NSF TOUTS USE OF SUPERCOMPUTER AND RESOUCES TO HELP PLASMA DYNAMIC RESEARCH

FROM:  NATIONAL SCIENCE FOUNDATION 
A deep dive into plasma
Renowned physicist uses NSF-supported supercomputer and visualization resources to gain insight into plasma dynamic

Studying the intricacies and mysteries of the sun is physicist Wendell Horton life's work. A widely known authority on plasma physics, his study of the high temperature gases on the sun, or plasma, consistently leads him around the world to work on a diverse range of projects that have great impact.

Fusion energy is one such key scientific issue that Horton is investigating and one that has intrigued researchers for decades.

"Fusion energy involves the same thermonuclear reactions that take place on the sun," Horton said. "Fusing two isotopes of hydrogen to create helium releases a tremendous amount of energy--10 times greater than that of nuclear fission."

It's no secret that the demand for energy around the world is outpacing the supply. Fusion energy has tremendous potential. However, harnessing the power of the sun for this burgeoning energy source requires extensive work.

Through the Institute for Fusion Studies at The University of Texas at Austin, Horton collaborates with researchers at ITER, a fusion lab in France and the National Institute for Fusion Science in Japan to address these challenges. At ITER, Horton is working with researchers to build the world's largest tokamak--the device that is leading the way to produce fusion energy in the laboratory.

"Inside the tokamak, we inject 10 to 100 megawatts of power to recreate the conditions of burning hydrogen as it occurs in the sun," Horton said. "Our challenge is confining the plasma, since temperatures are up to 10 times hotter than the center of the sun inside the machine."

Perfecting the design of the tokamak is essential to producing fusion energy, and since it is not fully developed, Horton performs supercomputer simulations on the Stampede supercomputer at the Texas Advanced Computing Center (TACC) to model plasma flow and turbulence inside the device.

"Simulations give us information about plasma in three dimensions and in time, so that we are able to see details beyond what we would get with analytic theory and probes and high-tech diagnostic measurements," Horton said.

The simulations also give researchers a more holistic picture of what is needed to improve the tokamak design. Comparing simulations with fusion experiments in nuclear labs around the world helps Horton and other researchers move even closer to this breakthrough energy source.

Plasma in the ionosphere

Because the mathematical theories used to understand fusion reactions have numerous applications, Horton is also investigating space plasma physics, which has important implications in GPS communications.

GPS signaling, a complex form of communication, relies on signal transmission from satellites in space, through the ionosphere, to GPS devices located on Earth.

"The ionosphere is a layer of the atmosphere that is subject to solar radiation," Horton explained. "Due to the sun's high-energy solar radiation plasma wind, nitrogen and oxygen atoms are ionized, or stripped of their electrons, creating plasma gas."

These plasma structures can scatter signals sent between global navigation satellites and ground-based receivers resulting in a "loss-of-lock" and large errors in the data used for navigational systems.

Most people who use GPS navigation have experienced "loss-of-lock," or instance of system inaccuracy. Although this usually results in a minor inconvenience for the casual GPS user, it can be devastating for emergency response teams in disaster situations or where issues of national security are concerned.

To better understand how plasma in the ionosphere scatters signals and affects GPS communications, Horton is modeling plasma turbulence as it occurs in the ionosphere on Stampede. He is also sharing this knowledge with research institutions in the United States and abroad including the UT Space and Geophysics Laboratory.

Seeing is believing

Although Horton is a long-time TACC partner and Stampede user, he only recently began using TACC's visualization resources to gain deeper insight into plasma dynamics.

"After partnering with TACC for nearly 10 years, Horton inquired about creating visualizations of his research," said Greg Foss, TACC Research Scientist Associate. "I teamed up with TACC research scientist, Anne Bowen, to develop visualizations from the myriad of data Horton accumulated on plasmas."

Since plasma behaves similarly inside of a fusion-generating tokamak and in the ionosphere, Foss and Bowen developed visualizations representing generalized plasma turbulence. The team used Maverick, TACC's interactive visualization and data analysis system to create the visualizations, allowing Horton to see the full 3-D structure and dynamics of plasma for the first time in his 40-year career.

"It was very exciting and revealing to see how complex these plasma structures really are," said Horton. "I also began to appreciate how the measurements we get from laboratory diagnostics are not adequate enough to give us an understanding of the full three-dimensional plasma structure."

Word of the plasma visualizations soon spread and Horton received requests from physics researchers in Brazil and researchers at AMU in France to share the visualizations and work to create more. The visualizations were also presented at the XSEDE'14 Visualization Showcase and will be featured at the upcoming SC'14 conference.

Horton plans to continue working with Bowen and Foss to learn even more about these complex plasma structures, allowing him to further disseminate knowledge nationally and internationally, also proving that no matter your experience level, it's never too late to learn something new.

-- Makeda Easter, Texas Advanced Computing Center (
-- Aaron Dubrow, NSF
Investigators
Wendell Horton
Daniel Stanzione
Related Institutions/Organizations
Texas Advanced Computing Center
University of Texas at Austin

RHEA BY DAY

Image Credit: NASA/JPL-Caltech/Space Science Institute.

FROM:  NASA 
Rhea's Day in the Sun

A nearly full Rhea shines in the sunlight in this recent Cassini image. Rhea (949 miles, or 1,527 kilometers across) is Saturn's second largest moon.

Lit terrain seen here is on the Saturn-facing hemisphere of Rhea. North on Rhea is up and rotated 43 degrees to the left. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 10, 2013.

The view was obtained at a distance of approximately 990,000 miles (1.6 million kilometers) from Rhea. Image scale is 6 miles (9 kilometers) per pixel.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

NSF AND THE SUN'S MYSTERIOUS CORONA

Right:  Image Credit: NASA/Solar Dynamics Observatory

FROM:  NATIONAL SCIENCE FOUNDATION
It's hot...super hot
Finding answers around the sun

November 12, 2013

Astronomers have collectively puzzled over two working theories for a conundrum involving the sun that have been discussed in Astronomy 101 classes for decades: Why is the sun's corona (the atmosphere beyond the sun) so hot? The sun's core is a searing 15 million Kelvins, but by the time that heat reaches the sun's surface, it cools off to a mere 6,000 degrees, only to again heat up to more than a million degrees in the corona.

Two National Science Foundation- (NSF) funded researchers at Columbia University recently published what they believe is the solution, and it has to do with magnetic waves known as Alfven waves. The researchers present their findings today at the Hinode 7 Science Meeting in Japan.

Michael Hahn and Daniel Wolf Savin analyzed data from the Extreme Ultraviolet Imaging Spectrometer on the Japanese satellite Hinode over a polar coronal hole and found that, much like the vibrations of a plucked guitar string, the solar magnetic field lines also pulsate, and in doing so transfer energy from below the sun's surface into the corona. Hinode's spectrometer captured the waves penetrating the upper solar atmosphere.

"This is a fundamentally important finding," said Ilia Roussev, NSF program director for solar terrestrial research. "This issue is the holy grail of solar physics. If this allows us to better understand the mechanics, then it has tremendous consequences."

The coronal heating problem has been debated for 70 years with researchers essentially falling into two camps: one involving the Alfven waves and the other attributing the heating "problem" to magnetic field loops that stretch across the solar surface with the potential to "snap" and release energy. The important key to Hahn and Savin's findings comes with Hinode satellite observations. The team has been studying Hinode data since 2009 with funding since 2011 from the NSF Solar, Heliospheric and INterplanetary Environment (SHINE) Program.

"This is the big, unanswered question in solar physics, and nearly everyone in the field is somehow working on trying to solve it," Savin said. "We really had no idea where the research would lead us, but we were hoping to at least be able to add another piece to the puzzle. We did not expect it to be such a big piece."

In fact, technology had to catch up to theory to make this happen. The Hinode satellite, a Japanese mission with the Extreme Ultraviolet Imaging Spectrometer developed as collaboration between Japan, the United Kingdom and the United States, offered unique, previously unattainable observations.

"Until that time, we could only see the sun in white light; we didn't have UV observations. But, now we do," Roussev noted. With the UV capability, researchers can glean information on chemical makeup and physical conditions near the sun's surface that until the mid-1990s could not be observed. Hinode has been studying the sun since 2006.

"Some in the community have responded enthusiastically to our findings; others more cautiously, but that is to be expected," Savin said. "Others, including us, have pointed out that there may not be just one solution to the problem as there are different structures on the Sun. Our work is relevant for coronal holes, which are the source of the fast solar wind. A different mechanism or mechanisms may be operating in the quiet sun."

The "in's and out's" of Earth's atmosphere

While the sun is almost 93 million miles from earth, the electrons and protons from the sun move toward Earth via a wind of particles. This solar wind has impacts on the Earth's atmosphere in locations where satellites provide important imagery of our planet and allow technology like GPS and cell phones to operate.

"Ultimately, this kind of research does provide new perspective on space weather, which is known to affect the Earth" said Hahn, who was awarded a 2012 Blavatnik Award for Young Scientists by the New York Academy of Sciences for his work on the coronal heating problem. "Understanding these fundamental processes improves our understanding, of not just the solar corona, but also of space weather."

Specifically, the high temperature of the sun's corona causes it to emit X-rays that can affect the conditions of Earth's atmosphere where satellites roam. "The sun is the biggest X-ray machine in the solar system," Roussev explained. "The upper layers of earth's atmosphere absorb those X-rays, but what they do is heat that upper atmosphere. It expands almost like the Earth breathing in and out. This has a direct impact on the lifetime of satellites. The more the atmosphere expands, the slower the satellites move. That shortens their lifetime as they slow to a point where they re-enter the atmosphere."

Puzzle solved. Now what?

The interesting thing about potentially solving a puzzle like this one is that the solution raises more questions.

"What causes Alfven waves to be damped at such surprisingly low heights in the corona?" Savin asked, who is now proposing a series of experiments in plasma physics to simulate conditions in a coronal hole and explore possible mechanisms that would cause the waves to lose their energy. "We are also analyzing Hinode observations of other solar structures in the corona to see what role waves play in heating those structures."

Other researchers will likely explore replication, especially involving observations elsewhere in the corona, rather than just polar coronal holes.

"People have been claiming to solve the coronal heating problem for decades," Hahn said. "We are reasonably confident in our results and wait now for others to reproduce our findings."

-- Ivy F. Kupec
Investigators
Michael Hahn
Daniel Wolf Savin
Related Institutions/Organizations
Columbia University
Locations
Columbia University , New York

IRIS TO HELP SCIENTISTS UNDERSTAND SUN'S PHYSICAL PROCESSES



Workers unload NASA's IRIS spacecraft from a truck at the processing facility at Vandenberg where the spacecraft will be readied for launch aboard an Orbital Sciences Pegasus XL rocket. Photo credit: VAFB/Randy Beaudoin

FROM: NASA

NASA’s Interface Region Imaging Spectrograph (IRIS) satellite arrived at Vandenberg Air Force Base in California on Tuesday, April 16, to begin its final preparations for launch currently scheduled no earlier than May 28. IRIS will improve our understanding of how heat and energy move through the deepest levels of the sun’s atmosphere, thereby increasing our ability to forecast space weather. Following final checkouts, the IRIS spacecraft will be placed inside an Orbital Sciences Pegasus rocket. Deployment of the Pegasus from the L-1011 carrier aircraft is targeted for 7:27 p.m. PDT at an altitude of 39,000 feet at a location over the Pacific Ocean about 100 miles northwest of Vandenberg AFB off the central coast of California south of Big Sur.

"IRIS will contribute significantly to our understanding of the interface region between the sun's photosphere and corona," said Joe Davila, IRIS mission scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "This region is crucial for understanding how the corona gets so hot."

IRIS carries a single instrument, a multi-channel imaging spectrograph with an ultraviolet (UV) telescope that will help scientists better understand the physical processes in the sun’s interface region.

"With the high-resolution images from IRIS, scientists will be able to use advanced computer models to unravel how matter, light, and energy move from the sun’s 6,000 Kelvin surface to its million Kelvin corona," said Eric Ianson, IRIS mission manager at NASA Goddard. "Scientists will be able to combine data from NASA’s IRIS and Solar Dynamics Observatory and the NASA/JAXA Hinode missions to obtain a more comprehensive understanding of the sun’s atmosphere."

IRIS is a NASA Small Explorer mission. The program provides frequent flight opportunities for world-class scientific investigations from space using innovative, streamlined and efficient management approaches within the heliophysics and astrophysics areas.

NASA's Launch Services Program at Kennedy Space Center, Fla., is responsible for launch management. Lockheed Martin’s Advanced Technology Center Solar and Astrophysics Laboratory in Palo Alto, Calif., designed and built the IRIS spacecraft and instrument. NASA’s Ames Research Center in Moffett Field, Calif., is responsible for mission operations and ground data systems.

VIDEO: BUBBLES IN THE HELIOSHEATH

FROM: NASA

Sea of Bubbles at Edge of Solar System
This animation summarizes the new heliospheric scenario and the formation of the "sea" of bubbles in the heliosheath. The Sun’s magnetic field points toward the Sun in the Northern hemisphere and away from the Sun in the Southern (shown in red and blue). These oppositely pointing magnetic fields are separated by a layer of current called the heliospheric current sheet. Due to the tilt of the magnetic axis in relation to the axis of rotation of the Sun, the heliospheric current sheet flaps like a flag in the wind. The flapping current sheet separates regions of oppositely pointing magnetic field, called sectors. As the solar wind speed decreases past the termination shock, the sectors squeeze together, bringing regions of opposite magnetic field closer to each other. When the separation of sectors becomes very small, the sectored magnetic field breaks up into a sea of nested "magnetic bubbles" in a phenomenon called magnetic reconnection.

VENUS PASSES BY THE SUN

FROM:  NASA
This image from NASA’s Solar Dynamics Observatory shows Venus as it nears the disk of
The sun on June 5, 2012.  Venus’s 2012 transit will be the last such event until 2117. Photo:  NASA Solar Dynamics Observatory.