Tokamak Plasma (IMAGE) American Physical Society Caption This is an artist's rendering of a tokamak plasma. The plasma is confined by the combination of strong magnetic field in the toroidal direction (around the hole in the "donut" as shown by the black arrow) generated by external coils (not shown) and the magnetic field from a large current flowing in the same toroidal direction. The plasma is held inside a sealed metal structure that is evacuated and lined with special material to keep the plasma pure and handle the heat exhaust. Credit M.R. Wade, General Atomics Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.