Development of a split-toroid high-temperature superconducting cryogenic current comparator

Author

Early, Murray D. ; Jones, Keith ; Staines, Mike P. ; Exley, Ross R.

Author_Institution

Meas. Standards Lab. of New Zealand, Ind. Res. Ltd., Lower Hutt, New Zealand

Volume

50

Issue

2

fYear

2001

fDate

4/1/2001 12:00:00 AM

Firstpage

306

Lastpage

309

Abstract

Cryogenic current comparators (CCCs) based on split toroidal shields show promise for the construction of high-accuracy ratio devices using high-temperature superconductors. To test this approach we have carried out measurements on a low-temperature superconducting prototype built of three layers of toroidal shields. We find that ratio accuracies of about 1 in 10⁷ are achievable for this prototype. After several attempts, we were also able to construct a toroidal two-layer CCC fabricated of YBCO (YBa₂Cu₃O₇) components using split shields. The results from measurements on this device at low temperatures (4 K) indicate that the shielding provided by these layers does not provide sufficient attenuation of the leakage flux. The challenge remains to find a processing technique to produce YBCO in a machinable form with satisfactory magnetic shielding properties

Keywords

cryogenic electronics; cryogenics; current comparators; electric current measurement; high-temperature superconductors; magnetic shielding; measurement standards; YBa₂Zn₃O₇; attenuation; cryogenic current comparators; high-accuracy ratio devices; high-temperature superconductors; leakage flux; magnetic shielding properties; processing technique; ratio accuracies; split toroidal shields; Cryogenics; Current measurement; Electrical resistance measurement; High temperature superconductors; Laboratories; Prototypes; SQUIDs; Superconducting epitaxial layers; Superconducting materials; Yttrium barium copper oxide;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/19.918128

Filename

918128