Method and apparatus of implementing a magnetic shield flux sweeper

Patent metadata

Field	Value
Publication number	US-9913414-B2
Application number	US-201514846498-A
Country	US
Kind code	B2
Filing date	Sep 4, 2015
Priority date	Sep 4, 2015
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

The present invention relates to a method and apparatus of protecting magnetically sensitive devices with a shield, including: a non-superconducting metal or lower transition temperature (T c ) material compared to a higher transition temperature material, disposed in a magnetic field; means for creating a spatially varying order parameter's |Ψ(r,T)| 2 in a non-superconducting metal or a lower transition temperature material; wherein a spatially varying order parameter is created by a proximity effect, such that the non-superconducting metal or the lower transition temperature material becomes superconductive as a temperature is lowered, creating a flux-free Meissner state at a center thereof, in order to sweep magnetic flux lines to the periphery.

First claim

What is claimed is:

1. A shield which protects magnetically sensitive devices, the shield comprising:
a non-superconducting metal or lower transition temperature (T c ) material compared to a higher transition temperature material, disposed in a magnetic field environment;
a temperature control system to cool the non-superconducting metal or lower transition temperature (T c ) material below its transition temperature to create a spatially varying order parameter's |Ψ(r,T)| 2 in said non-superconducting metal or said lower transition temperature material, where Ψ is the superconductivity order parameter, r is a spatial position, and T is temperature;
wherein said spatially varying order parameter is created by a proximity effect, such that said non-superconducting metal or said lower transition temperature material becomes superconductive as a temperature is lowered, creating a flux-free Meissner state, in order to sweep magnetic flux lines to a periphery of said non-superconducting metal or said lower transition temperature material.

2. The shield of claim 1 , wherein said proximity effect is one of a variable thickness proximity effect, a longitudinal proximity effect, an inverse proximity effect, or combination thereof.

3. The shield of claim 2 , the shield further comprising:
a higher transition temperature (T c ) superconducting material disposed on said non-superconducting metal or said lower transition temperature (T c ) material.

4. The shield of claim 3 , wherein said higher transition temperature superconducting material is disposed in a plurality of different patterns on said non-superconducting metal or said lower transition temperature (T c ) material.

5. The shield of claim 4 , wherein the shield is provided in a plurality of heterostructure two-dimensional and three-dimensional structures, including planar and non-planar structures.

6. The shield of claim 5 , wherein the shield comprises a planar disc or a cylinder.

7. The shield of claim 6 , the shield further comprising:
a highest transition temperature (T c ) superconducting material;
wherein said non-superconducting metal or said lower transition temperature material and said higher transition temperature material form a bilayer; and
wherein said highest transition temperature superconducting material is disposed on said bilayer.

8. The shield of claim 7 , wherein said proximity effect is a combination of said longitudinal proximity effect and said variable thickness proximity effect.

9. The shield of claim 6 , wherein the shield is said cylinder; and
wherein said higher transition temperature material is provided in a strip with a width less than a critical length.

10. The shield of claim 6 , wherein said cylinder is open-ended, and said planar disc is provided at one end of said open-ended cylinder.

11. The shield of claim 10 , the shield further comprising:
an intermediate transition temperature superconducting material, said intermediate transition temperature superconducting material having a transition temperature between said higher transition temperature superconducting material and said non-superconducting metal; and
wherein said planar disc comprises said higher transition temperature superconducting material disposed in said plurality of different patterns on one of said intermediate transition temperature superconducting material, or a bilayer of said non-superconducting metal and a superconducting material.

12. The shield of claim 11 , wherein sides of said open-ended cylinder are comprised of said intermediate transition temperature superconducting material, and said non-superconducting metal or said lower transition temperature (T c ) material in a variable thickness; and
wherein said magnetic flux lines are swept outwards from said center of said planar disc to a perimeter of said planar disc, and from a top of said open-ended cylinder where said planar disc is disposed, to a bottom of said open-ended cylinder.

13. The shield of claim 6 , wherein said planar disc comprises said higher transition temperature superconducting material disposed in said plurality of different patterns on a bilayer of said non-superconducting metal and a superconducting material; and
wherein a superconducting lead is connected to one of said non-superconducting metal or said higher transition temperature superconducting material at each of two ends thereof.

14. The shield of claim 13 , the shield further comprising:
a metal bank structure deposited on at least said non-superconducting metal;
wherein said metal bank structure comprises gold.

15. The shield of claim 14 , wherein said non-superconducting metal is gold and said higher transition temperature superconducting material is molybdenum; and
wherein said superconducting lead comprises niobium.

16. The shield of claim 13 , wherein said plurality of different patterns includes another superconducting lead disposed at a center of said planar disc at a greater thickness than at edges thereof, and allows for tuning of the shield; or
wherein said superconducting lead is disposed at edges of said metal bank structure and separately at said center of said planar disc.

17. The shield of claim 4 , wherein trapping regions are disposed at edges of said at least one of said non-superconducting metal or said higher transition temperature superconducting material.

18. The shield of claim 13 , the shield further comprising:
an insulator layer on which said higher transition temperature material is disposed; and
a metal layer ground plane on which said insulator layer is disposed; and
a superconductor disposed at edges of said metal layer ground plane.

19. An array of sensors comprising a plurality of shields of claim 1 .

20. The array of claim 19 , the array further comprising:
a magnetometer disposed in the array;
a continuous superconducting loop around the array; and
a compensating magnetic field coil disposed around the array.

21. A method of protecting a magnetically sensitive device, the method comprising:
creating a spatially varying order parameter's |Ψ(r,T)| 2 in a non-superconducting metal or a lower transition temperature (T c ) material compared to a higher transition temperature material, said non-superconducting metal or said lower transition temperature material being disposed in a magnetic field, where Ψ is the superconductivity order parameter, r is a spatial position, and T is temperature;
wherein said spatially varying order parameter is created by a proximity effect, such that said non-superconducting metal or said lower transition temperature material becomes superconductive as a temperature is lowered, creating a flux-free Meissner state, in order to sweep magnetic flux lines to a periphery of said non-superconducting metal or said lower transition temperature material.

22. An electrical lead of a cryogenic detector, the lead comprising:
a magnetic flux sweeper which uses a proximity effect to create spatially varying order parameter's |Ψ(r,T)| 2 such that upon cooling, the electrical lead becomes superconductive and magnetic flux lines are swept to a periphery creating a flux-free Meissner state in said electrical lead which carries current to and from the cryogenic detector, where Ψ is the superconductivity order parameter, r is a spatial position, and T is temperature.

23. A sensing element of a cryogenic detector comprising:
a magnetic flux sweeper which uses a proximity effect to create sp

Assignees

• Nasa

Inventors

• Sadleir John E

Classifications

• G01R33/025

  Compensating stray fields {(G01R33/0017 takes precedence)} · CPC title

• G01R33/0076

  Protection, e.g. with housings against stray fields · CPC title

• H05K9/0077 Primary

  comprising superconductors · CPC title