Dynamics of magnetic islands and confinement transitions in TJ-II
Bibliographic record
Abstract
Bolometric observations over a large number of discharges under very different conditions in the TJ-II Heliac, together with magnetic and line-emission diagnostics have indicated that the plasma behavior near rational magnetic surfaces is rather peculiar, which involves the formation and destruction of internal transport barriers associated with magnetohydordynamic (MHD) activity [1]. The interpretation of the results is that around the magnetic islands that appear at resonant low-order rational surfaces there is a sheared flow that gives rise to the formation of a transport barrier, as the anomalous transport is decreased. This is evidenced by low recycling at the edge shown by low Ha emission. Then an MHD event arises, possibly due to magnetic reconnection, which destroys the barrier and releases high-energy particles. This sequence of events is observed as sawtooth-like oscillations in the bolometric emission with a well defined repetition time. In this work a model is presented where this ingredients are incorporated in a transport simulation that includes a turbulence model based on resistive ballooning modes [2]. The sheared flow is described by a neoclassical modeling of the ambipolar electric field given in [3]. A transition model [4] is included in the transport system of equations to verify that the appropriate signals are caused by the mechanisms described above. It is found that the model reproduces in an acceptable way the experimental results, supporting the assumed phenomenology: confinement regulated by rapid particle expulsions related to the break of magnetic islands locally and intermittently. The repetition rates are on the ms timescale. The breaking of magnetic islands is described in terms of a magnetic reconnection model which is related to the presence of sheared flows just outside the islands. The unstable tearing mode includes the effect of the polarization drift in the outer region.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| 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) | 0.001 | 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".