Materials
- scandate / tungsten-based emitter context
- W/Mo refractory metals
- ceramics and brazed interfaces
- contamination sensitivity
Electrical
- ignition and breakdown voltage
- keeper/discharge V-I
- restart repeatability
- long-duration drift
Thermal / vacuum
- emitter and body temperature
- propellant flow
- chamber pressure
- facility background
Diagnostics
- OES erosion indicators
- plasma potential context
- post-test inspection
- endurance log
Validation matrix
| Stage | Controlled variables | Measured record | Acceptance question |
|---|---|---|---|
| Thermal preparation | ramp, soak, vacuum, material compatibility | temperature and pressure history | Was the emitter activated without contamination or overheating? |
| Ignition / start | gas flow, bias, anode distance, power sequence | start voltage, delay, current trace | Is ignition repeatable? |
| Emission stability | operating point, pressure, thermal state | I-V curve, drift, noise, thermal data | Is the cathode stable at target current? |
| Restart cycles | cool-down, vacuum history, exposure time | restart count and parameter shift | Does performance recover after cycling? |
| Endurance | duration, current, gas, contamination control | current drift, voltage drift, visual/post-test inspection | Is degradation rate acceptable? |
Typical diagnostic split
Electrical
I-V curves, current stability, noise, pulse behaviour and restart repeatability.
I-V curves, current stability, noise, pulse behaviour and restart repeatability.
Thermal
heater/input power, temperature estimate, thermal path and radiative losses.
heater/input power, temperature estimate, thermal path and radiative losses.
Vacuum/gas
base pressure, gas purity, flow stability, outgassing and contamination.
base pressure, gas purity, flow stability, outgassing and contamination.
Post-test
emitter surface, deposits, dimensional changes and material compatibility.
emitter surface, deposits, dimensional changes and material compatibility.