IN THE winter of 1968 three British physicists went to Moscow to examine a machine called a tokamak. This fusion reactor was a newly devised competitor to America’s approach to fusion, known as the stellarator. The Russians said the tokamak left the stellarator in the dust. The Americans demurred. But the British found that the Russians were right. The tokamak was far better than the stellarators of the day at holding in place the hot soup of atomic nuclei and electrons, called plasma, that is fusion’s fuel. Stellarators thus dwindled, and the tokamak became the preferred way to try to turn fusion into a practical and useful technology.
Fusion’s promise was of copious, safe, clean power generated from deuterium, a heavy isotope of hydrogen that makes up about 0.016% of the “H” in “H2O”, and tritium, an even heavier form of hydrogen that can be made easily from lithium. Fusing deuterium and tritium generates helium (and also a neutron), together with a lot of energy. But that promise has not been fulfilled. An old joke—that commercial fusion is 30 years away, and always will be—is more true than funny. The latest tokamak, the International...Continue reading
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