IMPACT PRESSURE MEASUREMENTS OF MODIFIED LAVAL NOZZLE GEOMETRIES
Bibliographic record
Abstract
Over 270 distinct molecules have been detected in the interstellar medium (ISM).Chemical kinetics models are used to elucidate the formation mechanisms of these species under astrophysical conditions, and these models require accurate temperature-dependent rate coefficients for gas-phase reactions.The combination of laser-induced fluorescence (LIF) with uniform supersonic molecular beams (i.e., CRESU) has proven to be a powerful method for measuring total rate constants.In recent years, there has been considerable interest in coupling chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy with the CRESU method, but the high density environment of the uniform flow causes rapid rotational dephasing, dramatically limiting its sensitivity.The Suits group at the University of Missouri-Columbia has proposed the design of an extended nozzle which contains the uniform flow, followed by a free-jet expansion where CP-FTMW spectroscopy may be employed.However the use of a nozzle extension prevents optical access to the uniform flow, complicating LIF measurements.Here, we discuss the incorporation of a fiber optic access port within the nozzle extension to provide in situ LIF measurements.Pitot tube impact pressure measurements were recorded to assess flow uniformity for solid extended nozzles, an extended nozzle with a hole, and a nozzle outfitted with a fiber optic collimator, for He and Ar nozzles spanning a range of temperatures.The effects of flow perturbation and the prospects for in situ fluorescence measurements will be discussed.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".