Magnet Quench Protection
If part of a REBCO coil goes normal, its stored energy must be extracted before local heating damages the conductor.
What a quench is
A quench is the transition of part of a superconducting magnet to the normal, resistive state. The magnet stores large energy at full field; if that energy deposits in a small normal zone, local temperature and voltage spike and the conductor can be destroyed. Quench protection detects the event and safely dumps the stored energy.
Why REBCO makes this hard
REBCO's strength — high temperature margin — is also its protection weakness. Normal zones propagate slowly in HTS, so a hotspot can grow locally before detection sees a global voltage. Detection must therefore be fast and sensitive, and the design leans on generous copper stabilizer to slow the temperature rise and buy detection time.
- Slow normal-zone propagation is the central HTS challenge.
- Copper stabilizer sets the adiabatic temperature-rise limit.
- Detection thresholds trade false trips against protection margin.
- Dump resistor and switchgear size the extraction rate.
Status
Quench protection is a design item folded into the magnet gate. It is well understood in principle for low-temperature magnets; the HTS-specific detection and stabilizer margins are what the breeder's magnet program must demonstrate. Protection choices feed back into conductor cross-section, which feeds back into center-stack volume.
Segmentation and detection redundancy
Dividing the winding into electrically segmented sections limits how much stored energy any single hotspot can absorb, and layering independent detection methods reduces the chance a slow HTS normal zone escapes notice. Both add complexity and instrumentation, but they buy the detection time that REBCO's slow propagation would otherwise deny the protection system.
This page documents a design and simulation study, not a built machine. Construction begins Q2 2027; first-of-a-kind first tritium is targeted near 2030. Figures are computed, reproducible targets, not measurements.