Halo currents in a circular Tokamak: measurements on Tore Supra

At Tore-Supra, the plasma position, the magnetic axis, the density and the current profiles are calculated in real time, using data from magnetic probes, infrared interferometry and polarimetry. Measurement and calculations are performed by several VME microcomputers and the data are shared in a common memory (SCRAMNet bus). The infrared interfero-polarimeter has been upgraded to self-calibrate for a few seconds before each discharges. This provides more accurate data needed for the determination of the current profile shape. New powerful algorithms are used to compute profile shapes, and several control parameters are tested in order to feedback on LHCD power and/or the wave number spectrum. (authors)