High-throughput manufacturing of REBCO superconductor tapes

The ultra-high critical magnetic fields of RE-Ba-Cu-O (REBCO RE=rare earth) High Temperature Superconductors (HTS) are very attractive for compact fusion energy systems that can operate over a temperature range of 4 – 50 K in magnetic fields beyond the realm of Nb3Sn wires. Because of the tremendous pull from compact fusion, REBCO tape supply is substantially trailing demand. 10,000 kilometers of tape is required for just only prototype compact fusion device whereas world-wide annual capacity is only a few thousand kilometers. A challenge with REBCO tapes is the high capital equipment cost, about $50M for a 1000 km/year production capacity. At this time, companies are duplicating pilot-scale manufacturing tools to build up capacity. A better approach needs to be developed to increase throughput by several-fold without a large increase capital investment. As an example, if the production capacity per tool could be increased 10x to 2000 km/year with only a 2-fold higher capital investment, it will address concerns with both tape availability and cost. Throughput increase could be realized by large-area deposition (over 0.5 m2) or higher deposition rate while still maintaining high quality, consistency and uniformity of performance of REBCO tapes. Another approach to address the tape availability issue is to increase the critical current. Today’s cables made for compact fusion magnets use over 200 tapes, so increasing the critical current by 5x can reduce the number of tapes by about 5-fold which will reduce cost and alleviate availability concerns. Our partner, the University of Houston (UH) has demonstrated an Advanced Metal Organic Chemical Vapor Deposition (MOCVD) technology that has yielded critical current levels at 20 K, 20 T up to 5x higher than that of commercial tapes in short samples. The A-MOCVD technology has been successfully scaled up to 50-meter lengths with critical current 3.3x that of commercial tapes at 20 K, 20 T. These processes need to be scaled up to commercially-usable lengths of 300 – 500 meters. The high critical currents have to be demonstrated uniformly and consistently over the long lengths. In the proposed project, AMPeers and UH will develop technologies to increase the throughput of Advanced MOCVD process to increase the production capacity per tool. An advantage of MOCVD over competing processes is large area deposition. Innovative designs of A-MOCVD tool and process will be employed to achieve high throughput while maintaining the excellent critical current at 20 K, 20 T. In-line quality control methods will be utilized to assure consistent and uniform in-field critical current over long lengths of REBCO tapes made by high throughput A-MOCVD. In Phase II, we will implement the best approach for high throughput to demonstrate long tapes (> 100 meters) while maintaining the 4x critical current of today’s commercial REBCO tapes at 20 K, 20 T.