After nearly a half-century of effort and many billions of dollars, scientists for the first time have produced a significant amount of power from controlled nuclear fusion.
The achievement is a major step in harnessing for constructive use the kind of thermonuclear fire that lights the sun and produces the awesome blast of the hydrogen bomb.
The advance was made Saturday by researchers at the Joint European Torus, or Jet, at an experimental fusion reactor in Oxfordshire, England. The achievement puts the European team ahead of Soviet, Japanese and U.S. rivals.
The Europeans' gain was particularly painful for U.S. researchers since they first began to look at the idea of controlling nuclear fusion almost 50 years ago and had hoped to reach this milestone first.
The goal of the research is to fashion machines that will produce a new kind of nuclear energy that is cheap, clean and virtually inexhaustible. If feasible, that goal might take as much as another half-century of hard work to achieve.
A major attraction is that the main fusion fuel, deuterium, a heavy form of hydrogen, can be easily extracted from water in nearly endless quantities. In theory, fusion could produce far more energy from the top two inches of, say, Lake Erie than exists in the earth's oil reserves.
The Jet advance is considered significant because it marks the first time that the principles of the research have been tested and resulted in high power.
"This is the first time that a significant amount of power has been obtained from controlled nuclear fusion reactions," Dr. Paul-Henri Rebut, director of Jet, said in a statement. "It is clearly a major step forward in the development of fusion as a new source of energy."
In an interview yesterday, Dr. Ronald C. Davidson, director of the Princeton Plasma Physics Laboratory in New Jersey, one of Jet's main rivals, agreed with that assessment. "This is a historic event," he said.
The closest natural example of fusion is the sun, where temperatures at the core are 14 million degrees Centigrade and gravitational pressures are crushing. There, atomic nuclei are driven so close together that they fuse and release energy.
Up to now, fusion reactors have at best produced thousands of watts of power in short bursts. But at Jet, for the first time, scientists produced more than a million watts of power. The Jet team calculated that its reactor yielded 1.5 million to 2 million watts in a pulse lasting two seconds.
"The Jet work marks the beginning of the actual use of fusion fuel," said Dr. Stephen O. Dean, president of Fusion Power Associates in Gaithersburg, a non-profit group that promotes fusion research.
The Jet achievement, Dr. Dean added, still falls short of break-even, the point where the energy released by a fusion reaction matches that put into a machine to induce fusion.