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

Ahn, Min Cheol; Yagai, Tsuyoshi; Hahn, Seungyong; Ando, Ryo; Bascuñán, J.; Iwasa, Y.

doi:10.1109/tasc.2009.2018102

Cited by 63 publications

(19 citation statements)

References 8 publications

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“…Table III summarizes key parameters of H600-54 and new six NI HTS inserts with a 1 H NMR frequency of 600, 700, or 800 MHz and an RT bore of either 54 or 60 mm. Those inserts with a 60-mm RT bore are designed to accommodate extra shim sets to mitigate large field impurities of screening-cur-rent-induced fields [8], [9]. Design focuses are to: 1) limit the overall hoop strain to less than 0.5% and 0.4% for YBCO and Bi2223 coils respectively, though the maximum tensile strain limits are 0.6% for YBCO and 0.45% for Bi2223 [7]; 2) set a radial gap of 26 mm between the inner coil and the RT bore (20 mm in HT600–54) for improved cryogenics; 3) set an operating current, I op , 180–210 A, less than the 251 A of H600–54.…”

Section: Design Of No-insulation Hts Insertsmentioning

confidence: 99%

No-Insulation (NI) HTS Inserts for $>$1 GHz LTS/HTS NMR Magnets

Hahn

Park

Voccio

et al. 2012

IEEE Trans. Appl. Supercond.

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A no-insulation (NI) technique has been applied to wind and test a NI HTS (YBCO) double-pancake coil at 4.2 K. Having little detrimental effect on field-current relationship, the absence of turn-to-turn insulation enabled the test coil to survive a quench at a coil current density of 1.58. The NI HTS coil is compact and self-protecting, two features suitable for large highfield magnets. To investigate beneficial impacts of the NI technique on 1 GHz LTS/HTS NMR magnets, we have designed six new NI HTS inserts for our ongoing 1.3 GHz LTS/HTS NMR magnet, which require less costly LTS background magnets than the original insulated HTS insert. A net result will be a significant reduction in the overall cost of an LTS/HTS NMR magnet, at 1.3 GHz and above.

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Section: Design Of No-insulation Hts Insertsmentioning

confidence: 99%

No-Insulation (NI) HTS Inserts for $>$1 GHz LTS/HTS NMR Magnets

Hahn

Park

Voccio

et al. 2012

IEEE Trans. Appl. Supercond.

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“…It is known that the screening currents in NMR with inserts made of HTS tape may significantly degrade NMR performance [18], [19]. …”

Section: Conductor Requirements Challenges and Opportunitiesmentioning

confidence: 99%

Conductors for commercial MRI magnets beyond NbTi: requirements and challenges

Parizh

Lvovsky

Sumption

2016

Supercond. Sci. Technol.

124

107

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Magnetic Resonance Imaging (MRI), a powerful medical diagnostic tool, is the largest commercial application of superconductivity. The superconducting magnet is the largest and most expensive component of an MRI system. The magnet configuration is determined by competing requirements including optimized functional performance, patient comfort, ease of siting in a hospital environment, minimum acquisition and lifecycle cost including service. In this paper, we analyze conductor requirements for commercial MRI magnets beyond traditional NbTi conductors, while avoiding links to a particular magnet configuration or design decisions. Potential conductor candidates include MgB2, ReBCO and BSCCO options. The analysis shows that no MRI-ready non-NbTi conductor is commercially available at the moment. For some conductors, MRI specifications will be difficult to achieve in principle. For others, cost is a key barrier. In some cases, the prospects for developing an MRI-ready conductor are more favorable, but significant developments are still needed. The key needs include the development of, or significant improvements in: (a) conductors specifically designed for MRI applications, with form-fit-and-function readily integratable into the present MRI magnet technology with minimum modifications. Preferably, similar conductors should be available from multiple vendors; (b) conductors with improved quench characteristics, i.e. the ability to carry significant current without damage while in the resistive state; (c) insulation which is compatible with manufacturing and refrigeration technologies; (d) dramatic increases in production and long-length quality control, including large-volume conductor manufacturing technology. In-situ MgB2 is, perhaps, the closest to meeting commercial and technical requirements to become suitable for commercial MRI. Conductor technology is an important, but not the only, issue in introduction of HTS / MgB2 conductor into commercial MRI magnets. These new conductors, even when they meet the above requirements, will likely require numerous modifications and developments in the associated magnet technology.

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“…High-resolution, > 1-GHz NMR magnets, such as our 1.3-GHz NMR, must have an all-HTS insert; however one of the nuisances of REBCO coils is the effect of the screening current field (SCF). The SCF not only causes the central magnetic field to drift with time but it has also been demonstrated that SCF-induced error fields degrade spatial field homogeneity [12]–[15]. It has also been demonstrated that SCF reduces the central magnetic field [16]–[18].…”

Section: Shaking Coil Magnetmentioning

confidence: 99%

An 800-MHz all-REBCO Insert for the 1.3-GHz LTS/HTS NMR Magnet Program—A Progress Report

Bascuñán

Hahn

Lécrevisse

et al. 2016

IEEE Trans. Appl. Supercond.

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A critical component of the 1.3-GHz nuclear magnetic resonance magnet (1.3 G) program, currently ongoing at the Francis Bitter Magnet Laboratory, Plasma Science and Fusion Center, Massachusetts Institute of Technology, and now approaching its final stage, is the all high-temperature superconductor 800-MHz insert (H800). The insert consists of three nested double-pancake (DP) coils fabricated with 6-mm-wide REBCO conductor. Coil 1, the innermost coil of H800, has already been fabricated and tested at 77 and 4.2 K. In addition, one third of the DPs for Coil 2 have been wound and each DP individually fully tested. Work described here includes details of Coil 1 fabrication: DP winding, DP testing, assembling, joint performance, overbanding, and coil testing; winding details of DPs for Coil 2 and their testing are also included.

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

Cited by 63 publications

References 8 publications

No-Insulation (NI) HTS Inserts for $>$1 GHz LTS/HTS NMR Magnets

No-Insulation (NI) HTS Inserts for $>$1 GHz LTS/HTS NMR Magnets

Conductors for commercial MRI magnets beyond NbTi: requirements and challenges

An 800-MHz all-REBCO Insert for the 1.3-GHz LTS/HTS NMR Magnet Program—A Progress Report

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