page_title: Fusor
section_title: Mechanism
hierarchical_section_title: Fusor / Mechanism
caption_attribution_description: English: This is an illustration of the fusion mechanisms in a fusor; also known as a Hirsch-farnsworth fusor or a Spherically Convergent Ion Focus (SCIF). This description is taken from the dissertation: "Ion Flow and fusion reactivity characterization of a spherically convergent ion focus" by Tim Thorson, Wisconsin-Madison, 1996. (1) The fusor contains two wire cages - also known as grids - one inside the other. The inner cage is the cathode, while the outer cage is the anode. Ions are introduced, injected or generated inside the two cages. (2) The ions accelerate down the voltage drop towards the inner cage. The electric field is doing physical work on the ions, heating them, to fusion conditions. (3) The ions must miss the inner cage. (4) If they collide, or are concentrated in the center grid, they can fuse. This is the basic mechanism for nuclear fusion in fusors. Other information This is an illustration of the fusion mechanisms in a fusor; also known as a Hirsch-farnsworth fusor or a Spherically Convergent Ion Focus (SCIF). This description is taken from the dissertation: "Ion Flow and fusion reactivity characterization of a spherically convergent ion focus" by Tim Thorson, Wisconsin-Madison, 1996. (1) The fusor contains two wire cages - also known as grids - one inside the other. The inner cage is the cathode, while the outer cage is the anode. Ions are introduced, injected or generated inside the two cages. (2) The ions accelerate down the voltage drop towards the inner cage. The electric field is doing physical work on the ions, heating them, to fusion conditions. (3) The ions must miss the inner cage. (4) If they collide, or are concentrated in the center grid, they can fuse. This is the basic mechanism for nuclear fusion in fusors.
context_page_description: A fusor is a device that uses an electric field to heat ions to nuclear fusion conditions. The machine induces a voltage 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 one kind of an inertial electrostatic confinement device – a branch of fusion research.
  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 type 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.
context_section_description: For every volt that an ion of ±1 charge is accelerated across it gains 1 electronvolt in energy, similar to heating a material by 11,604 kelvins in temperature (T = eV / kB). After being accelerated by 15 kV a singly-charged ion has a kinetic energy of 15 keV, similar to the average kinetic energy at a temperature of approximately 174 megakelvins, a typical magnetic confinement fusion plasma temperature. Because most of the ions fall into the wires of the cage, fusors suffer from high conduction losses. On a bench top, these losses can be at least five orders of magnitude higher than the energy released from the fusion reaction, even when the fusor is in star mode.  Hence, no fusor has ever come close to break-even energy output. The common sources of the high voltage are ZVS flyback HV sources and neon-sign transformers. It can also be called a particle accelerator.
caption: An illustration of the basic mechanism of fusion in fusors.  (1) The fusor contains two concentric wire cages: the cathode is inside the anode.  (2) Positive ions are attracted to the inner cathode, they fall down the voltage drop.  The electric field does work on the ions, heating them to fusion conditions. (3) The ions miss the inner cage. (4) The ions collide in the center and may fuse.[20]
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