Nav: Home

Simulations by PPPL physicists suggest that magnetic fields can calm plasma instabilities

August 15, 2016

Physicists led by Gerrit Kramer at the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) have conducted simulations that suggest that applying magnetic fields to fusion plasmas can control instabilities known as Alfvén waves that can reduce the efficiency of fusion reactions. Such instabilities can cause quickly moving charged particles called "fast ions" to escape from the core of the plasma, which is corralled within machines known as tokamaks.

Controlling these instabilities leads to higher temperatures within tokamaks and thus more efficient fusion processes. The research was published in the August issue of Plasma Physics and Controlled Fusion and funded by the DOE Office of Science (Fusion Energy Sciences).

"Controlling and suppressing the instabilities helps improve the fast-ion confinement and plasma performance," said Kramer, a research physicist at the Laboratory. "You want to suppress the Alfvén waves as much as possible so the fast ions stay in the plasma and help heat it."

The team gathered data from experiments conducted on the National Spherical Torus Experiment (NSTX) at PPPL before the tokamak was recently upgraded. Then they conducted plasma simulations on a PPPL computer cluster.

The simulations showed that externally applied magnetic perturbations can block the growth of Alfvén waves. The perturbations reduce the gradient, or difference in velocity, of the ions as they zoom around the tokamak. This process calms disturbances within the plasma. "If you reduce the velocity gradient, you can prevent the waves from getting excited," notes Kramer.

The simulations also showed that magnetic perturbations can calm Alfvén waves that have already formed. The perturbations alter the frequency of the plasma vibration so that it matches the frequency of the wave. "The plasma absorbs all the energy of the wave, and the wave stops vibrating," said Kramer.

In addition, the simulations indicated that when applied to tokamaks with relatively weak magnetic fields, the external magnetic perturbations could dislodge fast ions from the plasma directly, causing the plasma to cool.
-end-
Along with Kramer, the research team included scientists from General Atomics, Oak Ridge National Laboratory, the University of California, Los Angeles, and the University of California, Irvine.

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. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. 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

Climate Crisis
There's no greater threat to humanity than climate change. What can we do to stop the worst consequences? This hour, TED speakers explore how we can save our planet and whether we can do it in time. Guests include climate activist Greta Thunberg, chemical engineer Jennifer Wilcox, research scientist Sean Davis, food innovator Bruce Friedrich, and psychologist Per Espen Stoknes.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...