An alternative approach to achieving nuclear fusion in the laboratory
LIKE conquistadors seeking El Dorado, physicists cannot leave the idea of fusion power alone. Some spend billions of dollars of taxpayers’ money on the huge machines they believe are the best way to generate the temperatures and pressures needed to persuade atomic nuclei to merge with one another. Others still think there is something to the idea of “cold” fusion, and tinker hopefully with desktop apparatus full of electrodes made from exotic metals and electrolytes containing obscure isotopes of hydrogen.
Eric Lerner, however, believes there is a third way. His experimental device does not quite fit on a desktop (its sides are a couple of metres long) but nor does it cost billions (a few hundred thousand is closer to the mark). Nor, in truth, does it do fusion yet. But on October 20th he announced it had reached what might be seen as base camp on the climb to that goal.
Mr Lerner’s machine is called a dense plasma focus fusion device. It works by storing charge in capacitors and then discharging the accumulated electricity rapidly through electrodes bathed in a gas held at low pressure. The electrodes are arranged as a central positively charged anode surrounded by smaller negatively charged cathodes.
When the capacitors are discharged, electrons flow through the gas, knocking the electrons away from the atomic nuclei and thus transforming it into a plasma. By compressing this plasma using electromagnetic forces, Mr Lerner and his colleagues at Lawrenceville Plasma Physics, in New Jersey (the firm he started in order to pursue this research) have created a plasmoid. This is a tiny bubble of plasma that might be made so hot that it could initiate certain sorts of fusion. The nuclei in the plasmoid, so the theory goes, would be moving so fast that when they hit each other they would overcome their mutual electrostatic repulsion and merge. If, of course, they were the right type of nuclei.