Optimum sensitivity of an externally shielded cryogenic current comparator

Author

Early, Murray D. ; Jones, Keith

Author_Institution

Meas. Standards Lab., New Zealand

Volume

46

Issue

2

fYear

1997

fDate

4/1/1997 12:00:00 AM

Firstpage

459

Lastpage

462

Abstract

The sensitivity of an overlapped-tube cryogenic current comparator (CCC) has been calculated including the effect of a cylindrical external shield. Dimensions of the shield, tube and pick-up coil can be optimized to give maximum sensitivity. The sensitivity in the case of a fixed radius shield has been numerically investigated and a CCC based on an optimized design has been constructed. A single sensitivity measurement indicates that the cylindrical-shield model is accurate to within about 20% of the measured value. This is a significant improvement compared with a simplified ring model of the shield or neglecting the shield entirely

Keywords

SQUIDs; bridge instruments; coils; cryogenics; current comparators; quantum Hall effect; shielding; cylindrical external shield; cylindrical-shield model; externally shielded cryogenic current comparator; fixed radius shield; pick-up coil; quantum Hall resistance bridges; sensitivity measurement; Cryogenics; Design optimization; Electrical resistance measurement; Equations; Equivalent circuits; Geometry; Inductance; Superconducting coils; Superconducting epitaxial layers; Wire;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/19.571884

Filename

571884