In their elegant laboratories near La Jolla, Calif., General Dynamics scientists are doggedly attacking a difficult problem: how to extract controlled power from hydrogen fusion. The pay off for their work is hidden in the future, but the powerful magnetic fields they have built to hold reacting hydrogen gas at 100 million degrees has already yielded a valuable practical “fallout.” Those same magnetic forces used on a smaller scale have proved remarkably versatile for shaping metal.Swift Action.