Investigation of the Parameters in the Boundary Plasma of ASDEX by Means of a Langmuir Probe.

摘要

The electron temperature and density were routinely measured at the edge of the ASDEX main plasma by means of a fast moving triple probe which gives the saturation current and Tsub(e) on line. These measurements were made in ohmically heated discharges and during neutral beam injection in order to study the radial dependence of the plasma parameters in the boundary layer and the effects of auxiliary heating on it. During lower hybrid application we observed strong poloidal and toroidal deviations in the floating potential that inhibit the operation of a triple probe. To investigate these effects, we used double probes and floating potential measurements. The most important reason, but not the only one, for these floating potential inhomogeneities are changes in the electron temperature of typically 10-20 eV over a distance of a few milliseconds. (ERA citation 12:010495)