Nonlinear simulations and anomalous transport in hall thruster plasma
Bibliographic record
Abstract
Summary form only given. The plasma inside a Hall thruster is a complex environment full of instabilities and interesting physical phenomena such as anomalous transport. To better understand this complex plasma dynamics, a nonlinear fluid model has been developed. The model contains the effect of electron inertia, electron collisions, electron temperature and density gradients as well as nonlinearities in the ion velocity and the electron advection term that arises from the ExB drift. The model is simulated using BOUT++, a framework for plasma simulations developed at the Lawrence Livermore National Laboratory. The linear limits of the model correspond to the lower hybrid mode rendered unstable by collisions and to the density gradient drift instabilities. Two cases are simulated using BOUT++, one without density gradients and one with density gradients. Both these cases exhibit energy saturation as well as an axial current much larger than the classical collisional value. The simulations with density gradients seem to show a larger axial electron current as well as exhibiting azimuthally propagating structures similar to the spokes observed experimentally.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".