A team of scientists working at the U.S. Department of Energy's Princeton Plasma Physics Laboratory (PPPL) has found that increasing the amount of lithium coating in the wall of an experimental fusion reactor greatly improves the ability of experimentalists to contain the hot, ionized gas known as plasma. Adding more lithium also enhances certain plasma properties aiding the reaction, the researchers found.
As more lithium is added (with increasing discharge number in yellow), the plasma light changes from red (from recycling of the deuterium fuel gas) to green (lithium emission from the edge of the plasma) and the overall (recycling) light levels decrease. Credit: Princeton Plasma Physics Laboratory
"The lesson here for confining plasma is surprising and simple: When you use more and more lithium, the plasma confinement gets better and better," said Rajesh Maingi, a physicist from the Oak Ridge National Laboratory (ORNL) who is on long-term assignment to PPPL. "This is not what we expected to see. We thought the effect would taper off at some point. But it doesn't. When it comes to fusion plasmas, it's "the more, the merrier.'"
If plasma energy confinement is improved, a fusion reactor can, in principle, be made smaller and, therefore, cheaper. Energy confinement is a measure of how long (in seconds) power that is injected into the plasma stays in the plasma before leaking out to the walls.
Spraying lithium onto the inner surface of an experimental fusion device at PPPL known as the National Spherical Torus Experiment (NSTX) improves several other conditions for fusion, the experimenters found. The lithium reduced recycling—the problematic ricocheting of particles into the vessel wall and back into the plasma (Figure 1). Recycling leads to cooling, contamination, and, ultimately, dissipation of the energy of the plasma. In addition to reducing recycling, the lithium coating—and enhanced coatings based on it—also enhanced the reaction by decreasing chaotic instabilities both at the plasma's edge, and also on a larger scale.
The experiment's results indicate that fusion machine designers may be able to reduce the size and the level of heating in future devices designed to use lithium coating technologies.
In addition to Maingi, other researchers on the effort included: Stanley Kaye and Charles Skinner from PPPL, D.P. Boyle from Princeton University; and J.M. Canik from ORNL. This work recently appeared in Physical Review Letters 107 (2011) 145004.
The work is being presented at the 53rd Annual Meeting of the American Physical Society Division of Plasma Physics, being held Nov. 14-18, in Salt Lake City, Utah.
Abstracts:BO4.00004 The continuous improvement of H-mode discharge performance with progressively increasing lithium coatings in NSTX
Saralyn Stewart | EurekAlert!
Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University
Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and Technology
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences