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 ľ 50 K in magnetic fields beyond the realm of Nb3Sn wires. REBCO tapes are now manufactured in significant volume by six companies, four of which are supplying tapes to compact fusion companies. Because of the tremendous pull from compact fusion, REBCO tape supply is substantially trailing demand. 10,000 kilometers of tape is required for just a 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. For instance, one company added five REBCO deposition tools, each with 200 km/year capability, to reach 1000 km/year annual production capability. 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 could be increased by large-area deposition and higher deposition rate while maintaining high quality, and uniformity of REBCO tapes. Another approach to address the tape availability issue is to increase the critical current. Todayĺs cables made for compact fusion magnets use 200+ tapes, so increasing the critical current by 4x can reduce the number of tapes by about 4-fold which will reduce cost and alleviate availability concerns. Our partner, the University of Houston has demonstrated an Advanced Metal Organic Chemical Vapor Deposition (MOCVD) technology that has yielded critical current levels at 20 K, 20 T up to 4x 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 3.5x that of commercial tapes at 20 K, 20 T. In this project, AMPeers and the University of Houston are developing technologies to increase the throughput of the Advanced MOCVD process to increase the production capacity per tool. An advantage of MOCVD over competing processes is large area deposition. In the Phase I project, innovative designs of A- MOCVD tool and process are being developed to achieve high throughput while maintaining the excellent critical current at 20 K, 20 T. In-line quality control methods are being utilized to assure consistent and uniform in-field critical current over long lengths of REBCO tapes made by high throughput A-MOCVD. In the Phase II project, we will implement the best approach for high throughput to demonstrate long tapes (> 100 meters) while maintaining the 3-4x critical current of todayĺs commercial REBCO tapes at 20 K, 20 T.