The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 25, 1987
Filed:
Nov. 13, 1984
Roger N Hastings, Burnsville, MN (US);
Gerald F Sauter, Eagan, MN (US);
George F Nelson, Coon Rapids, MN (US);
Sperry Corporation, Blue Bell, PA (US);
Abstract
A SQUID, nominally of the 'hybrid' type, wherein the normally superconducting modulation coil is modified to instead be a non-superconducting material, nominally manginin, exhibits reduced long-term, or d.c., thermal response. When an alternating current waveform--rising to a nominal 130 ma. r.m.s. amplitude within a nominal 0.5 seconds and, after a nominal 100 msec. to 20 sec. duration, returning to 0 within a nominal 0.1 sec--is applied to the non-superconducting modulation coil of such a SQUID at superconducting temperature then the entire SQUID thermal response, particularly including the short-term, or a.c., SQUID thermal response, is thereafter reducible to essentially 0. The process is hypothesized to 'deflux' the SQUIDs of fluxons trapped during the cool-down of superconductor within the SQUID and associated circuitry. The optimal 'de-fluxing' alternating current waveform for any individual SQUID is empirically derivable. Once 'de-fluxed' a SQUID maintains a uniformly reduced thermal response for so long as it remains superconducting. SQUIDs may be repetitively initialized/reinitialized by 'defluxing' without damage to the SQUID or diminishment of the effective reduction/elimination of thermal response.