Effects of Low Magnetic Fields on Gold-YBCO Contacts

1989 ◽  
Vol 169 ◽  
Author(s):  
Yonhua Tzeng ◽  
Mitchell A. Belser
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
Electrical Properties ◽  
Magnetic Fields ◽  
Contact Resistance ◽  
High Magnetic Field ◽  
High Current ◽  
Long Time ◽  
Low Magnetic Field ◽  
The Magnetic Field

AbstractThe effects of low magnetic field (0–40 Gauss) on electrical properties of gold-YBCO contacts are investigated. The contact resistance increases significantly with applied magnetic fields. For high magnetic field or when high current is flowing through the contact, the contact resistance decays after removing the magnetic field to a finite value greater than that is measured before the contact is exposed to the magnetic field and stays there for long time as long as the sample is kept below the superconductivity critical temperature.

Structural and magnetic properties of high magnetic-field-assisted hydrothermal synthesized Bi6Fe2Ti3O18 particles

2019 ◽  
Vol 34 (03) ◽  
pp. 2050043
Author(s):  
Shengman Liu
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Magnetic Fields ◽  
Hydrothermal Method ◽  
High Magnetic Field ◽  
Growth Behavior ◽  
High Magnetic Fields ◽  
Structural And Magnetic Properties ◽  
Ferromagnetic Ordering ◽  
The Magnetic Field

[Formula: see text] (BFTO) nanoparticles were successfully synthesized by hydrothermal method in high magnetic fields of 0T, 2T, 4T, and 8T. High magnetic field can greatly affect the growth behavior of BFTO particles. The magnetic fields promote the BFTO nanoplates to grow along (001) direction and form a high-index {115} facet. The BFTO samples prepared in different magnetic fields are paramagnetic with the presence of an antiferromagnetic (AFM) and ferromagnetic ordering, and the AFM interaction weakens when the magnetic field is increased. In particular, the magnetization of the as-prepared BFTO particles is slightly enhanced with the increase in magnetic fields arising from the increased amount of bipyramid particles in favor of [Formula: see text]–[Formula: see text] plane alignment parallel to the magnetic field.

Preparation and Electrical Properties of Aligned Carbon Nanotubes/Epoxy Resin Composites Induced by a Low Magnetic Field

2011 ◽  
Vol 189-193 ◽  
pp. 1340-1343 ◽  
Author(s):  
Yu Zhang ◽  
Chuan Guo Ma
Keyword(s):  
Magnetic Field ◽  
Carbon Nanotubes ◽  
Electrical Properties ◽  
Epoxy Resin ◽  
Field Direction ◽  
Magnetic Field Direction ◽  
Aligned Carbon Nanotubes ◽  
Low Magnetic Field ◽  
The Magnetic Field ◽  
Properties Of Composites

Aligned carbon nanotubes(CNTs)/epoxy resin(EP) composites were prepared under a low magnetic field (B<500mT) induction. The effect of different magnetic fields on the electrical and dielectrical properties of composites was investigated. The results show that the CNTs are aligned with rod-like aggregations instead of single CNTs when the magnetic field direction is vertical to the casting direction of samples, then electric conductivity, permittivity, dielectric loss of the composite are improved. And a larger magnetic field intensity and a bigger mould capacity can help the effect of magnetic field induction. However the CNTs are seriously aggregated and the electrical properties of composites change worse when the magnetic field direction is parallel to the casting direction of samples.

scholarly journals High magnetic field pulsars with magnetar-like activity

2012 ◽  
Vol 8 (S291) ◽  
pp. 351-351
Author(s):  
Yuta Aoki
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Thermal Radiation ◽  
High Magnetic Field ◽  
Observational Result ◽  
Radio Pulsars ◽  
X Ray ◽  
S Period ◽  
The Magnetic Field

AbstractTo study the origin of magnetars, a unique opportunity is provided by detecting an excess of X-ray thermal radiation of the radio pulsars (rotation powered pulsars) with dipolar magnetic fields as high as magnetars. The excess is probably caused by decay of the magnetic field as seen in magnetars. In order to investigate whether the rotation powered pulsars have the excess flux and the hard-tail component similar to magnetars, we observed PSR J0726-2612 which has a 3.44 s period and a 3 × 1013 G inferred dipolar magnetic field, with Suzaku for 44 ks on 2011 November 16-17. We report this observational result. We also compare with other observations and discuss a decaying of the magnetic field for normal radio pulsars.

Variation of Surface Tension of Water in High Magnetic Field

2013 ◽  
Vol 750-752 ◽  
pp. 2279-2282 ◽  
Author(s):  
Long Chen ◽  
Chuan Jun Li ◽  
Zhong Ming Ren
Keyword(s):  
Magnetic Field ◽  
Surface Tension ◽  
Magnetic Fields ◽  
Hydrogen Bonds ◽  
High Magnetic Field ◽  
Field Intensity ◽  
Magnetic Field Intensity ◽  
High Magnetic Fields ◽  
The Magnetic Field

The surface tension of water in high magnetic fields up to 10T was investigated with aid of the high-magnetic-field tensiometer (HMFT). It was found that the surface tension of water linearly varied with the magnetic field intensity and increased by 0.48mN/m or 0.65% in 10T. The increase of the surface tension of water could be attributed to the increase in the number and stabilization of the hydrogen bonds in the magnetic field.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust &amp; Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust &amp; Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

scholarly journals An 84-μG Magnetic Field in a Galaxy at Z=0.692?

2008 ◽  
Vol 4 (S254) ◽  
pp. 95-96
Author(s):  
Arthur M. Wolfe ◽  
Regina A. Jorgenson ◽  
Timothy Robishaw ◽  
Carl Heiles ◽  
Jason X. Prochaska
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Faraday Rotation ◽  
Large Scale ◽  
Dynamo Model ◽  
Magnetic Field Generation ◽  
Interstellar Gas ◽  
Splitting Technique ◽  
Average Value ◽  
The Magnetic Field

AbstractThe magnetic field pervading our Galaxy is a crucial constituent of the interstellar medium: it mediates the dynamics of interstellar clouds, the energy density of cosmic rays, and the formation of stars (Beck 2005). The field associated with ionized interstellar gas has been determined through observations of pulsars in our Galaxy. Radio-frequency measurements of pulse dispersion and the rotation of the plane of linear polarization, i.e., Faraday rotation, yield an average value B ≈ 3 μG (Han et al. 2006). The possible detection of Faraday rotation of linearly polarized photons emitted by high-redshift quasars (Kronberg et al. 2008) suggests similar magnetic fields are present in foreground galaxies with redshifts z > 1. As Faraday rotation alone, however, determines neither the magnitude nor the redshift of the magnetic field, the strength of galactic magnetic fields at redshifts z > 0 remains uncertain.Here we report a measurement of a magnetic field of B ≈ 84 μG in a galaxy at z =0.692, using the same Zeeman-splitting technique that revealed an average value of B = 6 μG in the neutral interstellar gas of our Galaxy (Heiles et al. 2004). This is unexpected, as the leading theory of magnetic field generation, the mean-field dynamo model, predicts large-scale magnetic fields to be weaker in the past, rather than stronger (Parker 1970).The full text of this paper was published in Nature (Wolfe et al. 2008).

Magnetic Field Spectroheliograms from the San Fernando Observatory

1971 ◽  
Vol 43 ◽  
pp. 329-339 ◽  
Author(s):  
Dale Vrabec
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Spiral Structure ◽  
Longitudinal Component ◽  
Solar Telescope ◽  
Solar Magnetic Fields ◽  
San Fernando ◽  
Field Lines ◽  
The Magnetic Field ◽  
Field Network

Zeeman spectroheliograms of photospheric magnetic fields (longitudinal component) in the CaI 6102.7 Å line are being obtained with the new 61-cm vacuum solar telescope and spectroheliograph, using the Leighton technique. The structure of the magnetic field network appears identical to the bright photospheric network visible in the cores of many Fraunhofer lines and in CN spectroheliograms, with the exception that polarities are distinguished. This supports the evolving concept that solar magnetic fields outside of sunspots exist in small concentrations of essentially vertically oriented field, roughly clumped to form a network imbedded in the otherwise field-free photosphere. A timelapse spectroheliogram movie sequence spanning 6 hr revealed changes in the magnetic fields, including a systematic outward streaming of small magnetic knots of both polarities within annular areas surrounding several sunspots. The photospheric magnetic fields and a series of filtergrams taken at various wavelengths in the Hα profile starting in the far wing are intercompared in an effort to demonstrate that the dark strands of arch filament systems (AFS) and fibrils map magnetic field lines in the chromosphere. An example of an active region in which the magnetic fields assume a distinct spiral structure is presented.

scholarly journals No-z Model for Magnetic Fields of Different Astrophysical Objects and Stability of the Solutions

Data ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 4
Author(s):  
Evgeny Mikhailov ◽  
Daniela Boneva ◽  
Maria Pashentseva
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Point Of View ◽  
Accretion Discs ◽  
Wide Range ◽  
Astrophysical Objects ◽  
Alpha Effect ◽  
The Stability ◽  
The Magnetic Field

A wide range of astrophysical objects, such as the Sun, galaxies, stars, planets, accretion discs etc., have large-scale magnetic fields. Their generation is often based on the dynamo mechanism, which is connected with joint action of the alpha-effect and differential rotation. They compete with the turbulent diffusion. If the dynamo is intensive enough, the magnetic field grows, else it decays. The magnetic field evolution is described by Steenbeck—Krause—Raedler equations, which are quite difficult to be solved. So, for different objects, specific two-dimensional models are used. As for thin discs (this shape corresponds to galaxies and accretion discs), usually, no-z approximation is used. Some of the partial derivatives are changed by the algebraic expressions, and the solenoidality condition is taken into account as well. The field generation is restricted by the equipartition value and saturates if the field becomes comparable with it. From the point of view of mathematical physics, they can be characterized as stable points of the equations. The field can come to these values monotonously or have oscillations. It depends on the type of the stability of these points, whether it is a node or focus. Here, we study the stability of such points and give examples for astrophysical applications.

scholarly journals The Origin and Dynamical Effects of the Magnetic Fields and Cosmic Rays in the Disk of the Galaxy

1970 ◽  
Vol 39 ◽  
pp. 168-183
Author(s):  
E. N. Parker
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Magnetic Fields ◽  
Dynamical Behavior ◽  
Cosmic Ray ◽  
Interested Reader ◽  
Written Text ◽  
The Galaxy ◽  
Basic Ideas ◽  
The Magnetic Field

The topic of this presentation is the origin and dynamical behavior of the magnetic field and cosmic-ray gas in the disk of the Galaxy. In the space available I can do no more than mention the ideas that have been developed, with but little explanation and discussion. To make up for this inadequacy I have tried to give a complete list of references in the written text, so that the interested reader can pursue the points in depth (in particular see the review articles Parker, 1968a, 1969a, 1970). My purpose here is twofold, to outline for you the calculations and ideas that have developed thus far, and to indicate the uncertainties that remain. The basic ideas are sound, I think, but, when we come to the details, there are so many theoretical alternatives that need yet to be explored and so much that is not yet made clear by observations.

scholarly journals Broadband Linear Polarization in Ap Stars

1993 ◽  
Vol 138 ◽  
pp. 305-309
Author(s):  
Marco Landolfi ◽  
Egidio Landi Degl’Innocenti ◽  
Maurizio Landi Degl’Innocenti ◽  
Jean-Louis Leroy ◽  
Stefano Bagnulo
Keyword(s):  
Magnetic Field ◽  
Circular Polarization ◽  
Linear Polarization ◽  
Rotation Axis ◽  
Spectral Lines ◽  
Line Of Sight ◽  
Long Time ◽  
Rotating Star ◽  
Ap Stars ◽  
The Magnetic Field

AbstractBroadband linear polarization in the spectra of Ap stars is believed to be due to differential saturation between σ and π Zeeman components in spectral lines. This mechanism has been known for a long time to be the main agent of a similar phenomenon observed in sunspots. Since this phenomenon has been carefully calibrated in the solar case, it can be confidently used to deduce the magnetic field of Ap stars.Given the magnetic configuration of a rotating star, it is possible to deduce the broadband polarization at any phase. Calculations performed for the oblique dipole model show that the resulting polarization diagrams are very sensitive to the values of i (the angle between the rotation axis and the line of sight) and β (the angle between the rotation and magnetic axes). The dependence on i and β is such that the four-fold ambiguity typical of the circular polarization observations ((i,β), (β,i), (π-i,π-β), (π-β,π-i)) can be removed.

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