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Accueil du site > Évènements > Séminaires > Séminaires IRPHE > Archives IRPHE > 2015

Vendredi 12 Juin / IRPHE

publié le , mis à jour le

Séminaire régulier IRPHE

Toward a von-Kàrmàn plasma experiment

Orateur : Nicolas Plihon
Laboratoire de Physique de l’ENS Lyon

Résumé :We will present our project of a von-Kàrmàn plasma experiment in which a low pressure, high density plasma is set into motion in a slightly magnetized linear configuration. The plasma flow is driven by the Lorentz force provided by the interaction of the confining (axial) magnetic field with radial currents driven by emissive cathodes - in a way similar to the scheme proposed by the group of C. Forest [1]. In the mid-term views, each end of the plasma column will be counter-rotating, such as to create a large shear-layer, resulting in a von-Kàrmàn-type flow. These von-Kàrmàn flows have been widely used in liquid metals for magnetic induction studies and demonstrated their ability to trigger the dynamo instability [2]. We will discuss in more details on the first phase of the project, in which one single cell of the setup is investigated (i.e. the plasma is set into motion from one single side of the cylinder) [3]. Flows up to 1 km/s have been measured with electrostatic Mach probes and non intrusive Laser Induced Fluorescence. More recently, instabilities driven by plasma pressure gradients have been characterized using high-speed imaging. The experimental investigations are supported by numerical simulations in the MHD framework, with the implementation of (immersed-boundary) penalization method in order to accuretly describe the experimental boundary conditions.
[1] Collins et al., Phys. Rev. Lett., 108, 115001 (2012)
[2] Verhille et al., Space Sci Rev., 152, 543–564 (2010)
[3] Plihon et al., J. Plasma Phys., 81, 345810102 (2015)

Date et lieu : le Vandredi 12 Juin 2015 à 11h00, salle de séminaire IRPHE