Improvements to a 13.56 MHz RF powered H− ion source
Bibliographic record
Abstract
D-Pace’s 13.56 MHz RF powered H− ion source, a hybrid design between the TRIUMF licensed filament powered volume-cusp ion source and the University of Jyväskylä licensed RF ion source, has been shown to be less efficient than the filament powered ion source, even though both sources use the same body and extraction system. The difference is thought to be due to RF power losses to the outside of the ion source, to the lack of plasma confinement on the back plate of the ion source, and to the absence of a sputtered tantalum coating on the plasma chamber walls. We believe that the lack of confinement on the back plate also causes the RF window to heat, with a maximum temperature measured at 450 °C at 3.5 kW of RF power. In this paper, we are investigating the use of a solenoid and permanent magnets behind the antenna and the back plate of the ion source to create a magnetic field that confines the plasma by preventing the electrons from striking the RF window. Furthermore, we present the effect of sputtering a tantalum coating in the plasma chamber of the ion source on the production of H− ions in the RF powered source. Our results show an increase in H− beam current at higher RF powers with a fresh coat of tantalum, and a subsequent decrease in beam current over time.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.003 |
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".