Magnetic shielding characteristics of second generation high temperature superconductors at variable temperatures obtained by cryogenic helium gas circulation

Magnetic shielding characteristics of 40 mm wide second generation high temperature superconducting (2GHTS) materials were studied at variable temperatures. Shielding characteristics were measured in DC and variable frequency AC magnetic fields at a range of magnitudes up to 60 mT. Magnetic shields fabricated in the form of short cylinders were studied with magnetic field perpendicular to their axis. Shielding properties of single and double layer shields were compared at various temperatures between 50 and 80 K. Shielding factor up to 98% was achieved. The benefit of lower temperatures is particularly visible at higher magnetic fields. Trends of shielding characteristics modeled as a function of external magnetic field strength with finite element models using COMSOL match with those of the experimental observations.