TY - JOUR
T1 - Mitigating ab-Plane Critical Current Density Inhomogeneity in Bulk HTS Rings for the Generation of NMR-Grade Magnetic Fields
AU - Beck, Michael R.
AU - Ainslie, Mark D.
N1 - Publisher Copyright:
© 2002-2011 IEEE.
PY - 2022/3/1
Y1 - 2022/3/1
N2 - (RE)-Ba-Cu-O ring bulks, used as trapped field magnets, show great promise as a compact and lightweight source for generating the magnetic fields required for nuclear magnetic resonance (NMR). The inhomogeneities introduced by the growth process of such bulks pose a challenge to the required field uniformity for NMR. In this study, we model a stack of ring bulks with varying ab-plane inhomogeneity and orientation to investigate the impact on the trapped field profile following field cooled magnetization. For a pair of rings, by offsetting the growth sector boundaries (GSBs), the inhomogeneity of the circumferential field at the mid-plane can be reduced by up to 65% compared with aligned GSBs, for less than 0.4% reduction in the central trapped field strength. Using two pairs of rings allows for the generation of a larger homogeneous region at the center of the bore, with a lower peak-peak variation across the measuring volume. The relative harmonic weighting of the field moves to higher orders, requiring more complex shimming coils to correct the residual field.
AB - (RE)-Ba-Cu-O ring bulks, used as trapped field magnets, show great promise as a compact and lightweight source for generating the magnetic fields required for nuclear magnetic resonance (NMR). The inhomogeneities introduced by the growth process of such bulks pose a challenge to the required field uniformity for NMR. In this study, we model a stack of ring bulks with varying ab-plane inhomogeneity and orientation to investigate the impact on the trapped field profile following field cooled magnetization. For a pair of rings, by offsetting the growth sector boundaries (GSBs), the inhomogeneity of the circumferential field at the mid-plane can be reduced by up to 65% compared with aligned GSBs, for less than 0.4% reduction in the central trapped field strength. Using two pairs of rings allows for the generation of a larger homogeneous region at the center of the bore, with a lower peak-peak variation across the measuring volume. The relative harmonic weighting of the field moves to higher orders, requiring more complex shimming coils to correct the residual field.
KW - Bulk superconducting rings
KW - field homogeneity
KW - growth sector boundary
KW - high-temperature superconductors
KW - HTS modelling
KW - nuclear magnetic resonance
KW - numerical modelling
UR - http://www.scopus.com/inward/record.url?scp=85125721765&partnerID=8YFLogxK
U2 - 10.1109/TASC.2022.3155539
DO - 10.1109/TASC.2022.3155539
M3 - Article
AN - SCOPUS:85125721765
SN - 1051-8223
VL - 32
JO - IEEE Transactions on Applied Superconductivity
JF - IEEE Transactions on Applied Superconductivity
IS - 6
M1 - 6800705
ER -