Accueil Imprimer Annuaire Plan du site Crédits Fil RSS du site Twitter LinkedIn Plans d'accès Contacts Annuaire Webmail Intranet outils & logiciels Logo

Accueil > A propos du LPP > Communication > Actualités archivées > 2020 > New and efficient pathways for N2 dissociation using high energy density low-temperature plasmas

New and efficient pathways for N2 dissociation using high energy density low-temperature plasmas

Toutes les versions de cet article : [English] [français]

The mechanism of N2 dissociation has been a well-studied research topic both from a basic science perspective and for its relevance to industrial applications such as nitridation, synthesis of large band gap nitrides for electronics, as well as biomedical treatment. The enduring challenge for these industries has been to figure out novel ways of elevating this dissociation yield.

Commonly known pathways for the production of N-atoms in plasma include electron impact dissociation of ground state N2 molecules, as well as the dissociation of electronically and vibrationally excited N2 molecules. Recent research at LPP within the ANR ASPEN Project has found that nanosecond pulse, high energy density discharges may offer an interesting approach to achieving efficient N2 dissociation. While nanosecond pulse plasmas have gained widespread attention for their ability to produce extremely high electric fields, further increasing the specific energy coupled to these plasmas via a miniaturization of the discharge cell volume (Fig.1), has proven to be an exciting area of research. In particular, the large amount of reactive species produced by this unique subset of nanosecond discharges has a profound effect on the consequent plasma chemistry.
Figure 1

By probing a nanosecond pulse capillary discharge with a laser-based diagnostic known as two-photon absorption laser induced fluorescence (TALIF), we find that high levels of N2 dissociation (about 10%) are realized (Fig.2 (a)), at a moderate working pressure of about 30 mbar. Measured energy efficiency, or G-factor (Fig.2 (b)) is as high as GN=10 atom/100 eV (i.e. 10 atoms of nitrogen per 100 eV of deposited energy).

Figure 2

Modelling efforts, performed in the framework of the French-Russian collaboration (LIA KaPPA) at Moscow State University, reveal that a possible pathway driving this efficient source of N-atoms, is the existence of a complementary stepwise dissociation process. As shown in Fig. 3, conventional dissociation of ground state N2 molecules occurs through electron impact to high-lying predissociative levels of N2. In the case of stepwise dissociation, these predissociative levels are more efficiently populated through an additional transition via the N2(A,B,C) states. This additional ‘pool’ of electronically excited N2 molecules is a direct consequence of the high specific energy coupled to the capillary discharge (2 eV/molecule).

Figure 3

This study provides a strong incentive for the further study of these high energy density pulse discharges both from a plasma chemistry standpoint, as well as an efficient source of molecular dissociation.

Voir en ligne : https://iopscience.iop.org/article/...

Dans la même rubrique :


transparent
CNRS Ecole Polytechnique Sorbonne Université Université Paris-Saclay Observatoire de Paris
transparent
©2009-2025 Laboratoire de Physique des Plasmas (LPP)

Mentions légales
Exploitant du site : Laboratoire de Physique des Plasmas, Ecole Polytechnique route de Saclay F-91128 PALAISEAU CEDEX
Hébergeur : Laboratoire de Physique des Plasmas, Ecole Polytechnique route de Saclay F-91128 PALAISEAU CEDEX
Directeur de la publication : Anne Bourdon (Directrice)

Accessibilité