Doe Science news source
The DOE Science News Source is a Newswise initiative to promote research news from the Office of Science of the DOE to the public and news media.
  • 2018-06-08 13:05:41
  • Article ID: 695555

Simulations of Magnetically Confined Plasmas Reveal a Self-Regulating Stabilizing Mechanism

A mysterious mechanism that prevents instabilities may be similar to the process that maintains the Earth's magnetic field.

  • Credit: Isabel Krebs, Princeton Plasma Physics Laboratory

    Helical plasma flow in the core of a tokamak in a nonlinear simulation. Red depicts positive values and blue depicts negative values of the poloidal velocity stream function. The black arrows illustrate the direction of the plasma flow within a toroidal cross section. (Figure shows a quarter of the torus.)

The Science

The hot ionized gas called a plasma is confined in a bagel-shaped tokamak by a strong magnetic field, part of which is generated by a strong electric current flowing through the plasma. Periodically, a sawtooth instability occurs. It causes the central plasma temperature to abruptly drop and then recover in a sawtooth pattern. The instability limits how much current can be concentrated in the center of the plasma. However, there are types of tokamak plasmas for which a previously unknown mechanism, called magnetic flux pumping, limits the current in the plasma center so that it stays just below the sawtooth threshold. Scientists were puzzled by how this self-regulating mechanism works. The results of highly complex numerical simulations now suggest a possible answer.

The Impact

The sawtooth instability can trigger other issues that lead to the deterioration or even loss of plasma confinement. Thus, hybrid scenarios in which magnetic flux pumping prevents the sawtooth instability are of interest. This is especially true for future large-scale fusion experiments, such as ITER. To extrapolate the accessibility and properties of hybrid scenarios to ITER, it is essential to understand the physics behind magnetic flux pumping. With the help of elaborate simulations, scientists are now able to find a possible explanation for this phenomenon.

Summary

The mechanism behind the magnetic flux pumping in the numerical simulations works as follows: if the central current profile is flat and if the central plasma pressure is sufficiently high, a quasi-interchange mode develops in the plasma’s core. The quasi-interchange mode generates a large-scale helical flow of plasma that—almost like a mixer—constantly stirs the central plasma. At the same time, the magnetic field in the plasma core is deformed.

This is where a dynamo effect comes in. The dynamo effect plays an important role for many astrophysical phenomena as well as for the mechanism that maintains the Earth's magnetic field. It describes how a particularly swirly movement of an electrically conducting fluid can reinforce an existing magnetic field. In the case of the Earth's magnetic field, the fluid is the liquid part of the Earth's iron core. In the case of the hybrid tokamak scenario, the fluid is the hot plasma in the center of the tokamak. In the latter case, it is through a dynamo effect that the helical plasma flow and the helical deformation of the magnetic field combine to give a negative voltage that keeps the central current flat. By keeping the current in the plasma center flat, the sawtooth instability is prevented.

The numerical simulations also explain how this magnetic flux pumping regulates itself: The quasi-interchange mode is known to work best if the central current is at a certain threshold—which coincides with the threshold for the sawtooth instability. Whenever the flux pumping mechanism becomes too strong, it weakens the quasi-interchange mode and therefore its own drive. This is how the strength of the flux pumping is limited so that it keeps the central current just below the threshold for the sawtooth instability.

Funding

The research was funded by Department of Energy (DOE) Office of Science, Fusion Energy Sciences; DOE Office of Advanced Scientific Computing Research; Scientific Discovery Through Advanced Computing (SciDAC) Center for Extended-Magnetohydrodynamic Modeling; and Max-Planck Princeton Center for Plasma Physics. The research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science user facility.

Publications

I. Krebs, S.C. Jardin, S. Günter, K. Lackner, M. Hoelzl, E. Strumberger, and N. Ferraro, “Magnetic flux pumping in 3D nonlinear magnetohydrodynamic simulations.” Physics of Plasmas 24, 102511 (2017). [DOI: 10.1063/1.4990704]

S.C. Jardin, N. Ferraro, and I. Krebs, “Self-organized stationary states of tokamaks.” Physical Review Letters 115, 215001 (2015). [DOI: 10.1103/PhysRevLett.115.215001]

Contact patient services
X
X
X
  • Filters

  • × Clear Filters

Carbon Nanotube Optics Poised to Provide Pathway to Optical-Based Quantum Cryptography and Quantum Computing

Researchers at Los Alamos and partners in France and Germany are exploring the enhanced potential of carbon nanotubes as single-photon emitters for quantum information processing. Their analysis of progress in the field is published in this week's edition of the journal Nature Materials.

New Tech Uses Isomeric Beams to Study How and Where the Galaxy Makes One of Its Most Common Elements

A new measurement using a beam of aluminum-26 prepared in a metastable state allows researchers to better understand the creation of the elements in our galaxy.

Scientists Use Neutrons to Take a Deeper Look at Record Boost in Thermoelectric Efficiency

Neutron facilities at Oak Ridge National Laboratory are aiding scientists in research to boost the power and efficiency of thermoelectric materials. These performance increases could enable more cost-effective and practical uses for thermoelectrics, with wider industry adoption, to improve fuel economy in vehicles, make power plants more efficient, and advance body heat-powered technologies for watches and smartphones.

The science behind pickled battery electrolytes

Argonne material scientists have discovered a reaction that helps explain the behavior of a key electrolyte additive used to boost battery performance.

Faster, Cheaper, Better: A New Way to Synthesize DNA

Researchers at the Department of Energy's Joint BioEnergy Institute (JBEI) based at Berkeley Lab have pioneered a new way to synthesize DNA sequences through a creative use of enzymes that promises to be faster, cheaper, and more accurate. DNA synthesis is a fundamental tool in the rapidly growing field of synthetic biology, in which organisms can be engineered to do things like decompose plastic and manufacture biofuels and medicines. This discovery could dramatically accelerate the pace of scientific discovery.

Scientists Create Continuously Emitting Microlasers With Nanoparticle-Coated Beads

Researchers have found a way to convert nanoparticle-coated microscopic beads into lasers smaller than red blood cells. These microlasers, which convert infrared light into light at higher frequencies, are among the smallest continuously emitting lasers of their kind ever reported and can constantly and stably emit light for hours at a time, even when submerged in biological fluids such as blood serum.

New Material for Splitting Water

Solar energy is clean and abundant, but when the sun isn't shining, you must store the energy in batteries or through a process called photocatalysis. In photocatalytic water splitting, sunlight separates water into hydrogen and oxygen. The hydrogen and oxygen can then be recombined in a fuel cell to release energy. Now, a new class of materials -- halide double perovskites -- may have just the right properties to split water, according to a newly published paper in Applied Physics Letters.

Large Outdoor Study Shows Biodiversity Improves Stability of Algal Biofuel Systems

A diverse mix of species improves the stability and fuel-oil yield of algal biofuel systems, as well as their resistance to invasion by outsiders, according to the findings of a federally funded outdoor study by University of Michigan researchers.

SLAC, Stanford Scientists Discover How a Hardy Microbe's Crystalline Shell Helps it Reel in Food

SLAC and Stanford scientists have discovered how some archaea thrive where other organisms would starve: Their crystalline shells not only protect them from the environment, but they also draw in nutrients through nanosized pores. Those nutrients concentrate in the space between the shell and the microbial cell, so what looks like a famine turns into a feast.

Scientists Make the First Molecular Movie of One of Nature's Most Widely Used Light Sensors

Scientists have made the first molecular movie of the instant when light hits a sensor that's widely used in nature for probing the environment and harvesting energy from light. The sensor, a form of vitamin A known as retinal, is central to a number of important light-driven processes in people, animals, microbes and algae, including human vision and some forms of photosynthesis, and the movie shows it changing shape in a trillionth of an eye blink.


  • Filters

  • × Clear Filters

Professor Emily Liu Receives $1.8 Million DoE Award for Solar Power Systems Research

Li (Emily) Liu, associate professor of nuclear engineering and engineering physics in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer Polytechnic Institute, has been selected by the U.S. Department of Energy Solar Energy Technologies Office (SETO) to receive a $1.8 million award to study high-temperature molten-salt properties and corrosion mechanisms.

Vasilis Fthenakis Receives IEEE's William R. Cherry Award

UPTON, NY; Vasilis Fthenakis, a Senior Scientist Emeritus at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory and Founder and Director of the Center for Life Cycle Analysis at Columbia University, will receive the 2018 William R. Cherry Award from the Institute of Electrical & Electronics Engineers (IEEE).

New PPPL director Steve Cowley is honored with knighthood by Queen Elizabeth II

Steven Cowley, newly named director of the U.S. Department of Energy's (DOE) Princeton Plasma Physics Laboratory (PPPL) effective July 1, has received a knighthood from Queen Elizabeth "for services to science and the development of nuclear fusion."

UVA Darden Releases Policy Playbook Identifying Six Actions to Catalyze Clean-Tech Innovation

Moving the needle on climate change will require substantive and disruptive innovation across multiple industry sectors. Public and private investment focused on a few key areas could have a significant impact, according to a new policy playbook released by the Batten Institute for Entrepreneurship and Innovation on 8 June.

Work Begins on New SLAC Facility for Revolutionary Accelerator Science

The Department of Energy's SLAC National Accelerator Laboratory has started to assemble a new facility for revolutionary accelerator technologies that could make future accelerators 100 to 1,000 times smaller and boost their capabilities.

Oak Ridge National Laboratory Launches America's New Top Supercomputer for Science

The U.S. Department of Energy's Oak Ridge National Laboratory unveiled Summit as the world's most powerful and smartest scientific supercomputer.

Takeuchi Receives European Inventor Award 2018 in the Non-EPO Countries Category

Prolific patent-holder won for inventing battery that increases the lifespan of implantable defibrillators fivefold, greatly reducing need for reoccurring surgery

Steve Kevan Named Next Director of Berkeley Lab's Advanced Light Source

After an international search, Stephen D. "Steve" Kevan has been named the new director of the Advanced Light Source (ALS) at the U.S. Department of Energy's Lawrence Berkeley National Laboratory.

International corrosion society elects first Sandia fellow

Sandia National Laboratories materials scientist David Enos has been elected a fellow of NACE International, the chief professional society for corrosion engineering. He is the first Sandia employee to receive the honor.

Power to the People

The University of Utah College of Engineering has received a $2 million grant to create a laboratory and develop new technology for communities with backup power sources, known as microgrids, so they can quickly and more securely operate in the event of a massive power outage due to a natural disaster or cyberattack.


  • Filters

  • × Clear Filters

New Tech Uses Isomeric Beams to Study How and Where the Galaxy Makes One of Its Most Common Elements

A new measurement using a beam of aluminum-26 prepared in a metastable state allows researchers to better understand the creation of the elements in our galaxy.

Simulations of Magnetically Confined Plasmas Reveal a Self-Regulating Stabilizing Mechanism

A mysterious mechanism that prevents instabilities may be similar to the process that maintains the Earth's magnetic field.

Seeing All the Colors of the Plasma Wind

2-D velocity imaging helps fusion researchers understand the role of ion winds (aka flows) in the boundary of tokamak plasmas.

Renewable Solvents Derived From Lignin Lowers Waste in Biofuel Production

New class of solvents breaks down plant biomass into sugars for biofuels and bioproducts in a closed-loop biorefinery concept.

Scientists Studying Nuclear Spin Make a Surprising Discovery

The size of a nucleus appears to influence the direction of certain particles emitted from collisions with spinning protons.

Simulating Turbulent Bubbly Flows in Nuclear Reactors

With a better understanding of bubbly flows, researchers can improve the safety and operation of our nuclear reactors.

Solving a Magnesium Mystery in Rechargeable Battery Performance

Study reveals surprising, bad chemical reactivity in battery components previously considered compatible.

Changing the Surroundings Improves Catalysis

Water changes how cobalt-based molecule turns carbon dioxide into chemical feedstock.

How to Draw a Line Narrower Than a Cold Virus

Scientists use ion beams to write high-purity metal structures, enabling nanofabrication opportunities.

Powering Up With a Smart Window

Window material repeatedly switches from being see-through to blocking the heat and converting sunlight into electricity.


Spotlight

Monday June 18, 2018, 09:55 AM

Creating STEM Knowledge and Innovations to Solve Global Issues Like Water, Food, and Energy

Illinois Mathematics and Science Academy (IMSA)

Friday June 15, 2018, 10:00 AM

Professor Emily Liu Receives $1.8 Million DoE Award for Solar Power Systems Research

Rensselaer Polytechnic Institute (RPI)

Thursday June 07, 2018, 03:05 PM

Celebrating 40 years of empowerment in science

Argonne National Laboratory

Monday May 07, 2018, 10:30 AM

Introducing Graduate Students Across the Globe to Photon Science

Brookhaven National Laboratory

Wednesday May 02, 2018, 04:05 PM

Students from Massachusetts and Washington Win DOE's 28th National Science Bowl(r)

Department of Energy, Office of Science

Thursday April 12, 2018, 07:05 PM

The Race for Young Scientific Minds

Argonne National Laboratory

Wednesday March 14, 2018, 02:05 PM

Q&A: Al Ashley Reflects on His Efforts to Diversify SLAC and Beyond

SLAC National Accelerator Laboratory

Thursday February 15, 2018, 12:05 PM

Insights on Innovation in Energy, Humanitarian Aid Highlight UVA Darden's Net Impact Week

University of Virginia Darden School of Business

Friday February 09, 2018, 11:05 AM

Ivy League Graduate, Writer and Activist with Dyslexia Visits CSUCI to Reframe the Concept of Learning Disabilities

California State University, Channel Islands

Wednesday January 17, 2018, 12:05 PM

Photographer Adam Nadel Selected as Fermilab's New Artist-in-Residence for 2018

Fermi National Accelerator Laboratory (Fermilab)

Wednesday January 17, 2018, 12:05 PM

Fermilab Computing Partners with Argonne, Local Schools for Hour of Code

Fermi National Accelerator Laboratory (Fermilab)

Wednesday December 20, 2017, 01:05 PM

Q&A: Sam Webb Teaches X-Ray Science from a Remote Classroom

SLAC National Accelerator Laboratory

Monday December 18, 2017, 01:05 PM

The Future of Today's Electric Power Systems

Rensselaer Polytechnic Institute (RPI)

Monday December 18, 2017, 12:05 PM

Supporting the Development of Offshore Wind Power Plants

Rensselaer Polytechnic Institute (RPI)

Tuesday October 03, 2017, 01:05 PM

Stairway to Science

Argonne National Laboratory

Thursday September 28, 2017, 12:05 PM

After-School Energy Rush

Argonne National Laboratory

Thursday September 28, 2017, 10:05 AM

Bringing Diversity Into Computational Science Through Student Outreach

Brookhaven National Laboratory

Thursday September 21, 2017, 03:05 PM

From Science to Finance: SLAC Summer Interns Forge New Paths in STEM

SLAC National Accelerator Laboratory

Thursday September 07, 2017, 02:05 PM

Students Discuss 'Cosmic Opportunities' at 45th Annual SLAC Summer Institute

SLAC National Accelerator Laboratory

Thursday August 31, 2017, 05:05 PM

Binghamton University Opens $70 Million Smart Energy Building

Binghamton University, State University of New York

Wednesday August 23, 2017, 05:05 PM

Widening Horizons for High Schoolers with Code

Argonne National Laboratory

Saturday May 20, 2017, 12:05 PM

Rensselaer Polytechnic Institute Graduates Urged to Embrace Change at 211th Commencement

Rensselaer Polytechnic Institute (RPI)

Monday May 15, 2017, 01:05 PM

ORNL, University of Tennessee Launch New Doctoral Program in Data Science

Oak Ridge National Laboratory

Friday April 07, 2017, 11:05 AM

Champions in Science: Profile of Jonathan Kirzner

Department of Energy, Office of Science

Wednesday April 05, 2017, 12:05 PM

High-Schooler Solves College-Level Security Puzzle From Argonne, Sparks Interest in Career

Argonne National Laboratory

Tuesday March 28, 2017, 12:05 PM

Champions in Science: Profile of Jenica Jacobi

Department of Energy, Office of Science

Friday March 24, 2017, 10:40 AM

Great Neck South High School Wins Regional Science Bowl at Brookhaven Lab

Brookhaven National Laboratory

Wednesday February 15, 2017, 04:05 PM

Middle Schoolers Test Their Knowledge at Science Bowl Competition

Argonne National Laboratory

Friday January 27, 2017, 04:00 PM

Haslam Visits ORNL to Highlight State's Role in Discovering Tennessine

Oak Ridge National Laboratory

Tuesday November 08, 2016, 12:05 PM

Internship Program Helps Foster Development of Future Nuclear Scientists

Oak Ridge National Laboratory

Friday May 13, 2016, 04:05 PM

More Than 12,000 Explore Jefferson Lab During April 30 Open House

Thomas Jefferson National Accelerator Facility

Monday April 25, 2016, 05:05 PM

Giving Back to National Science Bowl

Ames Laboratory

Friday March 25, 2016, 12:05 PM

NMSU Undergrad Tackles 3D Particle Scattering Animations After Receiving JSA Research Assistantship

Thomas Jefferson National Accelerator Facility

Tuesday February 02, 2016, 10:05 AM

Shannon Greco: A Self-Described "STEM Education Zealot"

Princeton Plasma Physics Laboratory

Monday November 16, 2015, 04:05 PM

Rare Earths for Life: An 85th Birthday Visit with Mr. Rare Earth

Ames Laboratory

Tuesday October 20, 2015, 01:05 PM

Meet Robert Palomino: 'Give Everything a Shot!'

Brookhaven National Laboratory

Tuesday April 22, 2014, 11:30 AM

University of Utah Makes Solar Accessible

University of Utah

Wednesday March 06, 2013, 03:40 PM

Student Innovator at Rensselaer Polytechnic Institute Seeks Brighter, Smarter, and More Efficient LEDs

Rensselaer Polytechnic Institute (RPI)

Friday November 16, 2012, 10:00 AM

Texas Tech Energy Commerce Students, Community Light up Tent City

Texas Tech University

Wednesday November 23, 2011, 10:45 AM

Don't Get 'Frosted' Over Heating Your Home This Winter

Temple University

Wednesday July 06, 2011, 06:00 PM

New Research Center To Tackle Critical Challenges Related to Aircraft Design, Wind Energy, Smart Buildings

Rensselaer Polytechnic Institute (RPI)

Friday April 22, 2011, 09:00 AM

First Polymer Solar-Thermal Device Heats Home, Saves Money

Wake Forest University

Friday April 15, 2011, 12:25 PM

Like Superman, American University Will Get Its Energy from the Sun

American University

Thursday February 10, 2011, 05:00 PM

ARRA Grant to Help Fund Seminary Building Green Roof

University of Chicago

Tuesday December 07, 2010, 05:00 PM

UC San Diego Installing 2.8 Megawatt Fuel Cell to Anchor Energy Innovation Park

University of California San Diego

Monday November 01, 2010, 12:50 PM

Rensselaer Smart Lighting Engineering Research Center Announces First Deployment of New Technology on Campus

Rensselaer Polytechnic Institute (RPI)

Friday September 10, 2010, 12:40 PM

Ithaca College Will Host Regional Clean Energy Summit

Ithaca College

Tuesday July 27, 2010, 10:30 AM

Texas Governor Announces $8.4 Million Award to Create Renewable Energy Institute

Texas Tech University





Showing results

0-4 Of 2215