Control System

Hardware integration (Step 3.6)

Install the PLC or compact industrial controller along with IO modules, SSRs/contactors, and hardwired interlocks. Map door, panel, over-temperature, and vacuum-OK signals before energizing heaters.
Mount two-color pyrometers with purged sight tubes aimed at the melt zone and refining pot. Verify both channels read correctly from room temperature through a controlled heat soak.
Position the LIBS head above the feed inlet or melt surface using a windowed port. Route the fiber bundle to the gated spectrometer and perform alignment shots on inert targets before live material.
Aim the OES fiber toward the electrode/plasma zone to resolve Fe, Si, and O emission lines. Confirm shielding prevents stray light or arc flash from saturating the detector.
Connect the RGA to the refining foreline via a throttled tee downstream of the cold-trap. Calibrate mass peaks during a dry pump-down to establish baselines.

Implement permissives that block heater enable until all door, panel, vacuum, and coolant interlocks report safe states.
Use PID loops for heater zones with ramps/soaks tailored to the target temperatures in each process stage.
Log critical parameters (temperatures, currents, spectra, pressures) at intervals sufficient for later analysis and troubleshooting.

Preheat the MOE cell to 1600 °C and hold for 20 min to stabilize the thermal mass.
Verify LIBS feed characterization meets recipe limits; abort if out of bounds.
Enter the Fe window: apply low cathodic overpotential/current density and watch OES lines until the iron sump mass threshold is met. Tap or park the iron as required.
Transition to the Si window: increase potential by 10–20 % compared to the Fe stage, monitor silicon emission growth, and manage the headspace to keep Fe isolated.
Transfer molten silicon to the refining pot. Initiate vacuum refining once ≤10 Pa is reached and continue until the RGA shows phosphorous species below threshold.
Command the casting sequence, cool under control, and record spectra/logs for post-run review.

Dry-run the full control sequence without feed to validate interlocks, sensor scaling, and data logging.
Inject known spectral lines (calibration lamps or reference targets) to confirm LIBS/OES wavelength accuracy before production runs.
Simulate an emergency stop to confirm all heaters and motion drives default to safe states while maintaining data capture.