Creating negative ion beams from neutral gases using a negative hydrogen ion source
Bibliographic record
Abstract
Abstract A typical method to produce negative ion beams uses alkali vapour as a medium for a double charge exchange to convert incident positive (1+) beams to negative (1-) beams. Alkali vapours pose a problem in ion production as they are flammable, explosive and cause vacuum surface contamination. Thus, it is advantageous to use non-metallic vapours for charge exchange as it will prevent hazards and the contamination of vacuum surfaces and targets in which the negative ion beams are incident upon. In this paper we will describe and demonstrate the process of creating negative ion beams by impinging a 15 keV to 30 keV beam from D-Pace's TRIUMF licenced H- volume-cusp ion source (1 mA to 15 mA) onto a volume of non-metallic neutral gas (X) resulting in a single or two-step charge exchange: H- + X → H + X- or H- + X → H + X + e → H + X-. The newly created X- ion beams will be accelerated by a (1 to 20) kV electrostatic accelerator and passed through a mass spectrometer system to separate the primary H- beam from the X- beam. The two gases studied are He and H2 and we will present the magnitude of the resultant beam currents after being separated from the incident H- beam by the mass spectrometer system.
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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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".