Density fluctuations level during sawtooth relaxations in tokamak plasmas
Specific turbulence (ST) associated with the sawtooth internal disruption has been observed on TFR Tokamak plasmas by analysing density fluctuations with CO(2) laser light scattering. This is compared with Andreoletti's disruption model. ST is defined here as the difference between the "quasi instantaneous" fluctuations and the stationary ones detected any time outside the period surrounding the collapse . From the soft X-ray signals, four phases in the process can be identified. No ST fluctuations are detected during the main regeneration period and the resistive kink phase. No significant deviation between one particular spectrum and an ensemble average of several spectra is detected. Enhanced fluctuations appear for typically 20 microsecs in coincidence with the turbulent kink phase. The main burst of additionary flutuations appears during the collapse phase and lasts about 20 microsecs. This paper essentially deals with an evaluation of the level of fluctuations during this phase. Finally, an intermediate level of ST is observed during the return phase. Its amplitude is comparable to the one observed in the second phase and again it lasts about 20 microsecs.
Bibliographic Reference: Paper presented: International Conference on Plasma Physics, New-Delhi (IN), Nov. 22-28, 1989
Availability: Available from (1) as Paper EN 34996 ORA
Record Number: 198911227 / Last updated on: 1994-12-01
Original language: en
Available languages: en