The paper describes intricate cross coupling of quench detection and energy extraction systems to protect a hybrid dipole magnet built with Low Temperature Superconductor (LTS) outer coils and High Temperature (HTS) inner coils during the quench. Quench characteristics of HTS and LTS are quite different and various different parameters had to be considered in designing reliable quench protection system.
LTS-HTS hybrid dipole consist of 10T (Nb3Sn) outer coil and 12mm ReBCO tape HTS insert to form hybrid dipole with very tight magnetic coupling. LTS and HTS coils are powered by independent current source power supplies along with independent ultra fast energy extraction system but common quench detector hardware platform using Real Time National Instrument PXIe Data Acquisition System, programed in LabView. The novel quench detection algorithm and timing sequence were developed. Fast energy extraction system was realized by using high power IGBT switches.
The behavior of inductive cross coupling of collapsing magnetic fields during energy extraction at quench are clearly presented. Tests were performed at Vertical Cryogenic Test Facility of Superconducting Magnet Division of Brookhaven National Laboratory in 4.2K liquid helium bath.