Diagnostics Data Acquisition
Data acquisition converts physical signals from plasma diagnostics into digital records with known timing, scaling, and uncertainty.
From signal to sample
A fusion device is instrumented with diagnostics: magnetic probes, interferometers, spectrometers, bolometers, neutron detectors, and more. Each produces an analog signal that a data acquisition (DAQ) system amplifies, filters, and digitizes into numbers stamped with time. The quality of everything downstream depends on getting this stage right.
The digitization chain
- Front-end conditioning: amplification and anti-alias filtering match the signal to the digitizer input.
- Sampling: an analog-to-digital converter samples at a fixed rate; by the Nyquist rule the rate must exceed twice the highest frequency of interest.
- Quantization: each sample is stored with finite bit depth, setting the smallest resolvable step.
- Timestamping: every sample carries a time reference from a shared clock.
Timing and synchronization
Diagnostics must share a common time base so signals can be compared. A central timing system distributes triggers and a clock; channels record relative to a shot start. Without synchronization, correlating a density spike with a magnetic event is impossible. See DAQ triggering and timing.
Calibration
Raw counts are meaningless until mapped to physical units through calibration: gain, offset, and channel-specific response. Calibration data is itself a dataset that must be versioned and stored beside the measurements, because a recalibration changes the interpretation of every past shot. See sensor calibration data.
Volume and rates
High-speed diagnostics can generate large bursts during a plasma pulse. DAQ systems buffer locally, then transfer to storage between shots. For the Hyperion breeder design, acquisition architecture is specified in simulation now; the physics targets it must eventually resolve include the Q 3.424 operating point and the current and field profiles of the design.
Because current Kronos machines are design and simulation rather than built hardware, DAQ appears today as modeled channel behavior and as the format contracts that future instruments will fill.