Stability of cable-in-conduit internally-cooled superconductor subject to local disturbance-stabilityanalysis based on measured transient heat transfer of SHE in narrow channel

Abstract

It is likely that a quench in the cable-in-conduit internally cooled superconductor (CCICS) is initiated by a quench of a single strand due to strand motion. The disturbance due to the strand motion is highly localized and has short duration time of less than 1 ms. We have been studying the stability of CCICS assuming that the disturbance energy is abruptly put into a small part of a single strand. To perform this analysis, the heat transfer characteristics of supercritical helium(SHE) confined to narrow channels formed by strands were measured. The paper presents the experimental heat transfer data which well agree with calculated values based on a conduction model in short time range while a normal zone caused by a disturbance disappears or grows to propagate. The transient heat transfer in narrow channels is affected by energy input to SHE in the channels. According to our stability analysis of a model conductor, energy released during initiation of a quench is not large enough to induce SHE flow affecting the heat transfer.