A step closer to nuclear fusion -bye bye Energy crisis

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Nuclear Fusion Just Got a Little Closer to
Becoming a Reality
Atomic fusion could produce limitless
energy—but scientists haven't been able to
harness it. But a novel experiment suggests
it could be achievable
By Michael LemonickFeb. 12, 2014
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Dr. Eddie Dewald
When physicists first split the atom in 1938,
in the process known as nuclear fission, the
feat led very quickly to the bombs that
destroyed Hiroshima and Nagasaki
and ended World War II. A mere decade or
so later this destructive force had been
tamed to power the first commercial nuclear
power plants. In the late 1940’s, meanwhile,
physicists forced atoms to combine against
their will to create hydrogen bombs in
what’s called nuclear fusion, and they
thought they could follow up in the civilian
sector. Fusion power planets, scientists
predicted in the 1950’s, might be right
around the corner.
That was just a tad optimistic. Controlled
fusion—which amounts to taming the same
awesome force that powers the Sun—has
turned out to be much more difficult and
more expensive than anyone guessed, and
more than a half-century on nobody’s
achieved it. Yet as a new paper just
published in Nature makes clear, they
haven’t given up. By focusing 192 powerful
lasers on a tiny sphere encasing 170
millionths of a gram of hydrogen, scientists
at Lawrence Livermore National Laboratory
forced atomic nuclei to combine, releasing a
whopping 17 kilojoules of energy. “It is not
surprising,” writes physicist Mark Herrmann
of Sandia National Laboratories in an
accompanying Nature commentary, “that
fusion scientists throughout the world are
cheering.”
(MORE: Europe-based Fusion Project Draws
Heat Over Funding
)
This might sound a bit over the top when
you consider how little hydrogen was
involved, and how little power it actually
released: 17 kilojoules represents the
amount of solar energy that falls on a sq.
yard (0.83 sq. m) of Earth (more or less) in
full daylight over 17 seconds—and this
fusion reaction lasted more
like .0000000001 second.
“It sounds very modest,” admitted lead
scientist Omar Hurricane at a press briefing.
“And it is. But it’s closer than anyone’s ever
gotten to ignition”—that is, the self-
sustaining process where the fusion
reaction can keep going on its own.
The reaction itself is simple: atomic nuclei
carry a positive charge, so they try to repel
each other. If you can overcome that
repulsion and let them crash together and
fuse, they release a burst of energy. And the
way you do that, says Hurricane, is “you get
them running toward each other at high
velocity.”
Inside the Sun, that’s no problem. That high
velocity comes from the 27-million-degree
temperatures at the Sun’s core, which keep
nuclei moving with enormous energy. Under
other circumstances, most of the nuclei
would just escape without colliding. But the
enormous pressures created by the Sun’s
gravity keep them confined indefinitely.
Sooner or later, they crash.
(MORE: Going to Mars via Fusion Power?
Could Be)
It’s no problem in an H-bomb either:
hydrogen fuel is heated and compressed by
an old-fashioned atomic bomb. The
compression doesn’t last long, but the
energy released in a fraction of a second is
hundreds of times more powerful than an
A-bomb. For a self-sustaining fusion
reaction, you somehow need to get
hydrogen very hot and keep it from
escaping. That’s the tough part. One
technique traps a gas of hydrogen atoms in
a magnetic “bottle,”
then heats the gas to millions of degrees
with high-energy radio waves.
But the Livermore scientists have long
focused on another method, known as
inertial fusion. They bombard a spherical
capsule of hydrogen with lasers from all
directions, vaporizing the container itself
and driving the hydrogen inward. “We need
to compress the capsule by a factor of 35,”
says Livermore physicist and co-author
Debbie Callahan. The capsule itself is a
fraction of an inch across, but the
compression, she says, “is equivalent to
compressing a basketball to the size of a
pea.”
When that happens, the temperature shoots
sky-high, the pressure reaches 150 billion
times atmospheric pressure on Earth, and
the hydrogen—more precisely, it’s a mixture
of deuterium and tritium, which are heavier
varieties of hydrogen—begins to fuse. “It’s
quite ferocious,” says Hurricane.
It will have to get a lot more ferocious to
deliver usable power, which would
presumably come from blasting one capsule
after another in unbroken succession. How
long it will take to make a commercial
reactor, says Hurricane, “is anybody’s guess.
We’re working like mad, but this is research
—it’s not a power plant, not a reactor.”
The same can be said for the magnetic
confinement technique, whose most
advanced experiment, the Joint European
Torus (JET), briefly produced 16 megawatts
of fusion energy back in 1997. That reaction
wasn’t self-sustaining either, and the
technical barriers to making this kind of
fusion work are no less daunting than those
the Livermore scientists face.
But don’t tell the scientists that. “We’ve
waited 60 years to get close to controlled
fusion, and we are now close in both
magnetic and inertial,” says Steven Cowley,
director of the Culham Center for Nuclear
Energy, in England, where JET is located. “We
must keep at it.”