Deterministic I/O Through Cryo-Rated Feedthroughs

Analog telemetry crosses the vacuum and cryogenic boundary through rated feedthroughs into a fabric front end that samples at sub-microsecond intervals.

Crossing the boundary

Diagnostics live inside a high-vacuum, partly cryogenic environment; the control fabric lives outside it. Signals cross through cryo-rated vacuum feedthroughs engineered to preserve signal integrity while maintaining vacuum and thermal isolation. This physical interface is the first link in the deterministic chain, and its fidelity sets the noise floor for everything downstream.

Front-end sampling

On the outside, each analog line meets an anti-alias filter and an ADC clocked from the shared reference. Sampling instants are aligned across channels so the assembled state is coherent. Conversion latency and filter settling are part of the channel's fixed timing budget, so acquisition contributes a known constant to the loop's WCET.

Signal integrity

• Shielding and differential routing to reject the machine's EM environment.
• Ground discipline to avoid loops through the vessel structure.
• Characterized bandwidth per channel so aliasing is controlled.
• Feedthrough thermal design to keep drift within calibration limits.

The electromagnetic environment near a high-field magnet and a pulsed plasma is hostile; a sloppy front end would inject jitter and noise that no downstream cleverness can remove. Kronos treats the analog front end as a determinism-critical component, not plumbing.

From feedthrough to state

Once digitized and validated, channels flow into state-vector ingress. Because the feedthrough-to-ADC path is deterministic, the whole sensor-to-actuator pipeline can carry a provable end-to-end bound. The same interface class serves the breeder's tokamak diagnostics and the burner's mirror diagnostics; only channel counts and placements differ.