Calculation of magnetic field noise from high-permeability magnetic shields and conducting objects with simple geometry

Journal of Applied Physics

Volumn 103, Issue 8, 2008, Pages

  Lee, S K ^a   Romalis, M V ^a  

^a PRINCETON UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

FINITE ELEMENT METHOD; MAGNETIC FIELD EFFECTS; MAGNETIC PERMEABILITY; PRECISION ENGINEERING;

AXIALLY SYMMETRIC GEOMETRIES; MAGNETIC FIELD NOISE; PRECISION MEASUREMENTS;

MAGNETIC SHIELDING;

EID: 43049090882     PISSN: 00218979     EISSN: None     Source Type: Journal    
DOI: 10.1063/1.2885711     Document Type: Article

References (24)

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17. This comes from the fact that for a given shield size and shape, the reluctance of the portion of the magnetic circuit that goes through the shield scales with the thickness and the permeability as Rmagn 1/ (μr t). Therefore qualitative distribution of field lines around the shield should not change as μr and t vary while keeping their product constant. The other length scale relevant to the problem is a, which leads to the dimensionless parameter specified.
18. Obviously this does not hold at the corners of a closed cylindrical shield. However, numerical finite-element calculations in Appendix indicate that errors in noise due to these localized points are at most on the order of 1%.
19. W. R. Smythe, Static and Dynamic Electricity (McGraw-Hill, New York, 1968), pp. 188-190.
20. The integrand diverges at x′ =1/2, but the integral converges when the upper limit of integral approaches 1/2 from below.
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22. See their Eq. (45) and an expression in the following paragraph.
23. See their Eq. (5) in the case dt.
24. This is the case after correcting the definition of 2 by multiplying it with z2 in order to render it dimensionless as claimed.