A Systematic Approach to the Design, Fabrication and Testing of Permanent Magnets Applied to Single-Sided NMR

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

doi:10.1063/1.3562244

Cited by 8 publications

(9 citation statements)

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“…This section focuses on results published earlier in [9,17] and presented here for convenience. We consider here a situation where the distribution of field sources (currents, poles) is axially symmetric.…”

Section: She-based Framework For Axially-symmetric Strong 1d Gradientsmentioning

confidence: 99%

“…15. Because of their portability, permanent magnets are often chosen to realize single-sided systems [7,9,[19][20][21]. However, no real systematic approach has been proposed until now to design such magnet systems.…”

Section: Single-sided Magnet Design and Shimmingmentioning

confidence: 99%

“…This is one of the goals of stray-field imaging (STRAFI), where the sample is placed in the stray-field of a powerful NMR magnet so that field gradients of the order of 10-100 T m À1 can be obtained [5]. Intense gradients can also be obtained with single-sided permanent magnets [6][7][8][9]. In such cases, the SHE approximation cannot be used anymore: the field modulus variations are not dominated by only one Cartesian component but involve all of them.…”

Section: Introductionmentioning

confidence: 99%

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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

Hugon¹,

Aubert²,

Sakellariou³

2012

Journal of Magnetic Resonance

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Mapping (or plotting) the magnetic field has a critical importance for the achievement of the homogeneous magnetic field necessary to standard MR experiments. A powerful tool for this purpose is the Spherical Harmonic Expansion (SHE), which provides a simple way to describe the spatial variations of a field in free space. Well-controlled non-zero spatial variations of the field are critical to MRI. The resolution of the image is directly related to the strength of the gradient used to encode space. As a result, it is desirable to have strong variations of the field. In that case, the SHE cannot be used as is, because the field modulus variations are affected by the variations of all components of the field. In this paper, we propose a method based on the SHE to characterize such variations, theoretically and experimentally, in the limit of an axisymmetric magnetic field. Practical applications of this method are proposed through the examples of single-sided magnet design and characterization, along with Stray-Field Imaging (STRAFI).

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Section: She-based Framework For Axially-symmetric Strong 1d Gradientsmentioning

confidence: 99%

Section: Single-sided Magnet Design and Shimmingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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

Hugon¹,

Aubert²,

Sakellariou³

2012

Journal of Magnetic Resonance

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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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