Title :
Cryogenic current comparator measurements at 77 K using thallium-2223 thick-film shields
Author_Institution :
Nat. Inst. of Stand. & Technol., Gaithersburg, MD, USA
fDate :
4/1/1999 12:00:00 AM
Abstract :
Several different magnetic shield geometries were used to study cryogenic current comparator (CCC) operation with thallium-based thick film superconducting shields at 77 K. These shields are found to have good magnetic shielding properties and to support low-level persistent currents. This study investigates geometric properties of the magnetic coupling between the CCC and one type of superconducting quantum interference device (SQUID) sensor. The sensitivity of the SQUID and its coupling to the shielding currents limit ten-to-one CCC resistance ratio measurements to approximately 0.2 μΩ/Ω in relative uncertainty
Keywords :
SQUID magnetometers; barium compounds; bridge circuits; calcium compounds; current comparators; electric resistance measurement; high-temperature superconductors; magnetic shielding; superconducting coils; thallium compounds; 77 K; HTSC shields; SQUID sensor; TlBaCaCuO; cryogenic current comparator measurements; geometric properties; low-level persistent currents; magnetic coupling; magnetic shield geometries; relative uncertainty; resistance ratio measurements; sensitivity; superconducting shields; thallium-2223 thick-film shields; Cryogenics; Current measurement; Geometry; Magnetic properties; Magnetic shielding; Persistent currents; SQUIDs; Superconducting films; Superconducting magnets; Thick films;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
