Supersonic plasma jets formed by DC arc and ICP torch: common features and differences
Bibliographic record
Abstract
Summary form only given. Some new techniques using remote thermal plasma for plasma chemistry and plasma processing have been developed. These techniques include plasma spraying, PECVD of diamonds, diamond-like and polymer films. In remote plasma deposition, thermal plasma is formed by means of one of traditional plasma sources. The chamber pressure is reduced with the help of continuous pumping. In that way the flow is accelerated up to the supersonic speed. The plasma expansion is controlled using a specific torch nozzle design. For practical applications it is very important to find the parameters that determine the gas dynamical and physical properties of supersonic plasma flows. With this aim, we analyze the common features and the differences between supersonic jets of plasma formed by direct current arc and induction torch. The plasmas flowing from the DC and ICP torches with slightly sub-atmospheric pressures through the supersonic nozzles (with the outlet Mach numbers 1 and 1.5) into low-pressure (2kPa) chambers are compared. The analysis is performed by means of optical emission spectroscopy combined with the numerical modeling. In our simulations we incorporate user-defined subroutines for two-temperature model into commercially available FLUENT program. The results show that substantial interrelated deviations from thermal, ionization and Boltzmann equilibrium can be found in both jets. We demonstrate that the ratio of the static pressure at the chamber inlet to the chamber pressure together with the Mach number at the nozzle outlet and the rarefaction parameter define the supersonic jet structure, and not the chamber pressure alone. We show that the physical properties of supersonic plasmas depend on the way and place of plasma formation. Namely, it is important to distinguish the configurations where the plasma is firstly formed and then accelerated (as in ICP torch) and the configurations where the plasma is formed and accelerated at the same time (as in DC arc). The obtained results are useful for the optimization of plasma reactors for plasma chemistry and plasma processing applications.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".