Back to Table of contents

Primeur weekly 2018-02-19

Exascale supercomputing

Ready for Exascale: researchers find algorithm for large-scale brain simulations on next-generation supercomputers ...

Quantum computing

Researchers demonstrate promising method for improving quantum information processing ...

Fingerprints of quantum entanglement ...

Focus on Europe

Karel Luyben appointed Dutch National Coordinator for Open Science ...

Middleware

An OLCF-developed visualization tool offers customization and faster rendering ...

Hardware

Dell EMC next generation converged infrastructure makes data centre modernization even simpler ...

Cray reports 2017 full year and fourth quarter financial results ...

Michael Levine and Ralph Roskies Day proclaimed in Pittsburgh and Allegheny County ...

MACH-2 put into operation at 77 trillion operations/second ...

Applications

CENIC recognizes technology projects to combat California wildfires ...

3D-e-Chem team develops building blocks and recipes for computer-aided drug discovery ...

Researchers find blood pressure drug holds promise for preventing onset of Type 1 diabetes ...

NCSA allocates over $2.4 million in new Blue Waters supercomputer awards to Illinois researchers ...

NCSA researchers create one of the most reliable tools for long-term crop prediction in the U.S. Corn Belt ...

Embracing complexity in biological systems ...

Particle interactions calculated on Titan support the search for new physics discoveries ...

GM revs up diesel combustion modeling on Titan supercomputer ...

NEC and Tohoku University succeed in AI-based new material development ...

Physics data processing at NERSC dramatically cuts reconstruction time ...

Advanced computing and water management at the AAAS Meeting 2018 ...

Neural networks everywhere ...

Supermassive black hole model predicts characteristic light signals at cusp of collision ...

New turbulent transport modelling shows multiscale fluctuations in heated plasma ...

TACC and DOD engage in four-year transformational design project ...

The Cloud

Atos signs key contract with the European Space Agency to enable new services with satellite data ...

Oracle buys Zenedge ...

NEC contributes to ecosystem for enhancing virtualized network orchestration ...

New turbulent transport modelling shows multiscale fluctuations in heated plasma

13 Feb 2018 Washington, D.C. - Researchers at the DIII-D National Fusion Facility used a 'reduced physics' fluid model of plasma turbulence to explain unexpected properties of the density profile inside a tokamak experiment. Modelling plasma's turbulent behaviour could help scientists optimize the tokamak performance in future fusion reactors like ITER. They discuss their findings inPhysics of Plasmas.

Applying heat in a tokamak produces many interesting phenomena such as changes in plasma rotation and density. DIII-D researchers modeled how different types of heating, like microwaves that produce electron heating or neutral beams that produce ion heating, influences the plasma density, behaviour of impurities and turbulent transport. The different heating methods drive turbulence at the long (ion) scales and much shorter (electron) scales that are at the frontier of turbulence computer simulations.

Their findings, reported inPhysics of Plasmas, from AIP Publishing, showed that heating the electrons in a fusion reactor caused important changes in density gradients within the plasma. Their "trapped gyro-Landau fluid" (TGLF) model predicted that adding heat excited turbulence, at wavelengths between the ion and electron scales, and would produce a particle pinch that modifies the plasma's overall density profile. Additionally, in this paper, researchers used their reduced transport model to predict impurity transport in a fusion reactor.

Brian Grierson, a Princeton Plasma Physics Laboratory physicist working as a researcher at the DIII-D National Fusion Facility in San Diego, said that "when you heat the plasma, you don't just change the temperature, you change the type of turbulence that exists, and that has secondary implications on the transport of plasma density and the plasma rotation".

Generally, heat flowing from the hot plasma center to the cold plasma edge drives turbulent diffusion, which should act to flatten the density gradient. "But the fascinating thing is that sometimes applying heat in a fusion reactor causes it to produce a density gradient rather than flatten it", Brian Grierson stated. This density peaking is significant because the fusion reaction between deuterium and tritium particles in a tokamak increases as the density of the plasma increases. In other words, he said, "fusion power is proportional to the (plasma) density squared".

Brian Grierson credits Gary Staebler, a co-author on the paper, as the General Atomics theoretician behind TGLF, the model tested in this paper. TGLF is a reduced physics model of the "full physics" gyrokinetic code GYRO for turbulent transport, which must be run on supercomputers. Using this more cost-effective TGLF model, researchers were able to execute the code with various experimental measurement and inputs hundreds of times to quantify how uncertainties in the experimental data affect the theoretical interpretation.

Going forward, Brian Grierson hopes that these findings will help inform research to advance the fusion community's understanding of extremely small-scale fluctuations and impurity transport within a plasma.

"We need to understand transport under ion and electron heating to confidently project to future reactors, because fusion power reactors will have both ion and electron heating", Brian Grierson stated. "This result identifies what we need to investigate with the computationally challenging full physics simulations to verify the interaction of particle, momentum and impurity transport with heating."

The article, " Multi-scale transport in the DIII-D ITER baseline scenario with direct electron heating and projection to ITER ", is authored by B.A. Grierson, Gary Staebler, Wayne M. Solomon, George R. McKee, Christopher Holland, Max E. Austin, Alessandro Marinoni, Lothar Schmitz, Robert I. Pinsker, and the DIII-D Team. The article appeared in the journalPhysics of Plasmas, February 13, 2018.
Source: American Institute of Physics

Back to Table of contents

Primeur weekly 2018-02-19

Exascale supercomputing

Ready for Exascale: researchers find algorithm for large-scale brain simulations on next-generation supercomputers ...

Quantum computing

Researchers demonstrate promising method for improving quantum information processing ...

Fingerprints of quantum entanglement ...

Focus on Europe

Karel Luyben appointed Dutch National Coordinator for Open Science ...

Middleware

An OLCF-developed visualization tool offers customization and faster rendering ...

Hardware

Dell EMC next generation converged infrastructure makes data centre modernization even simpler ...

Cray reports 2017 full year and fourth quarter financial results ...

Michael Levine and Ralph Roskies Day proclaimed in Pittsburgh and Allegheny County ...

MACH-2 put into operation at 77 trillion operations/second ...

Applications

CENIC recognizes technology projects to combat California wildfires ...

3D-e-Chem team develops building blocks and recipes for computer-aided drug discovery ...

Researchers find blood pressure drug holds promise for preventing onset of Type 1 diabetes ...

NCSA allocates over $2.4 million in new Blue Waters supercomputer awards to Illinois researchers ...

NCSA researchers create one of the most reliable tools for long-term crop prediction in the U.S. Corn Belt ...

Embracing complexity in biological systems ...

Particle interactions calculated on Titan support the search for new physics discoveries ...

GM revs up diesel combustion modeling on Titan supercomputer ...

NEC and Tohoku University succeed in AI-based new material development ...

Physics data processing at NERSC dramatically cuts reconstruction time ...

Advanced computing and water management at the AAAS Meeting 2018 ...

Neural networks everywhere ...

Supermassive black hole model predicts characteristic light signals at cusp of collision ...

New turbulent transport modelling shows multiscale fluctuations in heated plasma ...

TACC and DOD engage in four-year transformational design project ...

The Cloud

Atos signs key contract with the European Space Agency to enable new services with satellite data ...

Oracle buys Zenedge ...

NEC contributes to ecosystem for enhancing virtualized network orchestration ...