Novel advanced Gundestrup-like probe for the measurements of flows and edge plasma parameters in TEXTOR

Abstract

A novel advanced Gundestrup-like probe head for local measurements of equilibrium and fluctuating plasma parameters in the plasma edge of TEXTOR is described. This probe assembly enables us to simultaneously determine the toroidal and poloidal plasma flows, the ion saturation current, density, electron temperature, floating potential, as well as their fluctuating properties. An improved analytical probe model is used to correctly relate the ratio of the ion saturation currents measured at the upstream and downstream collecting surfaces to the plasma flow. The probe is mounted on a fast reciprocating manipulator resulting in a high radial resolution of the profiles. A unique feature of the fast probe is the electrical linear motor drive which allows predefining any wave form of the radial position. The high speed of the probe drive reduces the exposure time which enables us to measure several radial profiles within a single discharge deep inside the last closed flux surface. We describe the first experimental results of flow, radial electric field, ion density, and temperature profiles measured in the plasma edge of TEXTOR. In order to verify the accuracy of these measured quantities we compare the measured radial electric field with the one calculated from the single ion momentum balance equation.