Science: Toward Controlled Fusion

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Controlled hydrogen fusion−the key to cheap, abundant energy−is still miles away but it is getting closer. After a two-day conference at Princeton, N.J. last week, U.S. and British atomic officials made the guarded announcement that several different approaches to the fusion problem have "for some months been yielding substantial numbers of neutrons . . ." These neutrons, the announcement explained, may come from the energy-yielding fusion of deuterium (heavy hydrogen) nuclei. If the scientists can prove that they do, an important step will have been taken toward controlled fusion.

Under a special arrangement, British and U.S. scientists are exchanging information on their fusion research. So far as is publicly known, both are working on similar lines, and so are the Russians. The basic problem in controlled fusion is to heat the material, usually deuterium, so hot that its nuclei will combine. This temperature is something like 100 million degrees C., and it must be held for an appreciable fraction of a second while the reaction takes place. Since all known materials turn into vapor at a few thousand degrees, the hot deuterium cannot be contained in any ordinary pressure vessel.

The best bet is believed to be a "magnetic bottle": an arrangement of magnetic fields that will grab the electrically charged deuterium nuclei and force them to stay close together while an electric current heats them very hot. In practice, a magnetic bottle is some sort of glass tube, often doughnut-shaped, filled with rarefied deuterium. When electric current is shot through it in the proper way, a hot, thread-thin spark flickers briefly in the center. This is deuterium pinched together by magnetic force. It is many times hot enough to melt the glass of the tube, but it never gets to touch it.

Devices of this general type have been developed in the U.S., Britain Russia, and probably other countries. Titular chief of such research for the U.S. Atomic Energy Commission is Dr. Arthur E. Ruark, 57. His job is to ride herd on projects in progress at Princeton, Livermore (Calif.), Los Alamos and other scientific centers. Probably the most ambitious of these is centered at Princeton. Its chief is Professor Lyman Spitzer Jr., 43, an astronomer who got into thermonuclear physics because the interiors of the stars are convenient test tubes for observing what happens at very high temperatures. Stars need no magnetic bottle; their gases are held together by their own gravitation. Earth-side gravitation is too feeble for this, so Spitzer's main job is to devise a leakproof magnetic bottle that can pinch-hit for the gravitation of the brighter stars.