Determination of velocity shears in a simple magnetized torus by means of a combined Langmuir and Mach probe

We present a multiple electric probe setup for diagnostics of plasmas which is aimed to simultaneously measure the fluctuations of the ion velocity field along one direction and the (ExB) flux perpendicular to it. The probe design is based on combining a Mach probe with two slightly spatially separated Langmuir probes. The probe has been prepared to operate in the turbulent regime of the simple magnetized torus Blaamann. Experiments have been focused on the measurements of shear in the velocity along the magnetic field and on its correlation with the radial flux. Preliminary results are showing the effectiveness of the proposed diagnostics as well as the relevance of velocity fluctuations and correlations in plasma turbulence and in anomalous transport. (C) 2004 American Institute of Physics.