Building a Fusor (a Polywell's Grandmother)

The concept is straightforward enough that undergraduate college students with some knowledge of physics, the required technology, and about $3000 can make a fusor.  Indeed, several already have.  For example, a group of physics students at Peninsula College in Port Angeles, USA built a fusor in the spring of 2008. Left to right above: Devon McMinn, Ivan Hui, Sarah Mangiameli, Chris Milroy, Aaron Stoll, and Derek Madison.  Advisor Jeff Zirul is not pictured.

Above is the Peninsula vacuum chamber.  The approximate diameter of the chamber was 0.15 m (6 inches). The camera view port is at top center.  The deuterium gas feed pipe is top left.  Neutron production is the best proof that fusion has occurred. It may be that a Bubble Detector is now the most cost-effective way to detect neutrons. The glass bubble detector vial is about 0.16 m to the right of the chamber center above. Below is a close-up shot of the bubble from one neutron. The Peninsula group bought their bubble detector from Yale University for $80, but Yale sells only to other institutions.

Below are the Peninsula grids before they were installed in the vacuum chamber. 

When in use, the larger outer wire grid (above left) is at plus 10,000 volts and makes ions by ripping electrons from the deuterium molecules on contact.  The inner smaller grid (above roght), at negative 15,000 volts, accelerates the ions across a total field difference of 25,000 volts.

Above is the inside of the Peninsula college fusor in operation.  The pressure was about 1 x 10-3 Torr.  Such a pressure can be attained with  a “roughing” pump used for refrigerator repair.  The glow in the photo is not nuclear fusion, it is only a “Paschen” or discharge glow, similar to that produced by a neon sign.  Indeed, the high voltage necessary can be obtained from the transformer of just such a neon sign.