EVOLUTION OF RADIATION POWER PROFILES IN ASDEX H-MODE DISCHARGES
The paper compares radiation power profiles, energy exhaust and impurity radiation mechanisms of the two types of H mode during neutral injection heated divertor discharges in the tokamak ASDEX. The normal H-mode discharge that reaches a quasi-stationary state is characterized by moderate radiation power losses of the main plasma and by repetitive burst-like energy release from its outer half radius zone into the divertor. In contrast, the burst free variant of the H-mode shows superior energy and particle transport properties but becomes dominated by radiation power losses growing continuously up to 100% of the heating power input. The dynamic behaviour, i.e. the variation in time, of the iron concentration and the associated radiation power density at the plasma centre is hardly influenced by the kind of H-mode. But, if the concentration of metals with medium Z-value is raised to sufficiently high values in the burst dominated H-mode plasma, e.g. by the accumulation of intrinsic iron, the burst free (or burst deficient) H-mode is triggered, which after a new accumulation period usually ends by a radiation collapse.
Bibliographic Reference: WRITE TO MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, 8046 GARCHING BEI MUENCHEN (GERMANY), MENTIONING REPORT IPP III/112, 1986
Record Number: 1989124136500 / Last updated on: 1987-01-01
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