The Pulsator tokamak

Pulsator was operated by IPP Garching from 1973 to 1979. It made two important contributions to international tokamak research. 1. In Pulsator, for the first time a tokamak plasma was influenced locally by an external, resonant, helical field. The accompanying formation of islands on magnetic surfaces, which affects transport and stability, provided the starting point for experimental investigation of the disruptive instability and its theoretical description. 2. By gas puffing during the discharge it was possible to attain a high-density regime which dramatically raised the then prevailing nτ E values by almost two orders of magnitude. In this high-density regime an inward directed particle drift velocity and, as a consequence, under certain conditions an accumulation of impurities in the plasma core was found.