LDX: MIT tests unique approach to fusion power

An MIT and Columbia University team has successfully tested a novel reactor that could chart a new path toward nuclear fusion, which could become a safe, reliable and nearly limitless source of energy.

Begun in 1998, the Levitated Dipole Experiment, or LDX, uses a unique configuration where its main magnet is suspended, or levitated, by another magnet above. The system began testing in 2004 in a “supported mode” of operation, where the magnet was held in place by a support structure, which causes significant losses to the plasma–a hot, electrically charged gas where the fusion takes place.

LDX achieved fully levitated operation for the first time last November. A second test run was performed on March 21-22 of this year.

The advantage of the levitating system is that it requires no internal supporting structure, which would interfere with the magnetic field lines surrounding the donut-shaped magnet, explains Jay Kesner of MIT’s Plasma Science and Fusion Center, joint director of LDX with Michael Mauel of Columbia. That allows the plasma inside the reactor to flow along those magnetic field lines without bumping into any obstacles that would disrupt it (and the fusion process).

To produce a sustained fusion reaction the right kinds of materials must be confined under enormous, pressure, temperature and density. The “fuel” is typically a mix of deuterium and tritium (known as a D-T cycle), which are two isotopes of hydrogen, the simplest atom. A normal hydrogen atom contains just one proton and one electron, but deuterium adds one neutron, and tritium has two neutrons. So far, numerous experimental reactors using different methods have managed to produce some fusion reactions, but none has yet achieved the elusive goal of “breakeven,” in which a reactor produces as much energy as it consumes. To be a practical power source, of course, will require it to put out more than it consumes.

source: http://www.physorg.com/news125929881.html