Simultaneous Magnetic Shielding and Magnetization Loss Measurements of YBCO Cylinders at Variable Temperatures Under Cryogenic Helium Gas Circulation

Kvitkovič, J.; Hatwar, Rajeev; Pamidi, Sastry

doi:10.1109/tasc.2016.2525932

Cited by 5 publications

(1 citation statement)

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“…Hollow superconducting materials used as magnetic shields have been studied mainly under a homogeneous applied magnetic field or in situations where the shielding current path is a priori known. The various shapes investigated include tubes [8,[11][12][13][14], plates [15], tapes [16][17][18], cups [19,20], as well as structures made of different elements. In a homogeneous magnetic field the cause of the physical phenomenon, i.e.…”

Section: Introductionmentioning

confidence: 99%

Bulk superconducting tube subjected to the stray magnetic field of a solenoid

Hogan

Fagnard

Wera

et al. 2017

Supercond. Sci. Technol.

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Hard type-II hollow superconductors are well suited for low frequency magnetic shielding. The properties and performances of superconducting magnetic shields subjected to homogeneous magnetic fields have been extensively discussed in the literature. In the present work, we investigate the magnetic shielding and the penetration of magnetic flux in a bulk high temperature superconducting tube subjected to the inhomogeneous fringe field of a solenoidal coil. Thanks to a bespoke microdisplacement measurement system, we measure the magnetic field distribution around the tube. We develop a full 3D finite element model based on an H formulation to understand the flux penetration mechanisms and predict the shape of the current loops. Using constitutive law parameters obtained from previous independent experiments, our model is found to be in excellent agreement with the measurements. We discuss how to assess the degree of inhomogeneity of the magnetic field and show that, in our case study, the field can be treated as the magnetic field of an equivalent magnetic dipole. We also show that some features of the flux penetration in inhomogeneous field can be also observed when the tube is subjected to an oblique homogeneous magnetic field, which offers a better understanding of the shielding current density distribution inside the shield. Finally, we discuss the magnetic field concentration occurring around the shield for different magnetic field configurations. In particular, we show that the extremities of the tube on the side not facing the magnetic field source experience the highest flux concentration.

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Section: Introductionmentioning

confidence: 99%

Bulk superconducting tube subjected to the stray magnetic field of a solenoid

Hogan

Fagnard

Wera

et al. 2017

Supercond. Sci. Technol.

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Magnetic shielding of long paraboloid structures in the inhomogeneous magnetic field

Kvitkovič¹,

Burnside

Zhang³

et al. 2020

J. Phys.: Conf. Ser.

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Shielding efficacy of the high-temperature superconducting (HTS) magnetic shields depends on the superconductor properties and on the orientation of the external magnetic field. For precise magnetic field measurements in areas with changing direction of magnetic noise it is important to reduce both the parallel and perpendicular components of the magnetic field. We have designed and fabricated magnetic shields of 25 cm long paraboloid shape with closed sides from second-generation HTS tapes. We have characterized HTS shields in DC and variable frequency AC magnetic fields at 77 K above a copper electromagnet acting as the source of inhomogeneous magnetic noise. The HTS magnetic shields reduce the magnetic field noise penetration and enhance the sensitivity of magnetic field sensors. The measurements were performed with the magnetic shield placed between the noise source and the sensor. 2D finite element analysis using Comsol model was generated and the results were compared with the experimental data of magnetic field dependences of the shielding factor (SF).

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