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Columbia 's Stellarator Project Gets Jolt from National Science Foundation

This picture, taken through a window on the stellarator's vacuum chamber, shows the bright blue glow of nitrogen plasma created by electrons traveling on a magnetic surface shaped like a twisted donut.

The Sun, with its seemingly endless supply of energy, is powered by nuclear fusion. Why can't a similar process provide an unlimited energy supply on Earth?

The answer to this and other questions fundamental to our understanding of the early universe may emerge from research by scientists using Columbia's stellarator. The machine, essentially a giant "magnetic bottle" shaped like a twisted doughnut, confines electrons for an extended period of time, enabling scientists to conduct tightly controlled experiments.

The stellarator is devoted exclusively to this kind of research, says Thomas Sunn Pedersen, assistant professor of applied physics, who designed and oversaw its construction in 2004. The device is so large that it had to be backed into The Fu Foundation School of Engineering and Applied Science on an 18-wheel tractor trailer.

By confining electrons in tightly controlled experiments for longer periods of time, the stellarator may be able to create electron-positron plasmas for the first time on Earth, allowing researchers to study them up close.

Plasma is the fourth state of matter (along with solids, liquids and gases), and accounts for some 99 percent of our visible universe, from stars to man-made items such as fluorescent light bulbs.

Columbia 's stellarator, seen here in the Columbia Plasma Physics Laboratory, is designed to conduct the first investigation of non-neutral plasmas confined on magnetic surfaces.

Scientists have studied regular plasmas intensely in laboratories, but never electron-positron plasmas. Because the differences and similarities between regular plasmas and electron-positron plasmas have yet to be confirmed experimentally, it's fertile territory for Pedersen and plasma physicists around the world.

Pedersen's research on electron-positron or "matter-antimatter" plasmas is significant because these plasmas are believed to exist around neutron stars and massive black holes, such as the super massive black hole at the center of our galaxy.

New information about this special type of plasma and the ability to confine it for longer periods could lead to a greater understanding of our universe and could help speed up the development of a commercially viable way to tap fusion as an energy supply.

Fusion energy results when nuclei overcome the repulsive forces of their positive charges during high-speed collisions and begin to fuse.

Although the sun and stars are fusion reactors, the production of useful controlled fusion on earth has not yet been achieved, despite decades of effort. One of the problems lies in confining the plasma long enough for appreciable fusion to occur.

For his efforts, Pedersen has been recognized by the National Science Foundation's Faculty Early Career Development (CAREER) Program for ground-breaking work in plasma physics.

CAREER offers the National Science Foundation's most prestigious award to the early career-development activities of teacher-scholars who most effectively integrate research and education within the context of the mission of their organization. The award translates to $800,000 over five years and is expected to begin in September.

According to Pedersen, recent results show that over 100 billion electrons can be confined in the Columbia Non-neutral Torus experiment currently underway at the stellarator. Ordinarily, such a cloud of electrons suspended in a vacuum would fly apart in a fraction of a microsecond, due to the mutual repulsion of all the electrons, like charged magnets scooting apart when placed near each other.

Pedersen says this is only the beginning.

"As we get to understand these plasmas better, we expect to increase the confinement time in the stellarator by at least another factor of a hundred," he said.

For more information on the Columbia stellarator, visit http://www.ap.columbia.edu/CNT/CNT-main.htm. For information on the CAREER program, click here: http://www.nsf.gov/funding/pgm_summ.jsp?pims_id=5262

Published: Jul 29, 2005
Last modified: Jul 29, 2005

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