Characterization of the flowing afterglows of an N<sub>2</sub>–O<sub>2</sub>reduced-pressure discharge: setting the operating conditions to achieve a dominant late afterglow and correlating the NO<sub>β</sub>UV intensity variation with the N and O atom densities
Notice bibliographique
Résumé
The flowing afterglow of an N 2 –O 2 discharge in the 0.6–10 Torr range is examined in the perspective of achieving sterilization of medical devices (MDs) under conditions ensuring maximum UV intensity with minimum damage to polymer-based MDs. The early afterglow is shown to be responsible for creating strong erosion damage, requiring that the sterilizer be operated in a dominant late-afterglow mode. These two types of afterglow can be characterized by optical emission spectroscopy: the early afterglow is distinguished by an intense emission from the 1st negative system (band head at 391.4 nm) while the late afterglow yields an overpopulation of the v ' = 11 ro–vibrational level of the N 2 ( B ) state, indicating a reduced contribution from the early afterglow N 2 metastable species. We have studied the influence of operating conditions (pressure, O 2 content in the N 2 –O 2 mixture, distance of the discharge from the entrance to the afterglow (sterilizer) chamber) in order to achieve a dominant late afterglow that also ensures maximum and almost uniform UV intensity in the sterilization chamber. As far as operating conditions are concerned, moving the plasma source sufficiently far from the chamber entrance is shown to be a practical means for significantly reducing the density of the characteristic species of the early afterglow. Using the NO titration method, we obtain the (absolute) densities of N and O atoms in the afterglow at the NO injection inlet, a few cm before the chamber entrance: the N atom density goes through a maximum at approximately 0.3–0.5% O 2 and then decreases, while the O atom density increases regularly with the O 2 percentage. The spatial variation of the N atom (relative) density in the chamber is obtained by recording the emission intensity from the 1st positive system at 580 nm: in the 2–5 Torr range, this density is quite uniform everywhere in the chamber. The (relative) densities of N and O atoms in the discharge are determined by using the actinometry method: the density of N atoms decreases from its maximum value at 0% O 2 as the percentage of O 2 is increased while the density of O atoms increases, almost linearly, as a function of the percentage of O 2 , as in the afterglow. The intensity variation of the NO β UV emission as a function of the percentage of O 2 is characterized by a maximum around 0.6% O 2 (2 Torr) followed by an approximately exponential decay. We observe that, in the 0–1% O 2 range, the UV emission is limited by the availability of O atoms. Beyond this point, the decrease of the UV intensity follows the decrease in the N atom density, while on the average, the O atom density keeps on increasing with O 2 %. Erosion of polymer microspheres is found to be strongest at the chamber axis when no O 2 is present, implying a dominant early afterglow. Adding even only 1% O 2 causes a strong quenching of the N 2 metastable species, leading to a dominant late afterglow and therefore considerably reducing the etching rate at the axis. In contrast, at 5 cm from the axis under the same operating conditions, a dominant late afterglow prevails; in the absence of oxygen, erosion is negligible, but it increases regularly as O 2 is introduced, following approximately the increase in the O atom density.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».