Relaxation of potential, flows, and density in the edge plasma of CASTOR tokamak

Martin Hron, V. Weinzettl, E. Dufkova, C. Hidalgo, I. Duran, J. Stoeckel

Published 2004-10-22Version 1

Decay times of plasma flows and plasma profiles have been measured after a sudden biasing switch-off in experiments on the CASTOR tokamak. A biased electrode has been used to polarize the edge plasma. The edge plasma potential and flows have been characterized by means of Langmuir and Mach probes, the radiation was measured using an array of bolometers. Potential profiles and poloidal flows can be well fitted by an exponential decay time in the range of 10 - 30 microseconds when the electrode biasing is turn off in the CASTOR tokamak. The radiation shows a slower time scale (about 1 ms), which is linked to the evolution in the plasma density and paticle confinement.