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Novel Superconducting Shield

IP.com Disclosure Number: IPCOM000042203D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bermon, S: AUTHOR [+6]

Abstract

This article relates generally to magnetic shields and more particularly to a superconducting shield having a composition gradient which is capable of providing a low magnetic field environment. The figure shows a cross-sectional view of a cryostat 1 immersed in a container (not shown) of liquid helium. The cryostat holds an exchange gas which is utilized to cool a superconducting shield 2. Shield 2 is comprised of a superconducting material which has a composition gradient which varies from the bottom of shield 2 to its top. As a result of the composition gradient, the Tc for the normal-superconducting transition of the material also varies along shield 2. The composition gradient insures that a shield, which is cooled uniformly, passes into the superconducting state in a smooth fashion following the material gradient.

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Novel Superconducting Shield

This article relates generally to magnetic shields and more particularly to a superconducting shield having a composition gradient which is capable of providing a low magnetic field environment. The figure shows a cross-sectional view of a cryostat 1 immersed in a container (not shown) of liquid helium. The cryostat holds an exchange gas which is utilized to cool a superconducting shield
2. Shield 2 is comprised of a superconducting material which has a composition gradient which varies from the bottom of shield 2 to its top. As a result of the composition gradient, the Tc for the normal-superconducting transition of the material also varies along shield 2. The composition gradient insures that a shield, which is cooled uniformly, passes into the superconducting state in a smooth fashion following the material gradient. Magnetic field is then excluded from the body of the shield (Meissner effect). The essential element is the composition gradient which controls the sequence in which the regions of shield 2 go superconducting upon uniform cooling of the device. Shield 2 may be composed of Nb3Snx-x(A-15) wherein the fraction of tin (x) in shield 2 determines the local value of Tc . Shield 2 may be fabricated by plating a smoothly varying layer of tin along the length of a niobium shield by pulling the shield slowly out of a plating solution. Shield 2 is then heated at 650OEC for 24 hours, forming the A-15 compound and smoothing out any...