The fabrication and characterization of high temperature superconducting magnetic shields

Tubes fabricated of polycrystalline YBa/sub 2/Cu/sub 3/O/sub 7-x/ are characterized, and details of the fabrication procedure are discussed. The microstructure of the tubes determined by scanning electron microscopy and X-ray diffractometry is described. Resistive measurements of T/sub c/ and Delta T/sub c/ have been made. The tubes have also been characterized by means of SQUID (superconducting quantum interference device) magnetometry. The temperature dependence of magnetic fields trapped axially in the tubes has been measured and estimates of penetration depth are given. Moreover, measurements of the transverse shielding effectiveness of the tubes have been made and are compared with theoretical predictions. Studies on flux penetration into the tubes are described. Findings from the microstructure studies are correlated with the observed superconductivity properties. The results on the high-temperature materials are compared to results obtained previously on tubes made from conventional superconductors.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>