imposed field is strong enough or the gas pressure of the flow is low at the outer radius, or both. This corresponds to a critical accretion rate, below which the accretion flow will be arrested by the magnetic field near the black hole for a given external imposed field. In this case, the gas may accrete as magnetically confined blobs diffusing through field lines in the region very close to the black hole horizon, similar to those in compact stars. Our calculations are also valid for the case that the inner ADAF connects to the outer cold thin disk at a certain radius. In this case, the advection of the external fields is quite inefficient in the outer thin disk due to its low radial velocity, and the field lines thread the disk almost vertically, while these field lines can be efficiently dragged inward by the radial motion of the inner ADAF.

Cao Xinwu, E-mail: cxw@shao.ac.cn [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)

2011-08-20T23:59:59.000Z

157

Coordinate noncommutativity in strong non-uniform magnetic fields  

E-Print Network [OSTI]

Noncommuting spatial coordinates are studied in the context of a charged particle moving in a strong non-uniform magnetic field. We derive a relation involving the commutators of the coordinates, which generalizes the one realized in a strong constant magnetic field. As an application, we discuss the noncommutativity in the magnetic field present in a magnetic mirror.

J. Frenkel; S. H. Pereira

2004-09-23T23:59:59.000Z

158

Determination of the gradient magnetic field above a sunspot based on observations of the HeI and FeI infrared lines  

Science Journals Connector (OSTI)

The magnetic field strength above 36 sunspots was studied using ... 030 nm and FeI 1082.837 nm magnetosensitive lines. The value of the field was determined directly by Zeeman splitting of the lines. The advantag...

L. M. Kozlova; B. V. Somov

2009-10-01T23:59:59.000Z

159

Electro-Mechanical Resonant Magnetic Field Sensor  

E-Print Network [OSTI]

We describe a new type of magnetic field sensor which is termed an Electro-Mechanical Resonant Sensor (EMRS). The key part of this sensor is a small conductive elastic element with low damping rate and therefore a high Q fundamental mode of frequency $f_1$. An AC current is driven through the elastic element which, in the presence of a magnetic field, causes an AC force on the element. When the frequency of the AC current matches the resonant frequency of the element, maximum vibration of the element occurs and this can be measured precisely by optical means. We have built and tested a model sensor of this type using for the elastic element a length of copper wire of diameter 0.030 mm formed into a loop shape. The wire motion was measured using a light emitting diode photo-transistor assembly. This sensor demonstrated a sensitivity better than 0.001G for an applied magnetic field of $ \\sim 1$G and a good selectivity for the magnetic field direction. The sensitivity can be easily improved by a factor of $\\sim ...

Temnykh, A B; Temnykh, Alexander B.; Lovelace, Richard V. E.

2002-01-01T23:59:59.000Z

160

Magnetic Charge and Quantum Field Theory  

Science Journals Connector (OSTI)

A quantum field theory of magnetic and electric charge is constructed. It is verified to be relativistically invariant in consequence of the charge quantization condition eg?c=n, an integer. This is more restrictive than Dirac's condition, which would also allow half-integral values.

Julian Schwinger

1966-04-29T23:59:59.000Z

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


161

National High Magnetic Field Laboratory - Science Starts Here...  

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

correlated electron systems is neutron scattering, often in conjunction with applied magnetic fields. In his own words My experience at the Magnet Lab gave me an early...

162

National High Magnetic Field Laboratory: Museum of Electricity...  

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

navigate the seas, effectively changing the course of history. Related Electricity & Magnetism Pages Museum: Lodestone Timeline: 600 1599 Tutorial: Compasses in Magnetic Fields...

163

High Field Magnet R&D in the USA  

E-Print Network [OSTI]

High Field Magnet R&D in the USA Stephen A. Gourlay magnetLaboratory, Berkeley, CA 94720 USA (telephone: 510-486-7156,

Gourlay, Stephen A.

2003-01-01T23:59:59.000Z

164

Primordial magnetic fields from self-ordering scalar fields  

E-Print Network [OSTI]

A symmetry-breaking phase transition in the early universe could have led to the formation of cosmic defects. Because these defects dynamically excite not only scalar and tensor type cosmological perturbations but also vector type ones, they may serve as a source of primordial magnetic fields. In this study, we calculate the time evolution and the spectrum of magnetic fields that are generated by a type of cosmic defects, called global textures, using the non-linear sigma (NLSM) model. Based on the standard cosmological perturbation theory, we show, both analytically and numerically, that a vector-mode relative velocity between photon and baryon fluids is induced by textures, which inevitably leads to the generation of magnetic fields over a wide range of scales. We find that the amplitude of the magnetic fields is given by $B\\sim{10^{-9}}{((1+z)/10^3)^{-2.5}}({v}/{m_{\\rm pl}})^2({k}/{\\rm Mpc^{-1}})^{3.5}/{\\sqrt{N}}$ Gauss in the radiation dominated era for $k\\lesssim 1$ Mpc$^{-1}$, with $v$ being the vacuum ...

Horiguchi, Kouichirou; Sekiguchi, Toyokazu; Sugiyama, Naoshi

2015-01-01T23:59:59.000Z

165

Circular polarization of obliquely propagating whistler wave magnetic field  

SciTech Connect (OSTI)

The circular polarization of the magnetic field of obliquely propagating whistler waves is derived using a basis set associated with the wave partial differential equation. The wave energy is mainly magnetic and the wave propagation consists of this magnetic energy sloshing back and forth between two orthogonal components of magnetic field in quadrature. The wave electric field energy is small compared to the magnetic field energy.

Bellan, P. M. [Applied Physics, Caltech, Pasadena California 91125 (United States)] [Applied Physics, Caltech, Pasadena California 91125 (United States)

2013-08-15T23:59:59.000Z

166

WD1953-011 - a magnetic white dwarf with peculiar field structure  

E-Print Network [OSTI]

We present H-alpha spectra of the magnetic white dwarf star WD1953-011 which confirm the presence of the broad Zeeman components corresponding to a field strength of about 500kG found by Maxted & Marsh (1999). We also find that the line profile is variable over a timescale of a day or less. The core of the H-alpha line also shows a narrow Zeeman triplet corresponding to a field strength of of about 100kG which appears to be almost constant in shape. These observations suggest that the magnetic field on WD1953-011 has a complex structure and that the star has a rotational period of hours or days which causes the observed variability of the spectra. We argue that neither an offset dipole model nor a double-dipole model are sufficient to explain our observations. Instead, we propose a two component model consisting of a high field region of magnetic field strength of about 500kG covering about 10% of the surface area of the star superimposed on an underlying dipolar field of mean field strength of about 70kG. Radial velocity measurements of the narrow Zeeman triplet show that the radial velocity is constant to within a few km/s so this star is unlikely to be a close binary.

P. F. L. Maxted; L. Ferrario; T. R. Marsh; D. T. Wickramasinghe

2000-05-08T23:59:59.000Z

167

Non-Employee Static Magnetic Field Questionnaire  

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

Occupational Medicine Clinic (OMC) Occupational Medicine Clinic (OMC) Medical Questionnaire for non-BSA Workers/Students who may enter STATIC MAGNETIC FIELDS NAME:_________________ Extension__________ BNL Badge #:_____________ BNL Supervisor_____________ INSTRUCTIONS TO BSA SUPERVISOR or PRECEPTOR: Please print this form and give it to the (non-BSA employee) worker or student for completion. This individual should not give you the completed form, but should instead mail or fax it to OMC. INSTRUCTIONS TO WORKER or STUDENT: The purpose of this questionnaire is to provide the OMC physician at BNL with information about any medical devices or conditions you may have that might affect your ability to safely enter a strong magnetic field, in order to determine whether you can be medically cleared to enter such a field.

168

The ESRF Miniature Pulsed Magnetic Field System  

SciTech Connect (OSTI)

We have developed a portable system to provide pulsed magnetic fields on the ESRF X-ray beamlines. The complete system consists of a power supply, liquid Helium and liquid Nitrogen dewars with a siphon each, control electronics and a double cryostat for separate coil and sample cooling. The liquid nitrogen cooled solenoids reach a maximum field of 30 Tesla for a total pulse duration of one milisecond. They are constructed for optimised cooling rate after the pulse to obtain a high duty cycle, the repetition rate is five pulses per minute at maximum field. The sample is cooled in an independent Helium flow cryostat which is inserted into the bore of the magnet. The flow cryostat has a temperature range from 5 to 250 Kelvin with a direct contact between the sample and Helium flow. This overview gives a general presentation of the system and we will show recent results.

Linden, Peter J. E. M. van der; Strohm, Cornelius; Roth, Thomas; Detlefs, Carsten; Mathon, Olivier [ESRF, 6 rue Jules Horowitz, F-38043 Grenoble (France)

2010-06-23T23:59:59.000Z

169

Magnetic field exposure among utility workers  

SciTech Connect (OSTI)

The Electric and Magnetic Field Measurement Project for Utilities -- the Electric Power Research Institute (EPRI) Electric and Magnetic Field Digital Exposure (EMDEX) Project (the EPRI EMDEX Project) -- was a multifaceted project that entailed technology transfer, measurement protocol design, data management, and exposure assessment analyses. This paper addresses one specific objective of the project: the collection, analysis, and documentation of power-frequency magnetic filed exposures for a diverse population of utility employees at 59 sites in four countries between September, 1988, and September, 1989. Specially designed sampling procedures and data collection protocols were used to ensure uniform implementation across sites. Volunteers within 13 job classifications recorded which of eight work or three nonwork environments they occupied while wearing an EMDEX meter. Approximately 50,000 hours of magnetic field exposure records taken at 10 s intervals were obtained, about 70% of which were from work environments. Exposures and time spent in environments were analyzed by primary work environment, by occupied environment, and by job classification.

Bracken, T.D.; Senior, R.S. [T. Dan Bracken, Inc., Portland, OR (United States); Rankin, R.F. [Applied Research Services, Inc., Lake Oswego, OR (United States); Alldredge, J.R. [Washington State Univ., Pullman, WA (United States); Sussman, S.S. [Electric Power Research Institute, Palo Alto, CA (United States)

1995-09-01T23:59:59.000Z

170

Solar axions as an energy source and modulator of the Earth magnetic field  

E-Print Network [OSTI]

We show existence of strong negative correlation between the temporal variations of magnetic field toroidal component of the solar tachocline (the bottom of convective zone) and the Earth magnetic field (Y-component). The possibility that hypothetical solar axions, which can transform into photons in external electric or magnetic fields (the inverse Primakoff effect), can be the instrument by which the magnetic field of convective zone of the Sun modulates the magnetic field of the Earth is considered. We propose the axion mechanism of "solar dynamo-geodynamo" connection, where an energy of axions, which form in the Sun core, is modulated at first by the magnetic field of the solar tachocline zone (due to the inverse coherent Primakoff effect) and after that is absorbed in the liquid core of the Earth under influence of the terrestrial magnetic field, thereby playing the role of an energy source and a modulator of the Earth magnetic field. Within the framework of this mechanism new estimations of the strength of an axion coupling to a photon (ga_gamma about 5*10^-9 GeV^-1) and the axion mass (ma ~ 30 eV) have been obtained.

V. D. Rusov; E. P. Linnik; K. Kudela; S. Cht. Mavrodiev; T. N. Zelentsova; V. P. Smolyar; K. K. Merkotan

2010-08-16T23:59:59.000Z

171

EXPLORING MAGNETIC FIELD STRUCTURE IN STAR-FORMING CORES WITH POLARIZATION OF THERMAL DUST EMISSION  

SciTech Connect (OSTI)

The configuration and evolution of the magnetic field in star-forming cores are investigated in order to directly compare simulations and observations. We prepare four different initial clouds having different magnetic field strengths and rotation rates, in which magnetic field lines are aligned/misaligned with the rotation axis. First, we calculate the evolution of such clouds from the prestellar stage until long after protostar formation. Then, we calculate the polarization of thermal dust emission expected from the simulation data. We create polarization maps with arbitrary viewing angles and compare them with observations. Using this procedure, we confirmed that the polarization distribution projected on the celestial plane strongly depends on the viewing angle of the cloud. Thus, by comparing the observations with the polarization map predicted by the simulations, we can roughly determine the angle between the direction of the global magnetic field and the line of sight. The configuration of the polarization vectors also depends on the viewing angle. We find that an hourglass configuration of magnetic field lines is not always realized in a collapsing cloud when the global magnetic field is misaligned with the cloud rotation axis. Depending on the viewing angle, an S-shaped configuration of the magnetic field (or the polarization vectors) appears early in the protostellar accretion phase. This indicates that not only the magnetic field but also the cloud rotation affects the dynamical evolution of such a cloud. In addition, by comparing the simulated polarization with actual observations, we can estimate properties of the host cloud such as the evolutionary stage, magnetic field strength, and rotation rate.

Kataoka, Akimasa [Department of Astronomy, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Machida, Masahiro N. [Department of Earth and Planetary Science, Kyushu University, Higashi-ku, Fukuoka 812-8581 (Japan); Tomisaka, Kohji [Department of Astronomical Science, School of Physical Sciences, Graduate University for Advanced Studies (SOKENDAI), Osawa 2-21-1, Mitaka, Tokyo 181-8588 (Japan)

2012-12-10T23:59:59.000Z

172

Destruction of invariant surfaces and magnetic coordinates for perturbed magnetic fields  

E-Print Network [OSTI]

of Physics. DOI: 10.1063/1.1640379 I. INTRODUCTION As toroidal magnetic field line flow, with non be constructed everywhere.5 The analog of action-angle co- ordinates for magnetic field line flow is straight-field-line, all the magnetic field lines lie on flux surfaces. For a non-integrable field the situ- ation is more

Hudson, Stuart

173

The measurement and analysis of the magnetic field of a synchrotron light source magnet  

E-Print Network [OSTI]

In this thesis a unique system is used to measure the magnetic field of a superconducting synchrotron light source magnet. The magnet measured is a superferric dipole C-magnet designed to produce a magnetic field up to 3 Tesla in magnitude. Its...

Graf, Udo Werner

2012-06-07T23:59:59.000Z

174

Magnetic susceptibility and magnetization properties of asymmetric nuclear matter under a strong magnetic field  

E-Print Network [OSTI]

We study the effect of a strong magnetic field on the proton and neutron spin polarization and magnetic susceptibility of asymmetric nuclear matter within a relativistic mean-field approach. It is shown that magnetic fields $B \\sim 10^{16} - 10^{17}$ G have already noticeable effects on the range of densities of interest for the study of the crust of a neutron star. Although the proton susceptibility is larger for weaker fields, the neutron susceptibility becomes of the same order or even larger for small proton fractions and subsaturation densities for $B > 10^{16}$ G. We expect that neutron superfluidity in the crust will be affected by the presence of magnetic fields.

A. Rabhi; M. A. Pérez-García; C. Providência; I. Vidaña

2014-10-10T23:59:59.000Z

175

22Mathematical Model of Magnetic Field Lines -II Magnets have a north and a south  

E-Print Network [OSTI]

22Mathematical Model of Magnetic Field Lines - II Magnets have a north and a south pole. If you and 4 to complete the magnetic field line drawing! Space Math http://spacemath.gsfc.nasa.gov #12 diagram in the First Quadrant into quadrants 2, 3 and 4 to complete the magnetic field line drawing

176

Control of stochasticity in magnetic field lines  

E-Print Network [OSTI]

We present a method of control which is able to create barriers to magnetic field line diffusion by a small modification of the magnetic perturbation. This method of control is based on a localized control of chaos in Hamiltonian systems. The aim is to modify the perturbation locally by a small control term which creates invariant tori acting as barriers to diffusion for Hamiltonian systems with two degrees of freedom. The location of the invariant torus is enforced in the vicinity of the chosen target. Given the importance of confinement in magnetic fusion devices, the method is applied to two examples with a loss of magnetic confinement. In the case of locked tearing modes, an invariant torus can be restored that aims at showing the current quench and therefore the generation of runaway electrons. In the second case, the method is applied to the control of stochastic boundaries allowing one to define a transport barrier within the stochastic boundary and therefore to monitor the volume of closed field lines.

Cristel Chandre; Michel Vittot; Guido Ciraolo; Philippe Ghendrih; Ricardo Lima

2005-04-14T23:59:59.000Z

177

Solar magnetic fields and terrestrial climate  

E-Print Network [OSTI]

Solar irradiance is considered one of the main natural factors affecting terrestrial climate, and its variations are included in most numerical models estimating the effects of natural versus anthropogenic factors for climate change. Solar wind causing geomagnetic disturbances is another solar activity agent whose role in climate change is not yet fully estimated but is a subject of intense research. For the purposes of climate modeling, it is essential to evaluate both the past and the future variations of solar irradiance and geomagnetic activity which are ultimately due to the variations of solar magnetic fields. Direct measurements of solar magnetic fields are available for a limited period, but can be reconstructed from geomagnetic activity records. Here we present a reconstruction of total solar irradiance based on geomagnetic data, and a forecast of the future irradiance and geomagnetic activity relevant for the expected climate change.

Georgieva, Katya; Kirov, Boian

2014-01-01T23:59:59.000Z

178

Coulomb gaps in a strong magnetic field  

Science Journals Connector (OSTI)

We report on a study of interaction effects in the tunneling density of states of a disordered two-dimensional electron gas in the strong magnetic field limit where only the lowest Landau level is occupied. Interactions in the presence of disorder are accounted for by performing finite-size self-consistent Hartree-Fock calculations. We find evidence for the formation of a pseudogap with a tunneling density of states which vanishes at the Fermi energy.

S.-R. Eric Yang and A. H. MacDonald

1993-06-28T23:59:59.000Z

179

Response of plastic scintillators in magnetic fields  

SciTech Connect (OSTI)

The dependence of the light yield on magnetic field has been measured up to 0.45 T for the plastic scintillators NE-102A, SCSN-38 and Polivar. The scintillators were excited by 25 MeV protons, 5.9 keV X-rays and UV light. When excited with ionizing radiation an increase of light yield is observed. For SCSN-38 of 2.7 mm thickness it amounts to 0.3%, 0.9%, 1.1% and 3.3% at 1, 10, 100 and 450 mT respectively. NE-102A behaves similar, whereas a PMMA based scintillator shows a stronger field dependence.

Blomker, D.; Holm, V. (Inst. Experimentalphysik, Universitat Hamburg, Luruper Chaussee 149, D-2000 Hamburg 50 (DE)); Klanner, R.; Krebs, B. (Deutsches Elektronen-Synchroton, Notkstr. 85, D-2000 Hamburg 52 (DE))

1990-04-01T23:59:59.000Z

180

The Search for a Primordial Magnetic Field  

E-Print Network [OSTI]

Magnetic fields appear wherever plasma and currents can be found. As such, they thread through all scales in Nature. It is natural, therefore, to suppose that magnetic fields might have been formed within the high temperature environments of the big bang. Such a primordial magnetic field (PMF) would be expected to arise from and/or influence a variety of cosmological phenomena such as inflation, cosmic phase transitions, big bang nucleosynthesis, the cosmic microwave background (CMB) temperature and polarization anisotropies, the cosmic gravity wave background, and the formation of large-scale structure. In this review, we summarize the development of theoretical models for analyzing the observational consequences of a PMF. We also summarize the current state of the art in the search for observational evidence of a PMF. In particular we review the framework needed to calculate the effects of a PMF power spectrum on the CMB and the development of large scale structure. We summarize the current constraints on the PMF amplitude $B_\\lambda$ and the power spectral index $n_B$ and discuss prospects for better determining these quantities in the near future.

Dai G. Yamazaki; Toshitaka Kajino; Grant J. Mathew; Kiyotomo Ichiki

2012-04-16T23:59:59.000Z

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


181

Improved Magnetic Field Generation Efficiency and Higher Temperature Spheromak Plasmas  

SciTech Connect (OSTI)

New understanding of the mechanisms governing the observed magnetic field generation limits on the sustained spheromak physics experiment has been obtained. Extending the duration of magnetic helicity injection during the formation of a spheromak and optimizing the ratio of injected current to bias flux produce higher magnetic field plasmas with record spheromak electron temperatures. To explore magnetic field buildup efficiency limits, the confinement region geometry was varied resulting in improved field buildup efficiencies.

Wood, R D; Hill, D N; McLean, H S; Hooper, E B; Hudson, B F; Moller, J M; Romero-Talamas, C A

2008-09-15T23:59:59.000Z

182

Improved magnetic field generation efficiency and higher temperature spheromak plasmas  

Science Journals Connector (OSTI)

New understanding of the mechanisms governing the observed magnetic field generation limits on the sustained spheromak physics experiment has been obtained. Extending the duration of magnetic helicity injection during the formation of a spheromak and optimizing the ratio of injected current to bias flux produce higher magnetic field plasmas with record spheromak electron temperatures. To explore magnetic field buildup efficiency limits, the confinement region geometry was varied resulting in improved field buildup efficiencies.

R.D. Wood; D.N. Hill; H.S. McLean; E.B. Hooper; B.F. Hudson; J.M. Moller; C.A. Romero-Talamás

2009-01-01T23:59:59.000Z

183

ECE 390 Electric & Magnetic Fields Catalog Description: Static and quasi-static electric and magnetic fields.  

E-Print Network [OSTI]

ECE 390 ­ Electric & Magnetic Fields Catalog Description: Static and quasi-static electric), A. Jander (secondary) Course Content: · Introduction, review of vector analysis · Static electric fields in free space: Coulomb's law, Gauss's law, and electric potential, electric dipole · Static

184

National High Magnetic Field Laboratory - Science Starts Here...  

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

a better and much more productive scientist. I had the opportunity to learn unique high magnetic field experimental techniques from the top researchers in the field, in a...

185

Magnetic Field based Heading Estimation for Pedestrian Navigation Environments  

E-Print Network [OSTI]

Magnetic Field based Heading Estimation for Pedestrian Navigation Environments Muhammad Haris Afzal held devices, these other sources are accelerometers for roll and pitch estimates and magnetic field sensors for the heading. In order to utilize the magnetic field sensors for heading estimation

Calgary, University of

186

2.6 ELECTRIC AND MAGNETIC FIELDS Introduction  

E-Print Network [OSTI]

325 §2.6 ELECTRIC AND MAGNETIC FIELDS Introduction In electromagnetic theory the mks system MKS units Replacement symbol GAUSSIAN units E (Electric field) volt/m E statvolt/cm B (Magnetic field gauss-cm V (Electric potential) volt V statvolt (Dielectric constant) 4 µ (Magnetic permeability) 4µ c2

California at Santa Cruz, University of

187

Studies of Avalanche Photodiode Performance in a High Magnetic Field  

E-Print Network [OSTI]

We report the results of exposing a Hamamatsu avalanche photodiode (APD) to a 7.9 Tesla magnetic field. The effect of the magnetic field on the gain of the APD is shown and discussed. We find APD gain to be unaffected in the presence of such a magnetic field.

J. Marler; T. McCauley; S. Reucroft; J. Swain; D. Budil; S. Kolaczkowski

2000-01-04T23:59:59.000Z

188

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

Science Journals Connector (OSTI)

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

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

1998-01-01T23:59:59.000Z

189

Two-colour QCD at non-zero temperature in the presence of a strong magnetic field  

E-Print Network [OSTI]

In this talk we report on our study of two-colour lattice QCD with N_f=4 staggered fermion degrees of freedom with equal electric charge q in a homogeneous magnetic field B at non-zero temperature T. We find indications for a non-monotonic behaviour of the critical temperature as a function of the magnetic field strength and, as a consequence, for the occurence of `inverse magnetic catalysis' within the transition region for magnetic fields in the range 0 < qB < 0.7 GeV^2.

M. Muller-Preussker; B. Petersson; A. Schreiber; E. -M. Ilgenfritz; M. Kalinowski

2014-02-01T23:59:59.000Z

190

Interaction of magnetic resonators studied by the magnetic field enhancement  

SciTech Connect (OSTI)

It is the first time that the magnetic field enhancement (MFE) is used to study the interaction of magnetic resonators (MRs), which is more sensitive than previous parameters–shift and damping of resonance frequency. To avoid the coherence of lattice and the effect of Bloch wave, the interaction is simulated between two MRs with same primary phase when the distance is changed in the range of several resonance wavelengths, which is also compared with periodic structure. The calculated MFE oscillating and decaying with distance with the period equal to resonance wavelength directly shows the retardation effect. Simulation also shows that the interaction at normal incidence is sensitive to the phase correlation which is related with retardation effect and is ultra-long-distance interaction when the two MRs are strongly localized. When the distance is very short, the amplitude of magnetic resonance is oppressed by the strong interaction and thus the MFE can be much lower than that of single MR. This study provides the design rules of metamaterials for engineering resonant properties of MRs.

Hou, Yumin, E-mail: ymhou@pku.edu.cn [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China)] [State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China)

2013-12-15T23:59:59.000Z

191

How to use magnetic field information for coronal loop identification?  

E-Print Network [OSTI]

The structure of the solar corona is dominated by the magnetic field because the magnetic pressure is about four orders of magnitude higher than the plasma pressure. Due to the high conductivity the emitting coronal plasma (visible e.g. in SOHO/EIT) outlines the magnetic field lines. The gradient of the emitting plasma structures is significantly lower parallel to the magnetic field lines than in the perpendicular direction. Consequently information regarding the coronal magnetic field can be used for the interpretation of coronal plasma structures. We extrapolate the coronal magnetic field from photospheric magnetic field measurements into the corona. The extrapolation method depends on assumptions regarding coronal currents, e.g. potential fields (current free) or force-free fields (current parallel to magnetic field). As a next step we project the reconstructed 3D magnetic field lines on an EIT-image and compare with the emitting plasma structures. Coronal loops are identified as closed magnetic field lines with a high emissivity in EIT and a small gradient of the emissivity along the magnetic field.

T. Wiegelmann; B. Inhester; A. Lagg; S. K. Solanki

2008-01-30T23:59:59.000Z

192

Mapping Magnetic Near-Field Distributions of Plasmonic Nanoantennas  

Science Journals Connector (OSTI)

However, standard far-field optical microscopy methods have insufficient resolution and provide no information about the electromagnetic near-fields. ... The top right panel of Figure 3a illustrates how the charges and magnetic near-field (green circles) at the probe aperture line up with the charge distribution and magnetic near-field of the SPR mode. ... and magnetic field lines and Poynting vector distributions are reconstructed in a vol. ...

Denitza Denkova; Niels Verellen; Alejandro V. Silhanek; Ventsislav K. Valev; Pol Van Dorpe; Victor V. Moshchalkov

2013-03-06T23:59:59.000Z

193

Magnetic fields at the periphery of UCHII regions from carbon recombination line observations  

E-Print Network [OSTI]

Several indirect evidences indicate a magnetic origin for the non-thermal width of spectral lines observed toward molecular clouds. In this letter, I suggest that the origin of the non-thermal width of carbon recombination lines (CRLs) observed from photo-dissociation regions (PDRs) near ultra-compact \\HII\\ regions is magnetic and that the magnitude of the line width is an estimate of the \\alfven speed. The magnetic field strengths estimated based on this suggestion compare well with those measured toward molecular clouds with densities similar to PDR densities. I conclude that multi-frequency CRL observations have the potential to form a new tool to determine the field strength near star forming regions.

D. Anish Roshi

2007-02-06T23:59:59.000Z

194

Photon Magnetic Moment and Vacuum Magnetization in an Asymptotically Large Magnetic Field  

E-Print Network [OSTI]

We consider the effect of the photon radiative correction on the vacuum energy in a superstrong magnetic field. The notion of a photon anomalous magnetic moment is analyzed and its connection with the quasiparticle character of the electromagnetic radiation is established. In the infrared domain the magnetic moment turns out to be a vector with two orthogonal components in correspondence with the cylindrical symmetry imposed by the external field. The possibility of defining such quantity in the high energy limit is studied as well. Its existence suggests that the electromagnetic radiation is a source of magnetization to the whole vacuum and thus its electron-positron zero-point energy is slightly modified. The corresponding contribution to the vacuum magnetization density is determined by considering the individual contribution of each vacuum polarization eigenmode in the Euler-Heisenberg Lagrangian. A paramagnetic response is found in one of them, whereas the remaining ones are diamagnetic. Additional issues concerning the transverse pressures are analyzed.

Selym Villalba Chavez

2009-10-27T23:59:59.000Z

195

Combined Effects of Unsteady Electric Field and Uniform Magnetic Field on Magnetoelectroconvection in a Poorly Conducting Plasma  

Science Journals Connector (OSTI)

The magnetoelectroconvective instability of a plane horizontal layer of a poorly conducting plasma subjected to a strong nonuniform electric field and uniform magnetic field is investigated in the combined magnetoelectrohydrodynamic approximations when charge formation is produced by this convection. The spatio?temporal variation of electric field density of charge distribution and temperature are found for the quiescent basic state. The influence of combined uniform magnetic field and a time?dependent electric field modulation on the behaviour of a poorly conducting plasma is studied using energy and moment methods along with Galerkin technique. The criterion for the onset of magnetoelectroconvection involving the effects of both strong electric and magnetic fields is computed and the results are compared with these obtained only in the presence of electric field. We found that the combined effect of electric and magnetic fields is more favourable to suppress convection significantly than in the presence of electric field alone. This result is useful in synthesizing smart and strong materials needed for many aeronautical automobile and biomedical engineering applications to minimize the weight and maximize the strength to achieve the sufficient dynamic advantages.

M. S. Gayathri

2006-01-01T23:59:59.000Z

196

Graphene transparency in weak magnetic fields  

E-Print Network [OSTI]

We carry out an explicit calculation of the vacuum polarization tensor for an effective low-energy model of monolayer graphene in the presence of a weak magnetic field of intensity $B$ perpendicularly aligned to the membrane. By expanding the quasiparticle propagator in the Schwinger proper time representation up to order $(eB)^2$, where $e$ is the unit charge, we find an explicitly transverse tensor, consistent with gauge invariance. Furthermore, assuming that graphene is radiated with monochromatic light of frequency $\\omega$ along the external field direction, from the modified Maxwell's equations we derive the intensity of transmitted light and the angle of polarization rotation in terms of the longitudinal ($\\sigma_{xx}$) and transverse ($\\sigma_{xy}$) conductivities. Corrections to these quantities, both calculated and measured, are of order $(eB)^2/\\omega^4$. Our findings generalize and complement previously known results reported in literature regarding the light absorption problem in graphene from the experimental and theoretical points of view, with and without external magnetic fields.

David Valenzuela; Saúl Hernández-Ortiz; Marcelo Loewe; Alfredo Raya

2014-10-20T23:59:59.000Z

197

Rotating-frame gradient fields for magnetic resonance imaging and nuclear magnetic resonance in low fields  

DOE Patents [OSTI]

A system and method for Fourier encoding a nuclear magnetic resonance (NMR) signal is disclosed. A static magnetic field B.sub.0 is provided along a first direction. An NMR signal from the sample is Fourier encoded by applying a rotating-frame gradient field B.sub.G superimposed on the B.sub.0, where the B.sub.G comprises a vector component rotating in a plane perpendicular to the first direction at an angular frequency .omega.in a laboratory frame. The Fourier-encoded NMR signal is detected.

Bouchard, Louis-Serge; Pines, Alexander; Demas, Vasiliki

2014-01-21T23:59:59.000Z

198

Maintaining the closed magnetic-field-line topology of a field-reversed configuration (FRC)  

E-Print Network [OSTI]

1 Maintaining the closed magnetic-field-line topology of a field-reversed configuration (FRC, WA 98052 Abstract The effects on magnetic-field-line structure of adding various static transverse introduce pronounced shear. #12;2 I. Introduction Magnetic field lines are closed. Where closure occurs

199

Vacuum birefringence in strong magnetic fields: (II) Complex refractive index from the lowest Landau level  

SciTech Connect (OSTI)

We compute the refractive indices of a photon propagating in strong magnetic fields on the basis of the analytic representation of the vacuum polarization tensor obtained in our previous paper. When the external magnetic field is strong enough for the fermion one-loop diagram of the polarization tensor to be approximated by the lowest Landau level, the propagating mode in parallel to the magnetic field is subject to modification: The refractive index deviates from unity and can be very large, and when the photon energy is large enough, the refractive index acquires an imaginary part indicating decay of a photon into a fermion–antifermion pair. We study dependences of the refractive index on the propagating angle and the magnetic-field strength. It is also emphasized that a self-consistent treatment of the equation which defines the refractive index is indispensable for accurate description of the refractive index. This self-consistent treatment physically corresponds to consistently including the effects of back reactions of the distorted Dirac sea in response to the incident photon. -- Highlights: •Vacuum birefringence and photon decay are described by the complex refractive index. •Resummed photon vacuum polarization tensor in the lowest Landau level is used. •Back reactions from the distorted Dirac sea are self-consistently taken into account. •Self-consistent treatment drastically changes structure in photon energy dependence. •Dependences on photon propagation angle and magnetic-field strength are presented.

Hattori, Koichi, E-mail: khattori@yonsei.ac.kr [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of)] [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Itakura, Kazunori, E-mail: kazunori.itakura@kek.jp [Theory Center, IPNS, High energy accelerator research organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan) [Theory Center, IPNS, High energy accelerator research organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Department of Particle and Nuclear Studies, Graduate University for Advanced Studies (SOKENDAI), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

2013-07-15T23:59:59.000Z

200

Exploring Ultrahigh Magnetic Field Processing of Materials for Developing Customized Microstructures and Enhanced Performance  

SciTech Connect (OSTI)

Thermodynamic calculations based on Gibbs free energy in the magnetization-magnetic intensity-temperature (M-H-T) magnetic equation of state space demonstrate that significantly different phase equilibria may result for those material systems where the product and parent phases exhibit different magnetization responses. These calculations show that the Gibbs free energy is changed by a factor equal to -MdH, where M and H are the magnetization and applied field strength, respectively. Magnetic field processing is directly applicable to a multitude of alloys and compounds for dramatically influencing phase stability and phase transformations. This ability to selectively control microstructural stability and alter transformation kinetics through appropriate selection of the magnetic field strength promises to provide a very robust mechanism for developing and tailoring enhanced microstructures (and even nanostructures through accelerated kinetics) with superior properties for a broad spectrum of material applications. For this Industrial Materials for the Future (IMF) Advanced Materials for the Future project, ferrous alloys were studied initially since this alloy family exhibits ferromagnetism over part of its temperature range of stability and therefore would demonstrate the maximum impact of this novel processing mechanism. Additionally, with these ferrous alloys, the high-temperature parent phase, austenite, exhibits a significantly different magnetization response from the potential product phases, ferrite plus carbide or martensite; and therefore, the solid-state transformation behavior of these alloys will be dramatically influenced by the presence of ultrahigh magnetic fields. Finally, a thermodynamic calculation capability (within ThermoCalc for example) was developed during this project to enable parametric studies to be performed to predict the magnitude of the influence of magnetic processing variables on the phase stability (phase diagrams) in ferromagnetic materials of relevance to the Industries of the Future (IOF).

Ludtka, GERALD M.

2005-03-31T23:59:59.000Z

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


201

Polarized neutron reflectometry in high magnetic fields  

SciTech Connect (OSTI)

A simple method is described to maintain the polarization of a neutron beam on its way through the large magnetic stray fields produced by a vertical field of a cryomagnet with a split-coil geometry. The two key issues are the proper shielding of the neutron spin flippers and an additional radial field component in order to guide the neutron spin through the region of the null point (i.e., point of reversal for the vertical field component). Calculations of the neutron's spin rotation as well as polarized neutron reflectometry experiments on an ErFe{sub 2}/DyFe{sub 2} multilayer show the perfect performance of the used setup. The recently commissioned cryomagnet M5 with a maximum vertical field of up to 7.2 T in asymmetric mode for polarized neutrons and 9 T in symmetric mode for unpolarized neutrons was used on the C5 spectrometer in reflectometry mode, at the NRU reactor in Chalk River, Canada.

Fritzsche, H. [National Research Council Canada, Canadian Neutron Beam Centre, Chalk River Laboratories, Chalk River, Ontario K0J 1J0 (Canada)

2005-11-15T23:59:59.000Z

202

Magnetic Fields in the Formation of Sun-Like Stars  

E-Print Network [OSTI]

We report high-angular-resolution measurements of polarized dust emission toward the low-mass protostellar system NGC 1333 IRAS 4A. We show that in this system the observed magnetic field morphology is in agreement with the standard theoretical models of the formation of Sun-like stars in magnetized molecular clouds at scales of a few hundred astronomical units; gravity has overcome magnetic support, and the magnetic field traces a clear hourglass shape. The magnetic field is substantially more important than turbulence in the evolution of the system, and the initial misalignment of the magnetic and spin axes may have been important in the formation of the binary system.

Josep M. Girart; Ramprasad Rao; Daniel P. Marrone

2006-09-06T23:59:59.000Z

203

Graphene transparency in weak magnetic fields  

E-Print Network [OSTI]

We carry out an explicit calculation of the vacuum polarization tensor for an effective low-energy model of monolayer graphene in the presence of a weak magnetic field of intensity $B$ perpendicularly aligned to the membrane. By expanding the quasiparticle propagator in the Schwinger proper time representation up to order $(eB)^2$, where $e$ is the unit charge, we find an explicitly transverse tensor, consistent with gauge invariance. Furthermore, assuming that graphene is radiated with monochromatic light of frequency $\\omega$ along the external field direction, from the modified Maxwell's equations we derive the intensity of transmitted light and the angle of polarization rotation in terms of the longitudinal ($\\sigma_{xx}$) and transverse ($\\sigma_{xy}$) conductivities. Corrections to these quantities, both calculated and measured, are of order $(eB)^2/\\omega^4$. Our findings generalize and complement previously known results reported in literature regarding the light absorption problem in graphene from th...

Valenzuela, David; Loewe, Marcelo; Raya, Alfredo

2014-01-01T23:59:59.000Z

204

Optical pumping magnetic resonance in high magnetic fields: Characterization of nuclear relaxation during pumping  

E-Print Network [OSTI]

Optical pumping magnetic resonance in high magnetic fields: Characterization of nuclear relaxation during pumping Matthew P. Augustine and Kurt W. Zilm Department of Chemistry, Yale University, New Haven exchange with optically pumped Rb vapor is investigated in high magnetic field. Operation in a high field

Augustine, Mathew P.

205

Motion of charged particles in ABC magnetic fields Alejandro Luque #  

E-Print Network [OSTI]

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

206

The Generation of Nonaxisymmetric Magnetic Fields in the Giant Planets  

E-Print Network [OSTI]

by the National Science Foundation 1 #12; INTRODUCTION The dipole moments of the magnetic fields of JupiterThe Generation of Nonaxisymmetric Magnetic Fields in the Giant Planets David Moss Mathematics shells, with anisotropic alpha and magnetic diffusivity tensors which are functions of the inverse Rossby

Brandenburg, Axel

207

Sidewall containment of liquid metal with horizontal alternating magnetic fields  

DOE Patents [OSTI]

An apparatus is disclosed for confining molten metal with a horizontal alternating magnetic field. In particular, this invention employs a magnet that can produce a horizontal alternating magnetic field to confine a molten metal at the edges of parallel horizontal rollers as a solid metal sheet is cast by counter-rotation of the rollers. 19 figs.

Praeg, W.F.

1995-01-31T23:59:59.000Z

208

Efficient solar anti-neutrino production in random magnetic fields  

E-Print Network [OSTI]

We have shown that the electron anti-neutrino appearance in the framework of the spin flavor conversion mechanism is much more efficient in the case of neutrino propagation through random than regular magnetic field. This result leads to much stronger limits on the product of the neutrino transition magnetic moment and the solar magnetic field based on the recent KamLAND data. We argue that the existence of the random magnetic fields in the solar convective zone is a natural sequence of the convective zone magnetic field evolution.

O. G. Miranda; T. I. Rashba; A. I. Rez; J. W. F. Valle

2004-05-12T23:59:59.000Z

209

Variable magnetic field geometry of the young sun HN Peg (HD 206860)  

E-Print Network [OSTI]

The large-scale magnetic field of solar-type stars reconstructed from their spectropolarimetric observations provide important insight into their underlying dynamo processes.We aim to investigate the temporal variability of the large-scale surface magnetic field and chromospheric activity of a young solar analogue, the G0 dwarf HN Peg.The large-scale surface magnetic field topology is reconstructed using Zeeman Doppler Imaging at six observational epochs covering seven years.We also investigated the chromospheric activity variations by measuring the flux in the line cores of the three chromospheric activity indicators: Ca II H&K, H alpha, and the Ca II IRT lines.The magnetic topology of HN Peg shows a complex and variable geometry. While the radial field exhibits a stable positive polarity magnetic region at the poles at each observational epoch, the azimuthal field is strongly variable in strength, where a strong band of positive polarity magnetic field is present at equatorial latitudes. This field disa...

Saikia, S Boro; Petit, P; Marsden, S; Morin, J; Folsom, C P

2014-01-01T23:59:59.000Z

210

Goos-Hänchen like Shifts for Graphene Barrier in Constant Magnetic Field  

E-Print Network [OSTI]

We consider a system of Dirac fermions in graphene submitted to a constant perpendicular magnetic field and scattered by a barrier potential. We show that our system can be used to establish a link with quantum optics through the Goos-H\\"{a}nchen shifts. This can be done by evaluating the corresponding transmission probability and shift phase. We obtain Goos-H\\"{a}nchen like shifts in terms of different physical parameters such as energy, electrostatic potential strength and magnetic field. On the light of this relation, we discuss the obtained results and make comparison with literature.

Ahmed Jellal; Miloud Mekkaoui; Youness Zahidi

2014-04-17T23:59:59.000Z

211

Average East-West Inclinations of Surface Magnetic Field Lines  

Science Journals Connector (OSTI)

The east-west component of the inclination to the vertical of magnetic field lines of fields measured at the photospheric level is calculated ... and as a function of latitude. These fields represent mostly non-s...

Robert F. Howard

1994-01-01T23:59:59.000Z

212

Density-Functional-Theory Calculations of Matter in Strong Magnetic Fields: I. Atoms and Molecules  

E-Print Network [OSTI]

We present new ab initio calculations of the electronic structure of various atoms and molecules in strong magnetic fields ranging from B=10^12 G to 2x10^15 G, appropriate for radio pulsars and magnetars. For these field strengths, the magnetic forces on the electrons dominate over the Coulomb forces, and to a good approximation the electrons are confined to the ground Landau level. Our calculations are based on the density functional theory, and use a local magnetic exchange-correlation function which is tested to be reliable in the strong field regime. Numerical results of the ground-state energies are given for H_N (up to N=10), He_N (up to N=8), C_N (up to N=5) and Fe_N (up to N=3), as well as for various ionized atoms. Fitting formulae for the B-dependence of the energies are also given. In general, as N increases, the binding energy per atom in a molecule, |E_N|/N, increases and approaches a constant value. For all the field strengths considered in this paper, hydrogen, helium, and carbon molecules are found to be bound relative to individual atoms (although for B less than a few x 10^12 G, the relative binding between C and C_2 is small). Iron molecules are not bound at B<10^13 G, but become energetically more favorable than individual atoms at larger field strengths.

Zach Medin; Dong Lai

2007-01-05T23:59:59.000Z

213

Propagation of MHD waves in a plasma in a sheared magnetic field with straight field lines  

Science Journals Connector (OSTI)

The propagation of MHD plasma waves in a sheared magnetic field is investigated. The problem is solved using ... is inhomogeneous in one direction, and the magnetic field lines are straight. The waves are assumed...

P. N. Mager; D. Yu. Klimushkin

2002-04-01T23:59:59.000Z

214

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

SciTech Connect (OSTI)

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

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

2012-02-01T23:59:59.000Z

215

MagLab - MagLab Dictionary: Magnetic Field (Transcript)  

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

stronger magnetic field, it has even stronger effects. It can hold things to your refrigerator or, in the case of our magnets, can greatly affect how electrons move inside of...

216

Transport of Paramagnetic Liquids under Nonuniform High Magnetic Field  

Science Journals Connector (OSTI)

The recent development of numerous superconducting magnets led to remarkable increment of the investigations under high magnetic field intensities in particular in chemistry, physics and biology.1 The application of high magnetic fields clarified the existence of the magnetic force acting on any kind of nonmagnetic (paramagnetic or diamagnetic) materials. ... In the experimental conditions where the bore axis of the superconducting magnet is set vertically, the magnetic field takes a parabolic distribution in a horizontal direction with rotational symmetry, such as where B0 is the magnetic flux density in the center of the bore, ? the coefficient characterizing the parabolic shape of the magnetic field distribution, and r the coordinate of the radial axis. ... T. Dashed lines are fitted curves from eq 17. ...

Olivier Devos; Ryoichi Aogaki

2000-05-10T23:59:59.000Z

217

National High Magnetic Field Laboratory Slideshow: Making an...  

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

Create your own magnetic field lines, expose the iron in your cereal, or make an electromagnet from scratch Your teachers or parents may even want to get in on the fun. Magnets...

218

Gregory S. Boebinger, National High Magnetic Field Laboratory  

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

Ring Coil for Neuroimaging at 21.1 T Gregory S. Boebinger, National High Magnetic Field Laboratory DMR-Award 0654118 NMR Facility - 900MHz UWB Magnet While today s clinical...

219

National High Magnetic Field Laboratory - Science Starts Here...  

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

technology. The Magnet Lab is a wonderful environment for nurturing students in high magnetic field research. The group that I worked in conducted leading-edge research in high...

220

Planetary Magnetic Field Measurements: Missions and Instrumentation  

Science Journals Connector (OSTI)

The nature and diversity of the magnetic properties of the planets have been investigated by a large number of space missions over the past 50 years. It is clear that without the magnetic field measurements th...

André Balogh

2010-05-01T23:59:59.000Z

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


221

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

E-Print Network [OSTI]

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

Alexander J. Silenko

2007-10-02T23:59:59.000Z

222

Semiclassical Approximation for Non-Abelian Field Strength Correlators in the Instanton Dilute Gas Model  

E-Print Network [OSTI]

Field strength correlators are semi-classically evaluated in the dilute gas model of non-Abelian sources (instantons) and compared with lattice data for QCD at zero temperature. We show that one of the Euclidean invariant, tensorial structures vanishes for configurations being purely selfdual or anti-selfdual. We compute the invariant functions contributing to the correlators within the two lowest orders in an instanton density expansion. Fitting instanton size and density for quenched and full QCD, we obtain a reasonable description.

E. -M. Ilgenfritz; B. V. Martemyanov; S. V. Molodtsov; M. Müller--Preussker; Yu. A. Simonov

1997-12-26T23:59:59.000Z

223

Transport of Field Lines and Particles in a Stochastic Magnetic Field  

Science Journals Connector (OSTI)

In this chapter the transport of field lines and charged particles in a stochastic magnetic field will be investigated. To study this problem...

Sadrilla Abdullaev

2014-01-01T23:59:59.000Z

224

Vector optical fields with polarization distributions similar to electric and magnetic field lines  

Science Journals Connector (OSTI)

We present, design and generate a new kind of vector optical fields with linear polarization distributions modeling to electric and magnetic field lines. The geometric configurations...

Pan, Yue; Li, Si-Min; Mao, Lei; Kong, Ling-Jun; Li, Yongnan; Tu, Chenghou; Wang, Pei; Wang, Hui-Tian

2013-01-01T23:59:59.000Z

225

Cosmic Acceleration and Anisotropic models with Magnetic field  

E-Print Network [OSTI]

Plane symmetric cosmological models are investigated with or without any dark energy components in the field equations. Keeping an eye on the recent observational constraints concerning the accelerating phase of expansion of the universe, the role of magnetic field is assessed. The presence of magnetic field can favour an accelerating model even if we take a linear relationship between the directional Hubble parameters.

S. K. Tripathy; K. L. Mahanta

2014-07-27T23:59:59.000Z

226

Neutron scattering in magnetic fields (*) W. C. Koehler  

E-Print Network [OSTI]

691 Neutron scattering in magnetic fields (*) W. C. Koehler Solid State Division, Oak Ridge. Abstract 2014 The use of magnetic fields in neutron scattering experimentation is reviewed briefly. Two of the scattering sample ; in the second the field acts on the neutron itself. Several examples are discussed

Boyer, Edmond

227

Particle energization through time-periodic helical magnetic fields  

E-Print Network [OSTI]

We solve for the motion of charged particles in a helical time-periodic ABC (Arnold-Beltrami-Childress) magnetic field. The magnetic field lines of a stationary ABC field with coefficients A=B=C=1 are chaotic, and we show ...

Mitra, Dhrubaditya

228

E-Print Network 3.0 - aligned magnetic field Sample Search Results  

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

magnetic field Search Powered by Explorit Topic List Advanced Search Sample search results for: aligned magnetic field Page: << < 1 2 3 4 5 > >> 1 CHAPTER 20: MAGNETIC PROPERTIES...

229

Electrostatic and Magnetic Fields in Bilayer Graphene  

E-Print Network [OSTI]

We compute the transmission probability through rectangular potential barriers and p-n junctions in the presence of a magnetic and electric fields in bilayer graphene taking into account the full four bands of the energy spectrum. For energy E higher than the interlayer coupling $\\gamma_1 (E>\\gamma_1)$ two propagation modes are available for transport giving rise to four possible ways for transmission and reflection probabilities. However, when the energy is less then the height of the barrier the Dirac fermions exhibits transmission resonances and only one mode of propagation is available. We study the effect of the interlayer electrostatic potential $\\delta$ and the different geometry parameters of the barrier on the transmission probability.

Ahmed Jellal; Ilham Redouani; Hocine Bahlouli

2014-11-14T23:59:59.000Z

230

Influence of a dipole magnetic field on the topology of toroidal magnetic configurations around a gravitating body  

Science Journals Connector (OSTI)

The topological structure of the toroidal magnetic field, which is affected by a dipole magnetic field, is studied. It is shown, that a dipole magnetic field is able to split the initial toroidal configuration...

Vladimir A. Osherovich; Erast B. Gliner

231

Strongest non-destructive magnetic field: world record set at...  

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

behave under the influence of very high magnetic fields, to research into the quantum behavior of phase transitions in solids. Researchers can explore extremes of low...

232

QCD at non-zero temperature and magnetic field  

E-Print Network [OSTI]

A status of lattice QCD thermodynamics, as of 2013, is summarized. Only bulk thermodynamics is considered. There is a separate section on magnetic fields.

Kalman Szabo

2014-01-16T23:59:59.000Z

233

Synchrotron Radiation in Directions Close to Magnetic-Field Lines  

Science Journals Connector (OSTI)

It is characteristic of the radiation from a particle of mass m bearing a charge e moving with ultrarelativistic velocity ? c in a magnetic field of induction B

K. C. Westfold

1974-01-01T23:59:59.000Z

234

National High Magnetic Field Laboratory: Museum of Electricity...  

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

which at the receiving end flowed through an electromagnet. This created a magnetic field that caused the receivers metal key to be attracted to an underlying plate,...

235

High Pressure Research Questionnaire National High Magnetic Field...  

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

Pressure Research Questionnaire National High Magnetic Field Laboratory Operated by Florida State University, University of Florida, Los Alamos National Laboratory Florida State...

236

Amplifying Magnetic Fields in High Energy Density Plasmas | U...  

Office of Science (SC) Website

Amplifying Magnetic Fields in High Energy Density Plasmas Fusion Energy Sciences (FES) FES Home About Research Facilities Science Highlights Benefits of FES Funding Opportunities...

237

High Field Magnet R&D in the USA  

E-Print Network [OSTI]

Field Magnet R&D in the USA Stephen A. Gourlay Abstract··Laboratory, Berkeley, CA 94720 USA (telephone: 510-486-7156,

Gourlay, S.A.

2011-01-01T23:59:59.000Z

238

21Mathematical Model of Magnetic Field Lines -I Magnets have a north and a south  

E-Print Network [OSTI]

21Mathematical Model of Magnetic Field Lines - I Magnets have a north and a south pole. If you make this magnet small enough so that it looks like a point, all you will see are the looping lines of force mapped out by iron fillings or by using a compass. Physicists call these patterns of lines, magnetic lines

239

Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields  

E-Print Network [OSTI]

1 Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields-sized magnetizable particle is introduced into a suspension of nanosized magnetic particles, the nanoparticles and allows efficient magnetic separation of nanoparticles used in bioanalysis and water purification

Paris-Sud XI, Université de

240

Entanglement of two-qubit photon beam by magnetic field  

E-Print Network [OSTI]

We have studied the possibility of affecting the entanglement measure of 2-qubit system consisting of two photons with different fixed frequencies but with two arbitrary linear polarizations, moving in the same direction, by the help of an applied external magnetic field. The interaction between the magnetic field and the photons in our model is achieved through intermediate electrons that interact with both the photons and the magnetic field. The possibility of exact theoretical analysis of this scheme is based on known exact solutions that describe the interaction of an electron subjected to an external magnetic field (or a medium of electrons not interacting with each other) with a quantized field of two photons. We adapt these exact solutions to the case under consideration. Using explicit wave functions for the resulting electromagnetic field, we calculate the entanglement measure of the photon beam as a function of the applied magnetic field and parameters of the electron medium.

A. D. Levin; D. M. Gitman; R. C. Castro

2014-05-15T23:59:59.000Z

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


241

Magnetic Vortex Core Reversal by Low-Field Excitations  

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

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

242

Comparison of coupling of humans to electric and magnetic fields with frequencies between 100 Hz and 100 kHz  

SciTech Connect (OSTI)

Recent laboratory and epidemiological results have stimulated interest in the hypothesis that human beings may exhibit biological responses to magnetic and/or electric field transients with frequencies in the range between 100 Hz and 100 kHz. Much can be learned about the response of a system to a transient stimulation by understanding its response to sinusoidal disturbances over the entire frequency range of interest. Thus, the main effort of this paper was to compare the strengths of the electric fields induced in homogeneous ellipsoidal models by uniform 100 Hz through 100 kHz electric and magnetic fields. Over this frequency range, external electric fields of about 25--2,000 V/m (depending primarily on the orientation of the body relative to the field) are required to induce electric fields inside models of adults and children that are similar in strength to those induced by an external 1 {mu}T magnetic field. Additional analysis indicates that electric fields induced by uniform external electric and magnetic fields and by the nonuniform electric and magnetic fields produced by idealized point sources will not differ by more than a factor of two until the sources are brought close to the body. Published data on electric and magnetic field transients in residential environments indicate that, for most field orientations, the magnetic component will induce stronger electric fields inside adults and children than the electric component. This conclusion is also true for the currents induced in humans by typical levels of 60 Hz electric and magnetic fields in US residences.

Kaune, W.T. [EM Factors, Richland, WA (United States)] [EM Factors, Richland, WA (United States); Guttman, J.L. [Enertech Consultants, Campbell, CA (United States)] [Enertech Consultants, Campbell, CA (United States); Kavet, R. [Electric Power Research Inst., Palo Alto, CA (United States)] [Electric Power Research Inst., Palo Alto, CA (United States)

1997-03-01T23:59:59.000Z

243

Electric-Field Control of Magnetism Intrinsic magnetoelectric coupling describes the microscopic interaction between magnetic and  

E-Print Network [OSTI]

Electric-Field Control of Magnetism Intrinsic magnetoelectric coupling describes the microscopic interaction between magnetic and electric polarization in a single-phase material. The control of the magnetic state of a material with an electric field is an enticing prospect for device engineering. MRSEC

Maroncelli, Mark

244

Fuzzy logic based ELF magnetic field estimation in substations  

Science Journals Connector (OSTI)

......field strength in a combined cycle gas turbine power station were described...Sebo S. A., Caldecott R. Development of a computer program for modeling...buildings. (1995) Stockholm Power Technology Conference, 18-22 June. Stockholm......

Ilhan Kosalay

2008-08-01T23:59:59.000Z

245

VLBA Observations of G5.89-0.39: OH masers and magnetic field structure  

E-Print Network [OSTI]

We present VLBA observations of 1667 MHz OH maser emission from the massive star formation region G5.89-0.39. The observations were phase referenced allowing the absolute positions of the masers to be obtained. The 1667 MHz masers have radial velocities that span ~50 km/s but show little evidence of tracing the bipolar molecular outflow, as has been claimed in previous studies. We identify 23 Zeeman pairs through comparison of masers in left and right circular polarization. Magnetic field strengths range from -2 mG to +2 mG, and an ordered reversal in magnetic field direction is observed toward the southern region of the UC HII region. We suggest that the velocity and magnetic field structure of the 1667 MHz masers can be explained in the context of a model in which the masers arise in a neutral shell just outside a rapidly exanding ionized shell.

D. P. Stark; W. M. Goss; E. Churchwell; V. L. Fish; I. M. Hoffman

2006-10-05T23:59:59.000Z

246

Magnetic field contribution to the last electron-photon scattering  

E-Print Network [OSTI]

When the cosmic microwave photons scatter electrons just prior to the decoupling of matter and radiation, magnetic fields do contribute to the Stokes matrix as well as to the scalar, vector and tensor components of the transport equations for the brightness perturbations. The magnetized electron-photon scattering is hereby discussed in general terms by including, for the first time, the contribution of magnetic fields with arbitrary direction and in the presence of the scalar, vector and tensor modes of the geometry. The propagation of relic vectors and relic gravitons is discussed for a varying magnetic field orientation and for different photon directions. The source terms of the transport equations in the presence of the relativistic fluctuations of the geometry are also explicitly averaged over the magnetic field orientations and the problem of a consistent account of the small-scale and large-scale magnetic field is briefly outlined.

Giovannini, Massimo

2010-01-01T23:59:59.000Z

247

SCALING LAW FOR THE IMPACT OF MAGNET FRINGE FIELDS.  

SciTech Connect (OSTI)

A general scaling law can be derived for the relative momentum deflection produced on a particle beam by fringe fields, to leading order. The formalism is applied to two concrete examples, for magnets having dipole and quadrupole symmetry. During recent years, the impact of magnet fringe fields is becoming increasingly important for rings of relatively small circumference but large acceptance. A few years ago, following some heuristic arguments, a scaling law was proposed [1], for the relative deflection of particles passing through a magnet fringe-field. In fact, after appropriate expansion of the magnetic fields in Cartesian coordinates, which generalizes the expansions of Steffen [2], one can show that this scaling law is true for any multipole magnet, at leading order in the transverse coefficients [3]. This paper intends to provide the scaling law to estimate the impact of fringe fields in the special cases of magnets with dipole and quadrupole symmetry.

WEI,J.; PAPAPHILIPPOU,Y.; TALMAN,R.

2000-06-30T23:59:59.000Z

248

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

E-Print Network [OSTI]

Journal of Magnetism and Magnetic Materials 281 (2004) 272­275 Effects of high magnetic field annealing on texture and magnetic properties of FePd D.S. Lia, *, H. Garmestania , Shi-shen Yanb , M of Materials Science and Engineering, Georgia Institute of Technology, 771 Ferst Dr. N.W., Atlanta, GA

Garmestani, Hamid

249

Measuring and shimming the magnetic field of a 4 Tesla MRI magnet  

E-Print Network [OSTI]

The Biomedical Magnetic Resonance Laboratory (BMRL) of the University of Illinois at Urbana-Champaign (UIUC) has ordered from the Texas Accelerator Center (TAC) a superconducting, self-shielded, solenoidal magnet with a maximum field of 4 Tesla...

Kyriazis, Georgios

2012-06-07T23:59:59.000Z

250

Axion decay in a strong magnetic field and radio fluxes from magnetic white dwarfs  

Science Journals Connector (OSTI)

Radio emission of isolated magnetic white dwarfs due to invisible axions decay in a strong magnetic field is estimated. It is possible to reach theoretical limits on the abundance and coupling of cosmic axions...

Yu. N. Gnedin

1990-07-01T23:59:59.000Z

251

Magnetic Vortex Core Reversal by Low-Field Excitations  

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

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

252

Magnetic Vortex Core Reversal by Low-Field Excitations  

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

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

253

Magnetic Vortex Core Reversal by Low-Field Excitations  

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

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

254

Biological Effects of Electrical and Magnetic Fields: Is It Real?  

E-Print Network [OSTI]

The hazardous effect of electric and magnetic fields on biological systems is the subject of considerable debate. Traditional methods have failed to provide a correlation between the fields and biological effects. A model is presented that solves...

Durham, M. O.

255

A variable-field permanent-magnet dipole for accelerators  

SciTech Connect (OSTI)

A new concept for a variable-field permanent-magnet dipole has been developed and fabricated at Los Alamos. The application requires an extremely uniform dipole field in the magnet aperture and precision variability over a large operating range. An iron-core permanent- magnet design using a shunt that was specially shaped to vary the field in a precise and reproducible fashion with shunt position. The key to this design is in the shape of the shunt. The field as a function of shunt position is very linear from 90% of the maximum field to 20% of the minimum field. The shaped shunt also results in a small maximum magnetic force attracting the shunt to the yoke allowing a simple mechanical design. Calculated and measured results agree well for the magnet.

Kraus, R.H. Jr.; Barlow, D.B.; Meyer, R.

1992-01-01T23:59:59.000Z

256

A variable-field permanent-magnet dipole for accelerators  

SciTech Connect (OSTI)

A new concept for a variable-field permanent-magnet dipole has been developed and fabricated at Los Alamos. The application requires an extremely uniform dipole field in the magnet aperture and precision variability over a large operating range. An iron-core permanent- magnet design using a shunt that was specially shaped to vary the field in a precise and reproducible fashion with shunt position. The key to this design is in the shape of the shunt. The field as a function of shunt position is very linear from 90% of the maximum field to 20% of the minimum field. The shaped shunt also results in a small maximum magnetic force attracting the shunt to the yoke allowing a simple mechanical design. Calculated and measured results agree well for the magnet.

Kraus, R.H. Jr.; Barlow, D.B.; Meyer, R.

1992-09-01T23:59:59.000Z

257

Including stereoscopic information in the reconstruction of coronal magnetic fields  

E-Print Network [OSTI]

We present a method to include stereoscopic information about the three dimensional structure of flux tubes into the reconstruction of the coronal magnetic field. Due to the low plasma beta in the corona we can assume a force free magnetic field, with the current density parallel to the magnetic field lines. Here we use linear force free fields for simplicity. The method uses the line of sight magnetic field on the photosphere as observational input. The value of $\\alpha$ is determined iteratively by comparing the reconstructed magnetic field with the observed structures. The final configuration is the optimal linear force solution constrained by both the photospheric magnetogram and the observed plasma structures. As an example we apply our method to SOHO MDI/EIT data of an active region. In the future it is planned to apply the method to analyse data from the SECCHI instrument aboard the STEREO mission.

T. Wiegelmann; T. Neukirch

2008-01-23T23:59:59.000Z

258

Quark mass dependence of the vacuum electric conductivity induced by the magnetic field in SU(2) lattice gluodynamics  

SciTech Connect (OSTI)

We study the electric conductivity induced by the magnetic field B in quenched SU(2) lattice gauge theory at a finite temperature below the deconfinement phase transition as a function of the bare quark mass m{sub q} in the range m{sub q}=55 MeV...540 MeV. At fixed quark mass, the conductivity grows linearly with the magnetic field strength |B|. The proportionality coefficient in this dependence increases towards smaller quark masses and seems to saturate at some finite value in the zero-mass limit. The nonanalytic dependence on the field strength might result from the mixing between vector mesons and pions in an external magnetic field. We discuss the implications of our results for dilepton angular distributions in heavy-ion collisions.

Buividovich, P. V. [ITEP, 117218 Russia, Moscow, B. Cheremushkinskaya str. 25 (Russian Federation); JINR, 141980 Russia, Moscow Region, Dubna, Joliot-Curie str. 6 (Russian Federation); Polikarpov, M. I. [ITEP, 117218 Russia, Moscow, B. Cheremushkinskaya str. 25 (Russian Federation)

2011-05-01T23:59:59.000Z

259

Nuclear magnetic absorption line widths in weak magnetic fields with a Robinson oscillator  

E-Print Network [OSTI]

NUCLEAR MAGNETIC ABSORPTION LINE WIDTHS IN WEAK MAGNETIC FIELDS WITH A ROBINSON OSCILLATOR A Thesis by TIMOTHY LEE FLUGUM Subnntted to the Graduate College of Texas ARM University in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE August 19SI Major Subject: Physics NUCLEAR MAGNETIC ABSORPTION LINE WIDTHS IN WEAK MAGNETIC FIELDS WITH A ROBINSON OSCILLATOR A Thesis TIMOTHY LEE FLUGUM Approved as to style and content by: Nelson M. Duller (Chairman...

Flugum, Timothy Lee

1987-01-01T23:59:59.000Z

260

Development of magnetic separation methods of analysis: magnetic field flow fractionation  

E-Print Network [OSTI]

of MASTER OF SCIENCE August 1980 Major Subject: Chemistry DEVELOPMENT OF MAGNETIC SEPARATION METHODS OF ANALYSIS: MAGNETIC FIELD FLOW FRACTIONATION A Thesis by JAIME GARCIA-RAMIREZ Approved as to style and content by: (Chairman of Committee) 1... of MASTER OF SCIENCE August 1980 Major Subject: Chemistry DEVELOPMENT OF MAGNETIC SEPARATION METHODS OF ANALYSIS: MAGNETIC FIELD FLOW FRACTIONATION A Thesis by JAIME GARCIA-RAMIREZ Approved as to style and content by: (Chairman of Committee) 1...

Garcia-Ramirez, Jaime

2012-06-07T23:59:59.000Z

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


261

National High Magnetic Field Laboratory - Magnets and Materials...  

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

Applied Superconductivity Center, please see the center's group members page. Magnet Science & Technology Group Members Senior Personnel Bai, Hongyu Research Faculty II Phone:...

262

National High Magnetic Field Laboratory - Magnets and Materials...  

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

which joined the Magnet Lab and Florida State University in 2006. The ASC advances the science and technology of superconductivity by investigating low temperature and high...

263

National High Magnetic Field Laboratory - Mission  

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

research to serve an interdisciplinary scientific user community spanning materials science, condensed matter physics, magnet technology, chemistry, and biology. Provide...

264

Electron pitch angle distributions as indicators of magnetic field topology near Mars  

E-Print Network [OSTI]

magnetic field lines are associated with the Martian crustal magnetic fields and are identified. Open magnetic field lines are identified in regions of strong crustal magnetic field by the absence and that the drift motion of particles across field lines is small. In any system with two sources of magnetic field

California at Berkeley, University of

265

Ion flux from vacuum arc cathode spots in the absence and presence of a magnetic field  

SciTech Connect (OSTI)

Because plasma production at vacuum cathode spots is approximately proportional to the arc current, arc current modulation can be used to generate ion current modulation that can be detected far from the spot using a negatively biased ion collector. The drift time to the ion detector can used to determine kinetic ion energies. A very wide range of cathode materials have been used. It has been found that the kinetic ion energy is higher at the beginning of each discharge and approximately constant after 150 {micro}s. The kinetic energy is correlated with the arc voltage and the cohesive energy of the cathode material. The ion erosion rate has in inverse relation to the cohesive energy, enhancing the effect that the power input per plasma particle correlates with the cohesive energy of the cathode material. The influence of three magnetic field configurations on the kinetic energy has been investigated. Generally, a magnetic field increases the plasma impedance, arc burning voltage, and kinetic ion energy. However, if the plasma is produced in a region of low field strength and streaming into a region of higher field strength, the velocity may decrease due to the mirror effect. A magnetic field can increase the plasma temperature but may reduce the density gradients by preventing free expansion into vacuum. Therefore, depending on the configuration, a magnetic field may increase or decrease the kinetic energy of ions. Additionally, the angular distribution of the ion flux and ion kinetic energy has been investigated in the absence of an external magnetic field. The result can be fitted by a superposition of an isotropic and a cosine distribution.

Anders, Andre; Yushkov, George Yu.

2001-10-02T23:59:59.000Z

266

Comparison of transient horizontal magnetic fields in a plage region and in the quiet Sun  

E-Print Network [OSTI]

Properties of transient horizontal magnetic fields (THMFs) in both plage and quiet Sun regions are obtained and compared. Spectro-polarimetric observations with the Solar Optical Telescope (SOT) on the Hinode satellite were carried out with a cadence of about 30 seconds for both plage and quiet regions located near disk center. We select THMFs that have net linear polarization (LP) higher than 0.22%, and an area larger than or equal to 3 pixels, and compare their occurrence rates and distribution of magnetic field azimuth. We obtain probability density functions (PDFs) of magnetic field strength and inclination for both regions.The occurrence rate in the plage region is the same as for the quiet Sun. The vertical magnetic flux in the plage region is ~8 times larger than in the quiet Sun. There is essentially no preferred orientation for the THMFs in either region. However, THMFs in the plage region with higher LP have a preferred direction consistent with that of the plage-region's large-scale vertical field pattern. PDFs show that there is no difference in the distribution of field strength of horizontal fields between the quiet Sun and the plage regions when we avoid the persistent large vertical flux concentrations for the plage region. The similarity of the PDFs and of the occurrence rates in plage and quiet regions suggests that a local dynamo process due to the granular motion may generate THMFs all over the sun. The preferred orientation for higher LP in the plage indicates that the THMFs are somewhat influenced by the larger-scale magnetic field pattern of the plage.

Ryohko Ishikawa; Saku Tsuneta

2008-12-09T23:59:59.000Z

267

The role of magnetic fields in hyperon stars  

SciTech Connect (OSTI)

We investigate the effects of strong magnetic fields (SMF) on the properties of neutron stars that have hyperons in their composition. The matter is described by a hadronic model in which a parameterized and derivative coupling between hadrons and mesons is considered. We study the magnetic effects on the equation of state (EoS) from Landau quantization, assuming a density dependent static magnetic field that reaches 10{sup 19} G in the center of the star. The Tolman- Oppenheimer-Volkoff (TOV) equations are solved in order to show the dependence of the massradius relation and population of hyperon stars on the central magnetic field and on different hyperon coupling schemes.

Gomes, R. O.; Vasconcellos, C. A. Z. [Instituto de Física - Universidade Federal do Rio Grande do Sul, Porto Alegre, RS 91501-970 (Brazil); Dexheimer, V. [Department of Physics - Kent State University, Kent, OH 44242 (United States)

2014-05-09T23:59:59.000Z

268

Spin diffusion at finite electric and magnetic fields  

Science Journals Connector (OSTI)

Spin-transport properties at finite electric and magnetic fields are studied by using the generalized semiclassical Boltzmann equation. It is found that the spin-diffusion equation for nonequilibrium spin density and spin currents involves a number of length scales that explicitly depend on the electric and magnetic fields. The set of macroscopic equations can be used to address a broad range of the spin-transport problems in magnetic multilayers as well as in semiconductor heterostructure. A specific example of spin injection into semiconductors at arbitrary electric and magnetic fields is illustrated.

Y. Qi and S. Zhang

2003-02-27T23:59:59.000Z

269

Sidewall containment of liquid metal with vertical alternating magnetic fields  

DOE Patents [OSTI]

An apparatus is disclosed for containing molten metal using a magnet producing vertical alternating magnetic field positioned adjacent the area in which the molten metal is to be confined. This invention can be adapted particularly to the casting of metal between counter-rotating rollers with the vertical alternating magnetic field used to confine the molten metal at the edges of the rollers. Alternately, the vertical alternating magnetic field can be used as a flow regulator in casting molten metal from an opening in a channel. 9 figs.

Lari, R.J.; Praeg, W.F.; Turner, L.R.; Battles, J.E.; Hull, J.R.; Rote, D.M.

1990-12-04T23:59:59.000Z

270

Sidewall containment of liquid metal with vertical alternating magnetic fields  

DOE Patents [OSTI]

An apparatus for containing molten metal using a magnet producing vertical alternating magnetic field positioned adjacent to the area in which the molten metal is to be confined. This invention can be adapted particularly to the casting of metal between counter-rotating rollers with the vertical alternating magnetic field used to confine the molten metal at the edges of the rollers. Alternately, the vertical alternating magnetic field can be used as a flow regulator in casting molten metal from an opening in a channel. 8 figs.

Lari, R.J.; Praeg, W.F.; Turner, L.R.; Battles, J.E.; Hull, J.R.; Rote, D.M.

1988-06-17T23:59:59.000Z

271

Magnetism of a relativistic degenerate electron gas in a strong magnetic field  

SciTech Connect (OSTI)

The magnetization and magnetic susceptibility of a degenerate electron gas in a strong magnetic field in which electrons are located on the ground Landau level and the electron gas has the properties of a nonlinear paramagnet have been calculated. The paradoxical properties of the electron gas under these conditions-a decrease in the magnetization with the field and an increase in the magnetization with the temperature-have been revealed. It has been shown that matter under the corresponding conditions of neutron stars is a paramagnet with a magnetic susceptibility of {chi} {approx} 0.001.

Skobelev, V. V., E-mail: v.skobelev@inbox.ru [Moscow State Industrial University (Russian Federation)

2012-09-15T23:59:59.000Z

272

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

Science Journals Connector (OSTI)

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

G. Zimbardo and P. Veltri

1995-02-01T23:59:59.000Z

273

Model of a magnetic field in poloidal divertor tokamaks affected by resonant magnetic perturbations  

SciTech Connect (OSTI)

A generic analytical model for the description of magnetic field lines in poloidal divertor tokamaks in the presence of external resonant magnetic perturbations is proposed. It is based on the Hamiltonian description of magnetic field lines in tokamaks. The safety factor and the spectra of magnetic perturbations are chosen by the requirement to satisfy their generic behavior near the magnetic separatrix and at the magnetic axis. The field line equations of the model are integrated using symplectic efficient mappings of field lines. The analytical formulas for the quasilinear diffusion and convection coefficients of field lines are obtained. The latter describes the outwardly directed transport of field lines at the plasma edge. It was shown that they are in a good agreement with the corresponding numerically calculated coefficients.

Abdullaev, S. S. [Forschungszentrum Juelich GmbH, Institute of Energy Research IEF-4: Plasma Physics, Association EURATOM-FZJ, Partner in the Trilateral Euregio Cluster, 52425 Juelich (Germany)

2009-03-15T23:59:59.000Z

274

2.6 ELECTRIC AND MAGNETIC FIELDS Introduction  

E-Print Network [OSTI]

325 §2.6 ELECTRIC AND MAGNETIC FIELDS Introduction In electromagnetic theory the mks system MKS units Replacement symbol GAUSSIAN units # E (Electric field) volt/m # E statvolt/cm # B (Magnetic potential) weber/m # A c gauss­cm V (Electric potential) volt V statvolt # (Dielectric constant) # 4# µ

California at Santa Cruz, University of

275

Studies of Cryogenic Electron Plasmas in Magnetic Mirror Fields  

E-Print Network [OSTI]

Studies of Cryogenic Electron Plasmas in Magnetic Mirror Fields by Ramesh Gopalan A.B. (University: Chair Date Date Date University of California at Berkeley 1998 #12;Studies of Cryogenic Electron Plasmas in Magnetic Mirror Fields Copyright 1998 by Ramesh Gopalan #12;1 Abstract Studies of Cryogenic Electron

Fajans, Joel

276

Breaking van der Waals Molecules with Magnetic Fields  

Science Journals Connector (OSTI)

It is demonstrated that weakly bound van der Waals complexes can dissociate in a magnetic field through coupling between the Zeeman levels. The Zeeman predissociation process is shown to be efficient and it can be controlled by external magnetic fields.

R. V. Krems

2004-06-28T23:59:59.000Z

277

Phase transitions in quark matter under strong magnetic fields  

SciTech Connect (OSTI)

In this work we use de SU(2) Nambu-Jona-Lasinio model to study the chiral transition at finite temperature, chemical potential and magnetic field. We show how the magnetic field affects the location of the critical end-point in the phase diagram, the constituent quark masses and the spinodal lines concerning the first order transition.

Garcia, Andre F.; Pinto, Marcus B. [Physics Department, Universidade Federal de Santa Catarina (Brazil)

2013-03-25T23:59:59.000Z

278

TWO FREEDERICKSZ TRANSITIONS IN CROSSED ELECTRIC AND MAGNETIC FIELDS  

E-Print Network [OSTI]

965 TWO FREEDERICKSZ TRANSITIONS IN CROSSED ELECTRIC AND MAGNETIC FIELDS H. J. DEULING-p-dibu- tylazoxybenzène. Abstract. 2014 A planar nematic slab shows a Freedericksz transition in a perpendicular electric by external electric or magnetic fields. The resulting distortion is governed by a balance of stabilizing

Boyer, Edmond

279

THE VIBRATION OF A CONDUCTING WIRE IN A MAGNETIC FIELD  

Science Journals Connector (OSTI)

......1963 research-article Articles THE VIBRATION OF A CONDUCTING WIRE IN A MAGNETIC FIELD...Polytechnic Institute of Brooklyn. The vibration of a perfectly flexible, stretched...inpedance of the wire is discuassed. THE VIBRATION OF A CONDUCTING WIRE IN A MAGNETIC FIELD......

M.A. LEIBOWITZ; R.C. ACKERBERG

1963-11-01T23:59:59.000Z

280

An investigation into the vector ellipticity of extremely low frequency magnetic fields from appliances in UK homes  

Science Journals Connector (OSTI)

Elliptically polarized magnetic fields induce higher currents in the body compared with their plane polarized counterparts. This investigation examines the degree of vector ellipticity of extremely low frequency magnetic fields (ELF-MFs) in the home, with regard to the adverse health effects reportedly associated with ELF-MFs, for instance childhood leukaemia. Tri-axial measurements of the magnitude and phase of the 0?3000 Hz magnetic fields, produced by 226 domestic mains-fed appliances of 32 different types, were carried out in 16 homes in Worcestershire in the summer of 2004. Magnetic field strengths were low, with average (RMS) values of 0.03 ? 0.02 ?T across all residences. In contrast, background field ellipticities were high, on average 47 ? 11%. Microwave and electric ovens produced the highest ellipticities: mean respective values of 21 ? 21% and 21 ? 17% were observed 20 cm away from these appliances. There was a negative correlation between field strength and field polarization, which we attribute to the higher relative field contribution close to each individual (single-phase) appliance. The measurements demonstrate that domestic magnetic fields are extremely complex and cannot simply be characterized by traditional measurements such as time-weighted average or peak exposure levels. We conclude that ellipticity should become a relevant metric for future epidemiological studies of health and ELF-MF exposure.

Elizabeth A Ainsbury; Emma Conein; Denis L Henshaw

2005-01-01T23:59:59.000Z

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


281

Ground state of the H{sub 2}{sup +} molecule in oblique magnetic fields  

SciTech Connect (OSTI)

Calculations in the Born-Oppenheimer approximation of curves for the ground-state energy of the H{sub 2}{sup +} ion vs the separation, R, of its protons in magnetic fields making oblique angles {theta} with the line connecting the protons have recently been published. It is shown here that these curves are qualitatively incorrect. The variational trial function employed fails to approximate well the wave function of the H{sub 2}{sup +} ground state for oblique fields, even though this function gives very accurate results for {theta}=0. A trial function is proposed which gives much more accurate potential curves in oblique fields. It is used to plot and tabulate ground-state binding energies for various values of {theta}, R, and magnetic field strength.

Larsen, David M

2007-10-15T23:59:59.000Z

282

Plasma-satellite interaction driven magnetic field perturbations  

SciTech Connect (OSTI)

We report the first fully kinetic quantitative estimate of magnetic field perturbations caused by the interaction of a spacecraft with space environment. Such perturbations could affect measurements of geophysical magnetic fields made with very sensitive magnetometers on-board satellites. Our approach is illustrated with a calculation of perturbed magnetic fields near the recently launched Swarm satellites. In this case, magnetic field perturbations do not exceed 20 pT, and they are below the sensitivity threshold of the on-board magnetometers. Anticipating future missions in which satellites and instruments would be subject to more intense solar UV radiation, however, it appears that magnetic field perturbations associated with satellite interaction with space environment, might approach or exceed instruments' sensitivity thresholds.

Saeed-ur-Rehman, E-mail: surehman@ualberta.ca [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1 (Canada); Theoretical Physics Division, PINSTECH, Nilore Islamabad 44000 (Pakistan); Marchand, Richard, E-mail: Richard.Marchand@ualberta.ca [Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1 (Canada)

2014-09-15T23:59:59.000Z

283

GRB Phenomenology, Shock Dynamo, and the First Magnetic Fields  

E-Print Network [OSTI]

A relativistic collisionless shock propagating into an unmagnetized medium leaves behind a strong large-scale magnetic field. This seems to follow from two assumptions: (i) GRB afterglows are explained by synchrotron emission of a relativistic shock, (ii) magnetic field can't exist on microscopic scales only, it would decay by phase space mixing. Assumption (i) is generally accepted because of an apparent success of the shock synchrotron phenomenological model of GRB afterglow. Assumption (ii) is confirmed in this work by a low-dimensional numerical simulation. One may hypothesize that relativistic shock velocities are not essential for the magnetic field generation, and that all collisionless shocks propagating into an unmagnetized medium generate strong large-scale magnetic fields. If this hypothesis is true, the first cosmical magnetic fields could have been generated in shocks of the first virialized objects.

Andrei Gruzinov

2001-07-05T23:59:59.000Z

284

1982 IEEE TRANSACTIONS ON MAGNETICS, VOL. 44, NO. 8, AUGUST 2008 Analytical Calculation of the Magnetic Field Created  

E-Print Network [OSTI]

]. It is noticeable that in some applications, such as permanent-magnet motors [18] or magnetic couplings [19], tiles of the Magnetic Field Created by Permanent-Magnet Rings R. Ravaud, G. Lemarquand, V. Lemarquand, and C. Depollier analytical formulations, based on a coulombian approach, of the magnetic field created by permanent-magnet

Paris-Sud XI, Université de

285

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

SciTech Connect (OSTI)

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

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

2008-07-01T23:59:59.000Z

286

Complex atomic spectral line shapes in the presence of an external magnetic field  

Science Journals Connector (OSTI)

Both the theoretical basis and the computational approach for extending the capabilities of an established spectral line broadening code are presented. By following standard line broadening theory, the effects of an external magnetic field are incorporated into the plasma average and atomic Hamiltonian. An external magnetic field introduces a preferential axis that destroys the symmetry of the quasistatic electric ion microfield. An external magnetic field also modifies the angular properties of the atomic Hamiltonian—atomic energy levels are perturbed and the spectral emission line is polarized. These extensions have been incorporated in an atomic line shape code for complex atoms and applied to several problems of importance to the understanding of tokamak edge plasmas. Applications fall into two broad categories: (1) determination of local plasma properties, such as the magnetic field strength, from distinct line shape features; and (2) consideration of global plasma phenomenon, such as radiation transport. Observable features of the Zeeman effect make H? a good line for diagnosing the magnetic field. H? does not make a good electron density diagnostic since the Zeeman effect is comparable to the Stark effect for a majority of tokamak edge plasma conditions. For optically thick lines, the details of the spectral line shapes are shown to significantly influence the transport of radiation throughout the system.

M. L. Adams; R. W. Lee; H. A. Scott; H. K. Chung; L. Klein

2002-12-20T23:59:59.000Z

287

Magnetic Fields in High-Mass Infrared Dark Clouds  

E-Print Network [OSTI]

High-mass Stars are cosmic engines known to dominate the energetics in the Milky Way and other galaxies. However, their formation is still not well understood. Massive, cold, dense clouds, often appearing as Infrared Dark Clouds (IRDCs), are the nurseries of massive stars. No measurements of magnetic fields in IRDCs in a state prior to the onset of high-mass star formation (HMSF) have previously been available, and prevailing HMSF theories do not consider strong magnetic fields. Here, we report observations of magnetic fields in two of the most massive IRDCs in the Milky Way. We show that IRDCs G11.11-0.12 and G0.253+0.016 are strongly magnetized and that the strong magnetic field is as important as turbulence and gravity for HMSF. The main dense filament in G11.11-0.12 is perpendicular to the magnetic field, while the lower density filament merging onto the main filament is parallel to the magnetic field. The implied magnetic field is strong enough to suppress fragmentation sufficiently to allow HMSF. Other ...

Pillai, Thushara; Tan, Jonathan; Goldsmith, Paul; Carey, Sean; Menten, Karl

2014-01-01T23:59:59.000Z

288

Capillary instability of the cylindrical interface between ferrofluids in a magnetic field with circular field lines  

Science Journals Connector (OSTI)

Capillary breakup of a viscous magnetic fluid layer subjected to a gradient magnetic field under hydroweightlessness is studied within the linear theory. The cylinder surface of a current-carrying conductor se...

V. M. Korovin

2001-12-01T23:59:59.000Z

289

Analysis of magnetic fields produced far from electric power lines  

SciTech Connect (OSTI)

In this paper, the authors develop a simple and general method for analyzing the magnetic fields produced by power lines at far distances, that is, at distances large in comparison to the spacing between the line's phase conductors. Magnetic fields produced far from conventional power lines have remarkably simple properties. The authors present formulae for the fields produced by various conventional and unconventional power line configurations; included are line designs characterized by reduced magnetic-field levels. Errors in the formulae are less than [plus minus]10% at the edge of a typical transmission right-of-way.

Kaune, W.T. (Enertech Consultants Campbell, CA (United States)); Zaffanella, L.E. (High Voltage Transmission Research Center, Lenox, MA (United States))

1992-10-01T23:59:59.000Z

290

Magnetic Field Production during Preheating at the Electroweak Scale  

Science Journals Connector (OSTI)

We study the generation of magnetic fields during preheating within a scenario of hybrid inflation at the electroweak scale. We find that the nonperturbative and strongly out-of-equilibrium process of generation of magnetic fields with a nontrivial helicity occurs along the lines predicted by Vachaspati many years ago. The magnitude (?B/?EW?10-2) and correlation length of these helical magnetic fields grow linearly with time during preheating and are consistent with the possibility that these seeds gave rise to the microgauss fields observed today in galaxies and clusters of galaxies.

Andrés Díaz-Gil; Juan García-Bellido; Margarita García Pérez; Antonio González-Arroyo

2008-06-16T23:59:59.000Z

291

Development for Hardware for Programming of Spatial Magnetic Field Distributions in Nuclear Magnetic Resonance and Magnetic Resonance Imaging  

E-Print Network [OSTI]

The proposal of a project aimed on a design of hardware for programming 3D Magnetic Field shapes over sample volume in NMR and MRI is described.

Vladimir Korostelev

2012-01-13T23:59:59.000Z

292

National High Magnetic Field Laboratory: Magnetic Thin Films  

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

recorded work with magnetic thin films took place in the 1880s and was carried out by German physicist August Kundt. Well known for his research on sound and optics, Kundts...

293

National High Magnetic Field Laboratory - Basic Science  

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

fruits of Faraday's discovery of electromagnetic induction. A more recent example is magnetic resonance imaging (MRI), which originated in basic research that started in the...

294

Superconducting trapped-field magnets: Temperature and field distributions during pulsed-field activation  

E-Print Network [OSTI]

progress in fabrication of large-sized high- temperature superconductors with high critical current den We calculate the temperature and magnetic field distributions in a bulk superconductor during leads to a strong temperature rise in superconductor during the activation pro- cess. There have already

Johansen, Tom Henning

295

Observation of field-reversed configurations with spheromak magnetic field profiles  

Science Journals Connector (OSTI)

We report the first observation of field-reversed configurations with nearly force-free magnetic fields in the central region of the compact toroid. The field profiles and flux ratios suggest that some form of relaxation phenomenon is occurring in this high-? kinetic regime. The magnetic helicity of the translating plasmas arises from axial asymmetry, possibly through end-shorting Alfvén waves.

M. Tuszewski and B. L. Wright

1989-11-13T23:59:59.000Z

296

Los Alamos achieves world-record pulsed magnetic field  

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

Los Alamos achieves world-record pulsed magnetic field Los Alamos achieves world-record pulsed magnetic field Los Alamos achieves world-record pulsed magnetic field Researchers have set a new world record for the strongest magnetic field produced by a nondestructive magnet. August 23, 2011 Los Alamos National Laboratory sits on top of a once-remote mesa in northern New Mexico with the Jemez mountains as a backdrop to research and innovation covering multi-disciplines from bioscience, sustainable energy sources, to plasma physics and new materials. Los Alamos National Laboratory sits on top of a once-remote mesa in northern New Mexico with the Jemez mountains as a backdrop to research and innovation covering multi-disciplines from bioscience, sustainable energy sources, to plasma physics and new materials.

297

Analysis of Reccurent Patterns in Toroidal Magnetic Fields  

SciTech Connect (OSTI)

In the development of magnetic confinement fusion which will be a future source for low cost power, physicists must be able to analyze the magnetic field that confines the burning plasma. While the magnetic field can be described as a series of vectors, traditional techniques for analyzing the field s topology can not be used because of its homoclinic nature. In this paper we describe a technique developed as a collaboration between physicists and computer scientists that determines the topology of a toroidal magnetic field using fieldlines with near minimal lengths. More specifically, we analyze the Poincare map of the sampled fieldlines in a Poincare section including identifying critical points and other topological features of interest to physicists. The technique has been deployed into an interactive parallel visualization tool which physicists are using to gain new insight into simulations of magnetically confined buring plasmas.

Sanderson, Allen [University of Utah; Pugmire, Dave [ORNL

2010-11-01T23:59:59.000Z

298

Monitoring the magnetic field in houses under 50 Hz high-voltage overhead transmission lines  

Science Journals Connector (OSTI)

This paper deals with a one-week monitoring of the 50 Hz magnetic field on the ground floor and the first floor of houses under 150, 220 and 380 kV high-voltage overhead three-phase AC transmission lines. The field strength varied with the current intensity, the conductor height, and the storey of the house. Because current intensity varies with time the magnetic field depended on the time of day and the day of the week. The recorded magnetic field ranged from 0.1 µT to 4.5 µT. The maximum value was at least 20 times weaker than the 100 µT exposure level recommended by the guidelines of the International Radiation Protection Association (IRPA) and about 140 times smaller than the 640 µT of the European Prestandard (CENELEC). The B-field was, for 99.9% of the measuring time, larger than the 0.2 µT cut-off point used to define categories of exposed and unexposed subjects in EMF epidemiological studies and, for 99.3% of the time, was greater than the 0.3 µT level used by US private engineering companies as the 'prudent avoidance' exposure limit. The weakest average magnetic field was at least 40 times larger than the 0.02 µT background value.

G. Decat; J. Van Tongerloo

1998-01-01T23:59:59.000Z

299

Magnetic field effects on the thermonuclear combustion front of Chandrasekhar mass white dwarfs  

E-Print Network [OSTI]

The explosion of a type Ia supernova starts in a white dwarf as a laminar deflagration at the center of the star and soon several hydrodynamic instabilities, in particular, the Rayleigh-Taylor instability, begin to act. A cellular stationary combustion and a turbulent combustion regime are rapidly achieved by the flame and maintained up to the end of the so-called flamelet regime when the transition to detonation is believed to occur. The burning velocity at these regimes is well described by the fractal model of combustion. Using a semi-analytic approach, we describe the effect of magnetic fields on the fractalization of the front considering a white dwarf with a nearly dipolar magnetic field. We find an intrinsic asymmetry on the velocity field that may be maintained up to the free expansion phase of the remnant. Considering the strongest values inferred for a white dwarf's magnetic fields with strengths up to $10^{8}-10^{9}$ G at the surface and assuming that the field near the centre is roughly 10 times greater, asymmetries in the velocity field higher than $10-20 %$ are produced between the magnetic polar and the equatorial axis of the remnant which may be related to the asymmetries found from recent spectropolarimetric observations of very young SN Ia remnants. Dependence of the asymmetry with white dwarf composition is also analyzed.

Cristian R. Ghezzi; Elisabete M. de Gouveia Dal Pino; Jorge E. Horvath

2000-12-06T23:59:59.000Z

300

National High Magnetic Field Laboratory - DC Field Program: Portable...  

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

Portable Dilution Refrigerator Portable Dilution Refrigerator Portable Dilution Refrigerator installed in the 45T hybrid magnet. A portable dilution refrigerator (PDF) is available...

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


301

Directly Mapping Magnetic Field Effects of Neuronal Activity by Magnetic Resonance  

E-Print Network [OSTI]

Directly Mapping Magnetic Field Effects of Neuronal Activity by Magnetic Resonance Imaging Jinhu Xiong,* Peter T. Fox, and Jia-Hong Gao Research Imaging Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas Abstract: Magnetic resonance imaging (MRI) of brain functional

Gabrieli, John

302

Bose Glass of Quasiparticles in Doped Quantum Magnet Gregory S. Boebinger, National High Magnetic Field Laboratory  

E-Print Network [OSTI]

Bose Glass of Quasiparticles in Doped Quantum Magnet Gregory S. Boebinger, National High Magnetic. This BEC can localize in the presence of disorder caused by Br- doping to form a Bose Glass. The BEC-Bose Glass (BEC-BG) transition can be carefully controlled by magnetic field, allowing us to sensitively

Weston, Ken

303

Magnetic Helicity and the Relaxation of Fossil Fields  

E-Print Network [OSTI]

In the absence of an active dynamo, purely poloidal magnetic field configurations are unstable to large-scale dynamical perturbations, and decay via reconnection on an Alfvenic timescale. Nevertheless, a number of classes of dynamo-free stars do exhibit significant, long-lived, surface magnetic fields. Numerical simulations suggest that the large-scale poloidal field in these systems is stabilized by a toroidal component of the field in the stellar interior. Using the principle of conservation of total helicity, we develop a variational principle for computing the structure of the magnetic field inside a conducting sphere surrounded by an insulating vacuum. We show that, for a fixed total helicity, the minimum energy state corresponds to a force-free configuration. We find a simple class of axisymmetric solutions, parametrized by angular and radial quantum numbers. However, these solutions have a discontinuity in the toroidal magnetic field at the stellar surface which will exert a toroidal stress on the surface of the star. We then describe two other classes of solutions, the standard spheromak solutions and ones with fixed surface magnetic fields, the latter being relevant for neutron stars with rigid crusts. We discuss the implications of our results for the structure of neutron star magnetic fields, the decay of fields, and the origin of variability and outbursts in magnetars.

Avery E. Broderick; Ramesh Narayan

2007-02-05T23:59:59.000Z

304

The Light Curve and Internal Magnetic Field of the Mode-Switching Pulsar PSR B0943+10  

E-Print Network [OSTI]

A number of radio pulsars exhibit intriguing mode-switching behavior. Recent observations of PSR B0943+10 revealed correlated radio and X-ray mode switches, providing a new avenue for understanding this class of objects. The large X-ray pulse fraction observed during the radio quiet phase (Q mode) was previously interpreted as a result of changing obscuration of X-rays by dense magnetosphere plasma. We show that the large X-ray pulse fraction can be explained by including the beaming effect of a magnetic atmosphere, while remaining consistent with the dipole field geometry constrained by radio observations. We also explore a more extreme magnetic field configuration, where a magnetic dipole displaced from the center of the star produces two magnetic polar caps of different sizes and magnetic field strengths. These models are currently consistent with data in radio and X-rays and can be tested or constrained by future X-ray observations.

Storch, Natalia I; Lai, Dong; Bogdanov, Slavko; Heinke, Craig O

2014-01-01T23:59:59.000Z

305

On the magnetic fields in voids  

Science Journals Connector (OSTI)

......estimate the transport of magnetic energy by cosmic rays (CR) from the...small fraction of the magnetic energy contained in the void galaxies...809. Longair M. S. High Energy Astrophysics (2010) Cambridge...Pogorelov N. V., Font J. A., Audit E., Zank G. P., eds......

A. M. Beck; M. Hanasz; H. Lesch; R.-S. Remus; F. A. Stasyszyn

2013-01-01T23:59:59.000Z

306

Abstract--Temperature, current density and magnetic field distributions in YBCO bulk superconductor during a pulsed-field  

E-Print Network [OSTI]

-- bulk YBaCuO, stored magnetic energy, thermal coupling, magnetization, modelling. I. INTRODUCTION HE as cryo-permanent magnets [1], [2]. To magnetize the HTS, pulsed field magnetization (PFM) process1 Abstract-- Temperature, current density and magnetic field distributions in YBCO bulk

Paris-Sud XI, Université de

307

Geometric properties of magnetic field lines on toroidal magnetic surfaces in the context of plasma equilibrium  

SciTech Connect (OSTI)

An analysis of plasma equilibrium in a magnetic confinement system includes studies of how the shape of the magnetic surfaces is distorted with varying magnitude and profile of the plasma pressure. Such studies allow one, in particular, to determine the maximum {beta} value consistent with equilibrium, {beta}{sub eq}, i.e., the maximum plasma pressure above which the equilibrium in a confinement system under analysis is impossible. Since the magnetic field lines form magnetic surfaces, their global relationship with equilibrium is obvious. Here, special attention is paid to a local relationship between equilibrium and geometric properties of the magnetic field lines.

Skovoroda, A. A. [Russian Research Centre Kurchatov Institute, Nuclear Fusion Institute (Russian Federation)

2007-08-15T23:59:59.000Z

308

Models of magnetic-field evolution and effective viscosity in weakly collisional extragalactic plasmas  

E-Print Network [OSTI]

In weakly collisional extragalactic plasmas such as the intracluster medium, viscous stress and the rate of change of the magnetic-field strength are proportional to the local pressure anisotropy, so subject to constraints imposed by the pressure-anisotropy-driven mirror and firehose instabilities and controlled by the local instantaneous plasma beta. The dynamics of such plasmas is dramatically different from a conventional MHD fluid. The plasma is expected to stay locally in a marginal state with respect to the instabilities, but how it does this is an open question. Two models of magnetic-field evolution are investigated. In the first, marginality is achieved via suppression of the rate of change of the field. In the second, the instabilities give rise to anomalous collisionality, reducing pressure anisotropy to marginal - at the same time decreasing viscosity and so increasing the turbulent rate of strain. Implications of these models are studied in a simplified 0D setting. In the first model, the field grows explosively but on a time scale that scales with initial beta, while in the second, dynamical field strength can be reached in one large-scale turbulence turn-over time regardless of the initial seed. Both models produce very intermittent fields. Both also suffer from strong constraints on their applicability: for typical cluster-core conditions, scale separation between the fluid motions and the microscale fluctuations breaks down at beta~10^5-10^4. At larger beta (weaker fields), a fully collisionless plasma dynamo theory is needed in order to justify the growth of the field from a tiny primordial seed. However, the models discussed here are appropriate for studying the structure of the currently observed field as well as large-scale dynamics and thermodynamics of the magnetized ICM or similarly dilute astrophysical plasmas.

Federico Mogavero; Alexander A. Schekochihin

2014-03-04T23:59:59.000Z

309

CALCULATION OF PULSED KICKER MAGNETIC FIELD ATTENUATION INSIDE BEAM CHAMBERS  

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

CALCULATION OF PULSED KICKER MAGNETIC FIELD ATTENUATION CALCULATION OF PULSED KICKER MAGNETIC FIELD ATTENUATION INSIDE BEAM CHAMBERS S. H. Kim January 8, 2001 1. Introduction and Summary The ceramic beam chambers in the sections of the kicker magnets for the beam injection and extraction in the Advanced Photon Source (APS) are made of alumina. The inner surface of the ceramic chamber is coated with a conductive paste. The choice of coating thickness is intended to reduce the shielding of the pulsed kicker magnetic field while containing the electromagnetic fields due to the beam bunches inside the chamber, and minimize the Ohmic heating due to the fields on the chamber [1]. The thin coating generally does not give a uniform surface resistivity for typical dimensions of the ceramic chambers in use. The chamber cross section is a circular or

310

Universality of critical magnetic field in holographic superconductor  

E-Print Network [OSTI]

Holographic superconductors with constant external magnetic field have been investigated by analytical matching method. It has been shown that the critical temperature and critical magnetic field can be calculated in non-zero temperature. Meissner effect has been observed in such superconductors. The relationship between normal entropy mode and superconductor with Bekenstein upper bound has been studied. Universal relation between black hole mass $ M$ and critical magnetic field $H_c$ has been proposed as $\\frac{H_c}{M^{2/3}}\\leq 0.60045$.

Davood Momeni; Ratbay Myrzakulov

2014-01-13T23:59:59.000Z

311

Heat pipes for use in a magnetic field  

DOE Patents [OSTI]

A heat pipe configuration for use in a magnetic field environment of a fusion reactor is disclosed. Heat pipes for operation in a magnetic field when liquid metal working fluids are used are optimized by flattening of the heat pipes having an unobstructed annulus which significantly reduces the adverse side region effect of the prior known cylindrically configured heat pipes. The flattened heat pipes operating in a magnetic field can remove 2--3 times the heat as a cylindrical heat pipe of the same cross sectional area. 4 figs.

Werner, R.W.; Hoffman, M.A.

1983-07-19T23:59:59.000Z

312

H{sub 3}{sup +} molecular ion in a magnetic field: Linear parallel configuration  

SciTech Connect (OSTI)

A detailed study of the ground state of the H{sub 3}{sup +} molecular ion in linear configuration, parallel to the magnetic field direction, and its low-lying {sigma}, {pi}, and {delta} states is carried out for magnetic fields B=0-4.414x10{sup 13} G in the Born-Oppenheimer approximation. The variational method is employed with a single trial function which includes electronic correlation in the form exp({gamma}r{sub 12}), where {gamma} is a variational parameter. It is shown that the quantum numbers of the state of the lowest total energy (ground state) depend on the magnetic field strength. The ground state evolves from the spin-singlet {sup 1}{sigma}{sub g} state for weak magnetic fields B(less-or-similar sign)5x10{sup 8} G to a weakly bound spin-triplet {sup 3}{sigma}{sub u} state for intermediate fields and, eventually, to a spin-triplet {sup 3}{pi}{sub u} state for 5x10{sup 10}(less-or-similar sign)B(less-or-similar sign)4.414x10{sup 13} G. Local stability of the linear parallel configuration with respect to possible small deviations is checked.

Turbiner, A. V.; Guevara, N. L.; Lopez Vieyra, J. C. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-543, 04510 Mexico, D.F. (Mexico)

2007-05-15T23:59:59.000Z

313

National High Magnetic Field Laboratory - Online Tour  

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

Audio Slideshows Arrow Online Tour Welcome to the Mag Lab's online tour. As we show you around the Florida State University branch of the world's biggest magnet lab, our scientists...

314

Dredging-induced near-field resuspended sediment concentrations and source strengths. Final report  

SciTech Connect (OSTI)

Dredging in riverine, lacustrine, and estuarine environments introduces bottom sediments into overlying waters because of imperfect entrainment and incomplete capture of sediments resuspended during the dredging process and the spillage or leakage of sediments during subsequent transportation and disposal of the dredged sediments. Resuspension of bottom sediments and resulting dispersal may pose water quality problems in waters near dredging operations. Interest in this issue increases when the sediment being dredged is highly contaminated. Resuspension of sediments by dredging is affected by dredge characteristics, dredge operating conditions, properties of bottom and suspended sediments, and site-specific conditions such as bottom topography, ambient current, and depth. This report summarizes field studies conducted by the U.S. Army Corps of Engineers to assess the suspended sediment concentrations in the water column in the vicinity of various dredge types. These concentration data are combined with conceptual models for resuspended sediment source strength geometries and velocity patterns to estimate sediment source strengths for cutterhead and clamshell dredges. Although unverified, these models provide a starting point for a more thorough analytical evaluation of the entire resuspension, transport, and deposition process.

Collins, M.A.

1995-08-01T23:59:59.000Z

315

Heat pulse propagation in chaotic 3-dimensional magnetic fields  

E-Print Network [OSTI]

Heat pulse propagation in $3$-D chaotic magnetic fields is studied by solving the parallel heat transport equation using a Lagrangian-Green's function (LG) method. The LG method provides an efficient and accurate technique that circumvents limitations of finite elements and finite difference methods. The main two problems addressed are: (i) The dependence of the radial transport on the magnetic field stochasticity (controlled by the amplitude of the perturbation, $\\epsilon$); and (ii) The role of reversed shear configurations on pulse propagation. In all the cases considered there are no magnetic flux surfaces. However, radial transport is observed to depend strongly on $\\epsilon$ due to the presence of high-order magnetic islands and Cantori that act as quasi-transport barriers that preclude the radial penetration of heat pulses within physically relevant time scale. The dependence of the magnetic field connection length, $\\ell_B$, on $\\epsilon$ is studied in detail. The decay rate of the temperature maximum...

del-Castillo-Negrete, D

2014-01-01T23:59:59.000Z

316

Intrinsic trapping of stochastic sheared magnetic field lines  

Science Journals Connector (OSTI)

The decorrelation trajectory method is applied to the diffusion of magnetic field lines in a perturbed sheared slab magnetic configuration. Some interesting decorrelation trajectories for several values of the magnetic Kubo number and of the shear parameter are exhibited. The asymmetry of the decorrelation trajectories appears in comparison with those obtained in the purely electrostatic case studied in earlier work. The running and asymptotic diffusion tensor components are calculated and displayed.

M. Negrea; I. Petrisor; R. Balescu

2004-10-14T23:59:59.000Z

317

Materials Physics Applications: The National High Magnetic Field Laboratory  

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

Search Search National High Magnetic Field Laboratory, NHMFL Home About Us Organization DIVISION Materials Physics and Applications Division GROUPS Superconductivity Technology Center Condensed Matter and Magnet Science Center for Integrated Nanotechnologies Sensors & Electrochemical Devices Materials Chemistry CONTACTS Group Leader Mike Hundley Director, NHMFL-PFF/Deputy Group Leader Chuck Mielke Head of Users Program Operations Jon Betts Professional Staff Assistant Julie T. Gallegos TA-03 Group Office TA-03, Building 0034, Room 101 Office Administrator Juanita Armijo TA-35 Group Office TA-35, Building 0127, Room C117 Office Administrator Angeline Willow 505-667-5032 National High Magnetic Field Laboratory, Pulsed Field Facility The Pulsed Field Facility at Los Alamos National Laboratory in Los Alamos, New Mexico, is one of three campuses of the National High Magnetic Field Laboratory (NHMFL), the other two being at Florida State University, Tallahassee (continuous fields, magnetic resonance, and general headquarters) and the University of Florida ,Gainesville(ultra-low temperatures at high magnetic fields). The NHMFL is sponsored primarily by the National Science Foundation, Division of Materials Research, with additional support from the State of Florida and the US Department of Energy.

318

CURRENT SHEETS FORMATION IN TANGLED CORONAL MAGNETIC FIELDS  

SciTech Connect (OSTI)

We investigate the dynamical evolution of magnetic fields in closed regions of solar and stellar coronae. To understand under which conditions current sheets form, we examine dissipative and ideal reduced magnetohydrodynamic models in Cartesian geometry, where two magnetic field components are present: the strong guide field B{sub 0}, extended along the axial direction, and the dynamical orthogonal field b. Magnetic field lines thread the system along the axial direction that spans the length L and are line-tied at the top and bottom plates. The magnetic field b initially has only large scales, with its gradient (current) length scale of the order of l{sub b}. We identify the magnetic intensity threshold b/B{sub 0} {approx} l{sub b}/L. For values of b below this threshold, field-line tension inhibits the formation of current sheets, while above the threshold they form quickly on fast ideal timescales. In the ideal case, above the magnetic threshold, we show that current sheets thickness decreases in time until it becomes smaller than the grid resolution, with the analyticity strip width {delta} decreasing at least exponentially, after which the simulations become underresolved.

Rappazzo, A. F. [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Parker, E. N., E-mail: franco.rappazzo@gmail.com, E-mail: parker@oddjob.uchicago.edu [Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)

2013-08-10T23:59:59.000Z

319

Quasi-two-dimensional excitons in finite magnetic fields  

Science Journals Connector (OSTI)

We present a theoretical and experimental investigation of the effects of a magnetic field on quasi-two-dimensional excitons. We calculate the internal structures and dispersion relations of spatially direct and indirect excitons in single and coupled quantum wells in a magnetic field perpendicular to the well plane. We find a sharp transition from a hydrogenlike exciton to a magnetoexciton with increasing the center-of-mass momentum at fixed weak field. At that transition the mean electron-hole separation increases sharply and becomes ?P/B?, where P is the magnetoexciton center-of-mass momentum and B? is the magnetic field perpendicular to the quantum well plane. The transition resembles a first-order phase transition. The magnetic-field–exciton momentum phase diagram describing the transition is constructed. We measure the magnetoexciton dispersion relations and effective masses in GaAs/Al0.33Ga0.67As coupled quantum wells using tilted magnetic fields. The calculated dispersion relations and effective masses are in agreement with the experimental data. We discuss the impact of magnetic field and sample geometry on the condition for observing exciton condensation.

Yu. E. Lozovik, I. V. Ovchinnikov, S. Yu. Volkov, L. V. Butov, and D. S. Chemla

2002-05-24T23:59:59.000Z

320

Bio-Med Variable Field MRI Project | Superconducting Magnet Division  

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

Bio-Med Variable Field MRI Project Bio-Med Variable Field MRI Project One of the Research and Development projects currently underway is the Bio-Med magnet. Destined for use within the solenoidal field of an MRI, it is designed for use where the subject, in this case a rat, must be tracked in order to obtain an image. Typical MRIs require the subject to remain stationary, and a rat will not normally oblige when it is awake. By moving the composite field (MRI Solenoid plus Bio-Med dipole) to track the rat, it is possible to allow the rat some freedom of motion, while still imaging the brain functions. For the rapid movement typical of a rat, the Bio-Med coil magnet must be capable of very rapid changes in field. Superconducting magnets are typically not designed to allow rapid field variations. To do so typically

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


321

Magnetic Moment of Vector Mesons in the Background Field Method  

E-Print Network [OSTI]

We report some results for the magnetic moments of vector mesons extracted from mass shifts in the presence of static external magnetic fields. The calculations are done on $24^4$ quenched lattices using standard Wilson actions, with $\\beta$=6.0 and pion mass down to 500 MeV. The results are compared to those from the form factor method.

Frank X. Lee; Scott Moerschbacher; Walter Wilcox

2007-10-11T23:59:59.000Z

322

New approaches to thermoelectric cooling effects in magnetic fields  

SciTech Connect (OSTI)

The authors review thermoelectric effects in a magnetic field at a phenomenological level. Discussions of the limiting performance and problems with its computation for both Peltier and Ettingshausen coolers are presented. New principles to guide the materials scientists are discussed for magnetic effects, and a brief review of the subtle measurement problems is presented.

Migliori, A.; Darling, T.W.; Freibert, F. [and others

1997-05-01T23:59:59.000Z

323

Design of Compound Solenoids to Produce Highly Homogeneous Magnetic Fields  

Science Journals Connector (OSTI)

......the size of the correcting coils. An elementary hill-climbing routine adjusts S to...which contains a magnetic field but no electric currents, V x H = 0, and a magnetic...to the length of wire used and to the resistance of that wire. Thus thefieldi/n,m......

S. T. LONEY

1966-06-01T23:59:59.000Z

324

Magnetic field exposure and arrythmic risk: evaluation in railway drivers  

Science Journals Connector (OSTI)

The environmental monitoring of ELF-EMF reported in the official documentation of the firm on examination was performed with the following: an isotrope meter of static magnetic fields Metrolab ETM-1; an isotrope ...

L. Santangelo; M. Di Grazia; F. Liotti…

2005-05-01T23:59:59.000Z

325

EMDEX (Electric and Magnetic Field Digital EXposure) system manuals  

SciTech Connect (OSTI)

The EPRI Electric and Magnetic Field Digital EXposure (EMDEX) system consists of hardware and software for characterizing electric and magnetic field exposures. The EMDEX meter is a computer-based portable unit that samples, at a user-programmable rate, the three vector components of magnetic flux density, a measure of the average electric field acting on the torso of the wearer (if an optional sensor is worn) and a measure of rotational motion of the meter in the earth's magnetic field. Modules of the DATACALC software package are used to program the EMDEX, retrieve data at the end of a measurement session, analyze EMDEX data, and prepare tabular and graphical data summaries. The User Manual is designed to provide instruction on the use of the exposure system hardware and software. The Technical Reference Manual provides additional, detailed descriptions of the hardware, software and methodologies used in the EMDEX system.

Not Available

1989-10-01T23:59:59.000Z

326

Background ELF Magnetic Fields in a Great Urban Area  

Science Journals Connector (OSTI)

Epidemiologic evidences about increasing of risk of tumoral pathology incidence for group of subjects exposed to ELF magnetic field levels greater than established thresholds (cut-off points) stress the import...

Giovanni d’Amore; Laura Anglesio…

1999-01-01T23:59:59.000Z

327

Advanced measurements and techniques in high magnetic fields  

SciTech Connect (OSTI)

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). High magnetic fields present a unique environment for studying the electronic structure of materials. Two classes of materials were chosen for experiments at the national high Magnetic Field Laboratory at Los Alamos: highly correlated electron systems and semiconductors. Magnetotransport and thermodynamic experiments were performed on the renormalized ground states of highly correlated electron systems (such as heavy fermion materials and Kondo insulators) in the presence of magnetic fields that are large enough to disrupt the many-body correlations. A variety of optical measurements in high magnetic fields were performed on semiconductor heterostructures including GaAs/AlGaAs single heterojunctions (HEMT structure), coupled double quantum wells (CDQW), asymmetric coupled double quantum wells (ACDQW), multiple quantum wells and a CdTe single crystal thin film.

Campbell, L.J.; Rickel, D.G. [Los Alamos National Lab., NM (United States); Lacerda, A.H. [Florida State Univ., Tallahassee, FL (United States); Kim, Y. [Northeastern Univ., Boston, MA (United States)

1997-07-01T23:59:59.000Z

328

alternating magnetic fields: Topics by E-print Network  

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

attention on recent progresses. Massimo Giovannini 2006-12-14 32 Cosmological Magnetic Fields vs. CMB Astrophysics (arXiv) Summary: I present a short review of the effects of a...

329

National High Magnetic Field Laboratory Slideshow: How to Make...  

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

easy, fun and most can be done with stuff you have around the house. Compasses in Magnetic Fields Experiment with the compass in this tutorial to see how it responds to...

330

MagLab - Magnetic Field of a Solenoid Tutorial  

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

Magnetic Field of a Solenoid This is a Java tutorial, which requires that you have Java, a free software, installed on your computer. It works best if you have the latest version...

331

National High Magnetic Field Laboratory: Museum of Electricity...  

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

of the composition of light. Light, of course, is a form of energy. A magnetic field changes the behavior of light - a phenomenon known as the Zeeman effect. The Zeeman...

332

National High Magnetic Field Laboratory - Flux: Volume 3, Issue...  

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

not Stephanie Law, who was practially an old-timer when she arrived at the Mag Lab. gauss lines Pregnancy to pacemakers: safety around high magnetic fields First things first......

333

The representation of magnetic field lines from magnetograph data  

Science Journals Connector (OSTI)

Several methods currently used to extrapolate the structure of the solar magnetic field from surface measurements are examined and compared. In particular, the differences between the methods of Schmidt for po...

Randolph H. Levine

1975-10-01T23:59:59.000Z

334

Port hole perturbations to the magnetic field in MST  

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

095002 (17pp) doi:10.10880741-3335529095002 Port hole perturbations to the magnetic field in MST P J Fimognari 1 , A F Almagri 1 , J K Anderson 1 , D R Demers 2 , J S Sarff 1 ,...

335

National High Magnetic Field Laboratory - Try This at Home  

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

fun and most can be done with stuff you have around the house. Create your own magnetic field lines, expose the iron in your cereal, or make an electromagnet from scratch Your...

336

National High Magnetic Field Laboratory - Ion Cyclotron Resonance...  

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

of Radial Ion Motion in RF-Only Multipole Ion Guides Immersed in a Strong Magnetic Field Gradient, J. Am. Soc. Mass Spectr., 22, 591-601 (2011) 2 Blakney, G.T.; Hendrickson,...

337

Science in High Magnetic Fields: What Could Be Learned?  

Science Journals Connector (OSTI)

High magnetic fields are one of the most powerful tools available to scientists for the study, modification and control of matter. This includes the knowledge on correlations effects, interaction mechanisms, s...

G. Martinez

2003-10-01T23:59:59.000Z

338

Magnetic Fields of the Satellites of Jupiter and Saturn  

Science Journals Connector (OSTI)

This paper reviews the present state of knowledge about the magnetic fields and the plasma interactions associated with the major satellites of Jupiter and Saturn. As revealed by the data from a number of spac...

Xianzhe Jia; Margaret G. Kivelson; Krishan K. Khurana…

2010-05-01T23:59:59.000Z

339

National High Magnetic Field Laboratory - Making a Compass Activity  

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

the south pole of the other. This is why compasses work on the Earth. The Earths magnetic field is strong enough to make the north pole of a very light compass needle align...

340

Solar nebula magnetic fields recorded in the Semarkona meteorite  

E-Print Network [OSTI]

Magnetic fields are proposed to have played a critical role in some of the most enigmatic processes of planetary formation by mediating the rapid accretion of disk material onto the central star and the formation of the ...

Fu, Roger Rennan

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


341

National High Magnetic Field Laboratory: Museum of Electricity...  

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

it lacked sophistication, he was able to use the model to formulate his own law of magnetism. Magnetometers are used in many different fields; they are used in geophysics,...

342

Magnetic Fields in High-Density Stellar Matter  

E-Print Network [OSTI]

I briefly review some aspects of the effect of magnetic fields in the high density regime relevant to neutron stars, focusing mainly on compact star structure and composition, superconductivity, combustion processes, and gamma ray bursts.

German Lugones

2005-04-20T23:59:59.000Z

343

Neutron in a Strong Magnetic Field: Finite Volume Effects  

E-Print Network [OSTI]

We investigate the neutron's response to magnetic fields on a torus with the aid of chiral perturbation theory, and expose effects from non-vanishing holonomies. The determination of such effects necessitates non-perturbative treatment of the magnetic field; and, to this end, a strong-field power counting is employed. Using a novel coordinate-space method, we find the neutron propagates in a coordinate-dependent effective potential that we obtain by integrating out charged pions winding around the torus. Knowledge of these finite volume effects will aid in the extraction of neutron properties from lattice QCD computations in external magnetic fields. In particular, we obtain finite volume corrections to the neutron magnetic moment and magnetic polarizability. These quantities have not been computed correctly in the literature. In addition to effects from non-vanishing holonomies, finite volume corrections depend on the magnetic flux quantum through an Aharonov-Bohm effect. We make a number of observations that demonstrate the importance of non-perturbative effects from strong magnetic fields currently employed in lattice QCD calculations. These observations concern neutron physics in both finite and infinite volume.

Brian C. Tiburzi

2014-03-04T23:59:59.000Z

344

Parallel heat transport in integrable and chaotic magnetic fields  

SciTech Connect (OSTI)

The study of transport in magnetized plasmas is a problem of fundamental interest in controlled fusion, space plasmas, and astrophysics research. Three issues make this problem particularly challenging: (i) The extreme anisotropy between the parallel (i.e., along the magnetic field), {chi}{sub ||} , and the perpendicular, {chi}{sub Up-Tack }, conductivities ({chi}{sub ||} /{chi}{sub Up-Tack} may exceed 10{sup 10} in fusion plasmas); (ii) Nonlocal parallel transport in the limit of small collisionality; and (iii) Magnetic field lines chaos which in general complicates (and may preclude) the construction of magnetic field line coordinates. Motivated by these issues, we present a Lagrangian Green's function method to solve the local and non-local parallel transport equation applicable to integrable and chaotic magnetic fields in arbitrary geometry. The method avoids by construction the numerical pollution issues of grid-based algorithms. The potential of the approach is demonstrated with nontrivial applications to integrable (magnetic island), weakly chaotic (Devil's staircase), and fully chaotic magnetic field configurations. For the latter, numerical solutions of the parallel heat transport equation show that the effective radial transport, with local and non-local parallel closures, is non-diffusive, thus casting doubts on the applicability of quasilinear diffusion descriptions. General conditions for the existence of non-diffusive, multivalued flux-gradient relations in the temperature evolution are derived.

Castillo-Negrete, D. del; Chacon, L. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States)

2012-05-15T23:59:59.000Z

345

Parallel heat transport in integrable and chaotic magnetic fields  

SciTech Connect (OSTI)

The study of transport in magnetized plasmas is a problem of fundamental interest in controlled fusion, space plasmas, and astrophysics research. Three issues make this problem particularly chal- lenging: (i) The extreme anisotropy between the parallel (i.e., along the magnetic field), , and the perpendicular, , conductivities ( / may exceed 1010 in fusion plasmas); (ii) Magnetic field lines chaos which in general complicates (and may preclude) the construction of magnetic field line coordinates; and (iii) Nonlocal parallel transport in the limit of small collisionality. Motivated by these issues, we present a Lagrangian Green s function method to solve the local and non-local parallel transport equation applicable to integrable and chaotic magnetic fields in arbitrary geom- etry. The method avoids by construction the numerical pollution issues of grid-based algorithms. The potential of the approach is demonstrated with nontrivial applications to integrable (magnetic island chain), weakly chaotic (devil s staircase), and fully chaotic magnetic field configurations. For the latter, numerical solutions of the parallel heat transport equation show that the effective radial transport, with local and non-local closures, is non-diffusive, thus casting doubts on the appropriateness of the applicability of quasilinear diffusion descriptions. General conditions for the existence of non-diffusive, multivalued flux-gradient relations in the temperature evolution are derived.

Del-Castillo-Negrete, Diego B [ORNL; Chacon, Luis [ORNL

2012-01-01T23:59:59.000Z

346

Phase-field simulation of electric-field-induced in-plane magnetic domain switching in magnetic/ferroelectric layered heterostructures  

E-Print Network [OSTI]

Phase-field simulation of electric-field-induced in-plane magnetic domain switching in magnetic. Phys. Lett. 99, 182510 (2011) Quantum tunneling of the Bloch point in a magnetic film with strong uniaxial magnetic anisotropy Low Temp. Phys. 37, 690 (2011) Evolution of magnetic bubble domains

Chen, Long-Qing

347

A Possible Explanation of the Nighttime Variations of ELF Signal Strengths in Connecticut  

Science Journals Connector (OSTI)

Since September 1970, we have sporadically made farfield ELF horizontal magnetic field strength measurements in Connecticut. The transmission source for these 1.6...

P. R. Bannister

1974-01-01T23:59:59.000Z

348

Mon. Not. R. Astron. Soc. 317, 4554 (2000) Global structure of self-excited magnetic fields arising from the magnetic  

E-Print Network [OSTI]

for small scales. The outer surface of the shell is penetrated by magnetic field lines in spot-like regionsMon. Not. R. Astron. Soc. 317, 45±54 (2000) Global structure of self-excited magnetic fields July 5 A B S T R AC T The global structure of a self-excited magnetic field arising from the magnetic

Haase, Markus

349

Thermoelectric effects in organic conductors in a strong magnetic field  

SciTech Connect (OSTI)

The linear response of the electron system of a layered conductor to the temperature gradient in this system in a strong magnetic field is investigated theoretically. Thermoelectric emf is studied as a function of the magnitude and orientation of a strong external magnetic field; the experimental investigation of this function, combined with the study of the electric and thermal resistance, allows one to completely determine the structure of the energy spectrum of charge carriers.

Kirichenko, O. V.; Peschanskii, V. G. [National Academy of Sciences of Ukraine, Verkin Institute for Low Temperature Physics and Engineering (Ukraine)], E-mail: vpeschansky@ilt.kharkov.ua; Hasan, R. A. [Bir-Zeit University (Autonomy of Palestine) (Country Unknown)

2007-07-15T23:59:59.000Z

350

Zigzag nanoribbons in external electric and magnetic fields  

Science Journals Connector (OSTI)

We consider the Schrodinger operators on zigzag nanoribbons (tight-binding models) in external magnetic and electric fields. If these fields are absent, then the spectrum of the Schrodinger operator consists of two non-flat bands and one flat band (an eigenvalue with infinite multiplicity) between them. We describe all magnetic and electric fields for which the unperturbed flat band remains the flat band and when one splits into the small band of the continuous spectrum. Also we determine spectral asymptotics for small fields and solve inverse spectral problem.

Evgeny L. Korotyaev; Anton A. Kutsenko

2010-01-01T23:59:59.000Z

351

E-Print Network 3.0 - arbitrary magnetic field Sample Search...  

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

magnetic field Search Powered by Explorit Topic List Advanced Search Sample search results for: arbitrary magnetic field Page: << < 1 2 3 4 5 > >> 1 Progress In Electromagnetics...

352

E-Print Network 3.0 - axisymmetric magnetic field Sample Search...  

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

magnetic field Search Powered by Explorit Topic List Advanced Search Sample search results for: axisymmetric magnetic field Page: << < 1 2 3 4 5 > >> 1 Magnetohydrodynamics in...

353

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

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

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

354

Seeing the Invisible: Educating the Public on Planetary Magnetic Fields and How they Affect Atmospheres  

E-Print Network [OSTI]

Seeing the Invisible: Educating the Public on Planetary Magnetic Fields and How they Affect to visualize ­ invisible · But planetary magnetic field and charged particle environments (magnetospheres

Fillingim, Matthew

355

The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance  

E-Print Network [OSTI]

The Helioseismic and Magnetic Imager (HMI) began near-continuous full-disk solar measurements on 1 May 2010 from the Solar Dynamics Observatory (SDO). An automated processing pipeline keeps pace with observations to produce observable quantities, including the photospheric vector magnetic field, from sequences of filtergrams. The primary 720s observables were released in mid 2010, including Stokes polarization parameters measured at six wavelengths as well as intensity, Doppler velocity, and the line-of-sight magnetic field. More advanced products, including the full vector magnetic field, are now available. Automatically identified HMI Active Region Patches (HARPs) track the location and shape of magnetic regions throughout their lifetime. The vector field is computed using the Very Fast Inversion of the Stokes Vector (VFISV) code optimized for the HMI pipeline; the remaining 180 degree azimuth ambiguity is resolved with the Minimum Energy (ME0) code. The Milne-Eddington inversion is performed on all full-di...

Hoeksema, J Todd; Hayashi, Keiji; Sun, Xudong; Schou, Jesper; Couvidat, Sebastien; Norton, Aimee; Bobra, Monica; Centeno, Rebecca; Leka, K D; Barnes, Graham; Turmon, Michael J

2014-01-01T23:59:59.000Z

356

Neutrino magnetic moment in a magnetized plasma  

E-Print Network [OSTI]

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

N. V. Mikheev; E. N. Narynskaya

2010-11-08T23:59:59.000Z

357

Parallel heat flux and flow acceleration in open field line plasmas with magnetic trapping  

SciTech Connect (OSTI)

The magnetic field strength modulation in a tokamak scrape-off layer (SOL) provides both flux expansion next to the divertor plates and magnetic trapping in a large portion of the SOL. Previously, we have focused on a flux expander with long mean-free-path, motivated by the high temperature and low density edge anticipated for an absorbing boundary enabled by liquid lithium surfaces. Here, the effects of magnetic trapping and a marginal collisionality on parallel heat flux and parallel flow acceleration are examined. The various transport mechanisms are captured by kinetic simulations in a simple but representative mirror-expander geometry. The observed parallel flow acceleration is interpreted and elucidated with a modified Chew-Goldberger-Low model that retains temperature anisotropy and finite collisionality.

Guo, Zehua; Tang, Xian-Zhu; McDevitt, Chris [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2014-10-15T23:59:59.000Z

358

T Tauri stellar magnetic fields: He I measurements  

E-Print Network [OSTI]

We present measurements of the longitudinal magnetic field in the circumstellar environment of seven classical T Tauri stars. The measurements are based on high-resolution circular spectropolarimetry of the He I 5876 emission line, which is thought to form in accretion streams controlled by a stellar magnetosphere. We detect magnetic fields in BP Tau, DF Tau and DN Tau, and detect statistically significant fields in GM Aur and RW Aur A at one epoch but not at others. We detect no field for DG Tau and GG Tau, with the caveat that these objects were observed at one epoch only. Our measurements for BP Tau and DF Tau are consistent, both in terms of sign and magnitude, with previous studies, suggesting that the characteristics of T Tauri magnetospheres are persistent over several years. We observed the magnetic field of BP Tau to decline monotonically over three nights, and have detected a peak field of 4kG in this object, the highest magnetic field yet observed in a T Tauri star. We combine our observations with results from the literature in order to perform a statistical analysis of the magnetospheric fields in BP Tau and DF Tau. Assuming a dipolar field, we determine a polar field of ~3kG and a dipole offset of 40deg for BP Tau, while DF Tau's field is consistent with a polar field of ~-4.5kG and a dipole offset of 10deg. We conclude that many classical T Tauri stars have circumstellar magnetic fields that are both strong enough and sufficiently globally-ordered to sustain large-scale magnetospheric accretion flows.

Neil H. Symington; Tim J. Harries; Ryuichi Kurosawa; Tim Naylor

2005-01-20T23:59:59.000Z

359

2-3 High Field Magnetic Resonance Facility  

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

HFMRF Overview HFMRF Overview High Field Magnetic Resonance Facility A significant portion of research conducted in the High Field Magnetic Resonance Facility (HFMRF) focuses on developing a fundamental, molecular-level understanding of biochemi- cal and biological systems and their response to environmental effects. A secondary focus is in materials science and catalysis and the chemical mechanisms and processes that operate in these areas. Resident and matrixed research staff within this facility offer expertise in the areas of structural biology, solid-state materials characterization, and magnetic resonance imaging (MRI) techniques. Instrumentation & Capabilities NMR * 900-MHz NMR (operational in 2004) * 800-MHz NMR * 750-MHz NMR * 600-MHz NMR (2 systems)

360

Effects of the 9-T magnetic field on MRS photodiode  

SciTech Connect (OSTI)

The experimental results on the performance of the MRS (Metal/Resistor/Semiconductor) photodiode in the strong magnetic field of 9T, and the possible impact of the quench of the magnet at 9.5T on sensor's operation are reported. The measurement method used is being described. The results of the work agree with the expectations that the MRS photodiode is not exhibiting sensitivity to the magnetic field presence. This result is essential for the design of the future electron-positron linear collider detector.

Beznosko, D.; Blazey, G.; Dyshkant, A.; Rykalin, V.; /Northern Illinois U.

2005-10-01T23:59:59.000Z

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


361

MRS Photodiode, LED and extruded scintillator performance in magnetic field  

SciTech Connect (OSTI)

The experimental results on the performance of the MRS (Metal/Resistor/Semiconductor) photodiode in the strong magnetic field of 4.4T, and the possible impact of the quench of the magnet at 4.5T on sensor's operation are reported. In addition, the experimental results on the performance of the extruded scintillator and WLS fiber, and various LEDs in the magnetic fields of 1.8T and 2.3T respectively, are detailed. The measurement method used is being described.

Beznosko, D.; Blazey, G.; Dyshkant, A.; Francis, K.; Kubik, D.; Rykalin, V.; Zutshi, V.; /Northern Illinois U.

2005-05-01T23:59:59.000Z

362

The influence of the magnetic field on the performance of an active magnetic regenerator (AMR)  

E-Print Network [OSTI]

The influence of the time variation of the magnetic field, termed the magnetic field profile, on the performance of a magnetocaloric refrigeration device using the active magnetic regeneration (AMR) cycle is studied for a number of process parameters for both a parallel plate and packed bed regenerator using a numerical model. The cooling curve of the AMR is shown to be almost linear far from the Curie temperature of the magnetocaloric material. It is shown that a magnetic field profile that is 10% of the cycle time out of sync with the flow profile leads to a drop in both the maximum temperature span and the maximum cooling capacity of 20-40\\% for both parallel plate and packed bed regenerators. The maximum cooling capacity is shown to depend very weakly on the ramp rate of the magnetic field. Reducing the temporal width of the high field portion of the magnetic field profile by 10% leads to a drop in maximum temperature span and maximum cooling capacity of 5-20%. An increase of the magnetic field from 1 T t...

Bjørk, R

2014-01-01T23:59:59.000Z

363

Er3+-doped Nanoparticles for Optical Detection of Magnetic Field  

Science Journals Connector (OSTI)

In this work, we have studied an effect of magnetic field up to 50 T on emission spectrum of Er3+ in Er3+-doped nanoparticles prepared by chemical etching of the respective bulk nano-glass-ceramics template and found a unique strong effect of the magnetic field on the integral intensity of the 4S3/2?4I15/2 green emission line while integral intensities of other visible emission lines were only slightly affected. ... Figure 2. 4.2 K spectra of the 4S3/2?4I15/2 luminescence band of Er3+-doped nanoparticles in different pulsed magnetic fields (pulsed field flat plateau is about 5 ms); the intensity of luminescence decreases with applied field (a). ...

Victor K. Tikhomirov; Liviu F. Chibotaru; Damien Saurel; Patrick Gredin; Michel Mortier; Victor V. Moshchalkov

2009-01-07T23:59:59.000Z

364

Magnetic field dissipation in converging flows  

Science Journals Connector (OSTI)

......spatial distribution that mirrors that of the gas. This...i.e., several Schwarzschild radii) where the magnetic...turbulent distribution that mirrors that of the gas...radius of about 20 Schwarzschild radii. Our treatment...region, as far as 105 Schwarzschild radii, where the compact......

Fulvio Melia; Victor Kowalenko

2001-11-11T23:59:59.000Z

365

Tuning magnetic disorder in diluted magnetic semiconductors using high fields to 89 Tesla  

SciTech Connect (OSTI)

We describe recent and ongoing studies at the National High Magnetic Field Laboratory at Los Alamos using the new '100 Tesla Multi-Shot Magnet', which is presently delivering fields up to {approx}89 T during its commissioning. We discuss the first experiments performed in this magnet system, wherein the linewidth of low-temperature photoluminescence spectra was used to directly reveal the degree of magnetic alloy disorder 'seen' by excitons in single Zn{sub 0.80}Cd{sub 0.22}Mn{sub 0.08}Se quantum wells. The magnetic potential landscape in II-VI diluted magnetic semiconductors (DMS) is typically smoothed when the embedded Mn{sup 2+} spins align in an applied field. However, an important (but heretofore untested) prediction of current models of compositional disorder is that magnetic alloy fluctuations in many DMS compounds should increase again in very large magnetic fields approaching 100 T. We observed precisely this increase above {approx}70 T, in agreement with a simple model of magnetic alloy disorder.

Crooker, Scott A [Los Alamos National Laboratory; Samarth, Nitin [PENN STATE U

2008-01-01T23:59:59.000Z

366

Electromagnetic polarization in partially ionized plasmas with strong magnetic fields and neutron star atmosphere models  

E-Print Network [OSTI]

Polarizability tensor of a strongly magnetized plasma and the polarization vectors and opacities of normal electromagnetic waves are studied for the conditions typical of neutron star atmospheres, taking account of partial ionization effects. Vacuum polarization is also included using a new set of fitting formulae that are accurate for wide range of field strengths. The full account of the coupling of the quantum mechanical structure of the atoms to their center-of-mass motion across the magnetic field is shown to be crucial for the correct evaluation of the polarization properties and opacities of the plasma. The self-consistent treatment of the polarizability and absorption coefficients proves to be necessary if the ionization degree of the plasma is low, which can occur in the atmospheres of cool or ultramagnetized neutron stars. Atmosphere models and spectra are presented to illustrate the importance of such self-consistent treatment.

A. Y. Potekhin; Dong Lai; G. Chabrier; W. C. G. Ho

2004-05-20T23:59:59.000Z

367

Magnetic field exposure characterization during environmental field surveys for the EMF RAPID program  

SciTech Connect (OSTI)

The characteristics of magnetic fields in different environments are systematically collected under the RAPID Engineering Project {number_sign}3. Exposure to magnetic field is due to area sources and to local sources at exposure points. This paper presents only a summary of results concerning exposure to area sources. The data presented in this paper show that area fields differ significantly between sites of the same environments. This makes it difficult to characterize each environment type by a field value. Characteristics of the site, such as age and number of floors of the building, probably have a large effect on the magnetic field, independently on the specific use of the building. Magnetic field exposure at exposure points is likely to show a greater dependence on the environment type.

Zaffanella, L.E. [Enertech Consultants, Lee, MA (United States)

1996-10-01T23:59:59.000Z

368

Atomic magnetic gradiometer for room temperature high sensitivity magnetic field detection  

DOE Patents [OSTI]

A laser-based atomic magnetometer (LBAM) apparatus measures magnetic fields, comprising: a plurality of polarization detector cells to detect magnetic fields; a laser source optically coupled to the polarization detector cells; and a signal detector that measures the laser source after being coupled to the polarization detector cells, which may be alkali cells. A single polarization cell may be used for nuclear magnetic resonance (NMR) by prepolarizing the nuclear spins of an analyte, encoding spectroscopic and/or spatial information, and detecting NMR signals from the analyte with a laser-based atomic magnetometer to form NMR spectra and/or magnetic resonance images (MRI). There is no need of a magnetic field or cryogenics in the detection step, as it is detected through the LBAM.

Xu,Shoujun (Berkeley, CA); Lowery, Thomas L. (Belmont, MA); Budker, Dmitry (El Cerrito, CA); Yashchuk, Valeriy V. (Richmond, CA); Wemmer, David E. (Berkeley, CA); Pines, Alexander (Berkeley, CA)

2009-08-11T23:59:59.000Z

369

MAGNETIC FIELDS IN THE HR DIAGRAM Jeffrey L. Linsky  

E-Print Network [OSTI]

MAGNETIC FIELDS IN THE HR DIAGRAM Jeffrey L. Linsky JILA/University of Colorado and NIST Solar IN SOLAR AND STELLAR ATMOSPHERES Heating Processes: MHD wave processes, rapid field annihilation processes has different properties and cell sizes than nor­ mal convection Wind: Alfv'en waves and other MHD

Linsky, Jeffrey L.

370

Self-field and magnetic-flux quantum mechanics  

E-Print Network [OSTI]

Self-field and quantized magnetic-flux are employed to generate the quantum numbers n, m, and l of atomic physics. Wave-particle duality is shown to be a natural outcome of having a particle and its self-field.

Paul Harris

2005-04-06T23:59:59.000Z

371

Measurement of megagauss magnetic fields in a plasma focus device  

Science Journals Connector (OSTI)

The magnetic field associated with the dense pinch in a plasma focus device has been measured from the Zeeman splitting of the Cv, 2s-2p emission. Values of the order of 1 MG are derived, in agreement with pressure balance between the self-field due to currents in the pinch and the kinetic pressure of the plasma.

N. J. Peacock and B. A. Norton

1975-06-01T23:59:59.000Z

372

DOES MAGNETIC-FIELD-ROTATION MISALIGNMENT SOLVE THE MAGNETIC BRAKING CATASTROPHE IN PROTOSTELLAR DISK FORMATION?  

SciTech Connect (OSTI)

Stars form in dense cores of molecular clouds that are observed to be significantly magnetized. In the simplest case of a laminar (non-turbulent) core with the magnetic field aligned with the rotation axis, both analytic considerations and numerical simulations have shown that the formation of a large, 10{sup 2} AU scale, rotationally supported protostellar disk is suppressed by magnetic braking in the ideal MHD limit for a realistic level of core magnetization. This theoretical difficulty in forming protostellar disks is termed the ''magnetic braking catastrophe''. A possible resolution to this problem, proposed by Hennebelle and Ciardi and Joos et al., is that misalignment between the magnetic field and rotation axis may weaken the magnetic braking enough to enable disk formation. We evaluate this possibility quantitatively through numerical simulations. We confirm the basic result of Joos et al. that the misalignment is indeed conducive to disk formation. In relatively weakly magnetized cores with dimensionless mass-to-flux ratio {approx}> 4, it enabled the formation of rotationally supported disks that would otherwise be suppressed if the magnetic field and rotation axis are aligned. For more strongly magnetized cores, disk formation remains suppressed, however, even for the maximum tilt angle of 90 Degree-Sign . If dense cores are as strongly magnetized as indicated by OH Zeeman observations (with a mean dimensionless mass-to-flux ratio {approx}2), it would be difficult for the misalignment alone to enable disk formation in the majority of them. We conclude that, while beneficial to disk formation, especially for the relatively weak field case, misalignment does not completely solve the problem of catastrophic magnetic braking in general.

Li Zhiyun [Astronomy Department, University of Virginia, Charlottesville, VA (United States); Krasnopolsky, Ruben; Shang, Hsien [Academia Sinica, Theoretical Institute for Advanced Research in Astrophysics, Taipei, Taiwan (China)

2013-09-01T23:59:59.000Z

373

Treating Cancer with Strong Magnetic Fields and Ultrasound  

E-Print Network [OSTI]

It is proposed to treat cancer by the combination of a strong magnetic field with intense ultrasound. At the low electrical conductivity of tissue the magnetic field is not frozen into the tissue, and oscillates against the tissue which is brought into rapid oscillation by the ultrasound. As a result, a rapidly oscillating electric field is induced in the tissue, strong enough to disrupt cancer cell replication. Unlike radio frequency waves, which have been proposed for this purpose, ultrasound can be easily focused onto the regions to be treated. This method has the potential for the complete eradication of the tumor.

Dr. Friedwardt Winterberg

2009-06-03T23:59:59.000Z

374

Reconnection and the Ideal Evolution of Magnetic Fields  

Science Journals Connector (OSTI)

A magnetic evolution is ideal if it is consistent with the field being embedded in a perfectly conducting fluid. Faraday's law implies the evolution is ideal when the parallel component of the electric field is the derivative of a scalar potential, a condition that generically holds in any local region of space. Reconnection requires the non-existence of such a potential. In systems with two periodic directions, non-existence focuses reconnection onto the surfaces in which the magnetic field lines close on themselves, the rational surfaces. This rational surface effect does not arise in astrophysics but does appear in periodic simulation codes. Effects that could give astrophysical reconnection are discussed.

Allen H. Boozer

2002-05-13T23:59:59.000Z

375

Electronic properties of graphite in tilted magnetic fields  

SciTech Connect (OSTI)

The minimal nearest-neighbor tight-binding model with the Peierls substitution is employed to describe the electronic structure of Bernal-stacked graphite subject to tilted magnetic fields. We show that while the presence of the in-plane component of the magnetic field has a negligible effect on the Landau level structure at the K point of the graphite Brillouin zone, at the H point it leads to the experimentally observable splitting of Landau levels which grows approximately linearly with the in-plane field intensity.

Goncharuk, Nataliya A.; Smr?ka, Ludvík [Institute of Physics, Academy of Science of the Czech Republic, v. v. i., Cukrovarnická 10, 162 53 Praha 6 (Czech Republic)

2014-05-15T23:59:59.000Z

376

Electron Heat Transport Measured in a Stochastic Magnetic Field T. M. Biewer,* C. B. Forest,  

E-Print Network [OSTI]

where magnetic islands overlap and field lines are stochastic. The measurements show that (1 magnetic flux surfaces. When flux surfaces exist, magnetic field lines and hence particle orbits are small, the magnetic field lines break into chains of magnetic islands at mode-rational sur- faces where

Biewer, Theodore

377

Nuclear magnetic resonances in weak fields  

E-Print Network [OSTI]

first choax@ation of nuclear resonances in weak f le). de was sade by k 0, S~ in fiel4u of 6 and lg gauss using a sanple siue of. 1 liter, The nagnetic fields were produced in a solenoi4 pou?x?d by a bazdz of lead storage batteriesx an4 the resonances..., Tbe poser was pxovided for the static nagnetic field by a bank of 20 lead storage cells connected in ssriesi The current was a+usted to the desired value with a variable xesistanoe which was connected in sex'ies with the solenoid. Qm source of field...

Mitchell, Richard Warren

2012-06-07T23:59:59.000Z

378

Magnetic anisotropy in Fe-25Cr-12Co-1Si alloy induced by external magnetic field  

E-Print Network [OSTI]

Magnetic anisotropy in Fe-25Cr-12Co-1Si alloy induced by external magnetic field ZHEN Liang( )1 of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China; 2. Department. Curriculum in Applied and Materials Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC

Qin, Lu-Chang

379

MAGNETIC POWER SPECTRA DERIVED FROM GROUND AND SPACE MEASUREMENTS OF THE SOLAR MAGNETIC FIELDS  

E-Print Network [OSTI]

of gas about in the photosphere, and will evidently act in the same way upon a magnetic line of force motion is by investigating the nature of the photospheric magnetic fields in terms Solar Physics 201: 225 with an energy cascade of turbulent motions. In the turbulent fluid motion, the kinetic energy cascades from

380

Influence of the Earth's magnetic field on large area photomultipliers  

SciTech Connect (OSTI)

The influence of the Earth's magnetic field on large area photomultipliers proposed for a future deep sea neutrino telescope was studied under the EU-funded KM3NeT design study. The aims were to evaluate variations in PMT performance in the Earth's magnetic field and to decide whether the use of magnetic shielding is necessary. Measurements were performed on three Hamamatsu PMTs: two 8-inch R5912 types, one of these with super-bi-alkali photocathode, and a 10-inch R7081 type with a standard bi-alkali photocathode. The various characteristics of the PMTs were measured while varying the PMT orientations with respect to the Earth's magnetic field, both with and without a mu-metal cage as magnetic shield. In the 8-inch PMTs the impact of the magnetic field was found to be smaller than that on the 10-inch PMT. The increased quantum efficiency in the 8 super-bi-alkali PMT almost compensated its smaller detection surface compared to the 10' PMT. No significant effects were measured upon transit time and the fraction of spurious pulses. (authors)

Leonora, E.; Aiello, S. [INFN - National Inst. of Nuclear Physics, Section of Catania, CO Via Santa Sofia 64, 95123 Catania (Italy); Leotta, G. [Dept. of Physics and Astronomy of Catania, CO Via Santa Sofia 64, 95123 Catania (Italy)

2011-07-01T23:59:59.000Z

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


381

Potential formation in a collisionless plasma produced in an open magnetic field in presence of volume negative ion source  

SciTech Connect (OSTI)

The electric potential near a wall for a multi-species plasma with volume produced negative ions in presence of axially varying magnetic field is studied following an analytical-numerical approach. A constant negative ion source is assumed throughout the plasma volume, along with finite temperature positive ions and Boltzmann electrons. The particles are assumed to be guided by an open magnetic field that has its maximum at the centre, and field strength decreasing towards the walls. The one dimensional (1D) Poisson equation is derived using an analytical approach, and then solved numerically to study the potential profiles. Effect of (a) negative ion production rate, (b) magnetic field profile, and (c) negative ion temperature on the potential profile has been investigated. A potential peak appears near the wall when the negative ion temperature and density are sufficiently high. Also, the presence of negative ions further decreases the potential in the plasma region for a finite Debye Length (?{sub D})

Phukan, Ananya, E-mail: ananya.phukan26@gmail.com; Goswami, K. S.; Bhuyan, P. J. [Centre of Plasma Physics, Institute for Plasma Research Sonapur, Kamrup (M), Assam 782402 (India)

2014-08-15T23:59:59.000Z

382

Kolmogorov-Sinai entropy in field line diffusion by anisotropic magnetic turbulence  

E-Print Network [OSTI]

The Kolmogorov-Sinai (KS) entropy in turbulent diffusion of magnetic field lines is analyzed on the basis of a numerical simulation model and theoretical investigations. In the parameter range of strongly anisotropic magnetic turbulence the KS entropy is shown to deviate considerably from the earlier predicted scaling relations [Rev. Mod. Phys. {\\bf 64}, 961 (1992)]. In particular, a slowing down logarithmic behavior versus the so-called Kubo number $R\\gg 1$ ($R = (\\delta B / B_0) (\\xi_\\| / \\xi_\\bot)$, where $\\delta B / B_0$ is the ratio of the rms magnetic fluctuation field to the magnetic field strength, and $\\xi_\\bot$ and $\\xi_\\|$ are the correlation lengths in respective dimensions) is found instead of a power-law dependence. These discrepancies are explained from general principles of Hamiltonian dynamics. We discuss the implication of Hamiltonian properties in governing the paradigmatic "percolation" transport, characterized by $R\\to\\infty$, associating it with the concept of pseudochaos (random non-chaotic dynamics with zero Lyapunov exponents). Applications of this study pertain to both fusion and astrophysical plasma and by mathematical analogy to problems outside the plasma physics. This research article is dedicated to the memory of Professor George M. Zaslavsky

Alexander V. Milovanov; Rehab Bitane; Gaetano Zimbardo

2009-04-23T23:59:59.000Z

383

Search for the magnetic field of the O7.5 III star xi Persei  

E-Print Network [OSTI]

Cyclical wind variability is an ubiquitous but as yet unexplained feature among OB stars. The O7.5 III(n)((f)) star xi Persei is the brightest representative of this class on the Northern hemisphere. As its prominent cyclical wind properties vary on a rotational time scale (2 or 4 days) the star has been already for a long time a serious magnetic candidate. As the cause of this enigmatic behavior non-radial pulsations and/or a surface magnetic field are suggested. We present a preliminary report on our attempts to detect a magnetic field in this star with high-resolution measurements obtained with the spectropolarimeter Narval at TBL, France during 2 observing runs of 5 nights in 2006 and 5 nights in 2007. Only upper limits could be obtained, even with the longest possible exposure times. If the star hosts a magnetic field, its surface strength should be less than about 300 G. This would still be enough to disturb the stellar wind significantly. From our new data it seems that the amplitude of the known non-r...

Henrichs, H F; de Jong, J A; Kaper, L; Donati, J F; Catala, C

2008-01-01T23:59:59.000Z

384

National High Magnetic Field Laboratory: Metallic Superlattices  

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

Many years would pass, however, before thin films became a major focus in the field of physics. The introduction of computers and the search for practical methods of data storage...

385

National High Magnetic Field Laboratory - Applied Superconductivity...  

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

the coupling between the gaps, and whether this produces new properties when quantized field lines move along grain boundaries or when MgB2 is exposed to microwave radiation. The...

386

Simulations of magnetic field gradients due to micro-magnets on a triple quantum dot circuit  

SciTech Connect (OSTI)

To quantify the effects of local magnetic fields on triple quantum dots, the Heisenberg Hamiltonian has been diagonalized for three electrons coupled via the exchange interaction. In particular, we have investigated different geometries of micro-magnets located on top of the triple dot in order to optimize the field gradient characteristics. In this paper, we focus on two geometries which are candidates for an addressable EDSR triple quantum dot device.

Poulin-Lamarre, G. [National Research Council of Canada, Ottawa, On., Canada, K1A-0R6 and Département de physique, Université de Sherbrooke, Sherbrooke, Qc. J1K-2R1 (Canada); Bureau-Oxton, C. [Département de physique, Université de Sherbrooke, Sherbrooke, Qc. J1K-2R1 (Canada); Kam, A. [National Research Council of Canada, Ottawa, On. K1A-0R6 (Canada); Zawadzki, P.; Aers, G. [National Research Council of Canada, Ottawa, On. K1A-0R6 (Canada); Studenikin, S. [National Research Council of Canada, Ottawa, On.K1A-0R6 (Canada); Pioro-Ladrière, M. [Département de physique, Université de Sherbrooke, Sherbrooke, Qc. J1K-2R1 (Canada); Sachrajda, A. S. [National Research Council of Canada, Ottawa, On., Canada, K1A-0R6 and Département de physique, Université de Sherbrooke, Sherbrooke, Qc. J1K-2R1 (Canada)

2013-12-04T23:59:59.000Z

387

Neutrino transition magnetic moments and the solar magnetic field on the light of the Kamland evidence  

E-Print Network [OSTI]

We present here a recopilation of recent results about the possibility of detecting solar electron antineutrinos produced by solar core and convective magnetic fields. These antineutrinos are predicted by spin-flavor oscillations at a significant rate even if this mechanism is not the leading solution to the SNP. Using the recent Kamland results and assuming a concrete model for antineutrino production by spin-flavor precession in the convective zone based on chaotic magnetic fields,we obtain bounds on the flux of solar antineutrinos, on the average conversion neutrino-antineutrino probability and on intrinsic neutrino magnetic moment. In the most conservative case, $\\mu\\lsim 2.5\\times 10^{-11} \\mu_B$ (95% CL). When studying the effects of a core magnetic field, we find in the weak limit a scaling of the antineutrino probability with respect to the magnetic field profile in the sense that the same probability function can be reproduced by any profile with a suitable peak field value. In this way the solar electron antineutrino spectrum can be unambiguosly predicted. We use this scaling and the negative results indicated by the KamLAND experiment to obtain upper bounds on the solar electron antineutrino flux. We find that, for a wide family of magnetic field profiles in the sun interior, the antineutrino appearance probability is largely determined by the magnetic field intensity but not by its shape. Explicit limits on neutrino transition moments are also obtained consistent with the convective case. These limits are therefore largerly independent of the detailed structure of the magnetic field in the solar interior.

V. Antonelli; B. C. Chauhan; J. Pulido; E. Torrente-Lujan

2003-10-29T23:59:59.000Z

388

Vibrating H3+ in a Uniform Magnetic Field  

Science Journals Connector (OSTI)

Knowledge of how the rotation–vibrational states are affected by the interaction of the molecule with such a field would likely facilitate the detection of H3+ in the universe at locations with magnetic fields such as interstellar media. ... The contour lines clearly show the ridge at D3h configurations, R1 = R2. ... For arbitrary orientation of the field with respect to the line connecting the centers, the pertinent Schroedinger equation is solved by evaluating anal. ...

Héctor Medel Cobaxin; Alexander Alijah

2013-03-05T23:59:59.000Z

389

Energy confinement and magnetic field generation in the SSPX spheromaka)  

Science Journals Connector (OSTI)

The Sustained Spheromak Physics Experiment (SSPX) [Hooper et al. Nuclear Fusion39 863 (1999)] explores the physics of efficient magnetic field buildup and energy confinement both essential parts of advancing the spheromak concept. Extending the spheromak formation phase increases the efficiency of magnetic field generation with the maximum edge magnetic field for a given injector current ( B ? I ) from 0.65 T ? MA previously to 0.9 T ? MA . We have achieved the highest electron temperatures ( T e ) recorded for a spheromak with T e > 500 eV toroidalmagnetic field ? 1 T and toroidal current ( ? 1 MA ) [Wood et al. “Improved magnetic field generation efficiency and higher temperaturespheromakplasmas ” Phys. Rev. Lett. (submitted)]. Extending the sustainment phase to > 8 ms extends the period of low magnetic fluctuations ( input power and dominantly collisional majority ion heating. The evolution of electron temperature shows a distinct and robust feature of spheromak formation: A hollow-to-peaked T e ( r ) associated with q ? 1 ? 2 .

B. Hudson; R. D. Wood; H. S. McLean; E. B. Hooper; D. N. Hill; J. Jayakumar; J. Moller; D. Montez; C. A. Romero-Talamás; T. A. Casper; J. A. Johnson III; L. L. LoDestro; E. Mezonlin; L. D. Pearlstein

2008-01-01T23:59:59.000Z

390

Generation of large-scale magnetic fields, non-Gaussianity, and primordial gravitational waves in inflationary cosmology  

E-Print Network [OSTI]

The generation of large-scale magnetic fields in inflationary cosmology is explored, in particular, in a kind of moduli inflation motivated by racetrack inflation in the context of the Type IIB string theory. In this model, the conformal invariance of the hypercharge electromagnetic fields is broken thanks to the coupling of both the scalar and pseudoscalar fields to the hypercharge electromagnetic fields. The following three cosmological observable quantities are first evaluated: The current magnetic field strength on the Hubble horizon scale, which is much smaller than the upper limit from the back reaction problem, the local non-Gaussianity of the curvature perturbations due to the existence of the massive gauge fields, and the tensor-to-scalar ratio. It is explicitly demonstrated that the resultant values of the local non-Gaussianity and the tensor-to-scalar ratio are consistent with the Planck data.

Bamba, Kazuharu

2014-01-01T23:59:59.000Z

391

The Solar Magnetic Field as a Coronal Hole Extension Forms: Effects of Magnetic Helicity and Boundary Conditions  

Science Journals Connector (OSTI)

An analytical solution is presented for linear force fields within a spherical shell, representing the solar corona. Allowing for a global magnetic helicity, we find magnetic fields over the entire corona with...

J. R. Clegg; B. J. I. Bromage; P. K. Browning

392

Magnetic-field generation and electron acceleration in relativistic laser channel  

E-Print Network [OSTI]

Magnetic-field generation and electron acceleration in relativistic laser channel I. Yu. Kostyukov itself as a strong axial magnetic field inverse Faraday effect . The magnitude of this magnetic field is calculated and related to the amount of the absorbed energy. Absorbed energy and generated magnetic field

393

Asymmetric magnetic reconnection in the presence of a guide field P. L. Pritchett1  

E-Print Network [OSTI]

to the magnetic field and particle outflows along the field lines. Such a symmetric treatment of the diffusionAsymmetric magnetic reconnection in the presence of a guide field P. L. Pritchett1 and F. S. Mozer2] The properties of asymmetric magnetic reconnection in the presence of a guide magnetic field are investigated

California at Berkeley, University of

394

Memorandum Approval of a Permanenet Variance Regarding Static Magnetic Fields at Brookhaven National Laboratory (Variance 1021)  

Broader source: Energy.gov [DOE]

Approval of a Permanenet Variance Regarding Static Magnetic Fields at Brookhaven National Laboratory (Variance 1021)

395

Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields  

E-Print Network [OSTI]

When a micron-sized magnetizable particle is introduced into a suspension of nanosized magnetic particles, the nanoparticles accumulate around the microparticle and form thick anisotropic clouds extended in the direction of the applied magnetic field. This phenomenon promotes colloidal stabilization of bimodal magnetic suspensions and allows efficient magnetic separation of nanoparticles used in bioanalysis and water purification. In the present work, size and shape of nanoparticle clouds under the simultaneous action of an external uniform magnetic field and the flow have been studied in details. In experiments, dilute suspension of iron oxide nanoclusters (of a mean diameter of 60 nm) was pushed through a thin slit channel with the nickel microspheres (of a mean diameter of 50$\\mu$m) attached to the channel wall. The behavior of nanocluster clouds was observed in the steady state using an optical microscope. In the presence of strong enough flow, the size of the clouds monotonically decreases with increasing flow speed in both longitudinal and transverse magnetic fields. This is qualitatively explained by enhancement of hydrodynamic forces washing the nanoclusters away from the clouds. In the longitudinal field, the flow induces asymmetry of the front and the back clouds. To explain the flow and the field effects on the clouds, we have developed a simple model based on the balance of the stresses and particle fluxes on the cloud surface. This model, applied to the case of the magnetic field parallel to the flow, captures reasonably well the flow effect on the size and shape of the cloud and reveals that the only dimensionless parameter governing the cloud size is the ratio of hydrodynamic-to-magnetic forces - the Mason number. At strong magnetic interactions considered in the present work (dipolar coupling parameter $\\alpha \\geq 2$), the Brownian motion seems not to affect the cloud behavior.

Cécilia Magnet; Pavel Kuzhir; Georges Bossis; Alain Meunier; Sebastien Nave; Andrey Zubarev; Claire Lomenech; Victor Bashtovoi

2014-04-14T23:59:59.000Z

396

Marine Magnetic Data Processing In Equatorial Regions Off Ghana  

Science Journals Connector (OSTI)

......equatorial region. The heading effect of the ship's magnetic field and strong...equatorial region. The heading effect of the ship's magnetic field and strong...anomaly interpretation. The effects of the ship's heading on the field strength......

S. K. Buchanan; R. A. Scrutton; R. A. Edwards; R. B. Whitmarsh

1996-04-01T23:59:59.000Z

397

The Cost of Superconducting Magnets as a Function of Stored Energy and Design Magnetic Induction Times the Field Volume  

SciTech Connect (OSTI)

By various theorems one can relate the capital cost of superconducting magnets to the magnetic energy stored within that magnet. This is particularly true for magnet where the cost is dominated by the structure needed to carry the magnetic forces. One can also relate the cost of the magnet to the product of the magnetic induction and the field volume. The relationship used to estimate the cost the magnet is a function of the type of magnet it is. This paper updates the cost functions given in two papers that were published in the early 1990 s. The costs (escalated to 2007 dollars) of large numbers of LTS magnets are plotted against stored energy and magnetic field time field volume. Escalated costs for magnets built since the early 1990 s are added to the plots.

Green, Mike; Green, M.A.; Strauss, B.P.

2007-08-27T23:59:59.000Z

398

Observation of Dirac Monopoles in a Synthetic Magnetic Field  

E-Print Network [OSTI]

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

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

2014-08-13T23:59:59.000Z

399

MAGNETIC FIELD STRUCTURES TRIGGERING SOLAR FLARES AND CORONAL MASS EJECTIONS  

SciTech Connect (OSTI)

Solar flares and coronal mass ejections, the most catastrophic eruptions in our solar system, have been known to affect terrestrial environments and infrastructure. However, because their triggering mechanism is still not sufficiently understood, our capacity to predict the occurrence of solar eruptions and to forecast space weather is substantially hindered. Even though various models have been proposed to determine the onset of solar eruptions, the types of magnetic structures capable of triggering these eruptions are still unclear. In this study, we solved this problem by systematically surveying the nonlinear dynamics caused by a wide variety of magnetic structures in terms of three-dimensional magnetohydrodynamic simulations. As a result, we determined that two different types of small magnetic structures favor the onset of solar eruptions. These structures, which should appear near the magnetic polarity inversion line (PIL), include magnetic fluxes reversed to the potential component or the nonpotential component of major field on the PIL. In addition, we analyzed two large flares, the X-class flare on 2006 December 13 and the M-class flare on 2011 February 13, using imaging data provided by the Hinode satellite, and we demonstrated that they conform to the simulation predictions. These results suggest that forecasting of solar eruptions is possible with sophisticated observation of a solar magnetic field, although the lead time must be limited by the timescale of changes in the small magnetic structures.

Kusano, K.; Bamba, Y.; Yamamoto, T. T. [Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601 (Japan); Iida, Y.; Toriumi, S. [Department of Earth and Planetary Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Asai, A., E-mail: kusano@nagoya-u.jp [Unit of Synergetic Studies for Space, Kyoto University, 17 Kitakazan Ohmine-cho, Yamashina-ku, Kyoto 607-8471 (Japan)

2012-11-20T23:59:59.000Z

400

Development of fast cooling pulsed magnets at the Wuhan National High Magnetic Field Center  

SciTech Connect (OSTI)

Pulsed magnets with fast cooling channels have been developed at the Wuhan National High Magnetic Field Center. Between the inner and outer sections of a coil wound with a continuous length of CuNb wire, G10 rods with cross section 4 mm × 5 mm were inserted as spacers around the entire circumference, parallel to the coil axis. The free space between adjacent rods is 6 mm. The liquid nitrogen flows freely in the channels between these rods, and in the direction perpendicular to the rods through grooves provided in the rods. For a typical 60 T pulsed magnetic field with pulse duration of 40 ms, the cooling time between subsequent pulses is reduced from 160 min to 35 min. Subsequently, the same technology was applied to a 50 T magnet with 300 ms pulse duration. The cooling time of this magnet was reduced from 480 min to 65 min.

Peng, Tao; Sun, Quqin; Zhao, Jianlong; Jiang, Fan; Li, Liang; Xu, Qiang [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan (China)] [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan (China); Herlach, Fritz [Department of Physics, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium)] [Department of Physics, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium)

2013-12-15T23:59:59.000Z

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


401

Magnetic Fields in Gamma-Ray Bursts: A Short Review  

E-Print Network [OSTI]

Magnetic fields play a crucial role in the physics of Gamma-Ray Bursts (GRBs). Strong observational evidence indicates that the observed afterglow and most likely the prompt emission arise from synchrotron emission. It is possible that Poynting flux plays an important or even dominant role in the relativistic outflow from the inner engine, but like in other astronomical relativistic jets this suggestion is controversial. Finally, it is likely that magnetic fields larger than $10^{15}$ G occur within GRBs' inner engines and contribute to the acceleration and collimation of the relativistic jets. I review here the GRB fireball model and discuss the role that magnetic fields play in its various components. I suggest that the early afterglow, that reflects the initial interaction of the relativistic jet with its surrounding matter is the best available tool to explore the nature of relativistic outflow in astronomical relativistic jets.

Tsvi Piran

2005-03-02T23:59:59.000Z

402

Mechanical Strength, Swelling and Weight Loss of Inorganic Fusion Magnet Insulation Systems Following Reactor Irradiation  

Science Journals Connector (OSTI)

Superconducting fusion magnets require a high electrical and mechanical ... were irradiated at ambient temperature in the TRIGA reactor (Vienna, Austria) up to neutron fluences...21, 1022 and 5x1022 m?2...(E>0.1 ...

K. Humer; P. Rosenkranz; H. W. Weber…

2000-01-01T23:59:59.000Z

403

Electric and magnetic field exposure associated with electric blankets  

SciTech Connect (OSTI)

electric blankets may be important contributors to the public's overall exposure to 60 Hz electric and magnetic fields (EMFs) since they are common appliances that are used close to the body for long periods of time. This report describes a series of experimental and computer analyses characterizing various aspects of EMF exposure from electric blankets in use prior to Fall 1990. Almost of electric blankets were found to use on/off controllers with cycle periods of minutes. Calculations of magnetic fields within the body show that, when blankets are heating, flux densities averaged over the whole body range from 15--33 mG during the on'' cycle with typical values of 22 mG. Duty cycles are predicted to vary widely from user-to-user, with typical values of perhaps 40%. Given typical blanket usage patterns, the long-term body-averaged magnetic field exposure from blankets is expected to be comparable to that form other EMF sources for a significant fraction of the blanket-using population. No significant differences were found between time-averaged magnetic field exposures from blankets with metal alloy and plastic polymer heating elements. Blankets with alloy and polymer heating elements did differ significantly in electric field exposure. Calculations show that the unperturbed field 5 cm above flat blankets range from 60--150 V/m for alloy heating cables and unperturbed field 5 cm above flat blankets range from 60--150 V/m for alloy heating cables and 10--40 V/m polymer cables. Starting in Fall 1990, electric blanket manufactures introduced new designs that produce much smaller magnetic fields. These are expected to replace the current in-use stock at a rate of 10--15% per year.

Florig, H.K.; Hoburg, J.F. (Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Engineering and Public Policy)

1991-12-01T23:59:59.000Z

404

The Hanle Effect as a Diagnostic of Magnetic Fields in Stellar Envelopes IV. Application to Polarized P Cygni Wind Lines  

E-Print Network [OSTI]

The Hanle effect has been proposed as a new diagnostic of circumstellar magnetic fields for early-type stars, for which it is sensitive to field strengths in the 1-300 G range. In this paper we compute the polarized P-Cygni line profiles that result from the Hanle effect. For modeling the polarization, we employ a variant of the ``last scattering approximation''. For cases in which the Sobolev optical depths are greater than unity, the emergent line intensity is assumed to be unpolarized; while for smaller optical depths, the Stokes source functions for the Hanle effect with optically thin line scattering are used. For a typical P Cygni line, the polarized emission forms in the outer wind, because the Sobolev optical depth is large at the inner wind. For low surface field strengths, weak P Cygni lines are needed to measure the circumstellar field. For high values of the surface fields, both the Zeeman and Hanle diagnostics can be used, with the Zeeman effect probing the photospheric magnetic fields, and the Hanle effect measuring the magnetic field in the wind flow. Polarized line profiles are calculated for a self-consistent structure of the flow and the magnetic geometry based on the WCFields model, which is applicable to slowly rotating stellar winds with magnetic fields drawn out by the gas flow. For surface fields of a few hundred Gauss, we find that the Hanle effect can produce line polarizations in the range of a few tenths of a percent up to about 2 percent.

R. Ignace; K. H. Nordsieck; J. P. Cassinelli

2004-03-17T23:59:59.000Z

405

Local CP-violation and electric charge separation by magnetic fields from lattice QCD  

E-Print Network [OSTI]

We study local CP-violation on the lattice by measuring the local correlation between the topological charge density and the electric dipole moment of quarks, induced by a constant external magnetic field. This correlator is found to increase linearly with the external field, with the coefficient of proportionality depending only weakly on temperature. Results are obtained on lattices with various spacings, and are extrapolated to the continuum limit after the renormalization of the observables is carried out. This renormalization utilizes the gradient flow for the quark and gluon fields. Our findings suggest that the strength of local CP-violation in QCD with physical quark masses is about an order of magnitude smaller than a model prediction based on nearly massless quarks in domains of constant gluon backgrounds with topological charge. We also show numerical evidence that the observed local CP-violation correlates with spatially extended electric dipole structures in the QCD vacuum.

G. S. Bali; F. Bruckmann; G. Endrodi; Z. Fodor; S. D. Katz; A. Schafer

2014-01-16T23:59:59.000Z

406

Utilizing Nitrogen Vacancy Centers to measure oscillating magnetic fields  

E-Print Network [OSTI]

We show how nitrogen vacancy (NV) centers can be used to determine the amplitude, phase and frequency of unknown weak monochromatic and multichromatic oscillating magnetic fields using only the periodic dynamical decoupling (PDD) and Carr-Purcell-Meiboom-Gill (CPMG) sequences. The effect of decoherence on the measurement of the magnetic field parameters is explicitly analyzed, and we take into account the fact that different pulse sequences suppress decoherence to different extents. Since the sensitivity increases with increasing sensing time while it decreases due to decoherence, we use the Fisher information matrix in order to optimize the number of pulses that should be used.

Adam Zaman Chaudhry

2014-04-11T23:59:59.000Z

407

Electric and Magnetic Fields (EMF) RAPID Engineering Program, Project 7: Development of Field Exposure Models  

SciTech Connect (OSTI)

The purpose of this project was to develop a conceptual model for estimating magnetic field (EMF) personal exposure (PE) of individuals or groups and construct a working model using existing data.

Bracken, T.D.; Rankin, R.F.; Wiley, J.A.

1999-05-01T23:59:59.000Z

408

Determining the exchange parameters of spin-1 metal-organic molecular magnets in pulsed magnetic fields  

SciTech Connect (OSTI)

We nave measured the high-field magnetization of a number of Ni-based metal-organic molecular magnets. These materials are self-assembly coordination polymers formed from transition metal ions and organic ligands. The chemistry of the compounds is versatile allowing many structures with different magnetic properties to be formed. These studies follow on from previous measurements of the Cu-based analogues in which we showed it was possible to extract the exchange parameters of low-dimensional magnets using pulsed magnetic fields. In our recent experiments we have investigated the compound (Ni(HF{sub 2})(pyz){sub 2})PF{sub 6}, where pyz = pyrazine, and the Ni-ions are linked in a quasi-two-dimensional (Q2D) square lattice via the pyrazine molecules, with the layers held together by HF{sub 2} ligands. We also investigated Ni(NCS){sub 2}(pyzdo){sub 2}, where pyzdo = pyrazine dioxide. The samples are grown at Eastern Washington University using techniques described elsewhere. Measurements are performed at the pulsed magnetic field laboratory in Los Alamos. The magnetization of powdered samples is determined using a compensated coil magnetometer in a 65 T short pulse magnet. Temperatures as low as 500 mK are achievable using a {sup 3}He cryostat. The main figure shows the magnetization of the spin-1 [Ni(HF{sub 2})(pyz){sub 2}]PF{sub 6} compound at 1.43 K. The magnetization rises slowly at first, achieving a rounded saturation whose midpoint is around 19 T. A small anomaly is also seen in the susceptibility at low fields ({approx}3 T), which might be attributed to a spin-flop transition. In contrast, the spin-1/2 [Cu(HF{sub 2})(pyz){sub 2}]PF{sub 6} measured previously has a saturation magnetization of 35.5 T and a strongly concave form of M(B) below this field. This latter compound was shown to be a good example of a Q2D Heisenberg antiferromagnet with the strong exchange coupling (J{sub 2D} = 12.4 K, J{sub {perpendicular}}/J{sub 2D} {approx} 10{sup -2}) directed along the Cu-pyz-Cu directions. The structure of the two compounds is similar, but in the case of the Cu-compound the Cu-Cu pathways are linear, whereas in the Ni-compound they are kinked. The pulsed-field data combined with information from temperature-dependent susceptibility, muon-spin rotation, electron-spin resonance and ligand-field calculations suggest that, far from being magnetically Q2D, the Ni-compound is fairly one-dimensional with the dominant exchange (J{sub 1D} = 3.1 K and J{sub {perpendicular}}/J{sub 1D} = 0.63) directed along the Ni-FHF-Ni direction. Ni(NCS){sub 2}(pyzdo){sub 2} was also investigated. Previous ultra-high field measurements using the 100 T magnet have shown that this compound has a saturation field close to 80 T. The purpose of the present studies is to map out the phase diagram of this material at mid-range fields. The data are shown in the inset to the figure. This continuing project probes the ability of organic ligands to mediate magnetic exchange, the link between structure, dimensionality and bulk magnetic properties, as well as the role of spin number in quantum magnets. Ultimately the investigations aim to determine to what extent it is possible to produce self-assembly molecular materials with tailor-made magnetic characteristics.

Mcdonald, Ross D [Los Alamos National Laboratory; Singleton, John [Los Alamos National Laboratory; Lancaster, Tom [OXFORD UNIV.; Goddard, Paul [OXFORD UNIV.; Manson, Jamie [EASTERN WASHINGTON UNIV.

2011-01-14T23:59:59.000Z

409

An IMAGE Satellite Guide to Exploring the Earth's Magnetic Field 1 An IMAGE Satellite Guide to Exploring the Earth's Magnetic Field 2  

E-Print Network [OSTI]

observed by the IMAGE, HENA instrument. Some representative magnetic field lines are shown in whiteAn IMAGE Satellite Guide to Exploring the Earth's Magnetic Field 1 #12;An IMAGE Satellite Guide to Exploring the Earth's Magnetic Field 2 Dr. James Burch IMAGE Principal Investigator Dr. William Taylor Dr

410

On collisional diffusion in a stochastic magnetic field  

SciTech Connect (OSTI)

The effect of particle collisions on the transport in a stochastic magnetic field in tokamaks is investigated. The model of resonant magnetic perturbations generated by external coils at the plasma edge is used for the stochastic magnetic field. The particle collisions are simulated by a random walk process along the magnetic field lines and the jumps across the field lines at the collision instants. The dependencies of the local diffusion coefficients on the mean free path ?{sub mfp}, the diffusion coefficients of field lines D{sub FL}, and the collisional diffusion coefficients, ?{sub ?} are studied. Based on these numerical data and the heuristic arguments, the empirical formula, D{sub r}=?{sub ?}+v{sub ||}D{sub FL}/(1+L{sub c}/?{sub mfp}), for the local diffusion coefficient is proposed, where L{sub c} is the characteristic length of order of the connection length l{sub c}=?qR{sub 0}, q is the safety factor, R{sub 0} is the major radius. The formula quite well describes the results of numerical simulations. In the limiting cases, the formula describes the Rechester-Rosenbluth and Laval scalings.

Abdullaev, S. S. [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung - Plasmaphysik, EURATOM Association, 52425 Jülich (Germany)] [Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung - Plasmaphysik, EURATOM Association, 52425 Jülich (Germany)

2013-08-15T23:59:59.000Z

411

Strongest non-destructive magnetic field: world record set at 100-tesla  

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

Strongest non-destructive magnetic field: world record set at Strongest non-destructive magnetic field: world record set at 100-tesla level Strongest non-destructive magnetic field: world record set at 100-tesla level National High Magnetic Field Laboratory magnet achieved a whopping 100.75 tesla-the 100-tesla level is roughly equivalent to 2 million times Earth's magnetic field. March 22, 2012 World record set at National High Magnetic Field Laboratory, Los Alamos In 2011, researchers at the National High Magnetic Field Laboratory set a new world record for the strongest nondestructive magnet field: 97.4 tesla. The feat positioned them to in March 2012 deliver a magnet capable of achieving the elusive 100-tesla goal, profoundly affecting a range of scientific investigations. Get Expertise Director, Pulsed Field Facility

412

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

E-Print Network [OSTI]

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

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

2010-03-09T23:59:59.000Z

413

Electron Plasmas in a Magnetic Mirror  

E-Print Network [OSTI]

scale with the magnetic field strength; the electrostatic potential varies along the field lines to make this density variation possible. Further, the plasma profile does not follow the magnetic field lines proportional to magnetic field. · Potential varies along field lines. · Outer plasma radius necks down more

Wurtele, Jonathan

414

THE CENTAURUS A ULTRAHIGH-ENERGY COSMIC-RAY EXCESS AND THE LOCAL EXTRAGALACTIC MAGNETIC FIELD  

SciTech Connect (OSTI)

The ultrahigh-energy cosmic-ray (UHECR) anisotropies discovered by the Pierre Auger Observatory provide the potential to finally address both the particle origins and properties of the nearby extragalactic magnetic field (EGMF). We examine the implications of the excess of {approx}10{sup 20} eV events around the nearby radio galaxy Centaurus A. We find that, if Cen A is the source of these cosmic rays, the angular distribution of events constrains the EGMF strength within several Mpc of the Milky Way to {approx}> 20 nG for an assumed primary proton composition. Our conclusions suggest that either the observed excess is a statistical anomaly or the local EGMF is stronger than conventionally thought. We discuss several implications, including UHECR scattering from more distant sources, time delays from transient sources, and the possibility of using magnetic lensing signatures to attain tighter constraints.

Yueksel, Hasan; Kronberg, Philipp P. [Theoretical Division, MS B285, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Stanev, Todor [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Kistler, Matthew D. [Lawrence Berkeley National Laboratory and Department of Physics, University of California, Berkeley, CA 94720 (United States)

2012-10-10T23:59:59.000Z

415

Ultra-low field nuclear magnetic resonance and magnetic resonance imaging to discriminate and identify materials  

DOE Patents [OSTI]

An ultra-low magnetic field NMR system can non-invasively examine containers. Database matching techniques can then identify hazardous materials within the containers. Ultra-low field NMR systems are ideal for this purpose because they do not require large powerful magnets and because they can examine materials enclosed in conductive shells such as lead shells. The NMR examination technique can be combined with ultra-low field NMR imaging, where an NMR image is obtained and analyzed to identify target volumes. Spatial sensitivity encoding can also be used to identify target volumes. After the target volumes are identified the NMR measurement technique can be used to identify their contents.

Kraus, Robert H. (Los Alamos, NM); Matlashov, Andrei N. (Los Alamos, NM); Espy, Michelle A. (Los Alamos, NM); Volegov, Petr L. (Los Alamos, NM)

2010-03-30T23:59:59.000Z

416

Heat pulse propagation in chaotic 3-dimensional magnetic fields  

E-Print Network [OSTI]

Heat pulse propagation in $3$-D chaotic magnetic fields is studied by solving the parallel heat transport equation using a Lagrangian-Green's function (LG) method. The LG method provides an efficient and accurate technique that circumvents limitations of finite elements and finite difference methods. The main two problems addressed are: (i) The dependence of the radial transport on the magnetic field stochasticity (controlled by the amplitude of the perturbation, $\\epsilon$); and (ii) The role of reversed shear configurations on pulse propagation. In all the cases considered there are no magnetic flux surfaces. However, radial transport is observed to depend strongly on $\\epsilon$ due to the presence of high-order magnetic islands and Cantori that act as quasi-transport barriers that preclude the radial penetration of heat pulses within physically relevant time scale. The dependence of the magnetic field connection length, $\\ell_B$, on $\\epsilon$ is studied in detail. The decay rate of the temperature maximum, $\\langle T \\rangle_{max}(t)$, the time delay of the temperature response as function of the radius, $\\tau$, and the radial heat flux $\\langle {{\\bf q}\\cdot {\\hat e}_\\psi} \\rangle$, are also studied as functions of the magnetic field stochasticity and $\\ell_B$. In all cases, the scaling of $\\langle T \\rangle_{max}$ with $t$ transitions from sub-diffusive, $\\langle T \\rangle_{max} \\sim t^{-1/4}$, at short times ($\\chi_\\parallel t 10^5$). A strong dependence on $\\epsilon$ is also observed on $\\tau$ and $\\langle {{\\bf q}\\cdot {\\hat e}_\\psi} \\rangle$. The radial propagation of pulses in fully chaotic fields considerably slows down in the shear reversal region and, as a result, $\\tau$, in reversed shear configurations is an order of magnitude longer than the one in monotonic $q$-profiles.

D. del-Castillo-Negrete; D. Blazevski

2014-09-10T23:59:59.000Z

417

Kinetic models of current sheets with a sheared magnetic field  

SciTech Connect (OSTI)

Thin current sheets, whose existence in the Earth's magnetotail is confirmed by numerous spacecraft measurements, are studied analytically and numerically. The thickness of such sheets is on the order of the ion Larmor radius, and the normal component of the magnetic field (B{sub z}) in the sheet is almost constant, while the tangential (B{sub x}) and shear (B{sub y}) components depend on the transverse coordinate z. The current density in the sheet also has two self-consistent components (j{sub x} and j{sub y}, respectively), and the magnetic field lines are deformed and do not lie in a single plane. To study such quasi-one-dimensional current configurations, two kinetic models are used, in particular, a numerical model based on the particle-in-cell method and an analytical model. The calculated results show that two different modes of the self-consistent shear magnetic field B{sub y} and, accordingly, two thin current sheet configurations can exist for the same input parameters. For the mode with an antisymmetric z profile of the B{sub y} component, the magnetic field lines within the sheet are twisted, whereas the profiles of the plasma density, current density component j{sub y}, and magnetic field component B{sub x} differ slightly from those in the case of a shearless magnetic field (B{sub y} = 0). For the symmetric B{sub y} mode, the magnetic field lines lie in a curved surface. In this case, the plasma density in the sheet varies slightly and the current sheet is two times thicker. Analysis of the dependence of the current sheet structure on the flow anisotropy shows that the sheet thickness decreases significantly with decreasing ratio between the thermal and drift plasma velocities, which is caused by the dynamics of quasi-adiabatic ions. It is shown that the results of the analytical and numerical models are in good agreement. The problems of application of these models to describe current sheets at the magnetopause and near magnetic reconnection regions are discussed.

Mingalev, O. V.; Mingalev, I. V.; Mel'nik, M. N. [Russian Academy of Sciences, Polar Geophysical Institute, Cola Science Center (Russian Federation); Artemyev, A. V.; Malova, H. V.; Popov, V. Yu. [Russian Academy of Sciences, Space Research Institute (Russian Federation); Chao, Shen [Chinese Academy of Sciences, Center for Space Science and Applied Research (China); Zelenyi, L. M. [Russian Academy of Sciences, Space Research Institute (Russian Federation)

2012-04-15T23:59:59.000Z

418

National High Magnetic Field Laboratory Audio Dictionary: Resistive...  

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

and Flash to stream the Magnet Minute Mark Bird Associated Links Making Magnets (audio slideshow) Making Resistive Magnets (article) Meet the Magnets Magnet Science &...

419

Magnetic Field Created by Tile Permanent R. Ravaud, G. Lemarquand, V. Lemarquand  

E-Print Network [OSTI]

1 Magnetic Field Created by Tile Permanent Magnets R. Ravaud, G. Lemarquand, V. Lemarquand Abstract1 This paper presents the analytical calculation of the three components of the magnetic field created by2 tile permanent magnets whose magnetization is either radial or axial. The calculations

Boyer, Edmond

420

Crystal-Field Splitting and Giant Negative Magnetization in  

SciTech Connect (OSTI)

Bimetallic oxalates are a class of layered organic magnets with transi- tion metals M(II) and M'(III) coupled by oxalate molecules in an open honeycomb structure. Of particular interest are the Fe(II)Fe(III) bimetal- lic compounds, which are ferrimagnetically ordered below a transition temperature that ranges from 30 to 48 K, depending on the cation that separates the layers. In small magnetic fields, several of these compounds exhibit giant negative magnetization below a compensation temperature of roughly 2/3 Tc. By studying the behavior of the Kramer's doublet ground state produced by the crystal-field splitting and constructing a reduced Hamiltonian that includes both exchange and spin-orbit and in- teractions, we can explain all of the important behavior of this class of materials: the stability of magnetic order in two dimensions and the existence of magnetic compensation in samples with high transition tem- peratures. We also provide several new predictions for the spin-wave gap and the optical flipping of the magnetic moment.

Fishman, Randy Scott [ORNL; Reboredo, Fernando A [ORNL

2007-01-01T23:59:59.000Z

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421

MISALIGNMENT OF MAGNETIC FIELDS AND OUTFLOWS IN PROTOSTELLAR CORES  

SciTech Connect (OSTI)

We present results of {lambda}1.3 mm dust-polarization observations toward 16 nearby, low-mass protostars, mapped with {approx}2.''5 resolution at CARMA. The results show that magnetic fields in protostellar cores on scales of {approx}1000 AU are not tightly aligned with outflows from the protostars. Rather, the data are consistent with scenarios where outflows and magnetic fields are preferentially misaligned (perpendicular), or where they are randomly aligned. If one assumes that outflows emerge along the rotation axes of circumstellar disks, and that the outflows have not disrupted the fields in the surrounding material, then our results imply that the disks are not aligned with the fields in the cores from which they formed.

Hull, Charles L. H.; Plambeck, Richard L.; Bower, Geoffrey C.; Heiles, Carl; Meredith Hughes, A. [Astronomy Department and Radio Astronomy Laboratory, University of California, Berkeley, CA 94720-3411 (United States); Bolatto, Alberto D.; Jameson, Katherine; Mundy, Lee; Pound, Marc W. [Astronomy Department and Laboratory for Millimeter-wave Astronomy, University of Maryland, College Park, MD 20742 (United States); Carpenter, John M.; Lamb, James W.; Pillai, Thushara [Department of Astronomy, California Institute of Technology, 1200 E. California Blvd., MC 249-17, Pasadena, CA 91125 (United States); Crutcher, Richard M.; Hakobian, Nicholas S.; Kwon, Woojin; Looney, Leslie W. [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W Green Street, Urbana, IL 61801 (United States); Fiege, Jason D.; Franzmann, Erica [Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB R3T 2N2 (Canada); Houde, Martin [Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada); Matthews, Brenda C., E-mail: chat@astro.berkeley.edu [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Rd., Victoria, BC V8P 5C2 (Canada); and others

2013-05-10T23:59:59.000Z

422

Electronic structure of diluted magnetic semiconductor superlattices: In-plane magnetic field effect  

Science Journals Connector (OSTI)

The electronic structure of diluted magnetic semiconductor (DMS) superlattices under an in-plane magnetic field is studied within the framework of the effective-mass theory; the strain effect is also included in the calculation. The numerical results show that an increase of the in-plane magnetic field renders the DMS superlattice from the direct band-gap system to the indirect band-gap system, and spatially separates the electron and the hole by changing the type-I band alignment to a type-II band alignment. The optical transition probability changes from type I to type II and back to type I like at large magnetic field. This phenomenon arises from the interplay among the superlattice potential profile, the external magnetic field, and the sp-d exchange interaction between the carriers and the magnetic ions. The shear strain induces a strong coupling of the light- and heavy-hole states and a transition of the hole ground states from “light”-hole to “heavy”-hole-like states.

Hai-Bin Wu, Kai Chang, and Jian-Bai Xia

2002-04-22T23:59:59.000Z

423

Analytical description for field-line wandering in strong magnetic turbulence  

Science Journals Connector (OSTI)

We investigate analytically the random walk of magnetic field lines. In previous analytical treatments of field line wandering or random walk, it was assumed that the turbulent magnetic field is much weaker than the mean field. In the present paper, we develop an improved analytical method to describe the stochastic properties of turbulent magnetic fields. This approach is an extension of the standard theory of field line wandering and can be applied to weak as well as to strong magnetic turbulence.

A. Shalchi; J. A. le Roux; G. M. Webb; G. P. Zank

2009-12-31T23:59:59.000Z

424

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

SciTech Connect (OSTI)

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

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

2013-12-28T23:59:59.000Z

425

Ferrofluid aggregates phase transitions in the planar magnetic field  

E-Print Network [OSTI]

The influence of the cyclic heating and cooling on properties of the aggregates (aka "ferrofluid clusters") in a ferrofluid, which made on the basis of magnetite nanoparticles, are investigated. The heating of the ferrofluid layer with such aggregates leads to equalization of the concentration between high- and low-concentrated phases. The temperature of the equalization of the phase concentrations was determined at different values of an external constant magnetic field, which was applied parallel to the layer of the ferrofluid. The temperature of the destruction of a periodic structure of the magnetic aggregates, which were formed during cooling of a homogeneous phase of the ferrofluid, was obtained at the different values of the applied external magnetic field.

V. F. Kovalenko; M. V. Petrychuk; B. M. Tanygin; S. I. Shulyma

2014-04-21T23:59:59.000Z

426

Dynamical constraints from field line topology in magnetic flux tubes  

E-Print Network [OSTI]

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

A. R. Yeates; G. Hornig

2011-03-11T23:59:59.000Z

427

MAGNETIC FIELDS AND THE OUTER ROTATION CURVE OF M31  

SciTech Connect (OSTI)

Recent observations of the rotation curve of M31 show a rise of the outer part that cannot be understood in terms of standard dark matter models or perturbations of the galactic disk by M31's satellites. Here, we propose an explanation of this dynamical feature based on the influence of the magnetic field within the thin disk. We have considered standard mass models for the luminous mass distribution, a Navarro-Frenk-White model to describe the dark halo, and we have added up the contribution to the rotation curve of a magnetic field in the disk, which is described by an axisymmetric pattern. Our conclusion is that a significant improvement of the fit in the outer part is obtained when magnetic effects are considered. The best-fit solution requires an amplitude of {approx}4 {mu}G with a weak radial dependence between 10 and 38 kpc.

Ruiz-Granados, B.; Rubino-Martin, J. A. [Instituto de Astrofisica de Canarias (IAC), E-38200, La Laguna, Tenerife (Spain); Florido, E.; Battaner, E. [Departamento Fisica Teorica y del Cosmos, Universidad de Granada, Granada (Spain)

2010-11-01T23:59:59.000Z

428

Mean-field analysis of ground state and low-lying electric dipole strength in $^{22}$C  

E-Print Network [OSTI]

Properties of neutron-rich $^{22}$C are studied using the mean-field approach with Skyrme energy density functionals. Its weak binding and large total reaction cross section, which are suggested by recent experiments, are simulated by modifying the central part of Skyrme potential. Calculating $E1$ strength distribution by using the random-phase approximation, we investigate developments of low-lying electric dipole ($E1$) strength and a contribution of core excitations of $^{20}$C. As the neutron Fermi level approaches the zero energy threshold ($\\varepsilon_F >\\sim -1$ MeV), we find that the low-lying $E1$ strength exceeds the energy-weighted cluster sum rule, which indicates an importance of the core excitations with the $1d_{5/2}$ orbit.

Tsunenori Inakura; W. Horiuchi; Y. Suzuki; T. Nakatsukasa

2014-05-30T23:59:59.000Z

429

What is a flux tube? On the magnetic field topology of buoyant flux structures  

E-Print Network [OSTI]

study the topology of field lines threading buoyant magnetic flux struc- tures. The magnetic structures on the parameters, the system exhibits varying degrees of symmetry. By integrating along magnetic field lines of the evolution, and therefore the degree of symmetry, the resulting magnetic structures can have field lines

430

LOW ENERGY ELECTRON TRANSPORT BY RECONNECTED MAGNETIC FIELDS AROUND MARS  

E-Print Network [OSTI]

presents a significant ionospheric obstacle to the solar wind. Moreover, the presence of strong crustalLOW ENERGY ELECTRON TRANSPORT BY RECONNECTED MAGNETIC FIELDS AROUND MARS A DISSERTATION SUBMITTED;Abstract The solar wind interaction with Mars has been studied extensively through satellite observations

431

Observation of conical electron distributions over Martian crustal magnetic fields  

E-Print Network [OSTI]

]. Although the main obstacle to the solar wind is the Martian ionosphere, the strong crustal magnetic fields. The energy spectra of the conics exhibit substantial decreases in all energy levels in relation (draped IMF direction, solar wind pressure, and EUV flux) do not affect the observation of the events

California at Berkeley, University of

432

Visualizing Planetary Magnetic Fields (and Why You Should Care)  

E-Print Network [OSTI]

, Berkeley; 2University of Colorado at Boulder; 3Center of Science Education, Space Sciences Laboratory (CSE@SSL), University of California, Berkeley esea c , Out eac Activities, and Their Impacts II Posters esea c , Out eac Activities, and Their Impacts II Posters Introduction · The magnetic fields of the large terrestrial planets

Fillingim, Matthew

433

Bifurcation of the fmode in presence of nonuniform magnetic field  

E-Print Network [OSTI]

of the bifurcation and plausibly a continuous spectrum of the f � mode in standard k# diagram in our sim� ulations & Heyvaerts (1987) on MHD modes in a periodic magnetic field, but not the f�mode. E#ect of surface ten� sion

Brandenburg, Axel

434

On magnetic fields in broad-line blazars  

E-Print Network [OSTI]

High energy spectra of broad-line blazars can be reproduced by both synchrotron-self-Compton (SSC) models and external-Compton (EC) models. However, as is known from numerical modeling, SSC scenarios require much weaker magnetic field than EC ones. In this paper we quantify these results analytically.

R. Moderski; M. Sikora

2006-12-13T23:59:59.000Z

435

Stiff magnetic field lines. I. A geometrical foundation  

Science Journals Connector (OSTI)

It is shown that the foliation of a space-time manifold of codimension 2 provides a basis for the study of the deformation of magnetic field lines. It is found that the fluid flow ... the curvature vector of a no...

G. Prasad

1981-03-01T23:59:59.000Z

436

Novel Lifshitz point for chiral transition in the magnetic field  

E-Print Network [OSTI]

Based on the generalized Ginzburg-Landau theory, chiral phase transition is discussed in the presence of magnetic field. Considering the chiral density wave we show chiral anomaly gives rise to an inhomogeneous chiral phase for nonzero quark-number chemical potential. Novel Lifshitz point appears on the vanishing chemical potential line, which may be directly explored by the lattice QCD simulation.

T. Tatsumi; K. Nishiyama; S. Karasawa

2014-05-09T23:59:59.000Z

437

On the Magnetic Field of a Rotating Molecule  

Science Journals Connector (OSTI)

The space distribution and magnitude of electronic currents in a rotating molecule with a ?1 ground state are re-examined. An evaluation of the magnetic field set up by the rotation is attempted, and the results are used to interpret the width of radiofrequency resonance lines of some alkali halides.

G. C. Wick

1948-01-01T23:59:59.000Z

438

New approaches to thermoelectric cooling effects in magnetic fields  

SciTech Connect (OSTI)

The authors review thermoelectric effects in a magnetic field at a phenomenological level. Discussions of the limiting performance and problems with its computation for both Peltier and Ettingshausen coolers are presented. New principles are discussed to guide the materials scientist in the search for better Ettingshausen materials, and a brief review of the subtle measurement problems is presented.

Migliori, A.; Darling, T.W.; Freibert, F.; Trugman, S.A.; Moshopoulou, E. [Los Alamos National Lab., NM (United States); Sarrao, J.L. [Florida State Univ., Tallahassee, FL (United States)

1997-08-01T23:59:59.000Z

439

Electron Cyclotron Heating in a Non-Uniform Magnetic Field  

E-Print Network [OSTI]

Electron Cyclotron Heating in a Non-Uniform Magnetic Field by J.e. Sprott December 1968 Presented pulse. IN1RODUCTION Most previous theories of electron cyclotron resonance heating have dealt primarily will outline a simple theoretical model which can be used to estimate the electron cyclotron heating rate

Sprott, Julien Clinton

440

Far-Infrared Studies of Spin-Peierls Materials in a Magnetic Field  

Science Journals Connector (OSTI)

Both a 20 T superconducting magnet and a 33 T resistive magnet were employed for the magnetic field work. ... Bottom panel:? dashed line, absolute transmission spectra of MEM(TCNQ)2 at 300 K and zero field; solid lines, 5 K transmission ratios of MEM(TCNQ)2 taken as a function of applied magnetic field. ... (47)?Ng, H. K.; Wang, Y. J. Proceedings of the Physical Phenomena at High Magnetic Fields II Conference, Tallahassee, FL, Fisk, Z., Ed.; 1995. ...

G. Li; J. S. Lee; V. C. Long; J. L. Musfeldt; Y. J. Wang; M. Almeida; A. Revcolevschi; G. Dhalenne

1998-03-04T23:59:59.000Z

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


441

MAGNETIC FIELD CONFINEMENT IN THE SOLAR CORONA. II. FIELD-PLASMA INTERACTION B. Fornberg,2  

E-Print Network [OSTI]

MAGNETIC FIELD CONFINEMENT IN THE SOLAR CORONA. II. FIELD-PLASMA INTERACTION N. Flyer,1 B. Fornberg numerically to generate a continuum of solutions with two parameters to control the total azimuthal flux from the study to the solar corona and the energetics of coronal mass ejections and flares. Subject

Fornberg, Bengt

442

Influence of the pulsating electric field on the ECR heating in a nonuniform magnetic field  

SciTech Connect (OSTI)

According to a computer simulation, the randomized pulsating electric field can strongly influence the ECR plasma heating in a nonuniform magnetic field. It has been found out that the electron energy spectrum is shifted to the high energy region. The obtained effect is intended to be used in the ECR sources for effective X-ray generation.

Balmashnov, A. A., E-mail: abalmashnov@sci.pfu.edu.ru; Umnov, A. M. [People's Friendship University of Russia (Russian Federation)

2011-12-15T23:59:59.000Z

443

Development of high temperature superconductors for magnetic field applications  

SciTech Connect (OSTI)

The key requirement for magnetic field applications of high temperature superconductor (HTS) materials is to have conductors with high transport critical current density available for magnet builders. After 3 or 4 years of being without any such object, conductor makers have had recent success in producing simple conductor prototypes. These have permitted the construction of simple HTS magnets having self fields exceeding 1 tesla at 4K. Thus the scientific feasibility of making powerful HTS magnets has been demonstrated. Attention to the technological aspects of making HTS conductors for magnets with strong flux pinning and reduced superconducting granularity is now sensible and attractive. However, extrinsic defects such as filament sausaging, cracking, misaligned grains and other perturbation to long range current flow must be controlled at a low level if the benefit of intrinsic improvements to the critical current density is to be maintained in the conductor form. Due to the great complexity of the HTS materials, there is sometimes confusion as to whether a given sample has an intrinsically or extrinsically limited critical current density. Systematic microstructure variation experiments and resistive transition analysis are shown to be particularly helpful in this phase of conductor development.

Larbalestier, D.C.

1991-01-01T23:59:59.000Z

444

Development of high temperature superconductors for magnetic field applications  

SciTech Connect (OSTI)

The key requirement for magnetic field applications of high temperature superconductor (HTS) materials is to have conductors with high transport critical current density available for magnet builders. After 3 or 4 years of being without any such object, conductor makers have had recent success in producing simple conductor prototypes. These have permitted the construction of simple HTS magnets having self fields exceeding 1 tesla at 4K. Thus the scientific feasibility of making powerful HTS magnets has been demonstrated. Attention to the technological aspects of making HTS conductors for magnets with strong flux pinning and reduced superconducting granularity is now sensible and attractive. However, extrinsic defects such as filament sausaging, cracking, misaligned grains and other perturbation to long range current flow must be controlled at a low level if the benefit of intrinsic improvements to the critical current density is to be maintained in the conductor form. Due to the great complexity of the HTS materials, there is sometimes confusion as to whether a given sample has an intrinsically or extrinsically limited critical current density. Systematic microstructure variation experiments and resistive transition analysis are shown to be particularly helpful in this phase of conductor development.

Larbalestier, D.C.

1991-12-31T23:59:59.000Z

445

Magnetic field calculations for iron oxide nanoparticles for MRI  

Science Journals Connector (OSTI)

The susceptibility effects of superparamagnetic iron oxide nanoparticles (SPIONs) functionalized with triethylenglycol (TREG) and Polyethylen Glycol (PEG) has been studied those nanoparticles have the necessary properties to be used in the clinic as contrast media in imaging by MRI[1–3]. We are considering the behavior of the magnetic field as plane wave to explain the electrical and magnetic field produced by SPIONs. Images were acquired on a 1.5T imager Philips using mFFE Sequence. Three glass capillary tubes with a) TREG (10nm) concentration of 300 ?g/ml and PEGCOOH 6000(10nm) with 300 ?g/ml and 2% agarosa. Magnetic field simulations were calculated in Matlab. The plane wave that comes in contact with a sphere of radius a an propagation constant k1 and it is in an homogeneous space k2. We consider that the electric field is linearly polarized on x-direction with a propagation on z-positive-axis. The secondary induced field can be explained from the interior of the sphere and valid exterior points. The referred waves are transmitted and reflected this is valid only when the wavelength is smaller than the radius of the sphere. The obtained vibrational mode is an answer of the electrical oscillation and this is projection of the disturbed magnetic field. TREG-SPIONs produce more serious susceptibility artefacts compared to PEG-SPIONs. This study is promissory due to the concordance of the results of the simulations and the inhomogeneities showed in the MR images.

2014-01-01T23:59:59.000Z

446

THE MAGNETIC CONFINEMENT OF ELECTRON AND PHOTON DOSE PROFILES AND THE POSSIBLE EFFECT OF THE MAGNETIC FIELD ON  

E-Print Network [OSTI]

THE MAGNETIC CONFINEMENT OF ELECTRON AND PHOTON DOSE PROFILES AND THE POSSIBLE EFFECT OF THE MAGNETIC FIELD ON RELATIVE BIOLOGICAL EFFECTIVENESS by Yu Chen A dissertation submitted in partial magnetic field can significantly improve electron beam dose profiles. This could permit improved targeting

Becchetti, Fred

447

Noninvasive valve monitor using constant magnetic and/or DC electromagnetic field  

DOE Patents [OSTI]

One or more sources of steady magnetic field are carefully located on the outside of a valve body. The constant magnetic field is transmitted into the valve body and valve internals. A magnetic field detector carefully located on the outside of the valve body detects the intensity of the magnetic field at its location. As the position of a valve internal part is changed, there is an alteration in the magnetic field in the valve, and a consequent change in the detected magnetic field. Changes in the detected signal provide an indication of the position and motion of the valve internals.

Casada, D.A.; Haynes, H.D.

1993-08-17T23:59:59.000Z

448

Resistive stability of magnetic dipole and other axisymmetric closed field line configurations  

E-Print Network [OSTI]

Resistive stability of magnetic dipole and other axisymmetric closed field line configurations by axisymmetric closed line poloidal magnetic fields are common both in nature (examples are stellar and planetary stability is provided by favorable average magnetic field line curvature, many of the closed field line

449

EHLJPSJY---30/Aug/92 ASYMPTOTICS OF HEAVY ATOMS IN HIGH MAGNETIC FIELDS  

E-Print Network [OSTI]

stronger [1]. This field results, presumably, from the trapping of magnetic field lines duringEHLJPSJY---30/Aug/92 ASYMPTOTICS OF HEAVY ATOMS IN HIGH MAGNETIC FIELDS: I. LOWEST LANDAU BAND in a magnetic field B is evaluated exactly to leading order as Z ! 1. In this and a companion work [28] we show

450

Tokamak with mechanical compression of toroidal magnetic field  

DOE Patents [OSTI]

A tokamak apparatus includes a pressure vessel for defining a reservoir and confining liquid therein. A collapsible toroidal liner disposed within the pressure vessel defines a toroidal space within the liner. Liquid metal fills the reservoir outside said liner. A toroidal magnetic field is developed within the toroidal space about the major axis thereof. A toroidal plasma is developed within the toroidal space about the major axis thereof. Pressure is applied to the liquid metal to collapse the liner and reduce the volume of the toroidal space, thereby increasing the toroidal magnetic flux density therein.

Ohkawa, Tihiro (La Jolla, CA)

1981-01-01T23:59:59.000Z

451

National High Magnetic Field Laboratory Audio Dictionary: Hybrid...  

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

Hybrid Magnet? Now Playing: What's a Hybrid Magnet? Enable Javascript and Flash to stream the Magnet Minute Scott Hannahs Associated Links The World's Strongest Magnet (audio...

452

National High Magnetic Field Laboratory Audio Dictionary: Permanent...  

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

Permanent Magnet? Now Playing: What's a Permanent Magnet? Enable Javascript and Flash to stream the Magnet Minute Scott Hannahs Associated Links Magnets from Mini to Mighty Meet...

453

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

SciTech Connect (OSTI)

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

John Rhoads, Eric Edlund and Hantao Ji

2013-04-17T23:59:59.000Z

454

An electromagnetic drift instability in the magnetic reconnection experiment and its importance for magnetic reconnectiona...  

E-Print Network [OSTI]

online 21 July 2005 The role which resistivity plays in breaking magnetic field lines, heating the plasma near the X line. After they reach a region of appreciable magnetic field strength, say after traveling, and plasma-field slippage during magnetic reconnection is discussed. Magnetic fluctuations are observed

Ji, Hantao

455

Voltage spike detection in high field superconducting accelerator magnets  

SciTech Connect (OSTI)

A measurement system for the detection of small magnetic flux changes in superconducting magnets, which are due to either mechanical motion of the conductor or flux jump, has been developed at Fermilab. These flux changes are detected as small amplitude, short duration voltage spikes, which are {approx}15mV in magnitude and lasts for {approx}30 {micro}sec. The detection system combines an analog circuit for the signal conditioning of two coil segments and a fast data acquisition system for digitizing the results, performing threshold detection, and storing the resultant data. The design of the spike detection system along with the modeling results and noise analysis will be presented. Data from tests of high field Nb{sub 3}Sn magnets at currents up to {approx}20KA will also be shown.

Orris, D.F.; Carcagno, R.; Feher, S.; Makulski, A.; Pischalnikov, Y.M.; /Fermilab

2004-12-01T23:59:59.000Z

456

Magnetism  

Science Journals Connector (OSTI)

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

E. W. LEE

1972-03-31T23:59:59.000Z

457

Coriolis emf as the real generator of solar magnetic field and a new model of the reversal of the general solar magnetic field  

Science Journals Connector (OSTI)

Generation of general solar magnetic field as proposed by Cowling (1945, 1953) and Drobyshevski (1977) from the Coriolis emf is reconsidered and a new mechanism of the reversal of teh general solar magnetic fi...

L. Manihar Singh; L. Randhoni Devi

458

Interaction of magnetic field and magnetic history in high-temperature superconductors  

Science Journals Connector (OSTI)

Yttrium barium copper oxide (YBCO) coated conductors are now the most promising high-temperature superconducting tapes in terms of current capacity and price. One form of these conductors utilizes YBCO films on Ni–W metallic tapes and is being considered for a number of power engineering applications. In these applications the conductor will carry an ac current leading to energy losses which are the focus of significant technical and experimental efforts. Our measurements of the ac losses of YBCO/Ni–W conductors carrying ac currents in applied dc magnetic fields have revealed a complex interaction between the magnetic materials present the geometry of the conductor the ac and dc magnetic fields and the electromagnetic “history” of the sample. The investigation of this interaction is the main subject of this paper.

Francesco Grilli; Stephen P. Ashworth; Leonardo Civale

2007-01-01T23:59:59.000Z

459

Millimeter Scale Alignment of Magnetic Nanoparticle Functionalized Microtubules in Magnetic Fields  

E-Print Network [OSTI]

, transporting cargo up to a meter in biological systems.1 Harnessing the unique properties of this motor direction of the cargo-laden motors and potentially enable the assembly of complex nanostruc- tures. To date techniques,4 by viscous forces,5 or by strong magnetic or electric fields applied during tubule

Hancock, William O.

460

Nonlinear electron acoustic waves in presence of shear magnetic field  

SciTech Connect (OSTI)

Nonlinear electron acoustic waves are studied in a quasineutral plasma in the presence of a variable magnetic field. The fluid model is used to describe the dynamics of two temperature electron species in a stationary positively charged ion background. Linear analysis of the governing equations manifests dispersion relation of electron magneto sonic wave. Whereas, nonlinear wave dynamics is being investigated by introducing Lagrangian variable method in long wavelength limit. It is shown from finite amplitude analysis that the nonlinear wave characteristics are well depicted by KdV equation. The wave dispersion arising in quasineutral plasma is induced by transverse magnetic field component. The results are discussed in the context of plasma of Earth's magnetosphere.

Dutta, Manjistha; Khan, Manoranjan [Department of Instrumentation Science, Jadavpur University, Kolkata 700 032 (India)] [Department of Instrumentation Science, Jadavpur University, Kolkata 700 032 (India); Ghosh, Samiran [Department of Applied Mathematics, University of Calcutta 92, Acharya Prafulla Chandra Road, Kolkata 700 009 (India)] [Department of Applied Mathematics, University of Calcutta 92, Acharya Prafulla Chandra Road, Kolkata 700 009 (India); Chakrabarti, Nikhil [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India)] [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India)

2013-12-15T23:59:59.000Z

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


461

Charge-Transfer Induced Magnetic Field Effects of Nano-Carbon Heterojunctions  

E-Print Network [OSTI]

Room temperature magnetic field effects have not been definitively observed in either single-walled carbon nanotubes (SWCNTs) or C60 under a small magnetic field due to their weak hyperfine interaction and slight difference of g-factor between...

Qin, Wei; Gong, Maogang; Shastry, Tejas; Hersam, Mark C.; Ren, Sheqiang

2014-08-22T23:59:59.000Z

462

Hamilton flow generated by field lines near a toroidal magnetic surface  

Science Journals Connector (OSTI)

A method is described for obtaining the Hamiltonian of a vacuum magnetic field in a given 3D toroidal magnetic surface (superconducting shell). This method is ... of the expansion of a rotational transform of field

A. A. Skovoroda

2013-07-01T23:59:59.000Z

463

The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on RBSP  

Science Journals Connector (OSTI)

The Electric and Magnetic Field Instrument and Integrated Science (EMFISIS) investigation on the NASA Radiation ... mission provides key wave and very low frequency magnetic field measurements to understand radia...

C. A. Kletzing; W. S. Kurth; M. Acuna; R. J. MacDowall…

2014-01-01T23:59:59.000Z

464

The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on RBSP  

Science Journals Connector (OSTI)

The Electric and Magnetic Field Instrument and Integrated Science (EMFISIS) investigation on the NASA Radiation ... mission provides key wave and very low frequency magnetic field measurements to understand radia...

C. A. Kletzing; W. S. Kurth; M. Acuna; R. J. MacDowall…

2013-11-01T23:59:59.000Z

465

MagLab and Japan Join Forces on High-field Magnet Research (August...  

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

and Japan Join Forces on High-field Magnet Research Posted: August 13, 2014 Contact: David Larbalestier TALLAHASSEE, Fla. - The National High Magnetic Field Laboratory (MagLab) has...

466

Conference Summary: The Cosmic Agitator - Magnetic Fields in the Galaxy  

E-Print Network [OSTI]

We present a summary of the conference "The Cosmic Agitator: Magnetic Fields in the Galaxy" held in Lexington KY in 2008 Mar 26-29. The presentation draws primarily from material in the slides prepared for the Conference Summary by one of us (Carl Heiles). Interested readers may navigate to the conference web site given in the paper to view the posted presentations in detail.

T. H. Troland; C. Heiles; A. P. Sarma; G. J. Ferland; R. M. Crutcher; C. L. Brogan

2008-04-21T23:59:59.000Z

467

Hig Resolution Seismometer Insensitive to Extremely Strong Magnetic Fields  

SciTech Connect (OSTI)

A highly sensitive broadband seismic sensor has been developed successfully to be used in beam focusing systems of particale accelerators. The sensor is completely insensitive to extremely strong magnetic fields and to hard radiation conditions that exist at the place of their installation. A unique remote sensor calibration method has been invented and implemented. Several such sensors were sold to LAPP (LAPP-IN2P3/CNRS-Université de Savoie; Laboratoire d'Annecy-le-Vieux de Physique des Particules)

Abramovich, Igor A

2009-07-14T23:59:59.000Z

468

Magnetic Field-Line Reconnection in a Toroidal Plasma  

Science Journals Connector (OSTI)

The magnetic field-line reconnection is investigated in detail by rapidly reversing the toroidal current in a torus plasma. The reconnection brings about an explosive increase in the plasma pressure in a quite narrow region where a shocklike structure is observed. A strong plasma acceleration and an anomalous resistivity due to the reconnection are estimated by the magnetohydrodynamics equations with the variables obtained from the experiment.

S. Iizuka; Y. Minamitani; H. Tanaca; Y. Kiwamoto

1984-08-27T23:59:59.000Z

469

Magnetic field sensors using 13-spin cat states  

E-Print Network [OSTI]

Measurement devices could benefit from entangled correlations to yield a measurement sensitivity approaching the physical Heisenberg limit. Building upon previous magnetometric work using pseudo-entangled spin states in solution-state NMR, we present two conceptual advancements to better prepare and interpret the pseudo-entanglement resource as well as the use of a 13-spin cat state to measure the local magnetic field with a sensitivity beyond the standard quantum limit.

Stephanie Simmons; Jonathan A. Jones; Steven D. Karlen; Arzhang Ardavan; John J. L. Morton

2010-11-24T23:59:59.000Z

470

STABILITY OF THE TOROIDAL MAGNETIC FIELD IN STELLAR RADIATION ZONES  

SciTech Connect (OSTI)

The stability of the magnetic field in radiation zones is of crucial importance for mixing, angular momentum transport, etc. We consider the stability properties of a star containing a predominant toroidal field in spherical geometry by means of a linear stability in the Boussinesq approximation taking into account the effect of thermal conductivity. We calculate the growth rate of instability and analyze in detail the effects of stable stratification and heat transport. We argue that the stabilizing influence of gravity can never entirely suppress the instability caused by electric currents in radiation zones. However, the stable stratification can essentially decrease the growth rate of instability.

Bonanno, Alfio [INAF, Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania (Italy); Urpin, Vadim, E-mail: alfio.bonanno@inaf.it, E-mail: vadim.urpin@uv.es [INFN, Sezione di Catania, Via S. Sofia 72, 95123 Catania (Italy)

2012-03-10T23:59:59.000Z

471

Progress In Electromagnetics Research B, Vol. 13, 120, 2009 MAGNETIC FIELD PRODUCED BY A TILE  

E-Print Network [OSTI]

by permanent magnets is very useful for optimizing alternate magnet structures or magnetic couplings PERMANENT MAGNET WHOSE POLARIZATION IS BOTH UNIFORM AND TANGENTIAL R. Ravaud, G. Lemarquand, V. Lemarquand field produced by a tile permanent magnet whose polarization is both tangential and uniform

Paris-Sud XI, Université de

472

Interior Permanent Magnet Reluctance Machine with Brushless Field Excitation  

SciTech Connect (OSTI)

In a conventional permanent magnet (PM) machine, the air-gap flux produced by the PM is fixed. It is difficult to enhance the air-gap flux density due to limitations of the PM in a series-magnetic circuit. However, the air-gap flux density can be weakened by using power electronic field weakening to the limit of demagnetization of the PMs. This paper presents the test results of controlling the PM air-gap flux density through the use of a stationary brushless excitation coil in a reluctance interior permanent magnet with brushless field excitation (RIPM-BFE) motor. Through the use of this technology the air-gap flux density can be either enhanced or weakened. There is no concern with demagnetizing the PMs during field weakening. The leakage flux of the excitation coil through the PMs is blocked. The prototype motor built on this principle confirms the concept of flux enhancement and weakening through the use of excitation coils.

Wiles, R.H.

2005-10-07T23:59:59.000Z

473

Ising spin glass in a transverse magnetic field  

Science Journals Connector (OSTI)

We study the three-dimensional quantum Ising spin glass in a transverse magnetic field following the evolution of the bond probability distribution under renormalization-group transformations. The phase diagram (critical temperature Tc vs transverse field ?) we obtain shows a finite slope near T=0, in contrast with the infinite slope for the pure case. Our results compare very well with the experimental data recently obtained for the dipolar Ising spin glass LiHo0.167Y0.833F4, in a transverse field. This indicates that this system is more appropriately described by a model with short-range interactions than by an equivalent Sherrington-Kirkpatrick model in a transverse field.

Beatriz Boechat, Raimundo R. dos Santos, and M. A. Continentino

1994-03-01T23:59:59.000Z

474

Theory of Bosons in two-leg ladders with large magnetic fields  

E-Print Network [OSTI]

We calculate the ground state of a Bose gas trapped on a two-leg ladder where Raman-induced hopping mimics the effect of a large magnetic field. In the mean-field limit, where there are large numbers of particles per site, this maps onto a uniformly frustrated two-leg ladder classical spin model. The net particle current always vanishes in the ground state, but generically there is a finite "chiral current", corresponding to equal and opposite flow on the two legs. We vary the strength of the hopping across the rungs of the ladder and the interaction between the bosons. We find three phases: (1) A "saturated chiral current phase" (SCCP), where the density is uniform and the chiral current is simply related to the strength of the magnetic field. In this state the only broken symmetry is the $U(1)$ condensate phase. (2) A "biased ladder phase" (BLP), where the density is higher on one leg than the other. The fluid velocity is higher on the lower density leg, so the net current is zero. In addition to the $U(1)$ condensate phase, this has a broken $Z_2$ reflection symmetry. (3) A "modulated density phase" (MDP), where the atomic density is modulated along the ladder. In addition to the $U(1)$ condensate phase, this has a second broken $U(1)$ symmetry corresponding to translations of the density wave. We further study the fluctuations of the condensate in the BLP, finding a roton-maxon like excitation spectrum. Decreasing the hopping along the rungs softens the spectrum. As the energy of the "roton" reaches to zero, the BLP becomes unstable. We describe the experimental signatures of these phases, including the response to changing the frequency of the Raman transition.

Ran Wei; Erich J. Mueller

2014-05-01T23:59:59.000Z

475

The Physical Origin of the Scattering Polarization of the Na I D-Lines in the Presence of Weak Magnetic Fields  

E-Print Network [OSTI]

We demonstrate that the atomic alignment of the hyperfine-structure components of the ground level S$_{1/2}$ of Na {\\sc i} and of the upper level P$_{1/2}$ of the D$_1$ line are practically negligible for magnetic strengths $B>10 \\rm G$, and virtually zero for $B\\ga 100 \\rm G$. This occurs independently of the magnetic-field inclination on the stellar surface (also, in particular, for vertical fields). Consequently, the characteristic antisymmetric linear-polarization signature of the scattered light in the D$_1$ line is practically suppressed in the presence of magnetic fields larger than 10 G, regardless of their inclination. Remarkably, we find that the scattering polarization amplitude of the D$_2$ line increases steadily with the magnetic strength, for vertical fields above 10 G, while the contribution of alignment to the polarization of the D$_1$ line rapidly decreases. Therefore, we suggest that spectropolarimetric observations of the ``quiet'' solar chromosphere showing significant linear polarization peaks in both D$_1$ and D$_2$ cannot be interpreted in terms of one-component magnetic field models, implying that the magnetic structuring of the solar chromosphere could be substantially more complex than previously thought.

Javier Trujillo-Bueno; Roberto Casini; Marco Landolfi; Egidio Landi Degl'Innocenti

2002-01-23T23:59:59.000Z

476

High Magnetic Field Processing - A Heat-Free Heat Treating Method  

SciTech Connect (OSTI)

The High and Thermal Magnetic Processing/Electro-magnetic Acoustic Transducer (HTMP/EMAT) technology has been shown to be an enabling disruptive materials processing technology, that can achieve significant improvements in microstructure and consequently material performance beyond that achievable through conventional processing, and will lead to the next generation of advanced performance structural and functional materials. HTMP exposure increased the reaction kinetics enabling refinement of microstructural features such as finer martensite lath size, and finer, more copious, homogeneous dispersions of strengthening carbides leading to combined strength and toughness improvements in bainitic steels. When induction heating is applied in a high magnetic field environment, the induction heating coil is configured so that high intensity acoustic/ultrasonic treatment occurs naturally. The configuration results in a highly effective electromagnetic acoustical transducer (EMAT). HTMP combined with applying high-field EMAT, produce a non-contact ultrasonic treatment that can be used to process metal alloys in either the liquid state resulting in significant microstructural changes over conventional processing. Proof-of-principle experiments on cast irons resulted in homogeneous microstructures in small castings along with improved casting surface appearance. The experiment showed that by exposing liquid metal to the non-contact acoustic/ultrasonic processing technology developed using HMFP/EMAT wrought-like microstructures were developed in cast components. This Energy Intensive Processes (EIP) project sponsored by the DOE EERE Advanced Manufacturing Office (AMO) demonstrated the foll