Tokamaks are donut-shaped reactors that are among the most widely used devices in the effort to achieve fusion energy — the same energy that powers the sun and stars. But their use is hampered by the potential of violent disruptions to occur inside tokamaks during the fusion process.

Now, researchers are seeking to mitigate these disruptions and the damage they cause using a device called an “electromagnetic particle injector.”

Disruptions occur when plasma — ultra-hot, gas-like matter — inside the tokamak becomes unstable, leading large electromagnetic forces and thermal loads to slam against the vessel’s walls and potentially damage the tokamak’s components.

As outlined in a recent paper in Nuclear Fusion, the new injectors are designed to mitigate the problem by firing a high-speed projectile of material that will radiate away the energy in the core of the plasma at the first sign of disruption.

Researchers at the U.S. Department of Energy’s Princeton Plasma Physics Laboratory have built and successfully simulated the prototype of this device. Plans now call for testing the injector, and it is hoped that these devices will be in place in 2025 when ITER, the international fusion experiment, fires up.