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 Robot on demand: Mobile machining of aircraft components with high precision
06.12.2016 | Fraunhofer IFAM

nachricht IHP presents the fastest silicon-based transistor in the world
05.12.2016 | IHP - Leibniz-Institut für innovative Mikroelektronik

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: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Porous crystalline materials: TU Graz researcher shows method for controlled growth

07.12.2016 | Materials Sciences

Simple processing technique could cut cost of organic PV and wearable electronics

06.12.2016 | Materials Sciences

3-D printed kidney phantoms aid nuclear medicine dosing calibration

06.12.2016 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>