On the Way: Genuine Fusion

Scientists who strive toward achieving thermonuclear power--the controlled fusion of hydrogen--have fooled themselves so many times that they are reluctant to claim success. But last week in Washington, Dr. James L. Tuck of Los Alamos Scientific Laboratory told the Joint Congressional Committee on Atomic Energy: "We are now prepared to stake our reputations that we have a thermonuclear reaction."

Many scientists in many laboratories have squeezed hot deuterium (heavy hydrogen) between powerful magnetic fields and got short bursts of neutrons which made them think that the deuterium was turning into helium and giving off hits of H-bomb energy. This would be something to cheer about. It could lead to a fusion power plant that would i) create little radioactivity; and 2) burn comparatively cheap deuterium, which is plentiful enough in all water to give each gallon the energy yield of 300 gallons of gasoline. But the scientists usually found that the neutrons came from less interesting reactions--and never could they prove that they came from genuine fusion.

Egg-Shaped Fireball. The success cautiously announced by Dr. Tuck was achieved by Scylla, a cylindrical chamber about 30 inches long in which deuterium is squeezed by a sudden magnetic shock. The squeeze produces an egg-shaped fireball about 0.8 in. long containing five times 1016 (50 million billion) deuterium nuclei at a temperature of 13,000,000DEGC. It lasts about 0.9 millionth of a second, and spits out about io million neutrons.

Dr. Tuck is sure that the Scylla neutrons came from genuine fusion of deuterium, but he points out that Scylla was never intended to be a practical source of thermonuclear energy. More promising for this purpose is Picket Fence, an apparatus that forms a cavity between strong magnetic fields. When deuterium nuclei are shot into the cavity, they sometimes stay there for 30 millionths of a second, a very long time in thermonuclear physics. Said Dr. Tuck: "For the first time I see in this device faint glimmerings of a possibility of making a thermonuclear reactor."

Smog Chaser. Also before the Joint Atomic Energy Committee, Dr. David B. Hall of Los Alamos took down his scientific hair and discussed some of the jobs that may open for nuclear reactors in the foreseeable future. Reactors are very good, he said, at generating low-cost heat, and the time may come when the world needs to conserve its remaining liquid fuel to run land and air vehicles. Then reactors can take over the job of supplying process heat (e.g., for industrial use) and space heat (e.g., for homes), which account for half the energy consumed in the U.S.

Some scientists suspect that the ever-increasing amount of fossil fuel that is burned may be increasing the amount of carbon dioxide in the atmosphere. They fear that the added CO-will have a "greenhouse effect," trapping solar heat at the earth's surface and raising its temperature. The result may be unpleasant changes of climate, including deserts in many places that are now fertile, and a disastrous rise of sea level because of melting icecaps. A cure might be a world agreement to use nuclear reactors wherever possible. They excrete no CO^2

One U.S. city, said Dr. Hall, might make good use right now of a monster reactor. Over Los Angeles a layer of warm air (an inversion) hangs for long periods and traps beneath it the city's notorious smog. Dr. Hall believes that a reactor, operating at comparatively low temperature but generating 100 million kilowatts of heat, could punch a hole in the inversion and clear L.A. of smog.

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