Basic Mechanism of Thermal Runaway for REBCO Coils

Abstract

REBCO conductors were commercialized only recently in 2009 and therefore the magnet technology for REBCO conductors remains undeveloped. The major technological problems for REBCO coils encountered thus far are (a) degradation in the superconducting performance for mechanical reasons, (b) difficulty in protecting the magnet in the case of a super-normal transition of the REBCO coil and (c) the enormous effect of a screening-current-induced magnetic field. In this paper, the basic mechanism of premature thermal runaway in the REBCO superconductor is investigated through experiments and numerical simulations on small model coils. Effective remedies for suppressing the premature thermal runaway are discussed.