May 22, 2013
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Solar Cells Get a Boost from Bouncing Light
A new twist on an old solar cell design sends light ricocheting through layers of microscopic spheres, increasing its electricity-generating potential by 26 percent.
By engineering alternating layers of nanometer and micrometer particles, a team of engineers from the University of Minnesota has improved the efficiency of a type of solar cell by as much as 26 percent. These cells, known as dye-sensitized solar cells (DSSC), are made of titanium dioxide (TiO2), a photosensitive material that is less expensive than the more traditional silicon solar cells, which are rapidly approaching the theoretical limit of their efficiency. Current DSSC designs, however, are only about 10 percent efficient.
One reason for this low efficiency is that light from the infrared portion of the spectrum is not easily absorbed in the solar cell. The new layered design, as described in the AIP’s Journal of Renewable and Sustainable Energy, increases the path of the light through the solar cell and converts more of the electromagnetic spectrum into electricity. The cells consist of micrometer-scale spheres with nanometer pores sandwiched between layers of nanoscale particles. The spheres, which are made of TiO2, act like tightly packed bumpers on a pinball machine, causing photons to bounce around before eventually making their way through the cell.
Each time the photon interacts with one of the spheres, a small charge is produced. The interfaces between the layers also help enhance the efficiency by acting like mirrors and keeping the light inside the solar cell where it can be converted to electricity. This strategy to increase light-harvesting efficiency can be easily integrated into current commercial DSSCs.
Electrons and Lattice Vibrations: A Strong Team in the Nano World
Measured two-dimensional spectrum. Without the interaction of the electron with lattice vibrations there would be no signal in the range shown. (Credit: Image courtesy of Forschungsverbund Berlin e.V. (FVB))
Using a newly developed type of spectroscopy, Berlin researchers have shown that electrons in a semiconductor are best described as a cloud with a size of a few nanometer (one nanometer is one billionth of one meter). The cloud size is determined by the interaction of the electron with vibrations in the crystal lattice.
Semiconductor electronics generates, controls, and amplifies electrical current in devices like the transistor. The carriers of the electric current are mobile electrons, which move with high velocities through the crystal lattice of the semiconductor. Doing this, they lose part of their kinetic energy by causing atoms in the lattice to vibrate. In semiconductors like gallium arsenide the positively and negatively charged ions of the crystal lattice vibrate with an extremely short period of 100 fs (1 fs = 10-15 s = 1 billionth part of one millionth of a second). In the microcosm of electrons and ions such vibrations are quantized. This means that the vibrational energy can only be an integer multiple of a vibrational quantum, also known as a phonon. When an electron interacts with the crystal lattice (the so called electron-phonon interaction), energy is transferred from the electron to the lattice in the form of such vibrational quanta.
Berlin researchers report in the latest issue of the scientific journal Physical Review Letters that the strength of the electron-phonon interaction depends sensitively on the electron size, i.e., on the spatial extent of its charge cloud. Experiments in the time range of the lattice vibration show that reducing the electron size leads to an increase of the interaction by up to a factor of 50. This results in a strong coupling of the movements of electrons and ions. Electron and phonon together form a new quasi particle, a polaron.
To visualize this phenomenon, the researchers used a nanostructure made from gallium arsenide and gallium aluminum arsenide, in which the energies of the movements of electrons and ions were tuned to each other. The coupling of both movements was shown by a new optical technique. Several ultrashort light pulses in the infrared excite the system under study. The subsequent emission of light by the moving charge carriers is measured in real time. In this way two-dimensional nonlinear spectra (see Fig.) are generated, which allow the detailed investigation of coupled transitions and the determination of the electron-phonon coupling strength. From the coupling strength one finds the size of the electron cloud, which is just 3-4 nanometers (1 nanometer = 10-9 m = 1 billionth of one meter). Furthermore, this new method shows for the first time the importance of electron-phonon coupling for optical spectra of semiconductors. This is of interest for the development of optoelectronic devices with custom-tailored optical and electric properties.
Solar Energy: Smart Energy Management Systems Help Store Power for Later Use
The concentrating photovoltaic modules in Egypt are precisely aligned to the sun. They supply power to irrigate wheat fields. (Credit: Image courtesy of Fraunhofer-Gesellschaft)
Storing power is complicated and expensive, but very often, especially far away from the regular power grids, there is no way around large batteries for grid-independent electricity consumers. It would make more sense to use the electricity when it is generated. This becomes possible with the help of a smart energy management system.
For fruits, cereals and leguminous plants such as oranges, wheat, beans and olives to grow in hot and dry climates, they must be irrigated regularly. And very often the water used comes from deep wells. In Egypt, many farmers currently use diesel generators to water their fields. A model project in Upper Egypt, in Wadi El Natrun, shows that other methods are possible. Here, a photovoltaic stand-alone system takes care of irrigating a wheat field. Concentrator photovoltaic system (CPV) modules — which, due to their higher degree of effectiveness and their particular construction, require far less space than traditional PV modules — supply the energy, while Fresnel lenses concentrate the rays of the sun onto pinhead-sized multi-junction solar cells.
With the aid of a tracking motor, the CPV cells, which are attached to a pillar, follow the sun precisely to achieve an optimized yield of solar light. They supply the energy for a submersible pump that pumps the water up from a well that is 105 feet deep and for a small desalination unit that satisfies farmers’ potable water requirements. The CPV cells also supply the energy for PV-module trackers, the monitoring and control system and an air-conditioning unit that cools the utility room of the facility.
In order to make the complete system as inexpensive as possible, the developers largely did without expensive batteries for the intermediate storage of the energy gained from the solar cells. “Where there is no public power grid, the PV systems currently operate cost-effectively, due to their low operating costs. The only problems are posed by the high initial costs of the investment, in which the batteries play a substantial role,” explained Jakob Wachtel from the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, Germany.
“By immediately using the largest share of the energy that is generated we can save on expensive storage media capacities,” adds his colleague, Alexander Schies. A sophisticated energy management system monitors the generation of energy and ensures that it immediately goes where it is needed at the moment, such as the submersible pump to fill up the water reservoir, the irrigation pump when it is time to irrigate the field or the desalination unit. Developers only store some of the solar energy in a relatively small battery to operate the CPV tracker and the measuring system. “We need this reserve, in particular, to align the CPV modules in the morning to their morning position,” explained Jakob Wachtel. Unlike traditional solar modules made of silicon, the concentrating photovoltaic systems provide energy only if they are precisely aligned to the sun.
All of the irrigation system components have micro-controllers that transmit their status data to the energy management system that controls them. The Universal Energy Supply Protocol (UESP) developed at the ISE was designed especially for this type of energy and load management and is the form of the communication of choice. Currently, the UESP is being integrated into the CANopen protocol CiA454 of the CiA (CAN in Automation) organization as an application profile for grid-independent energy supply systems. CANopen is rather prevalent in automation technology and has established itself as the standard for the control of electrical devices. “All systems that work with these kinds of protocols can be expanded at any time with devices that ‘understand’ CANopen or UESP — completely independent of the manufacturer. This is practical if a defective component has to be replaced,” emphasized Alexander Schies. This, too, contributes to the savings. At the same time it simplifies the maintenance and further development of the stand-alone CPV system.
New Way to Manage Energy in the Smart Grid
Researchers at the University of Southampton have developed a mechanism which uses smart computerised agents to control energy storage devices in the home, resulting in energy savings of up to 16 per cent.
In a paper entitled Decentralised Control of Micro-Storage in the Smart Grid, which will be delivered at the Twenty-Fifth Conference on Artificial Intelligence (AAAI-11) in San Francisco on August 11, Dr. Thomas Voice describes how he and his colleagues developed a novel decentralised control mechanism to manage micro-storage in the smart grid.
The researchers developed a completely decentralised mechanism which uses agent-based techniques to allow energy suppliers to manage the demand from their consumers, which, in turn, allows them to reduce their wholesale purchasing costs, yielding savings of up to 16 per cent in energy cost for consumers using devices with an average capacity of 10 kWh.
The researchers’ approach involves using a real-time pricing scheme that is broadcast to consumers in advance of each daily period. Computerised agents then buy, sell, and store energy on behalf of the home-owners in order to minimise their net electricity costs. By adjusting the pricing scheme to match the conditions on the wholesale market, the supplier is able to ensure that, as a whole, consumer agents converge to a stable and efficient equilibrium where costs and carbon emissions are minimised.
“In this paper, we propose a novel algorithm for the decentralised control of widespread micro-storage in the smart grid,” said Dr Voice. “We see this as an important step to showing that the adoption of widespread, supplier managed home energy micro-storage is a practical desirable technology to develop for the benefit of both suppliers and consumers. Using the techniques described in this paper, we can envisage energy suppliers providing new tariffs that will incentivise consumers to buy affordable small scale storage devices. In turn this will allow suppliers to manage aggregate load profiles, improve efficiency and reduce carbon output.”
This work as carried out as part of the industrially funded IDEAS project, led by Dr. Alex Rogers and Professor Nick Jennings at the University of Southampton.
Hybrid Solar System Makes Rooftop Hydrogen
This is the hybrid system schematic. (Credit: Nico Hotz)
While roofs across the world sport photovoltaic solar panels to convert sunlight into electricity, a Duke University engineer believes a novel hybrid system can wring even more useful energy out of the sun’s rays.
Instead of systems based on standard solar panels, Duke engineer Nico Hotz proposes a hybrid option in which sunlight heats a combination of water and methanol in a maze of glass tubes on a rooftop. After two catalytic reactions, the system produces hydrogen much more efficiently than current technology without significant impurities. The resulting hydrogen can be stored and used on demand in fuel cells.
For his analysis, Hotz compared the hybrid system to three different technologies in terms of their exergetic performance. Exergy is a way of describing how much of a given quantity of energy can theoretically be converted to useful work.
“The hybrid system achieved exergetic efficiencies of 28.5 percent in the summer and 18.5 percent in the winter, compared to 5 to 15 percent for the conventional systems in the summer, and 2.5 to 5 percent in the winter,” said Hotz, assistant professor of mechanical engineering and materials science at Duke’s Pratt School of Engineering.
The paper describing the results of Hotz’s analysis was named the top paper during the ASME Energy Sustainability Fuel Cell 2011 conference in Washington, D.C. Hotz recently joined the Duke faculty after completing post-graduate work at the University of California-Berkeley, where he analyzed a model of the new system. He is currently constructing one of the systems at Duke to test whether or not the theoretical efficiencies are born out experimentally.
Hotz’s comparisons took place during the months of July and February in order to measure each system’s performance during summer and winter months.
Like other solar-based systems, the hybrid system begins with the collection of sunlight. Then things get different. While the hybrid device might look like a traditional solar collector from the distance, it is actually a series of copper tubes coated with a thin layer of aluminum and aluminum oxide and partly filled with catalytic nanoparticles. A combination of water and methanol flows through the tubes, which are sealed in a vacuum.
“This set-up allows up to 95 percent of the sunlight to be absorbed with very little being lost as heat to the surroundings,” Hotz said. “This is crucial because it permits us to achieve temperatures of well over 200 degrees Celsius within the tubes. By comparison, a standard solar collector can only heat water between 60 and 70 degrees Celsius.”
Once the evaporated liquid achieves these higher temperatures, tiny amounts of a catalyst are added, which produces hydrogen. This combination of high temperature and added catalysts produces hydrogen very efficiently, Hotz said. The resulting hydrogen can then be immediately directed to a fuel cell to provide electricity to a building during the day, or compressed and stored in a tank to provide power later.
The three systems examined in the analysis were the standard photovoltaic cell which converts sunlight directly into electricity to then split water electrolytically into hydrogen and oxygen; a photocatalytic system producing hydrogen similar to Hotz’s system, but simpler and not mature yet; and a system in which photovoltaic cells turn sunlight into electricity which is then stored in different types of batteries (with lithium ion being the most efficient).
“We performed a cost analysis and found that the hybrid solar-methanol is the least expensive solution, considering the total installation costs of $7,900 if designed to fulfill the requirements in summer, although this is still much more expensive than a conventional fossil fuel-fed generator,” Hotz said.
Costs and efficiencies of systems can vary widely depending on location — since the roof-mounted collectors that could provide all the building’s needs in summer might not be enough for winter. A rooftop system large enough to supply all of a winter’s electrical needs would produce more energy than needed in summer, so the owner could decide to shut down portions of the rooftop structure or, if possible, sell excess energy back to the grid.
“The installation costs per year including the fuel costs, and the price per amount of electricity produced, however showed that the (hybrid) solar scenarios can compete with the fossil fuel-based system to some degree,” Hotz said. ‘In summer, the first and third scenarios, as well as the hybrid system, are cheaper than a propane- or diesel-combusting generator.”
This could be an important consideration, especially if a structure is to be located in a remote area where traditional forms of energy would be too difficult or expensive to obtain.
Hotz’s research was supported by the Swiss National Science Fund. Joining him in the study were UC-Berkeley’s Heng Pan and Costas Grigoropoulos, as well as Seung H. Ko of the Korea Advanced Institute of Science and Technology, Daejon.
Holograms Reveal Brain's Inner Workings: Microscopy Technique Used to Observe Activity of Neurons Like Never Before
This is a 3-D image of living neuron taken by DHM technology. (Credit: Courtesy of Lyncée Tec)
Like far away galaxies, powerful tools are required to bring the minute inner workings of neurons into focus. Borrowing a technique from materials science, a team of neurobiologists, psychiatrists, and advanced imaging specialists from Switzerland’s EPLF and CHUV report in The Journal of Neuroscience how Digital Holographic Microscopy (DHM) can now be used to observe neuronal activity in real-time and in three dimensions — with up to 50 times greater resolution than ever before. The application has immense potential for testing out new drugs to fight neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
Neurons come in various shapes and are transparent. To observe them in a Petri dish, scientists use florescent dyes that change the chemical composition and can skew results. Additionally, this technique is time consuming, often damages the cells, and only allows researchers to examine a few neurons at a time. But these newly published results show how DHM can bypass the limitations of existing techniques.
“DHM is a fundamentally novel application for studying neurons with a slew of advantages over traditional microscopes,” explains Pierre Magistretti of EPFL’s Brain Mind Institute and a lead author of the paper. “It is non-invasive, allowing for extended observation of neural processes without the need for electrodes or dyes that damage cells.”
Senior team member Pierre Marquet adds, “DHM gives precious information not only about the shape of neurons, but also about their dynamics and activity, and the technique creates 3D navigable images and increases the precision from 500 nanometers in traditional microscopes to a scale of 10 nanometers.”
A good way to understand how DHM works is to imagine a large rock in an ocean of perfectly regular waves. As the waves deform around the rock and come out the other side, they carry information about the rock’s shape. This information can be extracted by comparing it to waves that did not smash up against the rock, and an image of the rock can be reconstructed. DHM does this with a laser beam by pointing a single wavelength at an object, collecting the distorted wave on the other side, and comparing it to a reference beam. A computer then numerically reconstructs a 3D image of the object — in this case neurons — using an algorithm developed by the authors. In addition, the laser beam travels through the transparent cells and important information about their internal composition is obtained.
Normally applied to detect minute defects in materials, Magistretti, along with DHM pioneer and EPFL professor in the Advanced Photonics Laboratory, Christian Depeursinge, decided to use DHM for neurobiological applications. In the study, their group induced an electric charge in a culture of neurons using glutamate, the main neurotransmitter in the brain. This charge transfer carries water inside the neurons and changes their optical properties in a way that can be detected only by DHM. Thus, the technique accurately visualizes the electrical activities of hundreds of neurons simultaneously, in real-time, without damaging them with electrodes, which can only record activity from a few neurons at a time.
A major advance for pharmaceutical research
Without the need to introduce dyes or electrodes, DHM can be applied to High Content Screening — the screening of thousands of new pharmacological molecules. This advance has important ramifications for the discovery of new drugs that combat or prevent neurodegenerative diseases such as Parkinson’s and Alzheimer’s, since new molecules can be tested more quickly and in greater numbers.
“Due to the technique’s precision, speed, and lack of invasiveness, it is possible to track minute changes in neuron properties in relation to an applied test drug and allow for a better understanding of what is happening, especially in predicting neuronal death,” Magistretti says. “What normally would take 12 hours in the lab can now be done in 15 to 30 minutes, greatly decreasing the time it takes for researchers to know if a drug is effective or not.”
The promise of this technique for High Content Screening has already resulted in a start-up company at EPFL called LynceeTec (www.lynceetec.com).
Phone Losing Charge? With Photovoltaic Polarizers, Devices Could Be Powered by Sunlight, Own Backlight
We’ve all worried about the charge on our smartphone or laptop running down when we have no access to an electrical outlet. But new technology developed by researchers at the UCLA Henry Samueli School of Engineering and Applied Science could finally help solve the problem.
The UCLA engineers have created a novel concept for harvesting and recycling energy for electronic devices — one that involves equipping these devices’ LCD screens with built-in photovoltaic polarizers, allowing them to convert ambient light, sunlight and their own backlight into electricity.
LCDs, or liquid crystal displays, are used in many of today’s electronic devices, including smartphones, TV screens, computer monitors, laptops and tablet computers. They work by using two polarized sheets that let only a certain amount of a device’s backlight pass through. Tiny liquid crystal molecules are sandwiched between the two polarizers, and these crystals can be switched by tiny transistors to act as light valves. Manipulating each light valve, or pixel, lets a certain amount of the backlight escape; millions of pixels are combined to create images on LCDs.
The UCLA Engineering team created a new type of energy-harvesting polarizer for LCDs called a polarizing organic photovoltaic, which can potentially boost the function of an LCD by working simultaneously as a polarizer, a photovoltaic device and an ambient light or sunlight photovoltaic panel.
Their research findings are currently available in the online edition of the journal Advanced Materials and will be published in a forthcoming print issue of the journal.
“I believe this is a game-changer invention to improve the efficiency of LCD displays,” said Yang Yang, a professor of materials science at UCLA Engineering and principal investigator on the research. “In addition, these polarizers can also be used as regular solar cells to harvest indoor or outdoor light. So next time you are on the beach, you could charge your iPhone via sunlight.”
From the point of view of energy use, current LCD polarizers are inefficient, the researchers said. A device’s backlight can consume 80 to 90 percent of the device’s power. But as much as 75 percent of the light generated is lost through the polarizers. A polarizing organic photovoltaic LCD could recover much of that unused energy.
“In the near future, we would like to increase the efficiency of the polarizing organic photovoltaics, and eventually we hope to work with electronic manufacturers to integrate our technology into real products,” Yang said. “We hope this energy-saving LCD will become a mainstream technology in displays.”
“Our coating method is simple, and it can be applied in the future in large-area manufacturing processes,” said Rui Zhu, a postdoctoral researcher at UCLA Engineering and the paper’s lead author.
“The polarizing organic photovoltaic cell demonstrated by Professor Yang’s research group can potentially harvest 75 percent of the wasted photons from LCD backlight and turn them back into electricity,” said Youssry Boutros, program director for the Intel Labs Academic Research Office, which supported the research. “The strong collaboration between this group at UCLA Engineering and other top groups has led to higher cell efficiencies, increasing the potential for harvesting energy. This approach is interesting in its own right and at the same time synergetic with several other projects we are funding through the Intel Labs Academic Research Office.”
Ankit Kumar, a materials science and engineering graduate student at UCLA Engineering was the paper’s second author.
Yang, who holds UCLA’s Carol and Lawrence E. Tannas Jr. Endowed Chair in Engineering, is also faculty director of the Nano Renewable Energy Center at the California NanoSystems Institute at UCLA.
The research was supported by Intel through a gift to UCLA, and by the Office of Naval Research.
Miniature Power Plants for Aircraft Bodies
The energy-harvester-module. (Credit: Image courtesy of Vienna University of Technology, TU Vienna)
Sensor networks are supposed to pervade the body shell of airplanes in the future — much like a nervous system. Thanks to a joint research project of EADS Germany and the Vienna University of Technology, these sensors do not require any external power supply.
Aircraft maintenance can be time consuming and expensive. It is much simpler if the airplane itself reports, where maintenance is required. The best solution is a sensor system, which even has its own power supply and is therefore independent of electrical wiring — and this is what has now been developed by EADS Germany, in cooperation with the Institute of Sensor and Actuator Systems at Vienna University of Technology (TU Vienna). For each individual sensor, electricity is produced by a thermoelectric generator with a small water tank, storing thermal energy. The electricity is simply generated from the temperature difference between the icy cold air in high altitudes and the air close to the ground. This new sensor technology could not only facilitate aircraft maintenance, but also increase comfort for travelers.
Energy from the “Energy Harvester Module”
Even small collisions can easily lead to damage in the body of the aircraft. On aluminum bodies, a slight dent may be visible — but on modern carbon materials, it is much harder to detect damage. Tiny, invisible cracks may appear, which are very hard to detect. With suitable sensors connected directly to the body of the aircraft, this could be constantly monitored. “A major problem with these sensors is the energy supply. Wiring up hundreds of sensors in the aircraft body is complicated and expensive,” professor Ulrich Schmid from the Institute for Sensor and Actuator Systems at TU Vienna explains. For this reason, he — together with Dominik Samson and professor Thomas Becker (EADS Germany) — developed the idea of the “thermoelectric energy harvester” as an energy source, in order to be completely independent of batteries and wiring.
Electrical Current from Differences in Temperature
When an airplane rises to an altitude of thousands of meters, the exterior wall cools down. “From the temperature difference between the exterior and the interior, we can harvest energy for the sensor element, using a thermoelectric generator,” Dominik Samson explains. In the energy-harvester module, there is a little water tank which can store the ground temperature for a while. Water is especially well suited for this task, because it can store large quantities of energy in terms of heat. The inner part of the module with the water tank is connected to the cold exterior wall via the thermoelectric generator. Therefore, a gradient in temperature arises at the generator, which can be used to create electrical voltage. During landing, it works the other way around: The plane heats up again, whereas the inner part of the module is still cold — and again, electricity can be produced.
Whenever there is no thermoelectric current, for instance right after takeoff and during the landing, sophisticated electronics controls storage and transfer of electrical energy. The electronics and the components which create electricity only take up very little space: They fit on the palm of a hand and can easily be integrated into the aircraft body. The size can be adjusted for the individual energy demand of different applications.
No Wires, no Batteries
The data collected by the sensor can be transmitted wirelessly. Wireless technology does not only make maintenance easier, it also minimizes potential causes of defect and it reduces the weight of the airplane. During one flight, the energy harvester can provide the energy of eight to ten milliwatt hours — which is sufficient for a wireless sensor. “A plane has a durability of roughly thirty years. If the sensors were operated with batteries, each of them would use up about one hundred batteries during this time,” Dominik Samson estimates. Using a large number of sensors, this would not only require costly maintenance but it would also create unnecessary amounts of waste.
The concept of generating electricity in the airplane by utilizing differences in temperature could also be used for other purposes. Sensors could monitor whether the passengers have fastened their seatbelts or whether the tables are in an upright position. At the push of a button, a wireless signal could be transmitted to the flight attendants — without expensive and complicated wiring, just powered by the body heat of the passengers. “The first and most important step has been taken. We are confident that this wireless sensor technology will travel on board of many airplanes soon,” Ulrich Schmid says.
Sketching With Superconductors: Breakthrough in Controlling Defects Could Lead to New Generation of Electronic Devices
Reporting in the journal Nature Materials, researchers from the London Centre for Nanotechnology and the Physics Department of Sapienza University of Rome have discovered a technique to ‘draw’ superconducting shapes using an X-ray beam. This ability to create and control tiny superconducting structures has implications for a completely new generation of electronic devices.
In future, X-ray beams could be used to write superconducting circuits, such as those depicted in the image. Here, solid lines indicate electrical connections while semicircles denote superconducting junctions, whose states are indicated by red arrows.
Superconductivity is a special state where a material conducts electricity with no resistance, meaning absolutely zero energy is wasted.
The research group has shown that they can manipulate regions of high temperature superconductivity, in a particular material which combines oxygen, copper and a heavier, ‘rare earth’ element called lanthanum. Illuminating with X-rays causes a small scale re-arrangement of the oxygen atoms in the material, resulting in high temperature superconductivity, of the type originally discovered for such materials 25 years ago by IBM scientists. The X-ray beam is then used like a pen to draw shapes in two dimensions.
A well as being able to write superconductors with dimensions much smaller than the width of a human hair, the group is able to erase those structures by applying heat treatments. They now have the tools to write and erase with high precision, using just a few simple steps and without the chemicals ordinarily used in device fabrication. This ability to re-arrange the underlying structure of a material has wider applications to similar compounds containing metal atoms and oxygen, ranging from fuel cells to catalysts.
Prof. Aeppli, Director of the London Centre for Nanotechnology and the UCL investigator on the project, said: “Our validation of a one-step, chemical-free technique to generate superconductors opens up exciting new possibilities for electronic devices, particularly in re-writing superconducting logic circuits. Of profound importance is the key to solving the notorious ‘travelling salesman problem’, which underlies many of the world’s great computational challenges. We want to create computers on demand to solve this problem, with applications from genetics to logistics. A discovery like this means a paradigm shift in computing technology is one step closer.”
Prof Bianconi, the leader of the team from Sapienza, added: “It is amazing that in a few simple steps, we can now add superconducting ‘intelligence’ directly to a material consisting mainly of the common elements copper and oxygen.”
The X-ray experiments were performed at the Elettra (Trieste) synchrotron radiation facility. The work is published in Nature Materials , 21 August 2011 (doi:1038/nmat3088) and follows on from previous discovery of fractal-like structures in superconductors (doi:10.1038/nature09260).
World-Record Pulsed Magnetic Field Achieved; Lab Moves Closer to 100-Tesla Mark
Researchers at the National High Magnetic Field Laboratory’s Pulsed Field Facility at Los Alamos National Laboratory have set a new world record for the strongest magnetic field produced by a nondestructive magnet.
The scientists achieved a field of 92.5 tesla on Thursday, August 18, taking back a record that had been held by a team of German scientists and then, the following day, surpassed their achievement with a whopping 97.4-tesla field. For perspective, Earth’s magnetic field is 0.0004 tesla, while a junk-yard magnet is 1 tesla and a medical MRI scan has a magnetic field of 3 tesla.
The ability to create pulses of extremely high magnetic fields nondestructively (high-power magnets routinely rip themselves to pieces due to the large forces involved) provides researchers with an unprecedented tool for studying fundamental properties of materials, from metals and superconductors to semiconductors and insulators. The interaction of high magnetic fields with electrons within these materials provides valuable clues for scientists about the properties of materials. With the recent record-breaking achievement, the Pulsed Field Facility at LANL, a national user facility, will routinely provide scientists with magnetic pulses of 95 tesla, enticing the worldwide user community to Los Alamos for a chance to use this one-of-a-kind capability.
The record puts the Los Alamos team within reach of delivering a magnet capable of achieving 100 tesla, a goal long sought by researchers from around the world, including scientists working at competing magnet labs in Germany, China, France, and Japan.
Such a powerful nondestructive magnet could have a profound impact on a wide range of scientific investigations, from how to design and control material functionality to research into the microscopic behavior of phase transitions. This type of magnet allows researchers to carefully tune material parameters while perfectly reproducing the non-invasive magnetic field. Such high magnetic fields confine electrons to nanometer scale orbits, thereby helping to reveal the fundamental quantum nature of a material.
Thursday’s experiment was met with as much excitement as trepidation by the group of condensed matter scientists, high-field magnet technicians, technologists, and pulsed-magnet engineers who gathered to witness the NHMFL-PFF retake the world record. Crammed into the tight confines of the Magnet Lab’s control room, they gathered, lab notebooks or caffeine of choice in hand. Their conversation reflected a giddy sense of anticipation tempered with nervousness.
With Mike Gordon commanding the controls that draw power off of a massive 1.4-gigawatt generator system and directs it to the magnet, all eyes and ears were keyed to video monitors showing the massive 100 tesla Multishot Magnet and the capacitor bank located in the now eerily empty Large Magnet Hall next door. The building had been emptied as a standard safety protocol.
Scientists heard a low warping hum, followed by a spine-tingling metallic screech signaling that the magnet was spiking with a precisely distributed electric current of more than 100 megajoules of energy. As the sound dissipated and the monitors confirmed that the magnet performed perfectly, attention turned to data acquired during the shot through two in-situ measurements — proof positive that the magnet had achieved 92.5 tesla, thus yanking back from a team of German scientists a record that Los Alamos had previously held for five years.
The next day’s even higher 97.4-tesla achievement was met with high-fives and congratulatory pats on the back. Later, researchers Charles Mielke, Neil Harrison, Susan Seestrom, and Albert Migliori certified with their signatures the data that would be sent to the Guiness Book of World Records.
The NHMFL is sponsored primarily by the National Science Foundation, Division of Materials Research, with additional support from the State of Florida and the DOE. These recent successes were enabled by long-term support from the U.S. Department of Energy’s Office of Basic Energy Sciences, and the National Science Foundation’s 100 Tesla Multi-Shot magnet program.
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