Design criteria for active shielding of inhomogeneous magnetic fields for biomagnetic applications

Urankar, L.; Oppelt, Ralph

doi:10.1109/10.503177

Cited by 13 publications

(18 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This extends the work of Ref. 23 from spherical to cylindrical geometries; for the spherical case, we demonstrate agreement with Ref. 23 .…”

Section: Introductionsupporting

confidence: 91%

“…However, as mentioned above, these authors considered only uniform applied fields. Urankar and Oppelt 23 analyzed the general multipole field (both as an external and internal source) for single spherical shields, and provided general shielding and reaction factors. They employed their the results to analyze active magnetic compensation used in conjunction with magnetically shielded rooms.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Passive magnetic shielding in static gradient fields

Bidinosti

Martin

2014

AIP Advances

View full text Add to dashboard Cite

The effect of passive magnetic shielding on dc magnetic field gradients imposed by both external and internal sources is studied. It is found that for concentric cylindrical or spherical shells of high permeability material, higher order multipoles in the magnetic field are shielded progressively better, by a factor related to the order of the multipole. In regard to the design of internal coil systems for the generation of uniform internal fields, we show how one can take advantage of the coupling of the coils to the innermost magnetic shield to further optimize the uniformity of the field. These results demonstrate quantitatively a phenomenon that was previously well-known qualitatively: that the resultant magnetic field within a passively magnetically shielded region can be much more uniform than the applied magnetic field itself. Furthermore we provide formulae relevant to active magnetic compensation systems which attempt to stabilize the interior fields by sensing and cancelling the exterior fields close to the outermost magnetic shielding layer. Overall this work provides a comprehensive framework needed to analyze and optimize dc magnetic shields, serving as a theoretical and conceptual design guide as well as a starting point and benchmark for finite-element analysis.

show abstract

“…This extends the work of Ref. 23 from spherical to cylindrical geometries; for the spherical case, we demonstrate agreement with Ref. 23 .…”

Section: Introductionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Passive magnetic shielding in static gradient fields

Bidinosti

Martin

2014

AIP Advances

View full text Add to dashboard Cite

show abstract

“…where P n (u) is the Legendre function of degree n and the term in square braces, known as the reaction factor [8,10], quantifies the extent to which the n-th term in the field expansion is augmented by the presence of the shield. An important consequence of the reaction factor, discussed further below, is that the homogeneity of the field of a spherical coil may either improve or degrade inside a shield depending on the ratio a/b [8].…”

Section: The Spherical Coil Inside a Spherical Shieldmentioning

confidence: 99%

Analytic models of magnetically enclosed spherical and solenoidal coils

Liu

Andalib

Ostapchuk

et al. 2020

Nuclear Instruments and Methods in Physics Research Section A:

View full text Add to dashboard Cite

We provide analytic solutions of the net magnetic field generated by spherical and solenoidal coils enclosed in highly-permeable, coaxial magnetic shields.We consider both spherical and cylindrical shields in the case of the spherical coil and only cylindrical shields for the solenoidal coil. Comparisons of field homogeneity are made and we find that the solenoidal coil produces the more homogeneous field for a given number of windings. The models are useful as theoretical and conceptual guides for coil design, as well as for benchmarking finite-element analysis. We also demonstrate how the models can be generalized to explore field inhomogeneities related to winding misplacement.

show abstract

“…For closed objects, such as spherical shells [26,27], the shielding factor approaches infinity as µ → ∞, and | µ The simulations differed slightly in their results, dependent on whether OPERA or FEMM was used, and whether the solenoidal coil or loop coil were used. Based on the simulations, the result is | µ Bs dBs dµ | = 0.42 − 0.50 for the solenoidal coil, with the lower value being given by FEMM and the upper value being given by a 3D OPERA simulation, for identical geometries.…”

Section: Geometry Correction and Determination Of µ(T )mentioning

confidence: 99%

Sensitivity of fields generated within magnetically shielded volumes to changes in magnetic permeability

Andalib

Martin

Bidinosti

et al. 2017

Nuclear Instruments and Methods in Physics Research Section A:

View full text Add to dashboard Cite

Future experiments seeking to measure the neutron electric dipole moment (nEDM) require stable and homogeneous magnetic fields. Normally these experiments use a coil internal to a passively magnetically shielded volume to generate the magnetic field. The stability of the magnetic field generated by the coil within the magnetically shielded volume may be influenced by a number of factors. The factor studied here is the dependence of the internally generated field on the magnetic permeability µ of the shield material. We provide measurements of the temperature-dependence of the permeability of the material used in a set of prototype magnetic shields, using experimental parameters nearer to those of nEDM experiments than previously reported in the literature. Our measurements imply a range of 1 µ dµ dT from 0-2.7%/K. Assuming typical nEDM experiment coil and shield parameters gives µ B0 dB0 dµ = 0.01, resulting in a temperature dependence of the magnetic field in a typical nEDM experiment of dB0 dT = 0 − 270 pT/K for B 0 = 1 µT. The results are useful for estimating the necessary level of temperature control in nEDM experiments.

show abstract

Design criteria for active shielding of inhomogeneous magnetic fields for biomagnetic applications

Cited by 13 publications

References 7 publications

Passive magnetic shielding in static gradient fields

Passive magnetic shielding in static gradient fields

Analytic models of magnetically enclosed spherical and solenoidal coils

Sensitivity of fields generated within magnetically shielded volumes to changes in magnetic permeability

Contact Info

Product

Resources

About