Positronium Molecules Seen in Lab (IMAGE) University of California - Riverside Caption The ultra-high vacuum target chamber, where the intense positron pulse is implanted into the porous silica film. The magnet coils carry a current of 1000 amps for a few hundred milliseconds to generate the strong magnetic field needed to compress the positron beam. Credit David Cassidy, UC-Riverside. 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.