Fluorescent thermal imaging of a quench in insulated and non-insulated REBCO-wound pancake coils following a heater pulse at 77 K
Bibliographic record
Abstract
Abstract High temperature superconductors (HTS)-wound coils are being developed for use in motors, generators as well as magnet applications. Determining the stability and safe operating margins of such coils still poses challenges. While the recently introduced no-insulation winding method provides a remedy for many problems, it comes with its own limitations. For comparison, we have wound two pancake coils from HTS coated conductors with the insulated and non-insulated winding techniques. Both coils were coated with a fluorescent, temperature-sensitive coating, which allowed monitoring the surface temperatures during operation. The coils were cooled to 77 K via a combination of conduction and gas cooling, and their electrical and thermal behaviour was observed in operation. Here we present the normal transition of both coils caused by an artificially introduced instability due to a surface-mounted, resistive heater element. In the insulated coil, the localized disturbance caused a local transition of the superconductor to the normal conducting state, triggering a thermal runaway. Merely the turns in contact with the artificial disturbance heated up, while the rest of the coil remained in the superconducting state. In the non-insulated coil—although a much longer heater pulse was required—the normal transition started from the weakest point of the coil (around the bobbin) and the whole coil was heating thereafter, with the centre heating more.
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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) | 0.002 | 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 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".