Specific turbulence associated with sawtooth relaxation in TFR plasmas
A CO(2) coherent scattering diagnostic is used to examine a specific turbulence during the sawtooth relaxation which is superimposed on the quasi-stationary (QS) turbulence. The scattering volume consists of a vertical chord which is radially scanned. The presently reported experiments, performed on TFR Tokamak, concern k = 5 or 7 /cm. A careful analysis of the temporal amplitude variation defines three stages in the turbulent process in agreement with the soft X-Ray signals. Each stage typically lasts 20 microsec. The first stage is associated with a displacement of the hot core. The increase of fluctuations amplitude is clear but modest. The second stage coincides with the main crash of the emissivity signal. Its amplitude is large. Finally, a third stage coincides with the reorganisation process during which the central region of the plasma recovers its symmetry. During this phase, the amplitude and spectrum of the turbulence are comparable with the ones of the first phase. The reported data are uniquely concerned with the second phase and are focussed on the spatial localisation of the specific turbulence.
Bibliographic Reference: Paper presented: 16th European Conference on Controlled Fusion and Plasma Physics, Venezia (IT), March 13-17, 1989
Availability: Available from (1) as Paper EN 34464 ORA
Record Number: 198910803 / Last updated on: 1994-12-01
Original language: en
Available languages: en