On the Origin of Donut‐Shaped Electron Distributions Within Magnetic Cavities
Bibliographic record
Abstract
Abstract Magnetic cavities, also known as magnetic holes, are ubiquitous in space plasmas characterized by depressed magnetic strength and enhanced plasma pressure. Most of the observed cavities are associated with anisotropic particle distributions with higher fluxes in the direction perpendicular to the magnetic field. Recent observations of kinetic‐scale magnetic cavities have identified another type of electron distributions in the pitch angle spectrum, the so‐called donut‐shaped distributions, although their formation mechanism remains unclear. Here, we present a simplistic model of cavity shrinkage and deepening, in which electrons are traced backward in time to the initial, equilibrium‐state cavity. The resulting electron distributions, determined from Liouville's theorem, agree with the observations in the presence of donut‐shaped pitch angle structures. The model also enables a quantitative evaluation on the roles of betatron cooling, radial transport, and pitch angle variations in the formation of donut‐shaped electron distributions within evolving magnetic cavities.
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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 | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".