THE glitzy cold-fusion claims this past year have obscured a more substantial story. Research into good old-fashioned hot fusion - the kind that powers the sun and stars - has achieved breakeven. That's the condition where an experimental reactor produces as much power as it consumes. Some laboratories have also demonstrated temperatures (around 100 million degrees) and containment of the star-hot gases that are adequate for practical reactors.
Reviewing fusion research last September, Derek Robinson of Britain's Cullham Laboratory said, ``We are confident that substantial thermonuclear power, comparable with or in excess of the power input, is expected to be obtained in the near future.'' The Tokamak Fusion Test Reactor at the Princeton (University) Plasma Physics Laboratory in New Jersey had achieved 50 percent of breakeven. A few weeks later, Paul-Henri Rebut reported that his Joint European Torus (JET) international team had reached 70 to 80 percent of breakeven. It was an achievement that he considered, for all practical purposes, to represent breakeven conditions.
``The JET project has now basically achieved its principal objective of establishing the scientific feasibilty of nuclear fusion as an energy source,'' Dr. Rebut said.
Thus, with little fanfare, traditional controlled-fusion research has reached a stage toward which it has been striving for nearly four decades. Researchers now look to the next generation of machines to reach the second major stage: ignition of self-sustained fusion reactions. But they need better support than they've been getting to push ahead efficiently.
There are good grounds for cautious optimism for the long-term outlook for fusion power. Yet pessimists also have grounds for skepticism. Dr. Robinson reflected his profession's consensus when he said commercially useful fusion ``will take at least another generation.'' The promised payoff remains where it has been for four decades - a tantalizing 20 years or more in the future.
Support of fusion research today is largely an act of faith. This has led to hesitant funding that slows research, as United States experience illustrates.
The research follows two basic lines. In magnetic fusion - the kind discussed so far - powerful magnetic fields confine the super-heated gases. In the other scheme, laser pulses compress hydrogen fuel pellets to induce fusion. Magnetic fusion is open, peaceful research with much international cooperation. Laser fusion is largely secret and tied to nuclear weapons. Its first payoff is likely to be in weapons research, with civil power applications a longer way off.
Skimpy funding has retarded both research lines in the United States. A decade ago, Congress authorized a program to learn more about the engineering aspects - as well as scientific aspects - of magnetic fusion. Magnetic fusion once got about $500 million a year. Funding slipped to $320.2 million for fiscal 1990. A National Academy of Sciences committee, in an interim report of its review of laser fusion, noted that recommended funding levels were not met in that field either. This year's $169.2 million is $20 million short, with a consequent slowing of research.
An Energy Department panel is studying the situation. It will recommend a new research strategy later this year. It already seems obvious, however, that reliable long-term funding is essential if we are to make the most of present achievements.