We are now getting a meaningful advance on fusion reactors here.
This is obviously a good start that also opens the door to more
experimentation. We may get something out of those billions spent
yet.
I have generally been dismissive of what is ironically called Big
Science simply because the experiment becomes an end in itself with
everyone conspiring to keep the experiment running even past any hope
of a breakthrough. Yet sometimes a breakthrough in thinking or
computer modeling ability comes along and puts it all back on track.
So bravo for this one!
Mug handles could
help hot plasma give lower-cost, controllable fusion energy
by Hannah Hickey for UW News
San Diego CA (SPX) Oct 12, 2012
Researchers
around the world are working on an efficient, reliable way to contain
the plasma used in fusionreactors, potentially bringing down the
cost of this promising but technically elusive energy source. A new
finding from the University of Washington could help contain and
stabilize the plasma using as little as 1 percent of the energy
required by current methods.
"All
of a sudden the current energy goes from being almost too much to
almost negligible," said lead author Thomas Jarboe, a UW
professor of aeronautics and astronautics. He presents the findings
this week at the International Atomic Energy Association's 24th
annual Fusion EnergyConference in San Diego.
The new equipment
looks like handles on a coffee mug - except they attach to a vessel
containing a million-degree plasma that is literally too hot to
handle.
Most people know about nuclear fission, the commercial type
of nuclearpower generated from splitting large atoms in
two. Still under research isnuclear fusion, which smashes two
small atoms together, releasing energy without requiring rare
elements or generating radioactive waste.
Of course, there's a
catch - smashing the atoms together takes a lot of energy, and
scientists are still working on a way to do it so you get out more
energy than you put in. The sun is a powerful fusion reactor but we
can't recreate a full-scale sun on Earth.
An
international project in France is building a multibillion-dollar
fusion reactor to see whether a big enough reactor can
generate fusion power.
The reactor in France
will inject high-frequency electromagnetic waves and high-speed
hydrogen ions to sustain the plasma by maintaining an even hotter
100-million-degree operating temperature and enclosing it with
magnetic fields.
"That method
works," Jarboe said, "but it's extremely inefficient and
expensive, to the point that it really is a major problem with
magnetic confinement."
For two decades
Jarboe's team has worked on helicity injection as a more efficient
alternative. Spirals in the plasma produce asymmetric currents that
generate the right electric and magnetic fields to heat and confine
the contents. Plasma is so hot that the electrons have separated from
the nuclei. It cannot touch any walls and so instead is contained by
a magnetic bottle. Keeping the plasma hot enough and sustaining those
magnetic fields requires a lot of energy.
"We would drive
it until it was unstable," Jarboe said of his approach. "Like
you twist up a rope, the plasma twists up on itself and makes the
instability and makes the current drive."
Results showed the UW
strategy required less energy than other methods, but the system was
unstable, meaning that if conditions change it could wobble out of
control. It's like a stick balancing on one end, which is stable at
that moment, but is likely to come crashing down with any nudge. In
the case of plasma, unstable equilibrium means that a twist in the
plasma could cause it to escape and potentially lead to a costly
reactor shutdown.
Instability was a
major impediment to applying the UW method.
"The big issue is
whether, when you distort the bottle, it will leak," Jarboe
said.
By contrast, in a
stable equilibrium, any shift will tend to come back toward the
original state, like a ball resting at the bottom of a bowl that will
settle back where it started.
"Here we imposed
the asymmetric field, so the plasma doesn't have to go unstable in
order for us to drive the current. We've shown that we can sustain a
stable equilibrium and we can control the plasma, which means the
bottle will be able to hold more plasma," Jarboe said.
The UW apparatus uses
two handle-shaped coils to alternately generate currents on either
side of the central core, a method the authors call imposed dynamo
current drive. Results show the plasma is stable and the method is
energy-efficient, but the UW research reactor is too small to fully
contain the plasma without some escaping as a gas. Next, the team
hopes to attach the device to a larger reactor to see if it can
maintain a sufficiently tight magnetic bottle.
The research is funded
by the U.S. Department of Energy. Co-authors are Brian Nelson,
research associate professor of electrical engineering; and research
associate Brian Victor, research scientists David Ennis, Nathaniel
Hicks, George Marklin and Roger Smith and graduate students Chris
Hansen, Aaron Hossack,
How do we know the sun is a fusion reaction? www.thunderbolts.info
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