Newspaper article The Christian Science Monitor

How to Harness the Power of the Stars on a Table Top Scientists Announce That They Can Achieve Fusion on a Small Scale -Aiding Research into a Unique Energy Source

Newspaper article The Christian Science Monitor

How to Harness the Power of the Stars on a Table Top Scientists Announce That They Can Achieve Fusion on a Small Scale -Aiding Research into a Unique Energy Source

Article excerpt

A few years ago, Todd Ditmire's on-the-cheap fusion-energy experiment would have drawn smirks from high-powered research teams that work with lasers big enough to fill large halls.

Now, entering what some are calling a new realm of physics, Dr. Ditmire and his colleagues at the Lawrence Livermore National Laboratory in California, have achieved nuclear fusion - the process that lights the stars - by using a table-top laser to zap tiny puffs of gas.

Their device will never power a Sony Play Station or light up a 60-watt bulb. That's the long-term goal of researchers trying to design and build large-scale fusion reactors that would turn water into steam to generate electricity. Ditmire's approach, however, could accelerate fusion research by reducing the cost to conduct such studies, allowing more scientists to take part, experts say. Moreover, table-top fusion "reactors" eventually could play an important behind-the-scenes role as cheap, environmentally friendly sources of neutrons - subatomic particles that are increasingly valuable tools in looking for oil, maintaining aircraft, and developing new materials for products ranging from pharmaceuticals to pocket calculators. Such reactors "would give you neutrons without fission," says Greg Moses, associate dean for research at the University of Wisconsin's College of Engineering. Fission - splitting atoms' nuclei and tapping the energy released - is the basis for today's nuclear power plants and research reactors. It yields significant amounts of radioactive waste. Fusion energy, by contrast, is released when atomic nuclei slam together with sufficient energy to merge - a relatively clean process. Ditmire explains that his device grew out of work using lasers to probe the properties of matter. For several years, physicists and chemists have been interested in how matter responds to extremely intense, rapid pulses of laser light. When such light hits individual atoms, for example, it strips them of their electrons, turning them into ions. When such lasers are focused on groups of 10 to 10,000 atoms, though, these clusters produce extremely hot, microscopic balls of electrically charged gas, or plasma. The plasma explodes, ejecting ions at energy levels that correspond to temperatures as high as 1 billion degrees Celsius. When Ditmire's team aimed its laser at a jet of gas containing clusters of deuterium, a form of hydrogen, the exploding plasma ejected deuterium ions with sufficient energy to fuse those that collided. The energy level of neutrons emerging from the fused nuclei provided the "smoking gun," establishing the process as a fusion reaction. …

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