Experimental Studies of Fluctuations and Turbulences in the STOR-M Tokamak and TJ-II Stellarator
Bibliographic record
Abstract
Experimental studies of the fluctuating flux and turbulences have been active topics in the tokamak research in order to improve plasma confinement purposes. The electrode biasing and wall conditioning have crucial effect on the plasma transport and fluctuating flux suppression at the edge region of the plasma. Electrode biasing involves a modification on the edge radial electric field which in turn generates shear drift that suppresses the plasma fluctuations. The electrode biasing experiment is carried out in the Saskatchewan Torus-Modified (STOR-M) tokamak using an arc-shaped electrode. Different biasing voltage waveforms have been applied with and without lithium (Li) coated walls. In DC electrode biasing experiment, when the electrode was biased at -390V a change in flux direction from outward to inward in addition to increase plasma density have been observed. Also, a suppression in the fluctuating flux with changing in its direction to inward due to the phase decorrelation between the plasma density and poloidal electric field fluctuations is noticed. Conducting DC-biasing experiment with Li coating gives strong evidence of edge transport formation at radial location where the plasma temperature and density increase significantly, and flux direction is reversed to inward. In bi-polar multi-pulse biasing experiment, a suppression in the fluctuating flux is noticed also during the negative biasing pulses. Also, the suppression in the flux turbulences has been observed in the low frequency and quasi-coherent modes frequency ranges. DC electrode biasing has been applied with resonant magnetic perturbation (RMP) since RMP has favorable effects on magnetohydrodynamic (MHD) stabilities. Application of both electrode biasing and RMP supresses the magnetic fluctuations in addition to the fluctuating flux which increase the plasma confinement. Moreover, the electrode biasing experiment has been conducted during the neutral beam injection in the TJ-II stellarator. The suppression in the fluctuating flux during the negative biasing pulses (-370V) is noticed. Also, the direction of energy propagation or floating potential fluctuation propagation in TJ-II has been studied using the non-linear correlation analysis. In TJ-II, during application both NBI and negative electrode biasing pulses, the energy propagation direction is revered from outward to inward as an indication of improved plasma energy confinement.
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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 | 0.000 |
| 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".