Rapid Shutdown & Fast Discharge

On a serious fault, protection terminates the plasma and discharges the magnets' stored energy quickly and safely.

When a serious fault is detected — a coil quench, loss of cooling, loss of vacuum, or loss of critical power — the machine-protection system acts faster than an operator can. It terminates the plasma and, if required, discharges the magnets' stored energy into an external dump to protect the coils and structure.

Trip triggers

• Coil quench detected by independent monitoring
• Loss of cryogenic cooling to a coil
• Loss of vacuum boundary integrity
• Loss of critical power or control

Fast discharge

The high-field plug coils store large magnetic energy. On a quench, quench-detection logic opens the coil circuit into an external dump resistor, converting the stored energy to heat outside the cold mass. This limits the temperature and voltage the coil experiences, protecting it from damage. The action is automatic and independent of the normal control system.

After the trip

Following a fast discharge, the plant settles into a safe state: plasma off, coils de-energized, cooling maintained to remove residual heat, and systems monitored. Recovery follows defined procedures after the fault is diagnosed and cleared. These protection functions are designed and verified at design stage and exercised in commissioning.