Levitated dipole

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Plasma in the Levitating Dipole Experiment

A levitated dipole is a type of

fusion reactor was first theorized by Akira Hasegawa in 1987.[2]

Concept

The Earth's magnetic field is generated by the circulation of charges in the Earth's molten core. The resulting magnetic dipole field forms a shape with magnetic field lines passing through the Earth's center, reaching the surface near the poles and extending far into space above the equator. Charged particles entering the field will tend to follow the lines of force, moving north or south. As they reach the polar regions, the magnetic lines begin to cluster together, and this increasing field can cause particles below a certain energy threshold to reflect, and begin travelling in the opposite direction. Such particles bounce back and forth between the poles until they collide with other particles. Particles with greater energy continue towards the Earth, impacting the atmosphere and causing the aurora.

This basic concept is used in the

fusion breakeven
in a practically sized device.

The levitated dipole can be thought of, in some ways, as a toroidal mirror, much more similar to the Earth's field than the linear system in a traditional mirror. In this case, the confinement area is not the linear area between the mirrors, but the toroidal area around the outside of the central magnet, similar to the area around the Earth's equator. Particles in this area that move up or down see increasing magnetic density and tend to move back towards the equator area again. This gives the system some level of natural stability. Particles with higher energy, the ones that would escape a traditional mirror, instead follow the field lines through the hollow center of the magnet, recirculating back into the equatorial area again.

This makes the levitated dipole unique when compared with other

Hasegawa-Mima equation) after participating in the Voyager 2 encounter with Uranus.[2]

Examples

See also: Levitated Dipole Experiment
The Levitated Dipole Experiment (LDX)

The concept of the levitated dipole was first realized when Jay Kesner of MIT and Michael Mauel of Columbia University made a joint proposal to test the concept in 1997.[3] This led to the development of two experiments: the Levitated Dipole Experiment (LDX) at MIT and the Collisionless Terrella Experiment (CTX) at Columbia University.[4]

References

  1. ^ "MIT tests unique approach to fusion power". MIT News, David Chandler, MIT News Office, March 19, 2008. Accessed March 2008
  2. ^
    ISSN 0374-2806
    .
  3. Bibcode:1997PlPhR..23..742K
    .
  4. ^ "CTX". sites.apam.columbia.edu. Retrieved 2020-06-22.
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