PF and CS Coil Supply Interface

The poloidal-field and central-solenoid supplies are the breeder's shape and position actuators, driven by MPC and clamped by the field envelope.

Role in the breeder

On Hyperion the poloidal-field (PF) and central-solenoid (CS) coils set plasma position, elongation, and the negative triangularity δ = −0.30. The supply interface converts shape-MPC coil-current trajectories into regulated currents while respecting slew and cross-coil field limits.

Command and feedback

# shape MPC output -> PF/CS supply interface
I_coils = shape_mpc(shape_meas, shape_ref, twin)   # L3
for k in pf_cs_coils:
    supply[k].command(I_coils[k], dIdt_max[k])     # L1
# feedback: measured coil currents + reconstructed boundary
shape_meas = equilibrium_recon(flux_loops, mirnov)

The interface is multivariable: a single triangularity change moves several coils together, and the same coils also hold vertical position. Allocation and slew reserve are handled inside the MPC weighting so no coil is driven to its limit without margin.

Coupling to stability

• Vertical stability runs faster (kHz) on the radial-field coil and can pre-empt slow shape moves.
• Boundary reconstruction from magnetics closes the loop.
• Peak-field checks share the REBCO command interface envelope.

Owner: L1 for the regulated current loop; L3 for the setpoint trajectory. Timing: shape in tens of ms, vertical stabilization sub-ms. Negative triangularity is a shape target the interface must hold accurately because it is central to the breeder's edge-stability strategy. Design-and-simulation specification, exercised against the twin ahead of Q2 2027 construction start.