Disruption Mitigation Injection
When a breeder disruption is unavoidable, L1 fires mass or impurity injection on a deterministic trigger to radiate energy uniformly and spare the vessel.
The last controlled action before a disruption
If avoidance fails, the goal shifts to making the disruption as benign as possible. Mitigation injects material — impurity gas or pellets — that radiates the plasma's thermal energy broadly rather than letting it dump onto a small area, and that controls the runaway-electron and halo-current pathways. L1 owns the deterministic trigger for this one-shot actuation.
Why timing is absolute
Mitigation only helps if the material arrives and assimilates before the thermal quench deposits its energy. That imposes a hard deadline from trigger to material delivery. L1 fires the injector on a bounded path, and the trigger itself has a threshold-based fallback independent of any model, because a mitigation system that could miss its window would be worse than useless.
What it protects
- Spreads thermal load to avoid localized wall melting.
- Radiates energy to soften the thermal quench.
- Manages current-quench rate to limit halo and eddy forces.
- Suppresses runaway-electron seed growth where applicable.
At 9.66 MA and with the breeder's stored energy, an unmitigated disruption imposes severe electromagnetic and thermal loads. Mitigation does not prevent the disruption; it converts a potentially damaging event into a survivable one, which is why it is the terminal rung of the graded response.
One-shot determinism
Unlike a continuous loop, mitigation is a single committed action, so its determinism is about the trigger-to-delivery path being provably fast and its arming logic being correct. L1 keeps the injector armed whenever the plasma carries enough energy to warrant it, and coordinates the trigger with the current-quench and magnet protection so the machine reaches a safe state as one sequence.