Digital Twin Architecture

A twin is a layered federation: sensing and ingestion, a physics or surrogate core, an assimilation loop, and a decision and interface layer.

Layers of a twin

A working twin is not a single program but a layered federation of components, each with its own update rate, ownership, and failure behavior. Separating the layers keeps the fast control-relevant parts independent of the slow analytics, so a slow analysis never stalls a real-time loop.

Sensing and ingestion

Sensors and diagnostics produce raw signals; the ingestion layer timestamps, calibrates, validates, and buffers them. It rejects bad channels, aligns clocks, and presents clean measurement vectors to the estimator. For a fusion machine this layer must handle wildly different rates, from magnetic pickup coils sampled thousands of times per second to neutron activation samples analyzed between campaigns.

Model core

The core holds the physics: full-fidelity codes for offline use and surrogate models fast enough for the loop. It advances the estimated state and produces predicted observations to compare against real ones. See surrogate models.

Assimilation loop

The assimilation layer fuses model predictions with incoming measurements to maintain a best current state estimate with quantified uncertainty. This is where a Kalman or ensemble or particle filter lives. It is the heart that makes the federation a twin rather than a simulator. See data assimilation.

Decision and interface

The top layer turns state estimates into value: what-if studies, control recommendations, maintenance forecasts, and operator displays. It may feed a model-predictive controller or simply advise humans. See twin-in-the-loop control.

Cross-cutting concerns

• Timing and determinism for the real-time path
• Data standards so components interoperate
• Security across the sensor-to-actuator boundary
• Versioning so every prediction is traceable to model and data provenance

Kronos builds this architecture around both machines. The breeder Hyperion and the burner share the pattern but differ in the physics carried in the core, because a spherical tokamak and a tandem-mirror generator have different dominant behaviors.