Speaker
Description
The development of high-field magnets using high-temperature superconductors (HTS) presents significant challenges, particularly in quench detection and protection. Due to the inherently slow quench propagation in HTS, conventional detection and protection methods may be ineffective. To address these challenges, novel approaches are being explored by the magnet community. A possible method involves winding superconducting coils in a bifilar configuration, where two adjacent conductors are wound side by side, enable operation in series mode during normal conditions and in anti-parallel mode during a quench event. In this configuration, the coil differential inductance is close to zero during a quench, allowing extremely rapid current oscillations through capacitor discharge. This process induces fast heat dissipation, effectively quenching the entire coil on the microsecond timescale. Additionally, the strong intrinsic coupling between the two halves of the bifilar coil effectively cancels electrical noise in voltage taps, enabling accurate measurement of voltage growth due to a spontaneous quench. In this paper, we demonstrate the feasibility of this concept using a REBCO bifilar racetrack coil. We describe the design and construction of the magnet and present experimental results obtained from testing in liquid nitrogen. These results confirm the ability to quench the entire coil within microseconds and detect resistive voltage growth before a spontaneous quench poses a danger. Furthermore, we validate a simulation model capable of reproducing the coil behavior under rapid current oscillations, showing good agreement with experimental results.
