New materials are critical enabling technology for future products that are smaller, faster, smarter and stronger. Researchers at the MagLab and other high magnetic filed facilities use high-powered magnets to help discover, explore and understand materials. These materials then become the building blocks of new products. High magnetic fields are a critical link in the development of new materials that impact nearly every modern technology.
The magnetic field is the area around a magnet in which there is magnetic force. The Earth produces its own magnetic field, which shields the Earth’s ozone layer from the solar wind and is important in navigation using a compass.A charge that is moving in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. The effects of magnetic fields are commonly seen in permanent magnets, which pull on magnetic materials such as iron, and attract or repel other magnets. In addition, a magnetic field that varies with location will exert a force on a range of non-magnetic materials by affecting the motion of their outer atomic electrons.
Moving electric charges can make magnetic fields. Magnetic fields surround magnetized materials, and are created by electric currents such as those used in electromagnets, and by electric fields varying in time. Magnetic fields are produced by moving electric charges and the intrinsic magnetic moments of elementary particles associated with a fundamental quantum property, their spin. The Earth produces its own magnetic field, which shields the Earth’s ozone layer from the solar wind and is important in navigation using a compass.
Electric lights, computers, motors, plastics, high speed trains, and MRI all came about after researchers learned more about materials and living structures through magnet-related research. Semi- and super- conducting materials, are leading to the products of tomorrow. Semiconductors conduct current, and are widely used in microprocessors and modern electronics from televisions to cell phones. Superconductors are materials that conduct electricity without resistance, but only at very cold temperatures (around -242 degrees Celsius). Research on making superconductivity possible at higher temperatures could lead to smart electrical grids, power storage devices or magnetic levitation.
Fullerenes are carbon-based molecules that are widely studied in high magnetic fields. One type of fullerene, buckyballs, are spheres of carbon, plentiful in space, that may one day teach us about the origins of life in the universe. Work on buckytubes could help make products stronger and lighter, and a new carbon-based material, graphene, may lead to an array of exciting products, from thin, flexible computer screens that can be rolled up like a sheet of paper to quantum computers that can process complex calculations using quantum-mechanical phenomena.
Certain crystals contain optical, electrical and magnetic properties that can be used for computer memory storage. Even natural materials, such as spider silk, have amazing properties that could make electronics and computers that could bend and stretch like spandex. Research on more powerful permanent magnetic materials will also be key to improving the energy efficiency of motors in car engines, air conditioners, robots and other devices.
To date, the strongest magnetic fields produced in the laboratory have been in the kilotesla (kT) range. This is far stronger than the magnetic field of the Earth, which is 0.3–0.5 × 10–4 T, and substantially exceeds the fields produced in magnetic tomography (MRI) machines (about 1 T). While fields in this lower range are important experimental tools, stronger fields could make it possible to study fundamental physics phenomena in areas such as plasma and beam physics, astrophysics and solar physics.
The extreme high magnetic field (B) environment, generally coupled with elevated temperature (T), provides an enabling disruptive technology for making significant major science and technological advances in developing the next generation of novel structural and functional materials for broad energy and military applications, says ONR.
All materials are impacted by high magnetic fields and so all material systems from metallic through polymeric and protein will respond to a BT environment. Major improvements in performance (from 15% to 300%) can be manifested in mechanical and/or physical properties as well as the development of nanocrystalline or textured microstructures or reaction paths made easier/faster through the synthesis/catalytic chemical effect of the extreme BT environment.
In addition, the deformation behavior (magnetoplasticity) of materials appears to be impacted by high fields potentially enabling high and low cycle fatigue damage mitigation superplastic behavior at ambient temperature, residual stress relief, and other visionary applications. Perhaps classically brittle materials can be made to be formable under high magnetic fields. The BT environment therefore impacts phase equilibria and kinetics, is a new synthesis/catalysis paradigm, and a deformation/life enhancement processing breakthrough technology.
Researchers are therefore exploring various ways of producing such super-strength fields – including collisional shocks, gamma rays and fusion in strongly magnetized plasmas, as well as explosives, high-power lasers and devices known as z-pinches, which have been used for decades by astronomers to recreate the hot plasmas that exist inside stars.
Worldwide high magnetic field facilities
The Florida State University-based National High Magnetic Field Laboratory has the strongest magnet in the world for nuclear magnetic resonance (NMR) spectroscopy, a powerful technique used to study molecular structures in proteins and materials. The 33-ton engineering marvel, called the series connected hybrid (SCH) magnet, successfully broke the record in 2016 during a series of tests conducted by MagLab engineers and scientists. The instrument reached its full field of 36 tesla .Tesla is a unit of magnetic field strength. For example, a strong refrigerator magnet is .01 tesla, and a typical MRI machine is 1.5 to 3 tesla.
The National High Magnetic Field Laboratory (NHMFL) develops and operates high magnetic field facilities that scientists use for research in physics, biology, bioengineering, chemistry, geochemistry, biochemistry, materials science, and engineering. It is the only facility of its kind in the United States and one of only nine in the world. It is the largest and highest powered magnet laboratory, outfitted with the world’s most comprehensive assortment of high-performing magnet systems. Many of the unique facilities were designed, developed, and built by the world’s premier magnet engineering and design team of the NHMFL in collaboration with industry.
Research at the NHMFL-conducted at the frontiers of science-will underpin the technologies of the 21st century and improve the quality of life for all Americans. Among many other activities, the laboratory is actively engaged with efforts to restore the Florida Everglades, grow protein crystals in zero gravity (significantly more cost effective than similar Space Shuttle experiments), and develop power technologies for the all-electric ship to be used by the U.S. Navy and in public utility areas.
Japan’s Center for Advanced High Magnetic Field Science, abbreviated as AHMF center, was launched in April, 2014 as the AHMF center in a graduate school of science. The AHMF center has two high magnetic field facilities with large capacitor bank systems (10 MJ and 1.5 MJ maximum charged energy for the first and second high magnetic field facilities, respectively). These capacitor bank systems and homemade pulse magnets enable them to produce high magnetic fields beyond 50 Tesla.
In the first high magnetic field facility, pulsed magnetic fields with a typical duration of about 35 msec are generated, and transport and magnetization measurements have been conducted on mainly conductive materials, such as high-Tc superconductors and heavy-fermion materials. In the second high magnetic field facility, magnetization and electron spin resonance (ESR) measurements are carried out on insulating materials such as frustrated magnets and low-dimensional magnets in short pulsed magnetic fields with the duration of about 7 msec.
China completes construction of steady high magnetic field facility
Now China has completed construction of the Steady High Magnetic Field Facility, a project of China’s National 11th Five-Year Major Science and Technology Infrastructure constructed by High Magnetic Field Laboratory, Chinese Academy of Sciences (CHMFL). The project passed China’s national acceptance on Sep. 27th, 2017 in Hefei, Anhui. The completion takes China’s high magnetic field technology to a new level. The country now has the means for scientists to carry out frontier research on condensed matter physics, magnetism, material science, chemistry, life science and medicine.
“The successful testing of the Hefei Hybrid Magnet has placed China on the world map of international research in very high magnetic fields,” said Hans Schneider Muntau, high field magnet expert and former chief engineer of the Grenoble High Magnetic Field Laboratory of France and the National High Magnetic Field Laboratory of the U.S.
The project was jointly proposed by Chinese Academy of Sciences and Ministry of Education in 2005 and approved by the National Development and Reform Commission in 2008. After years of effort, CHMFL now has 10 magnets, six measurement systems and extreme low-temperature and high-pressure experimental systems.
It’s the world’s second 40-tesla-level hybrid magnet, with three water-cooled magnets that set world records and the world’s first three-in-one microscope SMA (scanning tunneling microscope/magnetic force microscope/atomic force microscope), and establishes an advanced scientific experiment system, achieving a major breakthrough of China’s steady high magnetic technology. “CHMFL summarizes 10 years of enormous and exemplary efforts under the groundbreaking leadership, which were necessary to create know-how and competence in the generation and exploitation of very high magnetic fields,” Hans Schneider Muntau said.
National MagLab racks up new world record with hybrid magnet
“This achievement reflects a tremendous amount of technology development,” said Director of Magnet Science and Technology Mark Bird. Bird, who has overseen 20 unique magnet projects at the lab, called the SCH “one of the most complicated magnets ever built at the MagLab, a testament to a great team working with great determination.” What makes the SCH unique is that it can create a very high magnetic field that is also of very high quality. For magnets, quality means a field that remains constant over both the time it takes to run an experiment and the space in which the experiment takes place in the magnet. Unlike most of the physics research done in magnets, NMR requires fields that are very stable and homogeneous.
At 36 tesla, the SCH is more than 40 percent stronger than the previous world-record NMR magnet (the MagLab’s Keck magnet) and more than 50 percent more powerful than the highest field high-resolution NMR magnet, a 23.5 tesla system in Lyon, France. Magnetic Resonance Imaging (MRI) is an imaging technique used primarily in medical settings to produce high quality images of the inside of the human body. MRI is based on the principles of nuclear magnetic resonance (NMR). The human body is primarily fat and water. Fat and water have many hydrogen atoms which make the human body approximately 63% hydrogen atoms. For these reasons magnetic resonance imaging primarily images the NMR signal from the hydrogen nuclei.
In NMR, scientists use magnets and radio waves to locate a specific element (commonly hydrogen) in proteins and other samples, which helps them figure out those complex structures. A powerful technique in health research, scientists use it, for example, to pinpoint a virus’ vulnerability to drugs. Existing NMR magnets are limited to locating just a handful of elements, notably hydrogen, carbon and nitrogen. The SCH’s 36-tesla field could revolutionize NMR because it significantly boosts the instrument’s sensitivity, expanding the menu of elements scientists can see.
“There’s going to be a real increase in the reach of NMR into the periodic table,” said Tim Cross, who oversees NMR research at the MagLab’s FSU headquarters. “So we’re going to be able to look at many more elements than we’ve really been able to in the past.” Zinc, copper, aluminum, nickel and gadolinium—all of interest for battery and other materials research—will now be observable using the SCH. But for most biologists, the real prize will be oxygen. “Oxygen is where so much biological chemistry takes place,” Cross said, “and until the SCH, we’ve just not been able to look at it.” The new magnet will also allow researchers to vary the field strength and switch relatively easily from examining one element in a sample to another, which will help them to collect more and better data.
Microtube implosions could produce megatesla magnetic fields
A newly discovered mechanism known as microtube implosion could make it possible to generate magnetic fields 1000 times stronger than any yet seen in the laboratory. According to the researchers who developed it at Japan’s Osaka University, the new method could be used to generate super-strong magnetic fields for fundamental research in fields such as materials science, quantum electrodynamics and astrophysics.
Most of existing approaches begin by taking the magnetic flux from “pre-seeded” strong magnetic fields and attempting to confine it within hollow cylindrical structures. A team led by Masakatsu Murakami has now used a similar physical configuration, but with a twist: the ultrahigh magnetic fields in its microtube implosion technique are generated by the spin currents created as charged particles are spun around by the Lorentz force, which acts on moving charged particles in a magnetic field.
In their work, the researchers simulated using high-intensity laser pulses of around 1020–1022 W/cm2 to irradiate a micron-sized plastic tube lined with a structured “target” material. This intense radiation produces “hot” electrons (that is, electrons with a lot of kinetic energy) that have temperatures equivalent to a few tens of mega-electron volts (MeV). These high-energy electrons cause the target material in the tube to ionize, producing a plasma that subsequently expands into the tube at near-relativistic speeds (the implosion).
In an idealized configuration with no pre-seeded magnetic fields present, this procedure will not generate strong magnetic fields. However, the researchers found that if they introduced a kilotesla-order magnetic field into their simulated system, they could generate an “extraordinary” magnetic field at the centre of the microtube that is 100–1000 times stronger than the pre-seeded field. Such strong magnetic fields are expected only in celestial bodies like neutron stars and black holes, Murakami says.
So what is happening? Murakami explains that during the implosion, the Lorentz force deflects the ions and electrons in the plasma in opposite directions so that they become twisted – an effect known as Larmor gyration. The resultant collective motion of the relativistic charge particles around the central axis of the microtube produces strong spin currents with densities of around 1015 ampere/cm2. These spin currents, he says, are what subsequently generate megatesla-order magnetic fields in the centre of the tube.
“Our new study, detailed in Scientific Reports, is a proof-of-principle that current laser technology can be used to create megatesla-sized magnetic fields,” Murakami tells Physics World. “We now plan to investigate high-energy-density physics such as particle acceleration, developing compact fusion devices and electron-positron pair creation using the new concept of microtube implosion.”