Princeton Takes Big Step Toward Fusion Power

Temperatures 10 times hotter than the core of the sun have been generated in a laboratory at Princeton University, it was announced Thursday, marking a milestone in the quest for fusion power.

A temperature of 200 million degrees Celsius, or 360 million degrees Fahrenheit, was reached for about one-fifth of a second at Princeton’s Plasma Physics Lab on the New Jersey campus, scientists reported.

“No previous laboratory experiment has ever achieved such high temperatures,” said Harold Furth, director of the lab, the nation’s lead center for research on magnetic fusion.

That is about the temperature that scientists believe will have to be sustained if fusion power is ever to become a practical source of energy.

The development of fusion power would forever free the world of the threat of energy shortages because fusion plants could draw their fuel from seawater, a virtually unlimited supply.

All nuclear plants today are fission plants, and they work by splitting atoms of uranium. As the atoms split, they release enormous amounts of heat, which is then used to generate electricity. But the fission process also generates dangerous radioactive byproducts, and uranium is an expensive and limited resource.

Scientists have dreamed for years of generating electricity by fusion, the energy that drives the stars. In the fusion process, hydrogen isotopes of deuterium and tritium are compressed together in extreme heat until they fuse to form helium, a process that also releases prodigious amounts of energy.

The problems involving fusion stem primarily from two areas: how do you get the fuel hot enough, and what do you hold it in after you get it that hot?

The success at Princeton demonstrates that scientists are nearly within reach of a solution to both of those questions, several experts said Thursday.

“It’s a big step forward,” said David Baldwin, deputy associate director for the magnetic fusion program at California’s Lawrence Livermore Laboratory. “They are really on a roll.”

The next step will be to see if the temperature can be sustained for longer periods, Baldwin said.

The temperature achieved at Princeton is by far the highest ever recorded in a laboratory, Energy Secretary John S. Herrington said, signaling “a major milestone in progress toward the development of fusion energy.”

“We’re all very encouraged by it,” said Burton D. Fried, a nuclear physics professor at UCLA who has just returned from a tour of duty at Europe’s lead center for fusion research, located near Culham, England. “But the Europeans are getting similar results.”

While not achieving as high a temperature, the Europeans have been able to sustain the reaction for a longer period, Fried said.

The next big hurdle is to get as much energy out of a fusion reaction as it takes to create it, and the results at Princeton indicate that is clearly possible, according to several scientists. Some scientists said that achievement--called the “break-even point”--could be reached as early as next year.

The high temperatures were achieved last month at Princeton using the tokamak fusion test reactor. The reactor creates a magnetic field in the shape of a doughnut, and the field holds the deuterium and tritium fuel suspended, providing what is called a “magnetic bottle.”

Scientists said Thursday that they had been able to improve the heat-insulation properties of the magnetic bottle, thus keeping more of the heat confined to the fuel area and making the high temperature possible.

Although there are still many technological problems to overcome, recent progress in fusion research prompted one expert Thursday to speak glowingly of what the future could hold.

“I think it would be easier (to build a fusion plant) than it would be to build another shuttle,” UCLA nuclear engineering professor Robert Taylor said, reflecting on the significance of the Princeton announcement. That kind of statement would have been virtually unthinkable a few years ago.

The irony of it all, however, is that the successes are coming at a time when many scientists see the United States as drifting away from its commitment to fusion research.

“With falling oil prices, the popular view is that the energy crisis has gone away,” said UCLA’s Fried.

Fried said funding for fusion research has been cut back at the rate of 10% to 15% per year, and “that adds up.”

“It is not a high priority goal (in the United States),” he said.

He said that during his recent tour of duty at the European fusion center, “I heard no such gloom and doom.”

“The Europeans don’t seem to be slacking off,” he added. “They have got their act together.”