‘Iron Sun’ is not a rock band, Sandia researchers find
by Neal Singer
Working at temperatures matching the interior of the sun, researchers at Sandia’s Z machine have been able to determine experimentally, for the first time in history, iron’s role in inhibiting energy transmission from the center of the sun to near the edge of its radiative band.
Because that role is much greater than formerly surmised, the new, experimentally derived amount of iron’s opacity — essentially, its capacity for hindering the transport of radiative energy originating in nuclear fusion reactions deep in the sun’s interior — helps close a theoretical gap for a theory called the Standard Solar Model, widely used by astrophysicists as a foundation to model the behavior of stars.
“Our data, when inserted into the theoretical model, bring its predictions more closely into alignment with physical observations,” says lead investigator Jim Bailey (1683). His team’s work appeared Jan. 1 in the journal Nature.
The gap between the model and observations appeared in 2000 when analysis of spectra emerging from the sun lowered the estimated amount of energy-absorbing elements such as oxygen, nitrogen, and carbon by 30 to 50 percent. The decreased abundances meant that, plugged into the model, energy would arrive at the sun’s radiative edge more readily than before. This created a discrepancy between the star’s theoretical and measured structure. (Structure here refers to the sun’s varying temperatures and densities at different spatial locations.)
What was needed to reestablish the model agreement with observations was a way to balance the decrease in resistance to radiation transport caused by the lowered amounts of some elements.
Jim’s experimental group, including Taisuke Nagayama, Guillaume Loisel, and Greg Rochau (all 1683), in painstaking experiments spanning a 10-year period, discovered that the worldwide astrophysical estimate of the wavelength-dependent opacity of iron should be increased between 30 to 400 percent. The variation does not represent a large uncertainty but merely that iron’s opacity varies with the wavelength of the radiation.
“This represents roughly half the change in the mean opacity needed to resolve the solar problem, even though iron is only one of many elements that contribute,” the authors write in their paper.
One of the most mysterious places in the universe
Previous difficulties in getting accurate data has been that “the inside of a star is one of the most mysterious places in the universe," Jim says. "It’s too opaque for distant instruments to see inside and analyze reactions within it, and too hot to send a probe into it. It has also been too difficult to run tests under appropriate conditions in a laboratory. So the physics that describes how atoms, embedded in solar plasma, absorb radiation, has never been experimentally tested. Yet that process dominates the way energy generated by nuclear reactions in the sun’s interior is transported to the outside.
“Fortunately, in our Z experiments, we can create temperature and density conditions nearly the same as the region inside the sun that affects the discrepancy the most — the edge of the zone where radiative energy transport dominates — in a sample that’s big enough, lasts long enough, and is uniform enough to test. We used that new capability to measure the opacity of iron, one of a few elements that plays the most important part in radiative energy transfer.”
Iron is important because it maintains the highest number of bound electrons that are essential in radiative energy transfer of any element abundant in the sun.
Still, the upward revision of opacities as a solution is bound to be controversial.
“No matter what we do, we can’t make measurements at all the different conditions we need to know,” team member Taisuke says. “There are 20 elements present, and a large range of temperatures and densities. We study iron because its complex electronic structure is a challenge to represent in opacity theories. And it is important in solar physics. The sun is a test bed to model other stars. Without experimental tests we don’t know if these models are accurate. To the extent we fail to understand the sun, then the workings of other stars are subject to some uncertainty.”
The target design of the experiments most recently involves intermingled iron and magnesium, tamped by plastic and beryllium layers on both sides. Radiation streaming through the sample heats up the iron and magnesium, which expand. The plastic restrains the expansion to keep it more uniform for opacity measurements. Magnesium provides information about corresponding density and temperature.
As for Jim, he often can be found by the business end of Sandia's Z machine, which creates the temperature of the sun’s interior — about 2.1 million degrees —in a target about the size of a grain of sand.
From that small sample, Jim is able to do what theorists cannot: He can hold tangible evidence for the way iron atoms behave inside stars in his hand.
The work was sponsored by NNSA and the DOE Office of Science.
-- Neal Singer
Linde, Sandia partner to expand hydrogen fueling network
by Mike Janes
Sandia and industrial gas giant Linde LLC have signed an umbrella cooperative research and development agreement (CRADA) that is expected to accelerate the development of low-carbon energy and industrial technologies, beginning with hydrogen and fuel cells.
The CRADA will kick off with two new research and development projects to accelerate the expansion of hydrogen fueling stations to continue to support the market growth of fuel cell electric vehicles proliferating among the major auto manufacturers. On Nov. 17, Toyota became the latest to unveil a fuel cell electric vehicle.
Last week, Linde opened the first-ever, fully certified commercial hydrogen fueling station near Sacramento with support from the California Energy Commission.
Kickoff projects will help increase H2 fuel station openings
A recent Sandia study, funded by DOE’s Fuel Cell Technologies Office in the Office of Energy Efficiency and Renewable Energy (EERE), determined that 18 percent of fueling station sites in high-priority areas can readily accept hydrogen fueling systems using existing building codes.
The development of meaningful, science-based fire codes and determinations, such as those found in that study, shows that focusing on scientific, risk-informed approaches can reduce uncertainty and help to avoid overly conservative restrictions to commercial hydrogen fuel installations.
Continuing down this path, the first project in the Sandia/Linde CRADA will demonstrate a hydrogen fuel station that uses a performance-based design approach allowable under the National Fire Protection Association hydrogen technologies code, NFPA 2. The project will include support from DOE.
California’s Alternative and Renewable Fuel and Vehicle Technology Program states that Linde expects to open new fueling stations in late 2015.
NFPA 2 provides fundamental safeguards for the generation, installation, storage, piping, use, and handling of hydrogen in compressed gas or cryogenic (low temperature) liquid form and is referenced by many fire officials in the permitting process for hydrogen fueling stations.
“Sections of NFPA 2 are typically not utilized by station developers, as they instead have focused more on rigid distance requirements for fuel dispensers, air intakes, tanks, storage equipment, and other infrastructure,” says Sandia risk expert and fire protection engineer Chris LaFleur (6231).
“We know we can get hydrogen systems into more existing fueling facilities if our risk analyses show how they meet the code,” she says. “This will help boost the developing fuel-cell electric vehicle market significantly.”
The project, Chris adds, will provide a foundation for the hydrogen fueling industry to implement the performance-based approach to station design and permitting, leading to sustained expansion of the hydrogen fueling network. The pilot demonstration, she says, will provide clear evidence that a performance-based design is feasible.
Infrastructure, safety the focus of second project
“Linde’s business interests in building and operating more hydrogen fueling stations for retail use align perfectly with our research goals aimed at accelerating clean and efficient energy technologies into the marketplace,” says Chris San Marchi (8367), lead researcher in Sandia’s hydrogen safety, codes, and standards program.
“We expect our investment with Sandia will lead to a broader consortium of other commercial partners,” says Nitin Natesan, business development manager at Linde. “We’re happy to lead the way for industry, but ultimately we need others on board to join the effort to address barriers to entry of hydrogen fueling infrastructure.”
The second project taking place under the new CRADA focuses on safety aspects of the NFPA code and entails modeling a liquid hydrogen release.
“With Linde’s help, we’re developing a science-based approach for updating and improving the separation distances requirements for liquid hydrogen storage at fueling stations,” says Chris LaFleur. Previous work only examined separation distances for gaseous hydrogen, she says, so validation experiments will now be done on the liquid model.
Sandia’s Combustion Research Facility, for years considered a pre-eminent facility for studying hydrogen behavior and its effects on materials and engines, is a key element of the research.
This focus on improving the understanding of liquid hydrogen storage systems, Chris LaFleur says, will result in more meaningful, science-based codes that will ensure the continued expansion of safe and available hydrogen fuel to meet fuel cell electric vehicle demands.
This work is aligned with Hydrogen Fueling Infrastructure Research and Station Technology (H2FIRST), an EERE project established earlier this year, and builds on over a decade of DOE investments in developing meaningful codes and standards to accelerate hydrogen and fuel cell markets in the US.-- Mike Janes
Sandia was a pioneer in the dawn of a new, diverse workforce
by Nancy Salem
Sandia played a key role in the early years of the affirmative action and equal employment movements as one of the first organizations to sign on to the Plans for Progress (PfP), a program created by US employers to end discrimination and build job opportunities for minorities.
“Sandia has been exceptional in its efforts to recruit and hire African Americans and other minorities,” says Ken Holley (35553), who joined the Labs in 1985 and devoted much of his career to recruiting. “We’ve been willing to hire the talent we helped produce through the early minority programs. To do what we have done to increase the number of minorities with graduate degrees in engineering and science is remarkable for a national laboratory. It was not easy, but Sandia was willing to push against the external and internal challenges. I’m very proud to have been part of it.”
The earliest record of a non-discrimination policy at Sandia Corp., then operated by Western Electric Co. for the US Atomic Energy Commission (AEC), came in a Jan. 25, 1951, letter. It read, “The management of Sandia Corporation has always made a sincere effort to select the best qualified candidate for each vacancy without regard to race, color, or creed. In the future, we will certainly continue to observe this policy and will make sure that no group is treated unfairly.”
A July 15, 1954, letter to Sandia holds the first reference to the policy being a requirement of AEC contractors: “The policy of the United States Government is to promote equal employment opportunity for all qualified persons seeking employment or employed in connection with government contracts.” It continued that contractors will “not discriminate against any employee or applicant for employment because of race, creed, color, or national origin.”
In 1961, President John F. Kennedy issued an executive order requiring that provisions of non-discrimination in employment be included in all new government contracts. The order included the first use of the term “affirmative action” to achieve non-discrimination. Around the same time, Western Electric became one of the original companies to join the PfP. Sandia moved from a policy of non-discrimination to one of affirmative action to address inequality. Sandia’s Plans for Progress was signed by Labs Director Sigmund Schwartz and President Lyndon Johnson in 1964 and announced to the workforce in the Oct. 9, 1964, Lab News.
A range of programs
Sandia and other PfP companies adopted a wide range of programs covering the recruitment, hiring, training, and promotion of African Americans and other minorities. A Sandia memo read, “In the area of affirmative action it has been said that advancing basic human rights to the full potential of our nation’s human resources capability even with the full cooperation of American business and industry will take many years. The problem is so great, so complex, so involved, and has been with us so long that change will be necessary for many years to come.”
Sandia went on to launch a variety of equal employment — a concept that became part of the Civil Rights Act of 1964 — and affirmative action activities including opening the Labs to tours by minority leaders, attending state and national conferences, organizing youth opportunity programs, and participating in community-based vocational guidance and training. Labs officials met with representatives of Bernalillo County, Job Corps, Manpower Development Training, and minority organizations to seek job candidates.
Ivory Alexander, manager of Network Centric Security System Design Dept. 6523, says among the most successful programs was One Year on Campus (OYOC), which allowed the Labs to recruit minorities with bachelor’s degrees, send them for a master’s, then bring them back as members of the technical staff. Ivory was recruited from Michigan State in 1974 and earned a master’s in electrical engineering from Stanford in 1975.
“OYOC, which evolved into the Master’s Fellowship Program and opened to more people, was exclusively for minority candidates at that time,” he says. “It was very attractive to me. I had a similar offer from Bell Labs but figured I’d give this place in the desert a try. That was 40 years ago.”
He says OYOC brought a large influx of African Americans to Sandia in the 1970s. “There was a small group of African American employees in the early 1970s who met with the Lab president about increasing the opportunities for African Americans at Sandia. That occurred in parallel with affirmative action policies being put in place. I was in the right place at the right time.”
Ivory recruited for Sandia the first 20 years of his career. The Labs had a list of Historically Black Colleges and Universities (HBCUs) where it focused recruiting efforts. HBCUs were established in the US in the mid-1800s to give African Americans access to higher education during the time of racial segregation. Sandia developed recruiting relationships with Prairie View A&M University in Texas, North Carolina A&T University, Howard University, and Tennessee State University.
Ivory says the Black Outreach Committee, now called the Black Leadership Committee, formed and helped recruits understand the Sandia culture. “While it wasn’t always easy in the early days to build a career at Sandia as an African American, the Labs environment has changed over time and a recognition exists today that the benefits of and contributions by a diverse workforce enable Sandia to fulfill its mission,” he says.
Lessons to learn
Shortly after joining Sandia, Ken became chairman of the Black Outreach Committee. He also headed up HBCU recruiting, which brought more African Americans to the Labs in the 1980s. “We hired a lot of talented students who have been here now over 20 years,” he says.
But there were lessons to learn. The first was that African Americans needed more than just a primer on Sandia to form a lasting bond. “We thought all we had to do was put in a program and people would come,” Ken says. “But coming to New Mexico for an African American was like going to the moon. We learned we had to develop social mentors in addition to technical mentors, or else they would come and leave and never come back.”
Mentors showed the students where to live, shop, and socialize, and how to get around town. “This was right after the Civil Rights Act, so many of these kids were the first in their families to go to college, and we were grabbing them right then,” Ken says. “A lot of them didn’t have cars. We learned that the technical part didn’t mean as much if you didn’t have a life. Mentorship brought them back, and kept them coming.”
Sandia was involved in other minority recruitment programs including the National Physical Sciences Consortium (NPSC), the National Consortium for Graduate Degrees for Minorities in Engineering and Science (GEM), and the Science and Technology Alliance.
“We used whatever program was necessary at the time to make it work. In the early years we were an unknown entity. The kids on campus knew about Los Alamos because of the history of the atomic bomb, but not Sandia. We had a job to do,” Ken says. “About 25 Sandians recruited at the HBCUs in the early days and brought dozens of African Americans to the Labs. We were hiring into the OYOC program every year. It was a fascinating time.”
Ivory says the years following the launch of affirmative action and equal opportunity were compelling at Sandia and set the stage for continuing efforts to build a diverse workforce.
“There was corporate buy-in and we built a reputation for diversity,” he says. “I’ve been technically challenged and it’s been enjoyable. If I had the chance to do it again, I would.”-- Nancy Salem