General Physics Seminar Thursday 14 March 2002


The Dynamic Ergodic Divertor on TEXTOR

Karl_Heinz Finken

Institut fuer Plasmaphysik, Forschungszentrum Juelich
Juelich, Germany



TEXTOR is presently open for the installation of the Dynamic Ergodic Divertor, DED. According to the latest planning, the machine will go into operation in August 2002.
The perturbation currents of the DED flow in 16 coils which are located at the high field side inside the TEXTOR vessel. These perturbation currents create resonances in the plasma edge between 2 < q(r) < 4; if the perturbation is strong enough, the magnetic field lines become interwoven in this volume which is called ergodization. Aim of the ergodization is a spreading of the heat flux to the walls to a large area.

In contrast to other ergodic divertors, the one of TEXTOR has the unique feature to be dynamic; this means that the perturbation field is not static but can also rotate. Different rotation frequencies are foreseen from a few Hertz up to 10 kHz. This rotation helps on one hand the spreading of the power flux (low frequency operation), on the other hand it also transfers a force from the DED coils to the plasma. A substantial (differential) rotation of the edge plasma is expected.
The DED programme will allow the study of these and additional effects.