Cryogenic current comparators with optimum SQUID readout for current and resistance quantum metrology

María Elena Bartolomé Porcar

Research output: ThesisPhD Thesis - Research UT, graduation UT

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Abstract

This thesis describes the development of several systems based on the Cryogenic Current Comparator with optimum SQUID readout, for current and resistance metrology applications. the CCC-SQUID is at present the most accurate current comparator available. A (type I) CCC consists basically of a superconducting tube containing two sets of windings N1 and N2, carrying the two currents I1 and I2 to be compared. As a result of the Meissner effect, a screening current equal to (I2N2-I1N1) circulates in the tube (overlapped “like a snake swallowing its own tail” to shield the windings from the sensing circuit). The flux associated to the unbalance current is coupled to a SQUID, the most sensitive flux sensor available nowadays. The SQUID is basically a superconducting ring interrupted by one (rf SQUID) or two (dc SQUID) weak links called Josephson junctions. The device works basically as a flux-to-voltage converter.
Original languageEnglish
Awarding Institution
  • University of Twente
Supervisors/Advisors
  • Rogalla, Horst, Supervisor
  • Flokstra, J., Supervisor
Award date1 Mar 2002
Place of PublicationEnschede
Publisher
Print ISBNs9789036517010
Publication statusPublished - 1 Mar 2002

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