AC susceptibility of a monofilament Bi-2223/Ag superconducting tape in a perpendicular field

Measurements and calculations are presented of the real (chi') and imaginar y (chi") parts of the AC susceptibility of a monofilament silver-sheathed B i-2223 tape as a function of temperature T = 4-130 K, frequency omega/2 pi = 5 Hz-5 kHz and ac magnetic field amplitude mu(0)H(m) = 0.02-7 mT. The sus ceptibilities consist of a hysteretic component due to induced currents in the superconductor core and an eddy current component due to induced eddy c urrents in the silver sheath. At high temperatures (> 70 K) the low frequen cy limit is used to rigorously calculate the hysteretic and eddy current su sceptibilities while at low temperatures the susceptibility is approximatel y described as being due to eddy currents flowing along the edges of the ta pe. The measured chi" and hence AC loss at low frequencies (< 50 Hz) and hi gh temperatures is dominated by the hysteretic loss which varies with ampli tude but is essentially independent of frequency. At higher frequencies and low temperatures, the eddy current loss of the silver sheath becomes domin ant and increases with increasing frequency. (C) 1999 Elsevier Science B.V. All rights reserved.