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By Root 1416 0

well beyond that by the time the project was finished. But achieving breakeven was the minimum requirement for a fusion reactor, and that made the newest generation of tokamaks big and expensive. The United States was not the only country willing to spend hundreds of millions on big tokamaks: European countries were banding together to build one known as the Joint European Torus (JET), and Japan was planning to build a tokamak that would be known as JT-60. The three devices were similarly enormous and expensive. (They had some design differences, too. TFTR would be able to produce higher magnetic fields, and JET would be able to induce larger currents in the plasma; the JT-60 fell between the two extremes.)

In the late 1970s, morale in the magnetic fusion community was extremely high. Though they were still far away from breakeven—fusion energies were still ten thousand times smaller than the energy put in—they had been making steady progress over the years. As the machines got bigger and more expensive, scientists were able to get higher temperatures and densities in their plasmas, and to hold them for longer times. Physicists were confident that the new, large tokamaks being built would achieve breakeven, and perhaps go beyond. So were politicians. In 1980, President Jimmy Carter signed into law an act that promised to double the fusion budget in seven years—from nearly $400 million annually—and established the national goal of “the operation of a magnetic fusion demonstration plant at the turn of the twenty-first century.” The promised land was in sight. It would take only twenty years to get there.

For a tokamak, the promised land is not just breakeven. It is known as “ignition and sustained burn.” Unlike laser fusion devices, which have to create individual bursts of fusion energy, a magnetic fusion device like a tokamak can, in theory, run nonstop, producing continuous energy. Once scientists are able to get their magnetic bottles strong enough, they will be able to exploit this and keep a fusion reaction running indefinitely. The fusion reactions in the belly of the tokamak should suffice to keep the plasma hot, so after they get it started, the reaction will essentially run itself. All the scientists have to do is periodically inject some more deuterium and tritium fuel into the reactor and remove the helium “ash” from the plasma. Once you figure that out, you’ve got an unlimited source of power. Ignition and sustained burn are much better than mere breakeven: once you’ve got it, you’ve built a working reactor. And Carter’s plan called for developing just that.

By the time Ronald Reagan came into office, the climate for fusion was already changing. The OPEC crisis was fading into memory, and energy research was not a high priority for the new president. He scuttled Carter’s plan, and as budget deficits rose, fusion energy money began to disappear, $50 million hunks at a time. The panoply of glorious experiments planned in the 1970s began to crumble under increasing financial pressure. As magnetic fusion budgets dwindled, researchers struggled to save their precious tokamaks from the budget ax. A huge magnetic-mirror project that had already swallowed more than $300 million was scrapped just as it finished its eight-year construction and was about to be dedicated. 62 It never got turned on. One after another, new facilities—such as the “Elmo Bumpy Torus” and the “Impurity Studies Experiment”—died on the drawing board. The TFTR program was delayed, but not cancelled. The big tokamak was barely able to keep itself alive; everything else starved. With budgets in free fall, there was no room for anything other than the tokamak program, and even that was in jeopardy.

Despite the budget crunch, TFTR (and JET, JT-60, and a handful of other tokamaks worldwide) was steadily closing in on breakeven. It was holding plasmas for seconds at a time and achieving temperatures close to a hundred million degrees. Even with the improvements, breakeven was still a distance away, and the promised land of ignition and sustained burn