AC Defluxing of SQUIDs

Andrei N. Matlashov; Vasili K. Semenov; William H. Anderson

doi:10.1109/TASC.2017.2650902

AC Defluxing of SQUIDs

Andrei N. Matlashov
, Vasili K. Semenov
, William H. Anderson

Physics and Astronomy

Los Alamos National Laboratory
SENIOR SCIENTIFIC

Research output: Contribution to journal › Article › peer-review

4 Scopus citations

Abstract

Magnetic flux trapping is a very serious problem in SQUID-based instrumentation and superconducting electronics. A critical consideration for avoiding flux trapping is a prevention of SQUID sensors or circuits from being exposed to magnetic fields. Unfortunately, this measure cannot be applied, if sensors must be exposed to a strong magnetic field or transients. For example, unavoidable exposures take place in ultralow field magnetic resonance imaging and superparamagnetic relaxation measurements using unshielded thin-film planar SQUID sensors. SQUID sensors stop working after being exposed to magnetic fields of only a few mT in strength. Earlier, we reported successful results of defluxing of planar LTS SQUID-gradiometers using strong decaying ac magnetic pulses. In this paper, we present further experimental results and discuss a possible mechanism to explain the observed defluxing effects. The new ac defluxing technique is much faster and dissipates much less energy than a conventional thermal cycling.

Original language	English
Article number	7812581
Journal	IEEE Transactions on Applied Superconductivity
Volume	27
Issue number	4
DOIs	https://doi.org/10.1109/TASC.2017.2650902
State	Published - Jun 2017

Keywords

de-fluxing
Flux trapping
pinning
planar gradiometers
thermal cycling
thin-film SQUIDs

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10.1109/TASC.2017.2650902

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title = "AC Defluxing of SQUIDs",

abstract = "Magnetic flux trapping is a very serious problem in SQUID-based instrumentation and superconducting electronics. A critical consideration for avoiding flux trapping is a prevention of SQUID sensors or circuits from being exposed to magnetic fields. Unfortunately, this measure cannot be applied, if sensors must be exposed to a strong magnetic field or transients. For example, unavoidable exposures take place in ultralow field magnetic resonance imaging and superparamagnetic relaxation measurements using unshielded thin-film planar SQUID sensors. SQUID sensors stop working after being exposed to magnetic fields of only a few mT in strength. Earlier, we reported successful results of defluxing of planar LTS SQUID-gradiometers using strong decaying ac magnetic pulses. In this paper, we present further experimental results and discuss a possible mechanism to explain the observed defluxing effects. The new ac defluxing technique is much faster and dissipates much less energy than a conventional thermal cycling.",

keywords = "de-fluxing, Flux trapping, pinning, planar gradiometers, thermal cycling, thin-film SQUIDs",

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journal = "IEEE Transactions on Applied Superconductivity",

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T1 - AC Defluxing of SQUIDs

AU - Matlashov, Andrei N.

AU - Semenov, Vasili K.

AU - Anderson, William H.

PY - 2017/6

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N2 - Magnetic flux trapping is a very serious problem in SQUID-based instrumentation and superconducting electronics. A critical consideration for avoiding flux trapping is a prevention of SQUID sensors or circuits from being exposed to magnetic fields. Unfortunately, this measure cannot be applied, if sensors must be exposed to a strong magnetic field or transients. For example, unavoidable exposures take place in ultralow field magnetic resonance imaging and superparamagnetic relaxation measurements using unshielded thin-film planar SQUID sensors. SQUID sensors stop working after being exposed to magnetic fields of only a few mT in strength. Earlier, we reported successful results of defluxing of planar LTS SQUID-gradiometers using strong decaying ac magnetic pulses. In this paper, we present further experimental results and discuss a possible mechanism to explain the observed defluxing effects. The new ac defluxing technique is much faster and dissipates much less energy than a conventional thermal cycling.

AB - Magnetic flux trapping is a very serious problem in SQUID-based instrumentation and superconducting electronics. A critical consideration for avoiding flux trapping is a prevention of SQUID sensors or circuits from being exposed to magnetic fields. Unfortunately, this measure cannot be applied, if sensors must be exposed to a strong magnetic field or transients. For example, unavoidable exposures take place in ultralow field magnetic resonance imaging and superparamagnetic relaxation measurements using unshielded thin-film planar SQUID sensors. SQUID sensors stop working after being exposed to magnetic fields of only a few mT in strength. Earlier, we reported successful results of defluxing of planar LTS SQUID-gradiometers using strong decaying ac magnetic pulses. In this paper, we present further experimental results and discuss a possible mechanism to explain the observed defluxing effects. The new ac defluxing technique is much faster and dissipates much less energy than a conventional thermal cycling.

KW - de-fluxing

KW - Flux trapping

KW - pinning

KW - planar gradiometers

KW - thermal cycling

KW - thin-film SQUIDs

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DO - 10.1109/TASC.2017.2650902

M3 - Article

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JO - IEEE Transactions on Applied Superconductivity

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ER -

AC Defluxing of SQUIDs

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Keywords

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