Nav: Home

Powder, not gas: A safer, more effective way to create a star on Earth

December 23, 2019

A major issue with operating ring-shaped fusion facilities known as tokamaks is keeping the plasma that fuels fusion reactions free of impurities that could reduce the efficiency of the reactions. Now, scientists at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) have found that sprinkling a type of powder into the plasma could aid in harnessing the ultra-hot gas within a tokamak facility to produce heat to create electricity without producing greenhouse gases or long-term radioactive waste.

Fusion, the power that drives the sun and stars, combines light elements in the form of plasma -- the hot, charged state of matter composed of free electrons and atomic nuclei -- that generates massive amounts of energy. Scientists are seeking to replicate fusion on Earth for a virtually inexhaustible supply of power to generate electricity.

"The main goal of the experiment was to see if we could lay down a layer of boron using a powder injector," said PPPL physicist Robert Lunsford, lead author of the paper reporting the results in Nuclear Fusion. "So far, the experiment appears to have been successful."

¬The boron prevents an element known as tungsten from leaching out of the tokamak walls into the plasma, where it can cool the plasma particles and make fusion reactions less efficient. A layer of boron is applied to plasma-facing surfaces in a process known as "boronization." Scientists want to keep the plasma as hot as possible -- at least ten times hotter than the surface of the sun -- to maximize the fusion reactions and therefore the heat to create electricity.

Using powder to provide boronization is also far safer than using a boron gas called diborane, the method used today. "Diborane gas is explosive, so everybody has to leave the building housing the tokamak during the process," Lunsford said. "On the other hand, if you could just drop some boron powder into the plasma, that would be a lot easier to manage. While diborane gas is explosive and toxic, boron powder is inert," he added. "This new technique would be less intrusive and definitely less dangerous."

Another advantage is that while physicists must halt tokamak operations during the boron gas process, boron powder can be added to the plasma while the machine is running. This feature is important because to provide a constant source of electricity, future fusion facilities will have to run for long, uninterrupted periods of time. "This is one way to get to a steady-state fusion machine," Lunsford said. "You can add more boron without having to completely shut down the machine."

There are other reasons to use a powder dropper to coat the inner surfaces of a tokamak. For example, the researchers discovered that injecting boron powder has the same benefit as puffing nitrogen gas into the plasma -- both techniques increase the heat at the plasma edge, which increases how well the plasma stays confined within the magnetic fields.

The powder dropper technique also gives scientists an easy way to create low-density fusion plasmas, important because low density allows plasma instabilities to be suppressed by magnetic pulses, a relatively simple way to improve fusion reactions. Scientists could use powder to create low-density plasmas at any time, rather than waiting for a gaseous boronization. Being able to create a wide range of plasma conditions easily in this way would enable physicists to explore the behavior of plasma more thoroughly.

In the future, Lunsford and the other scientists in the group hope to conduct experiments to determine where, exactly, the material goes after it has been injected into the plasma. Physicists currently hypothesize that the powder flows to the top and bottom of the tokamak chamber, the same way the plasma flows, "but it would be useful to have that hypothesis backed up by modeling so we know the exact locations within the tokamak that are getting the boron layers," Lunsford said.
-end-
This research was supported by the DOE Office of Science (FES) and the Euratom research and training programme. The research group included collaborators from Germany's Max Planck Institute for Plasma Physics.

PPPL, on Princeton University's Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas -- ultra-hot, charged gases -- and to developing practical solutions for the creation of fusion energy. The Laboratory is managed by the University for the U.S. Department of Energy's Office of Science, which is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science

DOE/Princeton Plasma Physics Laboratory

Related Plasma Articles:

Plasma-driven biocatalysis
Compared with traditional chemical methods, enzyme catalysis has numerous advantages.
How bacteria protect themselves from plasma treatment
Considering the ever-growing percentage of bacteria that are resistant to antibiotics, interest in medical use of plasma is increasing.
A breakthrough in the study of laser/plasma interactions
Researchers from Lawrence Berkeley National Laboratory and CEA Saclay have developed a particle-in-cell simulation tool that is enabling cutting-edge simulations of laser/plasma coupling mechanisms.
Researchers turn liquid metal into a plasma
For the first time, researchers at the University of Rochester's Laboratory for Laser Energetics (LLE) have found a way to turn a liquid metal into a plasma and to observe the temperature where a liquid under high-density conditions crosses over to a plasma state.
How black holes power plasma jets
Cosmic robbery powers the jets streaming from a black hole, new simulations reveal.
Give it the plasma treatment: strong adhesion without adhesives
A Japanese research team at Osaka University used plasma treatment to make fluoropolymers and silicone resin adhere without any adhesives.
Chemotherapeutic drugs and plasma proteins: Exploring new dimensions
This review provides a bird's eye view of interaction of a number of clinically important drugs currently in use that show covalent or non-covalent interaction with serum proteins.
The coming of age of plasma physics
The story of the generation of physicists involved in the development of a sustainable energy source, controlled fusion, using a method called magnetic confinement.
Intense microwave pulse ionizes its own channel through plasma
More than 30 years ago, researchers theoretically predicted the ionization-induced channeling of an intense microwave beam propagating through a neutral gas (>103 Pa) -- and now it's finally been observed experimentally.
Plasma thruster: New space debris removal technology
A Japanese and Australian research group has discovered new technology to remove space debris using a single propulsion system in a helicon plasma thruster.
More Plasma News and Plasma Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.