Posts Tagged ‘magnets’
Magnetic Microprocessors Could Enable the Most Efficient Computers Physically Possible
For now, computers run on electricity, which means electrons moving around and generating waste heat. But a magnetic microprocessor would not need any electrons. Instead, it would use the polarity of nanoscale bar magnets to represent the 0 and 1 of binary memory. If the nanomagnets are packed close together, their poles will interact, serving as transistors and thereby allowing simple logic operations.
Jeffrey Bokor, UC Berkeley professor of electrical engineering and computer sciences, and grad student Brian Lambson are trying to develop these magnetic computers. Their goal is a computer that operates at the Landauer limit, which at room temperature equates to a loss of 18 millielectron volts of energy per operation. This is the minimum energy that a single logic operation, like AND or OR, would dissipate. A physicist named Rolf Landauer computed this limit 50 years ago.
That number, 18 thousandths of an electron volt, is the merest whiff of energy — for comparison, it is about half the thermal energy of atoms at room temperature. The Large Hadron Collider collides particles at a maximum of 7 trillion electron volts, which is equal to the energy you'd get from eating 0.00013 micrograms of a candy bar.
A computer that uses such infinitesimal power would be a major advancement, Bokor said in a Berkeley news release. If it the computer could work at colder temperatures, it would be even more efficient (the Landauer limit is proportional to temperature).
“Even if we could get within one order of magnitude, a factor of 10, of the Landauer limit, it would represent a huge reduction in energy consumption for electronics,” he said. “It would be absolutely revolutionary.”
Lambson and Bokor wanted to test the energy efficiency of a simple magnetic logic circuit and magnetic memory, so they conducted calculations and computer simulations. They found a simple memory operation, such as erasing a magnetic bit, “can be conducted with an energy dissipation very close, if not identical to, the Landauer limit,” the says.
Current tests of these systems still require an electrical current to generate a magnetic field, which flips or erases a nanomagnet’s polarity. But Bokor and colleagues hope that new materials, such as , could make the electrical currents unnecessary. A new era of magnetonics, instead of electronics, could be in our future.
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Inside the World’s Largest Fusion Reactor
Hot fusion might be the answer to energy demands
At the forefront of the effort to realize fusion-based power is , an international collaboration to build the world’s largest fusion reactor. At the heart of the project is a tokamak, a doughnut-shaped vessel that contains the fusion reaction. In this vessel, magnetic fields confine a plasma composed of deuterium and tritium, two isotopes of hydrogen, while particle beams, radio waves and microwaves heat it to 270 million degrees Fahrenheit, the temperature needed to sustain the fusion reaction. During the reaction, the deuterium and tritium nuclei fuse, producing helium and a neutron. In a fusion power plant, those energetic neutrons would heat a structure, called a blanket, in the tokamak and that heat would be used to turn a turbine to produce electricity.
The ITER reactor will be the largest tokamak ever made, producing 500 megawatts of power, about the same output as a coal-fired power plant. But ITER won’t generate electricity; it’s just a gigantic physics experiment, albeit one with very high potential benefits. A mere 35 thousandths of an ounce of deuterium-tritium fuel could produce energy equivalent to 2,000 gallons of heating oil. And ITER’s process is “inherently safe,” says Richard Pitts, a senior scientific officer on the project. “It can never, ever be anything like what you see in the fission world--in Chernobyl or Fukushima--and this is why it is so attractive.”
ITER's magnets produce fields at least 1,000 times as strong as the magnets stuck to your refrigerator.To fully commercialize tokamak-based fusion, developers must overcome several challenges. First is the matter of breeding the tritium; there are only about 50 pounds of it in the world at any given time because it is not naturally occurring and decays quickly. (Deuterium is not radioactive and can be distilled from water.) Although ITER may use tritium produced by nuclear power plants, a full-scale fusion plant will need to produce its own supply--neutrons from the fusion reaction could be used to convert a stash of lithium into tritium. In addition, physicists must also determine which materials can best withstand the by-products of the fusion reaction, which will wear down the tokamak’s walls. Finally, residual radioactivity in the device will pose maintenance problems because people won’t be able to work safely within the vessel. ITER scientists must develop robots capable of replacing parts that can weigh up to 10 tons.
ITER will begin experiments in 2019 in France. If those are successful, the data produced by the project will aid the ITER team in the design of DEMO, a proposed 2,000- to 4,000-megawatt demonstration fusion power plant that will be built by 2040.
(Click the above image for more information.)
German Lab Generates the Strongest Magnetic Field Ever Created
That’s a lot of teslas. Your standard high-power copper coil would be torn apart at something like 25 teslas, the researchers say. That’s because the magnetic field and the electric current that creates it work at cross purposes at higher energies. The current running through the coil generates the magnetic field, but the magnetic field pushes back against the electrons flowing through the coil. The stronger the current, the more the magnetic field pushes back, and once the current crosses a certain threshold the magnet will quite literally tear itself apart.
But we need bigger, badder magnets. The higher and more precise magnetic fields we can produce in the lab, the better we can test and characterize the properties of the materials we create, things like superconductors that shuttle electrons around with zero resistance. In order to make their magnet withstand the pressures of 90-plus teslas, the HZDR team wrapped the coil in a specially fabricated corset made of high-tensile fibers usually used in body armor.
That gave them a small coil with enough strength to stand up to 50 teslas for a brief two-hundredths of a second. So they did what seems natural and added another magnet, wrapping a second, 12-layer copper coil also swathed in a fiber corset around the first. This larger magnet can only withstand a 40 tesla field, but combined with the other 50 teslas the combo magnet can achieve more than 90 teslas.
The magnet has already drawn interest from materials scientists around the globe, and the HZDR aims to produce another six magnets over the next few years to accommodate all the researchers who want time on the devices. The record replaces one set by American researchers at Los Alamos National Labs that had stood for years.
New Alloy Can Convert Heat Directly Into Electricity
Multiferroic materials possess both magnetism and ferroelectricity, or a permanent electric polarization. Materials with both of these properties are very rare; check out from the National Institute of Standards and Technology if you’re interested in the electron orbital arrangements that cause these phenomena.
In this case, the new alloy — Ni45Co5Mn40Sn10 — undergoes a reversible phase transformation, in which one type of solid turns into another type of solid when the temperature changes, according to a news release from the University of Minnesota. Specifically, the alloy goes from being non-magnetic to highly magnetized. The temperature only needs to be raised a small amount for this to happen.
When the warmed alloy is placed near a permanent magnet, like a rare-earth magnet, the alloy’s magnetic force increases suddenly and dramatically. This produces a current in a surrounding coil, according to the researchers, led by aerospace engineering professor Richard James. Watch a piece of the alloy leap over to a permanent magnet in the video clip below.
A process called hysteresis causes some of the heat energy to be lost, but this new alloy has a low hysteresis, the researchers say. Because of this, it could be used to convert waste heat energy into large amounts of electricity.
One obvious use for this material would be in the exhaust pipes of vehicles. Several automakers are already working on heat transfer devices that can into usable electricity; General Motors is using alloys called skutterudites, which are cobalt-arsenide materials doped with rare earths.
Rare earth magnets are already a necessity in many , so heat-capture devices made of the new multiferroic compound could be placed near the magnets.
The material could also be used in power plants or even ocean thermal energy generators, the researchers said.
A paper on the alloy was published in the journal Advanced Energy Materials.
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Using Magnets and Stink Bombs to Keep Sharks at Bay
The discovery earned Shark Defense $25,000 from the World Wildlife Fund’s annual International Smart Gear Competition, which rewards inventors who develop new methods to keep animals from getting tangled in commercial fishing lines. Shark Defense is now investigating ways to embed the metals in nets. And Stroud says the same metals, worn as an anklet, could act as a personal shark deterrent.
The company is also working on a chemical repellent, a slightly sweet-smelling combination of a dozen compounds that mimics the scent of rotting shark. Patrick Rice, the senior marine biologist at Shark Defense, has developed the repellent in several forms: as a pressurized can of aerosol spray that can create a 50-milliliter cloud and is popular with spear fishers, a pouch that bursts underwater to quickly clear an area, and a gel that can be injected into bait to keep sharks from getting hooked. The chemical repellent is less expensive than rare-earth magnets. Still, Rice says, “just like anything else, nothing’s 100 percent effective. If sharks are in a frenzied state, if they’re hungry enough, they’ll start eating.”
Adapted from Juliet Eilperin's book, .
Bumped from Endeavour Flight, Madly Powerful British Supermagnet Looks for Work Elsewhere
It could bend harmful radiation away from astronauts, or focus plasma for a novel propulsion engine
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In order for AMS to study those incoming high-energy particles, it needs to know their charges. To determine this, the experiment will rely on a very strong magnet to bend the particles--how they bend says a lot about their charge, which says a lot about where the particles came from. These kinds of magnets have to be specially designed (they are cooled with liquid helium to very low temperatures, and thus are not your average magnet), and the UK’s own Scientific Magnetics spent more than a decade developing one for the AMS.
Then, a year ago, the magnet was booted from Endeavour’s flight. When it was determined last year that the ISS’s life would be extended to 2020 researchers decided they wanted a longer-lived magnet. They opted for a less powerful option with a longer lifespan, and Scientific Magnetics’ magnet was put on the shelf.
But such a precise, high-powered magnet (shaped like a hollow cylinder, it points its entire field inward) is too rare and awesome to go to waste. There are a few potential uses for it, the , notes, neither of which will likely see the magnet launched into space but both enabling critical future space travel technologies.
First, it could be used to study the ways a huge, hollow cylindrical magnet--one several meters in diameter--could be used to shield future astronauts from cosmic rays in space. Such a magnet would actually wrap around a habitat and project its magnetic field outward, leaving the interior magnetic field-free. But on the outside, it could deflect cosmic rays, making a future moon base or long-term deep space flight more hospitable to humans.
This technology could also help power a future deep space mission via ion propulsion. Ion propulsion engines require the crafting of finely tuned magnetic fields that can mold the shape of highly excited gases and plasmas as they are released to create thrust without combustion. In such engines, the magnets function as nozzles that optimize and control the plasma flow to provide the kind of thrust that could (theoretically) get a spacecraft to Mars in weeks rather than months.
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Video: Powerful Magnets Pointed At British Editor’s Head Prevent Him From Reciting A Nursery Rhyme
Magnetic fields applied to the brain can be used to , and even and sense of morality. But unless you’re a neuroscientist, it’s hard to see the physiology of this phenomenon, other than trying to interpret colorful brain scans.
The following video accomplishes this beautifully. And not just because it cuts off a science editor’s ability to speak.
Watch below as New Scientist editor of "Humpty Dumpty" is interrupted by magnetic interference. Vincent Walsh from the Institute of Cognitive Neuroscience at University College London used magnets to shut off Highfield’s speech center, the British science mag reports.
Transcranial magnetic stimulation, as this is called, is a useful way to inhibit specific regions of the brain. Along with boosting visual memory, it can make you , for instance. It’s even been shown to ; DARPA is studying the technique for , allowing soldiers to manipulate brain functions to boost alertness, relieve stress or reduce the effects of traumatic brain injury.
Walsh and colleagues are studying the use of the technique to treat migraine and stroke, New Scientist says.
At publication time, PopSci editors were as yet unwilling to duplicate the experiment.
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