Sawtooth oscillations of various plasma parameters in correlation to periodic changes of the internal magnetic field structure
In order to obtain detailed information on plasma profile changes during regular sawtooth activity in ohmic discharges on TEXTOR, the resolution of various diagnostic systems has been increased substantially with respect to both their signal to noise ratios and their spatial resolution. The diagnostics involved are: - a combined far-infrared polari-interferometer to determine electron density and magnetic field distributions; - an ECE system to measure electron temperature profiles, and - two soft X-ray cameras to observe a poloidal plasma cross-section from the top of the vacuum vessel along 40 lines of sight. By making use of the high reproducibility of the sawtooth phenomenon under appropriate plasma conditions, coherent signal averaging techniques have been applied to merge many individual sawteeth into one representative sawtooth with low noise. The time resolution of the diagnostic systems ranges from 100 micro-seconds for the soft X-ray cameras to 1 ms for the polarimeter. This is sufficient to follow the evolution of the respective plasma parameters throughout a sawtooth cycle. Details of the rapid crash phase are, however, not resolved.
Bibliographic Reference: Article: 18th European Conference on Controlled Fusion and Plasma Physics, Vol. II (1991) pp. 17-19
Record Number: 199111385 / Last updated on: 1994-12-02
Original language: en
Available languages: en