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1

Strongest non-destructive magnetic field: world record set at 100-tesla level  

E-Print Network [OSTI]

- 1 - Strongest non-destructive magnetic field: world record set at 100-tesla level March 22, 2012), the scientists achieved a whopping 100.75 tesla--a magnetic field nearly 100 times more powerful than a junkyard and insulators. The 100-tesla level is roughly equivalent to 2 million times Earth's magnetic field. #12;- 2

2

Landau levels of scalar QED in time-dependent magnetic fields  

SciTech Connect (OSTI)

The Landau levels of scalar QED undergo continuous transitions under a homogeneous, time-dependent magnetic field. We analytically formulate the Klein–Gordon equation for a charged spinless scalar as a Cauchy initial value problem in the two-component first order formalism and then put forth a measure that classifies the quantum motions into the adiabatic change, the nonadiabatic change, and the sudden change. We find the exact quantum motion and calculate the pair-production rate when the magnetic field suddenly changes as a step function. -- Highlights: •We study the Landau levels of scalar QED in time-dependent magnetic fields. •Instantaneous Landau levels make continuous transitions but keep parity. •The Klein–Gordon equation is expressed in the two-component first order formalism. •A measure is advanced that characterizes the quantum motions into three categories. •A suddenly changing magnetic field produces pairs of charged scalars from vacuum.

Kim, Sang Pyo, E-mail: sangkim@kunsan.ac.kr

2014-05-15T23:59:59.000Z

3

Energy Levels and Wave Functions of Vector Bosons in Homogeneous Magnetic Field  

E-Print Network [OSTI]

We aimed to obtain the energy levels of spin-1 particles moving in a constant magnetic field. The method used here is completely algebraic. In the process to obtain the energy levels the wave function is choosen in terms of Laguerre Polynomials.

K. Sogut; A. Havare; I. Acikgoz

2001-10-24T23:59:59.000Z

4

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

5

Effects on chickens of continuous exposure to low level electromagnetic, electric, and magnetic fields  

E-Print Network [OSTI]

for the degree of MASTER OF SCIENCE December 1972 Major Subjects Nuclear Engineering (Health Physics) EFFECTS ON CHI CKENS OF CONT INUOUS EXPOSURE TO LOW LEVEL ELECTRONAGNETIC, ELECTRIC, AND MAGNETIC 1 IELDS A Thesis by ROBERT SHERWOOD HOWELL Approved... exposure to ionizing radiation. The treated groups appear to have a significantly reduced growth rate and a slightly increased feed conversion ratio. The spleen weight in the 260 MHz {calculated average input power density of 0. 029 mW/cm ) group...

Howell, Robert Sherwood

1972-01-01T23:59:59.000Z

6

Level crossings and zero-field splitting in the {Cr8}-cubane spin-cluster studied using inelastic neutron scattering and magnetization  

SciTech Connect (OSTI)

Inelastic neutron scattering (INS) in variable magnetic field and high-field magnetization measurements in the millikelvin temperature range were performed to gain insight into the low-energy magnetic excitation spectrum and the field-induced level crossings in the molecular spin cluster {Cr8}-cubane. These complementary techniques provide consistent estimates of the lowest level-crossing field. The overall features of the experimental data are explained using an isotropic Heisenberg model, based on three distinct exchange interactions linking the eight CrIII paramagnetic centers (spins s = 3/2), that is supplemented with a relatively large molecular magnetic anisotropy term for the lowest S = 1 multiplet. It is noted that the existence of the anisotropy is clearly evident from the magnetic field dependence of the excitations in the INS measurements, while the magnetization measurements are not sensitive to its effects.

Vaknin, D. [Ames Laboratory; Garlea, Vasile O [ORNL; Demmel, F. [ISIS Facility, Rutherford Appleton Laboratory; Mamontov, Eugene [ORNL; Nojiri, H [Institute for Materials Research, Tohoku University, Sendai, Japan; Martin, Catalin [Florida State University; Chiorescu, Irinel [Florida State University; Qiu, Y. [National Institute of Standards and Technology (NIST); Luban, M. [Ames Laboratory; Kogerler, P. [Ames Laboratory; Fielden, J. [Ames Laboratory; Engelhardt, L [Francis Marion University, Florence, South Sarolina; Rainey, C [Francis Marion University, Florence, South Sarolina

2010-01-01T23:59:59.000Z

7

Magnetic Field Measurement System  

SciTech Connect (OSTI)

A magnetic field measurement system was designed, built and installed at MAX Lab, Sweden for the purpose of characterizing the magnetic field produced by Insertion Devices (see Figure 1). The measurement system consists of a large granite beam roughly 2 feet square and 14 feet long that has been polished beyond laboratory grade for flatness and straightness. The granite precision coupled with the design of the carriage yielded minimum position deviations as measured at the probe tip. The Hall probe data collection and compensation technique allows exceptional resolution and range while taking data on the fly to programmable sample spacing. Additional flip coil provides field integral data.

Kulesza, Joe; Johnson, Eric; Lyndaker, Aaron; Deyhim, Alex; Waterman, Dave; Blomqvist, K. Ingvar [Advanced Design Consulting USA, 126 Ridge Road, P.O. Box 187, Lansing, NY 14882 (United States); Dunn, Jonathan Hunter [MAX-lab, SE-221 00 Lund (Sweden)

2007-01-19T23:59:59.000Z

8

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

9

Fast superconducting magnetic field switch  

DOE Patents [OSTI]

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

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

1996-01-01T23:59:59.000Z

10

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

11

Matching field effects at tesla-level magnetic fields in critical current density in high-Tc superconductors containing self-assembled columnar defects  

SciTech Connect (OSTI)

We have investigated the superconductive transport properties of YBa2Cu3O7 films containing self-assembled columnar arrays of second phase SrZrO3 or BaSnO3 precipitates. A matching condition between columnar pinning sites (aligned at or near the c axis) and external magnetic flux, tilted with respect to them, is identified in the critical current JC.H/ data. The results for the material containing SrZrO3-based pins are analyzed within a simple intuitive model. At matching, the critical current is enhanced above the model prediction. In complementary contact-free investigations of BaSnO3-doped material, matching effects are observed over a wide range of temperatures in the field dependence of JC.H/. The deduced matching fields agree reasonably well with the densities of columnar pins directly observed by scanning electron microscopy.

Sinclair, J. [University of Tennessee, Knoxville (UTK); Zuev, Yuri L [ORNL; Cantoni, Claudia [ORNL; Wee, Sung Hun [ORNL; Varanasi, C. V. [University of Dayton Research Institute; Thompson, James R [ORNL; Christen, David K [ORNL

2012-01-01T23:59:59.000Z

12

Discovery of magnetic fields in hot subdwarfs  

E-Print Network [OSTI]

We present polarisation measurements of sdB and sdO stars using FORS1 on the VLT. The observations were made as part of a project to determine whether magnetic fields in two super-metal-rich stars can explain their extreme abundance peculiarities. Field strengths of up to ~1.5 kG have been measured at varying levels of significance in each of our six targets, however no clear evidence was found between apparently normal subdwarfs and the metal-rich objects. The origin of the magnetic fields is unknown. We also discuss the implications of our measurements for magnetic flux conservation in late stages of stellar evolution.

S. J. O'Toole; S. Jordan; S. Friedrich; U. Heber

2005-03-10T23:59:59.000Z

13

Measurements of magnetic field alignment  

SciTech Connect (OSTI)

The procedure for installing Superconducting Super Collider (SSC) dipoles in their respective cryostats involves aligning the average direction of their field with the vertical to an accuracy of 0.5 mrad. The equipment developed for carrying on these measurements is described and the measurements performed on the first few prototypes SSC magnets are presented. The field angle as a function of position in these 16.6 m long magnets is a characteristic of the individual magnet with possible feedback information to its manufacturing procedure. A comparison of this vertical alignment characteristic with a magnetic field intensity (by NMR) characteristic for one of the prototypes is also presented. 5 refs., 7 figs.

Kuchnir, M.; Schmidt, E.E.

1987-11-06T23:59:59.000Z

14

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

15

Are Cluster Magnetic Fields Primordial ?  

E-Print Network [OSTI]

We present results of a detailed and fully non-linear numerical and analytical investigation of magnetic field evolution from the very earliest cosmic epochs to the present. We find that, under reasonable assumptions concerning the efficiency of a putative magnetogenesis era during cosmic phase transitions, surprisingly strong magnetic fields 10^{-13} - 10^{-11} Gauss, on comparatively small scales 100 pc - 10 kpc may survive to the present. Building on prior work on the evolution of magnetic fields during the course of gravitational collapse of a cluster, which indicates that pre-collapse fields of 4\\times 10^{-12} Gauss extant on small scales may suffice to produce clusters with acceptable Faraday rotation measures, we question the widely hold view that cluster magnetic fields may not be entirely of primordial origin.

Robi Banerjee; Karsten Jedamzik

2004-09-07T23:59:59.000Z

16

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...

17

Hyperon bulk viscosity in strong magnetic fields  

E-Print Network [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 non-leptonic weak process involving $\\Lambda$ hyperons and direct Urca processes are calculated here. In the presence of a strong magnetic field of $10^{17}$ 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.

Monika Sinha; Debades Bandyopadhyay

2009-06-06T23:59:59.000Z

18

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

19

Magnetic field measurements on the sun and implications for stellar magnetic field observations  

SciTech Connect (OSTI)

Results of solar magnetic field measurements in plages, sunspot umbrae, and sunspot penumbrae using high spectral resolution, unpolarized infrared H band spectral data are presented. A Fourier deconvolution analysis scheme similar to that utilized for stellar magnetic field measurements is adopted. As an example, a field strength of 3240 + or - 450 G is determined in a sunspot umbra combined with a value of 2000 + or - 180 G in the associated penumbra. These values are compared with a direct measurement of the spot umbra and penumbra field strengths based on the observed separation of the Zeeman components of the magnetically sensitive lines. Possible origins for the discrepancy between the results inferred by these two different techniques are discussed. The Fourier analysis results confirm the widespread occurrence of kilogauss level fields in the solar photosphere. The implications of the solar results for stellar magnetic field measurements are considered. 45 references.

Sun, W.H.; Giampapa, M.S.; Worden, S.P.

1987-01-01T23:59:59.000Z

20

Thermalization in External Magnetic Field  

E-Print Network [OSTI]

In the AdS/CFT framework meson thermalization in the presence of a constant external magnetic field in a strongly coupled gauge theory has been studied. In the gravitational description the thermalization of mesons corresponds to the horizon formation on the flavour D7-brane which is embedded in the AdS_5 x S^5 background in the probe limit. The apparent horizon forms due to the time-dependent change in the baryon number chemical potential, the injection of baryons in the gauge theory. We will numerically show that the thermalization happens even faster in the presence of the magnetic field on the probe brane. We observe that this reduction in the thermalization time sustains up to a specific value of the magnetic field.

Ali-Akbari, Mohammad

2012-01-01T23:59:59.000Z

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

The origin, evolution and signatures of primordial magnetic fields  

E-Print Network [OSTI]

The universe is magnetized on all scales probed so far. On the largest scales, galaxies and galaxy clusters host magnetic fields at the micro Gauss level coherent on scales up to ten kpc. Recent observational evidence suggests that even the intergalactic medium in voids could host a weak $\\sim 10^{-16}$ Gauss magnetic field, coherent on Mpc scales. An intriguing possibility is that these observed magnetic fields are a relic from the early universe, albeit one which has been subsequently amplified and maintained by a dynamo in collapsed objects. We review here the origin, evolution and signatures of primordial magnetic fields. After a brief summary of magnetohydrodynamics in the expanding universe, we turn to magnetic field generation during inflation and other phase transitions. We trace the linear and nonlinear evolution of the generated primordial fields through the radiation era, including viscous effects. Sensitive observational signatures of primordial magnetic fields on the cosmic microwave background, ...

Subramanian, Kandaswamy

2015-01-01T23:59:59.000Z

22

HIGH-FIELD SUPERCONDUCTING ACCELERATOR MAGNETS  

E-Print Network [OSTI]

D. C. 'Niobium-Titanium Superconducting Material s ', in S.14, 1982 HIGH-FIELD SUPERCONDUCTING ACCELERATOR MAGNETS C.SUMAG-68 HIGH-FIELD SUPERCONDUCTING ACCELERATOR MAGNETS* C.

Taylor, C.

2011-01-01T23:59:59.000Z

23

Turbulence and Magnetic Fields in Clouds  

E-Print Network [OSTI]

We discuss several categories of models which may explain the IMF, including the possible role of turbulence and magnetic fields.

Shantanu Basu

2004-11-15T23:59:59.000Z

24

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

25

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

26

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

27

National High Magnetic Field Laboratory  

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

ANNUAL REPORT RESEARCH HIGHLIGHTS: CONDENSED MATTER SCIENCE Technique development, graphene, magnetism & magnetic materials, topological insulators, quantum fl uids & solids,...

28

Magnetic fluid flow phenomena in DC and rotating magnetic fields  

E-Print Network [OSTI]

An investigation of magnetic fluid experiments and analysis is presented in three parts: a study of magnetic field induced torques in magnetorheological fluids, a characterization and quantitative measurement of properties ...

Rhodes, Scott E. (Scott Edward), 1981-

2004-01-01T23:59:59.000Z

29

Baryon onset in a magnetic field  

E-Print Network [OSTI]

The critical baryon chemical potential for the onset of nuclear matter is a function of the vacuum mass and the binding energy. Both quantities are affected by an external magnetic field. We show within two relativistic mean-field models - including magnetic catalysis, but omitting the anomalous magnetic moment - that a magnetic field increases both the vacuum mass and the binding energy. For sufficiently large magnetic fields, the effect on the vacuum mass dominates and as a result the critical baryon chemical potential is increased.

Alexander Haber; Florian Preis; Andreas Schmitt

2014-12-19T23:59:59.000Z

30

Discovery of magnetic fields in CPNs  

E-Print Network [OSTI]

For the first time we have directly detected magnetic fields in central stars of planetary nebulae by means of spectro-polarimetry with FORS1 at the VLT. In all four objects of our sample we found kilogauss magnetic fields, in NGC 1360 and LSS1362 with very high significance, while in Abell36 and EGB5 the existence of a magnetic field is probable but with less certainty. This discovery supports the hypothesis that the non-spherical symmetry of most planetary nebulae is caused by magnetic fields in AGB stars. Our high discovery rate demands mechanisms to prevent full conservation of magnetic flux during the transition to white dwarfs.

S. Jordan; K. Werner; S. J. O'Toole

2004-10-21T23:59:59.000Z

31

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

32

Magnetic field topology of accreting white dwarfs  

E-Print Network [OSTI]

We report first results of our systematic investigation of the magnetic field structure of rotating single magnetic white dwarfs and of white dwarfs in magnetic cataclysmic variables. The global magnetic field distributions on the isolated white dwarf HE1045-0908 and the accreting white dwarfs in EF Eri and CP Tuc have been derived from phase-resolved flux and polarization spectra obtained with FORS1 at the ESO VLT using the systematic method of Zeeman tomography.

Klaus Reinsch; Fabian Euchner; Klaus Beuermann; Stefan Jordan

2003-02-04T23:59:59.000Z

33

DC-based magnetic field controller  

DOE Patents [OSTI]

A magnetic field controller for laboratory devices and in particular to dc operated magnetic field controllers for mass spectrometers, comprising a dc power supply in combination with improvements to a hall probe subsystem, display subsystem, preamplifier, field control subsystem, and an output stage.

Kotter, Dale K. (Shelley, ID); Rankin, Richard A. (Ammon, ID); Morgan, John P,. (Idaho Falls, ID)

1994-01-01T23:59:59.000Z

34

DC-based magnetic field controller  

DOE Patents [OSTI]

A magnetic field controller is described for laboratory devices and in particular to dc operated magnetic field controllers for mass spectrometers, comprising a dc power supply in combination with improvements to a Hall probe subsystem, display subsystem, preamplifier, field control subsystem, and an output stage. 1 fig.

Kotter, D.K.; Rankin, R.A.; Morgan, J.P.

1994-05-31T23:59:59.000Z

35

Constraining primordial magnetic fields with future cosmic shear surveys  

SciTech Connect (OSTI)

The origin of astrophysical magnetic fields observed in galaxies and clusters of galaxies is still unclear. One possibility is that primordial magnetic fields generated in the early Universe provide seeds that grow through compression and turbulence during structure formation. A cosmological magnetic field present prior to recombination would produce substantial matter clustering at intermediate/small scales, on top of the standard inflationary power spectrum. In this work we study the effect of this alteration on one particular cosmological observable, cosmic shear. We adopt the semi-analytic halo model in order to describe the non-linear clustering of matter, and feed it with the altered mass variance induced by primordial magnetic fields. We find that the convergence power spectrum is, as expected, substantially enhanced at intermediate/small angular scales, with the exact amplitude of the enhancement depending on the magnitude and power-law index of the magnetic field power spectrum. Specifically, for a fixed amplitude, the effect of magnetic fields is larger for larger spectral indices. We use the predicted statistical errors for a future wide-field cosmic shear survey, on the model of the ESA Cosmic Vision mission Euclid, in order to forecast constraints on the amplitude of primordial magnetic fields as a function of the spectral index. We find that the amplitude will be constrained at the level of ? 0.1 nG for n{sub B} ? ?3, and at the level of ? 10{sup ?7} nG for n{sub B} ? 3. The latter is at the same level of lower bounds coming from the secondary emission of gamma-ray sources, implying that for high spectral indices Euclid will certainly be able to detect primordial magnetic fields, if they exist. The present study shows how large-scale structure surveys can be used for both understanding the origins of astrophysical magnetic fields and shedding new light on the physics of the pre-recombination Universe.

Fedeli, C. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Moscardini, L., E-mail: cosimo.fedeli@astro.ufl.edu, E-mail: lauro.moscardini@unibo.it [Dipartimento di Astronomia, Università di Bologna, Via Ranzani 1, 40127 Bologna (Italy)

2012-11-01T23:59:59.000Z

36

Magnetic fields in anisotropic relativistic stars  

E-Print Network [OSTI]

Relativistic, spherically symmetric configurations consisting of a gravitating magnetized anisotropic fluid are studied. For such configurations, we obtain static equilibrium solutions with an axisymmetric, poloidal magnetic field produced by toroidal electric currents. The presence of such a field results in small deviations of the shape of the configuration from spherical symmetry. This in turn leads to the modification of an equation for the current and correspondingly to changes in the structure of the internal magnetic field for the systems supported by the anisotropic fluid, in contrast to the case of an isotropic fluid, where such deviations do not affect the magnetic field.

Vladimir Folomeev; Vladimir Dzhunushaliev

2015-02-28T23:59:59.000Z

37

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

2013-03-20T23:59:59.000Z

38

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

39

Relativistic generation of vortex and magnetic field  

SciTech Connect (OSTI)

The implications of the recently demonstrated relativistic mechanism for generating generalized vorticity in purely ideal dynamics [Mahajan and Yoshida, Phys. Rev. Lett. 105, 095005 (2010)] are worked out. The said mechanism has its origin in the space-time distortion caused by the demands of special relativity; these distortions break the topological constraint (conservation of generalized helicity) forbidding the emergence of magnetic field (a generalized vorticity) in an ideal nonrelativistic dynamics. After delineating the steps in the ''evolution'' of vortex dynamics, as the physical system goes from a nonrelativistic to a relativistically fast and hot plasma, a simple theory is developed to disentangle the two distinct components comprising the generalized vorticity--the magnetic field and the thermal-kinetic vorticity. The ''strength'' of the new universal mechanism is, then, estimated for a few representative cases; in particular, the level of seed fields, created in the cosmic setting of the early hot universe filled with relativistic particle-antiparticle pairs (up to the end of the electron-positron era), are computed. Possible applications of the mechanism in intense laser produced plasmas are also explored. It is suggested that highly relativistic laser plasma could provide a laboratory for testing the essence of the relativistic drive.

Mahajan, S. M. [Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States); Yoshida, Z. [Graduate School of Frontier Sciences, University of Tokyo, Chiba 277-8561 (Japan)

2011-05-15T23:59:59.000Z

40

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

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

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

42

Electronic properties of graphite in tilted magnetic fields  

SciTech Connect (OSTI)

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

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

2014-05-15T23:59:59.000Z

43

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

44

Magnetic monopole field exposed by electrons  

E-Print Network [OSTI]

Magnetic monopoles have provided a rich field of study, leading to a wide area of research in particle physics, solid state physics, ultra-cold gases, superconductors, cosmology, and gauge theory. So far, no true magnetic monopoles were found experimentally. Using the Aharonov-Bohm effect, one of the central results of quantum physics, shows however, that an effective monopole field can be produced. Understanding the effects of such a monopole field on its surroundings is crucial to its observation and provides a better grasp of fundamental physical theory. We realize the diffraction of fast electrons at a magnetic monopole field generated by a nanoscopic magnetized ferromagnetic needle. Previous studies have been limited to theoretical semiclassical optical calculations of the motion of electrons in such a monopole field. Solid state systems like the recently studied 'spin ice' provide a constrained system to study similar fields, but make it impossible to separate the monopole from the material. Free space ...

Béché, A; Van Tendeloo, G; Verbeeck, J

2013-01-01T23:59:59.000Z

45

Colour superconductivity in a strong magnetic field  

E-Print Network [OSTI]

We explore the effects of an applied strong external magnetic field in a three flavour massless colour superconductor. The long-range component of the B field that penetrates the superconductor enhances some quark condensates, leading to a different condensation pattern. The external field also reduces the flavour symmetries in the system, and thus it changes drastically the corresponding low energy physics. Our considerations are relevant for the study of highly magnetized compact stars.

Efrain J. Ferrer; Vivian de la Incera; Cristina Manuel

2005-11-30T23:59:59.000Z

46

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

47

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

48

HIGH-FIELD SUPERCONDUCTING ACCELERATOR MAGNETS  

E-Print Network [OSTI]

D. C. 'Niobium-Titanium Superconducting Material s ', in S.Nb -Ti and Nb3Sn superconductors. , •• ,""" s. S. Clamp, Tie14, 1982 HIGH-FIELD SUPERCONDUCTING ACCELERATOR MAGNETS C.

Taylor, C.

2011-01-01T23:59:59.000Z

49

Lunar magnetic field measurements with a cubesat  

E-Print Network [OSTI]

We have developed a mission concept that uses 3-unit cubesats to perform new measurements of lunar magnetic fields, less than 100 meters above the Moon’s surface. The mission calls for sending the cubesats on impact ...

Garrick-Bethell, Ian

50

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

51

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

52

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

53

Magnetic nanoparticles for applications in oscillating magnetic field  

SciTech Connect (OSTI)

Enzymatic and thermochemical catalysis are both important industrial processes. However, the thermal requirements for each process often render them mutually exclusive: thermochemical catalysis requires high temperature that denatures enzymes. One of the long-term goals of this project is to design a thermocatalytic system that could be used with enzymatic systems in situ to catalyze reaction sequences in one pot; this system would be useful for numerous applications e.g. conversion of biomass to biofuel and other commodity products. The desired thermocatalytic system would need to supply enough thermal energy to catalyze thermochemical reactions, while keeping the enzymes from high temperature denaturation. Magnetic nanoparticles are known to generate heat in an oscillating magnetic field through mechanisms including hysteresis and relaxational losses. We envisioned using these magnetic nanoparticles as the local heat source embedded in sub-micron size mesoporous support to spatially separate the particles from the enzymes. In this study, we set out to find the magnetic materials and instrumental conditions that are sufficient for this purpose. Magnetite was chosen as the first model magnetic material in this study because of its high magnetization values, synthetic control over particle size, shape, functionalization and proven biocompatibility. Our experimental designs were guided by a series of theoretical calculations, which provided clues to the effects of particle size, size distribution, magnetic field, frequency and reaction medium. Materials of theoretically optimal size were synthesized, functionalized, and their effects in the oscillating magnetic field were subsequently investigated. Under our conditions, the materials that clustered e.g. silica-coated and PNIPAM-coated iron oxides exhibited the highest heat generation, while iron oxides embedded in MSNs and mesoporous iron oxides exhibited the least bulk heating. It is worth noting that the specific loss power of PNIPAM-coated Fe{sub 3}O{sub 4} was peculiarly high, and the heat loss mechanism of this material remains to be elucidated. Since thermocatalysis is a long-term goal of this project, we also investigated the effects of the oscillating magnetic field system for the synthesis of 7-hydroxycoumarin-3-carboxylic acid. Application of an oscillating magnetic field in the presence of magnetic particles with high thermal response was found to effectively increase the reaction rate of the uncatalyzed synthesis of the coumarin derivative compared to the room temperature control.

Peeraphatdit, Chorthip

2010-12-15T23:59:59.000Z

54

Plasma heating in a variable magnetic field  

SciTech Connect (OSTI)

The problem of particle acceleration in a periodically variable magnetic field that either takes a zero value or passes through zero is considered. It is shown that, each time the field [0]passes through zero, the particle energy increases abruptly. This process can be regarded as heating in the course of which plasma particles acquire significant energy within one field period. This mechanism of plasma heating takes place in the absence of collisions between plasma particles and is analogous to the mechanism of magnetic pumping in collisional plasma considered by Alfven.

Kichigin, G. N., E-mail: king@iszf.irk.ru [Russian Academy of Sciences, Institute of Solar-Terrestrial Physics (Russian Federation)

2013-05-15T23:59:59.000Z

55

Discovery of magnetic fields in hot subdwarfs  

E-Print Network [OSTI]

We present initial results of a project to measure mean longitudinal magnetic fields in a group of sdB/OB/O stars. The project was inspired by the discovery of three super-metal-rich sdOB stars, each having metals (e.g. Ti, V) enhanced by factors of 10^3 to 10^5. Similar behaviour is observed in chemically peculiar A stars, where strong magnetic fields are responsible for the enrichment. With this in mind, we obtained circularly polarised spectra of two of the super-metal-rich sdOBs, two "normal" sdBs and two sdOs using FORS1 on the ESO/VLT. By examining circular polarisation in the hydrogen Balmer lines and in helium lines, we have detected magnetic fields with strengths of 1-2 kG in most of our targets. This suggests that such fields are relatively common in hot subdwarfs.

S. J. O'Toole; S. Jordan; S. Friedrich; U. Heber

2004-10-02T23:59:59.000Z

56

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

SciTech Connect (OSTI)

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

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

2013-09-01T23:59:59.000Z

57

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

58

MAGNETIC FIELDS FROM QCD PHASE TRANSITIONS  

SciTech Connect (OSTI)

We study the evolution of QCD phase transition-generated magnetic fields (MFs) in freely decaying MHD turbulence of the expanding universe. We consider an MF generation model that starts from basic non-perturbative QCD theory and predicts stochastic MFs with an amplitude of the order of 0.02 {mu}G and small magnetic helicity. We employ direct numerical simulations to model the MHD turbulence decay and identify two different regimes: a 'weakly helical' turbulence regime, when magnetic helicity increases during decay, and 'fully helical' turbulence, when maximal magnetic helicity is reached and an inverse cascade develops. The results of our analysis show that in the most optimistic scenario the magnetic correlation length in the comoving frame can reach 10 kpc with the amplitude of the effective MF being 0.007 nG. We demonstrate that the considered model of magnetogenesis can provide the seed MF for galaxies and clusters.

Tevzadze, Alexander G. [Faculty of Exact and Natural Sciences, Javakhishvili Tbilisi State University, 1 Chavchavadze Avenue, Tbilisi 0128 (Georgia); Kisslinger, Leonard; Kahniashvili, Tina [McWilliams Center for Cosmology and Department of Physics, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Brandenburg, Axel, E-mail: aleko@tevza.org [Nordita, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, SE-10691 Stockholm (Sweden)

2012-11-01T23:59:59.000Z

59

Holographic non-Fermi liquid in a background magnetic field  

SciTech Connect (OSTI)

We study the effects of a nonzero magnetic field on a class of 2+1 dimensional non-Fermi liquids, recently found in [Hong Liu, John McGreevy, and David Vegh, arXiv:0903.2477.] by considering properties of a Fermionic probe in an extremal AdS{sup 4} black hole background. Introducing a similar fermionic probe in a dyonic AdS{sup 4} black hole geometry, we find that the effect of a magnetic field could be incorporated in a rescaling of the probe fermion's charge. From this simple fact, we observe interesting effects like gradual disappearance of the Fermi surface and quasiparticle peaks at large magnetic fields and changes in other properties of the system. We also find Landau level like structures and oscillatory phenomena similar to the de-Haas-van Alphen effect.

Basu, Pallab; He Jianyang; Mukherjee, Anindya; Shieh, Hsien-Hang [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, B.C. V6T 1Z1 (Canada)

2010-08-15T23:59:59.000Z

60

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

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

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

62

Magnetic fields and density functional theory  

SciTech Connect (OSTI)

A major focus of this dissertation is the development of functionals for the magnetic susceptibility and the chemical shielding within the context of magnetic field density functional theory (BDFT). These functionals depend on the electron density in the absence of the field, which is unlike any other treatment of these responses. There have been several advances made within this theory. The first of which is the development of local density functionals for chemical shieldings and magnetic susceptibilities. There are the first such functionals ever proposed. These parameters have been studied by constructing functionals for the current density and then using the Biot-Savart equations to obtain the responses. In order to examine the advantages and disadvantages of the local functionals, they were tested numerically on some small molecules.

Salsbury Jr., Freddie

1999-02-01T23:59:59.000Z

63

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

64

Magnetic fields of the W4 superbubble  

E-Print Network [OSTI]

Superbubbles and supershells are the channels for transferring mass and energy from the Galactic disk to the halo. Magnetic fields are believed to play a vital role in their evolution. We study the radio continuum and polarized emission properties of the W4 superbubble to determine its magnetic field strength. New sensitive radio continuum observations were made at 6 cm, 11 cm, and 21 cm. The total intensity measurements were used to derive the radio spectrum of the W4 superbubble. The linear polarization data were analysed to determine the magnetic field properties within the bubble shells. The observations show a multi-shell structure of the W4 superbubble. A flat radio continuum spectrum that stems from optically thin thermal emission is derived from 1.4 GHz to 4.8 GHz. By fitting a passive Faraday screen model and considering the filling factor fne , we obtain the thermal electron density ne = 1.0/\\sqrt{fne} (\\pm5%) cm^-3 and the strength of the line-of-sight component of the magnetic field B// = -5.0/\\sq...

Gao, X Y; Reich, P; Han, J L; Kothes, R

2015-01-01T23:59:59.000Z

65

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

66

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

67

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

68

Magnetic Fields in Molecular Cloud Cores  

E-Print Network [OSTI]

Observations of magnetic field strengths imply that molecular cloud fragments are individually close to being in a magnetically critical state, even though both magnetic field and column density measurements range over two orders of magnitude. The turbulent pressure also approximately balances the self-gravitational pressure. These results together mean that the one-dimensional velocity dispersion $\\sigv$ is proportional to the mean \\Alf speed of a cloud $\\va$. Global models of MHD turbulence in a molecular cloud show that this correlation is naturally satisfied for a range of different driving strengths of the turbulence. For example, an increase of turbulent driving causes a cloud expansion which also increases $\\va$. Clouds are in a time averaged balance but exhibit large oscillatory motions, particularly in their outer rarefied regions. We also discuss models of gravitational fragmentation in a sheet-like region in which turbulence has already dissipated, including the effects of magnetic fields and ion-neutral friction. Clouds with near-critical mass-to-flux ratios lead to subsonic infall within cores, consistent with some recent observations of motions in starless cores. Conversely, significantly supercritical clouds are expected to produce extended supersonic infall.

Shantanu Basu

2004-10-22T23:59:59.000Z

69

Primordial magnetic field amplification from turbulent reheating  

SciTech Connect (OSTI)

We analyze the possibility of primordial magnetic field amplification by a stochastic large scale kinematic dynamo during reheating. We consider a charged scalar field minimally coupled to gravity. During inflation this field is assumed to be in its vacuum state. At the transition to reheating the state of the field changes to a many particle/anti-particle state. We characterize that state as a fluid flow of zero mean velocity but with a stochastic velocity field. We compute the scale-dependent Reynolds number Re(k), and the characteristic times for decay of turbulence, t{sub d} and pair annihilation t{sub a}, finding t{sub a} << t{sub d}. We calculate the rms value of the kinetic helicity of the flow over a scale L and show that it does not vanish. We use this result to estimate the amplification factor of a seed field from the stochastic kinematic dynamo equations. Although this effect is weak, it shows that the evolution of the cosmic magnetic field from reheating to galaxy formation may well be more complex than as dictated by simple flux freezing.

Calzetta, Esteban [Departamento de Física, FCEyN-UBA and IFIBA-CONICET, Cdad. Universitaria, Buenos Aires (Argentina); Kandus, Alejandra, E-mail: calzetta@df.uba.ar, E-mail: kandus@uesc.br [LATO - DCET - UESC. Rodovia Ilhéus-Itabuna, km 16 s/n, CEP: 45662-900, Salobrinho, Ilhéus-BA (Brazil)

2010-08-01T23:59:59.000Z

70

Magnetic Fields in Population III Star Formation  

SciTech Connect (OSTI)

We study the buildup of magnetic fields during the formation of Population III star-forming regions, by conducting cosmological simulations from realistic initial conditions and varying the Jeans resolution. To investigate this in detail, we start simulations from identical initial conditions, mandating 16, 32 and 64 zones per Jeans length, and studied the variation in their magnetic field amplification. We find that, while compression results in some amplification, turbulent velocity fluctuations driven by the collapse can further amplify an initially weak seed field via dynamo action, provided there is sufficient numerical resolution to capture vortical motions (we find this requirement to be 64 zones per Jeans length, slightly larger than, but consistent with previous work run with more idealized collapse scenarios). We explore saturation of amplification of the magnetic field, which could potentially become dynamically important in subsequent, fully-resolved calculations. We have also identified a relatively surprising phenomena that is purely hydrodynamic: the higher-resolved simulations possess substantially different characteristics, including higher infall-velocity, increased temperatures inside 1000 AU, and decreased molecular hydrogen content in the innermost region. Furthermore, we find that disk formation is suppressed in higher-resolution calculations, at least at the times that we can follow the calculation. We discuss the effect this may have on the buildup of disks over the accretion history of the first clump to form as well as the potential for gravitational instabilities to develop and induce fragmentation.

Turk, Matthew J.; Oishi, Jeffrey S.; Abel, Tom; Bryan, Greg

2012-02-22T23:59:59.000Z

71

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

72

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

73

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 China c National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive

Garmestani, Hamid

74

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

75

Homogenous BSCCO-2212 Round Wires for Very High Field Magnets  

SciTech Connect (OSTI)

The performance demands on modern particle accelerators generate a relentless push towards higher field magnets. In turn, advanced high field magnet development places increased demands on superconducting materials. Nb3Sn conductors have been used to achieve 16 T in a prototype dipole magnet and are thought to have the capability for {approx}18 T for accelerator magnets (primarily dipoles but also higher order multipole magnets). However there have been suggestions and proposals for such magnets higher than 20 T. The High Energy Physics Community (HEP) has identified important new physics opportunities that are enabled by extremely high field magnets: 20 to 50 T solenoids for muon cooling in a muon collider (impact: understanding of neutrinos and dark matter); and 20+ T dipoles and quadrupoles for high energy hadron colliders (impact: discovery reach far beyond present). This proposal addresses the latest SBIR solicitation that calls for grant applications that seek to develop new or improved superconducting wire technologies for magnets that operate at a minimum of 12 Tesla (T) field, with increases up to 15 to 20 T sought in the near future (three to five years). The long-term development of accelerator magnets with fields greater than 20 T will require superconducting wires having significantly better high-field properties than those possessed by current Nb{sub 3}Sn or other A15 based wires. Given the existing materials science base for Bi-2212 wire processing, we believe that Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (Bi-2212) round wires can be produced in km-long piece lengths with properties suitable to meet both the near term and long term needs of the HEP community. The key advance will be the translation of this materials science base into a robust, high-yield wire technology. While the processing and application of A15 materials have advanced to a much higher level than those of the copper oxide-based, high T{sub c} (HTS) counterparts, the HTS materials have the very significant advantage of an extremely high H{sub c2}. For this reason, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (Bi-2212, or 2212) in the form of a multifilamentary Ag alloy matrix composite is beginning to attract the interest of the magnet community for future extremely high-field magnets or magnet-insert coils for 4.2K operation. Fig. 1 shows an example of excellent JE (engineering current density) in Bi-2212 round wire at fields up to 45 T, demonstrating the potential for high field applications of this material. For comparison, the Nb{sub 3}Sn wires used in magnets in the 16-18 T range typically perform with J{sub E} in the range 200-500 A/mm{sup 2}; the Bi-2212 wire retains this level of performance to fields at least as high as 45 T, and probably significantly higher. Bi-2212 conductors have in fact been used to generate a 25 T field in a superconducting insert magnet. These two factors- the very high field critical current performance of Bi-2212, and the already demonstrated capability of this material for high field magnets up to 25 T, strongly suggest this material as a leading contender for the next generation high field superconducting (HFS) wire. This potential was recognized by the US Academy of Science's Committee on Opportunities in High Magnetic Field Science. Their report of the same name specifically calls out the high field potential for this material, and suggests that 30 T magnets appear feasible based on the performance of 2212. There are several requirements for HFS conductors. The most obvious is J{sub E} (B, T), the engineering current density at the field and temperature of operation. As shown in Fig. 1, Bi-2212 excels in this regard. Stability requirements for magnets dictate that the effective filament diameter should be less than 30 micrometers, something that Bi-2212 multifilamentary wire can uniquely satisfy among the HFS superconducting wire technologies. Additional requirements include mechanical properties that prevent stress limitation of J{sub E} at the operating conditions, resistive transition index (n-value) suffic

Dr. Scott Campbell

2012-06-30T23:59:59.000Z

76

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

77

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

78

Localized Magnetic Fields in Arbitrary Directions Using Patterned Nanomagnets  

E-Print Network [OSTI]

with the option of applying electric fields, for example, to move a quantum dot between regions where the magnetic magnetic films have a long history, for example, in bubble memory,6 but on scales required for spintronic electric fields, for example, to move a quantum dot between regions where the magnetic-field direction

Dunin-Borkowski, Rafal E.

79

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

80

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

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

Fluorescent lamp with static magnetic field generating means  

DOE Patents [OSTI]

A fluorescent lamp wherein magnetic field generating means (e.g., permanent magnets) are utilized to generate a static magnetic field across the respective electrode structures of the lamp such that maximum field strength is located at the electrode's filament. An increase in efficacy during operation has been observed. 2 figs.

Moskowitz, P.E.; Maya, J.

1987-09-08T23:59:59.000Z

82

Closed-field capacitive liquid level sensor  

DOE Patents [OSTI]

A liquid level sensor based on a closed field circuit comprises a ring oscillator using a symmetrical array of plate units that creates a displacement current. The displacement current varies as a function of the proximity of a liquid to the plate units. The ring oscillator circuit produces an output signal with a frequency inversely proportional to the presence of a liquid. A continuous liquid level sensing device and a two point sensing device are both proposed sensing arrangements. A second set of plates may be located inside of the probe housing relative to the sensing plate units. The second set of plates prevent any interference between the sensing plate units.

Kronberg, J.W.

1995-01-01T23:59:59.000Z

83

On the control of solidification using magnetic fields and magnetic field Baskar Ganapathysubramanian and Nicholas Zabaras1  

E-Print Network [OSTI]

On the control of solidification using magnetic fields and magnetic field gradients Baskar and Aerospace Engineering, 188 Frank H.T. Rhodes Hall, Cornell University, Ithaca, NY 14853-3801, USA Abstract solidified material can be suitably affected. Most of the magnetic field approaches to melt flow control rely

Zabaras, Nicholas J.

84

Magnetic Helicity Generation from the Cosmic Axion Field  

E-Print Network [OSTI]

The coupling between a primordial magnetic field and the cosmic axion field generates a helical component of the magnetic field around the time in which the axion starts to oscillate. If the energy density of the seed magnetic field is comparable to the energy density of the universe at that time, then the resulting magnetic helicity is about |H_B| \\simeq (10^{-20} G)^2 kpc and remains constant after its generation. As a corollary, we find that the standard properties of the oscillating axion remain unchanged even in the presence of very strong magnetic fields.

L. Campanelli; M. Giannotti

2005-12-12T23:59:59.000Z

85

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

86

Flavoured Large N Gauge Theory on a Compact Space with an External Magnetic Field  

E-Print Network [OSTI]

The phase structure of flavoured N=2 SYM on a three sphere in an external magnetic field is studied. The pairing effect of the magnetic field competes with the dissociating effect of the Casimir free energy, leading to an interesting phase structure of confined and deconfined phases separated by a critical curve of a first order quantum phase transition. At vanishing magnetic field the phase transition is of a third order. For sufficiently strong magnetic field, the only stable phase is the confined phase and magnetic catalysis of chiral symmetry breaking is realized. The meson spectra of the theory exhibit Zeeman splitting and level crossing and feature a finite jump at the phase transition between the confined and deconfined phases. At strong magnetic field the ground state has a massless mode corresponding to the Goldstone boson associated with the spontaneously broken U(1) R-symmetry analogous to the eta' meson in QCD.

Veselin G. Filev; Matthias Ihl

2014-06-22T23:59:59.000Z

87

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

88

Temperature measurement of axisymmetric flames under the influence of magnetic field using Talbot interferometry  

SciTech Connect (OSTI)

Combustion process control is related with ecological improvement and the problem of energy efficiency; hence it has a wide interest at both economical and scientific levels. Application of a magnetic field is one of the most promising methods of combustion control. The presence of magnetic field induces the changes in flame behavior. The effect of uniform magnetic field developed by permanent magnet is studied by Talbot interferometry using circular gratings. Experimental results show a small decrease in flame temperature and increase in flame dimensions.

Agarwal, Shilpi, E-mail: sipi.agarwal@gmail.com, E-mail: manojklakra@gmail.com, E-mail: cshakher@iddc.iitd.ac.in; Kumar, Manoj, E-mail: sipi.agarwal@gmail.com, E-mail: manojklakra@gmail.com, E-mail: cshakher@iddc.iitd.ac.in; Shakher, Chandra, E-mail: sipi.agarwal@gmail.com, E-mail: manojklakra@gmail.com, E-mail: cshakher@iddc.iitd.ac.in [Instrument Design Development Centre, Indian Institute of Technology Delhi, HauzKhas, New Delhi - 110016 (India)

2014-10-15T23:59:59.000Z

89

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.

90

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

91

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

92

Magnetic Fields in Quasar Cores II  

E-Print Network [OSTI]

Multi-frequency polarimetry with the Very Long Baseline Array (VLBA) telescope has revealed absolute Faraday Rotation Measures (RMs) in excess of 1000 rad/m/m in the central regions of 7 out of 8 strong quasars studied (e.g., 3C 273, 3C 279, 3C 395). Beyond a projected distance of ~20 pc, however, the jets are found to have |RM| < 100 rad/m/m. Such sharp RM gradients cannot be produced by cluster or galactic-scale magnetic fields, but rather must be the result of magnetic fields organized over the central 1-100 pc. The RMs of the sources studied to date and the polarization properties of BL Lacs, quasars and galaxies are shown to be consistent so far with the predictions of unified schemes. The direct detection of high RMs in these quasar cores can explain the low fractional core polarizations usually observed in quasars at centimeter wavelengths as the result of irregularities in the Faraday screen on scales smaller than the telescope beam. Variability in the RM of the core is reported for 3C 279 between observations taken 1.5 years apart, indicating that the Faraday screen changes on that timescale, or that the projected superluminal motion of the inner jet components samples a new location in the screen with time. Either way, these changes in the Faraday screen may explain the dramatic variability in core polarization properties displayed by quasars.

G. B. Taylor

1999-11-22T23:59:59.000Z

93

alternating magnetic fields: Topics by E-print Network  

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

We argue that the lower limit on the void magnetic field can be recovered, if a small fraction of the magnetic energy contained in the void galaxies or void bordering AGNs is...

94

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

95

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

96

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

97

Magnetic Propulsion of Intense Lithium Streams in a Tokamak Magnetic Field  

E-Print Network [OSTI]

Magnetic Propulsion of Intense Lithium Streams in a Tokamak Magnetic Field Leonid E. Zakharov the theory of magnetic propulsion of liquid lithium streams and their stability in tokamaks and other interactions with the magnetic #12;eld. A criterion is obtained for stabilization of the \\sausage

Zakharov, Leonid E.

98

Neutral Beam Injection for Plasma and Magnetic Field Diagnostics  

E-Print Network [OSTI]

Injection for Plasma and Magnetic Field Diagnostics 1 **diagnostic neutral beam injection system for measuring plasmaplasma v . High proton fraction and small divergence is essential for diagnostic

Vainionpaa, Jaakko Hannes; Leung, Ka Ngo; Kwan, Joe W.; Levinton, Fred

2007-01-01T23:59:59.000Z

99

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

100

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

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

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

2014-09-05T23:59:59.000Z

102

Static magnetic field concentration and enhancement using magnetic materials with positive permeability  

E-Print Network [OSTI]

In this paper a novel compressor for static magnetic fields is proposed based on finite embedded transformation optics. When the DC magnetic field passes through the designed device, the magnetic field can be compressed inside the device. After it passes through the device, one can obtain an enhanced static magnetic field behind the output surface of the device (in a free space region). We can also combine our compressor with some other structures to get a higher static magnetic field enhancement in a free space region. In contrast with other devices based on transformation optics for enhancing static magnetic fields, our device is not a closed structure and thus has some special applications (e.g., for controlling magnetic nano-particles for gene and drag delivery). The designed compressor can be constructed by using currently available materials or DC meta-materials with positive permeability. Numerical simulation verifies good performance of our device.

Sun, F

2013-01-01T23:59:59.000Z

103

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

104

Observation of low magnetic field density peaks in helicon plasma  

SciTech Connect (OSTI)

Single density peak has been commonly observed in low magnetic field (<100 G) helicon discharges. In this paper, we report the observations of multiple density peaks in low magnetic field (<100 G) helicon discharges produced in the linear helicon plasma device [Barada et al., Rev. Sci. Instrum. 83, 063501 (2012)]. Experiments are carried out using argon gas with m = +1 right helical antenna operating at 13.56 MHz by varying the magnetic field from 0 G to 100 G. The plasma density varies with varying the magnetic field at constant input power and gas pressure and reaches to its peak value at a magnetic field value of {approx}25 G. Another peak of smaller magnitude in density has been observed near 50 G. Measurement of amplitude and phase of the axial component of the wave using magnetic probes for two magnetic field values corresponding to the observed density peaks indicated the existence of radial modes. Measured parallel wave number together with the estimated perpendicular wave number suggests oblique mode propagation of helicon waves along the resonance cone boundary for these magnetic field values. Further, the observations of larger floating potential fluctuations measured with Langmuir probes at those magnetic field values indicate that near resonance cone boundary; these electrostatic fluctuations take energy from helicon wave and dump power to the plasma causing density peaks.

Barada, Kshitish K.; Chattopadhyay, P. K.; Ghosh, J.; Kumar, Sunil; Saxena, Y. C. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

2013-04-15T23:59:59.000Z

105

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

106

Magnetic-field-induced antiferromagnetism in the Kondo lattice  

E-Print Network [OSTI]

The half-filled Kondo lattice model, augmented by a Zeeman term, serves as a useful model of a Kondo insulator in an applied magnetic field. A variational mean field analysis of this system on a square lattice, backed up ...

Beach, Kevin S. D. (Kevin Stuart David), 1975-

2004-01-01T23:59:59.000Z

107

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.

108

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, Mark E. (Los Alamos, NM); Benicewicz, Brian C. (Los Alamos, NM); Douglas, Elliot P. (Los Alamos, NM)

1998-01-01T23:59:59.000Z

109

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

110

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

111

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

112

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

113

Field quality measurements of a 2-Tesla transmission line magnet  

SciTech Connect (OSTI)

A prototype 2-Tesla superconducting transmission line magnet for future hadron colliders was designed, built and tested at Fermilab. The 1.5 m long, combined-function gradient-dipole magnet has a vertical pole aperture of 20 mm. To measure the magnetic field quality in such a small magnet aperture, a specialized rotating coil of 15.2 mm diameter, 0.69 m long was fabricated. Using this probe, a program of magnetic field quality measurements was successfully performed. Results of the measurements are presented and discussed.

Velev, G.V.; Foster, W.; Kashikhin, V.; Mazur, P.; Oleck, A.; Piekarz, H.; Schlabach, P.; Sylvester, C.; /Fermilab; Wake, M.; /KEK, Tsukuba

2005-09-01T23:59:59.000Z

114

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

115

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

E-Print Network [OSTI]

DEVELOPMENT OF MAGNETIC SEPARATION METHODS OF ANALYSIS: MAGNETIC FIELD FLOW FRACTIONATION A Thesis by JAIME GARCIA-RAMIREZ Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree... 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

1980-01-01T23:59:59.000Z

116

Developments in deep brain stimulation using time dependent magnetic fields  

SciTech Connect (OSTI)

The effect of head model complexity upon the strength of field in different brain regions for transcranial magnetic stimulation (TMS) has been investigated. Experimental measurements were used to verify the validity of magnetic field calculations and induced electric field calculations for three 3D human head models of varying complexity. Results show the inability for simplified head models to accurately determine the site of high fields that lead to neuronal stimulation and highlight the necessity for realistic head modeling for TMS applications.

Crowther, L.J.; Nlebedim, I.C.; Jiles, D.C.

2012-03-07T23:59:59.000Z

117

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

118

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 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.

Lari, Robert J. (Aurora, IL); Praeg, Walter F. (Palos Park, IL); Turner, Larry R. (Naperville, IL); Battles, James E. (Oak Forest, IL); Hull, John R. (Hinsdale, IL); Rote, Donald M. (Lagrange, IL)

1990-01-01T23:59:59.000Z

119

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

120

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

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

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

122

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

123

Brass plasmoid in external magnetic field at different air pressures  

SciTech Connect (OSTI)

The behavior of expanding brass plasmoid generated by 266 nm wavelength of Nd:YAG laser in nonuniform magnetic field at different air pressures has been examined using optical emission spectroscopy and fast imaging of plasma plumes. The splitting of the plasma plumes and enhancement of intensity of Cu I at 510.5 nm in the presence of magnetic field at lower pressures are discussed. The threading and expulsion of the magnetic field lines through the plasmoid are correlated with the ambient pressure. The stoichiometry of the plasma plume is not significantly influenced by the magnetic field; however, the abundance of neutral to ionic species of Cu and Zn is greatly influenced by the magnetic field.

Patel, D. N.; Thareja, Raj K. [Department of Physics, Indian Institute of Technology Kanpur, Kanpur, UP 208016 (India)] [Department of Physics, Indian Institute of Technology Kanpur, Kanpur, UP 208016 (India); Pandey, Pramod K. [WCI-Center for Quantum-Beam Based Radiation Research, Korea Atomic Energy Research Institute, Daojeon (Korea, Republic of)] [WCI-Center for Quantum-Beam Based Radiation Research, Korea Atomic Energy Research Institute, Daojeon (Korea, Republic of)

2013-10-15T23:59:59.000Z

124

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

125

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

126

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. In the absence of dark energy components, magnetic field can favour an accelerating model even if we take a linear relationship between the directional Hubble parameters. In presence of dark energy components in the form of a time varying cosmological constant, the influence of magnetic field is found to be limited.

S. K. Tripathy; K. L. Mahanta

2014-12-10T23:59:59.000Z

127

Magnetic-field sensing coil embedded in ceramic for measuring ambient magnetic field  

DOE Patents [OSTI]

A magnetic pick-up coil for measuring magnetic field with high specific sensitivity, optionally with an electrostatic shield (24), having coupling elements (22) with high winding packing ratio, oriented in multiple directions, and embedded in ceramic material for structural support and electrical insulation. Elements of the coil are constructed from green ceramic sheets (200) and metallic ink deposited on surfaces and in via holes of the ceramic sheets. The ceramic sheets and the metallic ink are co-fired to create a monolithic hard ceramic body (20) with metallized traces embedded in, and placed on exterior surfaces of, the hard ceramic body. The compact and rugged coil can be used in a variety of environments, including hostile conditions involving ultra-high vacuum, high temperatures, nuclear and optical radiation, chemical reactions, and physically demanding surroundings, occurring either individually or in combinations.

Takahashi, Hironori

2004-02-10T23:59:59.000Z

128

Magnetic field in holographic superconductor with dark matter sector  

E-Print Network [OSTI]

Based on the analytical technique the effect of the static magnetic field on the s-wave holographic superconductor with dark matter sector of U(1)-gauge field type coupled to the Maxwell field has been examined. In the probe limit, we obtained the mean value of the condensation operator. The nature of the condensate in an external magnetic field as well as the behaviour of the critical field close to the transition temperature has been revealed. The obtained upturn of the critical field curves as a function of temperature, both in four and five spacetime dimensions, is a fingerprint of the strong coupling approach.

Nakonieczny, L; Wysokinski, K I

2015-01-01T23:59:59.000Z

129

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 b...

Ray, M W; Kandel, S; Möttönen, M; Hall, D S

2014-01-01T23:59:59.000Z

130

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...

131

Color superconductivity in a strong external magnetic field  

E-Print Network [OSTI]

We explore the effects of an applied strong external magnetic field in a three flavor massless color superconductor. The long-range component of the B field that penetrates the superconductor enhances some quark condensates, leading to a different condensation pattern. The external field also reduces the flavor symmetries in the system, and thus it changes drastically the corresponding low energy physics. Our considerations are relevant for the study of highly magnetized compact stars.

Cristina Manuel

2006-07-26T23:59:59.000Z

132

Magnetic Field Restructuring Associated with Two Successive Solar Eruptions  

E-Print Network [OSTI]

We examine two successive flare eruptions (X5.4 and X1.3) on 2012 March 7 in the NOAA active region 11429 and investigate the magnetic field reconfiguration associated with the two eruptions. Using an advanced non-linear force-free field (NLFFF) extrapolation method based on the SDO/HMI vector magnetograms, we obtain a stepwise decrease in the magnetic free energy during the eruptions, which is roughly 20%-30% of the energy of the pre-flare phase. We also calculate the magnetic helicity, and suggest that the changes of the sign of the helicity injection rate might be associated with the eruptions. Through the investigation of the magnetic field evolution, we find that the appearance of the "implosion" phenomenon has a strong relationship with the occurrence of the first X-class flare. Meanwhile, the magnetic field changes of the successive eruptions with implosion and without implosion were well observed.

Wang, Rui; Yang, Zhongwei; Hu, Huidong

2014-01-01T23:59:59.000Z

133

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

E-Print Network [OSTI]

Magnetic anisotropy in Fe-25Cr-12Co-1Si alloy induced by external magnetic field ZHEN Liang( )1 of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China; 2. Department 27599-3255, USA Received 29 June 2006; accepted 15 January 2007 Abstract: Structural and magnetic

Qin, Lu-Chang

134

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

135

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

136

Modeling spin magnetization transport in a spatially varying magnetic field  

E-Print Network [OSTI]

We present a framework for modeling the transport of any number of globally conserved quantities in any spatial configuration and apply it to obtain a model of magnetization transport for spin-systems that is valid in new regimes (including high-polarization). The framework allows an entropy function to define a model that explicitly respects the laws of thermodynamics. Three facets of the model are explored. First, it is expressed as nonlinear partial differential equations that are valid for the new regime of high dipole-energy and polarization. Second, the nonlinear model is explored in the limit of low dipole-energy (semi-linear), from which is derived a physical parameter characterizing separative magnetization transport (SMT). It is shown that the necessary and sufficient condition for SMT to occur is that the parameter is spatially inhomogeneous. Third, the high spin-temperature (linear) limit is shown to be equivalent to the model of nuclear spin transport of Genack and Redfield. Differences among the three forms of the model are illustrated by numerical solution with parameters corresponding to a magnetic resonance force microscopy (MRFM) experiment. A family of analytic, steady-state solutions to the nonlinear equation is derived and shown to be the spin-temperature analog of the Langevin paramagnetic equation and Curie's law. Finally, we analyze the separative quality of magnetization transport, and a steady-state solution for the magnetization is shown to be compatible with Fenske's separative mass transport equation.

Rico A. R. Picone; Joseph L. Garbini; John A. Sidles

2014-08-13T23:59:59.000Z

137

Solar nebula magnetic fields recorded in the Semarkona meteorite  

E-Print Network [OSTI]

  1   Solar nebula magnetic fields recorded in the Semarkona meteorite 1   2   3   Roger R. Fu1*, Benjamin P. Weiss1, Eduardo A. Lima1, Richard J. Harrison2, Xue-Ning Bai3,4, 4   Steven J. Desch5, Denton S. Ebel6, Clement Suavet1...   in the solar nebula. If a stable field was present during cooling, they should have acquired a 57   thermoremanent magnetization (TRM), which can be characterized via paleomagnetic 58   experiments. Besides assessing the role of magnetic fields in disk...

Fu, Roger R.; Weiss, Benjamin P.; Lima, Eduardo A.; Harrison, Richard J.; Bai, Xue-Ning; Desch, Steven J.; Ebel, Denton S.; Suavet, Clement; Wang, Huapei; Glenn, David; Le Sage, David; Kasama, Takeshi; Walsworth, Ronald L.; Kuan, Aaron T.

2014-11-13T23:59:59.000Z

138

Universality of critical magnetic field in holographic superconductor  

E-Print Network [OSTI]

In this letter we study aspects of the holographic superconductors analytically in the presence of a constant external magnetic field. We show that the critical temperature and critical magnetic field can be calculated at nonzero temperature. We detect the Meissner effect in such superconductors. A universal relation between black hole mass $ M$ and critical magnetic field $H_c$ is proposed as $\\frac{H_c}{M^{2/3}}\\leq 0.687365$. We discuss some aspects of phase transition in terms of black hole entropy and the Bekenstein's entropy to energy upper bound.

D. Momeni; R. Myrzakulov

2015-02-11T23:59:59.000Z

139

Heat pipes for use in a magnetic field  

DOE Patents [OSTI]

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

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

1983-07-19T23:59:59.000Z

140

Effects of non-radial magnetic field on measuring magnetic helicity transport across solar photosphere  

E-Print Network [OSTI]

It is generally believed that the evolution of magnetic helicity has a close relationship with solar activity. Before the launch of SDO, earlier studies have mostly used MDI/SOHO line of sight magnetograms and assumed that magnetic fields are radial when calculating magnetic helicity injection rate from photospheric magnetograms. However, this assumption is not necessarily true. Here we use the vector magnetograms and line of sight magnetograms, both taken by HMI/SDO, to estimate the effects of non-radial magnetic field on measuring magnetic helicity injection rate. We find that: 1) The effect of non-radial magnetic field on estimating tangential velocity is relatively small; 2) On estimating magnetic helicity injection rate, the effect of non-radial magnetic field is strong when active regions are observed near the limb and is relatively small when active regions are close to disk center; 3) The effect of non-radial magnetic field becomes minor if the amount of accumulated magnetic helicity is the only conce...

Song, Yongliang

2015-01-01T23:59:59.000Z

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

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

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

; Materials Science 66 The Plasma Magnet for Deep Space Exploration Summary: and Andrews,1991) 12;How Plasma Magnet works Rotating Magnetic Field (RMF) rotates at RMF ce > RMF...

142

Influence of primordial magnetic fields on 21 cm emission  

E-Print Network [OSTI]

Magnetic fields in the early universe can significantly alter the thermal evolution and the ionization history during the dark ages. This is reflected in the 21 cm line of atomic hydrogen, which is coupled to the gas temperature through collisions at high redshifts, and through the Wouthuysen-Field effect at low redshifts. We present a semi-analytic model for star formation and the build-up of a Lyman alpha background in the presence of magnetic fields, and calculate the evolution of the mean 21 cm brightness temperature and its frequency gradient as a function of redshift. We further discuss the evolution of linear fluctuations in temperature and ionization in the presence of magnetic fields and calculate the effect on the 21 cm power spectrum. At high redshifts, the signal is increased compared to the non-magnetic case due to the additional heat input into the IGM from ambipolar diffusion and the decay of MHD turbulence. At lower redshifts, the formation of luminous objects and the build-up of a Lyman alpha background can be delayed by a redshift interval of 10 due to the strong increase of the filtering mass scale in the presence of magnetic fields. This tends to decrease the 21 cm signal compared to the zero-field case. In summary, we find that 21 cm observations may become a promising tool to constrain primordial magnetic fields.

Dominik R. G. Schleicher; Robi Banerjee; Ralf S. Klessen

2008-12-17T23:59:59.000Z

143

Magnetic Moment of Vector Mesons in the Background Field Method  

E-Print Network [OSTI]

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

Frank X. Lee; Scott Moerschbacher; Walter Wilcox

2007-10-11T23:59:59.000Z

144

Dust-Plasma Sheath in an Oblique Magnetic Field  

SciTech Connect (OSTI)

Using numerical simulations of the multi fluid equations the structure of the magnetized sheath near a plasma boundary is studied in the presence of charged dust particles. The dependence of the electron, ion, and dust densities as well as the electrostatic potential, dust charge, and ion normal velocity, on the magnetic field strength and the edge dust number density is investigated.

Foroutan, G.; Mehdipour, H. [Physics Department, Faculty of Science, Sahand University of Technology, Tabriz (Iran, Islamic Republic of)

2008-09-07T23:59:59.000Z

145

Advanced measurements and techniques in high magnetic fields  

SciTech Connect (OSTI)

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

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

1997-07-01T23:59:59.000Z

146

Ferrofluid surface and volume flows in uniform rotating magnetic fields  

E-Print Network [OSTI]

Ferrofluid surface and volume effects in uniform dc and rotating magnetic fields are studied. Theory and corroborating measurements are presented for meniscus shapes and resulting surface driven flows, spin-up flows, and ...

Elborai, Shihab M. (Shihab Mahmoud), 1977-

2006-01-01T23:59:59.000Z

147

Vorticity and magnetic field production in relativistic ideal fluids  

E-Print Network [OSTI]

In the framework of relativistic ideal hydrodynamics, we study the production mechanism for vorticity and magnetic field in relativistic ideal fluids. It is demonstrated that in the uncharged fluids the thermal vorticity will always satisfy the Kelvin's theorem and the circulation must be conserved. However, in the charged fluids, the vorticity and magnetic field can be produced by the interaction between the entropy gradients and the fluid velocity gradients. Especially, in the multiple charged fluids, the vorticity and magnetic field can be produced by the interaction between the inhomogenous charge density ratio and the fluid velocity gradients even if the entropy distribution is homogeneous, which provides another mechanism for the production of vorticity and magnetic field in relativistic plasmas or in the early universe.

Jian-Hua Gao; Bin Qi; Shou-Yu Wang

2015-01-26T23:59:59.000Z

148

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

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

read all about how our DC Field Facility's world-record magnets are powered, take a virtual look at how the many components of this amazing system work together. Click on any...

149

Solar nebula magnetic fields recorded in the Semarkona meteorite  

E-Print Network [OSTI]

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

Fu, Roger Rennan

150

Magnetic Fields and the Triaxiality of Molecular Cloud Cores  

E-Print Network [OSTI]

We make the hypothesis that molecular cloud fragments are triaxial bodies with a large scale magnetic field oriented along the short axis. While consistent with theoretical expectations, this idea is supported by magnetic field strength data, which show strong evidence for flattening along the direction of the mean magnetic field. It is also consistent with early submillimeter polarization data, which show that the projected direction of the magnetic field is often slightly misaligned with the projected minor axis of a molecular cloud core, i.e., the offset angle $\\Psi$ is nonzero. We calculate distributions of $\\Psi$ for various triaxial bodies, when viewed from a random set of viewing angles. The highest viewing probability always corresponds to $\\Psi=0^{\\circ}$, but there is a finite probability of viewing all nonzero $\\Psi$, including even $\\Psi =90^{\\circ}$; the average offset typically falls in the range $10^{\\circ}-30^{\\circ}$ for triaxial bodies most likely to satisfy observational and theoretical constraints.

Shantanu Basu

2000-08-16T23:59:59.000Z

151

Primordial magnetic fields and formation of molecular hydrogen  

E-Print Network [OSTI]

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

Shiv K Sethi; Biman B. Nath; Kandaswamy Subramanian

2008-04-22T23:59:59.000Z

152

Neutron in a Strong Magnetic Field: Finite Volume Effects  

E-Print Network [OSTI]

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

Brian C. Tiburzi

2014-03-04T23:59:59.000Z

153

Error field and magnetic diagnostic modeling for W7-X  

SciTech Connect (OSTI)

The prediction, detection, and compensation of error fields for the W7-X device will play a key role in achieving a high beta (? = 5%), steady state (30 minute pulse) operating regime utilizing the island divertor system [1]. Additionally, detection and control of the equilibrium magnetic structure in the scrape-off layer will be necessary in the long-pulse campaign as bootstrapcurrent evolution may result in poor edge magnetic structure [2]. An SVD analysis of the magnetic diagnostics set indicates an ability to measure the toroidal current and stored energy, while profile variations go undetected in the magnetic diagnostics. An additional set of magnetic diagnostics is proposed which improves the ability to constrain the equilibrium current and pressure profiles. However, even with the ability to accurately measure equilibrium parameters, the presence of error fields can modify both the plasma response and diverter magnetic field structures in unfavorable ways. Vacuum flux surface mapping experiments allow for direct measurement of these modifications to magnetic structure. The ability to conduct such an experiment is a unique feature of stellarators. The trim coils may then be used to forward model the effect of an applied n = 1 error field. This allows the determination of lower limits for the detection of error field amplitude and phase using flux surface mapping. *Research supported by the U.S. DOE under Contract No. DE-AC02-09CH11466 with Princeton University.

Lazerson, Sam A. [PPPL; Gates, David A. [PPPL; NEILSON, GEORGE H. [PPPL; OTTE, M.; Bozhenkov, S.; Pedersen, T. S.; GEIGER, J.; LORE, J.

2014-07-01T23:59:59.000Z

154

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

155

One-way Ponderomotive Barrier in a Uniform Magnetic Field  

SciTech Connect (OSTI)

The possibility of an asymmetric ponderomotive barrier in a nonuniform dc magnetic field by high-frequency radiation near the cyclotron resonance for selected plasma species was contemplated in Physics of Plasmas 11 (November 2004) 5046-5064. Here we show that a similar one-way barrier, which reflects particles incident from one side while transmitting those incident from the opposite side, can be produced also in a uniform magnetic field, entirely due to inhomogeneity of high-frequency drive.

I.Y. Dodin; N.J. Fisch

2005-02-14T23:59:59.000Z

156

Thermoelectric effects in organic conductors in a strong magnetic field  

SciTech Connect (OSTI)

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

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

2007-07-15T23:59:59.000Z

157

Warm inflation in the presence of magnetic fields  

E-Print Network [OSTI]

We study the effects of primordial magnetic fields on the inflationary potential in the context of a warm inflation scenario. The model, based on global supersymmetry with a new-inflation-type potential and a coupling between the inflaton and a heavy intermediate superfield, is already known to preserve the flatness required for slow-roll conditions even after including thermal contributions. Here we show that the magnetic field makes the potential even flatter, retarding the transition and rendering it smoother.

Gabriella Piccinelli; Angel Sanchez; Alejandro Ayala; Ana Julia Mizher

2014-09-08T23:59:59.000Z

158

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

E-Print Network [OSTI]

). An alternative approach to engineering low electric- field-induced magnetic domain switching at room temperaPhase-field simulation of electric-field-induced in-plane magnetic domain switching in magnetic. Phys. Lett. 99, 182510 (2011) Quantum tunneling of the Bloch point in a magnetic film with strong

Chen, Long-Qing

159

Influence of Time-Varying External Magnetic Fields on Trapped Fields in Bulk Superconductors  

E-Print Network [OSTI]

Large, single-grain bulk high-temperature superconductors (HTS) can trap magnetic fields over 17 T below 30 K and up to 3 T at 77 K, and have significant potential to replace permanent magnets, the fields from which are limited to significantly less...

Zou, Jin; Ainslie, Mark D.; Hu, Di; Cardwell, David A.

2014-12-12T23:59:59.000Z

160

Prospects for x-ray polarimetry measurements of magnetic fields in magnetized liner inertial fusion plasmas  

SciTech Connect (OSTI)

Magnetized Liner Inertial Fusion (MagLIF) experiments, where a metal liner is imploded to compress a magnetized seed plasma may generate peak magnetic fields ?10{sup 4} T (100 Megagauss) over small volumes (?10{sup ?10}m{sup 3}) at high plasma densities (?10{sup 28}m{sup ?3}) on 100 ns time scales. Such conditions are extremely challenging to diagnose. We discuss the possibility of, and issues involved in, using polarimetry techniques at x-ray wavelengths to measure magnetic fields under these extreme conditions.

Lynn, Alan G., E-mail: lynn@ece.unm.edu; Gilmore, Mark [Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

2014-11-15T23:59:59.000Z

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


161

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

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

Loss Measurements of a Cable-in-Conduit Conductor with Nb3Sn Strands for the High Field Section of the Series-Connected Hybrid Outsert Coil, IEEE Trans. Appl. Supercond., 19 (3,...

162

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

E-Print Network [OSTI]

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

Bjørk, R

2014-01-01T23:59:59.000Z

163

Gravitational resonance spectroscopy with an oscillating magnetic field gradient in the GRANIT flow through arrangement  

E-Print Network [OSTI]

Gravitational resonance spectroscopy consists in measuring the energy spectrum of bouncing ultracold neutrons above a mirror by inducing resonant transitions between different discrete quantum levels. We discuss how to induce the resonances with a flow through arrangement in the GRANIT spectrometer, excited by an oscillating magnetic field gradient. The spectroscopy could be realized in two distinct modes (so called DC and AC) using the same device to produce the magnetic excitation. We present calculations demonstrating the feasibility of the newly proposed AC mode.

G. Pignol; S. Baessler; V. V. Nesvizhevsky; K. Protasov; D. Rebreyend; A. Yu. Voronin

2014-08-05T23:59:59.000Z

164

Effects of the 9-T magnetic field on MRS photodiode  

SciTech Connect (OSTI)

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

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

2005-10-01T23:59:59.000Z

165

MRS Photodiode, LED and extruded scintillator performance in magnetic field  

SciTech Connect (OSTI)

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

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

2005-05-01T23:59:59.000Z

166

Fluorescent lamp unit with magnetic field generating means  

DOE Patents [OSTI]

A fluorescent lamp unit having a magnetic field generating means for improving the performance of the fluorescent lamp is disclosed. In a preferred embodiment the fluorescent lamp comprises four longitudinally extending leg portions disposed in substantially quadrangular columnar array and joined by three generally U-shaped portions disposed in different planes. In another embodiment of the invention the magnetic field generating means comprises a plurality of permanent magnets secured together to form a single columnar structure disposed within a centrally located region defined by the shape of lamp envelope. 4 figs.

Grossman, M.W.; George, W.A.

1989-08-08T23:59:59.000Z

167

RESOLVED MAGNETIC FIELD MAPPING OF A MOLECULAR CLOUD USING GPIPS  

SciTech Connect (OSTI)

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

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

2012-08-20T23:59:59.000Z

168

Extragalactic Magnetic Field and the Highest Energy Cosmic Rays  

E-Print Network [OSTI]

The strength and spectrum of the extragalactic magnetic field are still unknown. Its measurement would help answer the question of whether galactic fields are purely a primordial relic or were dynamically enhanced from a much smaller cosmological seed field. In this letter, we show that the composition, spectrum, and directional distribution of extragalactic ultrahigh energy cosmic rays with energies above $\\simeq 10^{18}\\ev$ can probe the large scale component of the extragalactic magnetic field below the present observational upper limit of $10^{-9}$ Gauss. Cosmic ray detectors under construction or currently in the proposal stage should be able to test the existence of the extragalactic magnetic fields on scales of a few to tens of Mpc and strengths in the range $\\simeq 10^{-10} - 10^{-9}$ Gauss.

Sangjin Lee; Angela Olinto; Guenter Sigl

1995-08-21T23:59:59.000Z

169

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

SciTech Connect (OSTI)

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

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

2008-01-01T23:59:59.000Z

170

Magnetic field control of the intraband optical absorption in two-dimensional quantum rings  

SciTech Connect (OSTI)

Linear and nonlinear optical absorption coefficients of the two-dimensional semiconductor ring in the perpendicular magnetic field B are calculated within independent electron approximation. Characteristic feature of the energy spectrum are crossings of the levels with adjacent nonpositive magnetic quantum numbers as the intensity B changes. It is shown that the absorption coefficient of the associated optical transition is drastically decreased at the fields corresponding to the crossing. Proposed model of the Volcano disc allows to get simple mathematical analytical results, which provide clear physical interpretation. An interplay between positive linear and intensity-dependent negative cubic absorption coefficients is discussed; in particular, critical light intensity at which additional resonances appear in the total absorption dependence on the light frequency is calculated as a function of the magnetic field and levels' broadening.

Olendski, O., E-mail: oolendski@ksu.edu.sa [King Abdullah Institute for Nanotechnology, King Saud University, P.O. Box 2454, Riyadh 11451 (Saudi Arabia); Barakat, T., E-mail: tbarakat@ksu.edu.sa [Department of Physics, King Saud University, P.O. Box 2454, Riyadh 11451 (Saudi Arabia)

2014-02-28T23:59:59.000Z

171

ALIGNMENT BETWEEN FLATTENED PROTOSTELLAR INFALL ENVELOPES AND AMBIENT MAGNETIC FIELDS  

SciTech Connect (OSTI)

We present 350 {mu}m polarization observations of four low-mass cores containing Class 0 protostars: L483, L1157, L1448-IRS2, and Serp-FIR1. This is the second paper in a larger survey aimed at testing magnetically regulated models for core-collapse. One key prediction of these models is that the mean magnetic field in a core should be aligned with the symmetry axis (minor axis) of the flattened young stellar object inner envelope (aka pseudodisk). Furthermore, the field should exhibit a pinched or hourglass-shaped morphology as gravity drags the field inward toward the central protostar. We combine our results for the four cores with results for three similar cores that were published in the first paper from our survey. An analysis of the 350 {mu}m polarization data for the seven cores yields evidence of a positive correlation between mean field direction and pseudodisk symmetry axis. Our rough estimate for the probability of obtaining by pure chance a correlation as strong as the one we found is about 5%. In addition, we combine together data for multiple cores to create a source-averaged magnetic field map having improved signal-to-noise ratio, and this map shows good agreement between mean field direction and pseudodisk axis (they are within 15 Degree-Sign ). We also see hints of a magnetic pinch in the source-averaged map. We conclude that core-scale magnetic fields appear to be strong enough to guide gas infall, as predicted by the magnetically regulated models. Finally, we find evidence of a positive correlation between core magnetic field direction and bipolar outflow axis.

Chapman, Nicholas L.; Matthews, Tristan G.; Novak, Giles [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Davidson, Jacqueline A. [School of Physics, University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009 (Australia); Goldsmith, Paul F. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, MS 264-782, Pasadena, CA 91109 (United States); Houde, Martin [Department of Physics and Astronomy, University of Western Ontario, London, ON (Canada); Kwon, Woojin; Looney, Leslie W. [Department of Astronomy, University of Illinois, 1002 West Green Street, Urbana, IL 61801 (United States); Li Zhiyun [Astronomy Department, University of Virginia, Charlottesville, VA 22904 (United States); Matthews, Brenda [Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada); Peng Ruisheng [Caltech Submillimeter Observatory, 111 Nowelo Street, Hilo, HI 96720 (United States); Vaillancourt, John E. [SOFIA Science Center, Universities Space Research Association, NASA Ames Research Center, MS 232-11, Moffett Field, CA 94035-0001 (United States); Volgenau, Nikolaus H. [California Institute of Technology, Owens Valley Radio Observatory, Big Pine, CA 93513 (United States)

2013-06-20T23:59:59.000Z

172

Apparatus for storing high magnetic fields having reduced mechanical forces and reduced magnetic pollution  

DOE Patents [OSTI]

The present invention identifies several configurations of conducting elements capable of storing extremely high magnetic fields for the purpose of energy storage or for other uses, wherein forces experienced by the conducting elements and the magnetic field pollution produced at locations away from the configuration are both significantly reduced over those which are present as a result of the generation of such high fields by currently proposed techniques. It is anticipated that the use of superconducting materials will both permit the attainment of such high fields and further permit such fields to be generated with vastly improved efficiency. 15 figures.

Prueitt, M.L.; Mueller, F.M.; Smith, J.L.

1991-04-09T23:59:59.000Z

173

Apparatus for storing high magnetic fields having reduced mechanical forces and reduced magnetic pollution  

DOE Patents [OSTI]

The present invention identifies several configurations of conducting elements capable of storing extremely high magnetic fields for the purpose of energy storage or for other uses, wherein forces experienced by the conducting elements and the magnetic field pollution produced at locations away from the configuration are both significantly reduced over those which are present as a result of the generation of such high fields by currently proposed techniques. It is anticipated that the use of superconducting materials will both permit the attainment of such high fields and further permit such fields to be generated with vastly improved efficiency.

Prueitt, Melvin L. (Los Alamos, NM); Mueller, Fred M. (Los Alamos, NM); Smith, James L. (Los Alamos, NM)

1991-01-01T23:59:59.000Z

174

National High Magnetic Field Laboratory - Site Index  

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

Learning Lab-wide Media and Public Affairs Personnel Search Covariance NMR Metabolomics Web Portal Cryogenics Curricula D DC Field Program Dictionary Directions Gainesville Site...

175

New look at the QCD ground state in a magnetic field  

E-Print Network [OSTI]

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

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

2014-06-13T23:59:59.000Z

176

Ground-state alignment of atoms and ions: New Diagnostics of Astrophysical Magnetic field in diffuse medium  

E-Print Network [OSTI]

We discuss a new technique of studying magnetic fields in diffuse astrophysical media, e.g. interstellar and intergalactic gas/plasma. This technique is based on the angular momentum alignment of atoms and ions in their ground or metastable states. As the life-time of atoms in such states is long, the alignment induced by anisotropic radiation is susceptible to weak magnetic fields ($1{\\rm G}\\gtrsim B\\gtrsim0.1\\mu$G). The alignment reveals itself in terms of the polarization of the absorbed and emitted light. A variety of atoms with fine or hyperfine splitting of the ground or metastable states exhibit the alignment and the resulting polarization degree in some cases exceeds 20%. We show that in the case of absorption the polarization direction is either parallel or perpendicular to magnetic field, while more complex dependencies emerge for the case of emission of aligned atoms. We show that the corresponding studies of magnetic fields can be performed with optical and UV polarimetry. A unique feature of these studies is that they can reveal the 3D orientation of magnetic field. In addition, we point out that the polarization of the radiation arising from the transitions between fine and hyperfine states of the ground level can provide yet another promising diagnostics of magnetic fields, including the magnetic fields in the Early Universe. We mention several cases of interplanetary, circumstellar and interstellar magnetic fields for which the studies of magnetic fields using ground state atomic alignment effect are promising.

Huirong Yan; A. Lazarian

2008-06-23T23:59:59.000Z

177

Quantum field theory in a magnetic field: From quantum chromodynamics to graphene and Dirac semimetals  

E-Print Network [OSTI]

A range of quantum field theoretical phenomena driven by external magnetic fields and their applications in relativistic systems and quasirelativistic condensed matter ones, such as graphene and Dirac/Weyl semimetals, are reviewed. We start by introducing the underlying physics of the magnetic catalysis. The dimensional reduction of the low-energy dynamics of relativistic fermions in an external magnetic field is explained and its role in catalyzing spontaneous symmetry breaking is emphasized. The general theoretical consideration is supplemented by the analysis of the magnetic catalysis in quantum electrodynamics, chromodynamics and quasirelativistic models relevant for condensed matter physics. By generalizing the ideas of the magnetic catalysis to the case of nonzero density and temperature, we argue that other interesting phenomena take place. The chiral magnetic and chiral separation effects are perhaps the most interesting among them. In addition to the general discussion of the physics underlying chira...

Miransky, Vladimir A

2015-01-01T23:59:59.000Z

178

Self-field and magnetic-flux quantum mechanics  

E-Print Network [OSTI]

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

Paul Harris

2005-04-06T23:59:59.000Z

179

Magnetic field diffusion modeling of a small enclosed firing system  

SciTech Connect (OSTI)

Intense magnetic fields exist in the immediate vicinity of a lightning strike (and near power lines). Conducting barriers increase the rise time (and thus decrease the rise rate) interior to the barrier, but typically do not prevent penetration of the magnetic field, since the lightning current fall time may be larger than the barrier diffusion time. Thus, substantial energy is present in the interior field, although the degradation of rise rate makes it more difficult to couple into electrical circuits. This report assesses the threat posed by the diffusive magnetic field to interior components and wire loops (where voltages are induced). Analytical and numerical bounding analyses are carried out on a pill box shaped conducting barrier to develop estimates for the worst case magnetic field threats inside the system. Worst case induced voltages and energies are estimated and compared with threshold charge voltages and energies on the output capacitor of the system. Variability of these quantities with respect to design parameters are indicated. The interior magnetic field and induced voltage estimates given in this report can be used as excitations for more detailed interior and component models.

Warne, L.K.; Merewether, K.O.

1996-01-01T23:59:59.000Z

180

Magnetic Fields of Uranus and Neptune: Metallic Fluid Hydrogen  

E-Print Network [OSTI]

The magnetic fields of the Ice Giant Planets Uranus and Neptune (U/N) are unique in the solar system. Based on a substantial database measured on Earth for representative planetary fluids at representative dynamic pressures up to 200 GPa (2 Mbar) and a few 1000 K, the complex magnetic fields of U/N are (i) probably made primarily by degenerate metallic fluid H (MFH) at or near the crossover from the H-He envelopes to Ice cores at ~100 GPa (Mbar) pressures and normalized radii of ~90% of the radii of U/N; (ii) because those magnetic fields are made relatively close to the surfaces of U/N, non-dipolar fields can be expected; (iii) the Ice cores are most probably a heterogeneous fluid mixture of H, N, O, C, Fe/Ni and silicate-oxides and their mutual reaction products at high pressures and temperatures; (iv) the shapes of the magnetic fields are probably caused by weak coupling between rotational motions of U/N and convective motions of conducting fluids in dynamos that make those magnetic fields. Ironically, the...

Nellis, W J

2015-01-01T23:59:59.000Z

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

Simple basis for hydrogenic atoms in magnetic fields  

SciTech Connect (OSTI)

A field-dependent hydrogenic basis is used to obtain the evolution of the energy spectrum of atoms in strong (approx.10/sup 8/ G) and uniform magnetic fields. The basis allows results to be derived analytically. Numerical values for the first 13 excited states of hydrogen are found to be in very good agreement with much more elaborate calculations of Smith et al. and of Brandi. In addition, the possibility of having a remnant type of degeneracy in the presence of the magnetic field is investigated.

Gallas, J.A.C.

1984-01-01T23:59:59.000Z

182

Local and nonlocal parallel heat transport in general magnetic fields  

SciTech Connect (OSTI)

A novel approach for the study of parallel transport in magnetized plasmas is presented. The method avoids numerical pollution issues of grid-based formulations and applies to integrable and chaotic magnetic fields with local or nonlocal parallel closures. In weakly chaotic fields, the method gives the fractal structure of the devil's staircase radial temperature profile. In fully chaotic fields, the temperature exhibits self-similar spatiotemporal evolution with a stretched-exponential scaling function for local closures and an algebraically decaying one for nonlocal closures. It is shown that, for both closures, the effective radial heat transport is incompatible with the quasilinear diffusion model.

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

2011-01-01T23:59:59.000Z

183

Local and Nonlocal Parallel Heat Transport in General Magnetic Fields  

SciTech Connect (OSTI)

A novel approach for the study of parallel transport in magnetized plasmas is presented. The method avoids numerical pollution issues of grid-based formulations and applies to integrable and chaotic magnetic fields with local or nonlocal parallel closures. In weakly chaotic fields, the method gives the fractal structure of the devil's staircase radial temperature profile. In fully chaotic fields, the temperature exhibits self-similar spatiotemporal evolution with a stretched-exponential scaling function for local closures and an algebraically decaying one for nonlocal closures. It is shown that, for both closures, the effective radial heat transport is incompatible with the quasilinear diffusion model.

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

2011-05-13T23:59:59.000Z

184

Properties of an axially periodic magnetic field in a betatron  

SciTech Connect (OSTI)

It is shown by solving an equation for the vector potential A (r, z) of the magnetic field that under appropriate conditions the focusing properties of a betatron magnetic field are periodic with respect to the z coordinate. Under these conditions there may be several equilibrium orbits lying in parallel planes z = 0, z = z/sub 01/ xxx, z = mz/sub 01/ in the accelerator. An equation is derived for the distance z/sub 01/ between the equilibrium orbit planes for a given orbit radius r/sub 0/ and field decay exponent n/sub 0/. The operation of such accelerators is described.

Zvontsov, A.A.; Filinova, V.A.; Chakhlov, V.L.

1983-07-01T23:59:59.000Z

185

Treating Cancer with Strong Magnetic Fields and Ultrasound  

E-Print Network [OSTI]

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

Dr. Friedwardt Winterberg

2009-06-03T23:59:59.000Z

186

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

SciTech Connect (OSTI)

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

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

2011-07-01T23:59:59.000Z

187

Magnetic field re-arrangement after prominence eruption  

SciTech Connect (OSTI)

It has long been known that magnetic reconnection plays a fundamental role in a variety of solar events. Although mainly invoked in flare problems, large-scale loops interconnecting active regions, evolving coronal hole boundaries, the solar magnetic cycle itself, provide different evidence of phenomena which involve magnetic reconnection. A further example might be given by the magnetic field rearrangement which occurs after the eruption of a prominence. Since most often a prominence reforms after its disappearance and may be observed at about the same position it occupied before erupting, the magnetic field has to undergo a temporary disruption to relax back, via reconnection, to a configuration similar to the previous one. The above sequence of events is best observable in the case of two-ribbon (2-R) flares but most probably is associated with all filament eruptions. Even if the explanation of the magnetic field rearrangement after 2-R flares in terms of reconnection is generally accepted, the lack of a three-dimensional model capable of describing the field reconfiguration, has prevented, up to now, a thorough analysis of its topology as traced by H..cap alpha../x-ray loops. The purpose of the present work is to present a numerical technique which enables one to predict and visualize the reconnected configuration, at any time t, and therefore allows one to make a significant comparison of observations and model predictions throughout the whole process. 5 refs., 3 figs.

Kopp, R.A.; Poletto, G.

1986-01-01T23:59:59.000Z

188

SOLAR MAGNETIC FIELD SIGNATURES IN HELIOSEISMIC SPLITTING COEFFICIENTS  

SciTech Connect (OSTI)

Normal modes of oscillation of the Sun are useful probes of the solar interior. In this work, we use the even-order splitting coefficients to study the evolution of magnetic fields in the convection zone over solar cycle 23, assuming that the frequency splitting is only due to rotation and a large-scale magnetic field. We find that the data are best fit by a combination of a poloidal field and a double-peaked near-surface toroidal field. The toroidal fields are centered at r {sub 0} = 0.999 R {sub sun} and r = 0.996 R {sub sun} and are confined to the near-surface layers. The poloidal field is a dipole field. The peak strength of the poloidal field is 124 +- 17 G. The toroidal field peaks at 380 +- 30 G and 1.4 +- 0.2 kG for the shallower and deeper fields, respectively. The field strengths are highly correlated with surface activity. The toroidal field strength shows a hysteresis-like effect when compared to the global 10.7 cm radio flux. The poloidal field strength shows evidence of saturation at high activity.

Baldner, Charles S.; Basu, Sarbani [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT, 06520-8101 (United States); Antia, H. M. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Larson, Timothy P., E-mail: charles.baldner@yale.ed [Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085 (United States)

2009-11-10T23:59:59.000Z

189

Symmetry Breaking in Graphene Gregory S. Boebinger, National High Magnetic Field Laboratory  

E-Print Network [OSTI]

Symmetry Breaking in Graphene Gregory S. Boebinger, National High Magnetic Field Laboratory DMR. In this experiment, Landau levels in graphene were used to study the breaking of SU(4) symmetry--a higher dimensional states by their spin polarization. It was found that graphene turns into either a spin ferromagnet

Weston, Ken

190

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

E-Print Network [OSTI]

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

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

2003-10-29T23:59:59.000Z

191

Potts models with magnetic field: arithmetic, geometry, and computation  

E-Print Network [OSTI]

We give a sheaf theoretic interpretation of Potts models with external magnetic field, in terms of constructible sheaves and their Euler characteristics. We show that the polynomial countability question for the hypersurfaces defined by the vanishing of the partition function is affected by changes in the magnetic field: elementary examples suffice to see non-polynomially countable cases that become polynomially countable after a perturbation of the magnetic field. The same recursive formula for the Grothendieck classes, under edge-doubling operations, holds as in the case without magnetic field, but the closed formulae for specific examples like banana graphs differ in the presence of magnetic field. We give examples of computation of the Euler characteristic with compact support, for the set of real zeros, and find a similar exponential growth with the size of the graph. This can be viewed as a measure of topological and algorithmic complexity. We also consider the computational complexity question for evaluations of the polynomial, and show both tractable and NP-hard examples, using dynamic programming.

Shival Dasu; Matilde Marcolli

2014-12-26T23:59:59.000Z

192

Electrostatic waves in carbon nanotubes with an axial magnetic field  

SciTech Connect (OSTI)

Based on a linearized hydrodynamic model and within the quasi-static approximation, the dispersion relation of electrostatic waves propagating through single-walled carbon nanotubes subject to an axial magnetic field is theoretically explored. In the classical limit, we obtain two main possible waves which in turn are divided into two branches, a low-frequency acoustical and a high-frequency optical plasmon branch. In the quantum case, we have found that the dispersion relation is substantially modified when the electron wavelength becomes large enough compared to the propagation wavelength of the electrostatic waves in the quantum plasma. We also show that the axial magnetic field manifest itself on the perturbed electron density through the quantum term and gives rise to the propagation of the electrostatic waves within the quantum plasma. As a result, the effect of the magnetic field is pronounced in the plasma dispersion relations in such a way that their curves approach to zero when the magnetic field is weak; and for the strong magnetic field, they asymptotically meet the constant lines.

Abdikian, Alireza [Department of Physics, Malayer University, Malayer 65719-95863 (Iran, Islamic Republic of)] [Department of Physics, Malayer University, Malayer 65719-95863 (Iran, Islamic Republic of); Bagheri, Mehran [Laser and Plasma Research Institute, Shahid Beheshti University, G. C., Evin, Tehran 19835-63113 (Iran, Islamic Republic of)] [Laser and Plasma Research Institute, Shahid Beheshti University, G. C., Evin, Tehran 19835-63113 (Iran, Islamic Republic of)

2013-10-15T23:59:59.000Z

193

Magnetic Field Measurements and Analysis For an Aladdin Dipole Magnet  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: VegetationEquipment Surfaces and InterfacesAdministration -Lowell L.FallU . S .ofField Measurements and

194

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

Broader source: Energy.gov [DOE]

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

195

Proposal for study of $\\pi^{-}$ nucleur collisions in nuclear emulsion exposed in a pulsed magnetic field  

E-Print Network [OSTI]

Proposal for study of $\\pi^{-}$ nucleur collisions in nuclear emulsion exposed in a pulsed magnetic field

CERN. Geneva. SPS Experiments Committee

1980-01-01T23:59:59.000Z

196

The Magnetic Fields of Classical T Tauri Stars  

E-Print Network [OSTI]

We report new magnetic field measurements for 14 classical T Tauri stars (CTTSs). We combine these data with one previous field determination in order to compare our observed field strengths with the field strengths predicted by magnetospheric accretion models. We use literature data on the stellar mass, radius, rotation period, and disk accretion rate to predict the field strength that should be present on each of our stars according to these magnetospheric accretion models. We show that our measured field values do not correlate with the field strengths predicted by simple magnetospheric accretion theory. We also use our field strength measurements and literature X-ray luminosity data to test a recent relationship expressing X-ray luminosity as a function of surface magnetic flux derived from various solar feature and main sequence star measurements. We find that the T Tauri stars we have observed have weaker than expected X-ray emission by over an order of magnitude on average using this relationship. We suggest the cause for this is actually a result of the very strong fields on these stars which decreases the efficiency with which gas motions in the photosphere can tangle magnetic flux tubes in the corona.

Christopher M. Johns-Krull

2007-04-23T23:59:59.000Z

197

A MATHEMATICAL MODEL FOR AN HOURGLASS MAGNETIC FIELD  

SciTech Connect (OSTI)

Starting with a mathematical boundary value problem for the magnetic vector potential in an axisymmetric cylindrical coordinate system, we derive a general solution for any arbitrary current distribution using the method of Green's functions. We use this to derive an analytic form for an hourglass magnetic field pattern created by electrical currents that are concentrated near (but not confined within) the equatorial plane of a cylindrical coordinate system. Our solution is not characterized by a cusp at the equatorial plane, as in previous solutions based on a current sheet. The pattern we derive provides a very good fit to hourglass magnetic field patterns emerging from three-dimensional numerical simulations of core formation, and can in principle be used for source-fitting of observed magnetic hourglass patterns.

Ewertowski, Bartek; Basu, Shantanu, E-mail: basu@uwo.ca [Department of Physics and Astronomy, Western University, London, Ontario N6A 3K7 (Canada)] [Department of Physics and Astronomy, Western University, London, Ontario N6A 3K7 (Canada)

2013-04-10T23:59:59.000Z

198

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

E-Print Network [OSTI]

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

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

2014-04-14T23:59:59.000Z

199

Generation and control of resonance states in crossed magnetic and electric fields  

E-Print Network [OSTI]

A two-dimensional electron system interacting with an impurity and placed in crossed magnetic and electric fields is under investigation. Since it is assumed that an impurity center interacts as an attractive $\\delta$-like potential a renormalization procedure for the retarded Green's function has to be carried out. For the vanishing electric field we obtain a close analytical expression for the Green's function and we find one bound state localized between Landau levels. It is also shown by numerical investigations that switching on the electric field new long-living resonance states localized in the vicinity of Landau levels can be generated.

Katarzyna Krajewska; Jerzy Z. Kaminski

2002-05-17T23:59:59.000Z

200

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

SciTech Connect (OSTI)

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

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

2007-08-27T23:59:59.000Z

Note: This page contains sample records for the topic "magnetic field levels" from the National Library of EnergyBeta (NLEBeta).
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201

Electric and magnetic fields and field derivatives from lightning stepped leaders and first return strokes measured at distances  

E-Print Network [OSTI]

Electric and magnetic fields and field derivatives from lightning stepped leaders and first return; published 5 September 2008. [1] Using electric and magnetic field and field derivative sensors arrayed over-peak width of the stepped-leader/return-stroke electric field waveform; the stepped-leader electric field

Florida, University of

202

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

203

Magnetic Fields in Gamma-Ray Bursts: A Short Review  

E-Print Network [OSTI]

Magnetic fields play a crucial role in the physics of Gamma-Ray Bursts (GRBs). Strong observational evidence indicates that the observed afterglow and most likely the prompt emission arise from synchrotron emission. It is possible that Poynting flux plays an important or even dominant role in the relativistic outflow from the inner engine, but like in other astronomical relativistic jets this suggestion is controversial. Finally, it is likely that magnetic fields larger than $10^{15}$ G occur within GRBs' inner engines and contribute to the acceleration and collimation of the relativistic jets. I review here the GRB fireball model and discuss the role that magnetic fields play in its various components. I suggest that the early afterglow, that reflects the initial interaction of the relativistic jet with its surrounding matter is the best available tool to explore the nature of relativistic outflow in astronomical relativistic jets.

Tsvi Piran

2005-03-02T23:59:59.000Z

204

New dynamo pattern revealed by solar helical magnetic fields  

E-Print Network [OSTI]

Previously unobservable mirror asymmetry of the solar magnetic field -- a key ingredient of the dynamo mechanism which is believed to drive the 11-year activity cycle -- has now been measured. This was achieved through systematic monitoring of solar active regions carried out for more than 20 years at observatories in Mees, Huairou, and Mitaka. In this paper we report on detailed analysis of vector magnetic field data, obtained at Huairou Solar Observing Station in China. Electric current helicity (the product of current and magnetic field component in the same direction) was estimated from the data and a latitude-time plot of solar helicity during the last two solar cycles has been produced. We find that like sunspots helicity patterns propagate equatorwards but unlike sunspot polarity helicity in each solar hemisphere does not change sign from cycle to cycle - confirming the theory. There are, however, two significant time-latitudinal domains in each cycle when the sign does briefly invert. Our findings she...

Zhang, Hongqi; Pevtsov, A; Gao, Yu; Xu, Haiqing; Sokoloff, D D; Kuzanyan, K

2009-01-01T23:59:59.000Z

205

Electron vortex beams in a magnetic field and spin filter  

E-Print Network [OSTI]

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

Debashree Chowdhury; Banasri Basu; Pratul Bandyopadhyay

2015-02-25T23:59:59.000Z

206

Engineering Weyl nodes in Dirac semimetals by a magnetic field  

E-Print Network [OSTI]

We study the phase diagram of a Dirac semimetal in a magnetic field at a nonzero charge density. It is shown that there exists a critical value of the chemical potential at which a first-order phase transition takes place. At subcritical values of the chemical potential the ground state is a gapped state with a dynamically generated Dirac mass and a broken chiral symmetry. The supercritical phase is the normal (gapless) phase with a nontrivial chiral structure: it is a Weyl semimetal with a pair of Weyl nodes for each of the original Dirac points. The nodes are separated by a dynamically induced chiral shift. The direction of the chiral shift coincides with that of the magnetic field and its magnitude is determined by the quasiparticle charge density, the strength of the magnetic field, and the strength of the interaction. The rearrangement of the Fermi surface accompanying this phase transition is described.

E. V. Gorbar; V. A. Miransky; I. A. Shovkovy

2013-10-07T23:59:59.000Z

207

Rotational and magnetic field instabilities in neutron stars  

SciTech Connect (OSTI)

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

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

2014-01-14T23:59:59.000Z

208

Enhancement of accelerating field of microwave cavities by magnetic insulation  

SciTech Connect (OSTI)

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

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

2011-04-15T23:59:59.000Z

209

Quantum field theory in a magnetic field: From quantum chromodynamics to graphene and Dirac semimetals  

E-Print Network [OSTI]

A range of quantum field theoretical phenomena driven by external magnetic fields and their applications in relativistic systems and quasirelativistic condensed matter ones, such as graphene and Dirac/Weyl semimetals, are reviewed. We start by introducing the underlying physics of the magnetic catalysis. The dimensional reduction of the low-energy dynamics of relativistic fermions in an external magnetic field is explained and its role in catalyzing spontaneous symmetry breaking is emphasized. The general theoretical consideration is supplemented by the analysis of the magnetic catalysis in quantum electrodynamics, chromodynamics and quasirelativistic models relevant for condensed matter physics. By generalizing the ideas of the magnetic catalysis to the case of nonzero density and temperature, we argue that other interesting phenomena take place. The chiral magnetic and chiral separation effects are perhaps the most interesting among them. In addition to the general discussion of the physics underlying chiral magnetic and separation effects, we also review their possible phenomenological implications in heavy-ion collisions and compact stars. We also discuss the application of the magnetic catalysis ideas for the description of the quantum Hall effect in monolayer and bilayer graphene, and conclude that the generalized magnetic catalysis, including both the magnetic catalysis condensates and the quantum Hall ferromagnetic ones, lies at the basis of this phenomenon. We also consider how an external magnetic field affects the underlying physics in a class of three-dimensional quasirelativistic condensed matter systems, Dirac semimetals. While at sufficiently low temperatures and zero density of charge carriers, such semimetals are expected to reveal the regime of the magnetic catalysis, the regime of Weyl semimetals with chiral asymmetry is realized at nonzero density...

Vladimir A. Miransky; Igor A. Shovkovy

2015-04-10T23:59:59.000Z

210

Quantum field theory in a magnetic field: From quantum chromodynamics to graphene and Dirac semimetals  

E-Print Network [OSTI]

A range of quantum field theoretical phenomena driven by external magnetic fields and their applications in relativistic systems and quasirelativistic condensed matter ones, such as graphene and Dirac/Weyl semimetals, are reviewed. We start by introducing the underlying physics of the magnetic catalysis. The dimensional reduction of the low-energy dynamics of relativistic fermions in an external magnetic field is explained and its role in catalyzing spontaneous symmetry breaking is emphasized. The general theoretical consideration is supplemented by the analysis of the magnetic catalysis in quantum electrodynamics, chromodynamics and quasirelativistic models relevant for condensed matter physics. By generalizing the ideas of the magnetic catalysis to the case of nonzero density and temperature, we argue that other interesting phenomena take place. The chiral magnetic and chiral separation effects are perhaps the most interesting among them. In addition to the general discussion of the physics underlying chiral magnetic and separation effects, we also review their possible phenomenological implications in heavy-ion collisions and compact stars. We also discuss the application of the magnetic catalysis ideas for the description of the quantum Hall effect in monolayer and bilayer graphene, and conclude that the generalized magnetic catalysis, including both the magnetic catalysis condensates and the quantum Hall ferromagnetic ones, lies at the basis of this phenomenon. We also consider how an external magnetic field affects the underlying physics in a class of three-dimensional quasirelativistic condensed matter systems, Dirac semimetals. While at sufficiently low temperatures and zero density of charge carriers, such semimetals are expected to reveal the regime of the magnetic catalysis, the regime of Weyl semimetals with chiral asymmetry is realized at nonzero density...

Vladimir A. Miransky; Igor A. Shovkovy

2015-03-02T23:59:59.000Z

211

Electric and magnetic field exposure associated with electric blankets  

SciTech Connect (OSTI)

electric blankets may be important contributors to the public's overall exposure to 60 Hz electric and magnetic fields (EMFs) since they are common appliances that are used close to the body for long periods of time. This report describes a series of experimental and computer analyses characterizing various aspects of EMF exposure from electric blankets in use prior to Fall 1990. Almost of electric blankets were found to use on/off controllers with cycle periods of minutes. Calculations of magnetic fields within the body show that, when blankets are heating, flux densities averaged over the whole body range from 15--33 mG during the on'' cycle with typical values of 22 mG. Duty cycles are predicted to vary widely from user-to-user, with typical values of perhaps 40%. Given typical blanket usage patterns, the long-term body-averaged magnetic field exposure from blankets is expected to be comparable to that form other EMF sources for a significant fraction of the blanket-using population. No significant differences were found between time-averaged magnetic field exposures from blankets with metal alloy and plastic polymer heating elements. Blankets with alloy and polymer heating elements did differ significantly in electric field exposure. Calculations show that the unperturbed field 5 cm above flat blankets range from 60--150 V/m for alloy heating cables and unperturbed field 5 cm above flat blankets range from 60--150 V/m for alloy heating cables and 10--40 V/m polymer cables. Starting in Fall 1990, electric blanket manufactures introduced new designs that produce much smaller magnetic fields. These are expected to replace the current in-use stock at a rate of 10--15% per year.

Florig, H.K.; Hoburg, J.F. (Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Engineering and Public Policy)

1991-12-01T23:59:59.000Z

212

Synthesis and simulation of a two-level magnetic control system for tokamak-reactor plasma  

SciTech Connect (OSTI)

Synthesis and simulation of a hierarchical (two-level) magnetic system for controlling a tokamakreactor plasma throughout the entire divertor discharge stage, including the plasma current ramp-up phase, are carried out. The plasma vertical velocity is stabilized about zero by using a proportional controller in a scalar control loop. The gain of the controller-the coefficient that ensures the required stability margins-is found by using a second-order linear model constructed by solving the identification problem on the basis of numerical experiments carried out with the DINA plasmophysical computer code. The internal cascade (the lower level of the system) for tracking the scenario currents in the poloidal magnetic field coils is synthesized by using the complete dynamic channel decoupling method. The external cascade (the upper level of the system) for tracking the plasma current and shape is synthesized by using the method of pseudoseparation of the control channels and the multidimensional diagonal proportional-integral controller, with proportional, integrating, and double integrating units connected in parallel in each channel. In the hierarchical control system, the lower level (the internal cascade) is subordinated to the upper level (the external cascade). The external cascade acts on the internal one by the signals that set the required currents in the coils of the central solenoid and of the poloidal magnetic field in order to ensure the required plasma current and shape in accordance with the output signals from the plant, which are transmitted through the vector feedback channel. The lower level is aimed exclusively at tracking the reference inputs by tracking the currents in the control coils. An operating mode of the system under the conditions of current saturation in the control coils is proposed and implemented. Results are presented from numerical simulations of the two-level (cascade) control system for reference scenario no. 2 of the ITER database (www.iter.org) with the DINA nonlinear code.

Mitrishkin, Yu. V. [Russian Academy of Sciences, V.A. Trapeznikov Institute of Control Sciences (Russian Federation); Korostelev, A. Ya. [Bauman Moscow State Technical University (Russian Federation); Dokuka, V. N.; Khayrutdinov, R. R. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

2011-04-15T23:59:59.000Z

213

Strict deformation quantization for a particle in a magnetic field  

SciTech Connect (OSTI)

Recently, we introduced a mathematical framework for the quantization of a particle in a variable magnetic field. It consists in a modified form of the Weyl pseudodifferential calculus and a C*-algebraic setting, these two points of view being isomorphic in a suitable sense. In the present paper we leave Planck's constant vary, showing that one gets a strict deformation quantization in the sense of Rieffel. In the limit ({Dirac_h}/2{pi}){yields}0 one recovers a Poisson algebra induced by a symplectic form defined in terms of the magnetic field.

Mantoiu, Marius; Purice, Radu [Institute of Mathematics ''Simion Stoilow'' of the Romanian Academy, P.O. Box 1-764, Bucarest, RO-014700 (Romania)

2005-05-01T23:59:59.000Z

214

Utilizing Nitrogen Vacancy Centers to measure oscillating magnetic fields  

E-Print Network [OSTI]

We show how nitrogen vacancy (NV) centers can be used to determine the amplitude, phase and frequency of unknown weak monochromatic and multichromatic oscillating magnetic fields using only the periodic dynamical decoupling (PDD) and Carr-Purcell-Meiboom-Gill (CPMG) sequences. The effect of decoherence on the measurement of the magnetic field parameters is explicitly analyzed, and we take into account the fact that different pulse sequences suppress decoherence to different extents. Since the sensitivity increases with increasing sensing time while it decreases due to decoherence, we use the Fisher information matrix in order to optimize the number of pulses that should be used.

Adam Zaman Chaudhry

2014-04-11T23:59:59.000Z

215

Laser-driven platform for generation and characterization of strong quasi-static magnetic fields  

E-Print Network [OSTI]

Quasi-static magnetic-fields up to $800\\,$T are generated in the interaction of intense laser pulses (500J, 1ns, 10^{17}W/cm^2) with capacitor-coil targets of different materials. The reproducible magnetic-field was consistently measured by three independent diagnostics: GHz-bandwidth inductor pickup coils (B-dot probes), Faraday rotation of polarized optical laser light and proton beam-deflectometry. The field rise time is consistent with the laser pulse duration, and it has a dipole-like distribution over a characteristic volume of 1mm^3, which is coherent with theoretical expectations. These results demonstrate a very efficient conversion of the laser energy into magnetic fields, thus establishing a robust laser-driven platform for reproducible, well characterized, generation of quasi-static magnetic fields at the kT-level, as well as for magnetization and accurate probing of high-energy-density samples driven by secondary powerful laser or particle beams.

Santos, J J; Giuffrida, L; Forestier-Colleoni, P; Fujioka, S; Zhang, Z; Korneev, Ph; Bouillaud, R; Dorard, S; Batani, D; Chevrot, M; Cross, J; Crowston, R; Dubois, J -L; Gazave, J; Gregori, G; d'Humières, E; Hulin, S; Ishihara, K; Kojima, S; Loyez, E; Marquès, J -R; Morace, A; Nicolaï, Ph; Peyrusse, O; Poyé, A; Raffestin, D; Ribolzi, J; Roth, M; Schaumann, G; Serres, F; Tikhonchuk, V T; Vacar, Ph; Woolsey, N

2015-01-01T23:59:59.000Z

216

Ultra-low field nuclear magnetic resonance and magnetic resonance imaging to discriminate and identify materials  

DOE Patents [OSTI]

An ultra-low magnetic field NMR system can non-invasively examine containers. Database matching techniques can then identify hazardous materials within the containers. Ultra-low field NMR systems are ideal for this purpose because they do not require large powerful magnets and because they can examine materials enclosed in conductive shells such as lead shells. The NMR examination technique can be combined with ultra-low field NMR imaging, where an NMR image is obtained and analyzed to identify target volumes. Spatial sensitivity encoding can also be used to identify target volumes. After the target volumes are identified the NMR measurement technique can be used to identify their contents.

Kraus, Robert H. (Los Alamos, NM); Matlashov, Andrei N. (Los Alamos, NM); Espy, Michelle A. (Los Alamos, NM); Volegov, Petr L. (Los Alamos, NM)

2010-03-30T23:59:59.000Z

217

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

E-Print Network [OSTI]

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

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

2014-07-10T23:59:59.000Z

218

Heat pulse propagation in chaotic 3-dimensional magnetic fields  

E-Print Network [OSTI]

Heat pulse propagation in $3$-D chaotic magnetic fields is studied by solving the parallel heat transport equation using a Lagrangian-Green's function (LG) method. The LG method provides an efficient and accurate technique that circumvents limitations of finite elements and finite difference methods. The main two problems addressed are: (i) The dependence of the radial transport on the magnetic field stochasticity (controlled by the amplitude of the perturbation, $\\epsilon$); and (ii) The role of reversed shear configurations on pulse propagation. In all the cases considered there are no magnetic flux surfaces. However, radial transport is observed to depend strongly on $\\epsilon$ due to the presence of high-order magnetic islands and Cantori that act as quasi-transport barriers that preclude the radial penetration of heat pulses within physically relevant time scale. The dependence of the magnetic field connection length, $\\ell_B$, on $\\epsilon$ is studied in detail. The decay rate of the temperature maximum, $\\langle T \\rangle_{max}(t)$, the time delay of the temperature response as function of the radius, $\\tau$, and the radial heat flux $\\langle {{\\bf q}\\cdot {\\hat e}_\\psi} \\rangle$, are also studied as functions of the magnetic field stochasticity and $\\ell_B$. In all cases, the scaling of $\\langle T \\rangle_{max}$ with $t$ transitions from sub-diffusive, $\\langle T \\rangle_{max} \\sim t^{-1/4}$, at short times ($\\chi_\\parallel t 10^5$). A strong dependence on $\\epsilon$ is also observed on $\\tau$ and $\\langle {{\\bf q}\\cdot {\\hat e}_\\psi} \\rangle$. The radial propagation of pulses in fully chaotic fields considerably slows down in the shear reversal region and, as a result, $\\tau$, in reversed shear configurations is an order of magnitude longer than the one in monotonic $q$-profiles.

D. del-Castillo-Negrete; D. Blazevski

2014-09-10T23:59:59.000Z

219

Nuclear magnetic resonances in weak fields  

E-Print Network [OSTI]

' The snalInr 30. voltages necessary in this case would allow the use of parallel banks of batteries, which should increase the stability of the cux xwnt. Lf batteries are used as a ycwsr source, no. 6 wire should be a convenient siss for prodcci...&g fields uy to 106 gauss in a sole noid of the dinensions used here. Pour banks of batterissx each bank containing five batteries in serissx should pxxxvide ~te stabili RIGDIILATTOM FXELUi 'Ae two wain difficulties with the pxesent nodulation scheme...

Mitchell, Richard Warren

1953-01-01T23:59:59.000Z

220

Magnetic field of Josephson vortices outside superconductors  

SciTech Connect (OSTI)

We consider the structure of Josephson vortices approaching the junction boundary with vacuum in large-area Josephson junctions with the Josephson length {lambda}{sub J} large relative to the London penetration depth {lambda}{sub L}. Using the stability argument for one-dimensional solitons with respect to two-dimensional perturbations, it is shown that on the scale {lambda}{sub J}, the Josephson vortices do not spread near the boundary in the direction of the junction. The field distribution in vacuum due to the Josephson vortex is evaluated, the information needed for the scanning superconducting quantum interference device microscopy.

Kogan, V.G.; Dobrovitski, V.V.

2008-04-30T23:59:59.000Z

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

Crystal-Field Splitting and Giant Negative Magnetization in  

SciTech Connect (OSTI)

Bimetallic oxalates are a class of layered organic magnets with transi- tion metals M(II) and M'(III) coupled by oxalate molecules in an open honeycomb structure. Of particular interest are the Fe(II)Fe(III) bimetal- lic compounds, which are ferrimagnetically ordered below a transition temperature that ranges from 30 to 48 K, depending on the cation that separates the layers. In small magnetic fields, several of these compounds exhibit giant negative magnetization below a compensation temperature of roughly 2/3 Tc. By studying the behavior of the Kramer's doublet ground state produced by the crystal-field splitting and constructing a reduced Hamiltonian that includes both exchange and spin-orbit and in- teractions, we can explain all of the important behavior of this class of materials: the stability of magnetic order in two dimensions and the existence of magnetic compensation in samples with high transition tem- peratures. We also provide several new predictions for the spin-wave gap and the optical flipping of the magnetic moment.

Fishman, Randy Scott [ORNL; Reboredo, Fernando A [ORNL

2007-01-01T23:59:59.000Z

222

Screening magnetic fields by superconductors: A simple model  

SciTech Connect (OSTI)

We introduce a simple approach to evaluate the magnetic field distribution around superconducting samples, based on the London equations; the elementary variable is the vector potential. This procedure has no adjustable parameters, only the sample geometry and the London length, ?, determine the solution. This approach was validated by comparing the induction field calculated to the one measured above MgB{sub 2} disks of different diameters, at 20?K and for applied fields lower than 0.4?T. The model can be applied if the flux line penetration inside the sample can be neglected when calculating the induction field distribution outside the superconductor. We conclude by showing on a cup-shape geometry how one can design a magnetic shield satisfying a specific constraint.

Caputo, J.-G., E-mail: caputo@insa-rouen.fr [Laboratoire de Mathématiques, INSA de Rouen, Avenue de l'Université, 76801 Saint-Etienne du Rouvray (France); Gozzelino, L.; Laviano, F.; Ghigo, G.; Gerbaldo, R. [Department of Applied Science and Technology, Politecnico di Torino, 10129, Torino (Italy); Noudem, J.; Thimont, Y.; Bernstein, P. [CRISMAT/LUSAC, Physics Department, Université de Caen (France)

2013-12-21T23:59:59.000Z

223

MISALIGNMENT OF MAGNETIC FIELDS AND OUTFLOWS IN PROTOSTELLAR CORES  

SciTech Connect (OSTI)

We present results of {lambda}1.3 mm dust-polarization observations toward 16 nearby, low-mass protostars, mapped with {approx}2.''5 resolution at CARMA. The results show that magnetic fields in protostellar cores on scales of {approx}1000 AU are not tightly aligned with outflows from the protostars. Rather, the data are consistent with scenarios where outflows and magnetic fields are preferentially misaligned (perpendicular), or where they are randomly aligned. If one assumes that outflows emerge along the rotation axes of circumstellar disks, and that the outflows have not disrupted the fields in the surrounding material, then our results imply that the disks are not aligned with the fields in the cores from which they formed.

Hull, Charles L. H.; Plambeck, Richard L.; Bower, Geoffrey C.; Heiles, Carl; Meredith Hughes, A. [Astronomy Department and Radio Astronomy Laboratory, University of California, Berkeley, CA 94720-3411 (United States); Bolatto, Alberto D.; Jameson, Katherine; Mundy, Lee; Pound, Marc W. [Astronomy Department and Laboratory for Millimeter-wave Astronomy, University of Maryland, College Park, MD 20742 (United States); Carpenter, John M.; Lamb, James W.; Pillai, Thushara [Department of Astronomy, California Institute of Technology, 1200 E. California Blvd., MC 249-17, Pasadena, CA 91125 (United States); Crutcher, Richard M.; Hakobian, Nicholas S.; Kwon, Woojin; Looney, Leslie W. [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W Green Street, Urbana, IL 61801 (United States); Fiege, Jason D.; Franzmann, Erica [Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB R3T 2N2 (Canada); Houde, Martin [Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada); Matthews, Brenda C., E-mail: chat@astro.berkeley.edu [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Rd., Victoria, BC V8P 5C2 (Canada); and others

2013-05-10T23:59:59.000Z

224

Plasma Equilibrium in a Magnetic Field with Stochastic Regions  

SciTech Connect (OSTI)

The nature of plasma equilibrium in a magnetic field with stochastic regions is examined. It is shown that the magnetic differential equation that determines the equilibrium Pfirsch-Schluter currents can be cast in a form similar to various nonlinear equations for a turbulent plasma, allowing application of the mathematical methods of statistical turbulence theory. An analytically tractable model, previously studied in the context of resonance-broadening theory, is applied with particular attention paid to the periodicity constraints required in toroidal configurations. It is shown that even a very weak radial diffusion of the magnetic field lines can have a significant effect on the equilibrium in the neighborhood of the rational surfaces, strongly modifying the near-resonant Pfirsch-Schluter currents. Implications for the numerical calculation of 3D equilibria are discussed

J.A. Krommes and Allan H. Reiman

2009-04-23T23:59:59.000Z

225

Ferrofluid aggregates phase transitions in the planar magnetic field  

E-Print Network [OSTI]

The influence of the cyclic heating and cooling on properties of the aggregates (aka "ferrofluid clusters") in a ferrofluid, which made on the basis of magnetite nanoparticles, are investigated. The heating of the ferrofluid layer with such aggregates leads to equalization of the concentration between high- and low-concentrated phases. The temperature of the equalization of the phase concentrations was determined at different values of an external constant magnetic field, which was applied parallel to the layer of the ferrofluid. The temperature of the destruction of a periodic structure of the magnetic aggregates, which were formed during cooling of a homogeneous phase of the ferrofluid, was obtained at the different values of the applied external magnetic field.

V. F. Kovalenko; M. V. Petrychuk; B. M. Tanygin; S. I. Shulyma

2014-04-21T23:59:59.000Z

226

MAGNETIC FIELDS AND THE OUTER ROTATION CURVE OF M31  

SciTech Connect (OSTI)

Recent observations of the rotation curve of M31 show a rise of the outer part that cannot be understood in terms of standard dark matter models or perturbations of the galactic disk by M31's satellites. Here, we propose an explanation of this dynamical feature based on the influence of the magnetic field within the thin disk. We have considered standard mass models for the luminous mass distribution, a Navarro-Frenk-White model to describe the dark halo, and we have added up the contribution to the rotation curve of a magnetic field in the disk, which is described by an axisymmetric pattern. Our conclusion is that a significant improvement of the fit in the outer part is obtained when magnetic effects are considered. The best-fit solution requires an amplitude of {approx}4 {mu}G with a weak radial dependence between 10 and 38 kpc.

Ruiz-Granados, B.; Rubino-Martin, J. A. [Instituto de Astrofisica de Canarias (IAC), E-38200, La Laguna, Tenerife (Spain); Florido, E.; Battaner, E. [Departamento Fisica Teorica y del Cosmos, Universidad de Granada, Granada (Spain)

2010-11-01T23:59:59.000Z

227

Mathematical Modeling of Magnetic Field Profiles in Superconductors  

E-Print Network [OSTI]

Mathematical Modeling of Magnetic Field Profiles in Superconductors Michael Lindstrom, Brian Wetton, Rob Kiefl March 1, 2011 Abstract One of the defining characteristics of a superconductor is the Meiss results. 1 Introduction to the Problem and the Model Superconductors are materials which exhibit a phase

Wetton, Brian

228

Massive disk outflows mediated by extreme magnetic fields  

E-Print Network [OSTI]

We argue that magnetic fields amplified within a very high accretion-rate disk around main sequence stars can lead to the formation of massive bipolar outflows that can remove most of the disk's mass and energy. This efficient directional removal of energy and mass allows the high accretion-rate disk to be built. We construct thick disks where the magnetic fields are amplified by an Alpha-Omega dynamo in the disk, bringing the fluctuating components of the magnetic field to be much stronger than the large-scale component. By examining the possible activity of the magnetic fields we conclude that main sequence stars can accrete mass at very high rates, up to 0.01Mo/yr for solar type stars, and up to 1Mo/yr for very massive stars. Such energetic outflows can account for the powering of some eruptive objects, such as merging main sequence stars, major eruptions of luminous blue variables, such as the Great Eruption of Eta Carinae, and other intermediate luminosity optical transients (ILOTs; Red Novae; Red Transi...

Shiber, Sagiv; Soker, Noam

2015-01-01T23:59:59.000Z

229

Triggering for Magnetic Field Measurements of the LCLS Undulators  

SciTech Connect (OSTI)

A triggering system for magnetic field measurements of the LCLS undulators has been built with a National Instruments PXI-1002 and a Xylinx FPGA board. The system generates single triggers at specified positions, regardless of encoder sensor jitter about a linear scale.

Hacker, Kirsten

2010-12-13T23:59:59.000Z

230

Lesson Summary Students will learn about the magnetic fields of  

E-Print Network [OSTI]

Lesson Summary Students will learn about the magnetic fields of the Sun and Earth. This activity if they have learned them in another context and you can remind them about those lessons in this activity minutes 1. Read and review the lesson plan 2. Gather required materials 3. Form student teams Exploring

Mojzsis, Stephen J.

231

A linear helicon plasma device with controllable magnetic field gradient  

SciTech Connect (OSTI)

Current free double layers (CFDLs) are localized potential structures having spatial dimensions - Debye lengths and potential drops of more than local electron temperature across them. CFDLs do not need a current for them to be sustained and hence they differ from the current driven double layers. Helicon antenna produced plasmas in an expanded chamber along with an expanding magnetic field have shown the existence of CFDL near the expansion region. A helicon plasma device has been designed, fabricated, and installed in the Institute for Plasma Research, India to study the role of maximum magnetic field gradient as well as its location with respect to the geometrical expansion region of the chamber in CFDL formation. The special feature of this machine consisting of two chambers of different radii is its capability of producing different magnetic field gradients near the physical boundary between the two chambers either by changing current in one particular coil in the direction opposite to that in other coils and/or by varying the position of this particular coil. Although, the machine is primarily designed for CFDL experiments, it is also capable of carrying out many basic plasma physics experiments such as wave propagation, wave coupling, and plasma instabilities in a varying magnetic field topology. In this paper, we will present the details of the machine construction, its specialties, and some preliminary results about the production and characterization of helicon plasma in this machine.

Barada, Kshitish K.; Chattopadhyay, P. K.; Ghosh, J.; Kumar, Sunil; Saxena, Y. C. [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

2012-06-15T23:59:59.000Z

232

Constraining Cosmic Magnetic Fields by a Measurement of  

E-Print Network [OSTI]

. . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 7 Energy-Energy-Correlations 51 7.1 Definition of Energy-EnergyConstraining Cosmic Magnetic Fields by a Measurement of Energy-Energy-Correlations with the Pierre Ultra High Energy Cosmic Rays 3 2.1 Cosmic Rays with Energies below 4 Ee

Erdmann, Martin

233

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

E-Print Network [OSTI]

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

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

2014-09-24T23:59:59.000Z

234

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

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

rotation profile 12;The solar rotation profile 12;Magnetic field generation Nature of solar dynamo... Origin and rise of large-scale magnetic structures ... Source:...

235

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

DOE Patents [OSTI]

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

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

2010-04-13T23:59:59.000Z

236

Producing Magnetar Magnetic Fields in the Merger of Binary Neutron Stars  

E-Print Network [OSTI]

The merger of binary neutron stars (BNSs) can lead to large amplifications of the magnetic field due to the development of turbulence and instabilities in the fluid, such as the Kelvin-Helmholtz shear instability, which drive small scale dynamo activity. In order to properly resolve such instabilities and obtain the correct magnetic field amplification, one would need to employ resolutions that are currently unfeasible in global general relativistic magnetohydrodynamic (GRMHD) simulations of BNS mergers. Here we present a subgrid model that allows global simulations to take into account the small scale amplification of the magnetic field which is caused by development of turbulence during BNS mergers. Assuming dynamo saturation, we show that magnetar-level fields ($\\sim 10^{16}\\,{\\rm G}$) can be easily reached and should therefore be expected from the merger of magnetized BNSs. The total magnetic energy can reach values up to $\\sim 10^{51}\\,{\\rm erg}$ and the post-merger remnant can therefore emit strong electromagnetic signals and possibly produce short gamma-ray bursts.

Bruno Giacomazzo; Jonathan Zrake; Paul Duffell; Andrew I. MacFadyen; Rosalba Perna

2014-09-30T23:59:59.000Z

237

Cold collisions of PH ({sup 3}{Sigma}{sup -}) with helium in magnetic fields  

SciTech Connect (OSTI)

A theoretical investigation of the He-PH ({sup 3}{Sigma}{sup -}) complex is presented. We perform ab initio calculations of the interaction potential energy surface and discuss its error bounds with relevance to cold collisions, and we carry out accurate calculations of bound energy levels of the complex including the molecular fine structure and magnetic-field effect. We find the potential has two shallow minima and supports ten and 13 bound levels in complex with {sup 3}He and {sup 4}He, respectively. Based on the potential the quantum scattering calculations are then implemented for elastic and inelastic cross sections of the magnetically trappable low-field-seeking state of PH ({sup 3}{Sigma}{sup -}) in collision with {sup 3}He atom. The cold-collision properties and the influence of the external magnetic field as well as the effect of the uncertainty of interaction potential on the collisionally induced Zeeman relaxation are explored and discussed in detail. The ratio of elastic to inelastic cross sections is large over a wide range of collision energy, magnetic field, and scaling factor of the potential, so that helium buffer-gas loading and evaporative cooling of PH is a good prospect.

Feng, Eryin; Yu, Chunhua; Sun, Chunyan; Shao, Xi; Huang, Wuying [Department of Physics, Anhui Normal University, Wuhu 241000 (China)

2011-12-15T23:59:59.000Z

238

MAGNETIC FIELD CONFINEMENT IN THE SOLAR CORONA. II. FIELD-PLASMA INTERACTION B. Fornberg,2  

E-Print Network [OSTI]

MAGNETIC FIELD CONFINEMENT IN THE SOLAR CORONA. II. FIELD-PLASMA INTERACTION N. Flyer,1 B. Fornberg numerically to generate a continuum of solutions with two parameters to control the total azimuthal flux from the study to the solar corona and the energetics of coronal mass ejections and flares. Subject

Fornberg, Bengt

239

Apparatus for unilateral generation of a homogeneous magnetic field  

DOE Patents [OSTI]

An apparatus for unilaterally producing a substantially homogeneous magnetic field. The apparatus includes two circular electromagnet coils, a small coil and a large coil, which are coaxial with one another and which are separated by a distance equal to one-half the difference in the radius of the two coils. By appropriate selection of electrical currents, which are passed through the coil in opposite directions, a region of homogeneous magnetic field is formed. This region is centered on the common axis of the two coils, at a point on the axis which is at a distance from the small coil equal to one-half the radius of the small coil, and which is on the opposite side of the small coil from the large coil. The apparatus has particular application in the field of diagnostic medical NMR and other NMR applications.

Fukushima, Eiichi (Los Alamos, NM); Rath, Alan R. (San Diego, CA); Roeder, Stephen B. W. (La Mesa, CA)

1988-01-01T23:59:59.000Z

240

Apparatus for unilateral generation of a homogeneous magnetic field  

DOE Patents [OSTI]

An apparatus for unilaterally producing a substantially homogeneous magnetic field. The apparatus includes two circular electromagnet coils, a small coil and a large coil, which are coaxial with one another and which are separated by a distance equal to one-half the difference in the radius of the two coils. By appropriate selection of electrical currents, which are passed through the coils in opposite directions, a region of homogeneous magnetic field is formed. This region is centered on the common axis of the two coils, at a point on the axis which is at a distance from the small coil equal to one-half the radius of the small coil, and which is on the opposite side of the small coil from the large coil. The apparatus has particular application in the field of diagnostic medical NMR and other NMR applications.

Fukushima, E.; Rath, A.R.; Roeder, S.B.W.

1984-05-01T23:59:59.000Z

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

Faraday Rotation Observations of Magnetic Fields in galaxy Clusters  

E-Print Network [OSTI]

The presence of magnetic fields in the intracluster medium in clusters of galaxies has been revealed through several different observational techniques. These fields may be dynamically important in clusters as they will provide additional pressure support to the intracluster medium as well as inhibit transport mechanisms such as thermal conduction. Here, we review the current observational state of Faraday rotation measure studies of the cluster fields. The fields are generally found to be a few to 10 microG in non-cooling core clusters and ordered on scales of 10-20 kpc. Studies of sources at large impact parameters show that the magnetic fields extend from cluster cores to radii of at least 500 kpc. In central regions of cooling core systems the field strengths are often somewhat higher (10-40 microG) and appear to be ordered on smaller scales of a few to 10 kpc. We also review some of the recent work on interpreting Faraday rotation measure observations through theory and numerical simulations. These techniques allow us to build up a much more detailed view of the strength and topology of the fields.

Tracy E. Clarke

2004-12-10T23:59:59.000Z

242

Quantum Mechanics with a Momentum-Space Artificial Magnetic Field  

E-Print Network [OSTI]

The Berry curvature is a geometrical property of an energy band which acts as a momentum space magnetic field in the effective Hamiltonian describing single-particle quantum dynamics. We show how this perspective may be exploited to study systems directly relevant to ultracold gases and photonics. Given the exchanged roles of momentum and position, we demonstrate that the global topology of momentum space is crucially important. We propose an experiment to study the Harper-Hofstadter Hamiltonian with a harmonic trap that will illustrate the advantages of this approach and that will also constitute the first realization of magnetism on a torus.

Hannah M. Price; Tomoki Ozawa; Iacopo Carusotto

2014-11-19T23:59:59.000Z

243

Cyclotron dynamics of interacting bosons in artificial magnetic fields  

E-Print Network [OSTI]

We study theoretically quantum dynamics of interacting bosons in artificial magnetic fields as engineered in recent ultracold atomic experiments, where quantum cyclotron orbital motion has been observed. With exact numerical simulations and perturbative analyses, we find that interactions induce damping in the cyclotron motion. The damping time is found to be dependent on interaction and tunneling strengths monotonically, while its dependence on magnetic flux is non-monotonic. Sufficiently strong interactions would render bosons dynamically localized inhibiting the cyclotron motion. The damping predicted by us can be construed as an interaction-induced quantum decoherence of the cyclotron motion.

Xiaopeng Li; S. Das Sarma

2014-06-24T23:59:59.000Z

244

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

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

Hybrid Magnet? Now Playing: What's a Hybrid Magnet? Enable Javascript and Flash to stream the Magnet Minute Scott Hannahs Associated Links The World's Strongest Magnet (audio...

245

Use of High Magnetic Field to Control Microstructural Evolution in Metallic and Magnetic Materials  

SciTech Connect (OSTI)

The Amendment 1, referred to as Phase 2, to the original CRADA NFE-06-00414 added tasks 3 through 7 to the original statement of work that had two main tasks that were successfully accomplished in Phase 1 of this project. In this Phase 2 CRADA extension, extensive research and development activities were conducted using high magnetic field processing effects for the purpose of manipulating microstructure in the SAE 5160 steel to refine grain size isothermally and to develop nanocrystalline spacing pearlite during continuous cooling, and to enhance the formability/forgability of the non-ferrous precipitation hardening magnesium alloy AZ90 by applying a high magnetic field during deformation processing to investigate potential magnetoplasticity in this material. Significant experimental issues (especially non-isothermal conditions evolving upon insertion of an isothermal sample in the high magnetic field) were encountered in the isothermal phase transformation reversal experiments (Task 4) that later were determined to be due to various condensed matter physics phenomenon such as the magnetocaloric (MCE) effect that occurs in the vicinity of a materials Curie temperature. Similarly the experimental deformation rig had components for monitoring deformation/strain (Task 3) that were susceptible to the high magnetic field of the ORNL Thermomagnetic Processing facility 9-T superconducting magnet that caused electronic components to fail or record erroneous (very noisy) signals. Limited experiments on developing nanocrystalline spacing pearlite were not sufficient to elucidate the impact of high magnetic field processing on the final pearlite spacing since significant statistical evaluation of many pearlite colonies would need to be done to be conclusive. Since extensive effort was devoted to resolving issues for Tasks 3 and 7, only results for these focused activities are included in this final CRADA report along with those for Task 7 (described in the Objectives Section of this report).

Ludtka, G.M.; Mackiewicz- Ludtka, G.; Wilgen, J.B.; Kisner, R.A.

2010-06-27T23:59:59.000Z

246

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

247

Magnetic Reconnection in the MST Reversed Field Pinch  

SciTech Connect (OSTI)

Magnetic field line reconnection is a process whereby magnetic field lines which are otherwise topologically preserved by, and frozen into, a plasma can break and reconnect to form field lines with different topologies. It plays a significant role in a wide variety of plasmas, including stellar, space and laboratory plasmas. The focus of this dissertation is the underlying dynamics of reconnection in one particular kind of laboratory plasma: the Reversed Field Pinch (RFP). Specifically, this dissertation reports measurements, made using a pair of insertable diagnostics in conjunction with arrays of magnetic sensing coils positioned near the plasma surface, of the spatial structure of the magnetic and parallel current density fluctuations associated with reconnection in the edge of MST. At least 4 significant results are obtained form such measurements. First we observe direct evidence of reconnection which takes the form of tearing modes in an RFP. Specifically we measure a (radial) magnetic field fluctuation that causes reconnection in the so-called reversal surface, or q = 0 surface, in the edge of MST. Notably this evidence of reconnection at the reversal surface is the first of its kind in an RFP. Second, we measure the radial width of the associated current sheet, or fluctuation in the component of the current density parallel to the equilibrium magnetic field. Such current sheets are a characteristic feature of the reconnection process but their radial widths are sensitive to the specific effects that allow reconnection to occur sometimes call non-ideal effects because reconnection is forbidden by ideal MHD. We compare the observed width to those expected from models of reconnection that incorporate different non-ideal effects in Ohm's law. In particular we see that the observed width is significantly larger than those expected form resistivity in the context of linearly unstable tearing modes and electron inertia. It is a factor of a few larger than the width expected form the electron pressure gradient effect. It is significantly smaller than the width expected from the ion inertia, but this width is not expected to be relevant to a strongly magnetized plasma such as an RFP. Notably it is comparable to the width of the magnetic island produced by the associated tearing mode. This is consistent with expectation for saturated or fully developed resistive tearing modes such as MST is believed to exhibit. It is also consistent with the broadening of a smaller width current sheet through current transport due to parallel streaming of charge carriers (along the field lines of the associated island). Third we obtain estimates of the radial charge transport or radial current density due to streaming charge of carriers along magnetic field lines that results from reconnection in the edge of MST. We find that in contradiction with the theoretical expectation for isolated tearing modes it is non-vanishing and in fact large enough to imply both the existence of another charge transport mechanism to maintain charge neutrality and a significant difference in the radial ion and electron particle fluxes due to parallel streaming of particles. Fourth we interpret the flux surface average of j and b as a J x B force density on the plasma. We observe in agreement with theory and observation for interacting tearing modes in an RFP that the radial structure of the force density during sawtooth crashes is such as to flatten the equilibrium radial gradient in toroidal velocity. We observe also that it is sufficiently large as to imply the existence of other force densities on the plasma.

Crocker, N.E.

2001-06-01T23:59:59.000Z

248

Voltage spike detection in high field superconducting accelerator magnets  

SciTech Connect (OSTI)

A measurement system for the detection of small magnetic flux changes in superconducting magnets, which are due to either mechanical motion of the conductor or flux jump, has been developed at Fermilab. These flux changes are detected as small amplitude, short duration voltage spikes, which are {approx}15mV in magnitude and lasts for {approx}30 {micro}sec. The detection system combines an analog circuit for the signal conditioning of two coil segments and a fast data acquisition system for digitizing the results, performing threshold detection, and storing the resultant data. The design of the spike detection system along with the modeling results and noise analysis will be presented. Data from tests of high field Nb{sub 3}Sn magnets at currents up to {approx}20KA will also be shown.

Orris, D.F.; Carcagno, R.; Feher, S.; Makulski, A.; Pischalnikov, Y.M.; /Fermilab

2004-12-01T23:59:59.000Z

249

Structure and Dynamics of the Sun's Open Magnetic Field  

E-Print Network [OSTI]

The solar magnetic field is the primary agent that drives solar activity and couples the Sun to the Heliosphere. Although the details of this coupling depend on the quantitative properties of the field, many important aspects of the corona - solar wind connection can be understood by considering only the general topological properties of those regions on the Sun where the field extends from the photosphere out to interplanetary space, the so-called open field regions that are usually observed as coronal holes. From the simple assumptions that underlie the standard quasi-steady corona-wind theoretical models, and that are likely to hold for the Sun, as well, we derive two conjectures on the possible structure and dynamics of coronal holes: (1) Coronal holes are unique in that every unipolar region on the photosphere can contain at most one coronal hole. (2) Coronal holes of nested polarity regions must themselves be nested. Magnetic reconnection plays the central role in enforcing these constraints on the field topology. From these conjectures we derive additional properties for the topology of open field regions, and propose several observational predictions for both the slowly varying and transient corona/solar wind.

S. K. Antiochos; C. R. DeVore; J. T. Karpen; Z. Mikic

2007-05-30T23:59:59.000Z

250

Effect of External Magnetic Fields on the Operation of RF Cavities  

SciTech Connect (OSTI)

Recent experiments have shown severe surface damage and a reduction of the maximum accelerating gradient for an rf cavity that is operating under external magnetic fields. This implies that serious problems may occur in lattices where rf cavities and external magnetic fields coexist, such as those of the proposed neutrino factory and muon collider. Although existing data suggest that this magnetic field dependent breakdown is associated with the emission of electrons from locally enhanced field regions on the cavity surface, the mechanism that drives this effect is not yet well understood. Here, we show that such field emitted electrons are accelerated by the cavity and focused by the magnetic field to the other side of the cavity where they heat its surface. We show that if the magnetic field is strong, significant surface deformation can occur that eventually could limit the accelerating gradient of the cavity. Results of our model are compared to the existing experimental data from an 805 MHz cavity. The geometry of the pillbox cavity in our case is more complicated, and the analysis depends on the electron energies, focused dimensions, and angle of impact, but damage may reasonably be expected with similar cyclical heating above 40 C. However, it is not yet known what the mechanism is for such surface damage to cause a cavity to breakdown. One possibility is that if electrons are focused on a location with a high surface gradient, then the local damage will generate new asperities with higher FN enhancement factors, thus initiating breakdown. While our preliminary analysis offers some quantification on the effects of the magnetic fields on the cavity's operation, other theoretical issues were not addressed. For instance, emission from secondary electrons was disregarded, the asperity was placed on axis, the magnetic field was assumed as uniform, the thermal-diffusion calculation ignored the shape of the rise time, and adopted an approximate calculation. On the theoretical level, it will be interesting to pursue additional simulations exploring these effects in detail. Experimentally, there is a clear need for more well-designed experiments to study, systematically, the effect of external fields on the cavity's operation.

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

2010-12-01T23:59:59.000Z

251

Transport of Magnetic Fields in Convective, Accreting Supernova Cores  

E-Print Network [OSTI]

We consider the amplification and transport of a magnetic field in the collapsed core of a massive star, including both the region between the neutrinosphere and the shock, and the central, opaque core. An analytical argument explains why rapid convective overturns persist within a newly formed neutron star for roughly 10 seconds ($> 10^3$ overturns), consistent with recent numerical models. A dynamical balance between turbulent and magnetic stresses within this convective layer corresponds to flux densities in excess of $10^{15}$G. Material accreting onto the core is heated by neutrinos and also becomes strongly convective. We compare the expected magnetic stresses in this convective `gain layer' with those deep inside the neutron core. Buoyant motions of magnetized fluid are greatly aided by the intense neutrino flux. We calculate the transport rate through a medium containing free neutrons protons, and electrons, in the limiting cases of degenerate or non-degenerate nucleons. Fields stronger than $\\sim 10^{13}$ G are able to rise through the outer degenerate layers of the neutron core during the last stages of Kelvin-Helmholtz cooling (up to 10 seconds post-collapse), even though these layers have become stable to convection. We also find the equilibrium shape of a thin magnetic flux rope in the dense hydrostatic atmosphere of the neutron star, along with the critical separation of the footpoints above which the rope undergoes unlimited expansion against gravity. The implications of these results for pulsar magnetism are summarized, and applied to the case of late fallback over the first 1,000-10,000 s of the life of a neutron star

Christopher Thompson; Norman Murray

2001-05-24T23:59:59.000Z

252

Millimeter Scale Alignment of Magnetic Nanoparticle Functionalized Microtubules in Magnetic Fields  

E-Print Network [OSTI]

, transporting cargo up to a meter in biological systems.1 Harnessing the unique properties of this motor direction of the cargo-laden motors and potentially enable the assembly of complex nanostruc- tures. To date techniques,4 by viscous forces,5 or by strong magnetic or electric fields applied during tubule

Hancock, William O.

253

Cryogenic properties of dispersion strengthened copper for high magnetic fields  

SciTech Connect (OSTI)

Cold deformed copper matrix composite conductors, developed for use in the 100 tesla multi-shot pulsed magnet at the National High Magnetic Field Laboratory (NHMFL), have been characterized. The conductors are alumina strengthened copper which is fabricated by cold drawing that introduces high dislocation densities and high internal stresses. Both alumina particles and high density of dislocations provide us with high tensile strength and fatigue endurance. The conductors also have high electrical conductivities because alumina has limited solubility in Cu and dislocations have little scattering effect on conduction electrons. Such a combination of high strength and high conductivity makes it an excellent candidate over other resistive magnet materials. Thus, characterization is carried out by tensile testing and fully reversible fatigue testing. In tensile tests, the material exceeds the design criteria parameters. In the fatigue tests, both the load and displacement were measured and used to control the amplitude of the tests to simulate the various loading conditions in the pulsed magnet which is operated at 77 K in a non-destructive mode. In order to properly simulate the pulsed magnet operation, strain-controlled tests were more suitable than load controlled tests. For the dispersion strengthened coppers, the strengthening mechanism of the aluminum oxide provided better tensile and fatigue properties over convention copper.

Toplosky, V. J.; Han, K.; Walsh, R. P. [National High Magnetic Field Laboratory, Tallahassee, FL 32310 (United States); Swenson, C. A. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2014-01-27T23:59:59.000Z

254

Charge-Transfer Induced Magnetic Field Effects of Nano-Carbon Heterojunctions  

E-Print Network [OSTI]

positive and negative polarons. Here, we demonstrate charge-transfer induced magnetic field effects in nano-carbon C60-SWCNT bulk heterojunctions at room temperature, where the mechanism of magnetic field effects is verified using excited state transition...

Qin, Wei; Gong, Maogang; Shastry, Tejas; Hersam, Mark C.; Ren, Shenqiang

2014-08-22T23:59:59.000Z

255

Magnetic field sensors using 13-spin cat states  

E-Print Network [OSTI]

Measurement devices could benefit from entangled correlations to yield a measurement sensitivity approaching the physical Heisenberg limit. Building upon previous magnetometric work using pseudo-entangled spin states in solution-state NMR, we present two conceptual advancements to better prepare and interpret the pseudo-entanglement resource as well as the use of a 13-spin cat state to measure the local magnetic field with a sensitivity beyond the standard quantum limit.

Stephanie Simmons; Jonathan A. Jones; Steven D. Karlen; Arzhang Ardavan; John J. L. Morton

2010-11-24T23:59:59.000Z

256

Circuitry, systems and methods for detecting magnetic fields  

DOE Patents [OSTI]

Circuitry for detecting magnetic fields includes a first magnetoresistive sensor and a second magnetoresistive sensor configured to form a gradiometer. The circuitry includes a digital signal processor and a first feedback loop coupled between the first magnetoresistive sensor and the digital signal processor. A second feedback loop which is discrete from the first feedback loop is coupled between the second magnetoresistive sensor and the digital signal processor.

Kotter, Dale K. (Shelley, ID) [Shelley, ID; Spencer, David F. (Idaho Falls, ID) [Idaho Falls, ID; Roybal, Lyle G. (Idaho Falls, ID) [Idaho Falls, ID; Rohrbaugh, David T. (Idaho Falls, ID) [Idaho Falls, ID

2010-09-14T23:59:59.000Z

257

Conference Summary: The Cosmic Agitator - Magnetic Fields in the Galaxy  

E-Print Network [OSTI]

We present a summary of the conference "The Cosmic Agitator: Magnetic Fields in the Galaxy" held in Lexington KY in 2008 Mar 26-29. The presentation draws primarily from material in the slides prepared for the Conference Summary by one of us (Carl Heiles). Interested readers may navigate to the conference web site given in the paper to view the posted presentations in detail.

T. H. Troland; C. Heiles; A. P. Sarma; G. J. Ferland; R. M. Crutcher; C. L. Brogan

2008-04-21T23:59:59.000Z

258

Progress In Electromagnetics Research B, Vol. 13, 120, 2009 MAGNETIC FIELD PRODUCED BY A TILE  

E-Print Network [OSTI]

by permanent magnets is very useful for optimizing alternate magnet structures or magnetic couplings PERMANENT MAGNET WHOSE POLARIZATION IS BOTH UNIFORM AND TANGENTIAL R. Ravaud, G. Lemarquand, V. Lemarquand field produced by a tile permanent magnet whose polarization is both tangential and uniform

Paris-Sud XI, Université de

259

Ballistic dynamics of Dirac particles in electro-magnetic fields  

E-Print Network [OSTI]

Investigating properties of two-dimensional Dirac operators coupled to an electric and a magnetic field (perpendicular to the plane) requires in general unbounded (vector-) potentials. If the system has a certain symmetry, the fields can be described by one-dimensional potentials $V$ and $A$. Assuming that $|A|<|V|$ outside some arbitrary large ball, we show that absolutely continuous states of the effective Dirac operators spread ballistically. These results are based on well-known methods in spectral dynamics together with certain new Hilbert-Schmidt bounds. We use Lorentz boosts to derive these new estimates.

Josef Mehringer; Edgardo Stockmeyer

2014-11-21T23:59:59.000Z

260

Interior Permanent Magnet Reluctance Machine with Brushless Field Excitation  

SciTech Connect (OSTI)

In a conventional permanent magnet (PM) machine, the air-gap flux produced by the PM is fixed. It is difficult to enhance the air-gap flux density due to limitations of the PM in a series-magnetic circuit. However, the air-gap flux density can be weakened by using power electronic field weakening to the limit of demagnetization of the PMs. This paper presents the test results of controlling the PM air-gap flux density through the use of a stationary brushless excitation coil in a reluctance interior permanent magnet with brushless field excitation (RIPM-BFE) motor. Through the use of this technology the air-gap flux density can be either enhanced or weakened. There is no concern with demagnetizing the PMs during field weakening. The leakage flux of the excitation coil through the PMs is blocked. The prototype motor built on this principle confirms the concept of flux enhancement and weakening through the use of excitation coils.

Wiles, R.H.

2005-10-07T23:59:59.000Z

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

Electric Fields and Chiral Magnetic Effect in Cu + Au Collisions  

E-Print Network [OSTI]

The non-central Cu + Au collisions can create strong out-of-plane magnetic fields and in-plane electric fields. By using the HIJING model, we study the general properties of the electromagnetic fields in Cu + Au collisions at 200 GeV and their impacts on the charge-dependent two-particle correlator $\\gamma_{q_1q_2}=$ (see main text for definition) which was used for the detection of the chiral magnetic effect (CME). Compared with Au + Au collisions, we find that the in-plane electric fields in Cu + Au collisions can strongly suppress the two-particle correlator or even reverse its sign if the lifetime of the electric fields is long. Combining with the expectation that if $\\gamma_{q_1q_2}$ is induced by elliptic-flow driven effects we would not see such strong suppression or reversion, our results suggest to use Cu + Au collisions to test CME and understand the mechanisms that underlie $\\gamma_{q_1q_2}$.

Wei-Tian Deng; Xu-Guang Huang

2015-02-16T23:59:59.000Z

262

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

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

Analytical Calculation Summary: , torque, magnetic field, PM Synchronous motors 1 INTRODUCTION IRONLESS electrical machines are generally... of iron parts whose...

263

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

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

Analytical Calculation Summary: , torque, magnetic field, PM Synchronous motors 1 INTRODUCTION IRONLESS electrical machines are generally... of iron parts whose...

264

Dynamics of multiple viscoelastic carbon nanotube based nanocomposites with axial magnetic field  

SciTech Connect (OSTI)

Nanocomposites and magnetic field effects on nanostructures have received great attention in recent years. A large amount of research work was focused on developing the proper theoretical framework for describing many physical effects appearing in structures on nanoscale level. Great step in this direction was successful application of nonlocal continuum field theory of Eringen. In the present paper, the free transverse vibration analysis is carried out for the system composed of multiple single walled carbon nanotubes (MSWCNT) embedded in a polymer matrix and under the influence of an axial magnetic field. Equivalent nonlocal model of MSWCNT is adopted as viscoelastically coupled multi-nanobeam system (MNBS) under the influence of longitudinal magnetic field. Governing equations of motion are derived using the Newton second low and nonlocal Rayleigh beam theory, which take into account small-scale effects, the effect of nanobeam angular acceleration, internal damping and Maxwell relation. Explicit expressions for complex natural frequency are derived based on the method of separation of variables and trigonometric method for the “Clamped-Chain” system. In addition, an analytical method is proposed in order to obtain asymptotic damped natural frequency and the critical damping ratio, which are independent of boundary conditions and a number of nanobeams in MNBS. The validity of obtained results is confirmed by comparing the results obtained for complex frequencies via trigonometric method with the results obtained by using numerical methods. The influence of the longitudinal magnetic field on the free vibration response of viscoelastically coupled MNBS is discussed in detail. In addition, numerical results are presented to point out the effects of the nonlocal parameter, internal damping, and parameters of viscoelastic medium on complex natural frequencies of the system. The results demonstrate the efficiency of the suggested methodology to find the closed form solutions for the free vibration response of multiple nanostructure systems under the influence of magnetic field.

Karli?i?, Danilo; Caji?, Milan [Mathematical Institute of the SASA, Kneza Mihaila 36, Belgrade 11001 (Serbia); Murmu, Tony [School of Engineering, University of the West of Scotland, Paisley PA12BE (United Kingdom); Kozi?, Predrag [Faculty of Mechanical Engineering, University of Niš, A. Medvedeva 14, 18000 Niš (Serbia); Adhikari, Sondipon [College of Engineering, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom)

2014-06-21T23:59:59.000Z

265

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

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

Science 70 nature materials | VOL 6 | JANUARY 2007 | www.nature.comnaturematerials 13 REVIEW ARTICLE Summary: governing the dynamics of electric fields, magnetic fields and...

266

The influence of a magnetic field on turbulent heat transfer of a high Prandtl number fluid  

SciTech Connect (OSTI)

The influence of a transverse magnetic field on the local and average heat transfer of an electrically conducting, turbulent fluid flow with high Prandtl number was studied experimentally. The mechanism of heat transfer modification due to magnetic field is considered with aid of available numerical simulation data for turbulent flow field. The influence of the transverse magnetic field on the heat transfer was to suppress the temperature fluctuation and to steepen the mean temperature gradient in near-wall region in the direction parallel to the magnetic field. The mean temperature gradient is not influenced compared to the temperature fluctuation in the direction vertical to the magnetic field. (author)

Nakaharai, H. [Department of Advanced Energy Engineering Science, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga-kouen 6-1, Kasuga, Fukuoka 816-8580 (Japan); Takeuchi, J.; Morley, N.B.; Abdou, M.A. [Mechanical and Aerospace Engineering Department, University of California, Los Angeles, CA 90095-1597 (United States); Yokomine, T. [Faculty of Energy Engineering Science, Kyushu University, Kasuga-kouen 6-1, Kasuga, Fukuoka 816-8580 (Japan); Kunugi, T. [Department of Nuclear Engineering, Kyoto University, Yoshida, Sakyo, Kyoto 606-8501 (Japan); Satake, S. [Department of Applied Electronics, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan)

2007-10-15T23:59:59.000Z

267

Compressing magnetic fields with high-energy lasersa... J. P. Knauer,1,b  

E-Print Network [OSTI]

Compressing magnetic fields with high-energy lasersa... J. P. Knauer,1,b O. V. Gotchev,1,2,3 P. Y, Rochester, New York 14623, USA 3 Department of Mechanical Engineering, University of Rochester, 250 East-driven magnetic-field compression producing a magnetic field of tens of megaGauss is reported for the first time

268

The chaotic oscillations of a Josephson junction with external magnetic field  

SciTech Connect (OSTI)

Using the Melnikov Method the oscillation of a single Josephson junction with external magnetic field and DC bias is analyzed. Under the external magnetic field the junction can operate in chaos even if there is no bias. The numerical results show that in dependence on some parameters the Josephson junction with external magnetic field will go from stable periodic states to chaotic states.

Ma, J.G.; Wolff, I. [Duisburg Univ. (Germany). Dept. of Electrical Engineering

1996-05-01T23:59:59.000Z

269

Stellar coronal magnetic fields and star-planet interaction  

E-Print Network [OSTI]

Evidence of magnetic interaction between late-type stars and close-in giant planets is provided by the observations of stellar hot spots rotating synchronously with the planets and showing an enhancement of chromospheric and X-ray fluxes. We investigate star-planet interaction in the framework of a magnetic field model of a stellar corona, considering the interaction between the coronal field and that of a planetary magnetosphere moving through the corona. The energy budget of the star-planet interaction is discussed assuming that the planet may trigger a release of the energy of the coronal field by decreasing its relative helicity. The observed intermittent character of the star-planet interaction is explained by a topological change of the stellar coronal field, induced by a variation of its relative helicity. The model predicts the formation of many prominence-like structures in the case of highly active stars owing to the accumulation of matter evaporated from the planet inside an azimuthal flux rope in ...

Lanza, A F

2009-01-01T23:59:59.000Z

270

High-precision description and new properties of a spin-1 particle in a magnetic field  

E-Print Network [OSTI]

The exact Foldy-Wouthuysen Hamiltonian is derived for a pointlike spin-1 particle with a normal magnetic moment in a nonuniform magnetic field. For a uniform magnetic field, it is exactly separated into terms linear and quadratic in spin. New unexpected properties of a particle with an anomalous magnetic moment are found. Spin projections of a particle moving in a uniform magnetic field are not integer and the tensor polarization is asymmetric in the plane orthogonal to the field. Previously described spin-tensor effects caused by the tensor magnetic polarizability exist not only for nuclei but also for pointlike particles.

Alexander J. Silenko

2014-06-09T23:59:59.000Z

271

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

E-Print Network [OSTI]

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

Zach Medin; Dong Lai

2007-01-05T23:59:59.000Z

272

Transmit field pattern control for high field magnetic resonance imaging with integrated RF current sources  

E-Print Network [OSTI]

in units of radians/tesla and B is the magnetic flux density of the applied field, expressed in units of tesla. The hydrogen nucleus, which consists of a single proton, is the most abundantly present in tissue and is most widely used for MRI...

Kurpad, Krishna Nagaraj

2005-11-01T23:59:59.000Z

273

Effect of primordial magnetic fields on the ionization history  

E-Print Network [OSTI]

Primordial magnetic fields (PMF) damp at scales smaller than the photon diffusion and free-streaming scale. This leads to heating of ordinary matter (electrons and baryons), which affects both the thermal and ionization history of our Universe. Here, we study the effect of heating due to ambipolar diffusion and decaying magnetic turbulence. We find that changes to the ionization history computed with recfast are significantly overestimated when compared with CosmoRec. The main physical reason for the difference is that the photoionization coefficient has to be evaluated using the radiation temperature rather than the matter temperature. A good agreement with CosmoRec is found after changing this aspect. Using Planck 2013 data and considering only the effect of PMF-induced heating, we find an upper limit on the r.m.s. magnetic field amplitude of B0 < 1.1 nG (95% c.l.) for a stochastic background of PMF with a nearly scale-invariant power spectrum. We also discuss uncertainties related to the approximations ...

Chluba, Jens; Finelli, Fabio; Rubino-Martin, Jose-Alberto

2015-01-01T23:59:59.000Z

274

Strong magnetic fields and inhomogeneity in the solar corona  

SciTech Connect (OSTI)

It is shown that fields of 1800 G can exist in the corona based on observations of gyroresonance emission at 15 GHz at coronal temperatures. The strong fields occur in a small source radiating in the extraordinary (x) mode over the penumbra of a large symmetric sunspot. The optically-thin ordinary mode emission from the region shows a nearby peak at only 36,000 K which may be due to a sunspot plume, and a hole over the umbra consistent with the expected low-density material there. The x-mode source is highly asymmetric, despite the apparent symmetry of the sunspot, and its appearance and location imply that the strongest magnetic fields in the corona are localized in a compact flux tube. 21 refs.

White, S.M.; Kundu, M.R.; Gopalswamy, N. (Maryland Univ., College Park (USA))

1991-01-01T23:59:59.000Z

275

Collective Modes of Chiral Kinetic Theory in Magnetic Field  

E-Print Network [OSTI]

We study collective excitations in systems described by chiral kinetic theory in external magnetic field. We consider high-temperature weak-coupling plasma, as well as high-density Landau Fermi liquid with interaction not restricted to be weak. We show that chiral magnetic wave (CMW) emerges in hydrodynamic regime (at frequencies smaller than collision relaxation rate) and the CMW velocity is determined by thermodynamic properties only. We find that in a plasma of opposite chiralities, at frequencies smaller than the chirality-flipping rate, the CMW excitation turns into a vector-like diffusion mode. In the interacting Fermi liquid, the CMW turns into the Landau zero sound mode in the high-frequency collisionless regime.

Mikhail Stephanov; Ho-Ung Yee; Yi Yin

2014-12-31T23:59:59.000Z

276

Collective Modes of Chiral Kinetic Theory in Magnetic Field  

E-Print Network [OSTI]

We study collective excitations in systems described by chiral kinetic theory in external magnetic field. We consider high-temperature weak-coupling plasma, as well as high-density Landau Fermi liquid with interaction not restricted to be weak. We show that chiral magnetic wave (CMW) emerges in hydrodynamic regime (at frequencies smaller than collision relaxation rate) and the CMW velocity is determined by thermodynamic properties only. We find that in a plasma of opposite chiralities, at frequencies smaller than the chirality-flipping rate, the CMW excitation turns into a vector-like diffusion mode. In the interacting Fermi liquid, the CMW turns into the Landau zero sound mode in the high-frequency collisionless regime.

Stephanov, Mikhail; Yin, Yi

2015-01-01T23:59:59.000Z

277

Weak magnetic field effects on chiral critical temperature in a nonlocal Nambu--Jona-Lasinio model  

E-Print Network [OSTI]

In this article we study the nonlocal Nambu--Jona-Lasinio model with a Gaussian regulator in the chiral limit. Finite temperature effects and the presence of a homogeneous magnetic field are considered. The magnetic evolution of the critical temperature for chiral symmetry restoration is then obtained. Here we restrict ourselves to the case of low magnetic field values, being this a complementary discussion to the exisiting analysis in nonlocal models in the strong magnetic field regime.

M. Loewe; F. Marquez; C. Villavicencio; R. Zamora

2014-10-27T23:59:59.000Z

278

Thermal and high magnetic field treatment of materials and associated apparatus  

DOE Patents [OSTI]

An apparatus and method for altering characteristics, such as can include structural, magnetic, electrical, optical or acoustical characteristics, of an electrically-conductive workpiece utilizes a magnetic field within which the workpiece is positionable and schemes for thermally treating the workpiece by heating or cooling techniques in conjunction with the generated magnetic field so that the characteristics of the workpiece are effected by both the generated magnetic field and the thermal treatment of the workpiece.

Kisner, Roger A.; Wilgen, John B.; Ludtka, Gerard M.; Jaramillo, Roger A.; Mackiewicz-Ludtka, Gail

2010-06-29T23:59:59.000Z

279

Thermal and high magnetic field treatment of materials and associated apparatus  

DOE Patents [OSTI]

An apparatus and method for altering characteristics, such as can include structural, magnetic, electrical, optical or acoustical characteristics, of an electrically-conductive workpiece utilizes a magnetic field within which the workpiece is positionable and schemes for thermally treating the workpiece by heating or cooling techniques in conjunction with the generated magnetic field so that the characteristics of the workpiece are effected by both the generated magnetic field and the thermal treatment of the workpiece.

Kisner, Roger A.; Wilgen, John B.; Ludtka, Gerard M.; Jaramillo, Roger A.; Mackiewicz-Ludtka, Gail

2007-01-09T23:59:59.000Z

280

National High Magnetic Field Laboratory - Series Connected Hybrid  

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

Magnet Lab Series Connected Hybrid for Magnet Lab Figure 1. Vertical Section of the Series Connected Hybrid Magnet for the Mag Lab. The Magnet Lab has embarked on innovative...

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

Perfect 2-d quadrupole fields from permanent magnets  

SciTech Connect (OSTI)

Consider the 13-beam channel array shown in Figure 1. It is asserted that, under mathematically ideal assumptions, a pure quadrupole field is centered in each of the 13 beam channel boxes. An identical quadrupole field (for {bar H}, not {bar B}) is also centered in each of the 4 boxes containing 4 magnetic wedges located near the center of the system. An iron yoke ({mu} = {infinity}) with the displayed zig-zag shape provides a boundary condition (H{sub {parallel}} = 0) that makes the 13 channels equivalent to a portion of an infinite array. A similar array can be readily drawn for any number of beams. The quadrupole gradient in the beam channels is B{prime} = M{sub o}/2b, where M{sub o} is the remnant field of the magnetic wedges, and the channel diameter (wedge-to-wedge) is 2b. Note that a unit cell of the array, containing one beam, has diameter 2{radical}2 b (viewed from 45{degree} tilt) so its area is 8 b{sup 2}. A significant advantage of this design over those using dipolar blocks is the large fraction of cross section devoted to beam channels (50% vs 25%). Application to a heavy ion fusion driver is discussed.

Lee, E.P.; Vella, M. [Lawrence Berkeley National Lab., CA (United States). Accelerator and Fusion Research Div.

1996-04-01T23:59:59.000Z

282

BTA Magnet Field Map Archive and MAD Model  

SciTech Connect (OSTI)

This note publishes some and information that has resided in private files. The attached tables were provided by Joseph Skelly from his archives. They show magnetic field measurements versus excitation current for the Booster to AGS transfer line quadrupoles and dipoles based on field measurements [we believe] were done by the Magnet Division. Also given are Ed Blesser's fifth order fits of field versus current. The results are given in 'Tesla' or T-M/M. These tables are attached to provide an archive of this data. The MAD model of the BTA line does have the same values as shown in the attached fits so the transfer was correct. MAD uses as its 'gradient' for quads Tesla per meter normalized to rigidity [B-rho]. The model of the BTA line in use uses the T-M/M given in the tables divided by the length to give T M which is then normalized by Brho. Thus, the input to the model appears to be correct. The original model is also attached as part of a memo by Skelly describing it.

Glenn,J.W.

2008-04-01T23:59:59.000Z

283

Influence of spatially varying pseudo-magnetic field on a 2D electron gas in graphene  

E-Print Network [OSTI]

The effect of a varying pseudo-magnetic field, which falls as $1/x^2$, on a two dimensional electron gas in graphene is investigated. By considering the second order Dirac equation, we show that its correct general solution is that which might present singular wavefunctions since such field induced by elastic deformations diverges as $x\\rightarrow0$. We show that only this consideration yields the known relativistic Landau levels when we remove such elastic field. We have observed that the zero Landau level fails to develop for certain values of it. We then speculate about the consequences of these facts to the quantum Hall effect on graphene. We also analyze the changes in the relativistic cyclotron frequency. We hope our work being probed in these contexts, since graphene has great potential for electronic applications.

L. G. da Silva Leite; D. Cogollo; C. Filgueiras; Edilberto O. Silva

2015-01-28T23:59:59.000Z

284

Interaction of biological systems with static and ELF electric and magnetic fields  

SciTech Connect (OSTI)

Although background levels of atmospheric electric and geomagnetic field levels are extremely low, over the past several decades, human beings and other life forms on this planet have been subjected to a dramatically changing electromagnetic milieu. An exponential increase in exposure to electromagnetic fields has occurred, largely because of such technological advances as the growth of electrical power generation and transmission systems, the increased use of wireless communications, and the use of radar. In addition, electromagnetic field generating devices have proliferated in industrial plants, office buildings, homes, public transportation systems, and elsewhere. Although significant increases have occurred in electromagnetic field strenghths spanning all frequency ranges, this symposium addresses only the impact of these fields at static and extremely low frequencies (ELF), primarily 50 and 60 Hz. This volume contains the proceedings of the symposium entitled /open quotes/Interaction of biological systems with static and ELF electric and magnetic fields/close quotes/. The purpose of the symposium was to provide a forum for discussions of all aspects of research on the interaction of static and ELF electromagnetic fields with biological systems. These systems include simple biophysical models, cell and organ preparations, whole animals, and man. Dosimetry, exposure system design, and artifacts in ELF bioeffects research were also addressed, along with current investigations that examine fundamental mechanisms of interactions between the fields and biological processes. Papers are indexed separately.

Anderson, L.E.; Kelman, B.J.; Weigel, R.J. (eds.)

1987-01-01T23:59:59.000Z

285

System having unmodulated flux locked loop for measuring magnetic fields  

DOE Patents [OSTI]

A system (10) for measuring magnetic fields, wherein the system (10) comprises an unmodulated or direct-feedback flux locked loop (12) connected by first and second unbalanced RF coaxial transmission lines (16a, 16b) to a superconducting quantum interference device (14). The FLL (12) operates for the most part in a room-temperature or non-cryogenic environment, while the SQUID (14) operates in a cryogenic environment, with the first and second lines (16a, 16b) extending between these two operating environments.

Ganther, Jr., Kenneth R. (Olathe, KS); Snapp, Lowell D. (Blue Springs, MO)

2006-08-15T23:59:59.000Z

286

NATIONAL HIGH MAGNETIC FIELD LABORATORY REPORTSVOLUME 11 N0.1 2004  

E-Print Network [OSTI]

NATIONAL HIGH MAGNETIC FIELD LABORATORY REPORTSVOLUME 11 · N0.1 · 2004 OPERATED BY: FLORIDA STATE R E V I E W BIOLOGY BIOCHEMISTRY CHEMISTRY CRYOGENICS ENGINEERING MATERIALS GEOCHEMISTRY INSTRUMENTATION KONDO/HEAVY FERMION SYSTEMS MAGNET TECHNOLOGY MAGNETIC RESONANCE TECHNIQUES MAGNETISMAND MAGNETIC

Weston, Ken

287

Phase-field simulation of strain-induced domain switching in magnetic thin films  

E-Print Network [OSTI]

Phase-field simulation of strain-induced domain switching in magnetic thin films Jia-Mian Hu, G of the Bloch point in a magnetic film with strong uniaxial magnetic anisotropy Low Temp. Phys. 37, 690 (2011) Evolution of magnetic bubble domains in manganite films Appl. Phys. Lett. 99, 042503 (2011) 360° domain wall

Chen, Long-Qing

288

Thermoelectric Conductivities at Finite Magnetic Field and the Nernst Effect  

E-Print Network [OSTI]

We study electric, thermoelectric, and thermal conductivities of a strongly correlated system in the presence of magnetic field by gauge/gravity duality. We consider a general class of Einstein-Maxwell-Dilaton theory with axion fields imposing momentum relaxation. Analytic general formulas for DC conductivities and the Nernst signal are derived in terms of the black hole horizon data. For an explicit model study we analyse in detail the dyonic black hole modified by momentum relaxation. In this model, the Nernst signal shows a typical vortex-liquid effect when momentum relaxation effect is comparable to chemical potential. We compute all AC electric, thermoelectric, and thermal conductivities by numerical analysis and confirms that their zero frequency limits precisely reproduce our analytic formulas, which is a non-trivial consistency check of our methods. We discuss the momentum relaxation effect on conductivities including cyclotron resonance poles.

Keun-Young Kim; Kyung Kiu Kim; Yunseok Seo; Sang-Jin Sin

2015-03-17T23:59:59.000Z

289

Ferrofluid nucleus phase transitions in an external uniform magnetic field  

E-Print Network [OSTI]

Phase transition between massive dense phase and diluted superparamagnetic phase is studied by means of direct molecular dynamics simulation. Equilibrium structures of ferrofluid aggregate nucleus are obtained for different values of temperature and external magnetic field magnitude. For the ferrofluid phase diagram (coordinates "field-temperature"): approximate match of experiment and simulation is shown. Obtained phase coexistence curve has opposite trend compare to some of known theoretical results. This contradiction is related to postulating and comparing of the free energy of only simplest ferrofluid structures: diluted superparamagnetic phase, linear chains of the particles, and dense globes. The present results provide more fine structure of transition from "linear chains" to "dense globes" phase, e.g. through the ring assembly structure.

B. M. Tanygin; S. I. Shulyma; V. F. Kovalenko; M. V. Petrychuk

2015-02-18T23:59:59.000Z

290

Inelastic neutron scttering study o fcrystal field levels in PrOs4As12  

SciTech Connect (OSTI)

We use neutron scattering to study the Pr$^{3+}$ crystalline electric field (CEF) excitations in the filled skutterudite PrOs$_4$As$_{12}$. By comparing the observed levels and their strengths under neutron excitation with the theoretical spectrum and neutron excitation intensities, we identify the Pr$^{3+}$ CEF levels, and show that the ground state is a magnetic $\\Gamma_4^{(2)}$ triplet, and the excited states $\\Gamma_1$, $\\Gamma_4^{(1)}$ and $\\Gamma_{23}$ are at 0.4, 13 and 23~meV, respectively. A comparison of the observed CEF levels in PrOs$_4$As$_{12}$ with the heavy fermion superconductor PrOs$_4$Sb$_{12}$ reveals the microscopic origin of the differences in the ground states of these two filled skutterudites.

Chi, Songxue [ORNL; Dai, Pengcheng [ORNL; Barnes, Ted {F E } [ORNL; Kang, H. J. [National Institute of Standards and Technology (NIST); Lynn, J. W. [National Institute of Standards and Technology (NIST); Ye, Feng [ORNL; Maple, M. B. [University of California, San Diego

2008-01-01T23:59:59.000Z

291

Atom interferometric techniques for measuring gravitational acceleration and constant magnetic field gradients  

E-Print Network [OSTI]

We discuss two techniques for probing the effects of a homogeneous force acting on cold atoms, such as that due to gravity or a constant magnetic field gradient, using grating echo-type atom interferometers. A comprehensive theoretical description of signals generated by both two-pulse and three-pulse interferometers, accounting for magnetic sub-levels in the atomic ground state, is shown to agree with experimental results. Laser-cooled samples of $^{85}$Rb with temperatures as low as 2.4 $\\mu$K have been achieved in a relatively large glass cell with well-suppressed magnetic fields. Using transit time limited interferometer signals, we demonstrate sensitivity to externally applied magnetic gradients as small as $\\sim 4$ mG/cm. With these timescales we estimate that precision measurements of the gravitational acceleration, $g$, are possible with both the two-pulse and three-pulse echo interferometers. Whereas the two-pulse signal is a position-sensitive technique to measure the absolute value of $g$, the thre...

Barrett, B

2011-01-01T23:59:59.000Z

292

Multilayer film shields for the protection of PMT from constant magnetic field  

E-Print Network [OSTI]

Photomultiplier tubes (PMTs) are widely used in physical experiments as well as in applied devices. PMTs are sensitive to magnetic field, so creation of effective magnetic shields for their protection is very important. In this paper, the results...

Dmitrenko, V. V.; Besson, David; Nyunt, PhyoWai; Grabchikov, S. S.; Grachev, V. M.; Muraviev-Smirnov, C. C.; Ulin, S. E.; Utechev, Z. M.; Vlasik, K. F.

2015-01-13T23:59:59.000Z

293

Magnetic resonance studies of cement based materials in inhomogeneous magnetic fields  

SciTech Connect (OSTI)

Single-sided magnets give hope that Nuclear Magnetic Resonance (NMR) might in future be used for in situ characterisation of hydration and water transport in the surface layers of concrete slabs. Towards that end, a portable NMR-MOUSE (MObile Universal Surface Explorer) has been used to follow the hydration of gypsum based plaster, a Portland cement paste and concrete mortar. The results compare favourably to those obtained using a standard laboratory bench-top spectrometer. Further, stray field imaging (STRAFI) based methods have been used with embedded NMR detector coils to study water transport across a mortar/topping interface. The measured signal amplitudes are found to correlate with varying sample conditions.

Boguszynska, Joanna [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, Poznan (Poland); Brown, Marc C.A. [School of Physical Sciences, University of Kent, Canterbury, Kent, CT2 7NR (United Kingdom); McDonald, Peter J. [School of Electronics and Physical Sciences, University of Surrey, Surrey, GU2 7XH (United Kingdom)]. E-mail: p.mcdonald@surrey.ac.uk; Mitchell, Jonathan [School of Electronics and Physical Sciences, University of Surrey, Surrey, GU2 7XH (United Kingdom); Mulheron, Mike [School of Engineering, University of Surrey, Surrey, GU2 7XH (United Kingdom); Tritt-Goc, Jadwiga [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, Poznan (Poland); Verganelakis, Dimitris A. [Department of Chemical Engineering, University of Cambridge, Cambridge, CB2 3RA (United Kingdom)

2005-10-01T23:59:59.000Z

294

Memorandum, Approval of a Permanent Variance Regarding Static Magnetic Fields at Brookhaven National Laboratory (Variance 102 1)  

Broader source: Energy.gov [DOE]

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

295

High Field Magnetization measurements of uranium dioxide single crystals (P08358- E003-PF)  

SciTech Connect (OSTI)

Conclusions: Our preliminary high field magnetic measurements of UO2 are consistent with a complex nature of the magnetic ordering in this material, compatible with the previously proposed non-collinear 3-k magnetic structure. Further extensive magnetic studies on well-oriented (<100 > and <111>) UO2 crystals are planned to address the puzzling behavior of UO2 in both antiferromagnetic and paramagnetic states at high fields.

K. Gofryk; N. Harrison; M. Jaime

2014-12-01T23:59:59.000Z

296

National High Magnetic Field Laboratory Press Release: October...  

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

tested a groundbreaking new magnet design that could literally shed new light on nanoscience and semiconductor research. Split Florida Helix magnet Model of the Split Florida...

297

2011 Annual Report, National High Magnetic Field Laboratory  

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

1 The Year in Review 06 Chapter 2 Research Highlights 10 Condensed Matter Science 12 Graphene, Kondoheavy fermion systems, magnetism & magnetic materials, molecular conductors,...

298

National High Magnetic Field Laboratory - Policies and Procedures  

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

Lab Policies & Procedures Arrow Magnet Lab Policies and Procedures Numerous policies and procedures are in place at the Magnet Lab. Follow these links to learn more about them:...

299

Collisionless magnetic reconnection in the presence of a sheared velocity field  

SciTech Connect (OSTI)

The linear theory of magnetic field lines reconnection in a two-dimensional configuration in the presence of a (Kelvin-Helmholtz stable) sheared velocity field is investigated within a single fluid model, where the onset of magnetic field line reconnection is made possible by the effect of electron inertia in the so called large DELTA{sup '} regime.

Faganello, M. [Ecole Polytechnique, LPP, Palaiseau, 91128 (France); Pegoraro, F.; Califano, F. [Department of Physics, University of Pisa and CNISM, Pisa, 56127 (Italy); Marradi, L. [Department of Physics, University of Pisa and CNISM, Pisa, 56127 (Italy)] [Universite de Nice Sophia Antipolis, CNRS, Observatoire de la Cote d'Azur, 06304 Nice (France)

2010-06-15T23:59:59.000Z

300

3D MHD Free Surface Fluid Flow Simulation Based on Magnetic-Field Induction Equations  

E-Print Network [OSTI]

1 3D MHD Free Surface Fluid Flow Simulation Based on Magnetic-Field Induction Equations H.L. HUANG Huang@fusion.ucla.edu Abstract: The purpose of this paper is to present our recent efforts on 3D MHD-plane magnetic field configurations have shown that 3D MHD effects from a surface normal field gradient cause

California at Los Angeles, University of

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

Gravitational waves interacting with a spinning charged particle in the presence of a uniform magnetic field  

E-Print Network [OSTI]

The equations which determine the response of a spinning charged particle moving in a uniform magnetic field to an incident gravitational wave are derived in the linearized approximation to general relativity. We verify that 1) the components of the 4-momentum, 4-velocity and the components of the spinning tensor, both electric and magnetic moments, exhibit resonances and 2) the co-existence of the uniform magnetic field and the GW are responsible for the resonances appearing in our equations. In the absence of the GW, the magnetic field and the components of the spin tensor decouple and the magnetic resonances disappear.

D. B. Papadopoulos

2003-12-23T23:59:59.000Z

302

Hazard surveillance for workplace magnetic fields. 1: Walkaround sampling method for measuring ambient field magnitude; 2: Field characteristics from waveform measurements  

SciTech Connect (OSTI)

Recent epidemiologic research has suggested that exposure to extremely low frequency (ELF) magnetic fields (MF) may be associated with leukemia, brain cancer, spontaneous abortions, and Alzheimer`s disease. A walkaround sampling method for measuring ambient ELF-MF levels was developed for use in conducting occupational hazard surveillance. This survey was designed to determine the range of MF levels at different industrial facilities so they could be categorized by MF levels and identified for possible subsequent personal exposure assessments. Industries were selected based on their annual electric power consumption in accordance with the hypothesis that large power consumers would have higher ambient MFs when compared with lower power consumers. Sixty-two facilities within thirteen 2-digit Standard Industrial Classifications (SIC) were selected based on their willingness to participate. A traditional industrial hygiene walkaround survey was conducted to identify MF sources, with a special emphasis on work stations.

Methner, M.M.; Bowman, J.D.

1998-03-01T23:59:59.000Z

303

Measurements of magnetic fields over the pulsation cycle in six roAp stars with FORS1 at the VLT  

E-Print Network [OSTI]

With FORS1 at the VLT we have tried for the first time to measure the magnetic field variation over the pulsation cycle in six roAp stars to begin the study of how the magnetic field and pulsation interact. For the star HD101065, which has one of the highest photometric pulsation amplitudes of any roAp star, we found a signal at the known photometric pulsation frequency at the 3 sigma level in one data set; however this could not be confirmed by later observations. A preliminary simple calculation of the expected magnetic variations over the pulsation cycle suggests that they are of the same order as our current noise levels, leading us to expect that further observations with increased S/N have a good chance of achieving an unequivocal detection.

S. Hubrig; D. W. Kurtz; S. Bagnulo; T. Szeifert; M. Schoeller; G. Mathys; W. A. Dziembowski

2003-09-21T23:59:59.000Z

304

Apparatus and method for generating a magnetic field by rotation of a charge holding object  

DOE Patents [OSTI]

A device and a method for the production of a magnetic field using a Charge Holding Object that is mechanically rotated. In a preferred embodiment, a Charge Holding Object surrounding a sample rotates and subjects the sample to one or more magnetic fields. The one or more magnetic fields are used by NMR Electronics connected to an NMR Conductor positioned within the Charge Holding Object to perform NMR analysis of the sample.

Gerald, II, Rex E. (Brookfield, IL); Vukovic, Lela (Westchester, IL); Rathke, Jerome W. (Homer Glenn, IL)

2009-10-13T23:59:59.000Z

305

CHARGED TORI IN SPHERICAL GRAVITATIONAL AND DIPOLAR MAGNETIC FIELDS  

SciTech Connect (OSTI)

A Newtonian model of non-conductive, charged, perfect fluid tori orbiting in combined spherical gravitational and dipolar magnetic fields is presented and stationary, axisymmetric toroidal structures are analyzed. Matter in such tori exhibits a purely circulatory motion and the resulting convection carries charges into permanent rotation around the symmetry axis. As a main result, we demonstrate the possible existence of off-equatorial charged tori and equatorial tori with cusps that also enable outflows of matter from the torus in the Newtonian regime. These phenomena qualitatively represent a new consequence of the interplay between gravity and electromagnetism. From an astrophysical point of view, our investigation can provide insight into processes that determine the vertical structure of dusty tori surrounding accretion disks.

Slany, P.; Kovar, J.; Stuchlik, Z. [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava Bezrucovo nam. 13, CZ-746 01 Opava (Czech Republic)] [Institute of Physics, Faculty of Philosophy and Science, Silesian University in Opava Bezrucovo nam. 13, CZ-746 01 Opava (Czech Republic); Karas, V., E-mail: petr.slany@fpf.slu.cz [Astronomical Institute, Academy of Sciences, Bocni II, Prague CZ-141 31 (Czech Republic)

2013-03-01T23:59:59.000Z

306

Role of magnetic field tangency points in ICRF sheath interactions  

SciTech Connect (OSTI)

ICRF waves can sometimes interact with plasma-facing surfaces in tokamak fusion experiments causing degradation of core heating efficiency, impurity injection and even component damage. While presently available low dimensionality rf sheath models are useful in understanding many features of these interactions, more quantitative modeling will require attention to realistic geometrical details of the boundary plasma and surfaces. In this paper, we explore the situation in which there exists a tangency point of the background magnetic field with a surface. We find that the rf interactions are strongly influenced by the generation and propagation of sheath-plasma waves (SPW) along the surface. It is found that these waves preferentially propagate towards, and accumulate at, a convex tangency point. An analytical theory of SPW propagation is developed to understand these features.

Myra, J. R.; D'Ippolito, D. A. [Lodestar Research Corporation, Boulder, CO 80301 (United States); Kohno, H. [Department of Mechanical Information Science and Technology, Kyushu Institute of Technology, Fukuoka 820-8502 (Japan)

2014-02-12T23:59:59.000Z

307

Path Integral Confined Dirac Fermions in a Constant Magnetic Field  

E-Print Network [OSTI]

We consider Dirac fermion confined in harmonic potential and submitted to a constant magnetic field. The corresponding solutions of the energy spectrum are obtained by using the path integral techniques. For this, we begin by establishing a symmetric global projection, which provides a symmetric form for the Green function. Based on this, we show that it is possible to end up with the propagator of the harmonic oscillator for one charged particle. After some transformations, we derive the normalized wave functions and the eigenvalues in terms of different physical parameters and quantum numbers. By interchanging quantum numbers, we show that our solutions possed interesting properties. The density of current and the non-relativistic limit are analyzed where different conclusions are obtained.

Abdeldjalil Merdaci; Ahmed Jellal; Lyazid Chetouani

2014-04-17T23:59:59.000Z

308

Generalized Pearson distributions for charged particles interacting with an electric and/or a magnetic field  

E-Print Network [OSTI]

The linear Boltzmann equation for elastic and/or inelastic scattering is applied to derive the distribution function of a spatially homogeneous system of charged particles spreading in a host medium of two-level atoms and subjected to external electric and/or magnetic fields. We construct a Fokker-Planck approximation to the kinetic equations and derive the most general class of distributions for the given problem by discussing in detail some physically meaningful cases. The equivalence with the transport theory of electrons in a phonon background is also discussed.

A. Rossani; A. M. Scarfone

2009-03-05T23:59:59.000Z

309

Field dependences of magnetization and specific-heat coefficient in a nearly magnetic system: Liquid /sup 3/He and strong Pauli paramagnets  

SciTech Connect (OSTI)

We analytically derive the first-order magnetic-field dependences of the magnetization M and of the coefficient ..gamma.. of the specific heat, in a nearly magnetic paramagnet, at low temperature.

Beal-Monod, M.T.; Daniel, E.

1983-04-01T23:59:59.000Z

310

Ion Source for Neutral beam injection meant for plasma and magnetic field diagnostics  

E-Print Network [OSTI]

Meant for Plasma and Magnetic Field Diagnostics a Jaakkodiagnostic neutral beam injection system for measuring plasmaplasma 5 . High proton fraction and small divergence are essential for diagnostic

Kwan, Joe W.

2008-01-01T23:59:59.000Z

311

Spectroscopic Determination of the Magnetic Fields in Exploding Wire and X-pinch Plasmas  

SciTech Connect (OSTI)

In this report, we summarize the progress that was made toward developing a new magnetic field diagnostic known as Zeeman Broadening for current carrying high energy density plasmas.

Hammer, David A.

2013-12-19T23:59:59.000Z

312

Formation of current filaments and magnetic field generation in a quantum current-carrying plasma  

SciTech Connect (OSTI)

The nonlinear dynamics of filamentation instability and magnetic field in a current-carrying plasma is investigated in the presence of quantum effects using the quantum hydrodynamic model. A new nonlinear partial differential equation is obtained for the spatiotemporal evolution of the magnetic field in the diffusion regime. This equation is solved by applying the Adomian decomposition method, and then the profiles of magnetic field and electron density are plotted. It is shown that the saturation time of filamentation instability increases and, consequently, the instability growth rate and the magnetic field amplitude decrease in the presence of quantum effects.

Niknam, A. R. [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of)] [Laser and Plasma Research Institute, Shahid Beheshti University, G.C., Tehran (Iran, Islamic Republic of); Taghadosi, M. R.; Majedi, S.; Khorashadizadeh, S. M. [Physics Department, University of Birjand, Birjand (Iran, Islamic Republic of)] [Physics Department, University of Birjand, Birjand (Iran, Islamic Republic of)

2013-09-15T23:59:59.000Z

313

Dispersion relation and growth rate in a Cherenkov free electron laser: Finite axial magnetic field  

SciTech Connect (OSTI)

A theoretical analysis is presented for dispersion relation and growth rate in a Cherenkov free electron laser with finite axial magnetic field. It is shown that the growth rate and the resonance frequency of Cherenkov free electron laser increase with increasing axial magnetic field for low axial magnetic fields, while for high axial magnetic fields, they go to a saturation value. The growth rate and resonance frequency saturation values are exactly the same as those for infinite axial magnetic field approximation. The effects of electron beam self-fields on growth rate are investigated, and it is shown that the growth rate decreases in the presence of self-fields. It is found that there is an optimum value for electron beam density and Lorentz relativistic factor at which the maximum growth rate can take place. Also, the effects of velocity spread of electron beam are studied and it is found that the growth rate decreases due to the electron velocity spread.

Kheiri, Golshad; Esmaeilzadeh, Mahdi [Department of Physics, Iran University of Science and Technology, Tehran 16844 (Iran, Islamic Republic of)] [Department of Physics, Iran University of Science and Technology, Tehran 16844 (Iran, Islamic Republic of)

2013-12-15T23:59:59.000Z

314

Arrangement for measuring the field angle of a magnetic field as a function of axial position within a magnet bore tube  

DOE Patents [OSTI]

An arrangement for measuring the field angle of a magnetic field as a function of axial position within a magnet bore tube of a magnet such as is used with the Superconducting Super Collider (SSC). The arrangement includes a magnetic field alignment gauge that is carried through the magnet bore tube by a positioning shuttle in predetermined increments. The positioning shuttle includes an extensible body assembly which is actuated by an internal piston arrangement. A pair of spaced inflatable cuffs are carried by the body assembly and are selectively actuated in cooperation with pressurizing of the piston to selectively drive the positioning shuttle in an axial direction. Control of the shuttle is provided by programmed electronic computer means located exteriorly of the bore tube and which controls valves provided pressurized fluid to the inflatable cuss and the piston arrangement.

Pidcoe, Stephen V. (Bonita, CA); Zink, Roger A. (Desoto, TX); Boroski, William N. (Aurora, IL); McCaw, William R. (Burr Ridge, IL)

1993-01-01T23:59:59.000Z

315

Emergence of magnetic field due to spin-polarized baryon matter in neutron stars  

E-Print Network [OSTI]

A model of the ferromagnetic origin of magnetic fields of neutron stars is considered. In this model, the magnetic phase transition occurs inside the core of neutron stars soon after formation. However, owing to the high electrical conductivity the core magnetic field is initially fully screened. We study how this magnetic field emerges for an outside observer. After some time, the induced field that screens the ferromagnetic field decays enough to uncover a detectable fraction of the ferromagnetic field. We conjecture that weak fields of millisecond pulsars of 10^8-10^9 G could be identified with ferromagnetic fields of unshielded fraction f=10^-4 resulting from the decay of screening fields by a factor 1-f in 10^8 yr since their birth.

M. Kutschera

1999-07-28T23:59:59.000Z

316

Chiral dynamics in a magnetic field from the functional renormalization group  

E-Print Network [OSTI]

We investigate the quark-meson model in a magnetic field using the exact functional renormalization group equation beyond the local-potential approximation. Our truncation of the effective action involves anisotropic wave function renormalization for mesons, which allows us to investigate how the magnetic field distorts the propagation of neutral mesons. Solving the flow equation numerically, we find that the transverse velocity of mesons decreases with the magnetic field at all temperatures, which is most prominent at zero temperature. The meson screening masses and the pion decay constants are also computed. The constituent quark mass is found to increase with magnetic field at all temperatures, resulting in the crossover temperature that increases monotonically with the magnetic field. This tendency is consistent with most model calculations but not with the lattice simulation performed at the physical point. Our work suggests that the strong anisotropy of meson propagation may not be the fundamental origin of the inverse magnetic catalysis.

Kazuhiko Kamikado; Takuya Kanazawa

2014-03-13T23:59:59.000Z

317

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

SciTech Connect (OSTI)

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

Woolley, R.D.

1996-12-31T23:59:59.000Z

318

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

SciTech Connect (OSTI)

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

Woolley, Robert D. (Hillsborough, NJ)

1998-01-01T23:59:59.000Z

319

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

DOE Patents [OSTI]

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

Woolley, R.D.

1998-09-08T23:59:59.000Z

320

CHARACTERISTICS AND EVOLUTION OF THE MAGNETIC FIELD AND CHROMOSPHERIC EMISSION IN AN ACTIVE REGION CORE OBSERVED BY HINODE  

SciTech Connect (OSTI)

We describe the characteristics and evolution of the magnetic field and chromospheric emission in an active region core observed by the Solar Optical Telescope (SOT) on Hinode. Consistent with previous studies, we find that the moss is unipolar, the spatial distribution of magnetic flux evolves slowly, and that the magnetic field is only moderately inclined. We also show that the field-line inclination and horizontal component are coherent, and that the magnetic field is mostly sheared in the inter-moss regions where the highest magnetic flux variability is seen. Using extrapolations from spectropolarimeter magnetograms, we show that the magnetic connectivity in the moss is different from that in the quiet Sun because most of the magnetic field extends to significant coronal heights. The magnetic flux, field vector, and chromospheric emission in the moss also appear highly dynamic but actually show only small-scale variations in magnitude on timescales longer than the cooling times for hydrodynamic loops computed from our extrapolations, suggesting high-frequency (continuous) heating events. Some evidence is found for flux (Ca II intensity) changes on the order of 100-200 G (DN) on timescales of 20-30 minutes that could be taken as indicative of low-frequency heating. We find, however, that only a small fraction (10%) of our simulated loops would be expected to cool on these timescales, and we do not find clear evidence that the flux changes consistently produce intensity changes in the chromosphere. Using observations from the EUV Imaging Spectrometer (EIS), we also determine that the filling factor in the moss is {approx}16%, consistent with previous studies and larger than the size of an SOT pixel. The magnetic flux and chromospheric intensity in most individual SOT pixels in the moss vary by less than {approx}20% and {approx}10%, respectively, on loop cooling timescales. In view of the high energy requirements of the chromosphere, we suggest that these variations could be sufficient for the heating of 'warm' EUV loops, but that the high basal levels may be more important for powering the hot core loops rooted in the moss. The magnetic field and chromospheric emission appear to evolve gradually on spatial scales comparable to the cross-field scale of the fundamental coronal structures inferred from EIS measurements.

Brooks, David H.; Warren, Harry P. [Space Science Division, Code 7673, Naval Research Laboratory, Washington, DC 20375 (United States); Winebarger, Amy R., E-mail: dhbrooks@ssd5.nrl.navy.mi [Department of Physics, Alabama A and M, 4900 Meridian Street, Normal, AL 35762 (United States)

2010-09-10T23:59:59.000Z

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

Cosmic rays and the magnetic field of the nearby starburst galaxy NGC 253  

E-Print Network [OSTI]

Using radio polarimetry we study the connection between the transport of cosmic rays (CR's), the three-dimensional magnetic field structure, and features of other ISM phases in the halo of NGC 253. We present a new sensitive radio continuum map of NGC 253 obtained from combined VLA and Effelsberg observations at lambda 6.2 cm. We find a prominent radio halo with a scaleheight of the thick radio disk of 1.7 kpc. The linear dependence between the local scaleheight of the vertical continuum emission and the cosmic ray electron (CRE) lifetime requires a vertical CR bulk speed of 270 km s^-1. The magnetic field structure of NGC 253 resembles an ``X''-shaped configuration where the orientation of the large-scale magnetic field is plane-parallel only in the inner regions of the disk and at small distances from the galactic midplane. At larger galactocentric radii and further away from the midplane the vertical component becomes important. This is most clearly visible at the location of the ``radio spur'' southeast of the nucleus, where the magnetic field orientation is almost vertical. We made a simple model for the dominant toroidal (r,phi) magnetic field component using a spiral magnetic field with prescribed inclination and pitch angle. The residual poloidal (r,phi,z) magnetic field component which was revealed by subtracting the model from the observations shows a distinct ``X''-shaped magnetic field orientation centered on the nucleus. The orientation angle of the poloidal magnetic field is consistent with a magnetic field transport described by the superposition of the vertical CR bulk speed and the rotation velocity. Hence, we propose a disk wind which transports cosmic rays, magnetic field, and (partially) ionized gas from the disk into the halo.

V. Heesen; R. -J. Dettmar; M. Krause; R. Beck

2008-01-23T23:59:59.000Z

322

ON THE AMPLIFICATION OF MAGNETIC FIELD BY A SUPERNOVA BLAST SHOCK WAVE IN A TURBULENT MEDIUM  

SciTech Connect (OSTI)

We have performed extensive two-dimensional magnetohydrodynamic simulations to study the amplification of magnetic fields when a supernova blast wave propagates into a turbulent interstellar plasma. The blast wave is driven by injecting high pressure in the simulation domain. The interstellar magnetic field can be amplified by two different processes, occurring in different regions. One is facilitated by the fluid vorticity generated by the 'rippled' shock front interacting with the background turbulence. The resulting turbulent flow keeps amplifying the magnetic field, consistent with earlier work. The other process is facilitated by the growth of the Rayleigh-Taylor instability at the contact discontinuity between the ejecta and the shocked medium. This can efficiently amplify the magnetic field and tends to produce the highest magnetic field. We investigate the dependence of the amplification on numerical parameters such as grid-cell size and on various physical parameters. We show that the magnetic field has a characteristic radial profile such that the downstream magnetic field gets progressively stronger away from the shock. This is because the downstream magnetic field needs a finite time to reach the efficient amplification, and will get further amplified in the Rayleigh-Taylor region. In our simulation, we do not observe a systematic strong magnetic field within a small distance to the shock. This indicates that if the magnetic-field amplification in supernova remnants indeed occurs near the shock front, other processes such as three-dimensional instabilities, plasma kinetics, and/or cosmic ray effect may need to be considered to explain the strong magnetic field in supernova remnants.

Guo Fan; Li Shengtai; Li Hui; Li, David [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Giacalone, Joe; Jokipii, J. R. [Department of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721 (United States)

2012-03-10T23:59:59.000Z

323

THE OUTBURST DECAY OF THE LOW MAGNETIC FIELD MAGNETAR SGR 0418+5729  

SciTech Connect (OSTI)

We report on the long-term X-ray monitoring of the outburst decay of the low magnetic field magnetar SGR 0418+5729 using all the available X-ray data obtained with RXTE, Swift, Chandra, and XMM-Newton observations from the discovery of the source in 2009 June up to 2012 August. The timing analysis allowed us to obtain the first measurement of the period derivative of SGR 0418+5729: P-dot =4(1) Multiplication-Sign 10{sup -15} s s{sup -1}, significant at a {approx}3.5{sigma} confidence level. This leads to a surface dipolar magnetic field of B{sub dip} {approx_equal} 6 Multiplication-Sign 10{sup 12} G. This measurement confirms SGR 0418+5729 as the lowest magnetic field magnetar. Following the flux and spectral evolution from the beginning of the outburst up to {approx}1200 days, we observe a gradual cooling of the tiny hot spot responsible for the X-ray emission, from a temperature of {approx}0.9 to 0.3 keV. Simultaneously, the X-ray flux decreased by about three orders of magnitude: from about 1.4 Multiplication-Sign 10{sup -11} to 1.2 Multiplication-Sign 10{sup -14} erg s{sup -1} cm{sup -2}. Deep radio, millimeter, optical, and gamma-ray observations did not detect the source counterpart, implying stringent limits on its multi-band emission, as well as constraints on the presence of a fossil disk. By modeling the magneto-thermal secular evolution of SGR 0418+5729, we infer a realistic age of {approx}550 kyr, and a dipolar magnetic field at birth of {approx}10{sup 14} G. The outburst characteristics suggest the presence of a thin twisted bundle with a small heated spot at its base. The bundle untwisted in the first few months following the outburst, while the hot spot decreases in temperature and size. We estimate the outburst rate of low magnetic field magnetars to be about one per year per galaxy, and we briefly discuss the consequences of such a result in several other astrophysical contexts.

Rea, N.; Papitto, A.; Terreran, G.; Girart, J. M.; Palau, Aina; Caliandro, G. A. [Institute of Space Sciences (CSIC-IEEC), Campus UAB, Faculty of Science, Torre C5-parell, E-08193 Barcelona (Spain); Israel, G. L. [INAF/Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone (Italy); Pons, J. A.; Vigano, D. [Department de Fisica Aplicada, Universitat d'Alacant, Ap. Correus 99, E-03080 Alacant (Spain); Turolla, R. [Dipartimento di Fisica e Astronomia, Universita di Padova, via F. Marzolo 8, I-35131 Padova (Italy); Zane, S. [Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT (United Kingdom); Esposito, P.; Tiengo, A.; Salvetti, D. [INAF/Istituto di Astrofisica Spaziale e Fisica Cosmica-Milano, via E. Bassini 15, I-20133 Milano (Italy); Perna, R. [JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States); Possenti, A.; Burgay, M. [INAF/Osservatorio Astronomico di Cagliari, localita Poggio dei Pini, strada 54, I-09012 Capoterra (Italy); Goegues, E. [Sabanc Latin-Small-Letter-Dotless-I University, Orhanl Latin-Small-Letter-Dotless-I -Tuzla, 34956 Istanbul (Turkey); Kouveliotou, C. [NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Goetz, D. [AIM (UMR 7158 CEA/DSM-CNRS-Universite Paris Diderot) Irfu/Service d'Astrophysique, Saclay, F-91191 Gif-sur-Yvette Cedex (France); and others

2013-06-10T23:59:59.000Z

324

Nonideal evolution of nonaxisymmetric, force-free magnetic fields in a magnetar  

E-Print Network [OSTI]

Recent numerical magnetohydrodynamic calculations by Braithwaite and collaborators support the `fossil field' hypothesis regarding the origin of magnetic fields in compact stars and suggest that the resistive evolution of the fossil field can explain the reorganisation and decay of magnetar magnetic fields. Here, these findings are modelled analytically by allowing the stellar magnetic field to relax through a quasistatic sequence of nonaxisymmetric, force-free states, by analogy with spheromak relaxation experiments, starting from a random field. Under the hypothesis that the force-free modes approach energy equipartition in the absence of resistivity, the output of the numerical calculations is semiquantitatively recovered: the field settles down to a linked poloidal-toroidal configuration, which inflates and becomes more toroidal as time passes. A qualitatively similar (but not identical) end state is reached if the magnetic field evolves by exchanging helicity between small and large scales according to a...

Mastrano, Alpha

2008-01-01T23:59:59.000Z

325

Internal magnetic field structure and parallel electric field profile evolution during the sawtooth cycle in MST  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsingFunInfrared LandResponses to Engineered Nanomaterials: The541990magnetic field

326

Evidence for a devil's staircase in holmium produced by an applied magnetic field  

SciTech Connect (OSTI)

The magnetic structure of holmium has been studied using neutron diffraction when a magnetic field is applied along the {ital c} axis. The field has the effect of suppressing the onset of the commensurate cone phase found at low temperatures in zero field, and instead produces a series of spin-slip structures. In contrast to the zero-field diffraction experiments, where a continuous variation of the magnetic wave vector {bold q} was observed, we find that below {approx}15 K the wave vector {bold q} is always commensurate and forms a devil's staircase with increasing field.

Cowley, R.A.; Jehan, D.A. (Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford (United Kingdom)); McMorrow, D.F. (Department of Physics, University of Edinburgh, Mayfield Road, Edinburgh, Scotland (United Kingdom)); McIntyre, G.J. (Institut Laue-Langevin, 156X, 38042, Grenoble, CEDEX (France))

1991-03-18T23:59:59.000Z

327

LDRD final report on confinement of cluster fusion plasmas with magnetic fields.  

SciTech Connect (OSTI)

Two versions of a current driver for single-turn, single-use 1-cm diameter magnetic field coils have been built and tested at the Sandia National Laboratories for use with cluster fusion experiments at the University of Texas in Austin. These coils are used to provide axial magnetic fields to slow radial loss of electrons from laser-produced deuterium plasmas. Typical peak field strength achievable for the two-capacitor system is 50 T, and 200 T for the ten-capacitor system. Current rise time for both systems is about 1.7 {mu}s, with peak current of 500 kA and 2 MA, respectively. Because the coil must be brought to the laser, the driver needs to be portable and drive currents in vacuum. The drivers are complete but laser-plasma experiments are still in progress. Therefore, in this report, we focus on system design, initial tests, and performance characteristics of the two-capacitor and ten-capacitors systems. The questions of whether a 200 T magnetic field can retard the breakup of a cluster-fusion plasma, and whether this field can enhance neutron production have not yet been answered. However, tools have been developed that will enable producing the magnetic fields needed to answer these questions. These are a two-capacitor, 400-kA system that was delivered to the University of Texas in 2010, and a 2-MA ten-capacitor system delivered this year. The first system allowed initial testing, and the second system will be able to produce the 200 T magnetic fields needed for cluster fusion experiments with a petawatt laser. The prototype 400-kA magnetic field driver system was designed and built to test the design concept for the system, and to verify that a portable driver system could be built that delivers current to a magnetic field coil in vacuum. This system was built copying a design from a fixed-facility, high-field machine at LANL, but made to be portable and to use a Z-machine-like vacuum insulator and vacuum transmission line. This system was sent to the University of Texas in Austin where magnetic fields up to 50 T have been produced in vacuum. Peak charge voltage and current for this system have been 100 kV and 490 kA. It was used this last year to verify injection of deuterium and surrogate clusters into these small, single-turn coils without shorting the coil. Initial test confirmed the need to insulate the inner surface of the coil, which requires that the clusters must be injected through small holes in an insulator. Tests with a low power laser confirmed that it is possible to inject clusters into the magnetic field coils through these holes without destroying the clusters. The university team also learned the necessity of maintaining good vacuum to avoid insulator, transmission line, and coil shorting. A 200-T, 2 MA system was also constructed using the experience from the first design to make the pulsed-power system more robust. This machine is a copy of the prototype design, but with ten 100-kV capacitors versus the two used in the prototype. It has additional inductance in the switch/capacitor unit to avoid breakdown seen in the prototype design. It also has slightly more inductance at the cable connection to the vacuum chamber. With this design we have been able to demonstrate 1 MA current into a 1 cm diameter coil with the vacuum chamber at air pressure. Circuit code simulations, including the additional inductance with the new design, agree well with the measured current at a charge voltage of 40 kV with a short circuit load, and at 50 kV with a coil. The code also predicts that with a charge voltage of 97 kV we will be able to get 2 MA into a 1 cm diameter coil, which will be sufficient for 200 T fields. Smaller diameter or multiple-turn coils will be able to achieve even higher fields, or be able to achieve 200-T fields with lower charge voltage. Work is now proceeding at the university under separate funding to verify operation at the 2-MA level, and to address issues of debris mitigation, measurement of the magnetic field, and operation in vacuum. We anticipate operation at full current with single

Argo, Jeffrey W.; Kellogg, Jeffrey W.; Headley, Daniel Ignacio; Stoltzfus, Brian Scott; Waugh, Caleb J.; Lewis, Sean M.; Porter, John Larry, Jr.; Wisher, Matthew; Struve, Kenneth William; Savage, Mark Edward; Quevedo, Hernan J.; Bengtson, Roger

2011-11-01T23:59:59.000Z

328

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

329

Gas Kinetic Study of Magnetic Field Effects on Plasma Plumes  

E-Print Network [OSTI]

Plasma flow physics in magnetic nozzles must be clearly understood for optimal design of plasma propulsion devices. Toward that end, in this thesis we: i) perform an extensive literature survey of magnetic nozzle physics, ii) assess the validity...

Ebersohn, Frans 1987-

2012-12-07T23:59:59.000Z

330

Presented by the National High Magnetic Field Laboratory  

E-Print Network [OSTI]

! Cooling holes on the Bitter plates let cold water run through the magnet so it doesn't get too hot. l magnets found in houses. The answers will fit into the crossword puzzle below. ACROSS Where you store milk

Weston, Ken

331

ac magnetic field: Topics by E-print Network  

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

contract No. DE-AC02-76CH00016. Abstract A common coil design concept for 2-in-1 superconduct- ing Gupta, Ramesh 126 Anisotropy of magnetic emulsions induced by magnetic and...

332

ac magnetic fields: Topics by E-print Network  

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

contract No. DE-AC02-76CH00016. Abstract A common coil design concept for 2-in-1 superconduct- ing Gupta, Ramesh 126 Anisotropy of magnetic emulsions induced by magnetic and...

333

Nonlinear force-free modeling of the solar coronal magnetic field  

E-Print Network [OSTI]

The coronal magnetic field is an important quantity because the magnetic field dominates the structure of the solar corona. Unfortunately direct measurements of coronal magnetic fields are usually not available. The photospheric magnetic field is measured routinely with vector magnetographs. These photospheric measurements are extrapolated into the solar corona. The extrapolated coronal magnetic field depends on assumptions regarding the coronal plasma, e.g. force-freeness. Force-free means that all non-magnetic forces like pressure gradients and gravity are neglected. This approach is well justified in the solar corona due to the low plasma beta. One has to take care, however, about ambiguities, noise and non-magnetic forces in the photosphere, where the magnetic field vector is measured. Here we review different numerical methods for a nonlinear force-free coronal magnetic field extrapolation: Grad-Rubin codes, upward integration method, MHD-relaxation, optimization and the boundary element approach. We briefly discuss the main features of the different methods and concentrate mainly on recently developed new codes.

T. Wiegelmann

2008-01-18T23:59:59.000Z

334

Stellar Magnetic Fields as a Heating Source for Extrasolar Giant Planets  

E-Print Network [OSTI]

It has been observed that hot Jupiters located within 0.08 AU of their host stars commonly display radii in excess of those expected based on models. A number of theoretical explanations for this phenomenon have been suggested, but the ability of any one mechanism to account for the full range of observations remains to be rigorously proven. I identify an additional heating mechanism, arising from the interaction of the interplanetary magnetic field and the planetary magnetosphere, and show that this is capable of providing enough energy to explain the observed planetary radii. Such a model predicts that the degree of heating should be dependent on the stellar magnetic field, for which stellar activity serves as a proxy. Accordingly, I examine populations of hot Jupiters from the Kepler database and confirm that stellar activity (determined using Kepler CDPP levels) is correlated with the presence of planetary radii inflated beyond the basal level of R = 0.87 R_J identified by previous researchers. I propose ...

Buzasi, D

2013-01-01T23:59:59.000Z

335

Spectro-polarimetric Imaging Reveals Helical Magnetic Fields in Solar Prominence Feet  

E-Print Network [OSTI]

Solar prominences are clouds of cool plasma levitating above the solar surface and insulated from the million-degree corona by magnetic fields. They form in regions of complex magnetic topology, characterized by non-potential fields, which can evolve abruptly, disintegrating the prominence and ejecting magnetized material into the heliosphere. However, their physics is not yet fully understood because mapping such complex magnetic configurations and their evolution is extremely challenging, and must often be guessed by proxy from photometric observations.Using state-of-the-art spectro-polarimetric data, we reconstruct the structure of the magnetic field in a prominence. We find that prominence feet harbor helical magnetic fields connecting the prominence to the solar surface below.

Gonzalez, M J Martinez; Ramos, A Asensio; Beck, C; Rodriguez, J de la Cruz; Diaz, A J

2015-01-01T23:59:59.000Z

336

Thermodynamic functions of a nonrelativistic degenerate neutron gas in a magnetic field  

SciTech Connect (OSTI)

The Fermi energy, partial concentrations of polarized neutrons, pressure, and volume energy density of a degenerate nonrelativistic neutron gas in a magnetic field are calculated using numerical methods taking into account the anomalous magnetic moment of a neutron. The results of calculations are a generalization of relations underlying the Oppenheimer-Volkov model of a neutron star to the case of an applied magnetic field. An ultrastrong (up to 10{sup 17} G) magnetic field changes the pressure and internal energy of the star and affects it static configuration and evolution. It is shown that a degenerate neutron gas in ultrastrong and weak magnetic fields is paramagnetic; the corresponding values of magnetic susceptibility differ by a factor on the order of unity. The possibility of experimentally verifying the results from analysis of pulsar-emitted radiation is discussed.

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

2010-01-15T23:59:59.000Z

337

Magnetic field distribution in the plasma flow generated by a plasma focus discharge  

SciTech Connect (OSTI)

The magnetic field in the plasma jet propagating from the plasma pinch region along the axis of the chamber in a megajoule PF-3 plasma focus facility is studied. The dynamics of plasma with a trapped magnetic flow is analyzed. The spatial sizes of the plasma jet region in which the magnetic field concentrates are determined in the radial and axial directions. The magnetic field configuration in the plasma jet is investigated: the radial distribution of the azimuthal component of the magnetic field inside the jet is determined. It is shown that the magnetic induction vector at a given point in space can change its direction during the plasma flight. Conclusions regarding the symmetry of the plasma flow propagation relative to the chamber axis are drawn.

Mitrofanov, K. N., E-mail: mitrofan@triniti.ru [Troitsk Institute for Innovaiton and Fusion Research (Russian Federation); Krauz, V. I., E-mail: krauz_vi@nrcki.ru; Myalton, V. V.; Velikhov, E. P.; Vinogradov, V. P.; Vinogradova, Yu. V. [National Research Centre Kurchatov Institute (Russian Federation)

2014-11-15T23:59:59.000Z

338

The Evolution of Cosmic Magnetic Fields: From the Very Early Universe, to Recombination, to the Present  

E-Print Network [OSTI]

(abridged) A detailed examination of the evolution of stochastic magnetic fields between high cosmic temperatures and the present epoch is presented. A simple analytical model matching the results of the 3D MHD simulations allows for the prediction of present day magnetic field correlation lengths and energy. Our conclusions are multi fold. (a) Initial primordial fields with only a small amount of helicity are evolving into maximally helical fields. (b) There exists a correlation between the strength of the magnetic field, B, at the peak of it's spectrum and the location of the peak, given at the present epoch by: B ~ 5x10^{-12} (L/kpc) Gauss, where L is the correlation length determined by the initial magnetic field. (c) Concerning studies of generation of cosmic microwave background (CMBR) anisotropies due to primordial magnetic fields of B~10^{-9} Gauss on ~ 10 Mpc scales, such fields are not only impossible to generate in early causal magnetogenesis scenarios but also seemingly ruled out by distortions of the CMBR spectrum due to magnetic field dissipation on smaller scales and the overproduction of cluster magnetic fields. (d) The most promising detection possibility of CMBR distortions due to primordial magnetic fields may be on much smaller scales at higher multipoles l~10^6 where the signal is predicted to be the strongest. (e) It seems possible that magnetic fields in clusters of galaxies are entirely of primordial origin, without invoking dynamo amplification. Such fields would be of (pre-collapse) strength 10^{-12} - 10^{-11} Gauss with correlation lengths in the kpc range, and would also exist in voids of galaxies.

Robi Banerjee; Karsten Jedamzik

2004-10-01T23:59:59.000Z

339

Shell-instability generated waves by low energy electrons on converging magnetic field lines  

E-Print Network [OSTI]

Shell-instability generated waves by low energy electrons on converging magnetic field lines D of observations of such shell type distributions having positive slope in velocity space at low energies, about 10´cre´au (2006), Shell-instability generated waves by low energy electrons on converging magnetic field lines

California at Berkeley, University of

340

Plasma transport in a converging magnetic field with applications to helicon plasma thrusters  

E-Print Network [OSTI]

.1, which represents a new design criteria for helicon plasma thrusters. I. Introduction ElectrodelessPlasma transport in a converging magnetic field with applications to helicon plasma thrusters IEPC University, Princeton, New Jersey, 08540, USA Plasma transport in the convergent magnetic field region

Choueiri, Edgar

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

NORDITA-2014-17 Evolution of the Magnetic Field Generated by the Kelvin-Helmholtz Instability  

E-Print Network [OSTI]

in geophysical and astrophysical flows, from ocean surface waves exited by wind, turbu- lent jets and wakes, upNORDITA-2014-17 Evolution of the Magnetic Field Generated by the Kelvin-Helmholtz Instability M of magnetic field via the Biermann battery mechanisms. The problem is studied through direct numerical

Brandenburg, Axel

342

Scattering of Polarized Radiation by Atoms in Magnetic and Electric Fields  

E-Print Network [OSTI]

The polarization of radiation by scattering on an atom embedded in combined external quadrupole electric and uniform magnetic fields is studied theoretically. Analytic formulae are derived for the scattering phase matrix. Limiting cases of scattering under Zeeman effect, and Hanle effect in weak magnetic fields are discussed.

Yee Yee Oo; K. N. Nagendra; Sharath Ananthamurthy; G. Ramachandran

2005-09-26T23:59:59.000Z

343

Remote control of ion channels and neurons through magnetic-field heating of nanoparticles  

E-Print Network [OSTI]

Remote control of ion channels and neurons through magnetic-field heating of nanoparticles Heng. Here, we show an approach based on radio-frequency magnetic-field heating of nanoparticles to remotely targeted to specific proteins on the plasma membrane of cells expressing TRPV1, and heated by a radio

Ferkey, Denise

344

General relativistic simulations of black hole-neutron star mergers: Effects of magnetic fields  

E-Print Network [OSTI]

As a neutron star (NS) is tidally disrupted by a black hole (BH) companion at the end of a BH-NS binary inspiral, its magnetic fields will be stretched and amplified. If sufficiently strong, these magnetic fields may impact the gravitational waveforms, merger evolution and mass of the remnant disk. Formation of highly-collimated magnetic field lines in the disk+spinning BH remnant may launch relativistic jets, providing the engine for a short-hard GRB. We analyze this scenario through fully general relativistic, magnetohydrodynamic (GRMHD) BHNS simulations from inspiral through merger and disk formation. Different initial magnetic field configurations and strengths are chosen for the NS interior for both nonspinning and moderately spinning (a/M=0.75) BHs aligned with the orbital angular momentum. Only strong interior (Bmax~10^17 G) initial magnetic fields in the NS significantly influence merger dynamics, enhancing the remnant disk mass by 100% and 40% in the nonspinning and spinning BH cases, respectively. However, detecting the imprint of even a strong magnetic field may be challenging for Advanced LIGO. Though there is no evidence of mass outflows or magnetic field collimation during the preliminary simulations we have performed, higher resolution, coupled with longer disk evolutions and different initial magnetic field configurations, may be required to definitively assess the possibility of BHNS binaries as short-hard GRB progenitors.

Zachariah B. Etienne; Yuk Tung Liu; Vasileios Paschalidis; Stuart L. Shapiro

2012-05-15T23:59:59.000Z

345

NHMFL Breaks the 100 Tesla Barrier Gregory S. Boebinger, National High Magnetic Field Laboratory  

E-Print Network [OSTI]

NHMFL Breaks the 100 Tesla Barrier Gregory S. Boebinger, National High Magnetic Field Laboratory. 109no. 31 12404-12407 On March 22nd 2012, the NHMFL ­ Pulsed Field Facility broke the 100T tesla barrier, setting a world record of 100.75 tesla for a non-destructive magnet. By using advanced

Weston, Ken

346

A planar ion trap chip with integrated structures for an adjustable magnetic field gradient  

E-Print Network [OSTI]

field necessary for magnetic-gradient- induced coupling between ionic effective spins. We dem- onstrate] magnetic field gradient, however, such coupling is induced. Also, coupling between spin states of different-gradient- induced coupling (MAGIC). A static gradient can be generated by permanent mag- nets [15, 16] or by current

Wunderlich, Christof

347

Electron acceleration by a plasma wave in a sheared magnetic field K. P. Singha)  

E-Print Network [OSTI]

Electron acceleration by a plasma wave in a sheared magnetic field K. P. Singha) and V. L. Gupta Department of Electronic Science, University of Delhi, New Delhi-110021, India Lalita Bhasin and V. K, the acceleration of electrons by a plasma wave, in the presence of a sheared magnetic field a slab model

Singh, Kunwar Pal

348

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

E-Print Network [OSTI]

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

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

2010-08-16T23:59:59.000Z

349

The magnetic field of the planet-hosting star $\\tau$ Bootis  

E-Print Network [OSTI]

We have obtained high resolution spectropolarimetric data for the planet-hosting star $\\tau$ Bootis, using the ESPaDOnS spectropolarimeter at CFHT. A weak but clear Stokes $V$ signature is detected on three of the four nights of June 2006 during which we have recorded data. This polarimetric signature indicates with no ambiguity the presence of a magnetic field at the star's surface, with intensity of just a few Gauss. The analysis of the photospheric lines of $\\tau$ Boo at ultra-high signal-to-noise reveals the presence of an 18% relative differential rotation. Tentative Zeeman-Doppler imaging, using our spectropolarimetric observations covering only a fraction of the star's rotational phase, indicates a magnetic field with a dominant potential field component. The data are best fitted when a 3.1d period of modulation and an intermediate inclination are assumed. Considering the level of differential rotation of $\\tau$ Boo, this implies a rotation period of 3.0d at the equator and of 3.7d at the pole, and a t...

Catala, C; Shkolnik, E; Bohlender, D A; Alecian, E

2006-01-01T23:59:59.000Z

350

Steel characteristics measurement system using Barkhausen jump sum rate and magnetic field intensity and method of using same  

DOE Patents [OSTI]

A steel hardness measurement system and method of using same are provided for measuring at least one mechanical or magnetic characteristic of a ferromagnetic sample as a function of at least one magnetic characteristic of the sample. A magnetic field generator subjects the sample to a variable external magnetic field. The magnetic field intensity of the magnetic field generated by the magnetic field generating means is measured and a signal sensor is provided for measuring Barkhausen signals from the sample when the sample is subjected to the external magnetic field. A signal processing unit calculates a jump sum rate first moment as a function of the Barkhausen signals measured by the signal sensor and the magnetic field intensity, and for determining the at least one mechanical or magnetic characteristic as a function of the jump sum rate first moment.

Kohn, Gabriel (Omer, IL); Hicho, George (Derwood, MD); Swartzendruber, Lydon (New Carrollton, MD)

1997-01-01T23:59:59.000Z

351

Steel characteristics measurement system using Barkhausen jump sum rate and magnetic field intensity and method of using same  

DOE Patents [OSTI]

A steel hardness measurement system and method of using same are provided for measuring at least one mechanical or magnetic characteristic of a ferromagnetic sample as a function of at least one magnetic characteristic of the sample. A magnetic field generator subjects the sample to a variable external magnetic field. The magnetic field intensity of the magnetic field generated by the magnetic field generating means is measured and a signal sensor is provided for measuring Barkhausen signals from the sample when the sample is subjected to the external magnetic field. A signal processing unit calculates a jump sum rate first moment as a function of the Barkhausen signals measured by the signal sensor and the magnetic field intensity, and for determining the at least one mechanical or magnetic characteristic as a function of the jump sum rate first moment. 7 figs.

Kohn, G.; Hicho, G.; Swartzendruber, L.

1997-04-08T23:59:59.000Z

352

Passive Superconducting Flux Conservers for Rotating-Magnetic-Field-Driven Field-Reversed Configurations  

SciTech Connect (OSTI)

The Princeton Field-Reversed Configuration (PFRC) experiment employs an odd-parity rotating magnetic field (RMFo) current drive and plasma heating system to form and sustain high-? plasmas. For radial confinement, an array of coaxial, internal, passive, flux-conserving (FC) rings applies magnetic pressure to the plasma while still allowing radio-frequency RMFo from external coils to reach the plasma. The 3 ms pulse duration of the present experiment is limited by the skin time (?fc) of its room-temperature copper FC rings. To explore plasma phenomena with longer characteristic times, the pulse duration of the next-generation PFRC-2 device will exceed 100 ms, necessitating FC rings with (?fc > 300 ms. In this paper we review the physics of internal, discrete, passive FCs and describe the evolution of the PFRC's FC array. We then detail new experiments that have produced higher performance FC rings that contain embedded high-temperature superconducting (HTS) tapes. Several HTS tape winding configurations have been studied and a wide range of extended skin times, from 0.4 s to over 103 s, has been achieved. The new FC rings must carry up to 3 kA of current to balance the expected PFRC-2 plasma pressure, so the dependence of the HTS-FC critical current on the winding configuration and temperature was also studied. From these experiments, the key HTS-FC design considerations have been identified and HTS-FC rings with the desired performance characteristics have been produced.

E. Oz, C.E. Myers, M.R. Edwards, B. Berlinger, A. Brooks, and S.A. Cohen

2011-01-05T23:59:59.000Z

353

New High Field Magnet for Neutron Scattering at Hahn-Meitner Institute  

E-Print Network [OSTI]

Abstract. The Berlin Neutron Scattering Center BENSC at the Hahn-Meitner-Institute (HMI) is a user facility for the study of structure and dynamics of condensed matter with neutrons and synchrotron radiation with special emphasis on experiments under extreme conditions. Neutron scattering is uniquely suited to study magnetic properties on a microscopic length scale, because neutrons have comparable wavelengths and, due to their magnetic moment, they interact with the atomic magnetic moments. Magnetic interactions and magnetic phenomena depend on thermodynamic parameters like magnetic field, temperature and pressure. At HMI special efforts are being made to offer outstanding sample environments such as very low temperatures or high magnetic fields or combination of both. For the future a dedicated instrument for neutron scattering at extreme fields is under construction, the Extreme Environment Diffractometer ExED. For this instrument the existing superconducting magnets as well as a future hybrid system can be used. The highest fields, above 30 T will be produced by the planned series-connected hybrid magnet system, designed and constructed in collaboration with the National High Magnetic Field Laboratory, Tallahassee, FL. 1.

M Steiner; D A Tennant; P Smeibidl

354

The Magnificent Seven: Magnetic fields and surface temperature distributions  

E-Print Network [OSTI]

Presently seven nearby radio-quiet isolated neutron stars discovered in ROSAT data and characterized by thermal X-ray spectra are known. They exhibit very similar properties and despite intensive searches their number remained constant since 2001 which led to their name ``The Magnificent Seven''. Five of the stars exhibit pulsations in their X-ray flux with periods in the range of 3.4 s to 11.4 s. XMM-Newton observations revealed broad absorption lines in the X-ray spectra which are interpreted as cyclotron resonance absorption lines by protons or heavy ions and / or atomic transitions shifted to X-ray energies by strong magnetic fields of the order of 10^13 G. New XMM-Newton observations indicate more complex X-ray spectra with multiple absorption lines. Pulse-phase spectroscopy of the best studied pulsars RX J0720.4-3125 and RBS 1223 reveals variations in derived emission temperature and absorption line depth with pulse phase. Moreover, RX J0720.4-3125 shows long-term spectral changes which are interpreted as due to free precession of the neutron star. Modeling of the pulse profiles of RX J0720.4-3125 and RBS 1223 provides information about the surface temperature distribution of the neutron stars indicating hot polar caps which have different temperatures, different sizes and are probably not located in antipodal positions.

F. Haberl

2006-09-04T23:59:59.000Z

355

Spontaneous and field-induced magnetic transitions in YBaCo2O5.5  

SciTech Connect (OSTI)

A detailed study of magnetic properties of cobaltite YBaCo{sub 2}O{sub 5.5} has been performed in high (up to 35 T) magnetic fields and under hydrostatic pressure up to 0.8 GPa. The temperatures of paramagnet-ferromagnet (PM-FM) and ferromagnet-antiferromagnet (FM-AF) phase transitions and their pressure derivatives have been determined. It has been revealed that in the compound with yttrium, in contrast to those with magnetic rare earth atoms, the AF-FM field-induced magnetic phase transition is accompanied by a considerable field hysteresis below 240 K, and the magnetic field of 35 T is not sufficient to complete this transition at low temperatures. The hysteresis value depends on the magnetic field sweep rate, which considered as an evidence of magnetic viscosity that is especially strong in the region of coexistence of the FM and AF phases. High values of susceptibility for the field-induced FM phase show that Co spin state in these compounds changes in strong magnetic field.

Bobrovskii, Vladimir [Institute of Metal Physics, Russia; Kazantsev, Vadim [Institute of Metal Physics, Russia; Mirmelstein, Aleksey [Institute of Metal Physics, Russia; Mushnikov, Nikolai [Institute of Metal Physics, Russia; Proskurnina, Natalia [Institute of Metal Physics, Russia; Voronin, Vladimir [Institute of Metal Physics, Russia; Pomjakushina, Ekaterina [Paul Scherrer Institut, Villigen, Switzerland; Conder, Kazimierz [Paul Scherrer Institut, Villigen, Switzerland; Podlesnyak, Andrey A [ORNL

2009-01-01T23:59:59.000Z

356

HYPERCRITICAL ACCRETION ONTO A NEWBORN NEUTRON STAR AND MAGNETIC FIELD SUBMERGENCE  

SciTech Connect (OSTI)

We present magnetohydrodynamic numerical simulations of the late post-supernova hypercritical accretion to understand its effect on the magnetic field of the newborn neutron star. We consider as an example the case of a magnetic field loop protruding from the star's surface. The accreting matter is assumed to be non-magnetized, and, due to the high accretion rate, matter pressure dominates over magnetic pressure. We find that an accretion envelope develops very rapidly, and once it becomes convectively stable, the magnetic field is easily buried and pushed into the newly forming neutron star crust. However, for low enough accretion rates the accretion envelope remains convective for an extended period of time and only partial submergence of the magnetic field occurs due to a residual field that is maintained at the interface between the forming crust and the convective envelope. In this latter case, the outcome should be a weakly magnetized neutron star with a likely complicated field geometry. In our simulations we find the transition from total to partial submergence to occur around M-dot {approx}10 M{sub sun} yr{sup -1}. Back-diffusion of the submerged magnetic field toward the surface, and the resulting growth of the dipolar component, may result in a delayed switch-on of a pulsar on timescales of centuries to millennia.

Bernal, Cristian G.; Page, Dany; Lee, William H., E-mail: bernalcg@astro.unam.mx, E-mail: page@astro.unam.mx, E-mail: wlee@astro.unam.mx [Departamento de Astrofisica Teorica, Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Mexico, D.F. 04510 (Mexico)

2013-06-20T23:59:59.000Z

357

Asymmetric neutrino production in magnetized proto-neutron stars in fully relativistic mean-field approach  

SciTech Connect (OSTI)

We calculate the neutrino production cross-section in the proto-neutron-star matter under a strong magnetic field in the relativistic mean-field approach. We introduce a new parameter-set which can reproduce the 1.96 solar mass neutron star. We find that the production process increases emitted neutrinos along the direction parallel to the magnetic field and decrease those along its opposite direction. It means that resultant asymmetry due to the neutrino absorption and scattering process in the magnetic field becomes larger by the addition of the neutrino production process.

Maruyama, Tomoyuki [College of Bioresource Sciences, Nihon University, Fujisawa 252-8510 (Japan); Kajino, Toshitaka; Hidaka, Jun; Takiwaki, Tomoya [National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Yasutake, Nobutoshi [Department of Physics, Chiba Institute of Technology, Narashino 275-0023 (Japan); Kuroda, Takami [Department of Physics, University of Basel, CH-4056 Basel (Switzerland); Cheoun, Myung-Ki [Department of Physics, Soongsil University, Seoul, 156-743 (Korea, Republic of); Ryu, Chung-Yeol [General Education Curriculum Center, Hanyang University, Seoul, 133-791 (Korea, Republic of); Mathews, Grant J. [Center of Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States)

2014-05-02T23:59:59.000Z

358

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

2014-08-26T23:59:59.000Z

359

A loss-based, magnetic field sensor implemented in a ferrofluid infiltrated microstructured polymer optical fiber  

SciTech Connect (OSTI)

We report an in-fiber magnetic field sensor based on magneto-driven optical loss effects, while being implemented in a ferrofluid infiltrated microstructured polymer optical fiber. We demonstrate that magnetic field flux changes up to 2000 gauss can be detected when the magnetic field is applied perpendicular to the fiber axis. In addition, the sensor exhibits high polarization sensitivity for the interrogated wavelengths, providing the possibility of both field flux and direction measurements. The underlying physical and guidance mechanisms of this sensing transduction are further investigated using spectrophotometric, light scattering measurements, and numerical simulations, suggesting photonic Hall effect as the dominant physical, transducing mechanism.

Candiani, A. [Foundation for Research and Technology-Hellas (FORTH), Institute of Electronic Structure and Laser (IESL), Heraklion 70013 Greece (Greece); Department of Information Engineering (DII), University of Parma, Parma 43124 (Italy); Argyros, A.; Leon-Saval, S. G.; Lwin, R. [Institute of Photonics and Optical Science (IPOS), School of Physics, The University of Sydney, Sydney (Australia); Selleri, S. [Department of Information Engineering (DII), University of Parma, Parma 43124 (Italy); Pissadakis, S., E-mail: pissas@iesl.forth.gr [Foundation for Research and Technology-Hellas (FORTH), Institute of Electronic Structure and Laser (IESL), Heraklion 70013 Greece (Greece)

2014-03-17T23:59:59.000Z

360

New measurements of magnetic fields of roAp stars with FORS1 at the VLT  

E-Print Network [OSTI]

Magnetic fields play a key role in the pulsations of rapidly oscillating Ap (roAp) stars since they are a necessary ingredient of all pulsation excitation mechanisms proposed so far. This implies that the proper understanding of the seismological behaviour of the roAp stars requires knowledge of their magnetic fields. However, the magnetic fields of the roAp stars are not well studied. Here we present new results of measurements of the mean longitudinal field of 14 roAp stars obtained from low resolution spectropolarimetry with FORS1 at the VLT.

S. Hubrig; T. Szeifert; M. Schoeller; G. Mathys; D. W. Kurtz

2003-09-21T23:59:59.000Z

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

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

362

Directional properties of polar paramagnetic molecules subject to congruent electric, magnetic and optical fields  

E-Print Network [OSTI]

We show that congruent electric, magnetic and non-resonant optical fields acting concurrently on a polar paramagnetic (and polarisable) molecule offer possibilities to both amplify and control the directionality of the ensuing molecular states that surpass those available in double-field combinations or in single fields alone. At the core of these triple-field effects is the lifting of the degeneracy of the projection quantum number $M$ by the magnetic field superimposed on the optical field and a subsequent coupling of the members of the "doubled" (for states with $M \

Sharma, Ketan

2015-01-01T23:59:59.000Z

363

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

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

Schweigger Multiplier Schweigger Multiplier In 1820, the news that the current traveling through an electrical wire could deflect the magnetic needle of a compass astounded the...

364

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

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

which is why it can be used repeatedly after it has been initially charged via friction. Related Electricity & Magnetism Pages Pioneers: Alessandro Volta Timeline: 1750 ...

365

Ground Magnetics At San Francisco Volcanic Field Area (Warpinski...  

Open Energy Info (EERE)

geologically mapped the target area, obtained rock samples for age dating and mineral chemistry, performed gravity and magnetic surveys, and integrated these results to identify...

366

National High Magnetic Field Laboratory - Series Connected Hybrid...  

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

Spallation Neutron Source Series Connected Hybrid Figure 3. Vertical Section of the Series Connected Hybrid Magnet and Cryostat for the SNS. The SCH for the Spallation Neutron...

367

Measuring Magnetic Fields Near and Far with the SKA via the Zeeman Effect  

E-Print Network [OSTI]

The measurement of Zeeman splitting in spectral lines---both in emission and absorption---can provide direct estimates of the magnetic field strength and direction in atomic and molecular clouds, both in our own Milky Way and in external galaxies. This method will probe the magnetic field in the warm and cold neutral components of the interstellar medium, providing a complement to the extensive SKA Faraday studies planning to probe the field in the ionized components.

Robishaw, Timothy; Surcis, Gabriele; Vlemmings, Wouter; Richards, A M S; Etoka, Sandra; Bourke, Tyler; Fish, Vincent; Gray, Malcolm; Imai, Hiroshi; Kramer, Busaba; McBride, James; Momjian, Emmanuel; Sarma, Anuj; Zijlstra, Albert

2015-01-01T23:59:59.000Z

368

Production of large volume, strongly magnetized laser-produced plasmas by use of pulsed external magnetic fields  

SciTech Connect (OSTI)

The production of strongly magnetized laser plasmas, of interest for laboratory astrophysics and inertial confinement fusion studies, is presented. This is achieved by coupling a 16 kV pulse-power system. This is achieved by coupling a 16 kV pulse-power system, which generates a magnetic field by means of a split coil, with the ELFIE laser facility at Ecole Polytechnique. In order to influence the plasma dynamics in a significant manner, the system can generate, repetitively and without debris, high amplitude magnetic fields (40 T) in a manner compatible with a high-energy laser environment. A description of the system and preliminary results demonstrating the possibility to magnetically collimate plasma jets are given.

Albertazzi, B. [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); INRS-EMT, Varennes, Quebec J3X 1S2 (Canada); Beard, J.; Billette, J.; Portugall, O. [LNCMI, UPR 3228, CNRS-UFJ-UPS-INSA, 31400 Toulouse (France); Ciardi, A. [LERMA, Observatoire de Paris, Ecole Normale Superieure, Universite Pierre et Marie Curie, CNRS UMR 8112, Paris (France); Vinci, T.; Albrecht, J.; Chen, S. N.; Da Silva, D.; Hirardin, B.; Nakatsutsumi, M.; Romagnagni, L.; Simond, S.; Veuillot, E.; Fuchs, J. [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); Burris-Mog, T.; Dittrich, S.; Herrmannsdoerfer, T.; Kroll, F.; Nitsche, S. [Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, 01314 Dresden (Germany); and others

2013-04-15T23:59:59.000Z

369

Magnetic field measurement of superconducting dipolemagnets with harmonic coil and Hall probe  

SciTech Connect (OSTI)

Magnetic field measurements and field analyses of 1-m long superconducting dipole magnets fabricated at the National Laboratory for High Energy Physics (KEK) have been carried out using a harmonic coil with the bucking scheme. Conditions of the data acquisition are optimized to achieve the accurate and efficient measurements. Not only in the steady state of the magnet excitation by constant currents, but also on the way the excite current increases until the magnet quenches the field measurements have been tried, and the results are discussed in this paper on the possibility of the {open_quotes}on-the-fly{close_quotes} measurement using a harmonic coil. Some results on the so-called remnant field of the magnets measured with a Hall probe are also described.

Nakai, Hirotaka; Kabe, Atsushi; Terashima, Akio [National Lab. for High Energy Physics, Tsukuba-shi, Ibaraki-ken (Japan)] [and others

1996-12-31T23:59:59.000Z

370

Structure, dynamical impact and origin of magnetic fields in nearby galaxies in the SKA era  

E-Print Network [OSTI]

Magnetic fields are an important ingredient of the interstellar medium (ISM). Besides their importance for star formation, they govern the transport of cosmic rays, relevant to the launch and regulation of galactic outflows and winds, which in turn are pivotal in shaping the structure of halo magnetic fields. Mapping the small-scale structure of interstellar magnetic fields in many nearby galaxies is crucial to understand the interaction between gas and magnetic fields, in particular how gas flows are affected. Elucidation of the magnetic role in, e.g., triggering star formation, forming and stabilising spiral arms, driving outflows, gas heating by reconnection and magnetising the intergalactic medium has the potential to revolutionise our physical picture of the ISM and galaxy evolution in general. Radio polarisation observations in the very nearest galaxies at high frequencies (>= 3 GHz) and with high spatial resolution (<= 5") hold the key here. The galaxy survey with SKA1 that we propose will also be a...

Beck, Rainer; Colafrancesco, Sergio; Dettmar, Ralf-Jürgen; Ferrière, Katia; Fletcher, Andrew; Heald, George; Heesen, Volker; Horellou, Cathy; Krause, Marita; Lou, Yu-Qing; Mao, Sui Ann; Paladino, Rosita; Schinnerer, Eva; Sokoloff, Dmitry; Stil, Jeroen; Tabatabaei, Fatemeh

2015-01-01T23:59:59.000Z

371

The mitigating effect of magnetic fields on Rayleigh-Taylor unstable inertial confinement fusion plasmas  

SciTech Connect (OSTI)

Rayleigh-Taylor (RT) instabilities at interfaces of disparate mass densities have long been known to generate magnetic fields during inertial confinement fusion implosions. An externally applied magnetic field can also be efficiently amplified by RT instabilities. The focus here is on magnetic field generation and amplification at the gas-ice interface which is RT unstable during the deceleration phase of the implosion. RT instabilities lead to undesirable mix of hot and cold plasmas which enhances thermal energy loss and tends to produce a more massive warm-spot instead of a hot-spot. Two mechanisms are shown here to mitigate the thermal energy loss from the hot-spot. The first mechanism is the reduction of electron thermal conductivity with interface-aligned magnetic fields. This can occur through self-generated magnetic fields via the Biermann battery effect as well as through externally applied magnetic fields that undergo an exponential growth via the stretch-and-fold magnetohydrodynamic dynamo. Self-generated magnetic fields during RT evolution can result in a factor of 2?10 decrease in the electron thermal conductivity at the gas-ice interface, while externally applied magnetic fields that are compressed to 6–1000 T at the onset of deceleration (corresponding to pre-implosion external fields of 0.06–10 T) could result in a factor of 2–500 reduction in electron thermal conductivity at the gas-ice interface. The second mechanism to mitigate thermal energy loss from the hot-spot is to decrease the interface mixing area between the hot and cold plasmas. This is achieved through large external magnetic fields of 1000 T at the onset of deceleration which damp short-wavelength RT modes and long-wavelength Kelvin-Helmholtz modes thus significantly slowing the RT growth and reducing mix.

Srinivasan, Bhuvana; Tang, Xian-Zhu [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2013-05-15T23:59:59.000Z

372

Relationship of sunspot magnetic fields to umbral sizes in return flux theory  

SciTech Connect (OSTI)

The relationship between the relative size of a sunspot umbra and the relative magnitude of the magnetic field at the outer edge of the penumbra is studied. It is found that the sunspot magnetic topology is composed of two magnetic regimes, one consisting of open field lines emerging from the core and extending to infinity, and the second consisting of lines returning to the photosphere. The relative quantity of the return magnetic flux is closely associated with the size of the umbra relative to the penumbra. 31 references.

Osherovich, V.A.; Garcia, H.A.

1989-01-01T23:59:59.000Z

373

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

2008-11-04T23:59:59.000Z

374

Largeamplitude compressive "sawtooth" magnetic field oscillations in the Martian magnetosphere  

E-Print Network [OSTI]

, including a bow shock, a magne- tosheath, an ionosphere, and an extended wake region consisting of two and dynamic and thermal pressure from various ion species in the Martian magne- tosphere differ greatly from order of altitude) a bow shock, a magnetic pileup boundary (MPB) where magnetic pressure increases

California at Berkeley, University of

375

Scripta Materialia 52 (2004) 461-466 Effect of 30 Tesla Magnetic Field on Transformations in a  

E-Print Network [OSTI]

Scripta Materialia 52 (2004) 461-466 Effect of 30 Tesla Magnetic Field on Transformations transforms to ferrite. Thus, a 30 Tesla magnetic field can raise transformation temperatures by ~90°C during

Cambridge, University of

376

The magnetic field of the pre-main sequence Herbig Ae star HD 190073  

E-Print Network [OSTI]

The general context of this paper is the study of magnetic fields in the pre-main sequence intermediate mass Herbig Ae/Be stars. Magnetic fields are likely to play an important role in pre-main sequence evolution at these masses, in particular in controlling the gains and losses of stellar angular momentum. The particular aim of this paper is to announce the detection of a structured magnetic field in the Herbig Ae star HD 190073, and to discuss various scenarii for the geometry of the star, its environment and its magnetic field. We have used the ESPaDOnS spectropolarimeter at CFHT in 2005 and 2006 to obtain high-resolution and signal-to-noise circular polarization spectra which demonstrate unambiguously the presence of a magnetic field in the photosphere of this star. Nine circular polarization spectra were obtained, each one showing a clear Zeeman signature. This signature is suggestive of a magnetic field structured on large scales. The signature, which corresponds to a longitudinal magnetic field of 74+-...

Catala, C; Donati, J F; Wade, G A; Landstreet, J D; Böhm, T; Bouret, J C; Bagnulo, S; Folsom, C; Silvester, J

2006-01-01T23:59:59.000Z

377

The effect of magnetic field on bistability in 1D photonic crystal doped by magnetized plasma and coupled nonlinear defects  

SciTech Connect (OSTI)

In this work, we study the defect mode and bistability behavior of 1-D photonic band gap structure with magnetized plasma and coupled nonlinear defects. The transfer matrix method has been employed to investigate the magnetic field effect on defect mode frequency and bistability threshold. The obtained results show that the frequency of defect mode and bistability threshold can be altered, without changing the structure of the photonic multilayer. Therefore, the bistability behavior of the subjected structure in the presence of magnetized plasma can be utilized in manufacturing wide frequency range devices.

Mehdian, H.; Mohammadzahery, Z.; Hasanbeigi, A. [Department of Physics and Institute for Plasma Research, Kharazmi University, 49 Dr Mofatteh Avenue, Tehran 15614 (Iran, Islamic Republic of)] [Department of Physics and Institute for Plasma Research, Kharazmi University, 49 Dr Mofatteh Avenue, Tehran 15614 (Iran, Islamic Republic of)

2014-01-15T23:59:59.000Z

378

Hydrogen atom in crossed electric and magnetic fields: Phase space topology and torus quantization via periodic orbits  

E-Print Network [OSTI]

A hierarchical ordering is demonstrated for the periodic orbits in a strongly coupled multidimensional Hamiltonian system, namely the hydrogen atom in crossed electric and magnetic fields. It mirrors the hierarchy of broken resonant tori and thereby allows one to characterize the periodic orbits by a set of winding numbers. With this knowledge, we construct the action variables as functions of the frequency ratios and carry out a semiclassical torus quantization. The semiclassical energy levels thus obtained agree well with exact quantum calculations.

Stephan Gekle; Jörg Main; Thomas Bartsch; T. Uzer

2006-10-02T23:59:59.000Z

379

Experimental study of two-dimensional quantum Wigner solid in zero magnetic field  

SciTech Connect (OSTI)

At temperatures T ? 0, strongly interacting two-dimensional (2D) electron systems manifest characteristic insulating behaviors that are key for understanding the nature of the ground state in light of the interplay between disorder and electron-electron interaction. In contrast to the hopping conductance demonstrated in the insulating side of the metal-to-insulator transition, the ultra-high quality 2D systems exhibit nonactivated T-dependence of the conductivity even for dilute carrier concentrations down to 7×10{sup 8} cm{sup ?2}. The apparent metal-to-insulator transition (MIT) occurs for a large r{sub s} value around 40 for which a Wigner Crystalllization is expected. The magnetoresistance for a series of carrier densities in the vicinity of the transition exhibits a characteristic sign change in weak perpendicular magnetic field. Within the Wigner Crystallization regime (with r{sub s} > 40), we report an experimental observation of a characteristic nonlinear threshold behavior from a high-resolution dc dynamical response as an evidence for aWigner crystallization in high-purity GaAs 2D hole systems in zero magnetic field. The system under an increasing current drive exhibits voltage oscillations with negative differential resistance. They confirm the coexistence of a moving crystal along with striped edge states as observed for electrons on helium surfaces. Moreover, the threshold is well below the typical classical levels due to a different pinning and depinning mechanism that is possibly related to quantum processes.

Huang, Jian [Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201 (United States); Pfeiffer, L. N.; West, K. W. [Department of Electrical Engineering, Princeton University, Princeton, NJ 08544 (United States)

2014-03-31T23:59:59.000Z

380

THE INTERPLAY OF TURBULENCE AND MAGNETIC FIELDS IN STAR-FORMING REGIONS: SIMULATIONS AND OBSERVATIONS  

SciTech Connect (OSTI)

We analyze a suite of thin-sheet magnetohydrodynamical simulations based on the formulation of Basu, Ciolek, Dapp, and Wurster. These simulations allow us to examine the observational consequences to a star-forming region of varying the input level of turbulence (between thermal and a Mach number of 4) and the initial magnetic field strength corresponding to a range of mass to flux ratios between subcritical ({mu}{sub 0} = 0.5) and supercritical ({mu}{sub 0} = 10). The input turbulence is allowed to decay over the duration of the simulation. We compare the measured observable quantities with those found from surveying the Perseus molecular cloud. We find that only the most turbulent of simulations (high Mach number and weak magnetic field) have sufficient large-scale velocity dispersion (at {approx}1 pc) to match that observed across extinction regions in Perseus. Generally, the simulated core ({approx}0.02 pc) and line-of-sight velocity dispersions provide a decent match to observations. The motion between the simulated core and its local environment, however, is far too large in simulations with high large-scale velocity dispersion.

Kirk, Helen; Johnstone, Doug [Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 1A1 (Canada); Basu, Shantanu [Department of Physics and Astronomy, University of Western Ontario, 1151 Richmond Street, London, ON, N6A 3K7 (Canada)], E-mail: hkirk@uvastro.phys.uvic.ca

2009-07-10T23:59:59.000Z

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

Polarization operator in the 2+1 dimensional quantum electrodynamics with a nonzero fermion density in a constant uniform magnetic field  

E-Print Network [OSTI]

The polarization operator (tensor) for planar charged fermions in constant uniform magnetic field is calculated in the one-loop approximation of the 2+1 dimensional quantum electrodynamics (QED$_{2+1}$) with a nonzero fermion density. We construct the Green function of the Dirac equation with a constant uniform external magnetic field in the QED$_{2+1}$ at the finite chemical potential, find the imaginary part of this Green function and then obtain the polarization tensor related to the combined contribution from real particles occupying the finite number of energy levels and magnetic field. We expect that some physical effects under consideration seem to be likely to be revealed in a monolayer graphene sample in the presence of external constant uniform magnetic field $B$ perpendicular to it.

V. R. Khalilov; I. V. Mamsurov

2015-03-08T23:59:59.000Z

382

Polarization operator in the 2+1 dimensional quantum electrodynamics with a nonzero fermion density in a constant uniform magnetic field  

E-Print Network [OSTI]

The polarization operator (tensor) for planar charged fermions in constant uniform magnetic field is calculated in the one-loop approximation of the 2+1 dimensional quantum electrodynamics (QED$_{2+1}$) with a nonzero fermion density. We construct the Green function of the Dirac equation with a constant uniform external magnetic field in the QED$_{2+1}$ at the finite chemical potential, find the imaginary part of this Green function and then obtain the polarization tensor related to the combined contribution from real particles occupying the finite number of energy levels and magnetic field. We expect that some physical effects under consideration seem to be likely to be revealed in a monolayer graphene sample in the presence of external constant uniform magnetic field $B$ perpendicular to it.

V. R. Khalilov; I. V. Mamsurov

2015-01-27T23:59:59.000Z

383

Zeeman tomography of magnetic white dwarfs, I. Reconstruction of the field geometry from synthetic spectra  

E-Print Network [OSTI]

We have computed optical Zeeman spectra of magnetic white dwarfs for field strengths between 10 and 200MG and effective temperatures between 8000 and 40000K. They form a database containing 20628 sets of flux and circular polarization spectra. A least-squares optimization code based on an evolutionary strategy can recover relatively complex magnetic field topologies from phase-resolved synthetic Zeeman spectra of rotating magnetic white dwarfs. We consider dipole and quadrupole components which are non-aligned and shifted off-centre. The model geometries include stars with a single high-field spot and with two spots separated by approx. 90 degrees. The accuracy of the recovered field structure increases with the signal-to-noise ratio of the input spectra and is significantly improved if circular polarization spectra are included in addition to flux spectra. We discuss the strategies proposed so far to unravel the field geometries of magnetic white dwarfs.

F. Euchner; S. Jordan; K. Beuermann; B. T. Gaensicke; F. V. Hessmann

2002-05-21T23:59:59.000Z

384

The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Magnetohydrodynamics Simulation Module for the Global Solar Corona  

E-Print Network [OSTI]

Time-dependent three-dimensional magnetohydrodynamics (MHD) simulation modules are implemented at the Joint Science Operation Center (JSOC) of Solar Dynamics Observatory (SDO). The modules regularly produce three-dimensional data of the time-relaxed minimum-energy state of the solar corona using global solar-surface magnetic-field maps created from Helioseismic Magnetic Imager (HMI) full-disk magnetogram data. With the assumption of polytropic gas with specific heat ratio of 1.05, three types of simulation products are currently generated: i) simulation data with medium spatial resolution using the definitive calibrated synoptic map of the magnetic field with a cadence of one Carrington rotation, ii) data with low spatial resolution using the definitive version of the synchronic frame format of the magnetic field, with a cadence of one day, and iii) low-resolution data using near-real-time (NRT) synchronic format of the magnetic field on daily basis. The MHD data available in the JSOC database are three-dimen...

Hayashi, Keiji; Liu, Yang; Bobra, Monica G; Sun, Xudong D; Norton, Aimee A

2015-01-01T23:59:59.000Z

385

Electric Field Control of Ferromagnetism and Magnetic Devices Using Multiferroics  

E-Print Network [OSTI]

4 Electric field control of ferromagnetism: In-plane5 Electric field control of ferromagnetism: out-of-plane6.3.3 Electric field control of spin valve resistance

Heron, John Thomas

2013-01-01T23:59:59.000Z

386

External magnetic field influence on H{sub {alpha}} line in abnormal glow discharge  

SciTech Connect (OSTI)

Influence of the external axial magnetic field on the hydrogen H{sub {alpha}} line profiles in an abnormal glow discharge has been studied. It has been found that the applied magnetic field predominantly increases the intensity of central component of the characteristic excessively broadened H{sub {alpha}} profile. Magnetic filed causes helical motion of electrons along the electric field lines and prolongs their trajectories increasing the number of collisions with matrix gas. This explains the increase of the central component of H{sub {alpha}} profile and can be regarded as an experimental proof for the main contribution of electron excitation to that part of the profile.

Obradovic, B.M.; Dojcinovic, I.P.; Kuraica, M.M.; Puric, J. [Faculty of Physics, University of Belgrade, P.O. Box 368, 11001 Belgrade (Serbia and Montenegro) and Center for Science and Development of Technology, Obilicev Venac 26, 11001 Belgrade (Serbia and Montenegro)

2006-04-03T23:59:59.000Z

387

Magnetic Field Effect on Charmonium Production in High Energy Nuclear Collisions  

E-Print Network [OSTI]

It is important to understand the strong external magnetic field generated at the very beginning of high energy nuclear collisions. We study the effect of the magnetic field on the charmonium yield and anisotropic distribution in Pb+Pb collisions at the LHC energy. The time dependent Schr\\"odinger equation is employed to describe the motion of $c\\bar{c}$ pairs. We compare our model prediction of non- collective anisotropic parameter $v_2$ of $J/\\psi$s with CMS data at high transverse momentum. This is the first attempt to measure the magnetic field in high energy nuclear collisions.

Guo, Xingyu; Xu, Nu; Xu, Zhe; Zhuang, Pengfei

2015-01-01T23:59:59.000Z

388

Efficiency enhancement of anomalous-Doppler electron cyclotron masers with tapered magnetic field  

SciTech Connect (OSTI)

The efficiency of slow-wave electron cyclotron masers (ECM) is usually low, thus limiting the practical applications. Here, a method of tapered magnetic field is introduced for the efficiency enhancement of the slow-wave ECM. The numerical calculations show that the tapered magnetic-field method can enhance the efficiency of slow-wave ECM significantly. The effect of beam electron velocity spread on the efficiency has also been studied. Although the velocity spread reduces the efficiency, a great enhancement of efficiency can still be obtained by the tapered magnetic field method.

Xie, Chao-Ran; Hou, Zhi-Ling [Beijing Key Laboratory of Harmful Chemicals Analysis and School of Science, Beijing University of Chemical Technology, Beijing 100029 (China)] [Beijing Key Laboratory of Harmful Chemicals Analysis and School of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Kong, Ling-Bao, E-mail: konglingbao@gmail.com, E-mail: pkliu@pku.edu.cn [School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China) [School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China); Beijing Key Laboratory of Harmful Chemicals Analysis and School of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Liu, Pu-Kun, E-mail: konglingbao@gmail.com, E-mail: pkliu@pku.edu.cn; Du, Chao-Hai [School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China)] [School of Electronics Engineering and Computer Science, Peking University, Beijing 100871 (China); Jin, Hai-Bo [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)] [School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081 (China)

2014-02-15T23:59:59.000Z

389

The Energy Eigenvalues of the Two Dimensional Hydrogen Atom in a Magnetic Field  

E-Print Network [OSTI]

In this paper, the energy eigenvalues of the two dimensional hydrogen atom are presented for the arbitrary Larmor frequencies by using the asymptotic iteration method. We first show the energy eigenvalues for the no magnetic field case analytically, and then we obtain the energy eigenvalues for the strong and weak magnetic field cases within an iterative approach for $n=2-10$ and $m=0-1$ states for several different arbitrary Larmor frequencies. The effect of the magnetic field on the energy eigenvalues is determined precisely. The results are in excellent agreement with the findings of the other methods and our method works for the cases where the others fail.

A. Soylu; O. Bayrak; I. Boztosun

2007-03-13T23:59:59.000Z

390

Wave breaking phenomenon of lower-hybrid oscillations induced by a background inhomogeneous magnetic field  

SciTech Connect (OSTI)

In a fluid description, we study space-time evolution of lower hybrid modes in a cold quasi-neutral homogeneous plasma in presence of a background inhomogeneous magnetic field. Within a linear analysis, a dispersion relation with inhomogeneous magnetic field shows 'phase mixing' of such oscillations. A manifestation of 'phase mixing' is shown in 'mode coupling.' By using Lagrangian variables, an exact solution is presented in parametric form of this nonlinear time dependent problem. It is demonstrated that initially excited lower hybrid modes always break via phase mixing phenomenon in presence of an inhomogeneous magnetic field. Breaking of such oscillations is revealed by the appearance of spikes in the plasma density profile.

Maity, Chandan; Chakrabarti, Nikhil [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Sengupta, Sudip [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

2012-10-15T23:59:59.000Z

391

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

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

Cyrus Field, who had made his fortune in paper manufacturing. Transatlantic Telegraph Cable Field knew little about the telegraph. But after meeting with owners of the...

392

Wave Turbulence on the Surface of a Ferrofluid in a Magnetic Field Francois Boyer and Eric Falcon*  

E-Print Network [OSTI]

Wave Turbulence on the Surface of a Ferrofluid in a Magnetic Field Franc¸ois Boyer and Eric Falcon the observation of wave turbulence on the surface of a ferrofluid mechanically forced and submitted to a static normal magnetic field. We show that magnetic surface waves arise only above a critical field. The power

Falcon, Eric

393

Wave turbulence on the surface of a ferrofluid submitted to a magnetic field Francois Boyer and Eric Falcon  

E-Print Network [OSTI]

Wave turbulence on the surface of a ferrofluid submitted to a magnetic field Fran¸cois Boyer the observation of wave turbulence on the surface of a ferrofluid mechanically forced and submitted to a static normal magnetic field. We show that magnetic surface waves arise only above a critical field. The power

Paris-Sud XI, Université de

394

Propagation of shear Alven waves in two-ion species plasmas confined by a nonuniform magnetic field  

E-Print Network [OSTI]

Propagation of shear Alven waves in two-ion species plasmas confined by a nonuniform magnetic field for waves originally propagating along the magnetic field direction. Calculations are performed for waves propagating across the confinement magnetic field, typically the compressional or fast Alfven wave

California at Los Angles, University of

395

Magnetism in pre-MS intermediate-mass stars and the fossil field hypothesis  

E-Print Network [OSTI]

Today, one of the greatest challenges concerning the Ap/Bp stars is to understand the origin of their slow rotation and their magnetic fields. The favoured hypothesis for the latter is the fossil field, which implies that the magnetic fields subsist throughout the different evolutionary phases, and in particular during the pre-main sequence phase. The existence of magnetic fields at the pre-main sequence phase is also required to explain the slow rotation of Ap/Bp stars. However, until recently, essentially no information was available about the magnetic properties of intermediate-mass pre-main sequence stars, the so-called Herbig Ae/Be stars. The new high-resolution spectropolarimeter ESPaDOnS, installed in 2005 at the Canada-France-Hawaii telescope, provided the capability necessary to perform surveys of the Herbig Ae/Be stars in order to investigate their magnetism and rotation. These investigations have resulted in the detection and/or confirmation of magnetic fields in 8 Herbig Ae/Be stars, ranging in mass from 2 to nearly 15 solar masses. In this contribution I will present the results of our survey, as well as their implications for the origin and evolution of the magnetic fields and rotation.

E. Alecian; G. A. Wade; C. Catala; C. Folsom; J. Grunhut; J. -F. Donati; P. Petit; S. Bagnulo; S. C. Marsden; J. Ramirez; J. D. Landstreet; T. Boehm; J. -C. Bouret; J. Silvester

2007-12-03T23:59:59.000Z

396

Field representation of a watt balance magnet by partial profile measurements  

E-Print Network [OSTI]

Permanent magnets with high-permeability yokes have been widely used in watt balances for supplying a robust and strong magnetic field at the coil position. Subjected to the mechanical realization, only several $B_r(z)$ (radial magnetic field along the vertical direction) profiles can be measured by coils for field characterization. In this article, we present an algorithm that can construct the global magnetic field of the air gap based on $N(N\\geq1)$ additional measurements of $B_r(z)$ profiles. The proposed algorithm is realized by polynomially estimating the $B_z(r)$ function with analysis of basic relations between two magnetic components in air gap, i.e., $B_r(r,z)$ and $B_z(r,z)$, following the Maxwell's equations. The algorithm, verified by FEM simulations, can characterize the three-dimensional contribution of the magnetic field for a watt balance magnet with acceptable accuracy, which would supply basic field parameters for alignment and misalignment corrections.

Li, Shisong; Zhao, Wei; Huang, Songling

2015-01-01T23:59:59.000Z

397

The crucial role of surface magnetic fields for the solar dynamo  

E-Print Network [OSTI]

Sunspots and the plethora of other phenomena occuring in the course of the 11-year cycle of solar activity are a consequence of the emergence of magnetic flux at the solar surface. The observed orientations of bipolar sunspot groups imply that they originate from toroidal (azimuthally orientated) magnetic flux in the convective envelope of the Sun. We show that the net toroidal magnetic flux generated by differential rotation within a hemisphere of the convection zone is determined by the emerged magnetic flux at the solar surface and thus can be calculated from the observed magnetic field distribution. The main source of the toroidal flux is the roughly dipolar surface magnetic field at the polar caps, which peaks around the minima of the activity cycle.

Cameron, Robert

2015-01-01T23:59:59.000Z

398

Nonideal evolution of nonaxisymmetric, force-free magnetic fields in a magnetar  

E-Print Network [OSTI]

Recent numerical magnetohydrodynamic calculations by Braithwaite and collaborators support the `fossil field' hypothesis regarding the origin of magnetic fields in compact stars and suggest that the resistive evolution of the fossil field can explain the reorganisation and decay of magnetar magnetic fields. Here, these findings are modelled analytically by allowing the stellar magnetic field to relax through a quasistatic sequence of nonaxisymmetric, force-free states, by analogy with spheromak relaxation experiments, starting from a random field. Under the hypothesis that the force-free modes approach energy equipartition in the absence of resistivity, the output of the numerical calculations is semiquantitatively recovered: the field settles down to a linked poloidal-toroidal configuration, which inflates and becomes more toroidal as time passes. A qualitatively similar (but not identical) end state is reached if the magnetic field evolves by exchanging helicity between small and large scales according to an $\\alpha$-dynamo-like, mean-field mechanism, arising from the fluctuating electromotive force produced by the initial random field. The impossibility of matching a force-free internal field to a potential exterior field is discussed in the magnetar context.

Alpha Mastrano; Andrew Melatos

2008-04-25T23:59:59.000Z

399

National High Magnetic Field Laboratory - About This Site  

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

About This Site In 2006, the Magnet Lab Public Affairs Group and Web team redesigned this site in an effort both to better showcase our existing content as well as provide a...

400

National High Magnetic Field Laboratory - Publications of the...  

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

Morika, Japan, October 20-24 (2003) 7 Walsh, R.P. and Toplosky, V.J., Axial Reverse-Cycle Fatigue Tests of High Strength Pulse Magnet Conductors at 77 K, CECICMC 2003,...

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

Negative index of refraction in a four-level system with magnetoelectric cross coupling and local field corrections  

SciTech Connect (OSTI)

This research focuses on a coherently driven four-level atomic medium with the aim of inducing a negative index of refraction while taking into consideration local field corrections as well as magnetoelectric cross coupling (i.e.,chirality) within the material's response functions. Two control fields are used to render the medium transparent for a probe field which simultaneously couples to an electric and a magnetic dipole transition, thus allowing one to test the permittivity and permeability of the material at the same time. Numerical simulations show that a negative index of refraction with low absorption can be obtained for a range of probe detunings while depending on number density and the ratio between the intensities of the control fields.

Bello, F. [Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain)

2011-07-15T23:59:59.000Z

402

Stationary components of HeI in strong magnetic fields - a tool to identify magnetic DB white dwarfs  

E-Print Network [OSTI]

In only three of the 61 known magnetic white dwarfs helium has been identified unambiguously while about 20% of all non-magnetic stars of this class are known to contain HeI or HeII. Until recently, data for HeI data were available only for magnetic fields below 20MG. This changed with the publication of extensive data by the group in Heidelberg. The corresponding calculations have now been completed for the energetically lowest five states of singlet and triplet symmetry for the subspaces with |m| <= 3; selected calculations have been performed for even higher excitations. In strongly magnetized white dwarfs only line components are visible whose wavelengths vary slowly with respect to the magnetic field, particularly stationary components which have a wavelength minimum or maximum in the range of the magnetic fields strengths on the stellar surface. In view of the many ongoing surveys finding white dwarfs we want to provide the astronomical community with a tool to identify helium in white dwarfs for fields up to 5.3GG. To this end we present all calculated helium line components whose wavelengths in the UV, optical, and near IR vary slowly enough with respect to the field strength to produce visible absorption features. We also list all stationary line components in this spectral range. Finally, we find series of minima and maxima which occur as a result of series of extremal transitions to increasingly higher excitations. We estimated the limits for 8 series which can possibly give rise to additional absorption in white dwarf spectra; one strong absorption feature in GD229 which is yet unexplained by stationary components is very close to two estimated series limits.

S. Jordan; P. Schmelcher; W. Becken

2001-06-29T23:59:59.000Z

403

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

404

Magnetic anisotropy in a permalloy microgrid fabricated by near-field optical lithography  

SciTech Connect (OSTI)

We report the fabrication and magnetic properties of permalloy microgrids prepared by near-field optical lithography and characterized using high-sensitivity magneto-optical Kerr effect techniques. A fourfold magnetic anisotropy induced by the grid architecture is identified. {copyright} 2001 American Institute of Physics.

Li, S. P.; Lebib, A.; Peyrade, D.; Natali, M.; Chen, Y.; Lew, W. S.; Bland, J. A. C.

2001-07-01T23:59:59.000Z

405

Three-dimensional Josephson junction networks with coupling inhomogeneities in magnetic fields  

E-Print Network [OSTI]

Three-dimensional Josephson junction networks with coupling inhomogeneities in magnetic fields A on the static magnetic response of a three-dimensional 8 · 8 · 8 network of Josephson junctions is studied of one-dimensional and two-dimensional Josephson junction networks (1D, 2D-JJNs) has been extensively

Di Matteo, Tiziana

406

Classification of instability modes in a model of aluminium reduction cells with a uniform magnetic field  

E-Print Network [OSTI]

(sodium aluminium fluoride) by an electric current of 350-500kA, which passes vertically down fromClassification of instability modes in a model of aluminium reduction cells with a uniform magnetic reduction cells in the presence of a uniform, vertical, background magnetic field is presented

407

The magnetic field and wind confinement of b Cephei: new clues for interpreting the Be phenomenon?  

E-Print Network [OSTI]

The magnetic field and wind confinement of b Cephei: new clues for interpreting the Be phenomenon and of the associated magnetically confined wind and circumstellar environment. A re- examination of the fundamental with an inclination of the rotation axis of about 608. Using two different modelling strategies, we obtain

Donati, Jean-François

408

Scaling of forced magnetic reconnection in the Hall-magnetohydrodynamical Taylor problem with arbitrary guide field  

E-Print Network [OSTI]

. © 2004 American Institute of Physics. DOI: 10.1063/1.1768956 I. INTRODUCTION Magnetic reconnection experiments,1 the solar corona,2 and the Earth's magnetotail.3 The reconnection process gives rise to a change equilibrium with a central magnetic-field resonance is subject to a sud- denly imposed, small amplitude

Fitzpatrick, Richard

409

Magnetic Field Generation in Planets and Satellites by Natural Nuclear Fission Reactors  

E-Print Network [OSTI]

One of the most fundamental problems in physics has been to understand the nature of the mechanism that generates the geomagnetic field and the magnetic fields of other planets and satellites. For decades, the dynamo mechanism, thought to be responsible for generating the geomagnetic field and other planetary magnetic fields, has been ascribed to convection in each planet's iron-alloy core. Recently, I described the problems inherent in Earth-core convection and proposed instead that the geomagnetic field is produced by a dynamo mechanism involving convection, not in the fluid core, but in the electrically conductive, fluid, fission-product sub-shell of a natural nuclear fission reactor at the center of the Earth, called the georeactor. Here I set forth in detail the commonality in the Solar System of the matter like that of the inside of the Earth, which is my basis for generalizing the concept of planetary magnetic field generation by natural planetocentric nuclear fission reactors.

J. Marvin Herndon

2007-09-27T23:59:59.000Z

410

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

411

Ferrofluid spin-up flows from uniform and non-uniform rotating magnetic fields  

E-Print Network [OSTI]

When ferrofluid in a cylindrical container is subjected to a rotating azimuthally directed magnetic field, the fluid "spins up" into an almost rigid-body rotation where ferrofluid nanoparticles have both a linear and an ...

Khushrushahi, Shahriar Rohinton

2010-01-01T23:59:59.000Z

412

Symmetry breaking for ratchet transport in presence of interactions and magnetic field  

E-Print Network [OSTI]

We study the microwave induced ratchet transport of two-dimensional electrons on an oriented semidisk Galton board. The magnetic field symmetries of ratchet transport are analyzed in presence of electron-electron interactions. Our results show that a magnetic field asymmetric ratchet current can appear due to two contributions, a Hall drift of the rectified current that depends only weakly on electron-electron interactions and a breaking of the time reversal symmetry due to the combined effects of interactions and magnetic field. In the latter case, the asymmetry between positive and negative magnetic fields vanishes in the weak interaction limit. We also discuss the recent experimental results on ratchet transport in asymmetric nanostructures.

Leonardo Ermann; Alexei D. Chepelianskii; Dima L. Shepelyansky

2012-11-19T23:59:59.000Z

413

Stability of Relativistic Matter with Magnetic Fields for Nuclear Charges up to the Critical Value  

E-Print Network [OSTI]

We give a proof of stability of relativistic matter with magnetic fields all the way up to the critical value of the nuclear charge $Z\\alpha=2/\\pi$.

Rupert L. Frank; Elliott H. Lieb; Robert Seiringer

2006-10-24T23:59:59.000Z

414

Effects of demagnetizing factors on transient motion of ferrofluid in a uniform rotating magnetic field  

E-Print Network [OSTI]

The mechanisms that lead to bulk flow within a ferrofluid-filled container subjected to a rotating uniform magnetic field are experimentally studied. There are two prevailing theories: spin diffusion theory and flow due ...

Snively, Michael John

2011-01-01T23:59:59.000Z

415

TRANSPORT EFFECTS IN THE EVOLUTION OF THE GLOBAL SOLAR MAGNETIC FIELD  

E-Print Network [OSTI]

Astrofâ?? �sica de Canarias, La Laguna, Tenerife, E­38200 Spain G. SZAK â?? ALY EË? otvË? os University of tracers of the magnetic field such as quiescent filaments, polar faculae, or the coronal green line

Petrovay, Kristóf

416

Ferrohydrodynamic flows in uniform and non-uniform rotating magnetic fields  

E-Print Network [OSTI]

Ferrofluids are conventionally used in such DC magnetic field applications as rotary and exclusion seals, stepper motor dampers, and heat transfer fluids. Recent research demonstrates ferrofluid use in alternating and ...

He, Xiaowei, Ph. D. Massachusetts Institute of Technology

2006-01-01T23:59:59.000Z

417

A simple model for the distribution of quiet Sun magnetic field strengths  

E-Print Network [OSTI]

We derive a first order linear differential equation describing the shape of the probability density function of magnetic field strengths in the quiet Sun (PDF). The modeling is very schematic. It considers convective motions which continuously supply and withdraw magnetic structures. In addition, a magnetic amplification mechanism increases the field strength up to a threshold that cannot be exceeded. These three basic ingredients provide PDFs in good agreement with the PDFs produced by realistic numerical simulations of magneto convection, as well as with quiet Sun PDFs inferred from observations. In particular, the distribution is approximately lognormal, and it produces an excess of magnetic fields (i.e., a 'hump' in the distribution) right before the maximum field strength. The success of this simple model may indicate that only a few basic ingredients shape the quiet Sun PDF. Our approach provides a concise parametric representation of the PDF, as required to develop automatic methods of diagnostics.

J. Sanchez Almeida

2006-12-11T23:59:59.000Z

418

A two-phase spherical electric machine for generating rotating uniform magnetic fields  

E-Print Network [OSTI]

This thesis describes the design and construction of a novel two-phase spherical electric machine that generates rotating uniform magnetic fields, known as a fluxball machine. Alternative methods for producing uniform ...

Lawler, Clinton T. (Clinton Thomas)

2007-01-01T23:59:59.000Z

419

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

420

Simulation of adiabatic thermal beams in a periodic solenoidal magnetic focusing field  

E-Print Network [OSTI]

Self-consistent particle-in-cell simulations are performed to verify earlier theoretical predictions of adiabatic thermal beams in a periodic solenoidal magnetic focusing field [ K.?R. Samokhvalova, J. Zhou and C. Chen ...

Barton, T. J.

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

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

422

Attempts to elicit an evoked potential in the pigeon using a magnetic field stimulus  

E-Print Network [OSTI]

ATTEMPTS TO ELICIT AN EVOKED POTENTIAL IN THE PIGEON USING A MAGNETIC FIELD STIMULUS A Thesis by WILLIAM ROBERT RANDOLPH Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE December 19B4 Major Subject: Bioengineering ATTEMPTS TO ELICIT AN EVOKED POTENTIAL IN THE PIGEON USING A MAGNETIC FIELD STIMULUS A Thesis by WILLIAM ROBERT RANDOLPH ( Approved as to style and content by: Jon F. Hunter (Chairma...

Randolph, William Robert

1984-01-01T23:59:59.000Z

423

Double active shielded magnetic field gradient design with minimum inductance method  

E-Print Network [OSTI]

DOUBLE ACTIVE SHIELDED MAGNETIC FIELD GRADIENT DESIGN WITH MINIMUM INDUCTANCE METHOD A Thesis by XU WANG Submitted to the Oflice of Graduate Studies of Texas ASM University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE May 1992 Major Subject: Physics DOUBLE ACTIVE SHIELDED MAGNETIC FIELD GRADIENT DESIGN WITH MINIMUM INDUCTANCE METHOD A Thesis by XU WANG Approved as to style and content by: F. R. Huson (Chair of Committee) Steve Wry (Member) Edward...

Wang, Xu

1992-01-01T23:59:59.000Z

424

Measuring stellar magnetic fields with the low resolution spectropolarimeter of the William Herschel Telescope  

E-Print Network [OSTI]

Despite the influence of magnetic fields on the structure and evolution of stars is largely demonstrated from the theoretical point of view, their observational evidence in non-degenerated stars is still rather scanty and mainly circumscribed to bright objects (V 600, show an internal error of <50 G selecting the whole interval and <200 G within a Balmer line. Ripples in the Stokes V spectra of HD3360 result in an instrumental positive magnetic field certainly not larger than 80 G.

F. Leone

2007-09-13T23:59:59.000Z

425

From constant to non-degenerately vanishing magnetic fields in superconductivity  

E-Print Network [OSTI]

We explore the relationship between two reference functions arising in the analysis of the Ginzburg-Landau functional. The first function describes the distribution of superconductivity in a type II superconductor subjected to a constant magnetic field. The second function describes the distribution of superconductivity in a type II superconductor submitted to a variable magnetic field that vanishes non-degenerately along a smooth curve.

Bernard Helffer; Ayman Kachmar

2015-03-30T23:59:59.000Z

426

Kaon Condensation in a Neutron Star under Strong Magnetic Fields by Using the Modified Quark-meson Coupling Model  

E-Print Network [OSTI]

We have considered the antikaon condensation in a neutron star in the presence of strong magnetic fields by using the modified quark-meson coupling (MQMC) model. The structure of the neutron star is investigated with various magnetic fields and different kaon optical potentials, and the effects of the magnetic fields for kaon condensation is discussed. When employing strong magnetic fields inside a neutron star with hyperons and kaon condensation, the magnetic fields can cause the equation of state to be stiff; thus, a large maximum mass of the neutron star can be obtained.

C. Y. Ryu; S. W. Hong

2011-08-27T23:59:59.000Z

427

Color-Superconducting Gap in the Presence of a Magnetic Field  

E-Print Network [OSTI]

We explore the effects of an external magnetic field in the structure and magnitude of the diquark condensate in a three massless quark flavor color superconductor. It is shown that the long-range component $\\widetilde{B}$ of the external magnetic field that penetrates the color-flavor locked (CFL) phase modifies its gap structure, producing a new phase of lower symmetry. Our analysis is performed within an NJL effective field theory with four-fermion interactions, inspired by one-gluon exchange. Using Ritus' method, we compute the quark propagators in the presence of a background magnetic field, and derive the gap equations for arbitrary values of the field. An analytical solution is found for strong magnetic fields. A main outcome of our study is that the $\\widetilde{B}$ field tends to strengthen the gaps that get contributions from pairs of $\\widetilde{Q}$-charged quarks. These gaps are enhanced through the field-dependent density of states of the $\\widetilde{Q}$-charged quarks on the Fermi surface. Our considerations are relevant for the study of highly magnetized compact stars.

Efrain J. Ferrer; Vivian de la Incera; Cristina Manuel

2006-05-17T23:59:59.000Z

428

High-field magnets using high-critical-temperature superconducting thin films  

DOE Patents [OSTI]

High-field magnets fabricated from high-critical-temperature superconducting ceramic (HTSC) thin films which can generate fields greater than 4 Tesla are disclosed. The high-field magnets are made of stackable disk-shaped substrates coated with HTSC thin films, and involves maximizing the critical current density, superconducting film thickness, number of superconducting layers per substrate, substrate diameter, and number of substrates while minimizing substrate thickness. The HTSC thin films are deposited on one or both sides of the substrates in a spiral configuration with variable line widths to increase the field. 4 figures.

Mitlitsky, F.; Hoard, R.W.

1994-05-10T23:59:59.000Z

429

High-field magnets using high-critical-temperature superconducting thin films  

DOE Patents [OSTI]

High-field magnets fabricated from high-critical-temperature superconducting ceramic (HTSC) thin films which can generate fields greater than 4 Tesla. The high-field magnets are made of stackable disk-shaped substrates coated with HTSC thin films, and involves maximizing the critical current density, superconducting film thickness, number of superconducting layers per substrate, substrate diameter, and number of substrates while minimizing substrate thickness. The HTSC thin films are deposited on one or both sides of the substrates in a spiral configuration with variable line widths to increase the field.

Mitlitsky, Fred (Livermore, CA); Hoard, Ronald W. (Livermore, CA)

1994-01-01T23:59:59.000Z

430

Onset and saturation of ion heating by odd-parity rotating-magnetic-fields in a field-reversed configuration  

E-Print Network [OSTI]

Heating of figure-8 ions by odd-parity rotating magnetic fields ($RMF_o$) applied to an elongated field-reversed configuration (FRC) is investigated. The largest energy gain occurs at resonances ($s \\equiv \\omega_R/ \\omega$) of the $RMF_o$ frequency, $\\omega_R$, with the figure-8 orbital frequency, $\\omega$, and is proportional to $s^2$ for $s-even$ resonances and to $s$ for $s-odd$ resonances. The threshold for the transition from regular to stochastic orbits explains both the onset and saturation of heating. The FRC magnetic geometry lowers the threshold for heating below that in the tokamak by an order of magnitude.

A. S. Landsman; S. A. Cohen; A. H. Glasser

2011-01-25T23:59:59.000Z

431

Multiple ion species plasmas with thermal ions in an oblique magnetic field  

SciTech Connect (OSTI)

Using a three-fluid model, the combined effects of an oblique magnetic field and finite temperature of positive ion species on the characteristics of the sheath region of multi-component plasmas are investigated numerically. It is assumed that the ion species are singly charged and have different masses. In the presence of an external magnetic field, it is shown that the density distribution of positive ion species (especially the lighter ion species) begins to fluctuate and does not decrease monotonically towards the wall. Also, it is shown that by increasing the magnetic field, the amplitude of fluctuation increases and its position moves towards the sheath edge. Moreover, it is illustrated that the presence of the magnetic field affects the sheath width and by increasing the magnetic field, the sheath width decreases. In addition, the results show that in the presence of the magnetic field, the increase of temperature of positive ion species has an infinitesimal effect on the sheath width and density distribution of positive ion species.

Hatami, M. M. [Physics Department of K N Toosi University of Technology, 15418-49611 Tehran (Iran, Islamic Republic of)] [Physics Department of K N Toosi University of Technology, 15418-49611 Tehran (Iran, Islamic Republic of)

2013-08-15T23:59:59.000Z

432

The effect of magnetic field on copper in various corrosive medium  

SciTech Connect (OSTI)

The effect of applied magnetic field on the corrosion behaviour of copper within various corrosive medium is investigated. The copper coupon is immersed in 0.5 M HCl, 0.5 M NaCl and 0.5 M NaOH with or without applying up to 40 mT magnetic fields for 24 hours. The weight loss of copper coupon in HCl increased up to 96.56% with applied magnetic fields. However, in NaOH medium, only 33.33% more weight loss was observed and no difference were observed for coupons in NaCl when magnetic field is applied. This observation indicates that corrosion behaviour in HCl and NaOH is controlled by mass transport that can be influenced by the induced magneto hydrodynamics effect when magnetic field is applied. There was no change in weight loss of copper in NaCl when magnetic field is applied because the corrosion mechanism of copper in NaCl is governed by electron charge transfer.

Ang, L. Y.; Othman, N. K.; Jalar, A. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Ismail, I. [Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

2014-09-03T23:59:59.000Z

433

Magnetic Vortex Core Reversal by Low-Field Excitations  

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

AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: VegetationEquipment Surfaces and InterfacesAdministration -Lowell L.FallU .Magnetic Vortex CoreMagnetic

434

Heat treatment and Magnetic Field Procedure A 32mm diameter bore resistive magnet with a 33T maximum field strength at the National High  

E-Print Network [OSTI]

-heating coil set-up has been designed to heat and cool the specimen while inside the bore of the magnetC/s to the annealing temperature. A 3-minute hold at 1000ºC was performed to fully transform the initial microstructure for the field to reach 30T. Specimen cooling was controlled via feedback loop such that by decreasing power

Cambridge, University of

435

Reduced intermittency in the magnetic turbulence of reversed field pinch plasmas  

SciTech Connect (OSTI)

The statistical temporal properties of broadband magnetic turbulence in the edge of reversed field pinch (RFP) plasmas are significantly altered when global magnetohydrodynamic tearing modes and magnetic relaxation are reduced. Standard RFP plasmas, having relatively large tearing fluctuations, exhibit broadband intermittent bursts of magnetic fluctuations in the bandwidth f<1.5 MHz. When the global tearing is reduced via parallel current drive in the edge region, the magnetic turbulence is much less intermittent and has statistical behavior typical of self-similar turbulence (like that expected in self-organized criticality systems). A connection between intermittency and long wavelength plasma instabilities is therefore implied.

Marrelli, L.; Frassinetti, L.; Martin, P.; Craig, D.; Sarff, J.S. [Consorzio RFX, Associazione EURATOM-ENEA sulla Fusione, Corso Stati Uniti, 4 35127 Padova (Italy); Consorzio RFX, Associazione EURATOM-ENEA sulla Fusione, Corso Stati Uniti, 4 35127 Padova (Italy) and Dipartimento di Fisica G. Galilei, Universitat di Padova, 35131 Padova (Italy); Department of Physics and Center for Magnetic Self-Organization in Astrophysical and Laboratory Plasmas, University of Wisconsin, 1150 University Avenue, Madison, Wisconsin 53706 (United States)

2005-03-01T23:59:59.000Z

436

Coexisting Superconductivity and Magnetism in UCoGe Gregory S. Boebinger, National High Magnetic Field Laboratory  

E-Print Network [OSTI]

Coexisting Superconductivity and Magnetism in UCoGe Gregory S. Boebinger, National High Magnetic focused on the coexistence of superconductivity and ferromagnetism, including UGe2, URhGe, and UCoGe. In these materials, superconductivity develops below the ferromagnetic Curie temperature TC without destroying

Weston, Ken

437

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

438

Detection of pico-Tesla magnetic fields using magneto-electric sensors at room temperature  

SciTech Connect (OSTI)

The measurement of low-frequency (10{sup -2}-10{sup 3} Hz) minute magnetic field variations (10{sup -12} Tesla) at room temperature in a passive mode of operation would be critically enabling for deployable neurological signal interfacing and magnetic anomaly detection applications. However, there is presently no magnetic field sensor capable of meeting all of these requirements. Here, we present new bimorph and push-pull magneto-electric laminate composites, which incorporate a charge compensation mechanism (or bridge) that dramatically enhances noise rejection, enabling achievement of such requirements.

Zhai Junyi; Xing Zengping; Dong Shuxiang; Li Jiefang; Viehland, D. [Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)

2006-02-06T23:59:59.000Z

439

Scanning localized magnetic fields in a microfluidic device with a single nitrogen vacancy center  

E-Print Network [OSTI]

Nitrogen vacancy (NV) color centers in diamond have emerged as highly versatile optical emitters that exhibit room temperature spin properties. These characteristics make NV centers ideal for magnetometry, which plays an important role in chemical and biological sensing applications. The integration of NV magnetometers with microfluidic systems could enable the study of isolated chemical and biological samples in a fluid environment with high spatial resolution. Here we demonstrate a method to perform localized magnetometry with nanometer spatial precision using a single NV center in a microfluidic device. We manipulate a magnetic particle within a liquid environment using a combination of planar microfluidic flow control and vertical magnetic actuation to achieve 3-dimensional manipulation. A diamond nanocrystal containing a single NV center is deposited in the microfluidic channels and acts as a local magnetic field probe. We map out the magnetic field distribution of the magnetic particle by varying its position relative to the diamond nanocrystal and performing optically resolved electron spin resonance (ESR) measurements. We control the magnetic particle position with a 48 nm precision and attain a magnetic field sensitivity of 17.5 microTesla/Hz^1/2. These results open up the possibility for studying local magnetic properties of biological and chemical systems with high sensitivity in an integrated microfluidic platform.

Kangmook Lim; Chad Ropp; Benjamin Shapiro; Jacob M. Taylor; Edo Waks

2014-08-01T23:59:59.000Z

440

Terahertz Spectroscopy of Spin Waves in Multiferroic BiFeO3 in High Magnetic Fields  

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

We have studied the magnetic field dependence of far-infrared active magnetic modes in a single ferroelectric domain BiFeO3 crystal at low temperature. The modes soften close to the critical field of 18.8 T along the [001] (pseudocubic) axis, where the cycloidal structure changes to the homogeneous canted antiferromagnetic state and a new strong mode with linear field dependence appears that persists at least up to 31 T. A microscopic model that includes two Dzyaloshinskii-Moriya interactions and easy-axis anisotropy describes closely both the zero-field spectroscopic modes as well as their splitting and evolution in a magnetic field. The good agreement of theory with experiment suggests that the proposed model provides the foundation for future technological applications of this multiferroic material.

Nagel, U.; Fishman, Randy S.; Katuwal, T.; Engelkamp, H.; Talbayev, D.; Yi, Hee Taek; Cheong, S.-W.; Rõõm, T.

2013-06-01T23:59:59.000Z

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

A magnetically shielded room with ultra low residual field and gradient  

SciTech Connect (OSTI)

A versatile and portable magnetically shielded room with a field of (700 ± 200) pT within a central volume of 1 m × 1 m × 1 m and a field gradient less than 300 pT/m, achieved without any external field stabilization or compensation, is described. This performance represents more than a hundredfold improvement of the state of the art for a two-layer magnetic shield and provides an environment suitable for a next generation of precision experiments in fundamental physics at low energies; in particular, searches for electric dipole moments of fundamental systems and tests of Lorentz-invariance based on spin-precession experiments. Studies of the residual fields and their sources enable improved design of future ultra-low gradient environments and experimental apparatus. This has implications for developments of magnetometry beyond the femto-Tesla scale in, for example, biomagnetism, geosciences, and security applications and in general low-field nuclear magnetic resonance (NMR) measurements.

Altarev, I.; Chesnevskaya, S.; Gutsmiedl, E.; Kuchler, F.; Lins, T.; Marino, M.; McAndrew, J.; Niessen, B.; Paul, S.; Petzoldt, G.; Singh, J.; Stoepler, R.; Stuiber, S.; Sturm, M.; Taubenheim, B. [Physikdepartment, Technische Universität München, D-85748 Garching (Germany); Babcock, E. [Jülich Center for Neutron Science, Lichtenbergstrasse 1, D-85748 Garching (Germany); Beck, D.; Sharma, S. [Physics Department, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Burghoff, M.; Fan, I. [Physikalisch-Technische Bundesanstalt Berlin, D-10587 Berlin (Germany); and others

2014-07-15T23:59:59.000Z

442

Influence of magnet size on magnetically engineered field-induced superconductivity W. Gillijns,1,* M. V. Milosevi,2,3 A. V. Silhanek,1 V. V. Moshchalkov,1, and F. M. Peeters3,  

E-Print Network [OSTI]

Influence of magnet size on magnetically engineered field-induced superconductivity W. Gillijns,1-Institute for Nanoscale Physics and Chemistry, Nanoscale Superconductivity and Magnetism and Pulsed Fields Group, K of Co/Pt magnetic disks with out-of-plane magnetization for different radii of the magnetic disks

Moshchalkov, Victor V.

443

Electric and Magnetic Fields (EMF) RAPID Program Engineering Project 8: FINAL REPORT, Evaluation of Field Reduction Technologies, Volume 1 (Report) and Volume 2 (Appendices)  

SciTech Connect (OSTI)

This draft report consists of two volumes. Volume 1, the main body, contains an introducto~ sectionj an overview of magnetic fields sectio~ and field reduction technology evaluation section. Magnetic field reduction methods are evalpated for transmission lines, distribution Iines,sulxtations, building wiring applkmd machinery, and transportation systems. The evaluation considers effectiveness, co% and other ftiors. Volume 2 contains five appendices, Append~ A presents magnetic field shielding information. Appendices B and C present design assumptions and magnetic field plots for transmission and distribution lines, respectively. Appendices D and E present cost estimate details for transmission and distribution limes, respectively.

Commonwealth Associates, Inc.; IIT Research Institute

1997-08-01T23:59:59.000Z

444

Toroidal vs. poloidal magnetic fields in Sun-like stars: a rotation threshold  

E-Print Network [OSTI]

From a set of stellar spectropolarimetric observations, we report the detection of surface magnetic fields in a sample of four solar-type stars, namely HD 73350, HD 76151, HD 146233 and HD 190771. Assuming that the observed variability of polarimetric signal is controlled by stellar rotation, we establish the rotation periods of our targets, with values ranging from 8.8 d (for HD 190771) to 22.7 d (for HD 146233). Apart from rotation, fundamental parameters of the selected objects are very close to the Sun's, making this sample a practical basis to investigate the specific impact of rotation on magnetic properties of Sun-like stars. We reconstruct the large-scale magnetic geometry of the targets as a low-order (l<10) spherical harmonics expansion of the surface magnetic field. From the set of magnetic maps, we draw two main conclusions. (a) The magnetic energy of the large-scale field increases with rotation rate. The increase of chromospheric emission with the mean magnetic field is flatter than observed ...

Petit, P; Solanki, SK; Donati, J-F; Aurière, M; Lignières, F; Morin, J; Paletou, F; Ramírez, J; Catala, C; Fares, R

2008-01-01T23:59:59.000Z

445

1 Magnetic Fields and Solar This article describesthe relationshipbetweenmagnetic  

E-Print Network [OSTI]

two steps: energy build-up and energy release. The stress and energy are built up by relative motion position minimum energy state. The ex- cess energy is released in the form of kinetic energy magnetic regions of opposite polarities. The line divid- ing two polarities is called the neutral line

446

Magnetic-field-tuned quantum criticality of the heavy-fermion system YbPtBi  

SciTech Connect (OSTI)

In this paper, we present systematic measurements of the temperature and magnetic field dependencies of the thermodynamic and transport properties of the Yb-based heavy fermion YbPtBi for temperatures down to 0.02 K with magnetic fields up to 140 kOe to address the possible existence of a field-tuned quantum critical point. Measurements of magnetic-field- and temperature-dependent resistivity, specific heat, thermal expansion, Hall effect, and thermoelectric power indicate that the AFM order can be suppressed by an applied magnetic field of Hc?4 kOe. In the H-T phase diagram of YbPtBi, three regimes of its low-temperature states emerge: (I) AFM state, characterized by a spin density wave-like feature, which can be suppressed to T=0 by the relatively small magnetic field of Hc?4 kOe; (II) field-induced anomalous state in which the electrical resistivity follows ??(T)?T1.5 between Hc and ?8 kOe; and (III) Fermi liquid (FL) state in which ??(T)?T2 for H?8 kOe. Regions I and II are separated at T=0 by what appears to be a quantum critical point. Whereas region III appears to be a FL associated with the hybridized 4f states of Yb, region II may be a manifestation of a spin liquid state.

Mun, E. D. [Ames Laboratory; Budko, Serguei L. [Ames Laboratory; Martin, Catalin [Ames Laboratory; Kim, Hyong June [Ames Laboratory; Tanatar, Makariy A. [Ames Laboratory; Park, J.-H. [Florida State University; Murphy, T. [Florida State University; Schmiedeshoff, G. M. [Occidental College; Dilley, N. [Quantum Design; Prozorov, Ruslan [Ames Laboratory; Canfield, Paul C. [Ames Laboratory

2013-02-15T23:59:59.000Z

447

Emerging issues in extremely-low-frequency electric and magnetic field health research  

SciTech Connect (OSTI)

Concern has increased over potential consequences of exposure to electric and magnetic fields of extremely low frequency (0-100 Hz), particularly from power transmission and distribution. Also at issue are electrical environments in homes and workplaces. Until recently, research focused on the electric, rather than the magnetic, field; now, both are under extensive investigation. A review of research to date indicates the following: Electric and magnetic fields can produce effects in vitro, with the locus of field interaction believed to be at the cell membrane. Chronic in vivo electric field exposure fails to produce effects except in behavior, neurophysiology, endocrinology, and, possibly, fetal development. The extrapolation of these animal data to humans requires further research. The epidemiological literature has, in some cases, reported an association between increased cancer rates and putative field exposure. Exposure assessments indicate that, in all likelihood, human exposures to 60-Hz electric fields of the magnitudes found under transmission lines are very infrequent; assessments are continuing to characterize exposure to 60-Hz magnetic fields and to measure the field frequency spectra found in residential and workplace settings. The public health issues emerging from this research focus on fetal development and on the initiation or promotion of cancer. It is critical to reduce existing uncertainties in order to enable valid risk assessment.

Kavet, R.I.; Banks, R.S.

1986-04-01T23:59:59.000Z

448

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

SciTech Connect (OSTI)

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

Ludtka, GERALD M.

2005-03-31T23:59:59.000Z

449

Geometrical investigation of the kinetic evolution of the magnetic field in a periodic flux rope  

SciTech Connect (OSTI)

Flux ropes are bundles of magnetic field wrapped around an axis. Many laboratory, space, and astrophysics processes can be represented using this idealized concept. Here, a massively parallel 3D kinetic simulation of a periodic flux rope undergoing the kink instability is studied. The focus is on the topology of the <