Investigation of E x B transport with a multi-electrode probe in the plasma boundary of TEXTOR : First results
A movable multi-element Langmuir probe was implemented in TEXTOR in order to study properties of the edge and scrape-off plasma. The probe has five graphite electrode pins allowing the simultaneous measurement of main plasma parameters such as plasma densities, electron temperatures, floating potentials, poloidal and radial electric fields. Both time-averaged and fluctuating quantities have been considered in order to evaluate the DC and turbulence-driven cross-field particle fluxes. The spectral analysis of the fluctuating floating potentials at spatially separated probe pins allows the determination of the velocity associated with the rotations of the boundary plasma. The investigations have been focussed on the variations of plasma boundary properties in plasmas with pure ohmic heating as well as auxiliary heating (ICRH). Special attention has been paid to the change of transport properties with the transition to a detached plasma. In particular, a significant reduction of the poloidal phase velocity at the limiter edge has been observed for detached plasmas. Preliminary data on physical effects near the plasma boundary, which occur when the toroidal belt limiter (ALT-II) is biased, are reported.
Bibliographic Reference: Report: Jül-2432 EN (1991) 50 pp.
Availability: Available from Zentralbibliothek der Kernforschungsanlage Jülich GmbH, Postfach 1913, 5170 Jülich (DE)
Record Number: 199110896 / Last updated on: 1994-12-02
Original language: en
Available languages: en