Pyrofusion

Pyrofusion. A room-temperature, palm-sized neutron generator that uses nuclear fusion has been reported by UCLA scientists. The key component is a pyroelectric crystal that, when heated, becomes charged on a surface. The researchers attached a tungsten probe to a copper disc mounted on the crystal and put the whole arrangement in a vacuum chamber containing deuterium gas. When the crystal is heated, a strong 25-V/nm electric field is generated at the end of the tungsten tip; any nearby deuterium atoms have their electrons stripped away. Repelled by the positively charged tip in the electric field, the resulting deuterium ions then accelerate toward a solid target of erbium deuteride and slam into it so hard that some of the deuterium ions fuse with deuterium in the target. Each D–D fusion reaction creates a helium-3 nucleus and a 2.45-MeV neutron. In a typical heating cycle lasting several minutes, the researchers measured a peak of about 800 neutrons per second—400 times the background of naturally occurring neutrons. The researchers think they can scale up the observed production to more than 10⁶ neutrons per second by using a larger tungsten tip, operating at cryogenic temperatures, and constructing a target containing tritium. (B. Naranjo, J. K. Gimzewski, S. Putterman, Nature 434, 1115, 2005).