We are now getting a meaningful advance on fusion reactors here. This is obviously a good start that also opens the door to moreexperimentation. We may get something out of those billions spentyet.
I have generally been dismissive of what is ironically called BigScience simply because the experiment becomes an end in itself witheveryone conspiring to keep the experiment running even past any hopeof a breakthrough. Yet sometimes a breakthrough in thinking orcomputer modeling ability comes along and puts it all back on track.
So bravo for this one!
Mug handles couldhelp hot plasma give lower-cost, controllable fusion energy
by Hannah Hickeyfor UW News
San Diego CA (SPX)Oct 12, 2012
http://www.energy-daily.com/reports/Mug_handles_could_help_hot_plasma_give_lower_cost_controllable_fusion_energy_999.html
Researchersaround the world are working on an efficient, reliable way to containthe plasma used in fusionreactors, potentially bringing down thecost of this promising but technically elusive energy source. A newfinding from the University of Washington could help contain andstabilize the plasma using as little as 1 percent of the energyrequired by current methods.
"Allof a sudden the current energy goes from being almost too much toalmost negligible," said lead author Thomas Jarboe, a UWprofessor of aeronautics and astronautics. He presents the findingsthis week at the International Atomic Energy Association's 24thannual Fusion EnergyConference in San Diego.
The new equipmentlooks like handles on a coffee mug - except they attach to a vesselcontaining a million-degree plasma that is literally too hot tohandle.
Most people know about nuclear fission, the commercial typeof nuclearpower generated from splitting large atoms intwo. Still under research isnuclear fusion, which smashes twosmall atoms together, releasing energy without requiring rareelements or generating radioactive waste.
Of course, there's acatch - smashing the atoms together takes a lot of energy, andscientists are still working on a way to do it so you get out moreenergy than you put in. The sun is a powerful fusion reactor but wecan't recreate a full-scale sun on Earth.
Aninternational project in France is building a multibillion-dollarfusion reactor to see whether a big enough reactor cangenerate fusion power.
The reactor in Francewill inject high-frequency electromagnetic waves and high-speedhydrogen ions to sustain the plasma by maintaining an even hotter100-million-degree operating temperature and enclosing it withmagnetic fields.
"That methodworks," Jarboe said, "but it's extremely inefficient andexpensive, to the point that it really is a major problem withmagnetic confinement."
For two decadesJarboe's team has worked on helicity injection as a more efficientalternative. Spirals in the plasma produce asymmetric currents thatgenerate the right electric and magnetic fields to heat and confinethe contents. Plasma is so hot that the electrons have separated fromthe nuclei. It cannot touch any walls and so instead is contained bya magnetic bottle. Keeping the plasma hot enough and sustaining thosemagnetic fields requires a lot of energy.
"We would driveit until it was unstable," Jarboe said of his approach. "Likeyou twist up a rope, the plasma twists up on itself and makes theinstability and makes the current drive."
Results showed the UWstrategy required less energy than other methods, but the system wasunstable, meaning that if conditions change it could wobble out ofcontrol. It's like a stick balancing on one end, which is stable atthat moment, but is likely to come crashing down with any nudge. Inthe case of plasma, unstable equilibrium means that a twist in theplasma could cause it to escape and potentially lead to a costlyreactor shutdown.
Instability was amajor impediment to applying the UW method.
"The big issue iswhether, when you distort the bottle, it will leak," Jarboesaid.
By contrast, in astable equilibrium, any shift will tend to come back toward theoriginal state, like a ball resting at the bottom of a bowl that willsettle back where it started.
"Here we imposedthe asymmetric field, so the plasma doesn't have to go unstable inorder for us to drive the current. We've shown that we can sustain astable equilibrium and we can control the plasma, which means thebottle will be able to hold more plasma," Jarboe said.
The UW apparatus usestwo handle-shaped coils to alternately generate currents on eitherside of the central core, a method the authors call imposed dynamocurrent drive. Results show the plasma is stable and the method isenergy-efficient, but the UW research reactor is too small to fullycontain the plasma without some escaping as a gas. Next, the teamhopes to attach the device to a larger reactor to see if it canmaintain a sufficiently tight magnetic bottle.
The research is fundedby the U.S. Department of Energy. Co-authors are Brian Nelson,research associate professor of electrical engineering; and researchassociate Brian Victor, research scientists David Ennis, NathanielHicks, George Marklin and Roger Smith and graduate students ChrisHansen, Aaron Hossack,
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