Superconducting coils (IMAGE) Lehigh University Caption The largest poloidal-field coils needed for ITER are manufactured by European partners in this 250-meter-long on-site production facility. These superconducting coils, ranging in diameter from 17 to 24 meters and weighing 200 to 400 tonnes, are simply too big to be manufactured off site and shipped to ITER. The poloidal-field coils are used in tokamaks mainly to stabilize and shape the plasma inside the vacuum vessel. Credit Courtesy of Eugenio Schuster Usage Restrictions Contextual, credited use only License Original 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.