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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...
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