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n. (context astronomy English) A celestial body that, through self-gravity, is able to perform nuclear fusion within its core, at any point in its life. These include stars, stellar remnants, and brown dwarfs.


A fusor is a device that uses an electric field to heat ions to conditions suitable for nuclear fusion. The machine generates an electric potential difference between two metal cages inside a vacuum. Positive ions fall down this voltage drop, building up speed. If they collide in the center, they can fuse. This is a type of inertial electrostatic confinement device.

A Farnsworth–Hirsch fusor is the most common type of fusor. This design came from work by Philo T. Farnsworth in 1964 and Robert L. Hirsch in 1967. A variant of fusor had been proposed previously by William Elmore, James L. Tuck, and Ken Watson at the Los Alamos National Laboratory though they never built the machine.

Fusors have been built by various institutions. These include academic institutions such as the University of Wisconsin–Madison, the Massachusetts Institute of Technology and government entities, such as the Atomic Energy Organization of Iran and the Turkish Atomic Energy Authority. Fusors have also been developed commercially, as sources for neutrons by DaimlerChrysler Aerospace and as a method for generating medical isotopes. Fusors have also become very popular for hobbyists and amateurs. A growing number of amateurs have performed nuclear fusion using simple fusor machines.

Fusor (astronomy)

A fusor, according to a proposal to the IAU by Gibor Basri, Professor of Astronomy at the University of California, Berkeley to help clarify the nomenclature of celestial bodies, is "an object that achieves core fusion during its lifetime". This definition included any form of nuclear fusion, so the lowest possible mass of a fusor was set at roughly 13 times that of Jupiter, at which point deuterium fusion becomes possible. This is significantly smaller than the point at which sustained hydrogen fusion becomes possible, around 60 times the mass of Jupiter. Objects are considered "stellar" when they are about 75 times the mass of Jupiter, when gravitational contraction, i.e. contraction of the object due to gravity, is halted by heat generated by the nuclear reaction in their interiors. Fusors would include active stars, dead stars, and brown dwarfs.

The introduction of the term "fusor" would allow for a simple definition:

  • Fusor – An object capable of core fusion
  • Planemo – A round nonfusor
  • Planet – A planemo that orbits a fusor

where round is understood as "whose surface is very nearly on the gravitational equipotential", orbits means "whose primary orbit is now, or was in the past around", and capable implies fusion is possible sometime during the existence of the object by itself.

Fusor (disambiguation)

Fusor or Fuzor may refer to:

  • Fusor or the Farnsworth–Hirsch Fusor, an apparatus designed by Philo T. Farnsworth to create nuclear fusion
  • Fusor (astronomy), an object that achieves core fusion during its lifetime
  • Fuzors, a Transformers sub-line (toys, comics and cartoons)
  • Zoids Fuzors, an anime

Usage examples of "fusor".

The basic lumpy mountain was then cut and shaped with fusors and carefully triggered landslides, filled, planted, landscaped, and finally frosted with snow and even a small glacier near the summit.