DEC Control & Tuning

Real-time control keeps every stage matched to a changing beam, holding the recovery fraction high as plasma conditions drift.

A converter that must stay matched

The efficiency of the DEC train depends on matching — the RF phase to the ion velocity, the collector bias to the arrival energy, the MHD load to the flow, the suppressor to the electron population. But the beam is not perfectly steady: plasma conditions drift, so a converter tuned for one moment is mismatched the next. A real-time control system continuously re-tunes each stage to hold the match.

What is sensed and what is actuated

• Sensed: beam current and energy spectrum, surface temperatures, MHD channel conductivity, bus voltage, stage currents.
• Actuated: collector and suppressor biases, RF amplitude and phase velocity taper, MHD load impedance, inverter setpoints.
• Objective: maximize recovered power to the bus while respecting heat and voltage limits.

Where models help

Because the converter has many coupled knobs, the control system leans on fast models of the train to predict how a change in one stage affects the next, rather than tuning each blindly. This is the same predictive-control philosophy the Kronos program applies to the plasma itself: measure, predict, and adjust faster than the system drifts. It keeps the recovery fraction near its design value across operating conditions.

Firmness through control

Good control is what turns a set of finicky converters into a firm generator. It absorbs plasma drift, coordinates the stages so one does not spoil another, and manages the handoff to the grid interface. Along with the startup and transient design, it is what lets MetroVolt deliver steady output despite the inherently variable source — all as a design-stage concept ahead of the ~2032 test unit.