Current measurements in the scrape-off layer of Tore Supra with the new CIEL limiter

The current flowing between the new toroidal pump limiter of Tore Supra and the inner wall components was investigated. The response of the current to a change of the wall clearance as well as to a variation of the poloidal and toroidal magnetic field was studied. A simple estimate of the thermoelectric currents resulting from the radial temperature gradient is presented. We find, that the dependance of the measured current on the wall clearance can be reproduced by prescribing a deviation of the plasma potential from the sheath potential. (C) 2003 Elsevier Science B.V. All rights reserved.