Breeder Sensor-to-Actuator Map

For Hyperion, each control objective is a chain from a diagnostic set to a physical actuator, with the twin and MPC in between.

The breeder control chains

The breeder (Hyperion) runs a D–T spherical tokamak with design-point plasma current 9.66 MA, fusion power 85.0 MW, Q_sci 3.076, peak field 16.84 T (8 T on-axis), and negative triangularity δ = −0.30. Every one of those quantities is held by a sensor→actuator chain.

Principal chains

• Equilibrium / position: flux loops + magnetics -> equilibrium reconstruction -> PF/CS coil supplies.
• Vertical stability: fast magnetics -> vertical-stability controller -> radial-field coil (kHz).
• Shape / triangularity: magnetics + boundary reconstruction -> shape MPC -> PF shaping coils.
• Density: interferometer chords -> density controller -> ice-piston / pellet injector + gas puff.
• Disruption avoidance: precursor features -> avoidance actuation -> beams, fueling, or mitigation injection.

A worked chain

# density control chain (breeder)
n_e   = interferometer_lineavg()        # sense (L2 timestamped)
n_ref = campaign_setpoint()             # from L4
u     = density_mpc(n_e, n_ref, twin)   # L3, 50-100 ms shadow
# actuate: L1 splits demand across fast and slow fuelers
gas_puff_valve(u.fast)                  # ms response
pellet_injector(u.slow)                 # deeper deposition

The map is deliberately many-to-many: density is served by three actuators, and one actuator (the PF coils) serves both position and shape. Allocation is resolved by MPC actuator weighting so that reserve is kept on any actuator near a limit.

Because Hyperion is a design-and-simulation study today, each chain is exercised against the digital twin; hardware-in-the-loop commissioning begins after construction start in Q2 2027, and no net-gain is claimed before FOAK first tritium (~2030).