Study of spatio-temporal intermittency regime around a magnetized plasma column

M. Matsukuma, Th. Pierre, A. Escarguel, G. Leclert, D.Guyomarc'h
Lab. PIIM, University of Marseille, France

F. Brochard, E. Gravier, G. Bonhomme
Lab. PMIA, Université Henri Poincaré, France

In order to study radial transport around a magnetized plasma column, a diaphragm has been put at the entrance of the MISTRAL and MIRABELLE devices to reduce the diameter of the column. When regular regimes are obtained in the column, a conditional sampling method shows a spiral arm structure in the area behind the delimiter. A linear study, based on the drift of particles induced by the density gradient, radial electric field and centrifugal force, is in good agreement with the recorded structures. Moreover, numerical simulations underline the importance of ion collisions in the apparition of spiral structures. Intermittency of the density is observed behind the delimiter for spatio-temporal chaos regimes.