Direct observation of a cross-field current-carrying plasma rotating around an unstable magnetized plasma column

The low-frequency instability of a magnetized plasma column and the existence of a rotating peripheral plasma are shown to be correlated with a radial cross-field electron current. The direct observation of the rotating plasma is obtained using an ultrafast intensified camera. The ionizing electrons injected along the axis of the plasma column contribute to the accumulation of negative charges when the axial collector is at floating potential. The required neutrality leads to the continuous radial expulsion of both energetic and thermal electrons and to the formation of a rotating plasma channel.