Impact of the radial electric field on plasma instabilities in a penning discharge: Insights from a 3D particle-in-cell model
Bibliographic record
Abstract
This Letter describes the main features of the azimuthal and axial structures in a numerical model of a 3D low-pressure magnetized plasma column (a so-called Penning discharge). The simulations are performed with a 3D/3V explicit momentum conserving Particle-In-Cell (PIC) algorithm with Monte Carlo Collisions (MCC). The discharge is seeded by an electron beam injected on one end of the cylinder, ionizing helium atoms for gas pressures of mTorr-scale. We study how the magnetic field strength and a bias voltage on the column's end plates affect the radial electric field profile and the formation of rotating plasma instabilities. We observe kHz-scale rigid rotating structures localized azimuthally (so-called spokes) in the non-linear saturated regime when E·∇n>0 and large m-modes azimuthal waves in the ∼1 MHz range when E·∇n<0. Axial modes in the direction parallel to the magnetic field lines are also observed, which are weakly correlated with azimuthal modes but related to the non-linear plasma-beam instabilities.
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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 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".