US 5,329,165 A · Selectively switchable superconducting electromagnetic shield

Abstract

A selectively controllable, direction-, amplitude- and/or frequency-specific superconducting shield (10) is provided which includes a multiply-connected superconducting shield (12) adapted to shield a zone (13) from external magnetic, electric and/or electromagnetic fields and signals. Controlled gating of the shield (12) is provided by means (16) serving to selectively lower the critical shielding current density of a portion (26) of the shield (12) to a level permitting entrance of external fields through the portion (26), while leaving the critical shielding current densities of other portions of the shield (12) at higher, field-shielding levels. The means (16) preferably includes respective, selectively energizable coil pairs (CP.sub.1, CP.sub.2 . . . CP.sub.n) disposed about the shield (12). A highly sensitive magnetic detector (30) would include the shielding device (10) as well as a SQUID assembly (18) situated within the zone (13) defined by shield (12). The detectors of the invention may be used in passive, gating-controlled arrays in order to improve signal discrimination and signal-to-noise characteristics of conventional arrays.

Claims25

Dependent claims

Apparatus for selectively shielding a zone from external fields comprising magnetic, electric or electromagnetic fields, said apparatus comprising:

a multiply-connected body formed of superconducting material having characteristic critical temperature and critical shielding current density values, said body being disposed about said zone and operable at a temperature below the critical temperature of the material for shielding said zone from said fields;
and
means for selectively lowering the critical shielding current density of a portion of said body to a level permitting entrance of external fields through said portion, while leaving the critical shielding current density of another portion of said body at a higher, field-shielding level.

A method for detecting a desired field selected from the group consisting of magnetic, electric and electromagnetic fields, and discriminating undesired fields, said method comprising the steps of:

providing a detector for said desired field;
shielding said detector from said desired and undesired fields by locating a shield for said desired and undesired fields between the sources thereof and said detector;
and
selectively eliminating a first portion of said shield while leaving other portions of the shield in place in order to permit entrance of said desired field through said first portion in order to permit detection of said desired field by said detector, while preventing entrance of said undesired fields through said other portions.

1 more element

Dependencies are inferred from the claim text.

Selectively switchable superconducting electromagnetic shield

Life of this patent

Selectively switchable superconducting electromagnetic shield

Life of this patent

Abstract

Claims25