Basics of Protection Technology for REBCO Coils ―with a Comparison to Low-Temperature Superconducting Coils―

Abstract

The REBa₂Cu₃O_7-δ (REBCO) coated conductor has the best superconducting properties (high critical current at high temperatures and high magnetic fields) and high mechanical strength (tensile stress). Recently, a 1.2GHz (28.2T) NMR system has become commercially available. On the other hand, however, design and manufacturing technologies for REBCO coil systems that combine robustness, safety, reliability, economy, and convenience as industrial products while maximizing the excellent properties of REBCO coated conductor have not yet been established. Therefore, in this paper, with the aim of establishing stabilization and protection technologies suitable for REBCO coil systems, with comparisons to low-temperature superconducting coils, the author discusses the occurrence of normal state transition, especially degradation and defects, and normal zone propagation characteristics, quench detection and coil protection methods. The author will also attempt to summarize the current status of the methods for monitoring the health of coils.