World-Record Pulsed Magnetic Field Achieved; Lab Moves Closer to 100-Tesla Mark

World-Record Pulsed Magnetic Field Achieved; Lab Moves Closer to 100-Tesla Mark

  10:14:00 AM    Science Lover

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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.

Yates Coulter, left, and Mike Gordon of Los Alamos National Laboratory make final preparations before successfully achieving a world-record for the strongest magnetic field produced by a nondestructive magnet. Working at the National High Magnetic Field Laboratory's Pulsed Field Facility at Los Alamos, a team of researchers achieved a field of 97.4 tesla, which is nearly 100 times stronger than the magnetic field found in giant electromagnets used in metal scrap yards. (Credit: Image courtesy of DOE/Los Alamos National Laboratory)

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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Hydrogen Storage Gets New Hope

Hydrogen Storage Gets New Hope

  9:28:00 PM    Science Lover

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A new method for “recycling” hydrogen-containing fuel materials could open the door to economically viable hydrogen-based vehicles.

Ammonia borane (AB) is a potential hydrogen releasing fuel. In this Los Alamos National Laboratory graphic, the AB would be used on-board the vehicle to run a fuel cell. Once hydrogen is released, the AB could then be regenerated and reused. In the scheme shown,
the recycle of dehydrogenated fuel back into AB would take place off-board the vehicle.
(Credit: Image courtesy of DOE/Los Alamos National Laboratory)

In an article appearing in Angewandte Chemie, Los Alamos National Laboratory and University of Alabama researchers working within the U.S. Department of Energy’s Chemical Hydrogen Storage Center of Excellence describe a significant advance in hydrogen storage science.

Hydrogen is in many ways an ideal fuel for transportation. It is abundant and can be used to run a fuel cell, which is much more efficient than internal combustion engines. Its use in a fuel cell also eliminates the formation of gaseous byproducts that are detrimental to the environment.

For use in transportation, a fuel ideally should be lightweight to maintain overall fuel efficiency and pack a high energy content into a small volume. Unfortunately, under normal conditions, pure hydrogen has a low energy density per unit volume, presenting technical challenges for its use in vehicles capable of travelling 300 miles or more on a single fuel tank—a benchmark target set by DOE.

Consequently, until now, the universe’s lightest element has been considered by some as a lightweight in terms of being a viable transportation fuel.

In order to overcome some of the energy density issues associated with pure hydrogen, work within the Chemical Hydrogen Storage Center of Excellence has focused on using a class of materials known as chemical hydrides. Hydrogen can be released from these materials and potentially used to run a fuel cell. These compounds can be thought of as “chemical fuel tanks” because of their hydrogen storage capacity.

Ammonia borane is an attractive example of a chemical hydride because its hydrogen storage capacity approaches a whopping 20 percent by weight. The chief drawback of ammonia borane, however, has been the lack of energy-efficient methods to reintroduce hydrogen back into the spent fuel once it has been released. In other words, until recently, after hydrogen release, ammonia borane couldn’t be adequately recycled.

Los Alamos researchers have been working with University of Alabama colleagues on developing methods for the efficient recycling of ammonia borane. The research team made a breakthrough when it discovered that a specific form of dehydrogenated fuel, called polyborazylene, could be recycled with relative ease using modest energy input. This development is a significant step toward using ammonia borane as a possible energy carrier for transportation purposes.

“This research represents a breakthrough in the field of hydrogen storage and has significant practical applications,” said Dr. Gene Peterson, leader of the Chemistry Division at Los Alamos. “The chemistry is new and innovative, and the research team is to be commended on this excellent achievement.”

The Chemical Hydrogen Storage Center of Excellence is one of three Center efforts funded by DOE. The other two focus on hydrogen sorption technologies and storage in metal hydrides. The Center of Excellence is a collaboration between Los Alamos, Pacific Northwest National Laboratory, and academic and industrial partners.

Referring to the work described in the Angewandte Chemie article, Los Alamos researcher John Gordon, corresponding author for the paper, stated, “Collaboration encouraged by our Center model was responsible for this breakthrough. At the outset there were myriad potential reagents with which to attempt this chemistry.”

“The predictive calculations carried out by University of Alabama professor Dave Dixon’s group were crucial in guiding the experimental work of Los Alamos postdoctoral researcher Ben Davis,” Gordon added. “The excellent synergy between these two groups clearly enabled this advance.”

The research team currently is working with colleagues at The Dow Chemical Company, another Center partner, to improve overall chemical efficiencies and move toward large-scale implementation of hydrogen-based fuels within the transportation sector.

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Shifting Sound To Light May Lead To Better Computer Chips

Shifting Sound To Light May Lead To Better Computer Chips

  1:29:00 AM    Science Lover

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A plasma is generated by a laser pulse similar to how sound is converted to light.
(Credit: Image courtesy of DOE/Lawrence Livermore National Laboratory)

By reversing a process that converts electrical signals into sounds heard out of a cell phone, researchers may have a new tool to enhance the way computer chips, LEDs and transistors are built.

Lawrence Livermore National Laboratory scientists have for the first time converted the highest frequency sounds into light by reversing a process that converts electrical signals to sound.

Commonly used piezo-electric speakers, such as those found in a cell phone, operate at low frequencies that human ears can hear.

But by reversing that process, lead researchers Michael Armstrong, Evan Reed and Mike Howard, LLNL colleagues, and collaborators from Los Alamos National Laboratory and Nitronex Corp., used a very high frequency sound wave - about 100 million times higher frequency than what humans can hear - to generate light.

“This process allows us to very accurately ‘see’ the highest frequency sound waves by translating them into light,” Armstrong said.

The research appears in the March 15 edition of the journal Nature Physics.

During the last decade, pioneering experiments using sub-picosecond lasers have demonstrated the generation and detection of acoustic and shock waves in materials with terahertz (THz) frequencies. These very same experiments led to a new technique for probing the structure of semiconductor devices.

However, the recent research takes those initial experiments a step further by reversing the process, converting high-frequency sound waves into electricity. The researchers predicted that high frequency acoustic waves can be detected by seeing radiation emitted when the acoustic wave passes an interface between piezoelectric materials.

Very high-frequency sound waves have wavelengths approaching the atomic-length scale. Detection of these waves is challenging, but they are useful for probing materials on very small length scales.

But that’s not the only application, according to Reed.

“This technique provides a new pathway to generation of THz radiation for security, medical and other purposes,” he said. “In this application, we would utilize acoustic-based technologies to generate THz.” Security applications include explosives detection and medical use may include detection of skin cancer.

And the Livermore method doesn’t require any external source to detect the acoustic waves.

“Usually scientists use an external laser beam that bounces off the acoustic wave – much like radar speed detectors – to observe high frequency sound. An advantage of our technique is that it doesn’t require an external laser beam – the acoustic wave itself emits light that we detect,” Armstrong said.

Article source : ScienceDaily

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