Field lines and magnetic topology in a SPI simulation for JET

The picture shows field lines originating from the frozen shards in the early phase of a shattered pellet injection (SPI) simulation for JET. The color of field lines corresponds to the density of the ablated material. The radiation cooling from the ablated impurities induces MHD activity resulting in the formation of a 3/1 magnetic island as shown with the white dots (Poincaré plots). The induced MHD activity will eventually make the magnetic field fully stochastic and this will trigger a collapse of the plasma temperature (so-called thermal quench). In this early simulation phase most of the flux surfaces are still nested tori and the resulting temperature (as shown with color contours in the two poloidal cross-sections) is high in the core. SPI is one of the most promising techniques to mitigate thermal and electromagnetic loads from disruptions in fusion plasmas. (c) Daniele Bonfiglio & JOREK Team.