Violently turbulent plasma storms of varied shapes and sizes occurring in current tokamak experiments make it difficult to predict with certainty how any given discharge will behave. High-performance computing will play a profoundly important role in designing these machines. Applications Predictive scaling studies of three-dimensional turbulence in tokamaks such as those represented by this work are important to characterizing and understanding current and proposed experiments. An example of one such issue is how the character of plasma turbulence changes with the size of the tokamak and with the shape of the electrical plasma current. Strong plasma turbulence in tokamaks increases the mixing of the hot dense plasma in the reactor core, where fusion occurs, with the cooler edge plasma near the reactor wall.
Fusion reactors rely on fusion energy released in the core plasma to keep the reaction going.
If the hot dense fuel plasma in the reacting core mixes too quickly with the cooler edge plasma, the fusion reaction is extinguished. The massively parallel computers now becoming available can relax the limits that have constrained computational research in this arena for decades. The red and blue correspond to counterrotating vortex cell cores aligned with the magnetic confinement field. The turbulent flow causes mixing of hot plasma from the tokamak center with cooler plasma from the periphery. In simple terms, the more strongly the plasma is heated, the stronger the turbulence.