A proof-of-concept Bitter-like HTS electromagnet fabricated from a silver-infiltrated (RE)BCO ceramic bulk

TY - JOUR

T1 - A proof-of-concept Bitter-like HTS electromagnet fabricated from a silver-infiltrated (RE)BCO ceramic bulk

AU - Taylor, R. W.

AU - Weijers, H. W.

AU - Ainslie, M. D.

AU - Congreve, J. V. J.

AU - Durrell, J. H.

AU - Badcock, R. A.

AU - Bumby, Chris W.

N1 - Funding Information: Financial support for this work came from NZ Marsden Grant MFP-VUW1806, and NZ Ministry of Business, Innovation and Employment’s SSIF AETP Contract RTVU2004. Publisher Copyright: © 2024 The Author(s). Published by IOP Publishing Ltd.

PY - 2024/3

Y1 - 2024/3

N2 - A novel concept for a compact high-field magnet coil is introduced. This is based on stacking slit annular discs cut from bulk rare-earth barium cuprate ((RE)BCO) ceramic in a Bitter-like architecture. Finite-element modelling shows that a small 20 turn stack (with a total coil volume of < 20 cm 3) is capable of generating a central bore magnetic field of > 2 T at 77 K and > 20 T at 30 K. Unlike resistive Bitter magnets, the high-temperature superconducting (HTS) Bitter stack exhibits significant non-linear field behaviour during current ramping, caused by current filling proceeding from the inner radius outwards in each HTS layer. Practical proof-of-concept for this architecture was then demonstrated through fabricating an uninsulated four-turn prototype coil stack and operating this at 77 K. A maximum central field of 0.382 T was measured at 1.2 kA, with an accompanying 6.1 W of internal heat dissipation within the coil. Strong magnetic hysteresis behaviour was observed within the prototype coil, with ≈30% of the maximum central field still remaining trapped 45 min after the current had been removed. The coil was thermally stable during a 15 min hold at 1 kA, and survived thermal cycling to room temperature without noticeable deterioration in performance. A final test-to-destruction of the coil showed that the limiting weak point in the stack was growth-sector boundaries present in the original (RE)BCO bulk.

AB - A novel concept for a compact high-field magnet coil is introduced. This is based on stacking slit annular discs cut from bulk rare-earth barium cuprate ((RE)BCO) ceramic in a Bitter-like architecture. Finite-element modelling shows that a small 20 turn stack (with a total coil volume of < 20 cm 3) is capable of generating a central bore magnetic field of > 2 T at 77 K and > 20 T at 30 K. Unlike resistive Bitter magnets, the high-temperature superconducting (HTS) Bitter stack exhibits significant non-linear field behaviour during current ramping, caused by current filling proceeding from the inner radius outwards in each HTS layer. Practical proof-of-concept for this architecture was then demonstrated through fabricating an uninsulated four-turn prototype coil stack and operating this at 77 K. A maximum central field of 0.382 T was measured at 1.2 kA, with an accompanying 6.1 W of internal heat dissipation within the coil. Strong magnetic hysteresis behaviour was observed within the prototype coil, with ≈30% of the maximum central field still remaining trapped 45 min after the current had been removed. The coil was thermally stable during a 15 min hold at 1 kA, and survived thermal cycling to room temperature without noticeable deterioration in performance. A final test-to-destruction of the coil showed that the limiting weak point in the stack was growth-sector boundaries present in the original (RE)BCO bulk.

KW - HTS Bitter-like bulk

KW - magnet

KW - (RE)BCO bulksuperconductor

KW - electromagnet

KW - Bitter-bulk

KW - Bitter magnet

UR - http://www.scopus.com/inward/record.url?scp=85184996862&partnerID=8YFLogxK

U2 - 10.1088/1361-6668/ad268b

DO - 10.1088/1361-6668/ad268b

M3 - Letter

SN - 0953-2048

VL - 37

JO - Superconductor Science and Technology

JF - Superconductor Science and Technology

IS - 3

M1 - 03LT01

ER -