Geneva summit fuels hopes for tapping fire of the stars. Statement on fusion energy holds promise for joint effort

It's only one sentence among thousands settled on by American and Soviet negotiators in the joint statement at last week's Geneva summit. But the single, vaguely worded reference to US-Soviet cooperation on thermonuclear fusion research -- which promises a virtually inexhaustible energy supply -- has grabbed the attention of the American scientific community.

Thermonuclear fusion is the same type of atomic reaction that drives the sun's furnace and endows the hydrogen bomb with its vast destructiveness. Unlike fission, the nucleus-splitting reaction at the heart of atomic power plants, fusion is the act of combining atomic nuclei, which also releases vast amounts of energy. The ability to harness this fire of the stars as a safe, clean, and nearly unlimited source of energy is still a drawing-board fantasy for researchers around the globe. But its promise ap pears realistic enough to have mobilized major research efforts in Europe, Japan, the Soviet Union, and the United States.

The reference in the statement signed by President Reagan and Soviet leader Mikhail Gorbachev holds the promise for increased cooperation between the two countries on fusion research. Such research has been conducted jointly by the two nations since President Nixon and Soviet Premier Leonid Brezhnev signed an agreement on cooperation in atomic-energy research in 1973.

Joint efforts, however, have been sharply curtailed since the 1970s: At one point many of the agreements providing for scientific exchanges between the two countries were allowed to lapse, and Congress seriously considered a measure that would have halted the exchange of any technical material with the Soviets.

Yet government sources said last week's statement could mean that a major upgrade in the scope of fusion research projects undertaken by the two countries is in the offing; possibly by the next time the 1973 accord is up for its next review in 1988.

For some American researchers, that would not be a moment too soon. The US fusion effort is still the most extensive in the world, partly because of a 1980 law passed by Congress just after the 1979 oil crisis that doubled federal support for fusion research. But in the not-too-distant future, US research will begin to assume more modest proportions.

Fusion has fallen out of fashion of late. A number of greatly anticipated advances did not materialize. Doubts grew about the feasibility of fusion power among congressional budget specialists just as fossil-fuel prices plummeted.

The federal government -- the major source of money for fusion research -- has cut its support dramatically over the past few years. From a peak of $483 million in 1984, the federal allotment for fusion research has plummeted to $382 million for fiscal 1986. That, in turn, has led researchers to postpone a number of experiments deemed critical to the advance of fusion science.

``You can look at things now and they seem OK,'' says Harold Ferth, a physicist at Princeton University and director of its Plasma Physics Laboratory. ``Come back in five years or so, and you may see a different story.''

Partly for that reason, US scientists are generally receptive to international cooperation -- and financing -- of major scientific projects. Indeed, as scientific endeavors become more colossal and spectacular, so does their price tag. That necessitates international cooperation, and international cooperation is becoming the rule rather than the exception.

For example, plans to build a gigantic, atom-smashing particle accelerator for basic research into the nature of matter may hinge on whether joint US-European financing can be arranged. The National Aeronautics and Space Administration has openly solicited help from Europe and Japan on such projects as the shuttle-riding Spacelab and the future space station.

Scientists here also express confidence that increased cooperation with the Soviets would benefit both sides. While the West is said to hold an edge over the Soviets in the design and construction of equipment necessary to carrying out research, Soviet theoreticians are said to be at least the equal of anyone else's.

In fact, since 1978, scientists from Europe, Japan, the US, and the Soviet Union have been working at the UN International Atomic Energy Agency in Geneva on a design for an experimental test reactor, called a Tokamak, in which a controlled thermonuclear reaction could be sustained.

``The Soviets have produced their fair share of important and new ideas that wouldn't otherwise be available to us,'' says Weston M. Stacy, a professor of nuclear engineering at the Georgia Institute of Technology and leader of the American scientific team in Geneva. ``From what I've seen so far, cooperation has been good for both sides.''