Low frequency ac shielding effectiveness of a bulk normal metal / high Tc superconducting composite
✍ Scribed by J.J. Calabrese; J.C. Garland
- Book ID
- 104356659
- Publisher
- Elsevier Science
- Year
- 1990
- Tongue
- English
- Weight
- 225 KB
- Volume
- 165-166
- Category
- Article
- ISSN
- 0921-4526
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✦ Synopsis
We have investigated the electromagnetic shielding effectiveness of a random bulk Ag/YBa,Cu,O,., composite material containing 40% Ag. A cylindrical enclosure was fabricated out of the composite material, and the shielding effectiveness of the material was determined by measuring the frequency dependence of the r.f. coupling between two coils separated by the enclosure walls. At room temperature, the enclosure was essentially transparent to r.f. at frequencies below lkHz, while at higher frequencies, eddy currents in the connected Ag matrix of the composite attenuated the coupled r.f. in accord with the classical flR skin depth expression.
At 77K, however, the superconducting phase introduced a minimum of 70 dB additional attenuation below lkHz, with a smooth crossover into the high-frequency skin depth regime.