On the Validation of Porous Nickel as Substrate Material for Electrospray Ion Propulsion
Bibliographic record
Abstract
The use of nickel as a substrate when creating porous metal Ionic Liquid Ion Source (ILIS) arrays for spacecraft propulsion has been explored and deemed viable. Nickel has been selected as a candidate material due to its compatibility with an electrochemical etching process specifically developed to yield surface micromachining of bulk porous metals without significant pore degradation. The investigation of nickel ILIS includes externally wetted emitters which were fabricated and compared with more common tungsten emitters. Using externally wetted emitters, beam currents measuring 100’s of nA were detected for both positive and negative emission from two ionic liquids, EMI-BF 4 and EMI-Im. The emission from EMI-Im was tested by time of flight spectrometry where it was confirmed that, under most conditions, the emission is purely ionic. In addition, the ionic liquid to nickel interface potential was probed during emission from externally wetted emitters. Here it was found that by alternating the emission polarity at frequencies on the order of 1 Hz , complete charging of the electrochemical double layer can be prevented. Combined with similar results from tungsten emitters it is motivated that detrimental electrochemical effects can therefore be suppressed through voltage alternation. The process implemented for electrochemically fabricating porous nickel ILIS arrays is presented along with a process for housing the array within a silicon enclosure which includes an aligned electrostatic grid. Finally, emission characteristics from a sample array of porous nickel ILIS are presented. Between 100 and 150 emitters fabricated on a 10 x 10 x 1 mm porous nickel wafer were fired yielding current levels up to 200 µA .
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".