With lithium, more is definitely better

Nov 10, 2011
As more lithium is added (with increasing discharge number in yellow), the plasma light changes from red (from recycling of the deuterium fuel gas) to green (lithium emission from the edge of the plasma) and the overall (recycling) light levels decrease. Credit: Princeton Plasma Physics Laboratory

A team of scientists working at the U.S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL) has found that increasing the amount of lithium coating in the wall of an experimental fusion reactor greatly improves the ability of experimentalists to contain the hot, ionized gas known as plasma. Adding more lithium also enhances certain plasma properties aiding the reaction, the researchers found.

"The lesson here for confining is surprising and simple: When you use more and more , the plasma confinement gets better and better," said Rajesh Maingi, a physicist from the Oak Ridge National Laboratory (ORNL) who is on long-term assignment to PPPL. "This is not what we expected to see. We thought the effect would taper off at some point. But it doesn't. When it comes to plasmas, it's "the more, the merrier.'"

If plasma energy confinement is improved, a fusion reactor can, in principle, be made smaller and, therefore, cheaper. Energy confinement is a measure of how long (in seconds) power that is injected into the plasma stays in the plasma before leaking out to the walls.

Spraying lithium onto the of an experimental fusion device at PPPL known as the National Spherical Torus Experiment (NSTX) improves several other conditions for fusion, the experimenters found. The lithium reduced recycling—the problematic ricocheting of particles into the vessel wall and back into the plasma (Figure 1). Recycling leads to cooling, contamination, and, ultimately, dissipation of the energy of the plasma. In addition to reducing recycling, the lithium coating—and enhanced coatings based on it—also enhanced the reaction by decreasing chaotic instabilities both at the plasma's edge, and also on a larger scale.

The experiment's results indicate that fusion machine designers may be able to reduce the size and the level of heating in future devices designed to use lithium coating technologies.

Explore further: Physicists unlock nature of high-temperature superconductivity

More information: This work recently appeared in Physical Review Letters 107 (2011) 145004.

The work is being presented at the 53rd Annual Meeting of the American Physical Society Division of Plasma Physics, being held Nov. 14-18, in Salt Lake City, Utah.

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User comments : 10

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Cynical1
4.5 / 5 (2) Nov 10, 2011
It sure seems like complex things turn out to be easier than first thought...
I can't wait to see what's next...
antialias_physorg
4.8 / 5 (5) Nov 11, 2011
Does the lithium get used up/contaminated? Does the effect degrade over time?

If not then this is really a surprisingly simple (and relatively cheap) way to make things better.

rawa1
1.4 / 5 (11) Nov 11, 2011
Some people are apparently still willing to support the expensive and yet unsuccessful experiments leading to centralized energy sources, while they're ignoring twenty years of successful research of Piantelli and Focardi and the E-Cat technology, which is apparently based on this research.
Scottingham
2.3 / 5 (4) Nov 11, 2011
Fusion is good for one thing: making neutrons.
Fission is good for making energy.

The two go hand in hand in my opinion. Use the fusion to enrich depleted Uranium (versus centrifuges), use fission to get the sweet sweet energy.
antialias_physorg
4.5 / 5 (2) Nov 11, 2011
Use the fusion to enrich depleted Uranium (versus centrifuges)

Fusion does not 'enrich' Uranium.

Even if you were to create uranium using fusion (something that is not impossible - just very, very hard): The energy you then get out by fission of said uranium is at least as much as you put in in the first place (actually much less because a nuclear reactor only uses a small percentage of the uranium supplied)

There is no such thing as a free lunch.

Using your 'chain' of energy production would be a very bad investment (to use an euphemism for 'colossal waste')
Scottingham
1 / 5 (1) Nov 11, 2011
I know fusion doesn't...the neutrons produced by the fusion would. I'm fairly certain though that a fissed Uranium atom produces much more energy than it would take to create the isotope that underwent the fission (e=mc^2). Also, once a certain % of Uranium was turned into fissionable material, it could then become self-sustained with an integral fast reactor design.
flashgordon
5 / 5 (1) Nov 11, 2011
I'm sorry I don't have anything more constructive to say other than, "today seems to be fusion energy day!"
epicurious
not rated yet Nov 11, 2011
umm, I'm no physicist, but I'm pretty sure plasma physics doesn't really have anything to do with LENR
Some people are apparently still willing to support the expensive and yet unsuccessful experiments leading to centralized energy sources, while they're ignoring twenty years of successful research of Piantelli and Focardi and the E-Cat technology, which is apparently based on this research.

antialias_physorg
5 / 5 (1) Nov 11, 2011
Scottingham: Please take an introductory course to fission. (and also to nucleosynthesis). I don't even know where to begin to explain on how many counts your post is wrong.

... on second thought maybe I do: In every particular respect.
Uzza
not rated yet Nov 14, 2011
Chaining a fission reactor with a fusion reactor is a good idea if done correctly.
Using normal fission reactors today it would not work because they use solid fuel elements, which causes nonuniform fuel burnup, which leads to needing constant fuel reshuffling.
Engineering the entire plant would also be a very hard job.

Combining the fusion reactor with the principles of Molten Salt Reactors would allow you to combine fission and fusion in a synergistic system much easier, and minimizing wasting the "free" neutrons from the fusion reactor.