Multipole Analysis of Circular Cylindircal Magnetic Systems

Selvaggi, Jerry P.

doi:10.2172/875456

Cited by 10 publications

(13 citation statements)

References 81 publications

(102 reference statements)

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“…Notice that for increasing magnetic moment the ratio T c (µ)/T c becomes lower than one, indicating that the height of the cylinder matters in this case, and our theoretical considerations developed in the ring limit applies to this situation and is determined by Eq. (20) and not by Eq. (34).…”

Section: Numerical Analysismentioning

confidence: 93%

“…, and, (24) (1), (6), (7) and (11), respectively, are depicted as red dashed vertical lines and are selected for further analysis in Fig.(12). (20) (1)…”

Section: The Ring Limitmentioning

confidence: 99%

“…According to Eq. (20) this occurs when the LP temperature becomes the critical one. However the condition T c(µ)/T c = 1 is the same as g(µ) = 0.…”

Section: The Ring Limitmentioning

confidence: 99%

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Little-Parks oscillations near a persistent current loop

2012

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We investigate the Little-Parks oscillations caused by a persistent current loop set on the top edge of a mesoscopic superconducting thin-walled cylinder with a finite height. For a short cylinder the Little-Parks oscillations are approximately the same ones of the standard effect, as there is only one magnetic flux piercing the cylinder. For a tall cylinder the inhomogeneity of the magnetic field makes different magnetic fluxes pierce the cylinder at distinct heights and we show here that this produces two distinct Little-Parks oscillatory regimes according to the persistent current loop. We show that these two regimes, and also the transition between them, are observable in current measurements done in the superconducting cylinder. The two regimes stem from different behavior along the height, as seen in the order parameter, numerically obtained from the Ginzburg-Landau theory through the finite element method.

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Section: Numerical Analysismentioning

confidence: 93%

“…, and, (24) (1), (6), (7) and (11), respectively, are depicted as red dashed vertical lines and are selected for further analysis in Fig.(12). (20) (1)…”

Section: The Ring Limitmentioning

confidence: 99%

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Little-Parks oscillations near a persistent current loop

2012

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“…The first type of charge simulation, used in this paper, is that derived from a known magnetic scalar potential function. The second type of charge simulation, illustrated in Selvaggi (2005), is that derived from experimental data such as the normal component of the magnetic flux density measured on a closed hypothetical cylinder surrounding a real magnetic source.…”

Section: Formulationmentioning

confidence: 99%

Computing the External Magnetic Scalar Potential due to an Unbalanced Six-Pole Permanent Magnet Motor

Selvaggi¹,

Salon²,

Kwon³

et al. 2007

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The accurate computation of the external magnetic field from a permanent magnet motor is accomplished by first computing its magnetic scalar potential. In order to find a solution which is valid for any arbitrary point external to the motor, a number of proven methods have been employed. Firstly, A finite element model is developed which helps generate magnetic scalar potential values valid for points close to and outside the motor. Secondly, charge simulation is employed which generates an equivalent magnetic charge matrix. Finally, an equivalent multipole expansion is developed through the application of a toroidal harmonic expansion. This expansion yields the harmonic components of the external magnetic scalar potential which can be used to compute the magnetic field at any point outside the motor.

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“…The advance involves solving Poisson's equation with the particular inhomogeneous Dirichlet-type boundary conditions, dictated by the induced surface magnetic charges. A most straightforward way for applying the general integral form of solution turns out to be the use of the required Green's function in terms of toroidal functions (Cohl et al 2000); recently, Selvaggi (2005Selvaggi ( , 2008 has revived the interest in these functions by their successful and systematic implementation to the solution of magnetic, electrostatic and gravitational problems of potential theory. The stray magnetic field then follows in §2c through, essentially, straightforward differentiation in toroidal coordinates.…”

Section: Introductionmentioning

confidence: 99%

Magnetostatics of the uniformly polarized torus

2009

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We provide an exhaustive description of the magnetostatics of the uniformly polarized torus and its derivative self-intersecting (spindle) shapes. In the process, two complementary approaches have been implemented, position-space analysis of the Laplace equation with inhomogeneous boundary conditions and a Fourier-space analysis, starting from the determination of the shape amplitude of this topologically non-trivial body. The stray field and the demagnetization tensor have been determined as rapidly converging series of toroidal functions. The single independent demagnetization-tensor eigenvalue has been determined as a function of the unique aspect ratio α of the torus. Throughout the range of values of the ratio, corresponding to a multiply connected torus proper, the axial demagnetization factor N z remains close to one half. There is no breach of smoothness of N z (α) at the topological crossover to a simply connected tight torus (α = 1). However, N z is a non-monotonic function of the aspect ratio, such that substantially different pairs of corresponding tori would still have the same demagnetization factor. This property does not occur in a simply connected body of the same continuous axial symmetry. Several self-suggesting practical applications are outlined, deriving from the acquired quantitative insight.

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Multipole Analysis of Circular Cylindircal Magnetic Systems

Abstract: An Abstract of a Thesis Submitted to the Graduate

Cited by 10 publications

References 81 publications

Little-Parks oscillations near a persistent current loop

Little-Parks oscillations near a persistent current loop

Computing the External Magnetic Scalar Potential due to an Unbalanced Six-Pole Permanent Magnet Motor

Magnetostatics of the uniformly polarized torus

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