Overview of MgB<sub>2</sub> Superconductor Applications

Tomsic, M.; Rindfleisch, M.; Yue, J.; McFadden, Kevin; Phillips, J. L.; Sumption, M.D.; Bhatia, M.; Bohnenstiehl, S.; Collings, E. W.

doi:10.1111/j.1744-7402.2007.02138.x

Cited by 136 publications

(106 citation statements)

References 16 publications

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“…Magnesium diboride (MgB 2 ), which was found to be superconducting in 2001 [2], is considered as a promising candidate for LHe-free operation in MRI due to its relatively low material and fabrication costs compared to high temperature superconductors. In addition, its transition temperature of 39 K allows it to operate at higher temperatures up to 25 K [3][4][5][6]. Owing to these benefits [7,8], there have been many recent reports on MgB 2 -conductor-based MRI magnets [9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

MgB₂superconducting joints for persistent current operation

Patel

Hossain

See

et al. 2015

Supercond. Sci. Technol.

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High-performance superconducting joints are essential for realizing persistent-mode magnets. Herein, we propose a concept and fabrication of such superconducting joints, which yielded reliable performance in the operating temperature range of 4.2-25 K. MgB 2 -MgB 2 joints in magnets are known to result in deterioration of localized electrical, thermal, and mechanical properties. To overcome these problems, the ends of the two wires are inserted into a pellet press, which is then filled with a mixture of unreacted magnesium and boron powders, followed by heat treatment. The critical current capacity and joint resistance were precisely evaluated by the standard four-probe method in open-circuit and by field-decay measurements in a closed-loop, respectively. These joints demonstrated up to 66% of the current-carrying capacity of unjoined wire at 20 K, 2 T and joint resistance of 1.4 x 10 −12 Ω at 4.2 K in self-field. AbstractHigh-performance superconducting joints are essential for realizing persistent-mode magnets.Herein, we propose a new process and fabrication of such superconducting joints, which yielded reliable performance in the operating temperature range of 4.2 K to 25 K. MgB 2 -MgB 2 joints in magnets, are known to result in deterioration of localized electrical, thermal, and mechanical properties. To overcome these problems, the ends of the two wires are inserted into a pellet press, which is then filled with a mixture of unreacted magnesium and boron powders, followed by heat treatment. The critical current capacity and joint resistance were precisely evaluated by the standard four-probe method in open-circuit and by fielddecay measurements in a closed-loop, respectively. These joints demonstrated up to 66% of the current-carrying capacity of unjoined wire at 20 K, 2 T and joint resistance of < 1.4 x 10 -12 Ω at 4.2 K in self-field.

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Section: Introductionmentioning

confidence: 99%

MgB₂superconducting joints for persistent current operation

Patel

Hossain

See

et al. 2015

Supercond. Sci. Technol.

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“…Wires were made at Hyper Tech Research using a continuous tube forming and filling (CTFF) process [15]. The MgB 2 wires comprised of amorphous B (99B) with a Mg to B ratio of 1.1:2, Nb barrier and eighteen filaments.…”

Section: Preparation Of Samplesmentioning

confidence: 99%

Evidence of Point Pinning Centers in Un-Doped Mgb2 Wires at 20 K after HIP Process

Gajda¹,

Morawski²,

Zaleski³

et al. 2016

J Material Sci Eng

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In this paper we present results of transport critical current density (J c ) at 20 K and 4.2 K, irreversible magnetic field (B irr ), upper critical field (B c2 ), critical temperature (T c ), pinning force (F p ), scanning pinning force scaling results (F p /F pmax and B/B irr ) and electron microscope (SEM) images of un-doped MgB 2 wires of 0.63 mm diameter. All wires were annealed at pressures ranging from 0.1 MPa to 1 GPa for 15 min between 680°C to 740°C. SEM images show that 1 GPa pressure yields small grains, higher MgB 2 material density, and small voids. The results obtained by a physical properties measurement system (PPMS) show that high pressure (1 GPa) and 700°C annealing slightly decreases T c above 27 K and increases T c and B irr below 25 K. Un-doped MgB 2 wire annealed in 1 GPa for 15 min at 680°C at has a 20 K, 4.5 T J c of 100 A/mm 2 in and a B irr of 7 T. At 4.2 K, this wire has J c of 100 A/mm 2 at 10.5 T. Scaling results show that the dominant pinning mechanism is point pinning for undoped MgB 2 wires under 1 GPa pressure and annealed at 680°C (at 20 K).

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“…4). Studies indicate that oxygen can create precipitation of MgO [6,9,18]. This precipitation can create surface or point (thickness close to the coherence length) pinning centers.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, MgB 2 wires are made from Mg particles, which are much larger than B particles [9]. This indicates that the structure of the MgB 2 material depends mainly on the Mg particle size.…”

Section: Introductionmentioning

confidence: 99%

Formation of High-Field Pinning Centers in Superconducting MgB2 Wires by Using High Hot Isostatic Pressure Process

Gajda

Morawski

Zaleski

et al. 2017

J Supercond Nov Magn

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This paper demonstrates the effects of hot isostatic pressure (HIP) on the structure and transport critical parameters of in situ MgB 2 wires without a barrier. Our results show that only HIP and nano-boron allow the formation of more high-field pinning centers, which lead to the increase in critical current density (J c ) at high applied magnetic fields. Nano-boron and annealing at a low pressure increase the J c in the low magnetic field. This indicates that nano-particles create more high-field pinning centers. In addition, the results show that nano-boron improves the connection between the grains. Scanning electron microscope results show that HIP increases the reaction rate between Mg and B, density, and homogeneity of the MgB 2 material. Additionally, HIP allows to create a structure with small grains and voids and eliminates the significance of the number of voids. High isostatic pressure allows to obtain high J c of 10 A/mm 2 (at 4.2 K) in 10 T and increases irreversible magnetic field (B irr ) and upper critical field (B c2 Measurements show that these wires have high critical temperature of 37 K.

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Overview of MgB₂ Superconductor Applications

Cited by 136 publications

References 16 publications

MgB₂superconducting joints for persistent current operation

MgB₂superconducting joints for persistent current operation

Evidence of Point Pinning Centers in Un-Doped Mgb2 Wires at 20 K after HIP Process

Formation of High-Field Pinning Centers in Superconducting MgB2 Wires by Using High Hot Isostatic Pressure Process

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Overview of MgB2 Superconductor Applications

Cited by 136 publications

References 16 publications

MgB2superconducting joints for persistent current operation

MgB2superconducting joints for persistent current operation

Evidence of Point Pinning Centers in Un-Doped Mgb2 Wires at 20 K after HIP Process

Formation of High-Field Pinning Centers in Superconducting MgB2 Wires by Using High Hot Isostatic Pressure Process

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Product

Resources

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Overview of MgB₂ Superconductor Applications

MgB₂superconducting joints for persistent current operation

MgB₂superconducting joints for persistent current operation