Decision point → system boundary → dominant balance → measurement data → conclusion.
| Step | Engineering item | Required definition | Output |
|---|---|---|---|
| 1 | Decision point | equipment acceptance, supplier comparison, process transfer, failure analysis, or test readiness | review target |
| 2 | System boundary | chamber, pump train, hot zone, plasma source, treated surface, cathode, or full test bench | model domain |
| 3 | Dominant balance | gas load, effective pumping speed, diffusion, heat transfer, ion flux, or emission stability | reduced calculation |
| 4 | Measurements | pressure-time curve, leak test, temperature log, profile, cross-section, I-V data, or test coupon | data request |
| 5 | Conclusion | accepted, conditionally accepted, rejected, or returned for additional measurement | technical memo / FAT question / test plan |
| System | Boundary | Dominant balance | Primary data | Reject condition |
|---|---|---|---|---|
| Vacuum chamber | vessel + ports + seals + pump connection | gas load vs effective pumping speed | pump-down, pressure-rise, helium leak test | ultimate pressure stated without pressure-time data |
| Process gas system | MFCs + valves + chamber conductance + exhaust | process gas load vs Seff | flow-pressure log | nominal pump speed stated without conductance/gas-load check |
| LPC / carburizing load | steel grade + load geometry + boost/diffusion schedule | carbon diffusion and boundary carbon flux | carbon profile, hardness profile, recipe log | recipe name without measured profile |
| Plasma nitriding | part surface + plasma sheath + fixture + thermal path | ion flux, bias, chemistry and temperature | bias/current log, cross-section, hardness profile | surface-treatment claim without layer/profile data |
| Coating process | substrate + interface + coating + contact environment | adhesion, stress, load support and tribological response | cross-section, thickness, adhesion, tribology | coating photo without functional data |
| Cathode-neutralizer | emitter + insert + thermal path + gas/plasma coupling | emission stability and thermal state | I-V curves, restart cycles, drift data | single ignition event presented as validation |
| TVAC / EP chamber | chamber + pumping + thruster gas flow + diagnostics | gas load vs effective pumping during operation | gas-load pressure, Seff, diagnostic layout | empty-chamber base pressure used as test-condition proof |
After the system boundary is fixed, the review moves to the physical balance that controls the decision.
A vacuum problem starts with gas load, chamber volume and effective pumping speed. A diffusion-treatment problem starts with temperature, material response and boundary carbon or nitrogen flux.
A plasma-treatment problem starts with ion flux, bias, chemistry and surface temperature. A cathode problem starts with thermal state, gas/plasma coupling and emission drift.
The blocks below keep the same structure: variables to define, records to request, and the decision that can be made from those records.
Used when chamber pressure must be checked under pump-down or process gas flow.
| Inputs | V, Q, Seff, conductance, gas species |
| Records | pump-down curve, process-pressure curve, pump data |
| Decision | base-pressure and process-pressure plausibility |
Used when the chamber reaches pressure slowly or cannot hold pressure after isolation.
| Inputs | isolated volume, pressure-rise slope, material state |
| Records | pressure-rise curve, helium leak test, bakeout/cleaning history |
| Decision | leak repair, bakeout, cleaning, or geometry correction |
Used for LPC, carburizing and nitriding when the required result is a measured depth/profile, not only a recipe name.
| Inputs | steel grade, temperature, time, boost/diffusion schedule |
| Records | carbon/nitrogen profile, hardness profile, microstructure |
| Decision | case depth, surface state, recipe transferability |
Used when controller temperature, load temperature and thermal gradients may differ.
| Inputs | heater power, load mass, emissivity, fixture contact, gas state |
| Records | thermal map, ramp/soak logs, TUS/SAT where applicable |
| Decision | thermal uniformity and load-temperature validity |
Used when activation, nitriding, etching or coating adhesion depends on ion energy, flux and chemistry.
| Inputs | pressure, gas composition, bias, current, source geometry |
| Records | bias/current log, witness coupon, profile, roughness |
| Decision | activation, nitriding, etching, adhesion risk |
Used when ignition must be separated from stable operation, restart behaviour and drift.
| Inputs | temperature, emitter state, gas flow, operating current |
| Records | I-V curve, restart cycles, drift, vacuum/gas log |
| Decision | activation quality and operational stability |
| Case | Given | Check | Output |
|---|---|---|---|
| Vacuum chamber acceptance | V, pump train, pressure-time curve, leak-test target, process gas flow | Seff, Q = V·dP/dt, P ≈ Q/Seff, conductance constraints | acceptance questions for leak, outgassing, conductance and gas-load pressure |
| LPC recipe transfer | steel grade, boost/diffusion schedule, target case depth, HPGQ route | carbon profile, hardness profile, surface carbon, quench result | recipe accepted, corrected, or returned for profile measurement |
| Cathode-neutralizer validation | ignition trace, current setpoint, gas flow, pressure, thermal route | I-V curve, drift, restart cycles, post-test state | activation accepted or additional stability test requested |
| PVD/CVD coating route | substrate, contact medium, load, temperature, coating route | interface, thickness, stress/load support, tribology data | route accepted for component test or rejected as insufficiently documented |
| Area | Required records | Engineering conclusion |
|---|---|---|
| Vacuum equipment | pump-down curve, ultimate pressure, pressure-rise curve, helium leak-test report | vacuum integrity and gas-load plausibility |
| Vacuum thermal process | temperature map, ramp/soak log, vacuum/gas log, load description | thermal regime and process repeatability |
| Diffusion treatment | recipe log, carbon/nitrogen profile, hardness profile, microstructure | case depth, surface condition and process transferability |
| Coating | cross-section, thickness, adhesion, roughness, tribology or component test | coating architecture and functional suitability |
| Cathode | I-V data, current drift, restart cycles, vacuum/gas log, post-test inspection | activation quality and operational stability |
| TVAC / EP test | gas-load pressure, effective pumping estimate, diagnostic layout, contamination-control data | test-environment readiness |
Model boundary: chamber volume, conductance, effective pumping speed, gas source and pressure measurement location.
Model boundary: steel composition, temperature history, carbon / nitrogen boundary flux, phase constraints and quench route.
Model boundary: substrate support, interface, layer sequence, residual stress, roughness and contact environment.
Model boundary: emitter condition, temperature, vacuum/gas environment, geometry, current regime and restart sequence.
Numerical diffusion models are part of the technical data for diffusion-controlled phase redistribution, precipitate evolution and thermal-stability assessment in multiphase materials.
Checks: model boundary, diffusion data, time/temperature condition, numerical result, publication list.
Multicomponent coatings exposed to aggressive optical-glass-melting media require chemical-compatibility, dissolution/degradation and interface-stability records.
Checks: coating composition, exposure medium, temperature / process condition, post-exposure microstructure and degradation pattern.
