Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

150-ton magnet pulls world toward new energy source

24.09.2002


MIT team is part of project

A 150-ton magnet developed in part by MIT engineers is pulling the world closer to nuclear fusion as a potential source of energy.

Over the last three years "we’ve shown that we can design a magnet of this size and complexity and make it work," said Joseph V. Minervini, a senior research engineer at MIT’s Plasma Science and Fusion Center (PSFC) and Department of Nuclear Engineering. Minervini leads the MIT team involved in the project.



He notes, however, that a better understanding of certain results is necessary to reduce costs for the researchers’ ultimate goal: a magnet weighing 925 tons that will be key to the International Thermonuclear Experimental Reactor (ITER). That magnet, in turn, will be part of a total magnet system weighing some 10,000 tons.

ITER goals include demonstrating the feasibility of nuclear fusion as an energy source, which Congress has recently shown increased interest in. Last week a Department of Energy panel recommended that the United States re-join the multi-nation ITER collaboration. In 1999 Congress appropriated funding for completion of R&D commitments toward ITER, but not for an extension of US participation in the project.

In nuclear fusion, light elements are fused together at enormous pressures to make heavier elements, a process that releases large amounts of energy. Powerful magnets provide the magnetic fields needed to initiate, sustain, and control the plasma, or electrically charged gas, in which fusion occurs.

The 150-ton magnet in Japan is a testbed for the 925-ton magnet that will ultimately initiate and heat the ITER plasma. Two additional mammoth magnet systems will confine the plasma and control its shape. A model for one of these is currently being tested in Germany; a model of the second is planned.

WEIGHTY TESTBED

The cylindrical 150-ton magnet has three principal parts: an outer module built by a Japanese team, an inner module built by a US team, and a thin "insert" coil near the core that is fitted with instrumentation to "tell what’s going on," Minervini said. Three different inserts have been separately tested; two of these were built by Japan, the other by Russia.

Three sets of tests on the magnet since 2000 have taught the engineers more about magnet performance on such a grand scale. The first test in 2000 showed that the inner and outer modules did indeed work (see MIT Tech Talk May 3, 2000).

Later in the same run the researchers tested one of the Japanese inserts. The overall device produced a magnetic field of 13 tesla (about 260 thousand times more powerful than the Earth’s magnetic field) with a stored energy of 640 megajoules at a current of 46,000 amperes (about 3,000 times the current handled by typical household wiring).

Most importantly, however, the team found that they could successfully operate the magnet in pulses, bringing it to 13 tesla and back down in a few seconds. "The magnet is only doing its job for this particular magnetic fusion application when we’re changing the magnetic field," or ramping it up and down, Minervini explained.

A superconducting magnet operated on a constant current, such as those used in Magnetic Resonance Imaging of the body, suffers no dissipation of electrical energy. That is not true, however, when a superconducting magnet is pulsed. And tests of the new magnet in pulsed operation showed that "initially [the electrical] losses were much higher than predicted," Minervini said.

With repeated operation, however, the magnet appeared to correct itself. "With each cycle the losses lessened until they reached a steady value a lot closer to what we’d predicted," Minervini said.

"We think we understand what’s happening, at least qualitatively," he continued. "It has to do with interactions between the thousands of wires twisted into cables that in turn are coiled to form the magnet. We are essentially changing the electrical characteristics of the cable in a way that decreases losses over time."

CONTROLLING COSTS

The team also explored the magnet’s limits for three key parameters related to maintaining superconductivity: magnetic field, temperature, and current density. "We don’t want to run at the limits of these," Minervini said. "Rather, we want to run within margins that give us some leeway."

The tests, however, showed that these margins are harder to define than expected. "This is a cost issue," Minervini said. "If you know exactly where the margins are, you don’t have to build in as much leeway, which is expensive."

In addition to the first tests in 2000, the team also ran tests in 2001 of a Russian insert and, earlier this year, of a second Japanese insert made of a different kind of superconducting wire.

"We still have a lot of data to analyze for all three test runs," Minervini concluded, "but we’ve shown that the whole thing actually works."

Some 20 MIT PSFC researchers have been involved in the work. Fabrication of the US portion of the magnet was funded by the Department of Energy, primarily through a multi-year grant to MIT. Other US industrial tasks were performed by more than 20 vendors.

Elizabeth Thomson | EuekAlert!

More articles from Power and Electrical Engineering:

nachricht Researchers pave the way for ionotronic nanodevices
23.02.2017 | Aalto University

nachricht Microhotplates for a smart gas sensor
22.02.2017 | Toyohashi University of Technology

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>