Quench Protection Reflex Chain

A superconducting magnet losing superconductivity must be detected and de-energized in milliseconds; the quench chain is the fastest shared reflex on both machines.

From detection to a de-energized magnet

Both machines run high-field superconducting magnets — the breeder at up to 16.84 T peak field, the burner at 26.49 T plug and 17 T throat. If any conductor loses superconductivity (a quench), the local resistive heating can damage the magnet unless the stored magnetic energy is extracted fast. The quench protection chain detects the normal zone, confirms it, and drives the energy into external dump resistors within the magnet's safe hot-spot time.

def quench_chain(normal_zone_voltage, threshold_V, confirm_windows, dump):
    if normal_zone_voltage <= threshold_V:
        return 'permit'
    # brief confirmation to reject noise, then irreversible dump
    if confirm_windows >= 2:
        dump.fire()
        return 'DUMP fired -> energy to resistors'
    return 'arming'

def hotspot_ok(detect_ms, dump_time_ms, allowable_ms):
    return (detect_ms + dump_time_ms) <= allowable_ms

The budget that must be met

The whole chain — detect, briefly confirm, fire the dump, extract the current — must complete inside the conductor's allowable hot-spot time, or the local temperature exceeds safe limits. Detection therefore favors fast, robust indicators; confirmation is just long enough to reject noise; and the dump path is pre-armed so firing is immediate.

• Detect: normal-zone voltage and complementary indicators, voted for robustness.
• Confirm: a short window to reject transients, never long enough to blow the hot-spot budget.
• Dump: irreversible energy extraction into external resistors, fail-safe on loss of hold.

The chain is the fastest shared reflex on both machines, so it sets a floor on the whole reflex-tier timing design: whatever budget the hot-spot time allows becomes the target the detection, confirmation, and dump stages must fit inside with margin. Every microsecond spent confirming a quench to reject noise is a microsecond taken from the dump, so the confirmation window is tuned to the minimum that rejects known transients and no longer, and the dump path is pre-armed so firing adds no mechanical delay.

Detection timing specifics are in REBCO quench detection timing, and the extraction hardware in magnet energy extraction. The chain shares its budget-and-margin methodology with disruption mitigation latency; both race a physical clock.