The Electric Tokamak

When Robert Taylor graduated from UCLA in the 1970s, people were lining up at gas pumps, and the country’s fusion research budget was burgeoning. “There was an explosion in support for energy research,” he recalls.
Taylor headed east to MIT for a few years, then returned to UCLA with some new ideas about how best to bottle up the artificial suns of nuclear fusion. In the late ’70s he began a research project that, boasts the UCLA professor of mechanical, aerospace and nuclear engineering, “hasn’t been canceled since.”
But constructing a magnetic bottle to contain a burning plasma, once thought relatively easy by scientists flushed with post-World War II successes in nuclear and radar technology, has proven far from simple. “You have to keep the plasma hot for seconds at a time,” Taylor explains, “and it’s wriggling around, like Jell O, and it’s whipping through the magnetic field. We just didn’t understand the complexities.”
As scientists began to grapple with the complexities, they developed various designs for bottles. The most successful was a donut shaped machine, invented in the Soviet Union, called the “tokamak,” a Russian acronym for “torroidal magnetic chamber.” The tokamak’s donut, or torus, is wrapped with a coil that creates a magnetic field spiraling through its center. Because charged particles tend to travel along the lines of a magnetic field, it was hoped that the plasma, too, would circulate through the torroidal chamber. And some of it actually did.
Unfortunately, some of the plasma leaked out the sides of the torus, especially as temperatures and pressure rose to the levels necessary to compel the atomic nuclei to meet and fuse. The motion of the plasma through the torus, it turned out, was not smooth like a flowing stream, but turbulent like a waterfall. Taylor likens it to a traffic jam on the freeway: “Everything is okay as long as people stay in their lanes and maintain a safe distance,” he notes. “But if you get a couple of guys who are changing lanes or don’t maintain their distance, then it gets messed up for everyone, and you have a pileup. In a tokamak, this pileup is called turbulence, and it stops the show.”
Over the decades, scientists have found ways to reduce turbulence and keep the plasma in a tokamak bottled up long enough to initiate fusion. In 1995, scientists at Princeton’s TFTR achieved scientific break even, whereby their tokamak briefly produced as much energy as it consumed. The next step was the vast international collaboration called ITER, which is expected to produce fusion energy at the rate of a commercial power plant by the year 2010.
In the view of some researchers, ITER’s complexity makes it far too expensive and finicky to be practical. But many other scientists, including Taylor, believe that ITER will eventually succeed. The fact that the basic design of the ITER tokamak was developed when the fusion research budget was huge and the country’s sense of urgency regarding alternative energy sources had hit a peak, Taylor believes, motivated people to prematurely lock onto a solution -- and not necessarily the best one. Today, with research budgets down and relatively few Americans expressing concern about their energy future, Taylor sees an opportunity to search out a new approach to fusion. “In a sense,” he says, “I’m very grateful for the current malaise in the fusion community.”
Seizing the moment, Taylor and his UCLA colleagues are exploring a promising new approach to designing a tokamak that would be far more efficient than the one at Princeton. The idea is to minimize leaks from the tokamak by causing the ring of plasma inside it to rotate rapidly the short way around the donut, like smoke in a smoke ring. The rotation of a smoke ring is what allows it to hang together; something similar should happen with the tokamak plasma. Rotation of the charged particles of the plasma ring is achieved by exposure to electric fields; hence, Taylor calls his device the electric tokamak.
In standard tokamaks, like the machine at Princeton or the proposed one at ITER, leaks are prevented by using extremely powerful magnetic fields. If, as Taylor believes, rotation can help to plug the leaks, much smaller magnetic fields will be required. Smaller magnetic fields mean a cheaper machine. “What is remarkable about Taylor,” says Steven Cowley, a UCLA physicist who has made vital contributions to putting the electric tokamak on a strong theoretical footing, “is that he finds ways to build things for nothing. He’s a sort of green thumbed guy in experimental areas.”
An example of Taylor’s innovative thinking is the magnets with which he is working. Most tokamaks use copper, an expensive metal that is difficult to form and weld. Taylor makes his magnets, which do not have to be as powerful as in other machines, out of aluminum. Though aluminum does not conduct electricity as well as copper, it conducts it well enough and provides a key to creating an economical tokamak. “For about $4 million,” Cowley explains, “Taylor can build a machine that’s bigger than the one at Princeton, which cost around $1 billion.”
Taylor has built a prototype of the electric tokamak in the basement of Boelter Hall. Construction of the full scaled machine awaits completion of the Science and Technology Research Building on UCLA’s west campus and funding from the U.S. Department of Energy. “This machine,” Taylor insists, “has the potential to take it all the way. And if it works, it will sell like hotcakes. You could almost have one in your backyard!”


Power Plays...
The Electric Tokamak The Numerical Tokamak Laser Fusion
Advanced Technology and Materials Outer Space in a Bottle


CHALLENGE - Spring 1997 || CHALLENGE MAGAZINE || RESEARCH@UCLA