JUN 02, 2015

A Simpler Way To Create Fusion Power?

WRITTEN BY: Andrew J. Dunlop

Fusion power, the holy grail of energy generation. If researchers could get a fusion reactor going and keep it going, we could have clean, safe, almost limitless energy. But, for almost a hundred years, that's been a very big if. Researchers can create a fusion reaction in a laboratory, at very small scale, and at tremendous expense. The trick is containing the reaction so that it can become self-sustaining. The most promising method so far is containing the reaction inside a magnetic field. In an attempt to do this, researchers have constructed containment vessels called tokamaks, essentially doughnut shaped reaction chambers, fitted with extremely powerful electromagnets. So far though, no one's been able to contain a fusion reaction and keep it going. But researchers at the U.S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL) have recently published a paper showing that they may have figured out a way to contain a fusion reaction without using electromagnets. If their research pans out, it may bring the construction of working fusion reactors within our reach.

Fusion reactions occur at incredibly high temperatures, millions of degrees. Keep in mind that this is the same process that powers stars. So physical containment, that is, creating a chamber that can handle millions of degrees for any sustained period is just not physically possible. That's why researchers have been pursuing magnetic containment. It is the only method thought to be powerful enough to contain such a high energy, high temperature reaction. In the Sun and other stars, fusion reactions create structures called plasmoids, essentially balls of plasma contained within a self-generated magnetic field.

What the researchers at the PPPL have discovered is a way to generate these plasmiods artificially, without using solenoids, the large magnetic coils that wind around today's tokamaks. Fatima Ebrahimi, a physicist at both Princeton University and PPPL, and the PPPL paper's lead author says, "Understanding this behavior will help us produce plasmas that undergo fusion reactions indefinitely."

Through running a computer simulation that modeled the behavior of plasma and the formation of plasmoids in three dimensions thoughout a tokamak's vacuum vessel, Ebrahimi and her team found that once initiated, plasmiods can form and maintain their own magnetic fields. Interestingly, this was a case of simply trying something that had never been tried before. It was the first time researchers tried modeling plasmoids in conditions that closely mimicked those within an actual tokamak. Other scientists have tried modeling plasma, but only a thin slice. Apparently, in trying to simplify this process down to two dimensions, previous attempts failed to capture the full range of plasma behavior.

We should not, however start deconstructing all of our current power stations just yet. Ebrahimi, wants to stress that, though promising, these are the results of a simulation. But the simulations are, according to Ebrahimi "only the beginning of even more exciting work that will be done on PPPL equipment." Ebrahimi and her team will be able see if their findings work in the real world when PPPL's National Spherical Torus Experiment-Upgrade (NSTX-U) begins operating later this year. Of course, if that pans out, we may start to see fusion generating plants popping up all over the globe.

(Sources: phys.org, wikipedia, the Princeton Plasma Physics Lab)