An expansion of the field modulus suitable for the description of strong field gradients in axisymmetric magnetic fields: Application to single-sided magnet design, field mapping and STRAFI

Hugon, Cédric; Aubert, G.; Sakellariou, Dimitrios

doi:10.1016/j.jmr.2011.10.015

Cited by 7 publications

(4 citation statements)

References 27 publications

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“…Moving along the axis away from the center of the magnet, one is facing very large gradients in the stray field, which dephases the signal extremely rapidly. While stray-field imaging techniques have used such gradients efficiently 13 , theoretical magnetostatics analysis shows that permanent magnets can be used to shape their profiles and reduce their strength 14 . Here, we used the simplest possible geometry of axially magnetized ring-magnets to show that the stray field gradient could be eliminated in multiple places along the symmetry axis of the superconducting magnet.…”

Section: Theory/methodsmentioning

confidence: 99%

Simple method for the generation of multiple homogeneous field volumes inside the bore of superconducting magnets

Chou

Ferrage

Aubert

et al. 2015

Sci Rep

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Standard Magnetic Resonance magnets produce a single homogeneous field volume, where the analysis is performed. Nonetheless, several modern applications could benefit from the generation of multiple homogeneous field volumes along the axis and inside the bore of the magnet. In this communication, we propose a straightforward method using a combination of ring structures of permanent magnets in order to cancel the gradient of the stray field in a series of distinct volumes. These concepts were demonstrated numerically on an experimentally measured magnetic field profile. We discuss advantages and limitations of our method and present the key steps required for an experimental validation.

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Section: Theory/methodsmentioning

confidence: 99%

Simple method for the generation of multiple homogeneous field volumes inside the bore of superconducting magnets

Chou

Ferrage

Aubert

et al. 2015

Sci Rep

Self Cite

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“…An intricate part of STRAFI experiments is determining the most uniform and strongest gradient region in the stray magnetic field of the superconducting magnet2425. The sweet spot for the STRAFI position was found at 11.2 T with a gradient strength of 72 T/m.…”

Section: Methodsmentioning

confidence: 99%

Non-Destructive Monitoring of Charge-Discharge Cycles on Lithium Ion Batteries using 7Li Stray-Field Imaging

Tang

Dugar

Zhong

et al. 2013

Sci Rep

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Magnetic resonance imaging provides a noninvasive method for in situ monitoring of electrochemical processes involved in charge/discharge cycling of batteries. Determining how the electrochemical processes become irreversible, ultimately resulting in degraded battery performance, will aid in developing new battery materials and designing better batteries. Here we introduce the use of an alternative in situ diagnostic tool to monitor the electrochemical processes. Utilizing a very large field-gradient in the fringe field of a magnet, stray-field-imaging (STRAFI) technique significantly improves the image resolution. These STRAFI images enable the real time monitoring of the electrodes at a micron level. It is demonstrated by two prototype half-cells, graphite∥Li and LiFePO4∥Li, that the high-resolution 7Li STRAFI profiles allow one to visualize in situ Li-ions transfer between the electrodes during charge/discharge cyclings as well as the formation and changes of irreversible microstructures of the Li components, and particularly reveal a non-uniform Li-ion distribution in the graphite.

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“…Many single sided NMR systems have been proposed in the literature [13]. Our approach to magnet design is based on the Spherical Harmonic Decomposition methodology to lead to a 12-fold cylindrically symmetric one-sided constant-gradient magnet without pole pieces [14,15], which has been used already to measure onedimensional proton density profiles as well as relaxations and diffusions [16,17]. Our permanent magnet is a cylinder of 24 cm in diameter, 22 cm in height containing NdFeB magnets and weights ∼ 40 kg.…”

Section: A Home-made Portable Single-sided Nmr Setupmentioning

confidence: 99%

“…Its design consist in a simple dipole pointing along the z direction in the laboratory frame [14,15]. To ease its construction, we assembled and glued all magnet pieces non-magnetized and we magnetized it afterwards in a one-step process using a powerful electromagnet at the LNCMI-CNRS facility [14].…”

Section: A Home-made Portable Single-sided Nmr Setupmentioning

confidence: 99%

Coupling NMR to SANS: Addressing at once structure and dynamics in soft matter

Oliveira‐Silva

Bélime

Cœur

et al. 2020

JNR

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In soft condensed matter, Small Angle Neutron Scattering (SANS) is a central tool to probe structures with characteristic sizes ranging from 1 to 100 nm. However, when used as a standalone technique, the dynamic properties of the sample are not accessible. Nuclear Magnetic Resonance (NMR) is a versatile technique which can easily probe dynamical information. Here, we report on the coupling of a low-field NMR system to a SANS instrument. We show that this original setup makes it possible to obtain structural information and to simultaneously extract in situ on a same sample, long-range translational diffusion coefficient, T 1 and T 2 nuclear spin relaxation times. Such a feature is of major interest when a sample experiences a transient physical state or evolves rapidly. We illustrate the capabilities of alliancing these experimental methods by following the critical temperature-induced phase separation of a concentrated Poly(Methacrylic Acid) solution at its Lower Critical Solution Temperature. The characteristic size related to the domain growth of the polymer-rich phase of the gel is monitored by the evolution of the SANS spectra, while the dynamics of the sol phase (H 2 O and polymer) is simultaneously characterized by NMR by measuring T 1 , T 2 and the diffusion coefficient. Great care has been taken to design a cell able to optimize the thermalization of the sample and in particular its equilibration time. Details are given on the sample cell specifically designed and manufactured for these experiments. The acquisition time needed to reach good signal-to-noise ratios, for both NMR and SANS, match: it is of the order of one hour. Altogether, we show that in situ low-field NMR/SANS coupling the NMR is meaningful and is a promising experimental approach.

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An expansion of the field modulus suitable for the description of strong field gradients in axisymmetric magnetic fields: Application to single-sided magnet design, field mapping and STRAFI

Cited by 7 publications

References 27 publications

Simple method for the generation of multiple homogeneous field volumes inside the bore of superconducting magnets

Simple method for the generation of multiple homogeneous field volumes inside the bore of superconducting magnets

Non-Destructive Monitoring of Charge-Discharge Cycles on Lithium Ion Batteries using 7Li Stray-Field Imaging

Coupling NMR to SANS: Addressing at once structure and dynamics in soft matter

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