A simple device that fits into a lab-coat pocket can be used to achieve deuterium-deuterium fusion along with its associated neutron flux under desktop conditions, according to scientists at the University of California, Los Angeles (Nature 2005, 434, 1115).
The device is not practical for power generation, but it may find use as a palm-sized neutron generator in the laboratory.
Unlike magnetic and inertial confinement fusion, the new UCLA system is a tabletop method for producing nuclear fusion, but it's otherwise not related to the "cold fusion" and "bubble fusion" claims of recent years that have met with deep skepticism. The physics behind it is conventional and accepted, says lead author Brian Naranjo, of physicist Seth J. Putterman's group, which is collaborating with chemist James K. Gimzewski.
The apparatus they used consists of a chamber containing a lithium tantalate (LiTaO3) crystal and an erbium deuteride (ErD2) target in a low-pressure atmosphere of deuterium. When the crystal is gently warmed, it generates an electric field that is concentrated at the tip of a tungsten needle attached to the crystal. At the tip, the D2 molecules become ionized and the D+ ions are accelerated toward the ErD2 target, where D + D fusion occurs, producing helium-3 and a 2.45-MeV neutron, a signature of D + D fusion. About 900 neutrons per second are produced--400 times the usual background level.
By enhancing the system and using a tritiated target, the researchers expect to boost the flux beyond 1 million neutrons per second.
Even at the flux already attained, a simple, inexpensive, single-energy neutron source like this one would be desirable for lab applications such as measuring the response of neutron detectors or for student demonstrations, notes physicist Michael J. Saltmarsh of Oak Ridge National Laboratory.