Tomographic investigation of internal disruptions in the ASDEX and TFTR tokamaks
Sawtooth instability greatly impairs the reactivity of the plasma. This work is a study of the structure of flux surfaces in the sawtooth collapse phase during discharges which are strongly heated by neutral injection. Soft X-rays in a poloidal plane in ASDEX were measured with 10 micro-seconds resolution, and the line integrals of the radiation were tomographically inverted in order to determine the radiation profiles. To improve on the resolution which was obtained by using existing methods, a new tomographic process, based on the Cormack method, was developed. It was possible to demonstrate that the sawtooth collapse in ASDEX and TFTR accords with the Kadomtsev model of resistive reconnection of the helical flux. The type of sawtooth shape appearing is greatly dependent on the discharge conditions under which it occurs. Nevertheless, with the help of tomography it was shown that the factor common to all the internal disruptions investigated is the reconnection of the helical flux.
Bibliographic Reference: Report: IPP III/175 DE (1991) 112 pp.
Availability: Available from Max-Planck-Institut für Plasmaphysik, 8046 Garching bei München (DE)
Record Number: 199110893 / Last updated on: 1994-12-02
Original language: de
Available languages: de