George Miley peers in and glimpses a tiny luminescent ball hanging in the centre and spires of light that seem to radiate from it. Miley is professor of nuclear, electrical and computer engineering at the University of Illinois in Urbana-Champaign and his sphere is a fusion machine. The sphere is different in other ways too. It's primary purpose is not make energy but to generate neutrons. Billions of them, every second.
Neutrons are subatomic particles with no electric charge that are extraordinarily useful.
Scientists use them for materials analysis-they can help to identify most common elements in seconds. By contrast, chemical analysis can take hours. Beams of these particles can even be used for cancer treatment. The trouble is that neutrons are notoriously difficult to make. Nothing less than a nuclear reactor or a high powered particle accelerator will do the job.