Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Physicists set 'speed limit' for future superconducting magnet

12.02.2007
A research team led by a Northwestern University physicist has identified a high-temperature superconductor -- Bi-2212, a compound containing bismuth -- as a material that might be suitable for the new wires needed to one day build the most powerful superconducting magnet in the world, a 30 Tesla magnet.

The material currently used in magnetic resonance (MR) imaging machines in both hospitals and research laboratories -- a low-temperature superconducting alloy of the metallic element niobium -- has been pushed almost as far as it can go, to around 21 Tesla. (Tesla is used to define the intensity of the magnetic field.) There are no superconducting magnet wires currently available that can generate 30 Tesla.

"A new materials technology -- such as a technology based on high-temperature superconductivity -- is required to make the huge leap from 21 Tesla to 30 Tesla," said William P. Halperin, John Evans Professor of Physics and Astronomy in the Weinberg College of Arts and Sciences at Northwestern, who led the team. "We have shown that Bi-2212 could be operated at the same temperature as is presently the case for magnets made with niobium -- 4 degrees Kelvin -- and also achieve the stable state necessary for a 30 Tesla magnet."

The findings will be published online Feb. 11 by the journal Nature Physics.

"We are exploring nature's limitations, and our discovery has basic implications for the study of superconductors and for applications to magnetic resonance imaging," said Halperin. "The dream would be to have powerful magnets that don't require helium for cooling. Some day new materials might be discovered where this restriction is lifted, but it isn't possible at the present time."

A superconductor, when cooled to its appropriate temperature, conducts electricity without any resistance. Superconductivity first appears in Bi-2212 at a high temperature of 90 degrees Kelvin, but Halperin and his colleagues found that the stable state required in high-magnetic fields can be established only when the temperature falls below 12 degrees Kelvin. The team is the first to establish this limit for Bi-2212.

"Sometimes what seems to be bad can be good," said Bo Chen, lead author of the paper and a graduate student of Halperin's. "Our findings set a speed limit. If you go beyond this speed you may have trouble. Knowing the upper temperature limit is a kind of security."

"To create a 30 Tesla magnet, we need a superconducting material that can carry the required amount of electricity without blowing up," said Halperin. "We have found that the operating temperature for Bi-2212 must be below 12 degrees Kelvin. The good news is that this temperature can be reached by cooling the magnet with liquid helium. If we had found the upper limit to be 2 degrees Kelvin then the cryogenic requirements would be intractable."

MR imaging is widely used by hospitals for medical diagnosis, and scientists at universities, national laboratories and pharmaceutical companies use even more powerful MR technology to study DNA, proteins and other complex molecules. About a dozen labs around the country take advantage of the highest magnetic field now in use -- 21.1 Tesla, which produces a magnetic field 10 times larger than your average hospital machine. Increasing the field of the magnet even a small amount, from 21.1 to 22.2 Tesla, would increase the cost of the machine by two million dollars.

"A holy grail of the scientific community, as set out recently by the National Research Council, is to build a superconducting magnet of 30 Tesla," said Halperin. "In MR imaging, the higher the magnetic field, the higher the resolution, which provides scientists with more detail for analysis. A 30 Tesla magnet could drive significant advances in chemistry, biology and medicine."

Using MR techniques at the National High Magnetic Field Laboratory in Tallahassee, Fla., Halperin and his team studied Bi-2212, one of the "darlings" of superconductivity. To measure its properties, they put the rare isotope oxygen-17 into a crystal of Bi-2212, with the isotope acting as a probe, much like a fluorescent dye. They then determined the phase diagram of the material where superconductivity is stable, which showed high temperature and high magnetic field could not be achieved together.

"Now that we have this information about Bi-2212, the next question is, 'Can such a magnet actually be made?'" said Halperin. "I really don't know -- it depends on engineering and processing the materials to make them into wires. My fellow scientists and engineers will have to solve the materials problems, and they don't like to accept no as an answer."

Megan Fellman | EurekAlert!
Further information:
http://www.northwestern.edu

More articles from Physics and Astronomy:

nachricht First Juno science results supported by University of Leicester's Jupiter 'forecast'
26.05.2017 | University of Leicester

nachricht Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>