Energy

Nuclear fusion breakthrough breathes life into the overlooked Z-pinch approach

Nuclear fusion breakthrough br...
The Z-pinch confinement system at the University of Washington
The Z-pinch confinement system at the University of Washington
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The Z-pinch confinement system at the University of Washington
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The Z-pinch confinement system at the University of Washington
The team behind the nuclear fusion discovery at the University of Washington, from left to right, Anton Stepanov, Ellie Forbes, Elliot Claveau, Yue Zhang, Toby Weber, Brian Nelson, and Uri Shumlak
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The team behind the nuclear fusion discovery at the University of Washington, from left to right, Anton Stepanov, Ellie Forbes, Elliot Claveau, Yue Zhang, Toby Weber, Brian Nelson, and Uri Shumlak

Nuclear fusion holds untold potential as a source of power, but to recreate the colliding atomic nuclei taking place inside the Sun and generate inexhaustible amounts of clean energy scientists will need to achieve remarkable things. Tokamak reactors and fusion stellarators are a couple of the experimental devices used in pursuit of these lofty goals, but scientists at the University of Washington (UW) are taking a far less-frequented route known as a Z-pinch, with the early signs pointing to a cheaper and more efficient path forward.

In order to mimic the conditions inside the Sun, where hydrogen atoms smash together to form helium atoms and release gargantuan amounts of energy with no harmful by-products, we need a whole lot of heat and a whole lot of pressure.

Forming a stream of plasma and holding it in place long enough for these nuclear reactions to occur, either in a twisted loop or a neat donut shape, are the techniques employed by devices like Germany's wonky Wendelstein 7-X fusion reactor and China's Experimental Advanced Superconducting Tokamak. But this approach has its drawbacks, relating to the magnetic coils needed to suspend the ring of plasma, as study author Uri Shumlak explains to New Atlas.

"Magnetic field coils drive fusion devices to larger size and larger costs," he says. "The coils are also particularly sensitive to neutron damage, which requires more shielding, further driving size and costs."

A more efficient way to achieve these streams of plasma may be what is known as a Z-pinch confinement system. Rather than intricate webs of expensive magnetic coils, these systems pin the plasma in place with an electromagnetic field generated within the plasma itself. Z-pinch systems have been referred to as the dark horse of the nuclear fusion race, as the upside is a far simpler plasma configuration. The downside, however, is that instabilities cause distortions in the plasma that quickly cause it to hit the walls of the container vessel and collapse.

"Compressing and confining a plasma with magnetic fields in a Z-pinch configuration is prone to instabilities since the plasma can escape between the parallel magnetic field lines," Shumlak tells us. "The magnetic field forms circular loops around the plasma column which confines the plasma radially, but the plasma can form bulges, like an aneurysm, which locally weakens the magnetic field and allows the bulge to grow."

These problems have plagued the Z-pinch approach since its inception in the 1950s and effectively drove the development of tokamaks and stellarators, but the UW researchers say it still has something to give.

The team behind the nuclear fusion discovery at the University of Washington, from left to right, Anton Stepanov, Ellie Forbes, Elliot Claveau, Yue Zhang, Toby Weber, Brian Nelson, and Uri Shumlak
The team behind the nuclear fusion discovery at the University of Washington, from left to right, Anton Stepanov, Ellie Forbes, Elliot Claveau, Yue Zhang, Toby Weber, Brian Nelson, and Uri Shumlak

The reason for this, is that they believe they have figured out a way to stop the distortions that occur in the plasma and cause it to collapse. Through making slight adjustments to the behavior of the plasma by inducing what is known in fluid dynamics as sheared axial flow, the researchers were able to break new ground in their 50-cm-long (20-in) Z-pinch plasma column.

"The primary innovation is using plasma flows, specifically sheared axial flows," Shumlak tells us. "The sheared flow stabilizes the plasma by constantly smoothing the plasma surface and preventing the bulges from developing."

While the potential of sheared axial flow in Z-pinch plasma streams has been explored for years, the researchers write that this is the first time that they have produced "evidence of fusion neutron generation from a sheared-flow stabilized Z-pinch." More specifically, their flowing plasma was held in place 5,000 times longer than a static plasma, and they were able to observe energetic neutrons that are the telltale signs of nuclear fusion.

While enthused by the breakthrough, given the unstable history of Z-pinch confinement systems and uncertainty of nuclear fusion research as a whole, they are taking a cautiously optimistic outlook.

"As a scientist, I would state that we do not know for certain if this advance will lead to a new dawn," says Shumlak. "However, the results are particularly encouraging. Sheared flow stabilization of the Z-pinch approach has been thoroughly investigated, and the predictions of scaling to current performance have been demonstrated. The evidence is described in our Physical Review Letters article. If our current scientific understanding continues to hold, then we should be able to reach even higher performance."

The research was published in the journal Physical Review Letters.

Source: University of Washington

18 comments
VincentWolf
Fusion is a pipe dream. Wont happen even in the lifetimes of my great grand children or theirs either.
PeakSpecies
They are still a long ways away from achieving break-even fusion energy output. This article should have mentioned if radioactive tritium was involved in their reactions. Typically, those involved is such research projects have no idea how little time is left. It is unlikely that any of them have seen the following linked articles. UN chief: World has less than 2 years to avoid 'runaway climate change' https://thehill.com/policy/energy-environment/406291-un-chief-the-world-has-less-than-2-years-to-avoid-runaway-climate Climate change could plunge tens of millions of city dwellers into poverty by 2031 http://www.businessinsider.com/climate-change-could-plunge-tens-of-millions-into-poverty-by-2031-2016-10 A Horrifying New Study Found that the Ocean is on its Way to Suffocating by 2030 http://www.theinertia.com/environment/a-horrifying-new-study-found-that-the-ocean-is-on-its-way-to-suffocating-by-2030/ World on track to lose two-thirds of wild animals by 2020, major report warns http://www.theguardian.com/environment/2016/oct/27/world-on-track-to-lose-two-thirds-of-wild-animals-by-2020-major-report-warns The Threat of Global Warming causing Near-Term Human Extinction Temperature, carbon dioxide and methane http://arctic-news.blogspot.com/p/threat.html
bobthedog
@VincentWolf - Yes . . . and Man will never Fly... @PeakSpecies - Well, but at least they're *trying*... Stable fusion energy would solve a plethora of problems without as great an impact on the climate or the ecology as current means of energy production do. I can tell you that the people who were living near Chernobyl and Fukushima would have welcomed having a fusion reactor rather what they got. The least we can do is to leave the upcoming Peak Species - gigantic radioactive mutant cockroaches - an archaeological record of sound energy science to ease their way into becoming the dominant representatives of Planet Earth. *Go, Gigantic Radioactive Mutant Cockroaches!*
InfiniteSmile
PeakSpecies, I question the integrity of the news/blog websites you posted. The sky has been falling ever since the first newspaper has been published.
Skipjack
I have been following them for a while. Their design is really promising. So far they have been able to increase the input current by a factor of 5 and still maintain stability. From here, they have to triple it to 650 kA in order to reach "break even". For a commercial reactor, they need to double that again to 1250 kA. The great thing about the reactor is that it is really compact, which has aerospace applications.
Fletcher
The 1st controlled manmade fusion reaction occurred in 1958 (that's if you don't include a thermonuclear detonation) and has been reproduced done thousands of times since. The goal after this for a long time was to break-even, rather get energy output to be equal or greater than energy input and that goal was achieved by the United States in 2014. So now the goal is to make fusion affordable and numerous computer simulations are suggesting numerous ways to do this. Include the new breakthroughs in superconductors, lasers, train of thought or different approaches and the massive new infusion of funding because of numerous groups working above the break-even point and it is likely to happen in 5 to 10 years rather than the 20 we have always been told. As for PeakSpecies, you get the red pile and big spoon award of the day! Please, go back to listing what your told by big media and quite commenting on things you know very little about (and the papers you quote are opinionated articles not peer reviewed journals). The reality is we are killing our ocean’s (not with CO2- which is less than 2 tenths of a % of our atmosphere and has very little green house effect when compared to water vaper), through radioactive waste (current big offenders Fukushima and French dumping) and toxic dumping. As for the climate changing, well it does that every year cyclically (spring, summer, fall, and winter) but currently we are starting to feel the effects of 2 longer term weather cycles (grand solar minimum and magnetic pole shift) that will be hitting us over the next 10 to 30 years that will severally affect global weather and likely be the cause of billions to die not just starve. You won’t hear about that in the mainstream media so enjoy that new bite of information.
Fast Eddie
Hmmm....sometimes when we want to believe something, we don't make good decisions. That seems to be the history of fusion research. I vote to continue it, but given that controlled fusion is probably more than another 50 years from practicality, let's start using the fusion power source we already have: https://uploads.disquscdn.com/images/09597b104b84e91f1e31dae27c07cefbb9984224ce373d4fe4c98b503d0669c9.jpg
Mark T.
Skipjack4 wrote: "For a commercial reactor, they need to double that again to 1250 kA." I think your numbers are too low, unless this is a much bigger breakthrough that anybody knew, because the Z Machine is already ~20 times more powerful than that. The Z Machine "can now shoot around 26 million amperes (instead of 18 million amperes previously) in 95 nanoseconds" and "Sandia Labs recently proposed a conceptual 1 petawatt LTD Z-pinch power plant, where the electric discharge would reach 70 million amperes." https://en.wikipedia.org/wiki/Z_Pulsed_Power_Facility
Vixbie
@PeakSpecies I get you, but with the power of fusion we will be able to produce the massive amounts of bourbon that we will need while we watch the planet expire.
tsvieps
Fusion may still be worth some research. But fail-safe small scale fission reactors that run at low pressures, do not need water cooling, and burn up our present toxic nuclear wastes seem a lot closer and more worthy of larger scale investments. They also do not produce bomb fuels. The technical issue mainly seems to be materials that can hold liquid salt for a long time without corroding. Far from easy. But material science has advanced far in the last few decades.