Meter-scale REBCO tapes with a current flow diverter architecture

The current flow diverter (CFD) architecture allows increasing the normal zone propagation velocity (NZPV) of rare-earth barium copper oxide (REBCO) tapes. A continuous reel-to-reel CFD fabrication process has been developed to produce a high quality one meter long CFD REBCO tape. Standard scratch tests showed that the adhesion strength of the silver layer of a regular commercial tape and an annealed CFD tape are similar while being slightly lower in the case of a nonannealed CFD tape. Depending on the CFD architecture, experimental measurements revealed an increase in the NZPV of CFD tapes by a factor of 6 to 22 with respect to regular tapes, which is comparable to previous results obtained on short length CFD tapes (12 cm). A detailed analysis combining optical microscopy and numerical simulations revealed that the reel-to-reel CFD fabrication process minimizes geometrical imperfections, which results in a good NZPV uniformity over long lengths. This demonstration of the effectiveness of the CFD concept in long-length CFD tapes represents an important step toward the potential development of a safe and more reliable protection scheme in high field magnets and other high current carrying REBCO based devices.