Powered by Deep Web Technologies
Note: This page contains sample records for the topic "magnetic field lines" 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

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

2

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

3

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...

4

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...

5

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

6

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

7

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

8

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

9

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

10

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

11

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

12

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

13

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

14

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

15

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

16

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

17

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

18

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

19

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

20

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

Note: This page contains sample records for the topic "magnetic field lines" 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

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

22

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

23

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

24

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

25

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

26

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

27

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

28

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

29

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

30

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

31

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

32

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

33

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

34

23Mathematical Model of Magnetic Field Lines -III Mathematically, every point in space near  

E-Print Network [OSTI]

23Mathematical Model of Magnetic Field Lines - III Mathematically, every point in space near shape. The lines that are drawn are called 'magnetic field lines', and if you placed a compass of a magnetic field line. Space Math http://spacemath.gsfc.nasa.gov #12;23Answer Key Problem 1 - cos 2 sin rd M

35

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

36

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

37

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

38

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

39

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

40

Latitude Distribution of Interplanetary Magnetic Field Lines Rooted in Active Regions  

Science Journals Connector (OSTI)

Electrons, accelerated in solar active regions to ? 10 keV, escape along open magnetic field lines and generate plasma radiation (Type III bursts ... Here we describe the latitude distribution of the field lines ...

G. A. Dulk; J. L. Steinberg; S. Hoang…

1986-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic field lines" 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

Spatial Structure and Field-Line Diffusion in Transverse Magnetic Turbulence  

Science Journals Connector (OSTI)

We examine magnetic surfaces and randomization of field lines with fluctuations transverse to a uniform magnetic field. Analogy with passive scalar transport in inviscid 2D flow provides realizations of magnetic surfaces and motivates a nonperturbative statistical approach. The stochastic wandering of magnetic field lines leads to diffusive perpendicular transport. For two-component fluctuations, appropriate for solar wind turbulence, the diffusion coefficient is a nonadditive combination of slab and 2D coefficients, approaching the latter in the small amplitude limit.

W. H. Matthaeus; P. C. Gray; D. H. Pontius; Jr.; J. W. Bieber

1995-09-11T23:59:59.000Z

42

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

43

Calculation methods and detection techniques for electric and magnetic fields from power lines with measurement verification  

E-Print Network [OSTI]

An accurate determination and characterization of electric and magnetic fields produced by power lines is a complex task. Different models must be used for far fields and for near fields. This study is centered on computation and measurement aspects...

Mamishev, Alexander V

2012-06-07T23:59:59.000Z

44

A diagnostic method for probing the possible twist of magnetic field lines in sunspots  

Science Journals Connector (OSTI)

In order to study the three-dimensional structure of sunspot magnetic fields it is necessary to determine whether the field lines are twisted, i.e., if the azimuthal angle of transverse field changes with depth. ...

Shi-Hui Ye; Jie-Hai Jin

1990-10-01T23:59:59.000Z

45

Observation and Interpretation of Magnetic-Field-Line Reconnection and Tearing in a Theta Pinch  

Science Journals Connector (OSTI)

Measurements and calculations are presented of reconnection and tearing of magnetic fields in a theta pinch operated with initial bias and driving fields in opposite directions. Open magnetic field lines reconnect and form magnetic islands on time scales of the order of an Alfvén transit time across the plasma sheath. Implications of these results for plasma confinement are discussed.

J. H. Irby; J. F. Drake; Hans R. Griem

1979-01-22T23:59:59.000Z

46

Zero field line in the magnetic spectra of negatively charged nitrogen-vacancy centers in diamond  

E-Print Network [OSTI]

The dependence of the luminescence of diamonds with negatively charged nitrogen-vacancy centers (NV-) vs. applied magnetic field (magnetic spectrum) was studied. A narrow line in zero magnetic field was discovered. The properties of this line are considerably different from those of other narrow magnetic spectrum lines. Its magnitude is weakly dependent of the orientation of the single-crystal sample to the external magnetic field. This line is also observed in a powdered sample. The shape of the line changes greatly when excitation light polarization is varied. The magnitude of the line has a non-linear relation to excitation light intensity. For low intensities this dependence is close to a square law. To explain the mechanism giving rise to this line in the magnetic spectrum, we suggest a model based on the dipole-dipole interaction between different NV- centers.

S. V. Anishchik; V. G. Vins; A. P. Yelisseyev; N. N. Lukzen; N. L. Lavrik; V. A. Bagryansky

2014-07-02T23:59:59.000Z

47

Stability of localized MHD perturbations in confinement systems with closed magnetic field lines  

Science Journals Connector (OSTI)

Conditions are determined for the stability of a finite-pressure plasma against perturbations localized near a magnetic field line in a magnetic confinement system without average minimum-B. The marginal stabilit...

V. V. Arsenin

2002-09-01T23:59:59.000Z

48

The Interpretation of Magnetograph Results: The Formation of Absorption Lines in a Magnetic Field  

Science Journals Connector (OSTI)

The theory of line formation in a magnetic field is reviewed. It is shown how the ... of the solar atmosphere. The properties of magnetic filaments are reviewed. It is shown how ... interpretation of magnetograph...

J. O. Stenflo

1971-01-01T23:59:59.000Z

49

String behaviour of magnetic field lines and their rotation in neutron star’s interior  

Science Journals Connector (OSTI)

It is found from Maxwell’s equations that the magnetic field lines are good analogues of relativistic strings. The Lorentz force per unit length of magnetic tube is interpretable as Magnus force acting on each in...

R. S. Singh; B. K. Sinha

2005-07-01T23:59:59.000Z

50

"The construction of straight-field-line coordinates adapted to the invariant sets of non-integrable magnetic  

E-Print Network [OSTI]

, and the upward magnetic field-line flux across these surfaces determines how important each surface, we will use the commonly used notation is the toroidal flux, and is called the magnetic field-line;The magnetic field-line action is the line integral of the vector potential piecewise

Hudson, Stuart

51

First-order displacement of a magnetic field line in an Elmo bumpy torus  

Science Journals Connector (OSTI)

A perturbation procedure is employed to derive a formula for the field-line displacement in a magnetic configuration consisting of a dominant (unperturbed) field with closed field lines and a small additional (perturbation) field that causes the perturbed field lines to fail to close on themselves. An expression for the spatial displacement of the perturbed field line per circuit, obtained in a first-order perturbation approximation in the Clebsch representation, is given in terms of an action integral representing a longitudinal adiabatic invariant. Numerical results are also presented to compare the first-order approximation with the exact relation.

D. K. Lee; C. L. Hedrick; J. D. Callen

1986-04-01T23:59:59.000Z

52

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

53

Noncollinear orientation of external magnetic field and flux lines penetrating an isotropic hard superconductor  

Science Journals Connector (OSTI)

Penetration by Abrikosov flux lines of an isotropic hard superconductor in the ... induced by changes in the orientation of external magnetic field has been theoretically investigated. The analysis has ... forces...

S. E. Savel’ev; L. M. Fisher…

1998-11-01T23:59:59.000Z

54

MagLab - Magnetic Field Lines Around a Wire Tutorial (II)  

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

Magnetic Field Lines Around a Wire, II 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...

55

Observations of Unresolved Photospheric Magnetic Fields in Solar Flares Using Fe i and Cr i Lines  

Science Journals Connector (OSTI)

The structure of the photospheric magnetic field during solar flares is examined using echelle spectropolarimetric observations. The study is based on several Fe i and Cr i lines observed at locations correspondi...

M. Gordovskyy; V. G. Lozitsky

2014-10-01T23:59:59.000Z

56

The comparison of the magnetographic magnetic field measured in different spectral lines  

Science Journals Connector (OSTI)

The discrepancies in the values of longitudinal magnetic field obtained from magnetographic records in different spectral lines are considered. On the basis of extensive ... 60 pairs of magnetographic maps for 11...

S. I. Gopasyuk; V. A. Kotov; A. B. Severny; T. T. Tsap

1973-08-01T23:59:59.000Z

57

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

58

Mappings of Magnetic Field Lines in Poloidal Divertor Tokamaks  

Science Journals Connector (OSTI)

Another important concept to control the plasma edge in tokamaks is the socalled poloidal divertor tokamaks (see Wesson (2004)). The magnetic configuration of these tokamaks contains a magnetic surface (a magnetic

Sadrilla S. Abdullaev

2006-01-01T23:59:59.000Z

59

Cross-Field Motion of Plasma Blobs in an Open Magnetic Field Line Configuration  

Science Journals Connector (OSTI)

The radial propagation of blobs generated from plasma instabilities is investigated in an open magnetic field line configuration. Blob cross-field velocities and sizes are obtained from internal probe measurements using pattern recognition. By varying the ion mass, the normalized vertical blob scale a˜ is scanned from a˜1. An analytical expression for the blob velocity including cross-field ion polarization currents, parallel currents to the sheath, and ion-neutral collisions is derived and shows good quantitative agreement with the experimental data. In agreement with previous theoretical studies, this scaling shows that, for a˜field ion polarization currents, while for a˜>1 it is limited by parallel currents to the sheath.

C. Theiler; I. Furno; P. Ricci; A. Fasoli; B. Labit; S. H. Müller; G. Plyushchev

2009-08-03T23:59:59.000Z

60

Nonequilibrium and current sheet formation in line-tied magnetic fields C. S. Ng and A. Bhattacharjee  

E-Print Network [OSTI]

Nonequilibrium and current sheet formation in line-tied magnetic fields C. S. Ng and A the photosphere. The footpoints of the magnetic field in the photosphere are frozen ``line- tied'' . Initially to which field lines are line-tied. If such a smooth equilibrium is deformed continuously by further

Ng, Chung-Sang

Note: This page contains sample records for the topic "magnetic field lines" 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

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

62

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

63

Magnetic-field-line random walk in turbulence: A two-point correlation function description  

Science Journals Connector (OSTI)

The standard theory of field-line random walk is based on the description of turbulence in the wave number space. The latter description takes into account the details of turbulence at small scales. Such details, however, are not important in the theory of random walking magnetic field lines. In the present paper we therefore use simple decorrelation models to estimate the field-line diffusion coefficient. Previous results are recovered as special limits. It is shown that a full analytical description is possible and that the only parameter controlling the field-line diffusion coefficient is the Kubo number.

A. Shalchi; A. Dosch; J. A. le Roux; G. M. Webb; G. P. Zank

2012-02-28T23:59:59.000Z

64

Analytical description of stochastic field-line wandering in magnetic turbulence  

E-Print Network [OSTI]

A non-perturbative nonlinear statistical approach is presented to describe turbulent magnetic systems embedded in a uniform mean magnetic field. A general formula in the form of an ordinary differential equation for magnetic field-line wandering (random walk) is derived. By considering the solution of this equation for different limits several new results are obtained. As an example, it is demonstrated that the stochastic wandering of magnetic field-lines in a two-component turbulence model leads to superdiffusive transport, contrary to an existing diffusive picture. The validity of quasilinear theory for field-line wandering is discussed, with respect to different turbulence geometry models, and previous diffusive results are shown to be deduced in appropriate limits.

A. Shalchi; I. Kourakis

2007-03-14T23:59:59.000Z

65

Magnetic connections of solar formations inside magneto-isolated complexes based on observations of arch structures and calculations of magnetic field lines  

Science Journals Connector (OSTI)

The magnetic connections of solar formations inside magneto-isolated ... corona, as well as from calculations of magnetic field lines. It was found that 65% of the constructed field lines are closed within comple...

V. G. Fainshtein; V. M. Malashchuk…

2013-06-01T23:59:59.000Z

66

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

67

Kubo number and magnetic field line diffusion coefficient for anisotropic magnetic turbulence  

Science Journals Connector (OSTI)

The magnetic field line diffusion coefficients Dx and Dy are obtained by numerical simulations in the case that all the magnetic turbulence correlation lengths lx, ly, and lz are different. We find that the variety of numerical results can be organized in terms of the Kubo number, the definition of which is extended from R=(?B/B0)(l?/l?) to R=(?B/B0)(lz/lx), for lx>~ly. Here, l? (l?) is the correlation length along (perpendicular to) the average field B0=B0e^z. We have anomalous, non-Gaussian transport for R?0.1, in which case the mean square deviation scales nonlinearly with time. For R?1 we have several Gaussian regimes: an almost quasilinear regime for 0.1?R?1, an intermediate, transition regime for 1?R?10, and a percolative regime for R?10. An analytical form of the diffusion coefficient is proposed, Di=D(?Blz/B0lx)?(li/lx)?lx2/lz, which well describes the numerical simulation results in the quasilinear, intermediate, and percolative regimes.

P. Pommois; P. Veltri; G. Zimbardo

2001-05-22T23:59:59.000Z

68

TWIST AND CONNECTIVITY OF MAGNETIC FIELD LINES IN THE SOLAR ACTIVE REGION NOAA 10930  

SciTech Connect (OSTI)

Twist and connectivity of magnetic field lines in the flare-productive active region NOAA 10930 are investigated in terms of the vector magnetograms observed by the Solar Optical Telescope on board the Hinode satellite and the nonlinear force-free field (NLFFF) extrapolation. First, we show that the footpoints of magnetic field lines reconstructed by the NLFFF correspond well to the conjugate pair of highly sheared flare ribbons on the Ca II images, which were observed by Hinode as an X3.4 class flare on 2006 December 13. This demonstrates that the NLFFF extrapolation may be used to analyze the magnetic field connectivity. Second, we find that the twist of magnetic field lines anchored on the flare ribbons increased as the ribbons moved away from the magnetic polarity inversion line in the early phase of the flare. This suggests that magnetic reconnection might commence from a region located below the most strongly twisted field. Third, we reveal that the magnetic flux twisted more than a half turn and gradually increased during the last one day prior to the onset of the flare, and that it quickly decreased for two hours after the flare. This is consistent with the store-and-release scenario of magnetic helicity. However, within this active region, only a small fraction of the flux was twisted by more than one full turn and the field lines that reconnected first were twisted less than one turn. These results imply that the kink mode instability could hardly occur, at least before the onset of flare. Based on our results, we discuss the trigger process of solar flares.

Inoue, S. [National Institute of Information and Communications Technology (NICT), 4-2-1, Nukui-Kitamachi, koganei, Tokyo 184-8795 (Japan); Kusano, K.; Yamamoto, T. T. [Solar-Terrestrial Environment Laboratory, Nagoya University Furo-cho, Chikusa-ku, Nagoya, 464-8601 (Japan); Magara, T. [Department of Astronomy and Space Science, School of Space Research, Kyung Hee University, 1, Seocheon-dong, Giheung-gu, Yongin, Gyeonggi-do, 446-701 (Korea, Republic of); Shiota, D., E-mail: inosato@nict.go.jp [Advanced Science Institute, RIKEN - Institute of Physics and Chemical Research, Wako, Saitama 351-0198 (Japan)

2011-09-10T23:59:59.000Z

69

Observation of magnetic field lines in the vicinity of a superconductor with the naked eye  

E-Print Network [OSTI]

Meissner effect and pinning effect are clearly observed with the naked eye. A GdBaCuO high-temperature superconductor (HTS) disk fabricated by Nippon Steel Corporation, a 100mm cubic NdFeB sintered magnet, and iron wires coated by colored are used. When the HTS is put in the magnetic field of the magnet, it can be observed by the wires that the magnetic field lines are excluded from the superconductor (Meissner effect) as well as are pinned in the superconductor (pinning effect).

Yoshihiko Saito

2008-05-26T23:59:59.000Z

70

Theory of magnetic field line random walk in noisy reduced magnetohydrodynamic turbulence  

SciTech Connect (OSTI)

When a magnetic field consists of a mean part and fluctuations, the stochastic wandering of its field lines is often treated as a diffusive process. Under suitable conditions, a stable value is found for the mean square transverse displacement per unit parallel displacement relative to the mean field. Here, we compute the associated field line diffusion coefficient for a highly anisotropic 'noisy' reduced magnetohydrodynamic model of the magnetic field, which is useful in describing low frequency turbulence in the presence of a strong applied DC mean magnetic field, as may be found, for example, in the solar corona, or in certain laboratory devices. Our approach is nonperturbative, based on Corrsin's independence hypothesis, and makes use of recent advances in understanding factors that control decorrelation over a range of parameters described by the Kubo number. Both Bohm and quasilinear regimes are identified.

Ruffolo, D. [Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400, Thailand and Thailand Center of Excellence in Physics, CHE, Ministry of Education, Bangkok 10400 (Thailand); Matthaeus, W. H. [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States)

2013-01-15T23:59:59.000Z

71

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

Science Journals Connector (OSTI)

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

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

2000-02-01T23:59:59.000Z

72

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

E-Print Network [OSTI]

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

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

1999-07-29T23:59:59.000Z

73

The covariant description of electric and magnetic field lines of null fields: application to Hopf-Ranada solutions  

E-Print Network [OSTI]

The concept of electric and magnetic field lines is intrinsically non-relativistic. Nonetheless, for certain types of fields satisfying certain geometric properties, field lines can be defined covariantly. More precisely, two Lorentz-invariant 2D surfaces in spacetime can be defined such that magnetic and electric field lines are determined, for any observer, by the intersection of those surfaces with spacelike hyperplanes. An instance of this type of field is constituted by the so-called Hopf-Ranada solutions of the source-free Maxwell equations, which have been studied because of their interesting topological properties, namely, linkage of their field lines. In order to describe both geometric and topological properties in a succinct manner, we employ the tools of Geometric Algebra (aka Clifford Algebra) and use the Clebsch representation for the vector potential as well as the Euler representation for both magnetic and electric fields. This description is easily made covariant, thus allowing us to define electric and magnetic field lines covariantly in a compact geometric language. The definitions of field lines can be phrased in terms of 2D surfaces in space. We display those surfaces in different reference frames, showing how those surfaces change under Lorentz transformations while keeping their topological properties. As a byproduct we also obtain relations between optical helicity, optical chirality and generalizations thereof, and their conservation laws.

S. J. van Enk

2013-02-12T23:59:59.000Z

74

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

75

Bounds on the length of magnetic field lines in a two-dimensional plasma  

Science Journals Connector (OSTI)

Magnetic field lines in ideal turbulent plasmas tend to become quite complicated and their length to grow in time. Diffusivity allows for reconnection and possible shortening, but this fact has not so far been rigorously quantified. We show that in a two-dimensional diffusive plasma the mean length of field lines stays bounded for all time. Moreover, these estimates are local, in the sense that the mean values of magnetic field and velocity in the neighborhood of a ball determine bounds for length within the ball, without recourse to external magnitudes.

Manuel Núñez

2001-02-27T23:59:59.000Z

76

Notes on the geometry of magnetic field lines  

Science Journals Connector (OSTI)

By employing a non-holonomic description of the governing equations, the orthogonal flow of steady, rotating, viscous, incompressible, perfectly conducting two-phase fluid flow in the presence of magnetic fiel...

H. K. Pandey; C. Thakur; R. B. Mishra

77

Impact of static magnetic fields on the radial line slot antenna plasma source  

SciTech Connect (OSTI)

The radial line slot antenna plasma source is used in semiconductor device fabrication. As is the case for all plasma sources, ever more strict uniformity control requirements are driven by the precision demands of new device technologies. Large volume diffusion plasmas, of which the radial line slot antenna source is one type, must overcome transport effects or diffusion modes that tend to 'center peak' the plasma density near the wafer being processed. One way to resolve problematic transport effects is the insertion of magnetic fields into the plasma region. In this paper, the impact of the magnetic field on plasma properties is parameterized as a function of slot configuration. The magnetic field orientation and the magnitude of magnetic field are varied in a computational study in which the source is modeled as a two-dimensional axisymmetric quasineutral plasma. This work employs a finite element model simulation. The magnitude of magnetic fields considered is 50 Gauss maximum with a microwave power of 3000 W at a pressure of 20 mTorr. 20 mTorr is chosen as this is a condition where diffusion effects are challenging to counteract. The study showed that there are specific conditions for slot configuration and magnetic field that improve the plasma controllability and some that do not. Plasma property modulation is most effective when the plasma source region is placed at large radius with axial magnetic fields. There are synergistic effects between the slot location and magnetic field that are important and placing large magnetic fields at the chamber edge alone does not result in improved uniformity. Electron cyclotron resonance (ECR) heating and the impact of pulsing the magnetic fields are presented. ECR heating is not important for the conditions relevant to this paper and pulsing is shown to have benefit.

Yoshikawa, Jun; Ventzek, Peter L. G. [Tokyo Electron Ltd. Akasaka Biz Tower, 3-1 Akasaka 5-chome, Minato-ku, Tokyo 107-6325 (Japan)

2013-05-15T23:59:59.000Z

78

Potential Formation in a High-Speed Plasma Flow along Converging Magnetic Field Lines  

Science Journals Connector (OSTI)

The formation of a potential is experimentally investigated in a high-speed collisionless plasma flow injected into a region of converging magnetic field lines. When the plasma passes through this region, a large increase in potential occurs there, resulting in electron acceleration along the magnetic field. A drastic end-plate effect on the generated potential is observed when the plasma comes in contact with the end plate.

N. Sato; Y. Watanabe; R. Hatakeyama; T. Mieno

1988-10-03T23:59:59.000Z

79

Study of the interplay between magnetic shear and resonances using Hamiltonian models for the magnetic field lines  

SciTech Connect (OSTI)

The issue of magnetic confinement in magnetic fusion devices is addressed within a purely magnetic approach. Using some Hamiltonian models for the magnetic field lines, the dual impact of low magnetic shear is shown in a unified way. Away from resonances, it induces a drastic enhancement of magnetic confinement that favors robust internal transport barriers (ITBs) and stochastic transport reduction. When low shear occurs for values of the winding of the magnetic field lines close to low-order rationals, the amplitude thresholds of the resonant modes that break internal transport barriers by allowing a radial stochastic transport of the magnetic field lines may be quite low. The approach can be applied to assess the robustness versus magnetic perturbations of general (almost) integrable magnetic steady states, including nonaxisymmetric ones such as the important single-helicity steady states. This analysis puts a constraint on the tolerable mode amplitudes compatible with ITBs and may be proposed as a possible explanation of diverse experimental and numerical signatures of their collapses.

Firpo, M.-C. [Laboratoire de Physique des Plasmas, CNRS--Ecole Polytechnique, 91128 Palaiseau Cedex (France); Constantinescu, D. [Department of Applied Mathematics, Association Euratom-MECI, University of Craiova, Craiova 200585 (Romania)

2011-03-15T23:59:59.000Z

80

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

Note: This page contains sample records for the topic "magnetic field lines" 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

Nonperturbative broadening of paramagnetic resonance lines by transverse magnetic field gradients  

Science Journals Connector (OSTI)

We experimentally and theoretically study the broadening of paramagnetic resonance lines by transverse magnetic field gradients when a perturbative description is inadequate. The experiments are performed with an evanescent wave magnetometer using an octadecyltrichlorosilane-coated glass cell containing R87b and N2 buffer gas. We find that the transverse broadening of the resonance line is inversely proportional to the square root of the holding field. We also provide a quantitative theoretical explanation of the experimental results.

K. F. Zhao; M. Schaden; Z. Wu

2008-07-30T23:59:59.000Z

82

Random walk of magnetic field lines for different values of the energy-range spectral index  

E-Print Network [OSTI]

An analytical nonlinear description of field-line wandering in partially statistically magnetic systems was proposed recently [A. Shalchi, I. Kourakis, Astronomy and Astrophysics, 470, 405 (2007)]. In this article we investigate the influence of the wave-spectrum in the energy-range onto field line random walk by applying this formulation. It is demonstrated that in all considered cases we clearly obtain a superdiffusive behaviour of the field-lines. If the energy-range spectral index exceeds unity a free-streaming behaviour of the field-lines can be found for all relevant length-scales of turbulence. Since the superdiffusive results obtained for the slab model are exact, it seems that superdiffusion is the normal behavior of field line wandering.

A. Shalchi; I. Kourakis

2007-09-17T23:59:59.000Z

83

Recovery of the global magnetic field configuration of 78 Virginis from Stokes IQUV line profiles  

E-Print Network [OSTI]

The surface magnetic field configuration of the Ap star HD 118022 (78 Vir) has been reconstructed in the framework of the magnetic charge distribution (MCD) method from the analysis of Stokes $IQUV$ spectra obtained using the MuSiCoS spectropolarimeter at Pic du Midi Observatory. Magnetically-sensitive Fe~{\\sc ii} lines were primarily employed in the analysis, supposing that iron is evenly distributed over the stellar surface. We show that the Stokes $IQUV$ profile shapes and variations of 78 Vir can be approximately fit assuming a global magnetic field configuration described by a slightly decentered, inclined magnetic dipole of polar surface intensity approximately 3.3~kG. The derived inclinations of the stellar rotational axis to the line of sight $i=24\\pm 5\\degr$ as well as to the magnetic dipole axis $\\beta=124\\pm5\\degr$ are in good agreement with previous estimations by other authors, whereas the sky-projected position angle\\thanks{$\\Omega$ increases clockwise from the axis to the North Celestial Pole and relates to the azimuth angle $\\Theta$ specified by Landolfi at al.~(\\cite{Landolfi+93}) as $\\Omega=360\\degr-\\Theta$.} of the stellar rotation axis $\\Omega\\sim110\\degr$ is reported here for the first time. In addition, several lines of Cr~{\\sc ii} and Ti~{\\sc ii} were studied, yielding evidence for non-uniform surface distributions of these elements, and magnetic field results similar to those derived from Fe.

V. R. Khalack; G. A. Wade

2006-01-30T23:59:59.000Z

84

Hamilton flow generated by field lines near a toroidal magnetic surface  

SciTech Connect (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 used to derive the expression for the integrable surface Hamiltonian in the form of the expansion of a rotational transform of field lines on embedded near-boundary magnetic surfaces into a Taylor series in the distance from the boundary. This expansion contains the value of the rotational transform and its shear at the boundary surface. It is shown that these quantities are related to the components of the first and second quadratic forms of the boundary surface.

Skovoroda, A. A., E-mail: skovorod@nfi.kiae.ru [National Research Center Kurchatov Institute (Russian Federation)

2013-07-15T23:59:59.000Z

85

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

86

Laser-based diagnostic for tracing magnetic-field lines in spheromaks and other self-organized magnetically confined plasmas  

Science Journals Connector (OSTI)

We are in the process of testing a technique for measuring the magnetic-field line topology in magnetically confined plasmas. The basic idea is to use a high-powerful short-pulse laser to launch a burst of energetic (?100 keV) electrons from a target passing through the plasma of interest; these electrons then generally follow field lines until they strike a solid surface where a burst of x rays is produced and then detected. The field line connection length can be determined from the time delay between the laser pulse and the burst of x rays. The topology of the field lines can be inferred by measuring the connection length as a function of initial target location inside the plasma. Measuring the spatial distribution of the x-ray production will provide further information on the field topology including the effects of magnetic-field fluctuations and stochasticity. The work will eventually include testing the appropriate x-ray detectors measuring the background x-ray emission in a spheromak plasma measuring the energetic electron production by a short-pulse high-power laser and making preliminary measurements of the edge field line topology in the Sustained Spheromak Physics Experiment using a pulsed electron-beam source as a prototype for a laser-based source. This technique may have broad application to a variety of plasma configurations and provide physics data applicable to a wide range of plasma physics problems.

H. S. McLean; D. N. Hill; D. D. Ryutov; H. Chen

2003-01-01T23:59:59.000Z

87

Absorption profiles of alkali-metal D lines in the presence of a static magnetic field  

Science Journals Connector (OSTI)

When atoms are placed in a static magnetic field, they undergo shifts of their energy levels and changes in their transition probabilities. These two effects must be taken into account when considering absorption profiles of alkali-metal D lines, which result from the contribution of many transitions influenced by the laser spectrum and Doppler broadening. The model presented here gives the D-line absorption coefficients of alkali-metal vapors in the presence of an arbitrary static magneitc field. They are evaluated considering various laser polarizations. Experimental measurements of D-line absorption profiles for Rb85, Rb87, and Cs133 isotopes show excellent agreement with theoretical predictions.

P. Tremblay; A. Michaud; M. Levesque; S. Thériault; M. Breton; J. Beaubien; N. Cyr

1990-09-01T23:59:59.000Z

88

Reflectance variation of human blood under a magnetic field at the Ar-ion laser line: feasibility for clinical diagnosis  

Science Journals Connector (OSTI)

Measuring the reflectance variation ?R under dc magnetic field at Ar+ 0.5017-?m laser line for both corpuscle and plasma human blood samples and applying statistical...

Sato, Heihachi; Hayashi, Hidenori; Sugiyama, Mitsugu; Tsuchiya, Shuji

1981-01-01T23:59:59.000Z

89

Axial Distributions of Spectral Line Intensities in the Arc Under the Influence of External Rotating Magnetic Field  

Science Journals Connector (OSTI)

The influence of external rotating magnetic field (RMF) on the electric arc plasma, and therefore the axial distributions of the spectral line intensities and the atomic...

Pavlovic, B V; Mihailidi, T A

1981-01-01T23:59:59.000Z

90

Correlated ESR and NMR line-broadening effect associated with external-magnetic-field inhomogeneities  

Science Journals Connector (OSTI)

The unusual dynamic nuclear polarization (DNP) phenomena at the center of an inhomogeneously broadened ESR line arising from a correlated ESR and NMR line broadening have been investigated for the case of inhomogeneous external magnetic fields. It was found that DNP experimental data obtained for the central Cr3+ ESR and Al27 NMR lines in a single crystal of ruby were consistent with the phenomenological model developed for the correlated ESR and NMR line broadenings arising from the strain and c-axis-variation effects. This result can be taken as a direct verification of the phenomenological model.

Sook Lee and D. C. Power

1980-02-01T23:59:59.000Z

91

Thermonuclear Supernovae: Probing Magnetic Fields by Late-Time IR Line Profiles  

E-Print Network [OSTI]

We study the imprint of magnetic fields B on late-time IR line profiles and light curves of Type Ia Supernovae. As a benchmark, we use the explosion of a Chandrasekhar mass M_{Ch White Dwarf (WD) and, specifically, a delayed detonation model. We assume WDs with initial magnetic surface fields between 1 and 1E9G. We discuss large-scale dipole and small-scale magnetic fields. We find that the [Fe II] line at 1.644 mu can be used to analyze the overall chemical and density structure of the exploding WD up to day 200 without considering B. Subsequently, positron transport and magnetic field effects become important. By day 500, the profile becomes sensitive to the morphology of B and directional dependent for dipole fields. Small or no directional dependence of the spectra is found for small-scale B. After about 200 days, persistent broad-line, flat-topped or stumpy profiles require high density burning which is the signature of a WD close to M_Ch. Narrow peaked profiles are a signature of chemical mixing or sub-...

Penney, R

2014-01-01T23:59:59.000Z

92

Hybrid Simulation of Space Plasmas: Models with Massless Fluid Representation of Electrons. V. Reconnection of Magnetic Field Lines  

Science Journals Connector (OSTI)

This is a survey of literature on hybrid simulation of collisionless reconnection of interplanetary magnetic field lines. The article briefly reviews the simple theoretical models of magnetic reconnection (Petsch...

D. S. Filippychev

2002-07-01T23:59:59.000Z

93

Anomalous diffusion of field lines and charged particles in Arnold-Beltrami-Childress force-free magnetic fields  

SciTech Connect (OSTI)

The cosmic magnetic fields in regions of low plasma pressure and large currents, such as in interstellar space and gaseous nebulae, are force-free in the sense that the Lorentz force vanishes. The three-dimensional Arnold-Beltrami-Childress (ABC) field is an example of a force-free, helical magnetic field. In fluid dynamics, ABC flows are steady state solutions of the Euler equation. The ABC magnetic field lines exhibit a complex and varied structure that is a mix of regular and chaotic trajectories in phase space. The characteristic features of field line trajectories are illustrated through the phase space distribution of finite-distance and asymptotic-distance Lyapunov exponents. In regions of chaotic trajectories, an ensemble-averaged variance of the distance between field lines reveals anomalous diffusion—in fact, superdiffusion—of the field lines. The motion of charged particles in the force-free ABC magnetic fields is different from the flow of passive scalars in ABC flows. The particles do not necessarily follow the field lines and display a variety of dynamical behavior depending on their energy, and their initial pitch-angle. There is an overlap, in space, of the regions in which the field lines and the particle orbits are chaotic. The time evolution of an ensemble of particles, in such regions, can be divided into three categories. For short times, the motion of the particles is essentially ballistic; the ensemble-averaged, mean square displacement is approximately proportional to t{sup 2}, where t is the time of evolution. The intermediate time region is defined by a decay of the velocity autocorrelation function—this being a measure of the time after which the collective dynamics is independent of the initial conditions. For longer times, the particles undergo superdiffusion—the mean square displacement is proportional to t{sup ?}, where ??>?1, and is weakly dependent on the energy of the particles. These super-diffusive characteristics, both of magnetic field lines and of particles moving in these fields, strongly suggest that theories of transport in three-dimensional chaotic magnetic fields need a shift from the usual paradigm of quasilinear diffusion.

Ram, Abhay K. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Dasgupta, Brahmananda [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, Alabama 35805 (United States); Krishnamurthy, V. [Center for Ocean-Land-Atmosphere Studies, George Mason University, Fairfax, Virginia 22030 (United States); Mitra, Dhrubaditya [Nordita, KTH Royal Institute of Technology and Stockholm University, 10691 Stockholm (Sweden)

2014-07-15T23:59:59.000Z

94

Resistivity and Energy Flow in a Plasma Undergoing Magnetic-Field-Line Reconnection  

Science Journals Connector (OSTI)

Detailed time- and space-resolved measurements of the electric fields and currents have been made in a laboratory plasma undergoing magnetic-field-line reconnection. The resistivity normalized to the classical value is found to be spatially inhomogeneous (10

N. Wild; W. Gekelman; R. L. Stenzel

1981-02-02T23:59:59.000Z

95

Automated Technique For Comparison Of Magnetic Field Inversion Lines With Filament Skeletons From The Solar Feature Catalogue  

Science Journals Connector (OSTI)

We present an automated technique for comparison of magnetic field inversion-line maps from SOHO/MDI magnetograms with solar ... component labelling are used to identify nearest inversion lines to filament skelet...

S. S. Ipson; V. V. Zharkova; S. Zharkov; A. K. Benkhalil; J. Aboudarham…

2005-05-01T23:59:59.000Z

96

Hanle effect in the solar Ba II D2 line: a diagnostic tool for chromospheric weak magnetic fields  

E-Print Network [OSTI]

The physics of the solar chromosphere depends in a crucial way on its magnetic structure. However there are presently very few direct magnetic field diagnostics available for this region. Here we investigate the diagnostic potential of the Hanle effect on the Ba II D2 line resonance polarization for the determination of weak chromospheric turbulent magnetic fields......

M. Faurobert; M. Derouich; V. Bommier; J. Arnaud

2008-11-07T23:59:59.000Z

97

Nuclear-Magnetic-Resonance Line Narrowing by a Rotating rf Field  

Science Journals Connector (OSTI)

A nuclear-magnetic-resonance method is explored, which effectively attenuates the dipolar interaction in solids. The experimental technique corresponds to the observation of a free-induction decay in a frame of reference rotating with the frequency of an applied rf field. When the amplitude H1 of this field is much greater than the local field in the solid, and when its frequency is appropriately chosen, the secular part of the dipolar interaction is removed. As a result the rotary saturation line is extremely narrowed. At smaller values of H1, nonsecular terms in the dipolar interaction come into play and contribute to line broadening. These nonsecular effects are investigated both theoretically and experimentally. All the measurements were made in single crystals of calcium fluoride. The calculation of the nonsecular contribution to the line width utilizes the unitary transformation method of Jordhal and Pryce. Theory and experiment are in good agreement.

Moses Lee and Walter I. Goldburg

1965-11-15T23:59:59.000Z

98

ANALYSIS OF it YOHKOH SXT CORONAL LOOPS AND CALCULATED FORCE-FREE MAGNETIC FIELD LINES FROM VECTOR MAGNETOGRAMS  

Science Journals Connector (OSTI)

In this paper some soft X-ray loops observed by Yohkoh/SXT and extrapolated magnetic fields from the vector magnetogram data observed at ... Telescope are compared and analyzed. The computed field lines generally...

Yihua Yan; Takashi Sakurai

1997-08-01T23:59:59.000Z

99

The Effects of Magnetic Fields on Line-Driven Hot-Star Winds  

E-Print Network [OSTI]

This talk summarizes results from recent MHD simulations of the role of a dipole magnetic field in inducing large-scale structure in the line-driven stellar winds of hot, luminous stars. Unlike previous fixed-field analyses, the MHD simulations here take full account of the dynamical competition between the field and the flow. A key result is that the overall degree to which the wind is influenced by the field depends largely on a single, dimensionless `wind magnetic confinement parameter', $\\eta_\\ast (= B_{eq}^2 R_{\\ast}^2/\\dot{M} v_\\infty$), which characterizes the ratio between magnetic field energy density and kinetic energy density of the wind. For weak confinement, $\\eta_\\ast \\le 1$, the field is fully opened by wind outflow, but nonetheless, for confinement as small as $\\eta_\\ast=1/10$ it can have significant back-influence in enhancing the density and reducing the flow speed near the magnetic equator. For stronger confinement, $\\eta_\\ast > 1$, the magnetic field remains closed over limited range of latitude and height above the equatorial surface, but eventually is opened into nearly radial configuration at large radii. Within the closed loops, the flow is channeled toward loop tops into shock collisions that are strong enough to produce hard X-rays. Within the open field region, the equatorial channeling leads to oblique shocks that are again strong enough to produce X-rays and also lead to a thin, dense, slowly outflowing ``disk'' at the magnetic equator.

Asif ud-Doula; Stan Owocki

2003-10-07T23:59:59.000Z

100

PRODUCTION OF LARGE VOLUME CYLINDRICAL RF PLASMA USING CIRCULAR MAGNETIC LINE CUSP FIELD  

Science Journals Connector (OSTI)

A large volume cylindrical rf (radio frequency) plasma source using a circular magnetic line cusp field has been developed for various large scale plasma processings. In this type of plasma source, a capacitively coupled 13.56 \\{MHz\\} rf plasma is produced in a circular magnetic line cusp field. Two versions of the plasma source have been constructed and tasted. The first version has a pair of peripheral rf electrodes placed outside the ionization chamber and is suitable for preparing a large volume uniform plasma. This plasma source can attain uniformity within 107 cm?3 over a 30 cm diameter region. The other which is provided with parallel doughnut plate electrodes forming part of the chamber wall serves as a high current plasma source, where the electron density is proportional to the rf power and equal to 7 × 109 cm?3 for 500 W.

K. YAMAUCHI; M. SHIBAGAKI; A. KONO; K. TAKAHASHI; T. SHEBUYA; E. YABE; K. TAKAYAMA

1993-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic field lines" 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

Topology of magnetic field lines: Chaos and bifurcations emerging from two-action systems  

Science Journals Connector (OSTI)

Nonlinear dynamics of magnetic field lines generated by simple electric current elements are investigated. In general, the magnetic field lines show behavior similar to that of the Hamiltonian systems; in fact, they can be generally transformed into Hamiltonian systems with 1.5 degrees of freedom, obey the Kolmogorov-Arnold-Moser (KAM) theorem, and generate chaotic trajectories. In the case where unperturbed systems are described by two action (slow) and one angle (fast) variables, however, it is found that the periodic orbits of the unperturbed systems vanish for arbitrarily small symmetry-breaking perturbations (a breakdown of the KAM theorem) and drifting or periodic trajectories appear. The mechanism of this phenomenon is investigated analytically by weak nonlinear stability analysis. It is also shown numerically that scattering processes of the perturbed system exhibit typical features of chaotic dynamical systems.

Tomoshige Miyaguchi; Makoto Hosoda; Katsuyuki Imagawa; Katsuhiro Nakamura

2011-01-06T23:59:59.000Z

102

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

103

The conditions for the existence of the electric field opposite to the current along the magnetic field lines in the thin plasma  

Science Journals Connector (OSTI)

The flow of the current along the magnetic field lines in the thin plasma directed opposite to the electric field is considered. The particles moving to the ... current density which are typical for the auroral field

M. V. Samokhin

104

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

105

Study of Rb atomic transitions D1,2 lines in strong magnetic field based on fluorescence spectra of sub -micron thin cell  

E-Print Network [OSTI]

Study of Rb atomic transitions D1,2 lines in strong magnetic field based on fluorescence spectra "forbidden" transitions in magnetic field B are detected and studied. Also, on 87 Rb D1 line, Fg = 1, mF = 0 the levels of the hyperfine structure of the D1,2 lines of 87 Rb atoms in magnetic fields with B varying

Boyer, Edmond

106

The external magnetic field dependence of RF splitting of57Fe hyperfine lines. NMR + Mössbauer double resonance experiment  

Science Journals Connector (OSTI)

We present the results of an experimental investigation of a RF splitting of57Fe hyperfine lines in the regime of NMR and Mössbauer ... have been performed as a function of RF field intensity and static magnetic

F. G. Vagizov

1995-01-01T23:59:59.000Z

107

The Trajectories of Magnetic Field Lines in Tokamaks with Helical Windings  

Science Journals Connector (OSTI)

The distribution of the magnetic lines in a tokamak plasma per — turbed ... is applied to investigate the break-up of magnetic surfaces inside the plasma for large aspect- ... This effect is also investigated int...

I. L. Caldas; M. V. A. P. Heller; S. J. Camargo…

1990-01-01T23:59:59.000Z

108

Magnetic field generation from Alfven waves propagating along helical lines of force  

Science Journals Connector (OSTI)

A static induced magnetization of Alfven waves (IMAW) due to the inverse Faraday effect is defined and studied. The Alfven waves are assumed to propagate along helical lines of force of a force-free ambient magnetic

B. Bera; Chandra Das; B. Chakraborty…

1992-07-01T23:59:59.000Z

109

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

110

HHFW Power Flow Along Magnetic Field Lines In The Scrape-off Layer of NSTX  

SciTech Connect (OSTI)

A significant fraction of high-harmonic fast-wave (HHFW) power applied to NSTX can be lost to the scrape-off layer (SOL) and deposited in bright and hot spirals on the divertor rather than in the core plasma. We show that the HHFW power flows to these spirals along magnetic field lines passing through the SOL in front of the antenna, implying that the HHFW power couples across the entire width of the SOL rather than mostly at the antenna face. This result will help guide future efforts to understand and minimize these edge losses in order to maximize fast wave heating and current drive.

Rory Perkins, et. al.

2012-02-27T23:59:59.000Z

111

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

Science Journals Connector (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...eq..., i.e., the maximum plasma pressure abo...

A. A. Skovoroda

2007-08-01T23:59:59.000Z

112

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

113

Propagation speed of rotation signals for field lines undergoing magnetic reconnection  

SciTech Connect (OSTI)

Reconnection is associated with two bending of the magnetic field lines. Considering the usual plane of a 2D reconnection simulation, the first bending is in-plane and produces the needed topological changes by bringing oppositely directed filed lines in proximity. The second is typical of fast reconnection and is out of plane, leading to the formation of the Hall magnetic field. This second rotation has recently been observed to proceed at superAlfvénic speeds and to carry substantial energy fluxes (Shay et al., Phys. Rev. Lett. 107, 065001 (2011)). We revisit these rotations with a new diagnostics based on dispersing a multitude of virtual probes into a kinetic simulation, akin the approach of multi spacecraft missions. The results of the new diagnostics are compared with the theory of characteristics applied to the two fluid model. The comparison of virtual probes and the method of characteristics confirm the findings relative to the out of plane rotation and uncover the existence of two families of characteristics. Both are observed in the simulation. The early stage of reconnection develops on the slower compressional branch and the later faster phase develops on the faster torsional branch. The superAlfvénic signal is only relevant in the second phase.

Lapenta, Giovanni [Center for mathematical Plasma Astrophysics, Departement Wiskunde, KU Leuven, Universiteit Leuven, Belgium, European Union (Belgium)] [Center for mathematical Plasma Astrophysics, Departement Wiskunde, KU Leuven, Universiteit Leuven, Belgium, European Union (Belgium); Goldman, Martin; Newman, David [Department of Physics, University of Colorado, Boulder, Colorado (United States)] [Department of Physics, University of Colorado, Boulder, Colorado (United States); Markidis, Stefano [KTH Royal Institute of Technology, Stockholm, Sweden, European Union (Sweden)] [KTH Royal Institute of Technology, Stockholm, Sweden, European Union (Sweden)

2013-10-15T23:59:59.000Z

114

Effect of a magnetic field on the excitonic luminescence line shape in a quantum well  

Science Journals Connector (OSTI)

The effect of magnetic field on the excitonic photoluminescence line shape has been studied in a high-quality single GaAs-AlxGa1-xAs quantum well grown by the molecular-beam-epitaxy technique. An increase of magnetic field from 0 to 6 T has been found to result in (1) a decrease in the Lorentzian contribution ?0 to the line shape from ?0(0 T)=0.504±0.01 meV to ?0(6 T)=0.336±0.01 meV due to the formation of a quasi-zero-dimensional density of states. This leads, in turn, to an increase in the exciton dephasing time due to the inhibition of the carrier relaxation, and (2) an increase in the Gaussian contribution from ?(0 T)=0.24 meV to ?(6 T)=0.39 meV, attributed to the shrinking of the exciton wave function in real space; the last effect causing the exciton to become more responsive to the statistical potential fluctuations at the quantum-well interfaces.

I. Aksenov; J. Kusano; Y. Aoyagi; T. Sugano; T. Yasuda; Y. Segawa

1995-02-15T23:59:59.000Z

115

Line narrowing of electromagnetically induced transparency in Rb with a longitudinal magnetic field  

Science Journals Connector (OSTI)

Electromagnetically induced transparency (EIT) experiments in ?-type systems benefit from the use of hot vapor where the thermal averaging results in reducing the width of the EIT resonance well below the natural linewidth. Here, we demonstrate a technique for further reducing the EIT width in room-temperature vapor by the application of a small longitudinal magnetic field. The Zeeman shift of the energy levels results in the formation of several shifted subsystems; the net effect is to create multiple EIT dips each of which is significantly narrower than the original resonance. We observe a reduction by a factor of 3 in the D2 line of Rb87 with a field of 3.2G.

S. M. Iftiquar and Vasant Natarajan

2009-01-12T23:59:59.000Z

116

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,...

117

Observation of higher order NMR larmor lines by SQUID in solids at low magnetic field  

Science Journals Connector (OSTI)

We describe an apparatus allowing the observation of the NMR static longitudinal component of nuclear magnetizationM z by a SQUID at low magnetic fields and atT

M. Kohl; M. Odehnal; V. Pet?í?ek; R. Tichý…

1988-08-01T23:59:59.000Z

118

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

119

Two-dimensional Vlasov solution for a collisionless plasma jet across transverse magnetic field lines with a sheared bulk velocity  

Science Journals Connector (OSTI)

We consider a two-dimensional (2D) stationary stream of a collisionless plasma injected across an external stationary magnetic field and a background stagnant plasma. The solution is found by solving the Vlasov equation for each species (electrons and protons), the Maxwell-Ampere equation for the magnetic vector potential, and the equation of plasma quasineutrality for the electrostatic potential. The solution of the stationary Vlasov equation is given in terms of two constants of motion and one adiabatic invariant. The partial charge and current densities are given by analytical expressions of the moments of the velocity distribution functions for each particle species. The 2D distribution of the plasma bulk velocity, Vx(y,z), is roughly uniform inside the jet. There is no plasma bulk flow in the direction of the magnetic field. Inside the boundary layer interfacing the jet and the stagnant plasma, the bulk velocity has gradients (i.e., shears) in the direction parallel as well perpendicular to the magnetic field. The parallel component of this gradient, ??V?, produces a nonzero electric field component parallel to the magnetic field lines, E?B?0. The parallel electric field within the transition layer is a basic element allowing plasma elements to be transported across magnetic field lines in astrophysical systems as well as in laboratory experiments where plasmoids are injected across magnetic fields.

Marius M. Echim and Joseph F. Lemaire

2005-09-13T23:59:59.000Z

120

EFFECTS OF UNRESOLVED MAGNETIC FIELD ON Fe I 617.3 AND 630.2 nm LINE SHAPES  

SciTech Connect (OSTI)

The contribution of the quiet Sun to solar irradiance variability, either due to changes of the solar effective temperature or to the presence of unresolved magnetic field, is still poorly understood. In this study we investigate spectral line diagnostics that are sensitive to both temperature variations and the presence of small-scale unresolved magnetic features in these areas of the solar atmosphere. Specifically, we study the dependence on the magnetic flux density of three parameters describing the shape of two magnetically sensitive Fe I lines, at 630.2 nm and 617.3 nm, namely the line core intensity (IC), the FWHM, and the equivalent width (EQW). To this end we analyze observations of active region NOAA 11172, acquired with Interferometric Bidimensional Spectrometer at the Dunn Solar Telescope, as well as results from numerical synthesis. Our results show that IC is sensitive to both temperature and magnetic flux density variations, FWHM is mostly affected by magnetic field changes, and EQW is mostly sensitive to temperature. Variations of a few percent of the measured line parameters are found in observational data that were spatially degraded to represent quiet-Sun, disk-center, medium-resolution observations. It is therefore possible to disentangle magnetic from pure thermodynamic effects by the comparison of temporal variations of the EQW and the FWHM of either of the two Fe I lines.

Criscuoli, S.; Ermolli, I.; Giorgi, F. [INAF-Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monte Porzio Catone (Italy)] [INAF-Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monte Porzio Catone (Italy); Uitenbroek, H. [National Solar Observatory, Sacramento Peak, P.O. Box 62, Sunpsot, NM 88349 (United States)] [National Solar Observatory, Sacramento Peak, P.O. Box 62, Sunpsot, NM 88349 (United States)

2013-02-15T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic field lines" 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

Singular lines of one-dimensional force-free magnetic field  

Science Journals Connector (OSTI)

The behavior of adiabatically slow deformations of the force-free field is investigated. Using the linear approximation it ... of boundary perturbations of one-dimensional force-free field there appear singular magnetic

N. A. Bobrova; S. I. Syrovatskii

1979-03-01T23:59:59.000Z

122

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

123

Tokamap:?A Hamiltonian twist map for magnetic field lines in a toroidal geometry  

Science Journals Connector (OSTI)

A Hamiltonian twist map (tokamap) is constructed as a representation of the stroboscopic plot of magnetic field lines in a toroidal confinement device as used in fusion physics. This “tokamap” is compatible with minimal toroidal geometry requirements (in particular, the polar axis cannot be crossed upon iteration). It depends on two parameters: the stochasticity parameter K and the winding number on axis, w. With increasing values of K, chaotic regions appear mostly near the edge of the torus, while the zone near the magnetic axis remains very robust. The number and nature of the fixed points are studied in detail, as they determine the appearance of the phase portraits near the axis. It is shown that the topology undergoes several bifurcations as K and/or w are varied. The various phase portraits reproduce the qualitative features known in tokamak physics. The time series exhibit a typical behavior describable by a continuous time random walk, as found in previous works on the standard map.

R. Balescu; M. Vlad; F. Spineanu

1998-07-01T23:59:59.000Z

124

Transmission Line MTF: Magnetized Target Fusion  

E-Print Network [OSTI]

Transmission Line MTF: Magnetized Target Fusion Initial target: preheated & magnetized Subsequent for the FRC. Abstract Block Diagram theta coil transmission line Bias cap. bank maincapacitor inductor PI cap compression to fusion conditions Magnetic field of at least 5 T in a closed-field line topology Density ~ 1017

125

Magnetic-field induced absorption of zero-phonon lines in tris(bipyridine)ruthenium(2+) bis(hexafluorophosphate) and diperchlorate single crystals  

Science Journals Connector (OSTI)

Magnetic-field induced absorption of zero-phonon lines in tris(bipyridine)ruthenium(2+) bis(hexafluorophosphate) and diperchlorate single crystals ...

G. Hensler; E. Gallhuber; H. Yersin

1987-06-01T23:59:59.000Z

126

The splitting of hyperfine lines of57Fe nuclei in RF magnetic field  

Science Journals Connector (OSTI)

It is shown experimentally, that for Moessbauer nuclei affected by the radio-frequency (RF) magnetic field of sufficient intensity at frequencies corresponding to ... occurs. Depending on the frequency of alterna...

F. G. Vagizov

1990-08-01T23:59:59.000Z

127

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

128

Diagnosis of Magnetic and Electric Fields of Chromospheric Jets through Spectropolarimetric Observations of HI Paschen Lines  

E-Print Network [OSTI]

Magnetic fields govern the plasma dynamics in the outer layers of the solar atmosphere, and electric fields acting on neutral atoms that move across the magnetic field enable us to study the dynamical coupling between neutrals and ions in the plasma. In order to measure the magnetic and electric fields of chromospheric jets, the full Stokes spectra of the Paschen series of neutral hydrogen in a surge and in some active region jets that took place at the solar limb were observed on May 5, 2012, using the spectropolarimeter of the Domeless Solar Telescope at Hida observatory, Japan. First, we inverted the Stokes spectra taking into account only the effect of magnetic fields on the energy structure and polarization of the hydrogen levels. Having found no definitive evidence of the effects of electric fields in the observed Stokes profiles, we then estimated an upper bound for these fields by calculating the polarization degree under the magnetic field configuration derived in the first step, with the additional ...

Anan, Tetsu; Ichimoto, Kiyoshi

2014-01-01T23:59:59.000Z

129

Divergence of Neighboring Magnetic-Field Lines and Fast-Particle Diffusion in Strong Magnetohydrodynamic Turbulence, with Application to Thermal Conduction in Galaxy Clusters  

Science Journals Connector (OSTI)

Using direct numerical simulations, we calculate the rate of divergence of neighboring magnetic-field lines in different types of strong magnetohydrodynamic turbulence. In the static-magnetic-field approximation, our results imply that tangled magnetic fields in galaxy clusters reduce the electron diffusion coefficient and thermal conductivity by a factor of ?5–10, relative to their values in a nonmagnetized plasma.

Jason Maron; Benjamin D. G. Chandran; Eric Blackman

2004-01-27T23:59:59.000Z

130

A note on the magnetic field topology in the vicinity of neutral points in the resistive MHD and collisionless plasma approximations; Geometry of field-lines in the geomagnetic tail  

Science Journals Connector (OSTI)

The ‘sweeping’ effect and the convection of field-lines in the geomagnetic tail explain the magnetic field observations in tailward flowing plasmas at substorm...

A. Hruška

131

Force-free magnetosphere of an aligned rotator with differential rotation of open magnetic field lines  

Science Journals Connector (OSTI)

Here we briefly report on results of self-consistent numerical modeling of a differentially rotating force-free magnetosphere of an aligned rotator. We show that differential rotation of the open field line z...

A. N. Timokhin

2007-01-01T23:59:59.000Z

132

Force-free magnetosphere of an aligned rotator with differential rotation of open magnetic field lines  

Science Journals Connector (OSTI)

Here we briefly report on results of self-consistent numerical modeling of a differentially rotating force-free magnetosphere of an aligned rotator. We show that differential rotation of the open field line z...

A. N. Timokhin

2007-04-01T23:59:59.000Z

133

Potential Structure Modified by Electron Cyclotron Resonance in a Plasma Flow along Magnetic Field Lines with Mirror Configuration  

Science Journals Connector (OSTI)

A plasma potential structure is modified by the electron cyclotron resonance (ECR) in a collisionless plasma flow along magnetic field lines with simple mirror configuration. In the presence of a single ECR point at the bottom of the magnetic well, there appears a potential dip (thermal barrier) around this point, being followed by a potential hump (plug potential) in the downstream side. The result in this simplified configuration gives a clear-cut physics to the formation of field-aligned plug potential with thermal barrier.

T. Kaneko; R. Hatakeyama; N. Sato

1998-03-23T23:59:59.000Z

134

Magnetically insulated transmission line oscillator  

DOE Patents [OSTI]

A magnetically insulated transmission line oscillator employs self-generated magnetic fields to generate microwave energy. An anode of the oscillator includes slow-wave structures which are formed of a plurality of thin conductive vanes defining cavities therebetween, and a gap is formed between the anode and a cathode of the oscillator. In response to a pulsed voltage applied to the anode and cathode, self-generated magnetic fields arfe produced in a cross-field orientation with respect to the orientation of the electric field between the anode and the cathode. The cross-field magnetic fields insulate the flow of electrons in the gap and confine the flow of electrons within the gap.

Bacon, Larry D. (Albuquerque, NM); Ballard, William P. (Albuquerque, NM); Clark, M. Collins (Albuquerque, NM); Marder, Barry M. (Albuquerque, NM)

1988-01-01T23:59:59.000Z

135

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...

136

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

137

The Millennium Arecibo 21-cm Absorption Line Survey. IV. Statistics of Magnetic Field, Column Density, and Turbulence  

E-Print Network [OSTI]

We discuss observations of the magnetic field, column density, and turbulence in the Cold Neutral Medium (CNM). The observed quantities are only indirectly related to the intrinsic astronomical ones. We relate the observed and intrinsic quantities by relating their univariate and bivariate probability distribution functions (pdfs). We find that observations of the line-of-sight component of magnetic field do not constrain the pdf of the total field very well, but do constrain the median value of the total field. In the CNM, we find a well-defined median magnetic field 6.0 +/-1.8 microGauss. The CNM magnetic field dominates thermal motions. Turbulence and magnetism are in approximate equipartition. We find the probability distribution of HI column density Nperp in the sheets closely follows Nperp^-1 over a range of two orders of magnitude, 0.026 < Nperp < 2.6 (times 10^20 cm^-2). The bivariate distributions are not well enough determined to constrain structural models of CNM sheets.

Carl Heiles; T. H. Troland

2005-01-21T23:59:59.000Z

138

Why an ac Magnetic Field Shifts the Irreversibility Line in Type-II Superconductors  

Science Journals Connector (OSTI)

We show that for a thin superconducting strip placed in a transverse dc magnetic field—the typical geometry of experiments with high- Tc superconductors—the application of a weak ac magnetic field perpendicular to the dc field generates a dc voltage in the strip. This voltage leads to the decay of the critical currents circulating in the strip, and eventually the equilibrium state of the superconductor is established. This relaxation is not due to thermally activated flux creep but to the “walking” motion of vortices in the two-dimensional critical state of the strip with in-plane ac field. Our theory explains the shaking effect that was used for detecting phase transitions of the vortex lattice in superconductors.

Ernst Helmut Brandt and Grigorii P. Mikitik

2002-06-20T23:59:59.000Z

139

The iron $K_?$ lines as a tool for magnetic field estimations in non-flat accretion flows  

E-Print Network [OSTI]

Observations of AGNs and microquasars by ASCA, RXTE, Chandra and XMM-Newton indicate the existence of broad X-ray emission lines of ionized heavy elements in their spectra. Such spectral lines were discovered also in X-ray spectra of neutron stars and X-ray afterglows of GRBs. Recently, Zakharov et al. (MNRAS, 2003, 342, 1325) described a procedure to estimate an upper limit of the magnetic fields in regions from which X-ray photons are emitted. The authors simulated typical profiles of the iron $K_\\alpha$ line in the presence of magnetic field and compared them with observational data in the framework of the widely accepted accretion disk model. Here we further consider typical Zeeman splitting in the framework of a model of non-flat accretion flows, which is a generalization of previous consideration into non-equatorial plane motion of particles emitting X-ray photons. Using perspective facilities of space borne instruments (e.g. Constellation-X mission) a better resolution of the blue peak structure of iron $K_\\alpha$ line will allow to evaluate the magnetic fields with higher accuracy.

A. F. Zakharov; Z. Ma; Y. Bao

2004-11-22T23:59:59.000Z

140

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

Note: This page contains sample records for the topic "magnetic field lines" 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

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...

142

Polarization of absorption lines as a diagnostics of circumstellar, interstellar and intergalactic magnetic fields: Fine structure atoms  

E-Print Network [OSTI]

The relative population of the fine structure sublevels of an atom's ground state is affected by radiative transitions induced by an anisotropic radiation flux. This causes the alignment of atomic angular momentum. In terms of observational consequences for the interstellar and intergalactic medium, this results in the polarization of the absorption lines. In the paper we consider the conditions necessary for this effect and provide calculations of polarization from a few astrophysically important atoms and ions with multiple upper and lower levels for an arbitrary orientation of magnetic fields to the a) source of optical pumping, b) direction of observation, c) absorbed source. We also consider an astrophysically important ``degenerate'' case when the source of optical pumping coincides with the source of the absorbed radiation. We present analytical expressions that relate the degree of linear polarization and the intensity of absorption to the 3D orientation of the magnetic field with respect to the pumping source, the source of the absorbed radiation, and the direction of observations. We discuss how all these parameters can be determined via simultaneous observations of several absorption lines and suggest graphical means that are helpful in practical data interpretation. We prove that studies of absorption line polarization provide a unique tool to study 3D magnetic field topology in various astrophysical conditions.

Huirong Yan; A. Lazarian

2006-11-09T23:59:59.000Z

143

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

144

Parallel transport of long mean-free-path plasmas along open magnetic field lines: Plasma profile variation  

SciTech Connect (OSTI)

Parallel transport of long mean-free-path plasma along an open magnetic field line is characterized by strong temperature anisotropy, which is driven by two effects. The first is magnetic moment conservation in a non-uniform magnetic field, which can transfer energy between parallel and perpendicular degrees of freedom. The second is decompressional cooling of the parallel temperature due to parallel flow acceleration by conventional presheath electric field which is associated with the sheath condition near the wall surface where the open magnetic field line intercepts the discharge chamber. To the leading order in gyroradius to system gradient length scale expansion, the parallel transport can be understood via the Chew-Goldbeger-Low (CGL) model which retains two components of the parallel heat flux, i.e., q{sub n} associated with the parallel thermal energy and q{sub s} related to perpendicular thermal energy. It is shown that in addition to the effect of magnetic field strength (B) modulation, the two components (q{sub n} and q{sub s}) of the parallel heat flux play decisive roles in the parallel variation of the plasma profile, which includes the plasma density (n), parallel flow (u), parallel and perpendicular temperatures (T{sub Parallel-To} and T{sub Up-Tack }), and the ambipolar potential ({phi}). Both their profile (q{sub n}/B and q{sub s}/B{sup 2}) and the upstream values of the ratio of the conductive and convective thermal flux (q{sub n}/nuT{sub Parallel-To} and q{sub s}/nuT{sub Up-Tack }) provide the controlling physics, in addition to B modulation. The physics described by the CGL model are contrasted with those of the double-adiabatic laws and further elucidated by comparison with the first-principles kinetic simulation for a specific but representative flux expander case.

Guo Zehua; Tang Xianzhu [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2012-08-15T23:59:59.000Z

145

Ubiquity of chaotic magnetic-field lines generated by three-dimensionally crossed wires in modern electric circuits  

Science Journals Connector (OSTI)

We investigate simple three-dimensionally crossed wires carrying electric currents which generate chaotic magnetic-field lines (CMFLs). As such wire systems, cross-ring and perturbed parallel-ring wires are studied, since topologically equivalent configurations to these systems can often be found in contemporary electric and integrated circuits. For realistic fundamental wire configurations, the conditions for wire dimensions (size) and current values to generate CMFLs are numerically explored under the presence of the weak but inevitable geomagnetic field. As a result, it is concluded that CMFLs can exist everywhere; i.e., they are ubiquitous in the modern technological world.

M. Hosoda; T. Miyaguchi; K. Imagawa; K. Nakamura

2009-12-21T23:59:59.000Z

146

Survey of Magnetic Fields Near BPA 230-kV and 500-kV Transmission Lines.  

SciTech Connect (OSTI)

The purpose of this study was to characterize typical levels and variability of 60Hz magnetic fields at the centerline and edge of right-of-way of Bonneville Power Administration (BPA) 230-kV and 500-kV transmission lines. This was accomplished by taking magnetic field measurements at over 800 spans in Oregon and Washington. The spans were sampled using a stratified random sampling procedure with region (East vs. West), voltage (230-kV vs 500-kV), and circuit configuration as strata. There were five different circuit configuration groups for each region/voltage category requiring a total of 200 strata. Magnetic field measurements were taken at 13 locations under each span using an EMDEX-C as a survey meter. Additional information recorded for each span included conductor height (at 10 locations), right-of-way width, longitudinal and lateral slope, time of day, vegetation, terrain, weather conditions, temperature, wind speed, span length and presence of other lines in the corridor. 9 refs., 17 figs., 26 tabs.

Perrin, Nancy; Aggarwal, Rajinder Pal; Bracken, T. Daniel

1991-05-20T23:59:59.000Z

147

The divergence of neighboring magnetic field lines and fast-particle diffusion in strong magnetohydrodynamic turbulence, with application to thermal conduction in galaxy clusters  

E-Print Network [OSTI]

We investigate field-line separation in strong MHD turbulence using direct numerical simulations. We find that in the static-magnetic-field approximation the thermal conductivity in galaxy clusters is reduced by a factor of about 50 relative to the Spitzer thermal conductivity of a non-magnetized plasma. This value is too small for heat conduction to balance radiative cooling in clusters.

Jason L. Maron; Benjamin D. G. Chandran; Eric G. Blackman

2003-03-11T23:59:59.000Z

148

High-Harmonic Fast-Wave Power Flow along Magnetic Field Lines in the Scrape-Off Layer of NSTX  

Science Journals Connector (OSTI)

A significant fraction of high-harmonic fast-wave (HHFW) power applied to NSTX can be lost to the scrape-off layer (SOL) and deposited in bright and hot spirals on the divertor rather than in the core plasma. We show that the HHFW power flows to these spirals along magnetic field lines passing through the SOL in front of the antenna, implying that the HHFW power couples across the entire width of the SOL rather than mostly at the antenna face. This result will help guide future efforts to understand and minimize these edge losses in order to maximize fast-wave heating and current drive.

R. J. Perkins; J. C. Hosea; G. J. Kramer; J.-W. Ahn; R. E. Bell; A. Diallo; S. Gerhardt; T. K. Gray; D. L. Green; E. F. Jaeger; M. A. Jaworski; B. P. LeBlanc; A. McLean; R. Maingi; C. K. Phillips; L. Roquemore; P. M. Ryan; S. Sabbagh; G. Taylor; J. R. Wilson

2012-07-27T23:59:59.000Z

149

High-Harmonic Fast-Wave Power Flow Along Magnetic Field Lines in the Scrape-Off Layer of NSTX  

SciTech Connect (OSTI)

A significant fraction of high-harmonic fast-wave (HHFW) power applied to NSTX can be lost to the scrape-off layer (SOL) and deposited in bright and hot spirals on the divertor rather than in the core plasma. We show that the HHFW power flows to these spirals along magnetic field lines passing through the SOL in front of the antenna, implying that the HHFW power couples across the entire width of the SOL rather than mostly at the antenna face. This result will help guide future efforts to understand and minimize these edge losses in order to maximize fast-wave heating and current drive.

Perkins, R. J. [Princeton Plasma Physics Laboratory (PPPL); Hosea, J. [Princeton Plasma Physics Laboratory (PPPL); Kramer, G. [Princeton Plasma Physics Laboratory (PPPL); Ahn, Joonwook [ORNL; Bell, R. E. [Princeton Plasma Physics Laboratory (PPPL); Diallo, A. [Princeton Plasma Physics Laboratory (PPPL); Gerhardt, S. [Princeton Plasma Physics Laboratory (PPPL); Gray, T. K. [Oak Ridge National Laboratory (ORNL); Green, David L [ORNL; Jaeger, Erwin Frederick [ORNL; Jaworski, M. A. [Princeton Plasma Physics Laboratory (PPPL); LeBlanc, B [Princeton Plasma Physics Laboratory (PPPL); McLean, Adam G [ORNL; Maingi, Rajesh [ORNL; Phillips, C. K. [Princeton Plasma Physics Laboratory (PPPL); Roquemore, L. [Princeton Plasma Physics Laboratory (PPPL); Ryan, Philip Michael [ORNL; Sabbagh, S. A. [Columbia University; Taylor, G. [Princeton Plasma Physics Laboratory (PPPL); Wilson, J. R. [Princeton Plasma Physics Laboratory (PPPL)

2012-01-01T23:59:59.000Z

150

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...

151

Magnetic field exposure assessment for adult residents of Maine who live near and far away from overhead transmission lines  

SciTech Connect (OSTI)

Sixty-Hz magnetic field exposures were measured for 45 adult residents of Maine. Thirty of the subjects resided near rights-of-way (ROWs) with either 345- and 115-kV transmission lines, or ROWs with only 115-kV transmission lines; fifteen resided far from any transmission lines. Personal exposure data for a single 24-hour period was acquired with the EMDEX. The EMDEX's event-marker button was used to partition exposures into Home and Away components. Also, three area measurements were taken for each subject during the personal exposure measurement period: (1) 24-hr fixed-site bedroom measurement with a second EMDEX; (2) Spot measurements in at least three rooms of every residence; and (3) Spot measurements outside each residence. Residence near transmission lines highly loaded during the measurement period was associated with increased Home and Total exposure relative to a far-away population. Average exposure level while away from home was uniform (at about 2 mG) throughout the study population. On a quantitative level, Home exposure was correlated equivalently with Spot-In (r = .70) and the 24-hr fixed site measurement (r = .68). Correlations of area measurements with Total exposure were weaker because of the dilution effect of Away exposure (r = .64 for Spot-In; r = .61 for 24-h Bedroom). Away and Home exposures were not correlated (r = .14), which reinforced our confidence that the participants used the EMDEX correctly. The data suggest the need for caution before inferences are drawn about total personal exposure from area measurements. The study demonstrates the feasibility of obtaining valid measures of magnetic-field exposure with the personal exposure monitors that have been developed.

Kavet, R.; Silva, J.M.; Thornton, D. (Enertech Consultants, Campbell, CA (United States))

1992-01-01T23:59:59.000Z

152

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,...

153

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

154

Ribbons characterize magnetohydrodynamic magnetic fields better than lines: a lesson from dynamo theory  

Science Journals Connector (OSTI)

......and the schematic diagram exemplifies a general...discs|dynamo|MHD|stars: magnetic...cannot be correct for MHD at large R M which...Therefore, this diagram does not account...magnetic helicity in MHD dynamos for a large...The associated diagram of the alpha2 dynamo......

Eric G. Blackman; Alexander Hubbard

2014-01-01T23:59:59.000Z

155

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

156

The magnetic sun from different views: A comparison of the mean and background magnetic field observations made in different observatories and in different spectral lines  

Science Journals Connector (OSTI)

A comparison is made of observational data on the mean magnetic field of the Sun from several observatories (a ... correlation and regression analyses of observations of background magnetic fields at the STOP tel...

M. L. Demidov

157

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

158

Enhancement of spectral intensities of mercury triplet lines in longitudinal magnetic field  

Science Journals Connector (OSTI)

The variation of intensity of the spectral lines of the triplet series of mercury namely...3 S 1 ? 63 P 012) (?5461 Å,? 4358 Å,?...4047 Å) in the pr...

S N Sen; S K Sadhya

1986-03-01T23:59:59.000Z

159

Magnetic Field Line Transport in Anisotropic Magnetic Turbulence: Anomalous, Quasilinear, and Percolative Regimes Versus the Kubo Number  

Science Journals Connector (OSTI)

The transport of plasma and of energetic particles because of magnetic turbulence is relevant to many space plasmas, ranging from the planetary magnetospheres to the solar corona and to the heliosphere. Variou...

Gaetano Zimbardo; Pierluigi Veltri; Pierre Pommois

160

Evaluation of Low-Field Nuclear Magnetic Resonance Spectrometry for At-Line Process Analysis  

Science Journals Connector (OSTI)

A low-field medium-resolution NMR spectrometer, with an operating frequency of 29 MHz for 1H, has been developed for use in process analysis. The information that is...

Nordon, Alison; McGill, Colin A; Littlejohn, David

2002-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic field lines" 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

Nodal Lines of Normal Components of Scattered Fields on Surfaces of Boiler Pipelines with Arbitrary Positions of Flawed Areas with Respect to External Magnetic Field Perpendicular to Their Axes  

Science Journals Connector (OSTI)

The paper reports on an investigation of the effect of a awed area configuration with respect to an applied weak magnetic field perpendicular to the pipe axis on the pattern of nodal lines of the resulting normal...

V. G. Kuleev; A. A. Dubov; V. V. Lopatin

2002-01-01T23:59:59.000Z

162

Effect of magnetic field with helical lines of force on the capillary instability of magnetic fluids with the interface surrounding a current-carrying conductor  

Science Journals Connector (OSTI)

The subject of investigation is a configuration made up of immiscible magnetic fluids surrounding a long current-carrying conductor in the presence of an external longitudinal magnetic field. The axisymmetric ...

V. M. Korovin

2006-08-01T23:59:59.000Z

163

Vortex lines in films: Fields and interactions  

Science Journals Connector (OSTI)

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

Gilson Carneiro and Ernst Helmut Brandt

2000-03-01T23:59:59.000Z

164

Study of atomic spectral lines in a magnetic field with use of a nanocell with the thickness L = ?  

Science Journals Connector (OSTI)

We propose a technique which we call “L = ? Zeeman technique” (LZT) for investigation of the transitions between the Zeeman sublevels of the hfs structure of alkali metal atoms in external magnetic fields. The te...

T. S. Varzhapetyan; G. T. Hakhumyan…

2007-12-01T23:59:59.000Z

165

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

166

Effects of diffusion and surface interactions on the line shape of electron paramagnetic resonances in the presence of a magnetic field gradient  

Science Journals Connector (OSTI)

In an evanescent wave magnetometer the Zeeman polarization is probed at micrometer to submicrometer distances from the cell surface. The electron paramagnetic resonance lines of an evanescent wave magnetometer in the presence of a magnetic field gradient exhibit edge enhancement seen previously in nuclear magnetic resonance lines. We present a theoretical model that describes quantitatively the shape of the magnetic resonance lines of an evanescent wave magnetometer under a wide range of experimental conditions. It accounts for diffusion broadening in the presence of a magnetic field gradient as well as interactions of spin polarized Rb atoms with the coated Pyrex glass surfaces. Depending on the field gradient, cell thickness, and buffer gas pressure, the resonance line may have the form of a single asymmetric peak or two peaks localized near the front and back surfaces in frequency space. The double-peaked response depends on average characteristics of the surface interactions. Its shape is sensitive to the dwell time, relaxation probability, and average phase shift of adsorbed spin polarized Rb atoms.

M. Schaden; K. F. Zhao; Z. Wu

2007-12-07T23:59:59.000Z

167

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

168

A technical note about Phidel: a new software for evaluating magnetic induction field generated by power lines  

Science Journals Connector (OSTI)

......measurements collected near two 380 kV power lines(10) (Figure 7) using the LINDA system, made by an EMDEX II field meter (by Enertech Consultants) fixed on a mobile support, supplied with an odometer. This simultaneously records the field values, the time......

M. Comelli; M. Benes; A. Bampo; R. Villalta

2007-02-01T23:59:59.000Z

169

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

170

FIGURE 1. Simulation results for stationary MHD outflow obtained using a spherical coordinate system (Ustyugova et al. 1999). The solid lines represent the poloidal magnetic field, and the arrows  

E-Print Network [OSTI]

coordinate system (Ustyugova et al. 1999). The solid lines represent the poloidal magnetic field, and the arrows the velocity vectors. The dashed lines in the left-hand plot represent the slow magnetosonic surface (the lowest dashed line), the Alfvén surface (the middle line), and the fast magnetosonic surface

171

On the influence of a magnetic field with circular field lines on the gravity flow of a magnetic fluid film down a thin cylinder  

Science Journals Connector (OSTI)

The gravity-induced flow of a magnetic fluid film down a vertical thin current-carrying cylindrical conductor is considered. The relative thickness of the film is small. A nonlinear equation is derived from a ...

V. M. Korovin

2009-10-01T23:59:59.000Z

172

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

173

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

174

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.

175

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

176

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

177

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

178

The Effect of Magnetic Field Tilt and Divergence on the Mass Flux and Flow Speed in a Line-Driven Stellar Wind  

E-Print Network [OSTI]

We carry out an extended analytic study of how the tilt and faster-than-radial expansion from a magnetic field affect the mass flux and flow speed of a line-driven stellar wind. A key motivation is to reconcile results of numerical MHD simulations with previous analyses that had predicted non-spherical expansion would lead to a strong speed enhancement. By including finite-disk correction effects, a dynamically more consistent form for the non-spherical expansion, and a moderate value of the line-driving power index $\\alpha$, we infer more modest speed enhancements that are in good quantitative agreement with MHD simulations, and also are more consistent with observational results. Our analysis also explains simulation results that show the latitudinal variation of the surface mass flux scales with the square of the cosine of the local tilt angle between the magnetic field and the radial direction. Finally, we present a perturbation analysis of the effects of a finite gas pressure on the wind mass loss rate and flow speed in both spherical and magnetic wind models, showing that these scale with the ratio of the sound speed to surface escape speed, $a/v_{esc}$, and are typically 10-20% compared to an idealized, zero-gas-pressure model.

Stan Owocki; Asif ud-Doula

2003-10-07T23:59:59.000Z

179

> FOR CONFERENCE-RELATED PAPERS, REPLACE THIS LINE WITH YOUR SESSION NUMBER, E.G., AB-02 (DOUBLE-CLICK HERE) Magnetic Field in Internal  

E-Print Network [OSTI]

-CLICK HERE) Magnetic Field in Internal and External Rotor model for the computation of magnetic field distribution in any number of stator slots and rotor poles on subdomain model for predicting magnetic field in any FSM topology with defining in advance the number

Boyer, Edmond

180

Spectral line broadening in magnetized black holes  

E-Print Network [OSTI]

We consider weakly magnetized non-rotating black holes. In the presence of a regular magnetic field the motion of charged particles in the vicinity of a black hole is modified. As a result, the position of the innermost stable circular orbit (ISCO) becomes closer to the horizon. When the Lorentz force is repulsive (directed from the black hole) the ISCO radius can reach the gravitational radius. In the process of accretion charged particles (ions) of the accreting matter can be accumulated near their ISCO, while neutral particles fall down to the black hole after they reach $6M$ radius. The sharp spectral line Fe K$\\alpha$, emitted by iron ions at such orbits, is broadened when the emission is registered by a distant observer. In this paper we study this broadening effect and discuss how one can extract information concerning the strength of the magnetic field from the observed spectrum.

Valeri P. Frolov; Andrey A. Shoom; Christos Tzounis

2014-05-02T23:59:59.000Z

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


181

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 ...

182

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

183

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

184

Axial power loss along open field lines  

SciTech Connect (OSTI)

Studies are underway to evaluate the linear mirror geometry as a candidate for a high-fluence, neutron irradiation facility. This steady-state, low-Q design is currently perceived to comprise a two-component plasma driven by neutral beams with mirror confinement of the hot ions and with no electrostatic axial reduction in the warm ion end losses. Warm-ion fueling and end-wall power density will require substantial cold plasma exterior to the mirror cell and neutral gas near the end wall. In this paper, we evaluate to what extent the loss power parallel to the axial magnetic field along open field lines is a function of the escaping plasma and end-wall parameters. By allowing the source power to depend directly on the plasma density and electron temperature, several new conclusions may be pertinent to closed field-line geometries with open field-line divertors.

Correll, D.L.

1987-08-01T23:59:59.000Z

185

How Does the Distribution of External Magnetic Lines of Force Influence the Growth of Ferromagnetic Material?  

Science Journals Connector (OSTI)

As one of the most important ferromagnetic materials, nickel shows applications in many fields including catalysis,(15) magnet sensors,(16) magnetic recording media,(17) conduction materials,(18) and ferrofluids. ... When an external magnetic field is applied, the directions of the self-generated magnetic fields could be adjusted to be the same by the external magnetic field, conducing one-dimensional structures along the external magnetic lines of force. ... Since these quasi-one-dimensional magnets are parallel to each other, the interaction caused by the self-generated magnetic fields between the quasi-one-dimensional magnets which are aligned in different magnetic lines of force could be ignored. ...

Rui-Ping Ji; Ji-Sen Jiang; Ming Hu

2010-06-28T23:59:59.000Z

186

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...

187

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

188

The Influence of Stochastic Layers of Magnetic Field Lines on Transport Barrier Formation in a Stellarator System  

Science Journals Connector (OSTI)

The results of local measurements of RF discharge plasma parameters in the process of internal transport barriers (ITB) formation in the vicinity of rational magnetic surfaces in the Uragan-3M torsatron are ... o...

E.D. Volkov; V.L. Berezhnyi; V.N. Bondarenko…

2003-10-01T23:59:59.000Z

189

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

Science Journals Connector (OSTI)

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

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

2008-03-21T23:59:59.000Z

190

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

191

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...

192

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

193

Critical lines of magnetic semiconductor thin films: Experiment  

Science Journals Connector (OSTI)

The irreversibilities between the field-cooled and zero-field-cooled dc magnetization were used to determine the field and composition dependence of the spin-glass freezing temperature in CdCr2-2x In2x Se4 thin films. The magnetic ordering was confirmed by the temperature dependence of induced magnetization M and unidirectional magnetic anisotropy field Han determined from ferromagnetic resonance data (4.2–120 K). The experimentally determined H-T phase diagram shows two instability lines: the Gabay-Toulouse-type (GT line) and the Almeida-Thouless-type (AT line) for thin films of CdCr2 Se4 :In with reentrant transition and the AT line for CdCr2-2x In2x Se4 in the spin-glass state. The AT and GT lines obey the relation ?=[(n+1)(n+2)/8]1/3 (heff )2/3 and ?=[(n2 +4n+2)/(4(n+2)2 )] (heff )2 , respectively, for the normalized effective field heff =ha +hm . The first term in heff stands for the external magnetic field, while the second is related to the internal field of the infinite ferromagnetic network (long-range ordering). The value of hm determined from the H-T phase diagram was found to be dependent on indium concentration.

M. Lubecka; L. J. Maksymowicz; R. Szymczak; W. Powroz-acutenik

1997-03-01T23:59:59.000Z

194

Containment of an adiabatic plasma on magnetic lines of force by a self-generated electrostatic field  

Science Journals Connector (OSTI)

One component of a three-fluid adiabatic plasma is under certain conditions contained in a restricted region of space by a large-scale electrostatic field generated within the plasma. The containment is discus...

A. Hruška

195

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

196

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

197

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

198

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

199

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

200

Magnetic error analysis of recycler pbar injection transfer line  

SciTech Connect (OSTI)

Detailed study of Fermilab Recycler Ring anti-proton injection line became feasible with its BPM system upgrade, though the beamline has been in existence and operational since year 2000. Previous attempts were not fruitful due to limitations in the BPM system. Among the objectives are the assessment of beamline optics and the presence of error fields. In particular the field region of the permanent Lambertson magnets at both ends of R22 transfer line will be scrutinized.

Yang, M.J.; /Fermilab

2007-06-01T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic field lines" 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

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

202

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...

203

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

204

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

205

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

206

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

207

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

208

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

209

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

210

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

211

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.

212

Transferrin Binding to Two Human Colon Carcinoma Cell Lines: Characterization and Effect of 60-Hz Electromagnetic Fields  

Science Journals Connector (OSTI)

...12-O-tetradecanoylphorbol-13-acetate. 6522 MAGNETIC FIELD AND c-fos EXPRESSION...from center (mm) Fig. 1. Distributions of magnetic field intensity along the center line of a permanent magnet; (a) at the surface...

Jerry L. Phillips; Loyce Rutledge; and Wendell D. Winters

1986-01-01T23:59:59.000Z

213

$Nb_{3}Al$ prototype conductor for the transmission line magnet  

E-Print Network [OSTI]

The Very Large Hadron Collider (VLHC), under consideration for construction at Fermilab in the next 1-2 decades, is a 100 TeV cm pp collider. A major cost driver is the magnet. R&D is underway on several possible magnet designs. A low-field (2T) superferric magnet, sometimes called a transmission line magnet, may be the most cost- effective route to the VLHC. Although NbTi is now the cheapest superconductor measured in cost/kA-meter, Nb/sub 3/Al has the potential advantage that it remains superconducting at higher temperature. It may be particularly suited to the single "turn" and long straight lengths of the transmission line design. The combination of the simple magnet design and the higher strain tolerance than e.g. Nb/sub 3/Sn allows a simple process of cable fabrication, reaction, and magnet assembly. This higher strain tolerance is an advantage for splicing in the field. Sumitomo Electric Industries is producing an Nb/sub 3/Al conductor for the Fermilab low-field magnet program. (9 refs).

Barzi, E; Malamud, E; Mazur, P O; Piekarz, H; Wake, M; Hayashi, K; Koganeya, M

1999-01-01T23:59:59.000Z

214

Limits on guiding center and gyrokinetic plasma models in 3D magnetic fields  

E-Print Network [OSTI]

the motion into fast gyration around magnetic field lines and a slowly varying GC motion, with particle gyrofrequency (/t)/ . · Gyroangle defined in local orthogonal coordinates tied to the magnetic field lines, a globally consistent definition may not exist! · In 2D slab (straight, uniform magnetic field lines

215

RKKY interaction between extended magnetic defect lines in graphene  

Science Journals Connector (OSTI)

Of fundamental interest in the field of spintronics is the mechanism of indirect exchange coupling between magnetic impurities embedded in metallic hosts. A range of physical features, such as magnetotransport and overall magnetic moment formation, are predicated upon this magnetic coupling, often referred to as the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. Recent theoretical studies on the RKKY in graphene have been motivated by possible spintronic applications of magnetically doped graphene systems. In this paper a combination of analytic and numerical techniques are used to examine the effects of defect dimensionality on such an interaction. We show, in a mathematically transparent manner, that moving from single magnetic impurities to extended lines of impurities effectively reduces the dimensionality of the system and increases the range of the interaction. This has important consequences for the spintronic application of magnetically-doped systems, and we illustrate this with a simple magnetoresistance device.

P. D. Gorman; J. M. Duffy; S. R. Power; M. S. Ferreira

2014-09-08T23:59:59.000Z

216

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

217

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

218

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...

219

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

220

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

Note: This page contains sample records for the topic "magnetic field lines" 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

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

222

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

223

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,...

224

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

225

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

226

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

227

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......

228

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...

229

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

230

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

231

Exposure to Magnetic Fields and Survival after Diagnosis of Childhood Leukemia: A German Cohort Study  

Science Journals Connector (OSTI)

...distribution of field lines from sources placed below. The field magnitudes from...and measure its magnetic moment. To determine...dependence of the magnetic field amplitudes with a single magnetic dipole model...to human cell lines in vitro To evaluate...

Anne Louise Svendsen; Thomas Weihkopf; Peter Kaatsch; and Joachim Schüz

2007-06-01T23:59:59.000Z

232

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

233

Effect of demagnetization on magnetic resonance line shapes in bulk samples: Application to tungsten  

Science Journals Connector (OSTI)

A calculation of the contribution of a bulk specimen's nonuniform demagnetizing field to the inhomogeneous broadening of magnetic resonance lines is described. Demagnetization effects are of particular importance for substances with large bulk magnetic susceptibilities located in large static magnetic fields. Application is made to the nuclear acoustic resonance of W183 spins in a bulk cylindrical specimen of tungsten. In addition to explaining the observed inhomogeneous line broadening, the calculation predicts a "satellite" line which is also observed experimentally. Although attention is paid to specifically acoustic considerations, the calculation is applicable to magnetic resonance in general.

George Mozurkewich; H. I. Ringermacher; D. I. Bolef

1979-07-01T23:59:59.000Z

234

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...

235

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

236

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

237

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

238

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

239

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

240

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

Note: This page contains sample records for the topic "magnetic field lines" 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 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

242

Cyclotron harmonic lines in magnetic fluctuations of spiralling electrons in plasmas  

Science Journals Connector (OSTI)

The magnetic fluctuation spectrum in a magnetoplasma containing energetic electrons is observed to exhibit many lines at the cyclotron harmonics (?=n?ce, n=1. . .15). It is shown that these fluctuations are neither due to cyclotron radiation nor due to velocity-space instabilities but due to coherent solenoidal fields produced by electron cyclotron orbits and excited by thermal fluctuations. Such line spectra, observed in discharges and beam-plasma systems, may be useful for precise magnetic field diagnostics in plasmas.

G. Golubyatnikov and R. L. Stenzel

1993-02-15T23:59:59.000Z

243

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

244

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

245

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

246

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

247

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

248

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

249

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

250

The Effect of Magnetic Field on the Performance of Low-Power Cylindrical Hall Thrusters  

E-Print Network [OSTI]

electron flow is generated by the divergent magnetic field lines. (a) (b) Fig. 1. (a) SchematicThe Effect of Magnetic Field on the Performance of Low-Power Cylindrical Hall Thrusters IEPC-2005 for scaling down. The effect of the magnetic field on the discharge characteristics and efficiency of the low

251

Routes to interchange mode turbulence and chaos in plasmas confined by a helical magnetic field  

E-Print Network [OSTI]

. The helical magnetic field lines introduce a periodicity condition for the flute modes in the verticalRoutes to interchange mode turbulence and chaos in plasmas confined by a helical magnetic field K in a laboratory plasma confined by a helical magnetic field [1], i.e. a toroidal plasma with a weak vertical

252

Atmospheres of RR Lyrae Stars: Hypersonic Shock waves, Helium line detection and Magnetic fields. A few spectra for George Preston on the occasion of his birthday  

E-Print Network [OSTI]

During intensive/comparative studies with Preston's spectroscopic works (1961, 1962, 1964 & 1965) on RR Lyrae atmospheric phenomena, I unexpectedly found the existence of hypersonic shock waves (Chadid 1996 & 2008), that are strongly connected with the turbulence amplification mechanism (Chadid 1996b) and the Blazhko modulation (1997). Here I will show how the hypersonic shocks are at the origin of helium line formation and connected with the helium emission and line doubling detected by Preston (2009, 2011). I will present new neutral and single ionized helium line data in the hypersonic Blazhko star S Arae. The He II appears as a weak emission and its origin is strongly connected with the hypersonic shock in S Arae. The shock is extremely strong and can reach a Mach number >30. The HeI lines first appear in emission, over ~2% of the pulsation period, followed by the HeI absorption doubling phenomenon occurring simultaneously with the neutral metallic absorption line phenomenon over ~8% of the pulsat...

Chadid, Merieme

2011-01-01T23:59:59.000Z

253

Lines of Circular Polarization in Electromagnetic Wave Fields  

Science Journals Connector (OSTI)

8 October 1983 research-article Lines of Circular Polarization in Electromagnetic Wave Fields J...free space possesses, in general, two families of singular lines ( lines) on which the transverse field is circularly polarized. The...

1983-01-01T23:59:59.000Z

254

Initial Simulation Results of Storm-Time Ring Current in a Self-Consistent Magnetic Field Model  

E-Print Network [OSTI]

this issue. We assume for simplicity a model for B such that magnetic field lines lie in meridional planesInitial Simulation Results of Storm-Time Ring Current in a Self-Consistent Magnetic Field Model S a strong and time-dependent perturbation of the magnetospheric magnetic field B, and this magnetic-field

Lyons, Larry

255

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

256

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

257

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

258

Calculation of electric field and audible noise from transmission lines with non-parallel conductors  

SciTech Connect (OSTI)

In order to investigate the feasibility of using new transmission line configurations with non-parallel conductors, for managing magnetic field in critical areas, techniques are needed to assess the effects of different three-dimensional line arrangements on other important design parameters. A new method for calculation of electric field and corona-generated audible noise from non-parallel conductors is described and implemented as a computer tool. This method uses linearly varying line charges to simulate charge distribution along the axial direction of the transmission line. New algorithms are developed for calculating electric field and audible noise due to non-uniform line charges and illustrated by examples of low magnetic field transmission line designs.

Liu, Y. [Virginia Tech, Blacksburg, VA (United States)] [Virginia Tech, Blacksburg, VA (United States); Zaffanella, L.E. [Enertech Consultants, Lee, MA (United States)] [Enertech Consultants, Lee, MA (United States)

1996-07-01T23:59:59.000Z

259

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

260

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...

Note: This page contains sample records for the topic "magnetic field lines" 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

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

262

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...

263

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...

264

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

265

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

266

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...

267

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

268

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

269

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

270

Induction of c-fos Gene Expression by Exposure to a Static Magnetic Field in HeLaS3 Cells  

Science Journals Connector (OSTI)

...Rutqvist L. E., Ahlbom A. Magnetic fields and breast cancer in Swedish adults residing near high-voltage power lines. Epidemiology, 9: 392-397...power-line frequency electric and magnetic fields. NIEHS Working Group Report...

Masahiro Hiraoka; Junji Miyakoshi; Yu P. Li; Bokshil Shung; Hiraku Takebe; and Mitsuyuki Abe

1992-12-01T23:59:59.000Z

271

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

272

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

273

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

274

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

275

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

276

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

277

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

278

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

279

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

280

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

Note: This page contains sample records for the topic "magnetic field lines" 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

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

282

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

283

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

284

Abstract B50: Supercooling under magnetic field can control the risk for malignant transformations of human pluripotent stem (iPS) cells  

Science Journals Connector (OSTI)

...supercooling under magnetic field (2 kHz...human iPS cell lines from adult...human iPS cell lines for the supercooling under magnetic field group in 1...supercooling under magnetic field group (p0...human iPS cell lines which carry...

Hisashi Moriauchi; Makoto Mihara; Raymond Chung; Yue Zhang; and Chifumi Sato

2011-09-15T23:59:59.000Z

285

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

286

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

287

THE ABRUPT CHANGES IN THE PHOTOSPHERIC MAGNETIC AND LORENTZ FORCE VECTORS DURING SIX MAJOR NEUTRAL-LINE FLARES  

SciTech Connect (OSTI)

We analyze the spatial and temporal variations of the abrupt photospheric magnetic changes associated with six major flares using 12 minute, 0.''5 pixel{sup -1} vector magnetograms from NASA's Helioseismic and Magnetic Imager instrument on the Solar Dynamics Observatory satellite. The six major flares occurred near the main magnetic neutral lines of four active regions, NOAA 11158, 11166, 11283, and 11429. During all six flares the neutral-line field vectors became stronger and more horizontal, in each case almost entirely due to strengthening of the horizontal field components parallel to the neutral line. In all six cases the neutral-line pre-flare fields were more vertical than the reference potential fields, and collapsed abruptly and permanently closer to potential-field tilt angles during every flare, implying that the relaxation of magnetic stress associated with non-potential tilt angles plays a major role during major flares. The shear angle with respect to the reference potential field did not show such a pattern, demonstrating that flare processes do not generally relieve magnetic stresses associated with photospheric magnetic shear. The horizontal fields became significantly and permanently more aligned with the neutral line during the four largest flares, suggesting that the collapsing field is on average more aligned with the neutral line than the pre-flare neutral-line field. The vertical Lorentz force had a large, abrupt, permanent downward change during each of the flares, consistent with loop collapse. The horizontal Lorentz force changes acted mostly parallel to the neutral line in opposite directions on each side, a signature of the fields contracting during the flare, pulling the two sides of the neutral line toward each other. The greater effect of the flares on field tilt than on shear may be explained by photospheric line-tying.

Petrie, G. J. D. [National Solar Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)

2012-11-01T23:59:59.000Z

288

Exposure of Sprague-Dawley Rats to a 50-Hertz, 100-?Tesla Magnetic Field for 27 Weeks Facilitates Mammary Tumorigenesis in the 7,12-Dimethylbenz[a]-anthracene Model of Breast Cancer  

Science Journals Connector (OSTI)

...E., Ahlbom A. Magnetic fields and breast cancer...high-voltage power lines. Epidemiology...responses in two lines of Sprague-Dawley...1199-1204, 1984. Magnetic field exposure increases...Dawley rats. | In line with the possible...

Susanne Thun-Battersby; Meike Mevissen; and Wolfgang Löscher

1999-08-01T23:59:59.000Z

289

Slip Line Field Applied To Deep Drawing  

Science Journals Connector (OSTI)

Slip Line Field is a numerical method applied for modelling plane?strain processes. This method has been successfully checked properly for sheet drawing. Flange deformation in deep drawing is considered without change in thickness. A drawing mechanical test has been developed in order to reproduce the flange stresses state in sheet strips with the rolling direction selected. The fundamentals of this test and some experimental results obtained from it have been presented previously in different Congresses. In this work an algorithm based on SLF has been implemented and theoretical results evaluated for different conditions. The algorithm have been applied to a mild DDQ steel and to a DDQ AISI 304 stainless steel. Theoretical and experimental results are compared. A good concordance in them has been found out under some conditions. One of the most important aspects is that it must not be considered tensile material properties but a modified behavior under multiaxial conditions.

V. Miguel; J. Benet; J. Coello; A. Calatayud; A. Martínez

2007-01-01T23:59:59.000Z

290

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

291

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,...

292

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

293

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

294

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

295

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

296

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...

297

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...

298

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

E-Print Network [OSTI]

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

Scott McGuire; Simon Catterall; Mark Bowick; Simeon Warner

2001-05-02T23:59:59.000Z

299

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

300

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

Note: This page contains sample records for the topic "magnetic field lines" 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

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

302

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...

303

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

304

SET/RESET PULSE CIRCUITS FOR MAGNETIC SENSORS AN-201 Honeywell's line of magnetoresistive permalloy sensors  

E-Print Network [OSTI]

SET/RESET PULSE CIRCUITS FOR MAGNETIC SENSORS AN-201 Honeywell's line of magnetoresistive permalloy be achieved by using Honeywell's unique on-chip current strap to set/reset the permalloy film. This technique about the zero field output. Honeywell has a patented on-chip current strap for performing this re

Kleinfeld, David

305

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

306

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

307

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

308

Commensurate-incommensurate transitions in magnetic bubble arrays with periodic line pinning  

Science Journals Connector (OSTI)

We report direct observations of commensurate-incommensurate phase transitions as a function of bubble concentration in a two-dimensional magnetic bubble array subject to periodic line pinning. The pinning lines consist of lithographically produced parallel permalloy bars. Temperature is simulated by an ac magnetic field. The structure function shows a smooth migration of Bragg peaks with density indicating a second order (or weakly first order) commensurate-incommensurate-commensurate transition as the local orientation of the array rotates continuously. We have also identified a commensurate smectic phase.

Junmin Hu and R. M. Westervelt

1997-01-01T23:59:59.000Z

309

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

310

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...

311

Observation of high-energy electrons accelerated by electrostatic waves propagating obliquely to a magnetic field  

Science Journals Connector (OSTI)

It is revealed in microwave-plasma interaction experiments that a large-amplitude electrostatic wave propagating obliquely to a magnetic field accelerates electrons strongly almost along the magnetic field lines via the process of Vp×B acceleration. The experimental results are in reasonable agreement with the theoretical prediction of Sugihara et al.

Yasushi Nishida and Naoyuki Sato

1987-08-10T23:59:59.000Z

312

Particles as Wilson lines of gravitational field  

E-Print Network [OSTI]

Since the work of Mac-Dowell-Mansouri it is well known that gravity can be written as a gauge theory for the de Sitter group. In this paper we consider the coupling of this theory to the simplest gauge invariant observables that is, Wilson lines. The dynamics of these Wilson lines is shown to reproduce exactly the dynamics of relativistic particles coupled to gravity, the gauge charges carried by Wilson lines being the mass and spin of the particles. Insertion of Wilson lines breaks in a controlled manner the diffeomorphism symmetry of the theory and the gauge degree of freedom are transmuted to particles degree of freedom.

L. Freidel; J. Kowalski--Glikman; A. Starodubtsev

2006-07-04T23:59:59.000Z

313

Primary beam steering due to field leakage from superconducting SHMS magnets  

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

Simulations of the magnetic fields from the Super High Momentum Spectrometer in Hall C at Thomas Jefferson National Accelerator Facility show significant field leakage into the region of the primary beam line between the target and the beam dump. Without mitigation, these remnant fields will steer the unscattered beam enough to limit beam operations at small scattering angles. Presented here are magnetic field simulations of the spectrometer magnets and a solution using optimal placement of a minimal amount of shielding iron around the beam line.

Moore, M.H.; Waidyawansa, B.P.; Covrig, S.; Carlini, R.; Benesch, J.

2014-11-01T23:59:59.000Z

314

Primary Beam Steering Due to Field Leakage from Superconducting SHMS Magnets  

E-Print Network [OSTI]

Simulations of the magnetic fields from the Super High Momentum Spectrometer in Hall C at Thomas Jefferson National Accelerator Facility show significant field leakage into the region of the primary beam line between the target and the beam dump. Without mitigation, these remnant fields will steer the unscattered beam enough to limit beam operations at small scattering angles. Presented here are magnetic field simulations of the spectrometer magnets and a solution using optimal placement of a minimal amount of shielding iron around the beam line.

Michael H. Moore; Buddhini P. Waidyawansa; Silviu Covrig; Roger Carlini; Jay Benesch

2014-06-30T23:59:59.000Z

315

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

316

Controlled generation of field squeezing with cold atomic clouds coupled to a superconducting transmission line resonator  

SciTech Connect (OSTI)

We propose an efficient method for controlled generation of field squeezing with cold atomic clouds trapped close to a superconducting transmission line resonator. It is shown that, based on the coherent strong magnetic coupling between the collective atomic spins and microwave fields in the transmission line resonator, two-mode or single-mode field squeezed states can be generated through coherent control on the dynamics of the system. The degree of squeezing and preparing time can be directly controlled through tuning the external classical fields. This protocol may offer a promising platform for implementing scalable on-chip quantum information processing with continuous variables.

Li Pengbo; Li Fuli [MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Department of Applied Physics, Xi'an Jiaotong University, Xi'an 710049 (China)

2010-03-15T23:59:59.000Z

317

Controlled generation of field squeezing with cold atomic clouds coupled to a superconducting transmission line resonator  

E-Print Network [OSTI]

We propose an efficient method for controlled generation of field squeezing with cold atomic clouds trapped close to a superconducting transmission line resonator. It is shown that, based on the coherent strong magnetic coupling between the collective atomic spins and microwave fields in the transmission line resonator, two-mode or single mode field squeezed states can be generated through coherent control on the dynamics of the system. The degree of squeezing and preparing time can be directly controlled through tuning the external classical fields. This protocol may offer a promising platform for implementing scalable on-chip quantum information processing with continuous variables.

Peng-Bo Li; Fu-Li Li

2010-02-26T23:59:59.000Z

318

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

319

Electromagnetic Dipole Radiation Fields, Shear-Free Congruences and Complex Center of Charge World Lines  

E-Print Network [OSTI]

We show that for asymptotically vanishing Maxwell fields in Minkowski space with non-vanishing total charge, one can find a unique geometric structure, a null direction field, at null infinity. From this structure a unique complex analytic world-line in complex Minkowski space that can be found and then identified as the complex center of charge. By ''sitting'' - in an imaginary sense, on this world-line both the (intrinsic) electric and magnetic dipole moments vanish. The (intrinsic) magnetic dipole moment is (in some sense) obtained from the `distance' the complex the world line is from the real space (times the charge). This point of view unifies the asymptotic treatment of the dipole moments For electromagnetic fields with vanishing magnetic dipole moments the world line is real and defines the real (ordinary center of charge). We illustrate these ideas with the Lienard-Wiechert Maxwell field. In the conclusion we discuss its generalization to general relativity where the complex center of charge world-line has its analogue in a complex center of mass allowing a definition of the spin and orbital angular momentum - the analogues of the magnetic and electric dipole moments.

Carlos N. Kozameh; Ezra T. Newman

2005-04-20T23:59:59.000Z

320

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 lines" 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

Fringe Field Effects on Bending Magnets, Derived for TRANSPORT/TURTLE  

E-Print Network [OSTI]

A realistic magnetic dipole has complex effects on a charged particle near the entrance and exit of the magnet, even with a constant and uniform magnetic field deep within the interior of the magnet. To satisfy Maxwell's equations, the field lines near either end of a realistic magnet are significantly more complicated, yielding non-trivial forces. The effects of this fringe field are calculated to first order, applying both the paraxial and thin lens approximations. We find that, in addition to zeroth order effects, the position of a particle directly impacts the forces in the horizontal and vertical directions.

Blitz, Sam

2013-01-01T23:59:59.000Z

322

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

323

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

324

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

325

VELOCITY AND MAGNETIC FIELD DISTRIBUTION IN A FORMING PENUMBRA  

SciTech Connect (OSTI)

We present results from the analysis of high-resolution spectropolarimetric and spectroscopic observations of the solar photosphere and chromosphere, obtained shortly before the formation of a penumbra in one of the leading polarity sunspots of NOAA active region 11490. The observations were performed at the Dunn Solar Telescope of the National Solar Observatory on 2012 May 28, using the Interferometric Bidimensional Spectrometer. The data set is comprised of a 1 hr time sequence of measurements in the Fe I 617.3 nm and Fe I 630.25 nm lines (full Stokes polarimetry) and in the Ca II 854.2 nm line (Stokes I only). We perform an inversion of the Fe I 630.25 nm Stokes profiles to derive magnetic field parameters and the line-of-sight (LOS) velocity at the photospheric level. We characterize chromospheric LOS velocities by the Doppler shift of the centroid of the Ca II 854.2 nm line. We find that, before the formation of the penumbra, an annular zone of 3''-5'' width is visible around the sunspot. In the photosphere, we find that this zone is characterized by an uncombed structure of the magnetic field although no visible penumbra has formed yet. We also find that the chromospheric LOS velocity field shows several elongated structures characterized by downflow and upflow motions in the inner and outer parts of the annular zone, respectively.

Romano, P.; Guglielmino, S. L. [INAF-Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95125 Catania (Italy); Frasca, D.; Zuccarello, F. [Dipartimento di Fisica e Astronomia-Sezione Astrofisica, Universita di Catania, Via S. Sofia 78, I-95125 Catania (Italy); Ermolli, I. [INAF-Osservatorio Astronomico di Roma, Via Frascati 33, I-00040 Monte Porzio Catone (Italy); Tritschler, A.; Reardon, K. P., E-mail: prom@oact.inaf.it [National Solar Observatory/Sacramento Peak, P.O. Box 62, Sunspot, NM 88349-0062 (United States)

2013-07-01T23:59:59.000Z

326

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

327

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

328

On fibrils and field lines: The nature of H$\\alpha$ fibrils in the solar chromosphere  

E-Print Network [OSTI]

Observations of the solar chromosphere in the line-core of the \\Halpha\\ line show dark elongated structures called fibrils that show swaying motion. We performed a 3D radiation-MHD simulation of a network region, and computed synthetic \\Halpha\\ images from this simulation to investigate the relation between fibrils and the magnetic field lines in the chromosphere. The periods, amplitudes and phase-speeds of the synthetic fibrils are consistent with those observed. We analyse the relation between the synthetic fibrils and the field lines threading through them, and find that some fibrils trace out the same field line along the fibril's length, but there are also fibrils that sample different field lines at different locations along their length. Fibrils sample the same field lines on a time scale of $\\sim200$~s. This is shorter than their own lifetime. We analysed the evolution of the atmosphere along a number of field lines that thread through fibrils and find that they carry slow-mode waves that load mass in...

Leenaarts, Jorrit; van der Voort, Luc Rouppe

2015-01-01T23:59:59.000Z

329

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

330

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

331

Nuclear Magnetic Resonance in Semiconductors. II. Quadrupole Broadening of Nuclear Magnetic Resonance Lines by Elastic Axial Deformation  

Science Journals Connector (OSTI)

Nuclear electric-quadrupole moments interact with electric-field gradients at the nucleus. In a perfect cubic crystal, the average gradients vanish and there are no quadrupolar interactions. Nuclear magnetic resonance studies of the semiconductors InSb and GaSb have revealed no quadrupolar interactions in our samples, indicating a high degree of crystalline perfection. By applying stresses to these crystals, we have been able to destroy the crystalline symmetry reversibly, thereby producing quadrupole broadening of the nuclear magnetic resonance lines. Strains of less than 10-4 have been detected and the resulting field gradients measured. The "gradient-elastic" proportionality constants connecting stress and field gradient are discussed in relation to crystal symmetry and have been deduced from the measurements.

R. G. Shulman; B. J. Wyluda; P. W. Anderson

1957-08-15T23:59:59.000Z

332

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

333

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

334

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

335

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...

336

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...

337

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

338

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

339

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

340

Baryon masses in the three-state Potts field theory in a weak magnetic field  

E-Print Network [OSTI]

The 3-state Potts field theory describes the scaling limit of the 3-state Potts model on the two-dimensional lattice near its continuous phase transition point. In the presence of thermal and magnetic field perturbations, the 3-state Potts field theory in the ordered phase exhibits confinement of kinks, which allows both mesons and baryons. We calculate the masses of light baryons in this model in the weak confinement regime in leading order of the small magnetic field. In leading order of perturbation theory, the light baryons can be viewed as bound states of three quantum particles - the kinks, which move on a line and interact via a linear potential. We determine the masses of the lightest baryons by numerical solution of the associated non-relativistic one-dimensional quantum three-body problem.

S. B. Rutkevich

2014-08-08T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic field lines" 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

Comparison Between Two Models for Interactions Between Electric and Magnetic Fields and Proteins in Cell Membranes  

E-Print Network [OSTI]

, Melbourne, Australia. Departments of 2 Medical Radiation Physics and 3 Neurosurgery, Lund University, Lund Lines; Interaction Models; Biological Effects Introduction Static magnetic and electric fields occur naturally; time-varying fields, however, do not. These man-made fields have health consequences remains

Halgamuge, Malka N.

342

Confinement of monopole field lines in a superconductor at T {ne} 0  

SciTech Connect (OSTI)

We apply the Bogoliubov-de Gennes equations to the confinement of a monopole-antimonopole pair in a superconductor. This is related to the problem of a quark-antiquark pair bound by a confining string, consisting of a colour-electric flux tube, dual to the magnetic vortex of type-II superconductors. We study the confinement of the field lines due to the superconducting state and calculate the effective potential between the two monopoles. The monopoles can be simulated in a real experiment inserting two long and thin magnetic rods. At short distances the potential is Coulombic and at large distances the potential is linear, as previously determined solving the Ginzburg-Landau equations. The magnetic field lines and the string tension are also studied as a function of the temperature T. Because we take into account the explicit fermionic degrees of freedom, this work may open new perspectives to the breaking of chiral symmetry or to colour superconductivity.

Cardoso, Marco [Departamento de Fisica, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Centro de Fisica Teorica de Particulas, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Centro de Fisica das Interaccoes Fundamentais, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Bicudo, Pedro [Departamento de Fisica, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Centro de Fisica Teorica de Particulas, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Sacramento, Pedro D. [Departamento de Fisica, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Centro de Fisica das Interaccoes Fundamentais, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)], E-mail: pdss@cfif.ist.utl.pt

2008-02-15T23:59:59.000Z

343

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.

344

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

345

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

346

Whole body MRI at 7 tesla using a 1H/19F elliptic body coil with whole-body, fat-signal insensitive, three dimensional magnetic field shim algorithm  

Science Journals Connector (OSTI)

...supercooling under magnetic field (2 kHz...human iPS cell lines from adult...human iPS cell lines for the supercooling under magnetic field group in 1...supercooling under magnetic field group (p0...human iPS cell lines which carry...

Leonard Liebes; Ray Lee; Songtao Liu; Michael Buckley; Howard Hochster; and Oded Gonen

2007-11-01T23:59:59.000Z

347

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

348

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

349

Electric and Magnetic Screening Masses at Finite Temperature from Generalized Polyakov-Line Correlations in Two-flavor Lattice QCD  

E-Print Network [OSTI]

Screenings of the quark-gluon plasma in electric and magnetic sectors are studied on the basis of generalized Polyakov-line correlation functions in lattice QCD simulations with two flavors of improved Wilson quarks. Using the Euclidean-time reflection ($\\R$) and the charge conjugation ($\\Ca$), electric and magnetic screening masses are extracted in a gauge invariant manner. Long distance behavior of the standard Polyakov-line correlation in the quark-gluon plasma is found to be dictated by the magnetic screening. Also, ratio of the two screening masses agrees with that obtained from the dimensionally-reduced effective field theory and the ${\\cal N}=4$ supersymmetric Yang-Mills theory.

Y. Maezawa; S. Aoki; S. Ejiri; T. Hatsuda; N. Ishii; K. Kanaya; N. Ukita; T. Umeda

2010-05-11T23:59:59.000Z

350

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

351

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

352

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

353

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

354

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

355

Polarization from aligned atoms as a diagnostics of circumstellar, AGN and interstellar magnetic fields: II. Atoms with Hyperfine Structure  

E-Print Network [OSTI]

We show that atomic alignment presents a reliable way to study topology of astrophysical magnetic fields. The effect of atomic alignment arises from modulation of the relative population of the sublevels of atomic ground state pumped by anisotropic radiation flux. As such aligned atoms precess in the external magnetic field and this affects the properties of the polarized radiation arising from both scattering and absorption by the atoms. As the result the polarizations of emission and absorption lines depend on the 3D geometry of the magnetic field as well as the direction and anisotropy of incident radiation. We consider a subset of astrophysically important atoms with hyperfine structure. For emission lines we obtain the dependencies of the direction of linear polarization on the directions of magnetic field and the incident pumping radiation. For absorption lines we establish when the polarization is perpendicular and parallel to magnetic field. For both emission and absorption lines we find the dependence on the degree of polarization on the 3D geometry of magnetic field. We claim that atomic alignment provides a unique tool to study magnetic fields in circumstellar regions, AGN, interplanetary and interstellar medium. This tool allows studying of 3D topology of magnetic fields and establish other important astrophysical parameters. We consider polarization arising from both atoms in the steady state and also as they undergo individual scattering of photons. We exemplify the utility of atomic alignment for studies of astrophysical magnetic fields by considering a case of Na alignment in a comet wake.

Huirong Yan; A. Lazarian

2006-11-09T23:59:59.000Z

356

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

357

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

358

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

359

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...

360

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

Note: This page contains sample records for the topic "magnetic field lines" 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

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

362

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

363

Effects of Magnet Errors in the ILC 14 mrad Extraction Line  

SciTech Connect (OSTI)

The ILC baseline extraction line is designed for 14 mrad horizontal crossing angle between e{sup +} and e{sup -} colliding beams at Interaction Point (IP). The extraction optics in the Interaction Region (IR) includes a detector integrated dipole field (anti-DID) to reduce orbit perturbation caused by the detector solenoid and minimize detector background. This paper presents a study of random field and alignment errors in the extraction magnets, compensation of the induced orbit perturbation, and effects of errors on extraction beam power loss. The results are obtained for the baseline ILC energy of 500 GeV center-of-mass and three options of beam parameters.

Toprek, Dragan; /VINCA Inst. Nucl. Sci., Belgrade; Nosochkov, Yuri; /SLAC

2009-05-08T23:59:59.000Z

364

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

365

DESIGN OF SUPERCONDUCTING COMBINED FUNCTION MAGNETS FOR THE 50 GEV PROTON BEAM LINE FOR THE J-PARC NEUTRINO EXPERIMENT.  

SciTech Connect (OSTI)

Superconducting combined function magnets will be utilized for the 50GeV-750kW proton beam line for the J-PARC neutrino experiment and an R and D program has been launched at KEK. The magnet is designed to provide a combined function with a dipole field of 2.59 T and a quadrupole field of 18.7 T/m in a coil aperture of 173.4 mm. A single layer coil is proposed to reduce the fabrication cost and the coil arrangement in the 2-D cross-section results in left-right asymmetry. This paper reports the design study of the magnet.

WANDERER,P.; ET AL.

2003-06-15T23:59:59.000Z

366

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

367

THE Ly{alpha} LINES OF H I AND He II: A DIFFERENTIAL HANLE EFFECT FOR EXPLORING THE MAGNETISM OF THE SOLAR TRANSITION REGION  

SciTech Connect (OSTI)

The Ly{alpha} line of He II at 304 Angstrom-Sign is one of the spectral lines of choice for EUV channels of narrowband imagers on board space telescopes, which provide spectacular intensity images of the outer solar atmosphere. Since the magnetic field information is encoded in the polarization of the spectral line radiation, it is important to investigate whether the He II line radiation from the solar disk can be polarized, along with its magnetic sensitivity. Here we report some theoretical predictions concerning the linear polarization signals produced by scattering processes in this strong emission line of the solar transition region, taking into account radiative transfer and the Hanle effect caused by the presence of organized and random magnetic fields. We find that the fractional polarization amplitudes are significant ({approx}1%), even when considering the wavelength-integrated signals. Interestingly, the scattering polarization of the Ly{alpha} line of He II starts to be sensitive to the Hanle effect for magnetic strengths B {approx}> 100 G (i.e., for magnetic strengths of the order of and larger than the Hanle saturation field of the hydrogen Ly{alpha} line at 1216 Angstrom-Sign ). We therefore propose simultaneous observations of the scattering polarization in both Ly{alpha} lines to facilitate magnetic field measurements in the upper solar chromosphere. Even the development of a narrowband imaging polarimeter for the He II 304 Angstrom-Sign line alone would be already of great diagnostic value for probing the solar transition region.

Trujillo Bueno, Javier; Stepan, Jiri; Belluzzi, Luca, E-mail: jtb@iac.es, E-mail: stepan@iac.es, E-mail: belluzzi@iac.es [Instituto de Astrofisica de Canarias, 38205 La Laguna, Tenerife (Spain)

2012-02-10T23:59:59.000Z

368

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

369

Magnetic fields during the early stages of massive star formation – I. Accretion and disc evolution  

Science Journals Connector (OSTI)

......due to the condition of ideal MHD. Note the different spatial...the gas. As we consider ideal MHD, the field lines cannot diffuse...Keplerian discs. Figure 8 Phase diagram of magnetic field and rotational...by several authors for ideal MHD simulations (Allen et al. 2003......

D. Seifried; R. Banerjee; R. S. Klessen; D. Duffin; R. E. Pudritz

2011-10-21T23:59:59.000Z

370

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

371

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

372

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

373

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

374

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

375

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

376

Tailoring of electron flow current in magnetically insulated transmission lines J. P. Martin,2,3  

E-Print Network [OSTI]

Tailoring of electron flow current in magnetically insulated transmission lines J. P. Martin,2,3 M of the drive pulse. It is clear that neither fixed gap nor constant-impedance transmission lines are optimal the impedance profiles developed in a radial disk magnetically insulated transmission line geometry. The input

377

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

378

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.

379

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

380

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

Note: This page contains sample records for the topic "magnetic field lines" 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

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

382

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

383

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

384

Barriers in the transition to global chaos in collisionless magnetic reconnection. I. Ridges of the finite time Lyapunov exponent field  

SciTech Connect (OSTI)

The transitional phase from local to global chaos in the magnetic field of a reconnecting current layer is investigated. Regions where the magnetic field is stochastic exist next to regions where the field is more regular. In regions between stochastic layers and between a stochastic layer and an island structure, the field of the finite time Lyapunov exponent (FTLE) shows a structure with ridges. These ridges, which are special gradient lines that are transverse to the direction of minimum curvature of this field, are approximate Lagrangian coherent structures (LCS) that act as barriers for the transport of field lines.

Borgogno, D. [Dipartimento di Energetica, Politecnico di Torino, Torino (Italy); Grasso, D. [Dipartimento di Energetica, Politecnico di Torino, Torino (Italy); CNR Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Dipartimento di Energetica, Politecnico di Torino, Torino (Italy); Pegoraro, F. [Physics Department, Pisa University, Pisa, CNISM (Italy); Schep, T. J. [Physics Department, Eindhoven University of Technology, Eindhoven (Netherlands)

2011-10-15T23:59:59.000Z

385

Light narrowing of magnetic resonance lines in dense, optically pumped alkali-metal vapor  

Science Journals Connector (OSTI)

A new and unusual phenomenon which we call light narrowing is reported and discussed in this paper. We discovered this effect in dense, spin-polarized cesium vapor optically pumped with a cw blue dye laser beam tuned to the second resonance D1 line (4593 Å). We observe a significant narrowing of the radio-frequency power-broadened magnetic resonance lines (linewidths narrow by as much as a factor of 2.5) when the intensity of the circularly polarized incident dye laser beam is increased by either focusing the beam or by the removal of attenuating filters from the focused beam. The magnetic resonance linewidths in spin-polarized cesium vapor were measured over a wide range of cesium number densities (5×1012 cm-3 ?[Cs]?1×1016 cm-3). This corresponds to cesium spinexchange rates of 4.5×103 to 9×106 sec-1. For low cesium number densities (5×1012 1×1015 cm-3) this light-narrowing effect almost completely disappears. In the limit of low-radio-frequency power the magnetic resonance linewidths for focused and unfocused dye laser beam are nearly the same. Experimental observations on this new effect are presented in detail. In the latter part of this paper a self-contained theoretical treatment of the light-narrowing effect is developed. Using Bloch equations in the presence of optical pumping, spin relaxation (diffusion, electron randomization), rapid spin exchange, and radio-frequency magnetic field, expressions for magnetic resonance line shapes are derived. In general, we find good agreement between our experimental results and the theory.

N. D. Bhaskar; J. Camparo; W. Happer; A. Sharma

1981-06-01T23:59:59.000Z

386

Four cavity efficiency enhanced magnetically insulated line oscillator  

DOE Patents [OSTI]

A four cavity, efficient magnetically insulated line oscillator (C4-E MILO) having seven vanes and six cavities formed within a tube-like structure surrounding a cathode is disclosed. The C4-E MILO has a primary slow wave structure which is comprised of four vanes and the four cavities located near a microwave exit end of the tube-like structure. The primary slow wave structure is the four cavity portion of the magnetically insulated line oscillator (MILO). An RF choke is provided which is comprised of three of the vanes and two of the cavities. The RF choke is located near a pulsed power source portion of the tube-like structure surrounding the cathode. The RF choke increases feedback in the primary slow wave structure, prevents microwaves generated in the primary slow wave structure from propagating towards the pulsed power source and modifies downstream electron current so as to enhance microwave power generation. A beam dump/extractor is located at the exit end of the oscillator tube for extracting microwave power from the oscillator, and in conjunction with an RF extractor vane, which comprises the fourth vane of the primary slow wave structure (nearest the exit) having a larger gap radius than the other vanes of the primary SWS, comprises an RF extractor. Uninsulated electron flow is returned downstream towards the exit along an anode/beam dump region located between the beam dump/extractor and the exit where the RF is radiated at said RF extractor vane located near the exit and the uninsulated electron flow is disposed at the beam dump/extractor. 34 figs.

Lemke, R.W.; Clark, M.C.; Calico, S.E.

1998-04-21T23:59:59.000Z

387

Four cavity efficiency enhanced magnetically insulated line oscillator  

DOE Patents [OSTI]

A four cavity, efficient magnetically insulated line oscillator (C4-E MILO) having seven vanes and six cavities formed within a tube-like structure surrounding a cathode. The C4-E MILO has a primary slow wave structure which is comprised of four vanes and the four cavities located near a microwave exit end of the tube-like structure. The primary slow wave structure is the four cavity (C4) portion of the magnetically insulated line oscillator (MILO). An RF choke is provided which is comprised of three of the vanes and two of the cavities. The RF choke is located near a pulsed power source portion of the tube-like structure surrounding the cathode. The RF choke increases feedback in the primary slow wave structure, prevents microwaves generated in the primary slow wave structure from propagating towards the pulsed power source and modifies downstream electron current so as to enhance microwave power generation. A beam dump/extractor is located at the exit end of the oscillator tube for extracting microwave power from the oscillator, and in conjunction with an RF extractor vane, which comprises the fourth vane of the primary slow wave structure (nearest the exit) having a larger gap radius than the other vanes of the primary SWS, comprises an RF extractor. Uninsulated electron flow is returned downstream towards the exit along an anode/beam dump region located between the beam dump/extractor and the exit where the RF is radiated at said RF extractor vane located near the exit and the uninsulated electron flow is disposed at the beam dump/extractor.

Lemke, Raymond W. (Albuquerque, NM); Clark, Miles C. (Albuquerque, NM); Calico, Steve E. (Albuquerque, NM)

1998-04-21T23:59:59.000Z

388

Profiled spectral lines generated in the field of Kerr superspinars  

SciTech Connect (OSTI)

String Theory suggests existence of primordial Kerr superspinars, extremely compact objects with external spacetime described by the Kerr naked singularity geometry. The primordial Kerr superspinars have to be converted to a near-extreme black hole due to accretion, but they could survive to the era of highly redshifted quasars. We study the shape of the profiled spectral lines generated by radiating rings or the innermost parts of Keplerian discs orbiting the Kerr superspinars. Influence of the superspinar surface location on the profiled lines is also considered. We demonstrate strong difference of the character of the profiled lines generated by radiating rings for all values of the superspinar spin and all values of the inclination angles of the observer when compared to those generated in the field of Kerr black holes. For small and mediate inclination angles there are large quantitative differences in the extension and position of the lines. For large inclination angles even strong qualitative difference appears as the profiled lines have a clear doubled character. The smaller, redshifted region of the profiled line is related to the photons reaching the regions near the superspinar surface. Strong differences are obtained also for profiled lines generated by the innermost parts of Keplerian discs especially in the shape of the line. The influence of the superspinar surface location is reflected in the intermediate parts of the the profiled lines. The line profiles can give a clear signature of the presence of a Kerr superspinar and in principle enable estimates of its surface location since the signatures of the superspinar surface location are of different character as those corresponding to the presence of the black hole horizon.

Schee, Jan; Stuchlík, Zdenek, E-mail: jan.schee@fpf.slu.cz, E-mail: zdenek.stuchlik@fpf.slu.cz [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava, Bezru?ovo nám. 13, Opava (Czech Republic)

2013-04-01T23:59:59.000Z

389

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...

390

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...

391

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...

392

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

393

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

394

Field lines twisting in a noisy corona: implications for energy storage and release, and initiation of solar eruptions  

E-Print Network [OSTI]

We present simulations modeling closed regions of the solar corona threaded by a strong magnetic field where localized photospheric vortical motions twist the coronal field lines. The linear and nonlinear dynamics are investigated in the reduced magnetohydrodynamic regime in Cartesian geometry. Initially the magnetic field lines get twisted and the system becomes unstable to the internal kink mode, confirming and extending previous results. As typical in this kind of investigations, where initial conditions implement smooth fields and flux-tubes, we have neglected fluctuations and the fields are laminar until the instability sets in. But previous investigations indicate that fluctuations, excited by photospheric motions and coronal dynamics, are naturally present at all scales in the coronal fields. Thus, in order to understand the effect of a photospheric vortex on a more realistic corona, we continue the simulations after kink instability sets in, when turbulent fluctuations have already developed in the co...

Rappazzo, A F; Einaudi, G

2013-01-01T23:59:59.000Z

395

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

396

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

397

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...

398

Determination of Topology Skeleton of Magnetic Fields in a Solar Active Region  

E-Print Network [OSTI]

The knowledge of magnetic topology is the key to understand magnetic energy release in astrophysics. Based on observed vector magnetograms, we have determined threedimensional (3D) topology skeleton of the magnetic fields in active region NOAA 10720. The skeleton consists of six 3D magnetic nulls and a network of corresponding spines, fans, and null-null lines. For the first time, we have identified a spiral magnetic null in Sun's corona. The magnetic lines of force twisted around the spine of the null, forming a 'magnetic wreath' with excess of free magnetic energy and resembling observed brightening structures at extraultraviolet (EUV) wavebands. We found clear evidence of topology eruptions which are referred to as the catastrophic changes of topology skeleton associated with a coronal mass ejection (CME) and an explosive X-ray flare. These results shed new lights in exploring the structural complexity and its role in explosive magnetic activity. In solar astrophysics and space science, the concept of flux rope has been widely used in modelling explosive magnetic activity, although their observational identity is obscure or, at least, lacking of necessary details. The current work suggests that the magnetic wreath associated with the 3D spiral null is likely an important class of the physical entity of flux ropes.

Hui Zhao; Jing-Xiu Wang; Jun Zhang; Chi-Jie Xiao; Hai-Min Wang

2007-12-20T23:59:59.000Z

399

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

400

TURBULENT AMPLIFICATION OF A MAGNETIC FIELD DRIVEN BY THE DYNAMO EFFECT AT RIPPLED SHOCKS  

SciTech Connect (OSTI)

We analytically derive the vorticity generated downstream of a two-dimensional (2D) rippled hydromagnetic shock neglecting fluid viscosity and resistivity. The growth of the turbulent component of the downstream magnetic field is driven by the motion of vortical eddies. We determine an analytic time evolution of the magnetic field amplification at shocks, so far described only numerically, until saturation occurs due to seed-field reaction to the whirling of field lines. The explicit expression of the amplification growth rate and of the nonlinear field back-reaction in terms of the parameters of shock and interstellar density fluctuation is derived from MHD jump conditions at rippled shocks. A magnetic field saturation up to the order of milli-Gauss and a short-term variability in the X-ray observations of supernova remnants can be obtained by using reasonable parameters for the interstellar turbulence.

Fraschetti, F. [Associated Member of LUTh, Observatoire de Paris, CNRS-UMR8102 and Universite Paris VII, 5 Place Jules Janssen, F-92195 Meudon Cedex, France. (France)

2013-06-20T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic field lines" 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

Exposure to transmission line electric fields during farming operations  

SciTech Connect (OSTI)

This paper describes an analysis of exposure to transmission line electric fields during typical farming operations. This analysis makes use of experimentally determined ''activity factors'' and time budget information for typical farms as compiled by the U.S. Department of Agriculture. A detailed exposure assessment for 18 ''typical farms'' (as defined by USDA) is provided for a base case 345 kV design. Exposure estimates for transmission lines ranging from 115-765 kV are provided for a representative farm.

Silva, M.; Huber, D.

1985-09-01T23:59:59.000Z

402

Optimization code with weighting function for the reconstruction of coronal magnetic fields  

E-Print Network [OSTI]

We developed a code for the reconstruction of nonlinear force-free and non-force-free coronal magnetic fields. The 3D magnetic field is computed numerically with the help of an optimization principle. The force-free and non-force-free codes are compiled in one program. The force-free approach needs photospheric vector magnetograms as input. The non-force-free code additionally requires the line-of-sight integrated coronal density distribution in combination with a tomographic inversion code. Previously the optimization approach has been used to compute magnetic fields using all six boundaries of a computational box. Here we extend this method and show how the coronal magnetic field can be reconstructed only from the bottom boundary, where the boundary conditions are measured with vector magnetographs. The program is planed for use within the Stereo mission.

T. Wiegelmann

2008-02-01T23:59:59.000Z

403

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

404

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...

405

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

406

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,...

407

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...

408

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...

409

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

410

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

411

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

412

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

413

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.

414

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

415

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

416

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

417

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

418

Extending the Concept of Separatrices to QSLs for Magnetic Reconnection  

E-Print Network [OSTI]

by the transport of magnetic field lines across separatrices, the set of field lines where the field-line linkage in field-line linkage, generalize the definition of separatrices. Magnetic reconnection is expected the magnetic field line linkage is discontinuous (Fig. 1). A particularly important location for reconnection

Demoulin, Pascal

419

Magnetic fields in the early universe in the string approach to MHD  

Science Journals Connector (OSTI)

There is a reformulation of magnetohydrodynamics in which the fundamental dynamical quantities are the positions and velocities of the lines of magnetic flux in the plasma, which turn out to obey equations of motion very much like ideal strings. We use this approach to study the evolution of a primordial magnetic field generated during the radiation-dominated era in the early universe. Causality dictates that the field lines form a tangled random network, and the string-like equations of motion, plus the assumption of perfect reconnection, inevitably lead to a self-similar solution for the magnetic field power spectrum. We present the predicted form of the power spectrum, and discuss insights gained from the string approximation, in particular the implications for the existence or nonexistence of an inverse cascade.

Mattias Christensson and Mark Hindmarsh

1999-08-13T23:59:59.000Z

420

Revised density of magnetized nuclear matter at the neutron drip line  

E-Print Network [OSTI]

We study the onset of neutron drip in high density matter in the presence of magnetic field. It has been found that for systems having only protons and electrons, in the presence of magnetic field >~ 10^{15}G, the neutronization occurs at a density which is atleast an order of magnitude higher compared to that in a nonmagnetic system. In a system with heavier ions, the effect of magnetic field, however, starts arising at a much higher field, >~ 10^{17}G. These results may have important implications in high magnetic neutron stars and white dwarfs and, in general, nuclear astrophysics when the system is embedded with high magnetic field.

M. V. Vishal; Banibrata Mukhopadhyay

2014-03-04T23:59:59.000Z

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


421

Formation of magnetic islands due to field perturbations in toroidal stellarators  

SciTech Connect (OSTI)

An explicit formulation is developed to determine the width of a magnetic island separatrix generated by magnetic field perturbations in a general toroidal stellarator geometry. A conventional method is employed to recast the analysis in a magnetic flux coordinate system without using any simplifying approximations. The island width is seen to be proportional to the square root of the Fourier harmonic of B{sup {rho}}/B{sup {zeta}} that is in resonance with the rational value of the rotational transform, where B{sup {rho}} and B{sup {zeta}} are contravariant normal and toroidal components of the perturbed magnetic field, respectively. The procedure, which is based on a representation of three-dimensional flux surfaces by double Fourier series, allows rapid and fairly accurate calculation of the island widths in real vacuum field configurations, without the need to follow field lines through numerical integration of the field line equations. Numerical results of the island width obtained in the flux coordinate representation for the Advanced Toroidal Facility agree closely with those determined from Poincare puncture points obtained by following field lines. 22 refs., 1 fig., 1 tab.

Lee, Deok Kyo.

1990-01-01T23:59:59.000Z

422

Gas insulated transmission line with insulators having field controlling recesses  

DOE Patents [OSTI]

A gas insulated transmission line having a novel insulator for supporting an inner conductor concentrically within an outer sheath. The insulator has a recess contiguous with the periphery of one of the outer and inner conductors. The recess is disposed to a depth equal to an optimum gap for the dielectric insulating fluid used for the high voltage insulation or alternately disposed to a large depth so as to reduce the field at the critical conductor/insulator interface.

Cookson, Alan H. (Pittsburgh, PA); Pederson, Bjorn O. (Chelmsford, MA)

1984-01-01T23:59:59.000Z

423

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

424

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

425

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.

426

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.

427

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.

428

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.

429

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

430

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

431

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

432

Electrical Conductivity of Dense Quark Matter with Fluctuations and Magnetic Field Included  

E-Print Network [OSTI]

We investigate the electrical conductivity(EC) of dense quark matter in the vicinity of the phase transition line. We show that: (i) At high density the Drude EC does not depend on the magnetic field up to $eB \\sim 10^{19} \\ G$. (ii) In the precritical region the fluctuation EC (paraconductivity) dominates over the Drude one.

B. O. Kerbikov; M. A. Andreichikov

2014-10-13T23:59:59.000Z

433

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

434

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:...

435

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...

436

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...

437

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

438

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

439

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

440

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

Note: This page contains sample records for the topic "magnetic field lines" 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

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

442

Interstellar Hydroxyl Masers in the Galaxy. II. Zeeman Pairs and the Galactic Magnetic Field  

E-Print Network [OSTI]

We have identified and classified Zeeman pairs in the survey by Argon, Reid, & Menten of massive star-forming regions with 18 cm (2 Pi 3/2, J = 3/2) OH maser emission. We have found a total of more than 100 Zeeman pairs in more than 50 massive star-forming regions. The magnetic field deduced from the Zeeman splitting has allowed us to assign an overall line-of-sight magnetic field direction to many of the massive star-forming regions. Combining these data with other data sets obtained from OH Zeeman splitting, we have looked for correlations of magnetic field directions between star-forming regions scattered throughout the Galaxy. Our data do not support a uniform, Galactic-scale field direction, nor do we find any strong evidence of magnetic field correlations within spiral arms. However, our data suggest that in the Solar neighborhood the magnetic field outside the Solar circle is oriented clockwise as viewed from the North Galactic Pole, while inside the Solar circle it is oriented counterclockwise. This pattern, including the magnetic field reversal near the Sun, is in agreement with results obtained from pulsar rotation measures.

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

2003-07-08T23:59:59.000Z

443

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

444

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

445

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

446

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

447

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

448

Field Lines Twisting in a Noisy Corona: Implications for Energy Storage and Release, and Initiation of Solar Eruptions  

Science Journals Connector (OSTI)

We present simulations modeling closed regions of the solar corona threaded by a strong magnetic field where localized photospheric vortical motions twist the coronal field lines. The linear and nonlinear dynamics are investigated in the reduced magnetohydrodynamic regime in Cartesian geometry. Initially the magnetic field lines get twisted and the system becomes unstable to the internal kink mode, confirming and extending previous results. As typical in this kind of investigations, where initial conditions implement smooth fields and flux-tubes, we have neglected fluctuations and the fields are laminar until the instability sets in. However, previous investigations indicate that fluctuations, excited by photospheric motions and coronal dynamics, are naturally present at all scales in the coronal fields. Thus, in order to understand the effect of a photospheric vortex on a more realistic corona, we continue the simulations after kink instability sets in, when turbulent fluctuations have already developed in the corona. In the nonlinear stage the system never returns to the simple initial state with ordered twisted field lines, and kink instability does not occur again. Nevertheless, field lines get twisted, although in a disordered way, and energy accumulates at large scales through an inverse cascade. This energy can subsequently be released in micro-flares or larger flares, when interaction with neighboring structures occurs or via other mechanisms. The impact on coronal dynamics and coronal mass ejections initiation is discussed.

A. F. Rappazzo; M. Velli; G. Einaudi

2013-01-01T23:59:59.000Z

449

FIELD LINES TWISTING IN A NOISY CORONA: IMPLICATIONS FOR ENERGY STORAGE AND RELEASE, AND INITIATION OF SOLAR ERUPTIONS  

SciTech Connect (OSTI)

We present simulations modeling closed regions of the solar corona threaded by a strong magnetic field where localized photospheric vortical motions twist the coronal field lines. The linear and nonlinear dynamics are investigated in the reduced magnetohydrodynamic regime in Cartesian geometry. Initially the magnetic field lines get twisted and the system becomes unstable to the internal kink mode, confirming and extending previous results. As typical in this kind of investigations, where initial conditions implement smooth fields and flux-tubes, we have neglected fluctuations and the fields are laminar until the instability sets in. However, previous investigations indicate that fluctuations, excited by photospheric motions and coronal dynamics, are naturally present at all scales in the coronal fields. Thus, in order to understand the effect of a photospheric vortex on a more realistic corona, we continue the simulations after kink instability sets in, when turbulent fluctuations have already developed in the corona. In the nonlinear stage the system never returns to the simple initial state with ordered twisted field lines, and kink instability does not occur again. Nevertheless, field lines get twisted, although in a disordered way, and energy accumulates at large scales through an inverse cascade. This energy can subsequently be released in micro-flares or larger flares, when interaction with neighboring structures occurs or via other mechanisms. The impact on coronal dynamics and coronal mass ejections initiation is discussed.

Rappazzo, A. F. [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, DE 19716 (United States); Velli, M. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Einaudi, G., E-mail: rappazzo@udel.edu [Berkeley Research Associates, Inc., 6537 Mid Cities Avenue, Beltsville, MD 20705 (United States)

2013-07-10T23:59:59.000Z

450

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

451

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

452

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

453

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

454

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

455

Magnetic reconnection | Princeton Plasma Physics Lab  

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

"reconnection") refers to the breaking and reconnecting of oppositely directed magnetic field lines in a plasma. In the process, magnetic field energy is converted to plasma...

456

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

457

Multifrequency Polarimetry of the Nrao 140 Jet: Possible Detection of a Helical Magnetic Field and Constraints on its Pitch Angle  

E-Print Network [OSTI]

We present results from multifrequency polarimetry of NRAO 140 using the Very Long Baseline Array. These observations allow us to reveal the distributions of both the polarization position angle and the Faraday rotation measure (RM). These distributions are powerful tools to discern the projected and line-of-sight components of the magnetic field, respectively. We find a systematic gradient in the RM distribution, with its sign being opposite at either side of the jet with respect to the jet axis. The sign of the RM changes only with the direction of the magnetic field component along the line of sight, so this can be explained by the existence of helical magnetic components associated with the jet itself. We derive two constraints for the pitch angle of the helical magnetic field from the distributions of the RM and the projected magnetic field; the RM distribution indicates that the helical fields are tightly wound, while that of the projected magnetic field suggests they are loosely wound around the jet axis. This inconsistency may be explained if the Faraday rotator is not cospatial with theemitting region. Our results may point toward a physical picture in which an ultra-relativistic jet (spine) with a loosely wound helical magnetic field is surrounded by a sub-relativistic wind layer (sheath) with a tightly wound helical magnetic field.

Keiichi Asada; Makoto Inoue; Masanori Nakamura; Seiji Kameno; Hiroshi Nagai

2008-06-26T23:59:59.000Z

458

VECTOR TOMOGRAPHY FOR THE CORONAL MAGNETIC FIELD. II. HANLE EFFECT MEASUREMENTS  

SciTech Connect (OSTI)

In this paper, we investigate the feasibility of saturated coronal Hanle effect vector tomography or the application of vector tomographic inversion techniques to reconstruct the three-dimensional magnetic field configuration of the solar corona using linear polarization measurements of coronal emission lines. We applied Hanle effect vector tomographic inversion to artificial data produced from analytical coronal magnetic field models with equatorial and meridional currents and global coronal magnetic field models constructed by extrapolation of real photospheric magnetic field measurements. We tested tomographic inversion with only Stokes Q, U, electron density, and temperature inputs to simulate observations over large limb distances where the Stokes I parameters are difficult to obtain with ground-based coronagraphs. We synthesized the coronal linear polarization maps by inputting realistic noise appropriate for ground-based observations over a period of two weeks into the inversion algorithm. We found that our Hanle effect vector tomographic inversion can partially recover the coronal field with a poloidal field configuration, but that it is insensitive to a corona with a toroidal field. This result demonstrates that Hanle effect vector tomography is an effective tool for studying the solar corona and that it is complementary to Zeeman effect vector tomography for the reconstruction of the coronal magnetic field.

Kramar, M. [Physics Department, The Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064 (United States); Inhester, B. [Max-Planck-Institut fuer Sonnensystemforschung, Max-Plank-Str. 2, D-37191 Katlenburg-Lindau (Germany); Lin, H. [Institute for Astronomy, University of Hawaii at Manoa, 34 Ohia Ku Street, Pukalani, Maui, HI 96768 (United States); Davila, J., E-mail: maxim.i.kramar@nasa.gov, E-mail: Joseph.M.Davila@nasa.gov, E-mail: inhester@mps.mpg.de, E-mail: lin@ifa.hawaii.edu [NASA-GSFC, Code 671, Greenbelt, MD 20771 (United States)

2013-09-20T23:59:59.000Z

459

Theory of optical properties of II-VI semiconductor quantum dots containing a single magnetic ion in a strong magnetic field  

Science Journals Connector (OSTI)

We present a microscopic theory of the magnetic field dependence of the optical properties of II–VI semiconductor quantum dots containing a single magnetic (Mn) impurity. The single-particle electron and heavy-hole states are described exactly by two-dimensional harmonic oscillators in a magnetic field, the Mn ion is treated as a spin of an isoelectronic impurity, and the quantum dot anisotropy is included perturbatively. The electron-hole direct, short-, and long-range exchange electron-hole Coulomb interactions, as well as the short-range spin-spin contact exchange interaction of the electron and the hole with the magnetic impurity is included. The electron-hole-Mn states are expanded in a finite number of configurations controlled by the number of confined electronic quantum dot shells and the full interacting Hamiltonian is diagonalized numerically in this basis. The absorption and emission spectrum is predicted as a function of photon energy, magnetic field, number of confined shells, and anisotropy. It is shown that the magnetic-field-induced enhancement of the exchange interaction of the Mn spin with the exciton is largely canceled by increased electron-hole Coulomb interactions. The predicted weak magnetic field dependence of the spacing of emission lines agrees well with the results of the spin model at low magnetic fields but differs at higher magnetic fields. Correlations in the exciton-Mn complex are predicted to determine absorption spectra.

Anna H. Trojnar; Marek Korkusi?ski; Marek Potemski; Pawel Hawrylak

2012-04-06T23:59:59.000Z

460

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

Note: This page contains sample records for the topic "magnetic field lines" 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

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

462

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...

463

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...

464

An Energy-Stabilized Varied-Line-Space-Monochromator UndulatorBeam Line for PEEM Illumination and Magnetic Circular Dichroism  

SciTech Connect (OSTI)

A new undulator beam line has been built and commissioned at the Advanced Light Source for illumination of the PEEM3 microscope. The beam line delivers high flux beams over an energy range from C1s through the transition metals to include the M edges of the magnetic rare earth elements. We present details of the optical design, and data on the performance of the zero-order tracking of the photon energy.

Warwick, Tony; McKinney, Wayne; Domning, Ed; Doran, Andrew; Padmore, Howard

2006-06-01T23:59:59.000Z

465

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

466

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

467

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.

468

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

469

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...

470

Electro Acceleration in a Geomagnetic Field Line Resonance  

SciTech Connect (OSTI)

A hybrid MHD kinetic electron model in dipolar coordinates is used to sim- ulate the upward current region of a geomagnetic Field Line Resonance (FLR) system for a realistic ambient electron temperatures of a keV. It is found that mirror force e ects result in potential drops su#14;cient to accelerate electrons to energies in excess of a keV in support of eld aligned currents on the or- der of 0.5 #22;µA/m2. The wave energy dissipated in this acceleration would com- pletely damp an undriven FLR with an equatorial width of 0.5 RE within two resonance cycles.

Peter Damiano and J.R. Johnson

2012-08-17T23:59:59.000Z

471

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

472

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

473

Tail-ion transport and Knudsen layer formation in the presence of magnetic fields  

SciTech Connect (OSTI)

Knudsen layer losses of tail fuel ions could reduce significantly the fusion reactivity of highly compressed cylindrical and spherical targets in inertial confinement fusion (ICF). With the class of magnetized ICF targets in mind, the effect of embedded magnetic fields on Knudsen layer formation is investigated for the first time. The modified energy scaling of ion diffusivity in magnetized hot spots is found to suppress the preferential losses of tail-ions perpendicular to the magnetic field lines to a degree that the tail distribution can be at least partially, if not fully, restored. Two simple threshold conditions are identified leading to the restoration of fusion reactivity in magnetized hot spots. A kinetic equation for tail-ion transport in the presence of a magnetic field is derived, and solutions to the equation are obtained numerically in simulations. Numerical results confirm the validity of the threshold conditions for restored reactivity and identify two different asymptotic regimes of the fusion fuel. While Knudsen layer formation is shown to be suppressed entirely in strongly magnetized cylindrical hot spot cavities, uniformly magnetized spherical cavities demonstrate remnant, albeit reduced, levels of tail-ion depletion.

Schmit, P. F. [Sandia National Laboratories, MS 1186, P.O. Box 5800, Albuquerque, New Mexico 87185-1186 (United States)] [Sandia National Laboratories, MS 1186, P.O. Box 5800, Albuquerque, New Mexico 87185-1186 (United States); Molvig, Kim; Nakhleh, C. W. [Los Alamos National Laboratory, MS B259, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, MS B259, P.O. Box 1663, Los Alamos, New Mexico 87545 (United States)

2013-11-15T23:59:59.000Z

474

Exoplanet-Induced Chromospheric Activity: Realistic Light Curves from Solar-type Magnetic Fields  

E-Print Network [OSTI]

There is growing observational evidence for some kind of interaction between stars and close-in extrasolar giant planets. Shkolnik et al. reported variability in the chromospheric Ca H and K lines of HD 179949 and upsilon And that seemed to be phased with the planet's orbital period, instead of the stellar rotational period. However, the observations also indicate that the chromospheric light curves do not repeat exactly, which may be expected for a planet plowing through a variable stellar magnetic field. Using the complex solar magnetic field (modeled with the Potential Field Source Surface technique) as a guide, we simulate the shapes of light curves that would arise from planet-star interactions that are channeled along magnetic field lines. We also study the orbit-to-orbit variability of these light curves and how they vary from solar minimum (i.e., a more or less axisymmetric stretched dipole) to solar maximum (a superposition of many higher multipole moments) fields. Considering more complex magnetic fields introduces new difficulties in the interpretation of observations, but it may also lead to valuable new diagnostics of exoplanet magnetospheres.

Steven R. Cranmer; Steven H. Saar

2007-02-20T23:59:59.000Z

475

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

476

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

477

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

478

Measurements of the Fermilab 200 MeV transfer line quadrupole magnets  

SciTech Connect (OSTI)

This report presents the results of measurements of two quadrupole magnets that are used in the 200 MeV transfer line. The measurements were performed to obtain data to evaluate the suitability of these magnets for use in a 400 MeV transfer line once the Linac Upgrade is complete. In order to provide a basis for comparison, data were obtained from Fermilab's Magnet Test Facility of measurements of magnets of similar size and strength that were built for the Loma Linda project. These Loma Linda magnets are possible replacements for the ones presently in the 200 MeV transfer line. The Fermilab Linac Upgrade includes the reconfiguration of the transfer line that runs from the linac to the booster in order to handle the higher beam energy. Nominally, the quadrupole strengths will need to be 1.5 times their current operating points. This report will use a value of 1.7 to allow a tuning range to account differences in geometry between the old and new lines. Another goal in the design of the new transfer line is to produce a non-steering line. A complaint about the current line is that steering results from any attempt to re-tune the line. 18 figs., 3 tabs.

Kroc, T.