On Sept. 17 a team of LLNL physicists led by David Martinez and Jave Kane, in collaboration with the French Alternative Energies and Atomic Energy Commission (CEA) and the University of Maryland, succeeded for the first time in creating “pillar” structures in the laboratory. The structures are relevant to the Eagle Nebula’s Pillars of Creation observed by the Hubble Telescope (left). Two Eagle shots produced very long duration (45- and 60-nanosecond) x-ray drives to induce molecular pillar formation in a foam target (right). Excellent data were obtained on both shots. Pillars credit: NASA/ESA/Hubble Heritage Team (STScI/AURA)/J. Hester, P. Scowen (Arizona State U.)
(Download Image)NIF Efficiencies Boost Discovery Science Experiments
NIF’s ability to conduct groundbreaking Discovery Science (DS) experiments—studies of how the universe works at a fundamental level—has been significantly enhanced by the recent efficiency improvements that now make it possible for NIF to fire an average of a target shot a day.
In one week in September LLNL researchers, in collaboration with several international academic and research institutions, conducted eight highly successful shots in support of four DS experimental campaigns, bringing the total number of DS shots for Fiscal Year 2015 to 44 in eight different experimental campaigns. In all, NIF conducted 356 target shots during the fiscal year, exceeding the goal of 300 shots for FY2015 established by the recent "120-Day Study" of ways to increase the shot rate. This represented an 86 percent increase in target shots over FY2014.
The Discovery Science program on NIF began in 2010 to provide academic users with access to the unique density, temperature, and velocity regimes that NIF can create, and to enhance collaboration between academia and LLNL scientists. The September experiments completed NIF’s first competitively-awarded academic-use campaigns. Nine new DS projects will be initiated in FY2016, and NIF has received 22 proposals for FY2017 DS experiments.
The campaigns completed in September were:
- The Eagle team studied the radiation hydrodynamics of the Eagle Nebula, the famous "Pillars of Creation" molecular cloud in an active star-forming region 7,000 light-years away (see "Unlocking the Secrets of Star Creation").
- The cryogenic equation of state (CryoEOS) team used NIF to study the high-pressure dynamic properties of hydrogen in conditions similar to those in giant gaseous planets (the equation of state is the relationship between the target material’s pressure, density, and temperature). The researchers are exploring the potential of a plasma phase transition in hydrogen under pressures exceeding one megabar (one million times atmospheric pressure).
- The iron EOS (FeEOS) team studied the equation of state of iron at pressures exceeding 10 megabars in studies relevant to the interiors of Earth-like and super-Earth exoplanets.
- The very high pressure (near-gigabar) plasma conditions of plastic (CH), relevant to the interior conditions of white dwarfs (burned-out stars) and brown dwarfs ("almost stars" that never burned), were investigated by the GBar team.
"Being able to probe these extreme conditions experimentally on NIF will have very high impact on our understanding of the planets and stars, including providing insights into which exoplanets might be capable of sustaining life and into the dynamics of how stars are formed," said Bruce Remington, program leader for NIF Discovery Science.
In a recent Physics of Plasmas paper, Remington and two colleagues—Robert Rudd of LLNL and Justin Wark of the University of Oxford in the UK—presented a comprehensive review of the kinds of fundamental science experiments that have been enabled by NIF, the OMEGA Laser System at the University of Rochester, and other high-power lasers, pulsed power facilities, and next-generation light sources.
"Regimes of science hitherto thought out of reach in terrestrial settings are now being accessed routinely," the researchers said. "There are a multitude of new regimes of science that are now accessible in laboratory settings. Matter can now be studied experimentally with precision at very high pressures and over very short time scales.
"With these modern experimental and theoretical capabilities," they said, "the pace of new discoveries in the properties, phases, and states of matter is accelerating, which highlights one of the most exciting eras in science. Coupled with the studies of planetary formation, the formation of planetary systems, and investigations of the likely environments in, on, and around the exoplanets, these new experimental and theoretical capabilities are tied to far-reaching explorations about the universe.
"This is an exciting field," they said, "and an exceptionally exhilarating time to be involved in this area of research."
