The simulations are the largest particle-in-cell (PIC) code simulations by number of cores ever performed. PIC simulations are used extensively in plasma physics to model the motion of the charged particles, and the electromagnetic interactions between them, that make up ionized matter. High performance computers such as Sequoia enable these codes to follow the simultaneous evolution of tens of billions to trillions of individual particles in highly complex systems.
OSIRIS simulation on Sequoia of the interaction of a fast-ignition-scale laser with a dense DT plasma. The laser field is shown in green, the blue arrows illustrate the magnetic field lines at the plasma interface and the red/yellow spheres are the laser-accelerated electrons that will heat and ignite the fuel.
Frederico Fiuza, a physicist and Lawrence Fellow at LLNL, performed the simulations in order to study the interaction of ultra-powerful lasers with dense plasmas in a proposed method to produce fusion energy, the energy source that powers the sun, in a laboratory setting. The method, known as fast ignition, uses lasers capable of delivering more than a petawatt of power (a million billion watts) in a fraction of a billionth of a second to heat compressed deuterium and tritium (DT) fuel to temperatures exceeding the 50 million degrees Celsius needed to initiate fusion reactions and release net energy. The project is part of the U.S. Department of Energy's Office of Fusion Energy Science Program.
This method differs from the approach being taken by LLNL's National Ignition Facility to achieve thermonuclear ignition and burn. NIF's approach is called the "central hot spot" scenario, which relies on simultaneous compression and ignition of a spherical fuel capsule in an implosion, much like in a diesel engine. Fast ignition uses the same hardware as the hot spot approach but adds a high-intensity, ultrashort-pulse laser as the "spark" that achieves ignition.
The code used in these simulations was OSIRIS, a PIC code that has been developed over more than 10 years in a collaboration between the University of California, Los Angeles and Portugal's Instituto Superior Técnico. Using this code, Fiuza demonstrated excellent scaling in parallel performance of OSIRIS to the full 1.6 million cores of Sequoia. By increasing the number of cores for a relatively small problem of fixed size, what computer scientists call "strong scaling," OSIRIS obtained 75 percent efficiency on the full machine. But when the total problem size was increased, what is called "weak scaling," a 97 percent efficiency was achieved.
"This means that a simulation that would take an entire year to perform on a medium-size cluster of 4,000 cores can be performed in a single day. Alternatively, problems 400 times greater in size can be simulated in the same amount of time," Fiuza said. "The combination of this unique supercomputer and this highly efficient and scalable code is allowing for transformative research."
OSIRIS is routinely used for fundamental science during the test phase of Sequoia in simulations with up to 256,000 cores. These simulations are allowing researchers, for the first time, to model the interaction of realistic fast-ignition-scale lasers with dense plasmas in three dimensions with sufficient speed to explore a large parameter space and optimize the design for ignition. Each simulation evolves the dynamics of more than 100 billion particles for more than 100,000 computational time steps. This is approximately an order of magnitude larger than the previous largest simulations of fast ignition.
Sequoia is a National Nuclear Security Administration (NNSA) machine, developed and fielded as part of NNSA's Advanced Simulation and Computing (ASC) program. Sequoia is preparing to move to classified computing in support of stockpile stewardship.
"This historic calculation is an impressive demonstration of the power of high-performance computing to advance our scientific understanding of complex systems," said Bill Goldstein, LLNL's deputy director for Science and Technology. "With simulations like this, we can help transform the outlook for laboratory fusion as a tool for science, energy and stewardship of the nuclear stockpile."
Founded in 1952, Lawrence Livermore National Laboratory provides solutions to our nation's most important national security challenges through innovative science, engineering and technology. Lawrence Livermore National Laboratory is managed by Lawrence Livermore National Security, LLC for the U.S. Department of Energy's National Nuclear Security Administration.
Breanna Bishop | EurekAlert!
Terahertz spectroscopy goes nano
20.10.2017 | Brown University
New software speeds origami structure designs
12.10.2017 | Georgia Institute of Technology
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research