TIME: Almanac 1995

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<text id=93TT2236> <title> Dec. 20, 1993: Blinded By The Light </title> <history> TIME--The Weekly Newsmagazine--1993 Dec. 20, 1993 Enough! The War Over Handguns </history> <article> <source>Time Magazine</source> <hdr> SCIENCE, Page 54 Blinded By The Light </hdr> <body> Physicists take an important step toward limitless clean energy, but the payoff won't come for decades By Michael D. Lemonick 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. A-bomb blasts are hardly practical in power plants, and the sun's internal pressure is impossible to duplicate on earth. So fusion scientists put their nuclei in a bottle--not a physical one, since any contact with the walls would instantly cool the gas and kill the reaction--but a bottle made of magnetic fields. The researchers would make up for the comparatively low pressure inside by raising the temperature to unheard-of levels. (A competing idea that shows promise uses converging laser beams to compress and ignite a stream of tiny, gas-filled glass pellets.) Confining a gas made of electrically charged atomic nuclei--a plasma--has proved to be far more complex than anyone had suspected, and so has heating it. While the first rudimentary fusion reactors were a few feet across and weighed a ton or two, the Tokamak weighs hundreds of tons and fills a gymnasium-size room. A commercial reactor would be much bigger still and with current technology would cost hundreds of billions of dollars. The main attraction of fusion is the potentially limitless fuel supply. The ideal fuel is not plain hydrogen but the formula used last week: a mixture of deuterium and tritium, two isotopes of hydrogen that have extra neutrons in their nuclei. Even though they're rarer than ordinary hydrogen, scientists estimate that enough of these two isotopes could be extracted from the top 2 in. of water in Lake Erie to match the energy in all the world's oil reserves. But no one knows for sure whether fusion on a large scale will be practical. The U.S. Department of Energy has canceled a bigger machine that was supposed to go beyond what Tokamak can achieve. Instead America will join the Europeans, Japanese and Russians in building the International Thermonuclear Experimental Reactor; when it goes into operation a decade or so from now, fusion scientists should finally have a device that generates more power than it consumes. Even then it will take decades of engineering before any households could possibly draw electricity from a commercial fusion plant. </body> </article> </text>