MAGNETIC SHIELDING BEHAVIOR OF YBCO CYLINDERS - A UNIVERSAL SCALING PROPERTY

Magnetic shielding studies have been carried out to investigate the us efulness of high-T-c YBCO ceramics for EMS applications. The starting materials were single-phase YBCO powder. The cylinders were prepared b y uniaxial compresssion and isostatic compression, with and without Ag additive. The shielding field H, defined as the value of the applied field at which a detectable field will be seen inside the superconduc ting shield, was 12 G for the shield prepared by uniaxial compression and around 17 G for shields prepared by isostatic compression. Measure ments were done in both ac and de fields. The field inside the shield for the sinusoidal ac applied field is highly distorted, showing the p resence of three higher harmonics. The penetrated waveform was Fourier -analyzed to yield the rms value of B-in. When the normalized value of B was plotted against the normalized value of H with respect to H, a ll the points corresponding to different shields fall on the same curv e.