A Feasibility Study on “Magnetic Dam” to Absorb Magnetic Energy in NI HTS Magnet During Quench

Abstract

When a quench occurs in a no-insulation (NI) high temperature superconductor (HTS) magnet that consists of a stack of double-pancake (DP) coils, a large amount of current is often induced in an NI DP coil that is electromagnetically coupled with neighboring DP coils. The large induced current leads to an excessive magnetic stress and occasionally damages the magnet. In this paper, we propose a new quench protection concept to reduce the amount of induced current in an NI HTS magnet. The key idea is to use resistive copper in order to absorb a portion of electromagnetic energy that is initially stored in the magnet before the quench. We tentatively name these resistive coils as a “magnetic dam,” as they may slow down the electromagnetic quench propagation speed among the NI DP coils, which may be beneficial to avoid over-stressing by the large over-current.