Thermal energy confinement time of spherical tokamak plasmas in PI3
Bibliographic record
Abstract
Abstract The Plasma Injector 3 (PI3) experiment at general fusion has been constructed to demonstrate the ability to form plasma targets suitable for compression in a Magnetized Target Fusion machine. To achieve compressive heating to fusion conditions, the target plasmas should have an energy confinement time sufficiently in excess of the compression time. In this work we present a methodology for calculating this timescale and present results for a large set of discharges. Characterization of the plasma current profiles reveals trends and groupings determined by machine settings. The largest energy confinement times have been obtained for discharges with a broad plasma current profile, fresh lithium coating on the device walls, and a near constant toroidal field. We find that PI3 plasmas at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>5</mml:mn> <mml:mstyle scriptlevel="0"/> <mml:mrow> <mml:mi>ms</mml:mi> </mml:mrow> </mml:mrow> </mml:math> into the discharge can have thermal confinement times in excess of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>10</mml:mn> <mml:mstyle scriptlevel="0"/> <mml:mrow> <mml:mi>ms</mml:mi> </mml:mrow> </mml:mrow> </mml:math> . These meter-scale plasma can thus achieve significant heating if compressed on a timescale of milliseconds.
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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) | 0.364 | 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".