Diagnostic of vacuum subsonic and supersonic plasma flows with enthalpy probe, schlieren and high speed camera methods
Bibliographic record
Abstract
Summary form only given. HF plasma has been used for numerous applications. HF plasma of subsonic flow is used for densification and spheroidization of powders, thermal protection deposition and liquid and gaseous waste destruction. As for HF plasma supersonic flow, in spite of its less frequent use, its diagnostic is crucial in order to improve processes involving this type of plasma. Recently, HF plasma of supersonic flow has been used for the synthesis of nanometric powders and since many years, this plasma simulates ionized gas that space crafts encounter during their re-entry in the atmosphere. Thus, in this study, three diagnostic tools are used to acquire complementary information on HF vacuum plasma of subsonic and supersonic flows. The plasma jet is generated by a PL-35 induction plasma torch operating with two convergent-divergent Laval nozzles giving velocities around Mach 1.5 and Mach 3.0 and lower velocity when a subsonic nozzle is used. The plasma plate power and chamber pressure are fixed at 20 kW and under 60 torrs respectively. The plasma is made of argon and also of argon and 4% hydrogen. The first diagnostic tool is the enthalpy probe which measures enthalpy and stagnation pressure of the plasma and afterward, local plasma velocity and temperature are calculated. Completed axial and radial temperature and velocity profiles have been measured. The second tool, the Schlieren photography, is an optic system based on density gradient detection inside the plasma jet. Actually, because of the low chamber pressure and consequently the low plasma density, Schlieren photography of vacuum supersonic plasma jet is quite difficult, so this study will described the application limits of the Schlieren photography. The last tool is a high speed camera that gives relevant photographs about the stability and behaviour of the plasma jet. Photographs with different exposure times from 10 /spl mu/s to 1 ms reveal that supersonic plasma jet is stable. Also, subsonic plasma jet photographs taken with an exposure time of 100 pm show that plasma jet stability and specific energy are affected by the central gas flow and the chamber pressure. All this diagnostic of plasma jet behaviour is evaluated against plasma condition parameters in order to improve diagnostic and applications involving HF plasma.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 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".