Development of Bi-2223 Superconducting Wires for AC Applications

Abstract

Advanced silver sheathed Bi-2223 superconducting tapes have been developed for AC-applications such as electric power cables and transformers, which require reduced AC-losses. Twisted multi-filament and inter-filament resistive barriers were applied to eliminate the electromagnetic inter-filament coupling, which is the primary mechanism in enhancing AC-losses. A multi-filamentary wire with a honeycomb type thin ceramic barrier was designed and manufactured in an attempt to realize low AC-losses without degrading the transport properties of the conductor. AC-losses of the manufactured wire were reduced drastically when compared to those of conventional wires without barriers. Using the measured properties of the manufactured wire as a basis, a design study along with projected AC-losses for a superconducting power cable is presented.

AC Loss Reduction in Bi2223 Tapes with Interfilamentary Oxide Barriers

“…The introduction of highly resistive layers as barriers around each filament is considered to be effective methods to increase the transverse resistivity [4][5][6][7][8][9][10]. The oxide material usable as the barriers should be highly-resistive, nonpoisonous to Bi2223 phase during heat treatment, and also should be easily deformed during cold working.…”

Interfilamentary coupling properties of Bi2223/Ag tapes with oxide barriers subjected to AC perpendicular magnetic field

“…SrZrO 3 powders with the mean grain size below 1 lm were selected as barrier materials. Based on the previous study for Ca 2-CuO 3 barrier tapes [9][10][11], additional Bi2212 powder corresponding to 20 wt.% was mixed with SrZrO 3 to improve its ductility for cold working. The precursor powders were packed into pure Ag tube with an outer diameter of 9.4 mm and a wall thickness of 0.7 mm.…”

“…Most popular method for introducing barriers is the coating of oxide powder on the surface of monocore wire [5][6][7][8][9][10][11][12][13][14][15][16]. The oxide material usable as barriers should be highly-resistive, non-poisonous to Bi2223 phase formation during heat treatment, and also should be deformable during cold working such as drawing and flat rolling.…”

“…BaZrO 3 is known to be effective to increase the matrix resistivity and also to decouple the filaments, but they cause significant degradation of critical current density (J c ) due to their poor ductility [5,7,9]. The tapes with SrCO 3 barriers show reasonably good transport properties [10,11], but it has been pointed out that SrCO 3 barriers is not sufficient to increase transverse resistivity and to suppress the filament coupling [10]. In our preliminary studies [12][13][14][15] [15], resulting the insufficient enhancement of transverse resistivity.…”

Perspectives of elementary technologies for AC power applications of high temperature superconductors

“…The resistivity of the Ag or Ag alloy matrix is very low and, furthermore, superconducting bridges between the filaments are formed during the heat treatment. To prevent the formation of those bridges and increase the transverse resistivity, techniques to insert highly resistive thin barriers among the filaments are being developed [13,14]. At the present, it is predicted that it will take some years to develop the techniques.…”