Turbulent excitation of plasma oscillations in the acoustic frequency range
Bibliographic record
Abstract
The impact of geodesic curvature on flux-driven electrostatic ion temperature gradient turbulence in the core of tokamak plasmas is studied by means of three-dimensional fluid global numerical simulations. The emphasis is on the dynamics of the axisymmetric fluctuations. The simulations evolve the equilibrium and the perturbed fields as a whole. The coupling of poloidal harmonics induced by the curvature results, on the one hand, in the presence of neoclassical transport, besides the turbulent one, and on the other, in the generation of oscillations in the acoustic frequency range. The neoclassical thermal conductivity is evaluated for the considered isotropic model, and scales as the plateau conductivity. The computed conductivity is shown to agree perfectly with that theoretical estimate. Geodesic acoustic modes (GAMs) are only observed transiently in the simulations. The GAM oscillations are strongly reduced in the final turbulent stationary state. The main peak in the poloidal velocity spectra is observed at a lower frequency. Detailed analysis of the simulations in the turbulent stationary state, in particular by means of a singular value decomposition of the space-time data, shows that a second linear branch of axisymmetric modes, having a frequency somewhat lower than the acoustic one, is more effectively excited by the turbulence. The result is a quasicoherent mode with a radial wavelength somewhat larger than the ion Larmor radius.
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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) | 0.002 | 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 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".