Observation and characterization of discharge mode transition in a three-electrode atmospheric pressure RF plasma system
Bibliographic record
Abstract
Abstract A new 3-electrode plasma device powered by a combined nanosecond pulsed (nsp) source and a sub-breakdown pulsed radiofrequency (RF) source at atmospheric pressure in a N2/H2 (97.5%/2.5%) mixture is studied. By applying pulsed excitation sequences from both the nsp and RF sources, two different RF discharge modes are obtained depending on the actual participating electrode pair. In the RF dielectric-barrier-discharge (RF-DBD) mode, the discharge forms between the RF metallic pin electrode and the nsp electrode located behind a dielectric surface (exterior to the reactor). In the RF pin-to-pin (RF-PtP) mode, the RF discharge forms between the RF and grounded metallic pin electrodes, both located inside the reactor. The existence of the two RF discharge modes is highly dependent on the RF pulse duration as revealed using high-speed imaging along with a custom electrical measurement technique. It was observed that for longer duration RF pulses, RF-PtP mode is achieved through a transition of RF-DBD into RF-PtP mode (DBD-PtP transition). Electrical characterization revealed higher coupled power percentages for RF-PtP mode (up to 85%) over RF-DBD mode (25%–75%). However, deteriorating impedance matching of the RF-PtP mode decreased the available RF applied power thus yielding similar plasma power deposition as RF-DBD mode. Plasma characterization performed by analysing the emission of the N2 second positive system provided vibrational temperatures up to 3400 K and a thermalization trend of the rotational temperatures as RF pulse duration increased. Mechanisms behind the DBD-PtP transition are proposed under consideration of the obtained data. We attribute the observed discharge dynamics to diffusional forces acting on charged species such as ambipolar diffusional drift and diffusional charge flow.
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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 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".