Blinded By the Light

Physicists take an important step toward limitless clean energy, but the payoff won't come for decades

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As the clock crept toward 11:15 p.m. last Thursday, the 500 scientists and engineers packed into the control room and an adjacent auditorium at the Princeton Plasma Physics Laboratory kept their eyes riveted on a bank of computer monitors. They waited anxiously as technicians injected less than 1 oz. of tritium gas into the doughnut-shaped hollow at the heart of a 50-ft.- tall reactor in the next room. Then they waited some more as the tritium mixed with deuterium gas already inside and the combination was heated with powerful radio beams.

The temperature climbed above 100 million degrees -- three times hotter than the core of the sun -- causing the mixture to ignite suddenly in a nuclear- fusion reaction, the same kind that takes place inside stars and hydrogen bombs. More than 3 million watts of energy began pouring from the superheated gas inside the Tokamak Fusion Test Reactor, and for the four seconds or so that the experiment lasted, the hottest spot in the solar system by a sizable margin was in Plainsboro, New Jersey.

As the computers flashed confirmation of the power output, the onlookers erupted in cheers, and not a few tears. Some of them had worked on the project for more than 20 years, and the success of the experiment last week proved that the time had not been wasted. Not only had the researchers trounced the 1.7 million-watt record set by a similar European reactor early last year, they had also taken a major step toward exploiting a safe, clean source of power that uses fuels extracted from ordinary water.

That doesn't mean, however, that anyone should rush to invest in fusion futures. Impressive as Tokamak's achievement was, the $1.6 billion machine generated only one-eighth as much power as it consumed. The next day the reactor managed to generate more than 5 million watts. But even its eventual goal of 10 million will still be only half of the incoming energy. The experiment is an important milestone, but fusion power is still a long way from being commercially useful.

When scientists began working on fusion half a century ago, they had no idea the process would be so hard. It had been relatively easy to get energy through nuclear fission, the breaking apart of such heavy atoms as uranium. That led to A-bombs and today's nuclear power plants. But fusion -- the forcing together of light atomic nuclei, like those of hydrogen -- can release even more energy. The problem is that hydrogen nuclei carry a positive electric charge, and thus they repel one another; they have to be slammed together with terrific force before they will stick. In an H-bomb, that force is provided by a powerful explosive -- an A-bomb, in fact. Inside the sun and other stars, it is a combination of high temperature, which makes the nuclei bounce around with enormous energy, and pressure, which keeps them from bouncing away entirely.

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