Tokamaks

The sixth Annual Theory and Simulation of Disruptions Workshop at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) made substantial progress toward planning a system for mitigating disruptions on ITER, the international experiment under construction in France to demonstrate the feasibility of fusion power. Disruptions, the sudden loss of heat in plasma that halts fusion reactions, can seriously damage ITER and other doughnut-shaped fusion facilities called tokamaks, and are among the major challenges facing the international experiment. 

Scientists led by Stephen Jardin, principal research physicist and head of the Computational Plasma Physics Group at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), have won 40 million core hours of supercomputer time to simulate plasma disruptions that can halt fusion reactions and damage fusion facilities, so that scientists can learn how to stop them. The PPPL team will apply its findings to ITER, the international tokamak under construction in France to demonstrate the practicality of fusion energy.

Sawtooth swings — up-and-down ripples found in everything from stock prices on Wall Street to ocean waves — occur periodically in the temperature and density of the plasma that fuels fusion reactions in doughnut-shaped facilities called tokamaks. These swings can sometimes combine with other instabilities in the plasma to produce a perfect storm that halts the reactions. However, some plasmas are free of sawtooth gyrations thanks to a mechanism that has long puzzled physicists.