Editing Fusor (section)

=== In fusors ===
In the original fusor design, several small [[particle accelerator]]s, essentially TV tubes with the ends removed, inject ions at a relatively low voltage into a [[vacuum]] chamber. In the Hirsch version of the fusor, the ions are produced by ionizing a dilute gas in the chamber. In either version there are two concentric spherical [[electrode]]s, the inner one being charged negatively with respect to the outer one (to about 80 kV). Once the ions enter the region between the electrodes, they are accelerated towards the center.

In the fusor, the ions are accelerated to several keV by the electrodes, so heating as such is not necessary (as long as the ions fuse before losing their energy by any process). Whereas 45 megakelvins is a very high temperature by any standard, the corresponding voltage is only 4 kV, a level commonly found in such devices as [[neon sign]]s and CRT televisions. To the extent that the ions remain at their initial energy, the energy can be tuned to take advantage of the peak of the reaction [[cross section (physics)|cross section]] or to avoid disadvantageous (for example neutron-producing) reactions that might occur at higher energies.

Various attempts have been made at increasing deuterium ionization rate, including heaters within "ion-guns", (similar to the "electron gun" which forms the basis for old-style television display tubes), as well as [[magnetron]] type devices, (which are the power sources for microwave ovens), which can enhance ion formation using high-voltage electromagnetic fields.  Any method which increases ion density (within limits which preserve ion mean-free path), or ion energy, can be expected to enhance the fusion yield, typically measured in the number of neutrons produced per second.
 
The ease with which the ion energy can be increased appears to be particularly useful when [[aneutronic fusion|"high temperature" fusion reactions]] are considered, such as [[proton-boron fusion]], which has plentiful fuel, requires no radioactive [[tritium]], and produces no neutrons in the primary reaction.