Nav: Home

Lithium -- it's not just for batteries: It can also reduce instabilities in fusion plasmas

February 06, 2018

You may be most familiar with the element lithium as an integral component of your smart phone's battery, but the element also plays a role in the development of clean fusion energy. When used on tungsten surfaces in fusion devices, lithium can reduce periodic instabilities in plasma that can damage the reactor walls, scientists have found.

The results, demonstrated by scientists at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) and collaborators on China's Experimental Advanced Superconducting Tokamak (EAST) found that lithium powder can eliminate instabilities known as edge-localized modes (ELMs) when used to coat a tungsten plasma-facing component called the "divertor" -- the unit that exhausts waste heat and particles from plasma that fuels fusion reactions. If left alone, such instabilities can damage the divertor and cause fusion reactions to fizzle.

The results are good news for future devices that plan to use tungsten for their own divertors that are designed to work with lithium.

Past experiments with lithium powder on EAST have confirmed the metal's ability to eliminate or reduce the frequency and intensity of periodic bursts of ELMs that occur in the outer edge of plasmas that can damage the divertor. ELMs develop regularly when the plasma enters a high-energy state known as high-confinement mode, or H-mode, which holds heat within the plasma more efficiently. ELMs can also unleash large amounts of heat that damage the plasma-facing components and release eroded material that can enter the plasma and cool the fusion reactions.

During the past experiments, EAST's upper and lower divertors were coated with light and porous carbon rather than the heavy metal tungsten. "So, the question was whether lithium will have the same effect on tungsten walls as it does with carbon walls," said PPPL physicist Rajesh Maingi, lead author with Jiansheng Hu of the Institute of Plasma Physics at the Chinese Academy of Sciences (ASIPP) of a paper describing the results in the journal Nuclear Fusion.

The issue was in question because recent research on other doughnut-shaped tokamaks, such as the Axi-Symmetric Divertor Experiment-Upgrade (ASDEX-U) in Germany, have suggested that plasma-facing components made of tungsten actually reduce the ability of lithium coatings to control ELMs. Lithium was injected into ASDEX-U via large fast pellets, as compared with the lithium powder that was gravitationally injected into the EAST experiments.

In the recent experiments, researchers manipulated the plasma within EAST so that it exhausted its waste heat on the upper of the two divertors within the tokamak. Unlike the lower divertor, which was made of carbon, the upper divertor is fabricated from tungsten.

The results showed that lithium injected into plasma in contact with tungsten reduces ELMs just as much as lithium does when the plasma exhausts its heat on carbon. Physicists now have increased confidence that the techniques used to reduce ELMs in current fusion machines will be able to reduce ELMs in larger machines in the future, as long as they are designed to be compatible with lithium.

The research team noted that it became easier to eliminate ELMs as the experiments progressed, suggesting that elimination could require less lithium as time went on. Scientists would therefore like to find a way to regulate how much lithium is injected into the plasma, perhaps reducing the injection rate once the ELMs have disappeared to control the lithium inventory and optimize the performance of the plasma.
-end-
This research was funded by the DOE Office of Science together with the National Key Research and Development Program of China, the National Nature Science Foundation of China, and the National Magnetic Confinement Fusion Science Program of China. The team included scientists from PPPL, ASIPP, Johns Hopkins University, the Department of Applied Physics in China's Hunan University, Oak Ridge National Laboratory, and General Atomics.

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 largest single 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, please visit science.energy.gov

DOE/Princeton Plasma Physics Laboratory

Related Plasma Articles:

Table top plasma gets wind of solar turbulence
Scientists from India and Portugal recreate solar turbulence on a table top using a high intensity ultrashort laser pulse to excite a hot, dense plasma and followed the evolution of the giant magnetic field generated by the plasma dynamics.
Getting the biggest bang out of plasma jets
Capillary discharge plasma jets are created by a large current that passes through a low-density gas in what is called a capillary chamber.
Neptune: Neutralizer-free plasma propulsion
Plasma propulsion concepts are gridded-ion thrusters that accelerate and emit more positively charged particles than negatively charged ones.
UCLA researchers discover a new cause of high plasma triglycerides
People with hypertriglyceridemia often are told to change their diet and lose weight.
Where does laser energy go after being fired into plasma?
An outstanding conundrum on what happens to the laser energy after beams are fired into plasma has been solved in newly-published research at the University of Strathclyde.
New feedback system could allow greater control over fusion plasma
A physicist has created a new system that will let scientists control the energy and rotation of plasma in real time in a doughnut-shaped machine known as a tokamak.
PPPL scientist uncovers physics behind plasma-etching process
PPPL physicist Igor Kaganovich and collaborators have uncovered some of the physics that make possible the etching of silicon computer chips, which power cell phones, computers, and a huge range of electronic devices.
Calculating 1 billion plasma particles in a supercomputer
At the National Institutes of Natural Sciences National Institute for Fusion Science (NIFS) a research group using the NIFS 'Plasma Simulator' supercomputer succeeded for the first time in the world in calculating the movements of one billion plasma particles and the electrical field constructed by those particles.
Anti-tumor effect of novel plasma medicine caused by lactate
Nagoya University researchers developed a new physical plasma-activated salt solution for use as chemotherapy.
Clarifying the plasma oscillation by high-energy particles
The National Institute for Fusion Science has developed a new code that can simulate the movement of plasma and, simultaneously, the movement of particles circulating at high speeds.

Related Plasma Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Changing The World
What does it take to change the world for the better? This hour, TED speakers explore ideas on activism—what motivates it, why it matters, and how each of us can make a difference. Guests include civil rights activist Ruby Sales, labor leader and civil rights activist Dolores Huerta, author Jeremy Heimans, "craftivist" Sarah Corbett, and designer and futurist Angela Oguntala.
Now Playing: Science for the People

#521 The Curious Life of Krill
Krill may be one of the most abundant forms of life on our planet... but it turns out we don't know that much about them. For a create that underpins a massive ocean ecosystem and lives in our oceans in massive numbers, they're surprisingly difficult to study. We sit down and shine some light on these underappreciated crustaceans with Stephen Nicol, Adjunct Professor at the University of Tasmania, Scientific Advisor to the Association of Responsible Krill Harvesting Companies, and author of the book "The Curious Life of Krill: A Conservation Story from the Bottom of the World".