Simple relations between scrape-off layer parameters of high recycling divertors Part I: The relation between `upstream' density and temperature
Bibliographic record
Abstract
It has been found that values of n eu and T eu in the SOL of single null, high recycling divertor discharges in JET and Alcator C-Mod are related approximately as T eu ∝ n eu 1/2 , where (T eu ,n eu ) are the values of plasma temperature and density on any given flux tube at the `upstream' end, for example, halfway between the two targets. Using the standard two point model for the high recycling (conduction limited) divertor, this result is shown to be directly related to criteria based on plasma collisionality - which have to be satisfied if the flux tube is to be in the conduction limited (high recycling) regime rather than the sheath limited (low recycling) regime or the detached regime: the (T eu , n eu ) points for conduction limited flux tubes are predicted to fill a (somewhat narrow) band in the (T eu , n eu ) plane. Secondly, a tendency for the collisionality, as calculated for upstream conditions, to remain constant across the SOL is noted and an explanation is given. The latter then implies a tendency for T eu ∝ n eu 1/2 , to hold, not just at the separatrix but across the SOL. Thirdly, for the JET data a further re-enforcing factor tending to cause a rather strong T eu ∝ n eu 1/2 correlation is identified in the dependence of χ SOL ⊥ on the plasma parameters. The values of χ SOL ⊥ were extracted from the JET data using an onion skin method analysis. The first effect is expected to be general to tokamaks operated in the high recycling/conduction limited regime, although it only states that (T eu , n eu ) values will fall within a certain band, and a decreasing value of T eu with increasing n eu is not ruled out. It is not known at this time how general the second two effects are.
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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 | 0.000 |
| Scholarly communication | 0.001 | 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".