Experts assemble at PPPL to discuss mitigation of tokamak disruptions

Some 35 physicists from around the world gathered at PPPL last week for the second annual Laboratory-led workshop on improving ways to predict and mitigate disruptions in tokamaks. Avoiding or mitigating such disruptions, which occur when heat or electric current are suddenly reduced during fusion experiments, will be crucial for ITER the international experiment under construction in France to demonstrate the feasibility of fusion power.

Presentations at the three-day session, titled “Theory and Simulation of Disruptions Workshop,” focused on the development of models that can be validated by experiment. “This is a really urgent task for ITER,” said Amitava Bhattacharjee, who heads the PPPL Theory Department and organized the workshop. The United States is responsible for designing disruption-mitigation systems for ITER, he noted, and faces a deadline of 2017.

Speakers at the workshop included theorists and experimentalists from the ITER Organization, PPPL, General Atomics and several U.S. Universities, and from fusion facilities in the United Kingdom, China, Italy and India. Topics ranged from coping with the currents and forces that strike tokamak walls to suppressing runaway electrons that can be unleashed during experiments.

Bringing together theorists and experimentalists is essential for developing solutions to disruptions, Bhattacharjee said. “I already see that major fusion facilities in the United States, as well as international tokamaks, are embarking on experiments that are ideal validation tools for theory and simulation,” he said. “And it is very important that theory  and simulation ideas that can be validated with experimental results are presented and discussed in detail in focused workshops such as this one.”