scholarly journals Strong Gradients in Weak Magnetic Fields Induce DOLLOP Formation in Tap Water

Water ◽  
2016 ◽  
Vol 8 (3) ◽  
pp. 79 ◽  
Author(s):  
Martina Sammer ◽  
Cees Kamp ◽  
Astrid Paulitsch-Fuchs ◽  
Adam Wexler ◽  
Cees Buisman ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Tap Water ◽  
Weak Field ◽  
Electric Impedance ◽  
Laser Scattering ◽  
Magnetic Inhomogeneities ◽  
Weak Magnetic Fields ◽  
Absolute Strength ◽  
Electric Impedance Spectroscopy ◽  
The Magnetic Field

In 2012 Coey proposed a theory on the mechanism of magnetic water treatment based on the gradient of the applied field rather than its absolute strength. We tested this theory by measuring the effect of very weak field magnets (≤ 10 G) containing strong magnetic inhomogeneities (ΔB = 770 G·m−1 (WCM 62081992) and 740 G·m−1 (WCM 62083545)) on tap water samples by the use of electric impedance spectroscopy (EIS) and laser scattering. Our results show an increased formation of nm-sized prenucleation clusters (dynamically ordered liquid like oxyanion polymers or “DOLLOPs”) due to the exposure to the magnetic field and thus are consistent with Coey’s theory which is therefore also applicable to very weak magnetic fields as long as they contain strong gradients.

scholarly journals Discovery of weak magnetic fields in four DZ white dwarfs in the local 20 pc volume

2019 ◽  
Vol 630 ◽  
pp. A65 ◽  
Author(s):  
S. Bagnulo ◽  
J. D. Landstreet
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
White Dwarfs ◽  
Field Measurements ◽  
Weak Magnetic Fields ◽  
Polluted Atmosphere ◽  
Highly Sensitive ◽  
Cool White Dwarfs ◽  
The Magnetic Field ◽  
Made In

We report the discovery of weak magnetic fields in three white dwarfs within the local 20 pc volume (WD 0816−310, WD 1009−184, and WD 1532+129), and we confirm the magnetic nature of a fourth star (WD 2138−332) in which we had previously detected a field at a 3σ level. The spectra of all these white dwarfs are characterised by the presence of metal lines and lack of H and He lines, that is, they belong to the spectral class DZ. The polarisation signal of the Ca II H+K lines of WD 1009−184 is particularly spectacular, with an amplitude of 20% that is due to the presence of a magnetic field with an average line-of-sight component of 40 kG. We have thus established that at least 40% of the known DZ white dwarfs with an He-rich atmosphere contained in the 20 pc volume have a magnetic field, while further observations are needed to establish whether the remaining DZ white dwarfs in the same volume are magnetic or not. Metal lines in the spectra of DZ white dwarfs are thought to have originated by accretion from rocky debris, and it might be argued that a link exists between metal accretion and higher occurrence of magnetism. However, we are not able to distinguish whether the magnetic field and the presence of a polluted atmosphere have a common origin, or if it is the presence of metal lines that allows us to detect a higher frequency of magnetic fields in cool white dwarfs, which would otherwise have featureless spectra. We argue that the new highly sensitive longitudinal field measurements that we have made in recent years are consistent with the idea that the magnetic field appears more frequently in older than in younger white dwarfs.

scholarly journals Stratification of canopy magnetic fields in a plage region

2020 ◽  
Vol 642 ◽  
pp. A210
Author(s):  
Roberta Morosin ◽  
Jaime de la Cruz Rodríguez ◽  
Gregal J. M. Vissers ◽  
Rahul Yadav
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Strength ◽  
Numerical Models ◽  
Lower Boundary ◽  
Field Approximation ◽  
Weak Field ◽  
Field Vector ◽  
Plage Region ◽  
The Magnetic Field

Context. The role of magnetic fields in the chromospheric heating problem remains greatly unconstrained. Most theoretical predictions from numerical models rely on a magnetic configuration, field strength, and connectivity; the details of which have not been well established with observational studies for many chromospheric scenarios. High-resolution studies of chromospheric magnetic fields in plage are very scarce or non existent in general. Aims. Our aim is to study the stratification of the magnetic field vector in plage regions. Previous studies predict the presence of a magnetic canopy in the chromosphere that has not yet been studied with full-Stokes observations. We use high-spatial resolution full-Stokes observations acquired with the CRisp Imaging Spectro-Polarimeter (CRISP) at the Swedish 1-m Solar Telescope in the Mg I 5173 Å, Na I 5896 Å and Ca II 8542 Å lines. Methods. We have developed a spatially-regularized weak-field approximation (WFA) method, based on the idea of spatial regularization. This method allows for a fast computation of magnetic field maps for an extended field of view. The fidelity of this new technique has been assessed using a snapshot from a realistic 3D magnetohydrodynamics simulation. Results. We have derived the depth-stratification of the line-of-sight component of the magnetic field from the photosphere to the chromosphere in a plage region. The magnetic fields are concentrated in the intergranular lanes in the photosphere and expand horizontally toward the chromosphere, filling all the space and forming a canopy. Our results suggest that the lower boundary of this canopy must be located around 400 − 600 km from the photosphere. The mean canopy total magnetic field strength in the lower chromosphere (z ≈ 760 km) is 658 G. At z = 1160 km, we estimate ⟨B∥⟩ ≈ 417 G. Conclusions. In this study we propose a modification to the WFA that improves its applicability to data with a worse signal-to-noise ratio. We have used this technique to study the magnetic properties of the hot chromospheric canopy that is observed in plage regions. The methods described in this paper provide a quick and reliable way of studying multi layer magnetic field observations without the many difficulties inherent to other inversion methods.

scholarly journals Evolution of quasi-bound states in the circular n–p junction of bilayer graphene under magnetic field

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Haijiao Ji ◽  
Yueting Pan ◽  
Haiwen Liu
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Bound States ◽  
Local Density ◽  
Energy Levels ◽  
Bilayer Graphene ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Weak Magnetic Fields ◽  
The Magnetic Field

Abstract Electron in gapless bilayer graphene can form quasi-bound states when a circular symmetric potential is created in bilayer graphene. These quasi-bound states can be adjusted by tuning the radius and strength of the potential barrier. We investigate the evolution of quasi-bound states spectra in the circular n–p junction of bilayer graphene under the magnetic field numerically. The energy levels of opposite angular momentum split and the splitting increases with the magnetic field. Moreover, weak magnetic fields can slightly shift the energy levels of quasi-bound states. While strong magnetic fields induce additional resonances in the local density states, which originates from Landau levels. We demonstrate that these numerical results are consistent with the semiclassical analysis based on Wentzel–Kramers–Brillouin approximation. Our results can be verified experimentally via scanning tunneling microscopy measurements.

scholarly journals Correction: Sammer, M., et al. Strong Gradients in Weak Magnetic Fields Induce DOLLOP Formation in Tap Water. Water 2016, 8, 79

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1048
Author(s):  
Martina Sammer ◽  
Cees Kamp ◽  
Astrid H. Paulitsch-Fuchs ◽  
Adam D. Wexler ◽  
Cees J. N. Buisman ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Tap Water ◽  
Weak Magnetic Fields

The authors wish to make the following corrections to this paper [1]: In all instances mentioning “2 kG·m−1”, these gradients should be replaced by “770 G·m−1 (WCM 62081992) and 740 G·m−1 (WCM 62083545)”: Abstract, page 1, line 4; Chapter 1 [...]

Analytical Solution of the Perturbed Magnetic Fields of Plates Under Tensile Stress

2008 ◽  
Vol 75 (3) ◽  
Author(s):  
Fei Qin ◽  
Dongmei Yan
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Analytic Solutions ◽  
Round Hole ◽  
Governing Equations ◽  
Displacement Gradient ◽  
Weak Magnetic Fields ◽  
Testing Technology ◽  
Perturbed Magnetic Field ◽  
The Magnetic Field

Development of magnetism based nondestructive testing technology and the Microelectronic mechanical system require accurate computation of perturbed magnetic fields generated by mechanical stress. In this paper, based on the linearized magnetoelastic theory, the governing equations and continuity conditions to determine the perturbed magnetic fields were formulated for the case of weak external magnetic fields such as the earth’s magnetic field. Under those weak magnetic fields, the effect of the magnetic fields on mechanical deformation was neglected. As a result, the interaction between the deformation and the magnetic field was simplified. The effect of deformation on the perturbed magnetic field was taken into account by introducing the displacement gradient into the boundary conditions that the perturbed field should satisfy. As examples, analytic solutions of the perturbed magnetic field of infinite plates with and without a round hole, which are subjected to tensile stresses and weak external magnetic fields, were obtained by the approach presented. The results show that the perturbed magnetic fields induced by stress are three orders less in magnitude of intensity than that of magnetic fields without stress, and some prominent local features such as that has more peaks and decays more rapidly in the radial direction than the case of stress free that are predicted by the solutions.

scholarly journals Magnetic white dwarfs: Observations, theory and future prospects

2016 ◽  
Vol 25 (01) ◽  
pp. 1630005 ◽  
Author(s):  
Enrique García–Berro ◽  
Mukremin Kilic ◽  
Souza Oliveira Kepler
Keyword(s):  
Magnetic Fields ◽  
White Dwarfs ◽  
Current Status ◽  
Future Prospects ◽  
Physical Mechanisms ◽  
Weak Magnetic Fields ◽  
Interesting Class ◽  
The Subject ◽  
Points Of View ◽  
The Magnetic Field

Isolated magnetic white dwarfs have field strengths ranging from [Formula: see text][Formula: see text]G to [Formula: see text][Formula: see text]G, and constitute an interesting class of objects. The origin of the magnetic field is still the subject of a hot debate. Whether these fields are fossil, hence the remnants of original weak magnetic fields amplified during the course of the evolution of the progenitor of white dwarfs, or on the contrary, are the result of binary interactions or, finally, other physical mechanisms that could produce such large magnetic fields during the evolution of the white dwarf itself, remains to be elucidated. In this work, we review the current status and paradigms of magnetic fields in white dwarfs, from both the theoretical and observational points of view.

scholarly journals Ubiquitous hundred-Gauss magnetic fields in solar spicules

2020 ◽  
Vol 642 ◽  
pp. A61
Author(s):  
M. Kriginsky ◽  
R. Oliver ◽  
N. Freij ◽  
D. Kuridze ◽  
A. Asensio Ramos ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Magnetic Fields ◽  
Field Approximation ◽  
Weak Field ◽  
Field Polarity ◽  
Statistical Point ◽  
Quiet Sun ◽  
Solar Spicules ◽  
The Magnetic Field

Aims. We aim to study the magnetic field in solar spicules using high-resolution spectropolarimetric observations in the Ca II 8542 Å line obtained with the Swedish 1-m Solar Telescope. Methods. The equations that result from the application of the weak field approximation (WFA) to the radiative transfer equations were used to infer the line-of-sight (LOS) component of the magnetic field (BLOS). Two restrictive conditions were imposed on the Stokes I and V profiles at each pixel before they could be used in a Bayesian inversion to compute its BLOS. Results. The LOS magnetic field component was inferred in six data sets totalling 448 spectral scans in the Ca II 8542 Å line and containing both active region and quiet Sun areas, with values of hundreds of Gauss being abundantly inferred. There seems to be no difference, from a statistical point of view, between the magnetic field strength of spicules in the quiet Sun or near an active region. On the other hand, the BLOS distributions present smaller values on the disc than off-limb, a fact that can be explained by the effect of superposition on the chromosphere of on-disc structures. We show that on-disc pixels in which the BLOS is determined are possibly associated with spicular structures because these pixels are co-spatial with the magnetic field concentrations at the network boundaries and the sign of their BLOS agrees with that of the underlying photosphere. We find that spicules in the vicinity of a sunspot have a magnetic field polarity (i.e. north or south) equal to that of the sunspot. This paper also contains an analysis of the effect of off-limb overlapping structures on the observed Stokes I and V parameters and the BLOS obtained from the WFA. It is found that this value is equal to or smaller than the largest LOS magnetic field components of the two structures. In addition, using random BLOS, Doppler velocities, and line intensities of these two structures leads in ≃50% of the cases to Stokes I and V parameters that are unsuitable to be used with the WFA. Conclusions. Our results present a scarcity of LOS magnetic field components smaller than some 50 G, which must not be taken as evidence against the existence of these magnetic field strengths in spicules. This fact possibly arises as the consequence of signal superposition and noise in the data. We also suggest that the failure of previous works to infer the strong magnetic fields in spicules detected here is their coarser spatial and/or temporal resolution.

scholarly journals Magnetic fields in astrophysical objects

2008 ◽  
Vol 366 (1884) ◽  
pp. 4453-4464 ◽  
Author(s):  
L.J Silvers
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Accretion Discs ◽  
Weak Magnetic Fields ◽  
Large Scale Magnetic Field ◽  
Astrophysical Objects ◽  
Recent Developments ◽  
The Magnetic Field

Magnetic fields are known to reside in many astrophysical objects and are now believed to be crucially important for the creation of phenomena on a wide variety of scales. However, the role of the magnetic field in the bodies that we observe has not always been clear. In certain situations, the importance of a magnetic field has been overlooked on the grounds that the large-scale magnetic field was believed to be too weak to play an important role in the dynamics. In this article I discuss some of the recent developments concerning magnetic fields in stars, planets and accretion discs. I choose to emphasize some of the situations where it has been suggested that weak magnetic fields may play a more significant role than previously thought. At the end of the article, I list some of the questions to be answered in the future.

Waves in a time-dependent magnetized electron–positron plasma

1999 ◽  
Vol 61 (1) ◽  
pp. 135-150
Author(s):  
E. T. ROWE
Keyword(s):  
Magnetic Fields ◽  
Large Amplitude ◽  
Phase Speed ◽  
Three Solutions ◽  
Amplitude Wave ◽  
Weak Magnetic Fields ◽  
Electron Positron ◽  
The Magnetic Field ◽  
Large Amplitude Wave ◽  
Insight Into

Waves in a magnetized electron–positron plasma, supporting a large-amplitude electric field E0 of superluminal phase speed, are considered. The case of perturbations with the same phase speed as the large-amplitude wave can be treated exactly, and we restrict our attention to this case, obtaining analytical results. The exact analytical results provide insight into the effect of the magnetic field and the large-amplitude wave on the harmonic structure of the perturbations. Three solutions are found for waves polarized perpendicular to E0. Waves are amplitude-modulated for weak magnetic fields (relative to the strength of the large-amplitude wave) and frequency-modulated for strong magnetic fields. This suggests that frequency modulation may be relevant to pulsars.

Application of Magnetovision Scanning System for Detection of Dangerous Objects

2015 ◽  
Vol 220-221 ◽  
pp. 355-360
Author(s):  
Michał Nowicki ◽  
Roman Szewczyk
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Measurement System ◽  
Field Vector ◽  
Magnetic Field Vector ◽  
Scanning System ◽  
Passive Detection ◽  
Weak Magnetic Fields ◽  
The Magnetic Field

This paper presents application of magnetovision scanning system for detection of dangerous objects in weak magnetic fields. Measurement system was developed to study the magnetic field vector distributions. The measurements of the Earth’s field disturbances caused by dangerous ferromagnetic objects were carried out. The ability for passive detection of hidden dangerous objects and determine their location was demonstrated.

Sign in / Sign up

Export Citation Format

Share Document