Eddy current losses in finite length conducting cylinders

Fawzi, T.; Ali, K. F.; Burke, P.

doi:10.1109/tmag.1983.1062759

Cited by 17 publications

(10 citation statements)

References 6 publications

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“…The nonlinearity is rather severe near the fully extended rod position. This results supports earlier research that recommended the use of aluminum rather than copper in eddy current sensor applications [26]. Steel appears to be a good core material, as shown by the impedance data in Fig.…”

Section: Other Rod Materialssupporting

confidence: 90%

A displacement sensor for nonmetallic hydraulic cylinders

2003

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A sensor was developed to provide signals proportional to the position of the rod in a hydraulic cylinder. The sensor has a coil winding in the shell of the cylinder. The sensor operates by sensing the change in the coil impedance as the rod moves in the cylinder. This paper describes the construction of the cylinder and the sensor, and the performance evaluation of the sensor. Several different materials were placed in the rod and tested. For the cylinder tested, an aluminum core provided the highest precision, about 0.38 . The full-scale output was 19.90 over a stroke length of 193 mm. The linearity was about 1.64% of full-scale. Shielding from electromagnetic interference can improve the precision dramatically. A ferrite-cored rod assembly yielded a much greater full-scale output, 1300 , but exhibited significant hysteresis.

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Section: Other Rod Materialssupporting

confidence: 90%

A displacement sensor for nonmetallic hydraulic cylinders

2003

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“…The 4.2 K electrical conductivity of this copper is σ cu ∼ 5.25 × 10 9 (Ωm) −1 . By applying a boundary elements numerical method [13] it can be estimated that the power dissipated by eddy current losses should reduce the quality factor to ∼ 10 4 when the copper cylinder is fully inserted into the superconducting coil. A motion feedthrough allows to move the cylinder from the inside of the superconducting support of the capacitors (where it is shielded from the coil field and does not add dissipation) into the middle of the coil.…”

Section: A Model For the Resonator Current Noisementioning

confidence: 99%

Thermal noise in a high Q cryogenic resonator

Bonaldi

Falferi

Cerdonio

et al. 1999

Review of Scientific Instruments

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In order to evaluate the feasibility of a mixed mechanical and electrical multimode matching network for a resonant gravitational wave detector, current noise measurements were performed on a high quality factor LC resonator, based on a superconducting coil, by using a dc SQUID weakly coupled to the coil. We present a method to identify different noise sources in the system by their dependence on the temperature or on the resonator quality factor. Measurements performed at quality factors up to 10 6 in the temperature range 1.2-4.2 K, show that the total measured noise is only contributed by the resonator thermal noise.

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“…Areas such as electrodynamics, acoustics, continuum mechanics, dynamics of structures, and others can all benefit from adding another powerful mathematical tool which can be used to help solve problems which exhibit circular cylindrical symmetry. There is no theoretical reason prohibiting the a p plication of the Q-function t o electrodynamic problems such as electromagnetic radiation problems given in Overfelt (1996) and Werner (2000), eddy current formulations given in Hagel, Gong, and Unbehauen (1992), and Fawzi, Ali, and Burke (1983), and Dodd and Deeds (1968). Also, one could employ Q-functions for time varying electric and magnetic field formulations given by Lahart (2004) and Avilia (2003), etc.…”

Section: Ir -mentioning

confidence: 99%

A General Method for Calculating the External Magnetic Field from a Cylindrical Magnetic Source using Toroidal Functions

Selvaggi¹,

Salon²,

Chari³

2006

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An alternative method is developed t o compute the magnetic field from a circular cylindrical magnetic source. Specifically, a Fourier series expansion whose coefficients are toroidal functions is introduced which yields an alternative to the more familiar spherical harmonic solution or the Elliptic integral solution.This alternate formulation coupled with a method called charge simulation allows one to compute the external magnetic field from an arbitrary magnetic source in terms of a toroidal expansion. This expansion is valid on any finite hypothetical external observation cylinder. In other words, the magnetic scalar potential or the magnetic field intensity is computed on a exterior cylinder which encloses the magnetic source. This method can be used to accurately compute the far field where a finite element formulation is known t o be inaccurate.

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Eddy current losses in finite length conducting cylinders

Cited by 17 publications

References 6 publications

A displacement sensor for nonmetallic hydraulic cylinders

A displacement sensor for nonmetallic hydraulic cylinders

Thermal noise in a high Q cryogenic resonator

A General Method for Calculating the External Magnetic Field from a Cylindrical Magnetic Source using Toroidal Functions

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