Over-current quench test and self-protecting behavior of a 7 T/78 mm multi-width no-insulation REBCO magnet at 4.2 K. (25th September 2015)

• Record Type: Journal Article
• Authors: Song, Jung-Bin; Hahn, Seungyong; Lécrevisse, Thibault; Voccio, John; Bascuñán, Juan; Iwasa, Yukikazu
• Is Part Of: Superconductor science & technology. Volume 28:Number 11(2015:Nov.)
• Publication Date: 2015-09-25
• Subjects: multi-width -- no-insulation -- REBCO magnet -- self-protecting; Superconductivity -- Periodicals; Superconductors -- Periodicals; 537.623
• DOI: 10.1088/0953-2048/28/11/114001
• Languages: English
• ISSNs: 0953-2048

Abstract

Abstract: This paper presents the over-current quench test and post-quench operation results of a 7 T 78 mm winding diameter multi-width (MW), no-insulation (NI) magnet in a bath of liquid helium at 4.2 K. The MW-NI magnet consists of 13 double-pancake (DP) coils wound with GdBCO tapes having five different widths ranging from 4.1–8.1 mm. After the magnet reached 7.3 T at 253 A, the magnet current was further increased purposely until the magnet quenched at 312 A, corresponding to a current density of 895 A mm −2 for the central DP coils of the narrowest 4.1 mm tape. The NI DP coils showed a fast magnetically coupled quench propagation from the quenched DP to the rest of the 'healthy' DP coils. The stored magnetic energy of 25.4 kJ was completely dissipated in 0.3 s with an average dissipation power rate of 85 kW. The post-quench magnet, operated sequentially in baths of liquid nitrogen at 77 K and in liquid helium at 4.2 K, showed no discernable changes from the pre-quench magnet in their key parameters, except the magnet characteristic resistance, pre-1.4 mΩ versus post-3.6 mΩ. Thus, a forced quench of the magnet, thanks to the NI winding technique, kept the integrity—mechanical, electrical, and magnetic—of this NI magnet intact.