An astonishingly simple demonstration of nuclear fusion in a tabletop device has been performed, involving heating an ordinary crystal soaked in deuterium gas. While the technique is unlikely to lead to power generation, such a device could act as a portable source of neutrons for analysing materials and medical imaging, and perhaps even spacecraft propulsion.The key to the system is a crystal made of lithium tantalate. The crystal is asymmetric and, as a result, heating the material causes positive and negative charges to migrate to opposite ends of the crystal, setting up an electric field. The phenomenon is known as the pyroelectric effect.In 1992, James Brownridge at the State University of New York in Binghamton, US, used crystals of lithium tantalate to generate X-rays by heating the crystals to about 100ºC in a dilute gas. The resultant electric field strips electrons from the gas molecules and accelerates them to huge energies. The electrons then collide with stationary nuclei in the crystal and generate X-rays.When Seth Putterman at the University of California, Los Angeles, US, heard of the phenomenon a few years ago, he immediately realised that the electric fields were powerful enough for nuclear fusion to occur, specifically to fuse nuclei of an isotope of hydrogen called deuterium. The fields inside the crystals can reach a “mind boggling” 107 electronvolts, he says.To test whether these fields could indeed cause nuclear fusion, Putterman and UCLA colleagues Brian Naranjo and James Gimzewski first bathed a crystal of lithium tantalate in deuterium gas. The setup was then cooled to -33ºC and then heated to about 7 ºC over three and a half minutes.
View: Full Article | Source: New Scientist