Hysteresis loss in a multifilament Superconductor
Calorimetric measurements of the alternating field eddy current losses in three twisted filamentary, mixed-matrix superconductors were recently reported and compared with calculated losses based on the continuum model for a multifilament conductor. The measurements and comparison are extended here to the hysteresis loss. A typical cross section of the three conductors, which differ only in twist pitch, is shown in Fig. 1. The conductors, which were developed at the Los Alamos Scientific Laboratory, have a nominal composition of 3CuNi: 3Cu: INbTi and consist of 397 originally hexagonal copper-clad filaments of Nb-48wt. %Ti embedded in a Cu- 30% Ni matrix. The filaments are approximately hexagonal, being 9 μm across hexagonal fiats. The overall conductor radius is 0.026 cm and the filaments occupy a radius of about 0.024 cm. The twist pitch lengths for the three samples are 0.63,0.43, and 0.32 cm.
KeywordsCritical Current Density Bias Field Hysteresis Loss Eddy Current Loss Filament Axis
electric field parallel to filament axis
magnetic field vector
applied magnetic field
local magnetic field at a filament
amplitude of ac magnetic field Hp = magnetic field for full penetration of filament
critical current density
length of one complete twist
magnetization transverse to the filament axis
hysteresis loss per unit volume of conductor
radius of the part containing filaments
radius of conductor
volume fraction of superconductor
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