Featured Research

from universities, journals, and other organizations

Physicists Set 'Speed Limit' For Future Superconducting Magnet

Date:
February 12, 2007
Source:
Northwestern University
Summary:
The material currently used in magnetic resonance imaging machines -- a low-temperature superconducting alloy of niobium -- has been pushed almost as far as it can go, to around 21 Tesla. Now a team led Northwestern University researchers has identified a high-temperature superconductor -- called Bi-2212 -- 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.

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.

Related Articles


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."

In addition to Halperin and Chen, the research team includes Vesna F. Mitrovic, of Brown University, and Arneil P. Reyes and Philip L. Kuhns, of the National High Magnetic Field Laboratory, as well as crystal growers Prasenjit Guptasarma, of the University of Wisconsin-Milwaukee, and David G. Hinks, of Argonne National Laboratory.


Story Source:

The above story is based on materials provided by Northwestern University. Note: Materials may be edited for content and length.


Cite This Page:

Northwestern University. "Physicists Set 'Speed Limit' For Future Superconducting Magnet." ScienceDaily. ScienceDaily, 12 February 2007. <www.sciencedaily.com/releases/2007/02/070211200700.htm>.
Northwestern University. (2007, February 12). Physicists Set 'Speed Limit' For Future Superconducting Magnet. ScienceDaily. Retrieved March 5, 2015 from www.sciencedaily.com/releases/2007/02/070211200700.htm
Northwestern University. "Physicists Set 'Speed Limit' For Future Superconducting Magnet." ScienceDaily. www.sciencedaily.com/releases/2007/02/070211200700.htm (accessed March 5, 2015).

Share This


More From ScienceDaily



More Matter & Energy News

Thursday, March 5, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Did the Simpsons Figure out the Higgs Boson Particle Years Before Scientists

Did the Simpsons Figure out the Higgs Boson Particle Years Before Scientists

Buzz60 (Mar. 4, 2015) During a 1998 Simpsons episode, Homer Simpson scribbled a seemingly gibberish equation on a chalkboard. Turns out that equation is a shake off from predicting the actual nano mass of the God Particle. Patrick Jones (@Patrick_E_Jones) explains. Video provided by Buzz60
Powered by NewsLook.com
Wearables Now the Must-Haveables

Wearables Now the Must-Haveables

Reuters - Business Video Online (Mar. 3, 2015) Telecom company executives are meeting in Barcelona for the Mobile World Congress, the largest annual trade show for the wireless industry. As Ivor Bennett reports from the show wearable technology is one of the big themes. Video provided by Reuters
Powered by NewsLook.com
Forensic Holodeck Creates 3D Crime Scenes

Forensic Holodeck Creates 3D Crime Scenes

Reuters - Innovations Video Online (Mar. 3, 2015) A holodeck is no longer the preserve of TV sci-fi classic Star Trek, thanks to researchers from the Institute of Forensic Medicine Zurich, who have created what they say is the first system in the world to visualise the 3D data of forensic scans. Jim Drury saw it in operation. Video provided by Reuters
Powered by NewsLook.com
Solar Plane Passes New Test Ahead of World Tour

Solar Plane Passes New Test Ahead of World Tour

AFP (Mar. 2, 2015) A solar-powered plane made a third successful test flight in the United Arab Emirates on Monday ahead of a planned round-the-world tour to promote alternative energy. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins