AC loss properties of MgB₂multifilament wires

Abstract

We designed and fabricated two types of composite wires with 6 MgB2 filaments. One is a Cu-sheathed Nb-barrier wire and the other is a CuNi-sheathed Ta-barrier wire. The transverse-field losses of the trial wires were measured with a standardized pickup coil system in liquid helium. We evaluated the observed AC losses using two structural models, a multifilament conductor model and a hollow-cylindrical one. For the CuNi-sheathed Ta-barrier wire, the AC loss property can be explained by the usual model of multifilament conductors. Further reductions in AC loss can be expected by making the filaments thinner. For the Cu-sheathed Nb-barrier wire, theoretical considerations suggest the multifilament structure behaves as a hollow-cylindrical superconductor in the AC loss property. Thus, we need to pay particular attention to designing the barrier material for reduction in the AC loss.

AC Loss Measurements on Multi-Filamentary $ \hbox{MgB}_{2}$ Wires With Non-Magnetic Sheath Materials

“…with simultaneously applied magnetic fields and transport currents at variable temperatures, are necessary. In the literature AC loss measurement results due to either AC transport currents [13], [14] or AC applied magnetic fields [14]- [16] have been reported.…”

Designing and Commissioning an Experimental Setup to Evaluate AC Losses in Superconductors Under Transverse Rotating Fields

“…E XPERIMENTAL measurement of AC losses in superconducting wires can present significant challenges due to their relatively small magnitude, typically on the order of milliwatts. Despite these difficulties, several successful studies have reported the measurement of AC losses in wires and cables operating under stationary alternating field conditions [1]- [3]. These can be measured through the electromagnetic measurements [4], [5], the electric-heater-based calorimetric method [6], or the cryogen boil-off-rate based calorimetric method [7].…”

AC losses and transverse resistivity in filamentary MgB2 tape with Ti barriers

“…Also diffusion barriers between MgB 2 filaments and the copper stabilization may affect the transverse resistivity substantially. The most frequently used barrier material is Nb [4,[7][8][9]. Fe buffer layer was used in Ni sheathed filamentary MgB 2 tapes with 14 filaments [10].…”