Spatial and Temporal Variations of a Screening Current Induced Magnetic Field in a Double-Pancake HTS Insert of an LTS/HTS NMR Magnet.

IEEE transactions on applied superconductivity : a publication of the IEEE Superconductivity Committee · 2009 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 3325

Study snapshot

PublicationIEEE transactions on applied superconductivity : a publication of the IEEE Superconductivity Committee · 2009

Study typeengineering

Reported directionUnclear

Evidence ratingInsufficient

Abstract

This paper presents experimental and simulation results of a screening current induced magnetic field (SCF) in a high temperature superconductor (HTS) insert that constitutes a low-/high-temperature superconductor (LTS/HTS) NMR magnet. In this experiment, the HTS insert, a stack of 50 double-pancake coils, each wound with Bi2223 tape, was operated at 77 K. A screening current was induced in the HTS insert by three magnetic field sources: 1) a self field from the HTS insert; 2) an external field from a 5-T background magnet; and 3) combinations of 1) and 2). For each field excitation, which induced an SCF, its axial field distribution and temporal variations were measured and compared with simulation results based on the critical state model. Agreement on field profile between experiment and simulation is satisfactory but more work is needed to make the simulation useful for designing shim coils that will cancel the SCF.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeengineering

Effect directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureNot supplied

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

Experimental measurements and simulations (critical state model) of the screening current induced magnetic field (SCF) in a Bi2223-tape HTS insert operated at 77 K were compared under self-field, external 5-T background field, and combined excitations. Agreement between experiment and simulation for the field profile was reported as satisfactory, though additional work was noted as needed to make simulations useful for designing shim coils to cancel SCF.

Outcomes measured

Axial field distribution of screening current induced magnetic field (SCF)
Temporal variations of SCF
Agreement between experimental measurements and critical state model simulations

Limitations

More work needed to make the simulation useful for designing shim coils that will cancel the SCF
No health/biological outcomes reported

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": null,
    "source": "NMR magnet (LTS/HTS) / background magnet",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Axial field distribution of screening current induced magnetic field (SCF)",
    "Temporal variations of SCF",
    "Agreement between experimental measurements and critical state model simulations"
  ],
  "main_findings": "Experimental measurements and simulations (critical state model) of the screening current induced magnetic field (SCF) in a Bi2223-tape HTS insert operated at 77 K were compared under self-field, external 5-T background field, and combined excitations. Agreement between experiment and simulation for the field profile was reported as satisfactory, though additional work was noted as needed to make simulations useful for designing shim coils to cancel SCF.",
  "effect_direction": "unclear",
  "limitations": [
    "More work needed to make the simulation useful for designing shim coils that will cancel the SCF",
    "No health/biological outcomes reported"
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "screening current induced magnetic field",
    "SCF",
    "high temperature superconductor",
    "HTS insert",
    "LTS/HTS NMR magnet",
    "double-pancake coils",
    "Bi2223 tape",
    "77 K",
    "5-T background magnet",
    "critical state model",
    "shim coils"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1109/tasc.2009.2018102
PubMed: 20401187

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