Title :
ROEBEL Assembled Coated Conductors (RACC): Preparation, Properties and Progress
Author :
Goldacker, W. ; Frank, A. ; Heller, R. ; Schlachter, S.I. ; Ringsdorf, B. ; Weiss, K.P. ; Schmidt, C. ; Schuller, S.
Author_Institution :
Forschungszentrum Karlsruhe ITP, Karlsruhe
fDate :
6/1/2007 12:00:00 AM
Abstract :
RBCO (R = Y or rare earth element) coated conductors (CC) are the most promising HTS materials for future high field coils operated at moderately high temperature (40-50 K). Coils are planned for the second generation of fusion reactors (DEMO, "DEMOnstrator") and beyond. A ROEBEL bar concept for a high current (kA-class) low AC loss cable is the most suitable assembling technique for conductors in magnet windings due to the flat rectangular cross section. The presented RACC-cable technique (RACC=ROEBEL assembled coated conductors) works with pre-shaping of tapes into strands with the ROEBEL specific meander geometry. The usually very good bending properties of the CC support the assembling procedure of the RACC-cable. We report on a 16 strand RACC-cable with 19 cm transposition length made from CC material from the commercial supplier SuperPower which reached 1020 A transport critical current at 77 K (Jeng = 11.3 kAcm-2). The basic properties of the virgin YBCO tapes and the shaped strands like orientation and field dependent transport currents, current homogeneity and bending effects, were investigated and correlated with the measured properties of the RACC-cable. Calculation of the self field effects by means of a model adapted to the specific RACC-cable geometry and in particular taking into account the current distribution in the cable, explained the 30% current reduction in the cable quantitatively.
Keywords :
barium compounds; bending; composite superconductors; critical currents; fusion reactor materials; high-temperature superconductors; superconducting tapes; yttrium compounds; RACC-cable technique; ROEBEL assembled coated conductors; YBa2Cu3O7-delta; assembling technique; bending; critical current; high current low AC loss cable; magnet windings; second generation fusion reactors; size 19 cm; temperature 40 K to 50 K; virgin YBCO tapes; Assembly; Coils; Conducting materials; Conductors; Fusion power generation; Fusion reactors; Geometry; High temperature superconductors; Magnetic materials; Power cables; HTS coated conductors; ROEBEL bar; self field effects;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
DOI :
10.1109/TASC.2007.899417