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Accueil > Séminaires et conférences > Séminaires, soutenances de thèses et HDR précédents > 2009 > Séminaires 2009 > Lundi 30 mars 2009 à 14h

Lundi 30 mars 2009 à 14h


Åshild Fredriksen
(University of Tromsø, Norway)

Le lundi 30 mars 2009 14h

Ecole Polytechnique, Bibliothèque LPP

On double layers in the Njord plasma device at the University of Tromsø.

Njord is an inductively coupled plasma device with a 13.56 Mhz RF source coupled to the rarefied gas by means of a saddle antenna through a 13.8 cm ID pyrex tube, similar to the Chi-Kung device at ANU. The source plasma is expanding through a 20 cm ID and 10 cm long port into a .6m and 1.2m long chamber. Two magnetic field coils around the source and one additional downstream coil produce a magnetic field of about 200 G maximum. We have characterized double layers in argon plasmas, and we find that it appears at the position where the plasma expands into the main chamber.
The effect of shaping the magnetic field from an expanding one to a bottle shaped field has also been investigated. In argon, the downstream density and the plasma potential increase significantly as the magnetic field lines are becoming parallel and finally bottle shaped, and the beam from the double layer disappears. We will present also some results from nitrogen.


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Tutelles : CNRS Ecole Polytechnique Sorbonne Université Université Paris Sud Observatoire de Paris Convention : CEA
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Hébergeur : Laboratoire de Physique des Plasmas, Ecole Polytechnique route de Saclay F-91128 PALAISEAU CEDEX
Directeur de la publication : Pascal Chabert (Directeur)