Kinetic simulation of secondary electron emission effects in Hall thrusters
Bibliographic record
Abstract
The particle-in-cell code has been developed for kinetic simulations of Hall thrusters with a focus on plasma-wall interaction. It is shown that the effect of secondary electron emission on wall losses is different from predictions of previous fluid and kinetic studies. In simulations, the electron velocity distribution function is strongly anisotropic, depleted at high energy, and nonmonotonic. Secondary electrons form two beams propagating between the walls of a thruster channel in opposite radial directions. The beams produce secondary electron emission themselves depending on their energy at the moment of impact with the wall, which is defined by the electric and magnetic fields in the thruster as well as by the electron transit time between the walls. The condition for the space-charge-limited secondary electron emission depends not only on the energy of bulk plasma electrons but also on the energy of beam electrons. The contribution of the beams to the particles and energy wall losses may be much larger than that of the plasma bulk electrons. Recent experimental studies may indirectly support the results of these simulations, in particular, with respect to the electron temperature saturation and the channel width effect on the thruster discharge.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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 source (direct Gemma or distilled Codex), 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".