Speaker
Description
Nearly four decades have passed since the first discovery of high temperature superconductor (HTS). To date multiple HTS wires have been developed and some of them are now readily available in a commercial market. REBCO has been regarded as one of the most advanced HTS wire options with the benefit of large in-field current carrying capacity and strong substrate mechanical toughness. The recent high expectation of REBCO for “compact fusion” accelerates global competition of mass production of REBCO wire, which naturally leads to the wire cost reduction for the first time in the history of HTS. Nowadays, over hundreds of REBCO coils are being built annually ranging laboratory use to various industrial applications. Yet, we are still facing fundamental challenges to ensure our REBCO technology for our industrial partners. For example, precise estimation of critical current of an REBCO magnet is still challenging. And REBCO magnets are designed without clear understanding of temporal and spatial distribution of currents—transport, screening, and radial leak (in case of no-insulation)—even in steady-state not to mention under quench. Magnet designers are still struggling with in-consistent Ic(B,T) behaviors and weak delamination force of REBCO wire. As a result, high field REBCO magnets are designed and constructed without precise estimation of their electrical and mechanical limits. To date, REBCO magnets that reach over 30 T twice or more are rare; none are under routine service. This paper summarizes lessons learned from the recent milestone REBCO magnets and categorized key technical challenges in both conductor and magnet perspectives. Then, suggestions on collaborative R&D directions to our REBCO community toward enhancing industrial level of technology readiness for REBCO magnet technology are followed.
