Speaker
Description
Magnet technologies employing REBCO high temperature superconductors (HTS) have bloomed over the last decade. Many flagship projects are pushing HTS technologies to the boundaries of achieving reliable high magnetic field. Nevertheless, quench protection of an HTS magnet remains a challenge for designers, which must be addressed to enable more practical applications of HTS magnets. That is, there is yet no definitive strategy to make a quench protection scheme for an HTS magnet, no matter the turn to turn is insulated or not. Despite the remarkable high field achieved with the no-insulation coils, its passive quench protection has not been fully quantitatively described, making it difficult to design a magnet that can rely solely on this method to survive any quench event. For insulated HTS coils, there is still no strong evidence to suggest if quench detection by resistive voltage is reliable or not. Meanwhile, other novel quench detection approaches have yet to fully demonstrate their efficiency and reliability. Another challenge regarding quench protection of an HTS magnet is what active quench protection method is available. The dump resistor is only useful for insulated coils, and one must carefully balance the magnet inductance and the operating current. Other methods to heat up the whole coil like quench heater and CLIQ could be extremely inefficient for HTS due to its high critical temperature and correspondingly high enthalpy. Beyond these technical issues, a more fundamental problem is, what could be the reason that really quenches a HTS magnet? In view of these, this talk will review the extensive experimental and numerical research conducted around these issues in the past decade to enhance our understanding of HTS quench dynamics that specially focusing on the thermal and electrical processes. The insights gained from such research would bring us one step closer to developing a mature and reliable quench protection scheme for HTS magnets.
