Magnetic Shielding of Open and Semi-closed Bulk Superconductor Tubes: The Role of a Cap

In this paper we investigate the magnetic shielding of hollow and semi-closed bulk superconducting tubes at 77 K. We first consider the properties of a commercial Bi-2223 tube closed by a disk-shaped cap placed against its extremity. The results are compared with those obtained on a bulk large grain Y-Ba-Cu-O (YBCO) tube produced by buffer-aided top seeded melt growth. In this process, the disk-shaped pellet and the tubular sample are grown together, resulting in a tube naturally closed at one extremity. The field to be shielded is either parallel or perpendicular to the main axis of the tube. The experimental results are compared with the results of finite element numerical modeling carried out either in two dimensions (for the axial configuration) or three dimensions (for the transverse configuration). In the axial configuration, the results show that the shielded volume can be enhanced easily by increasing the thickness of the cap. In the transverse configuration, the results show the critical role played by the superconducting current loops flowing between the tube and the cap for magnetic shielding. If the tube and the cap are separated by a non-superconducting joint or air gap, the presence of a cap leads only to a small improvement of the transverse shielding factor, even for a configuration where the gap between the cap and the tube contains a 90° bend. The cap leads to a significant increase in the transverse shielding when the cap and the tube are naturally grown in the same process, i.e., made of a continuous superconducting material. The experimental results can be reproduced qualitatively by 3-D numerical modeling.

[1]  C. Petrone,et al.  Relaxation Phenomena in a Long MgB2 Tube Subjected to Transverse Magnetic Field, at 4.2 K , 2018, IEEE Transactions on Applied Superconductivity.

[2]  C. P. Bean.  Magnetization of hard superconductors , 1962 .

[3]  D. Barna.  High field septum magnet using a superconducting shield for the Future Circular Collider , 2017 .

[4]  S. Nishijima,et al.  Evaluation of solders for superconducting magnetic shield , 1991 .

[5]  M. Ainslie,et al.  Modelling of bulk superconductor magnetization , 2015 .

[6]  H. Krooshoop,et al.  Design and validation of a large-format transition edge sensor array magnetic shielding system for space application. , 2016, The Review of scientific instruments.

[7]  Wei Zhai,et al.  Buffer Pellets for High-Yield, Top-Seeded Melt Growth of Large Grain Y–Ba–Cu–O Superconductors , 2015 .

[8]  Ernst Helmut Brandt,et al.  SUPERCONDUCTOR DISKS AND CYLINDERS IN AN AXIAL MAGNETIC FIELD. I. FLUX PENETRATION AND MAGNETIZATION CURVES , 1998 .

[9]  X. Granados,et al.  Growth mechanism of Ag-foil-based artificially superconducting joints of YBa_2Cu_3O_7 monoliths , 2006 .

[10]  M. Truccato,et al.  Comparison of the Shielding Properties of Superconducting and Superconducting/Ferromagnetic Bi- and Multi-layer Systems , 2017 .

[11]  P. Tixador,et al.  Finite-element method modeling of superconductors: from 2-D to 3-D , 2005, IEEE Transactions on Applied Superconductivity.

[12]  M. Ausloos,et al.  Field penetration into hard type-II superconducting tubes: effects of a cap, a non-superconducting joint, and non-uniform superconducting properties , 2007 .

[13]  P. Vanderbemden,et al.  Bulk superconducting tube subjected to the stray magnetic field of a solenoid , 2018 .

[14]  G. Giunchi,et al.  Magnetic shielding capability of MgB2 cylinders , 2010 .

[15]  P. Vanderbemden,et al.  Shielding efficiency and E(J) characteristics measured on large melt cast Bi-2212 hollow cylinders in axial magnetic fields , 2010, 1007.4628.

[16]  P. Vanderbemden,et al.  High field behavior of artificially engineered boundaries in melt-processed YBa2Cu3O7−δ , 1998 .

[17]  P. Vanderbemden,et al.  Magnetic Shielding Above 1 T at 20 K With Bulk, Large Grain YBCO Tubes Made by Buffer-Aided Top Seeded Melt Growth , 2017, IEEE Transactions on Applied Superconductivity.

[18]  V. Selvamanickam,et al.  Joining of high current bulk Y-Ba-Cu-O superconductors , 1992 .

[19]  M. Truccato,et al.  Superconducting and hybrid systems for magnetic field shielding , 2016 .

[20]  Tianyu Pang,et al.  Experimental realization of open magnetic shielding , 2017 .

[21]  M. Ausloos,et al.  Magnetic shielding properties of high- Tc superconducting hollow cylinders: model combining experimental data for axial and transverse magnetic field configurations , 2009 .

[22]  M. Chorowski,et al.  Combined magnetic screen made of Bi-2223 bulk cylinder and YBCO tape rings—Modeling and experiments , 2015 .

[23]  S. Nariki,et al.  Performance and applications of quench melt-growth bulk magnets , 2016 .

[24]  P. Lenisa,et al.  A bulk superconducting MgB$_2$ cylinder for holding transversely polarized targets , 2018, Proceedings of 23rd International Spin Physics Symposium — PoS(SPIN2018).

[25]  Christophe Geuzaine,et al.  Numerical simulation of the magnetization of high-temperature superconductors: a 3D finite element method using a single time-step iteration , 2008, 0811.2883.

[26]  P T Yang,et al.  Fabrication and properties of single domain GdBCO superconducting rings by a buffer aided Gd+011 TSIG method , 2017 .

[27]  Enric Pardo,et al.  3D magnetization currents, magnetization loop, and saturation field in superconducting rectangular prisms , 2017, 1703.05529.

[29]  B. D. Cabrera.  The use of superconducting shields for generating ultra-low magnetic field regions and several related experiments , 1975 .

[30]  P. Vanderbemden,et al.  Magnetic Shielding With YBCO Coated Conductors: Influence of the Geometry on Its Performances , 2013, IEEE Transactions on Applied Superconductivity.

[31]  D. Givord.  Introduction to Magnetism and Magnetic Materials , 2001 .

[32]  Fedor Gömöry,et al.  A quasistatic magnetic cloak , 2013 .

[33]  K. Dehmelt,et al.  A magnetic field cloak for charged particle beams , 2017, 1707.02361.

[34]  Yunhua Shi,et al.  Multiple seeding for the growth of bulk GdBCO–Ag superconductors with single grain behaviour , 2016 .

[35]  A. Mager,et al.  Magnetic shields , 1969 .

[36]  M. Zhang,et al.  Magnetic Shielding Characteristics of Second Generation High Temperature Superconductors at Variable Temperatures Obtained by Cryogenic Helium Gas Circulation , 2015, IEEE Transactions on Applied Superconductivity.

[37]  P. Arpaia,et al.  MgB2 cylindrical superconducting shielding for cryogenic measurement applications: a case study on DC current transformers , 2014 .

[38]  M. Chorowski,et al.  Frequency Effect on Shielding Quality of Closed Superconducting Magnetic Shields Made of Superconducting Tapes , 2016, IEEE transactions on applied superconductivity.

[39]  Yunhua Shi,et al.  Control of Y-211 content in bulk YBCO superconductors fabricated by a buffer-aided, top seeded infiltration and growth melt process , 2016 .