Sophisticated features may influence eventual Z-machine rebuild
A new Sandia National Laboratories accelerator called Thor is expected to be 40 times more efficient than Sandia's Z machine, the world's largest and most powerful pulsed-power accelerator, in generating pressures to study materials under extreme conditions.
"Thor's magnetic field will reach about one million atmospheres, about the pressures at Earth's core," said David Reisman, lead theoretical physicist of the project.
Though unable to match Z's 5 million atmospheres, the completed Thor will be smaller -- 2,000 rather than 10,000 square feet -- and will be considerably more efficient due to design improvements that use hundreds of small capacitors instead of Z's few large ones.
Remarkable structural transformation
This change resembles the transformation of computer architecture in which a single extremely powerful computer chip was replaced with many relatively simple chips working in unison, or to the evolution from several high-voltage vacuum tubes to computers powered by a much larger number of low-voltage solid-state switches.
A major benefit in efficiency is that while Z's elephant-sized capacitors require large switches to shorten the machine's electrical pulse from a microsecond to 100 nanoseconds, with its attendant greater impact, the small switches that service Thor's capacitors discharge current in a 100-nanosecond pulse immediately, eliminating energy losses inevitable when compressing a long pulse.
The new architecture also allows finer control of the pulse sent to probe materials.
Toward a more perfect pulse shape
Said Reisman, "Individual cables from pairs of capacitors separate our signals. By combining these signals in any manner we choose, we can tailor very precise pulses of electrical current."
Tailored pulse shapes are needed to avoid shocks that would force materials being investigated to change state. "We want the material to stay in its solid state as we pass it through increasing pressures," he said. "If we shock the material, it becomes a hot liquid and doesn't give us information."
Another advantage for Thor in such testing is that each capacitor's transit time can be not only controlled to the nanosecond level but isolated from the other capacitors. "In 30 seconds on a computer, we can determine the shape of the pulse that will produce a desired compression curve, whereas it takes days to determine how to create the ideal pulse shape for a Z experiment," Reisman said.
Furthermore, because Thor can fire so frequently -- less hardware damage per shot requires fewer technicians and enables more rapid rebooting -- researchers will have many more opportunities to test an idea, he said.
But there's more at stake than extra experiments or even new diagnostics. There's testing the efficiency of a radically different accelerator design.
Thor's shoebox-sized units, known as "bricks," contain two capacitors and a switch. The assembled unit is a fourth-generation descendant of a device jointly developed by Sandia and the Institute of High-Current Electronics in Tomsk, Russia, called a linear transformer driver (LTD). The original LTD units, also called "bricks," had no cables to separate outputs, but instead were linked together to add voltage as well as current. (Because Thor's bricks are isolated from each other, they add current but not voltage.)
Everything depends upon adding bricks. Sandia is building Thor in stages and already has assembled materials. Two intermediate stages are expected in 2016. These will comprise 24 bricks (Thor 24) and 48 bricks (Thor 48). "These are 'first-light' machines that will be used for initial experiments and validation," Reisman said.
Thor 144, when completed, should reach 1 million atmospheres of pressure.
Sandia manager Bill Stygar said more powerful LTD versions of Z ultimately could bring about thermonuclear ignition and even high-yield fusion.
Ignition would be achieved when the fusion target driven by the machine releases more energy in fusion than the electrical energy delivered by the machine to the target. High yield would be achieved when the fusion energy released exceeds the energy initially stored by the machine's capacitors.
A paper published Sept. 9, in Physical Review Special Topics - Accelerators and Beams, co-authored by Reisman, lead electrical engineer Brian Stoltzfus, Stygar, lead mechanical engineer Kevin Austin and colleagues, outlined Sandia's plan for Thor. A Nov. 30 paper, led by Stygar in the same journal, discusses the possibility of building next-generation LTD-powered accelerators to achieve ignition and high-yield fusion.
The academic community also is interested in Thor's architecture. "Part of the motivation for Thor was to develop affordable and compact machines that could be operated at universities," said Reisman. Institutions that have expressed interest include Cornell University, University of California San Diego, Imperial College London and the Carnegie Institution.
Thor's theoretical design was supported by Sandia's Laboratory Directed Research and Development office; later engineering details and hardware were supported by the National Nuclear Security Administration's Science Campaign.
Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corp., for the U.S. Department of Energy's National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies and economic competitiveness
Neal Singer | EurekAlert!
Studying fundamental particles in materials
17.01.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie
Seeing the quantum future... literally
16.01.2017 | University of Sydney
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Materials Sciences
17.01.2017 | Architecture and Construction