Superconductivity News Forum (SNF)
Presentation, PDFQuench Protection of Very Large, 50 GJ Class and High-temperature Superconductor Based Detector Magnets
Matthias Mentink, Alexey Dudarev, Tim Mulder, Jeroen Van Nugteren, and Herman ten Kate
CERN, 1217 Meyrin, Switzerland
E-mail: [email protected]
Abstract — An investigation is performed on the quench behavior of a conceptual 50 GJ 8 T high-temperature-superconductor-based solenoid. In this design, a 50 kA Conductor-On-Round-Core Cable-In-Conduit conductor utilizing ReBCO technology is envisioned, operating at 40 K. Various properties such as resistivity, thermal conductivity, and heat capacity are very different at this temperature, which affects the quench behavior.
It is found that the envisioned conductor is very stable with an MQE of about 2 kJ. However the quench propagation velocity is typically about 20 mm/s so that creating a wide-spread normal zone throughout the coil is very challenging. Moreover an extraction voltage exceeding 20 kV would be required to ensure a hot-spot temperature below 100 K once a thermal runaway occurs.
A novel concept dubbed ’Rapid Quench Transformation’ (RQT) is proposed whereby the superconducting conductor is co-wound with a normal conductor to achieve a high degree of inductive coupling. This geometry allows for a significant electric noise reduction, thus enabling low-threshold quench detection. The secondary circuit is connected in series with a stack of diodes, not allowing current transfer during regular operation, but very fast current transfer once a quench is detected. With this approach, the hot-spot temperature can be kept within 20 K of the cold mass temperature at all times, the hot-spot temperature is well below 100 K and just under 80% of the stored energy can be extracted during a quench.
It is found that the envisioned conductor is very stable with an MQE of about 2 kJ. However the quench propagation velocity is typically about 20 mm/s so that creating a wide-spread normal zone throughout the coil is very challenging. Moreover an extraction voltage exceeding 20 kV would be required to ensure a hot-spot temperature below 100 K once a thermal runaway occurs.
A novel concept dubbed ’Rapid Quench Transformation’ (RQT) is proposed whereby the superconducting conductor is co-wound with a normal conductor to achieve a high degree of inductive coupling. This geometry allows for a significant electric noise reduction, thus enabling low-threshold quench detection. The secondary circuit is connected in series with a stack of diodes, not allowing current transfer during regular operation, but very fast current transfer once a quench is detected. With this approach, the hot-spot temperature can be kept within 20 K of the cold mass temperature at all times, the hot-spot temperature is well below 100 K and just under 80% of the stored energy can be extracted during a quench.
Keywords (Index Terms) — Detector magnet, CORC, cable-in-conduit conductor, quench protection.
IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2016.
Submitted November 16, 2015; Selected November 17, 2015. Reference No. ST/STP503; Category 6.
This invited presentation 3OrAC_02 was given at MT-24. A manuscript was submitted to IEEE Trans. Appl. Supercond. for possible publication.
Submitted November 16, 2015; Selected November 17, 2015. Reference No. ST/STP503; Category 6.
This invited presentation 3OrAC_02 was given at MT-24. A manuscript was submitted to IEEE Trans. Appl. Supercond. for possible publication.